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  • 251. Cael, B. B.
    et al.
    Seekell, David A.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    The size-distribution of Earth's lakes2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 29633Article in journal (Refereed)
    Abstract [en]

    Globally, there are millions of small lakes, but a small number of large lakes. Most key ecosystem patterns and processes scale with lake size, thus this asymmetry between area and abundance is a fundamental constraint on broad-scale patterns in lake ecology. Nonetheless, descriptions of lake size-distributions are scarce and empirical distributions are rarely evaluated relative to theoretical predictions. Here we develop expectations for Earth's lake area-distribution based on percolation theory and evaluate these expectations with data from a global lake census. Lake surface areas >= 8.5 km(2) are power-law distributed with a tail exponent (T = 1.97) and fractal dimension (d = 1.38), similar to theoretical expectations (T = 2.05; d = 4/3). Lakes <8.5 km(2) are not power-law distributed. An independently developed regional lake census exhibits a similar transition and consistency with theoretical predictions. Small lakes deviate from the power-law distribution because smaller lakes are more susceptible to dynamical change and topographic behavior at sub-kilometer scales is not self-similar. Our results provide a robust characterization and theoretical explanation for the lake size-abundance relationship, and form a fundamental basis for understanding and predicting patterns in lake ecology at broad scales.

  • 252. Cai, Minggang
    et al.
    Hong, Qingquan
    Sun, Jionghui
    Sundqvist, Kristina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wiberg, Karin
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Department of Aquatic Sciences and Environmental Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Chen, Kai
    Wang, Yun
    Qiu, Cangrong
    Huang, Shuiying
    Concentrations, distribution and sources of polychlorinated dibenzo-p-dioxins and dibenzofurans and dioxin-like polychlorinated biphenyls in coastal sediments from Xiamen, China2016In: Marine Chemistry, ISSN 0304-4203, E-ISSN 1872-7581, Vol. 185, p. 74-81Article in journal (Refereed)
    Abstract [en]

    Xiamen and its surroundings are representative areas suffering from intense anthropogenic turbulence and contamination in southeast coast of China during rapid industrialization and urbanization period, thus relevant organic pollutants research is necessary to assess the coastal environmental quality and generate management strategy. Contamination status of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin like polychlorinated biphenyls (DL-PCBs) was investigated for 7 surface sediment samples collected in these areas in January 2007. The given data were used to evaluate the contamination and their potential risks of the pollutants. Concentrations of PCDD/Fs were in the range of 60 to 4089 pg g(-1) (dry weight) with an average of 1706 pg g(-1) and DL-PCBs in the range of 3 to 76 pg g(-1) with an average of 28 pg g(-1). Octa-chlorinated dibenzo-p-dioxin (OCDD) and PCBs 105 and 118 were the main congeners of the PCDD/F and DL-PCB, respectively. The toxicity equivalent concentrations (TEQs) were in the range of 0.15 to 5.2 pg g(-1) (average: 3.0 pg g(-1)) for PCDD/Fs, while in the range of <limit of quantitation (LOQ) to 0.09 pg g(-1) (average: 0.05 pg g(-1)) for DL-PCBs. Congener pattern analysis showed a dominance of OCDD, suggesting main sources were current or historical use of chlorophenol, current use of dioxin contaminated pesticides or atmospheric deposition. Due to the current levels of PCDD/Fs and DL-PCBs in this area, it is necessary to further research their biogeochemical processes and ecological influences in the future.

  • 253. Cairns, David M.
    et al.
    Lafon, Charles W.
    Mouton, Michelle F.
    Stuteville, Rachel L.
    Young, Amanda B.
    Moen, Jon
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Comparing two methods for ageing trees with suppressed, diffuse-porous rings (Betula pubescens ssp. czerepanovii)2012In: Dendrochronologia, ISSN 1125-7865, E-ISSN 1612-0051, Vol. 30, no 4, p. 252-256Article in journal (Refereed)
    Abstract [en]

    The annual growth rings of diffuse porous species such as mountain birch are often difficult to distinguish when samples are collected from trees that grow at treeline or in other harsh environments. In this study we document the differences in seedling and sapling ring counts obtained from two methods of analysis: a traditional analysis based on reflected light and low-power microscopy and one based on transmitted light with higher power magnification that uses thin-sections of the samples. Rings are easier to resolve using the more labor-intensive transmitted light method. Small rings are often missed when using the reflected light method, resulting in an underestimation of tree age. The dates estimated by the standard method agreed with those determined using the thin-sectioning method in 9.6% of the cases. Most commonly, the standard method gave a younger age than did thin-sectioning (72.4% of the trees). In only 18.03% of the cases did the standard method result in a greater age than did thin-sectioning. The reflected light method produced age estimations that were on average 1.37 years younger than those determined using the transmitted light method. The difference between the two methods was positively correlated with age and negatively correlated with mean ring-width. Age-class histograms based on the two methods show little difference at coarser aggregation levels (decades and pentads), but annualized age-class histograms have less agreement between the two methods. Therefore, we suggest using the more labor-intensive thin-sectioning method when annualized age counts are necessary in suppressed seedlings and saplings, for example, comparing tree establishment with annual climate conditions at treeline.

  • 254. Calbet, Albert
    et al.
    Sazhin, Andrey F.
    Nejstgaard, Jens C.
    Berger, Stella A.
    Tait, Zachary S.
    Olmos, Lorena
    Sousoni, Despoina
    Isari, Stamatina
    Martinez, Rodrigo A.
    Bouquet, Jean-Marie
    Thompson, Eric M.
    Båmstedt, Ulf
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Jakobsen, Hans H.
    Future Climate Scenarios for a Coastal Productive Planktonic Food Web Resulting in Microplankton Phenology Changes and Decreased Trophic Transfer Efficiency2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 4, p. e94388-Article in journal (Refereed)
    Abstract [en]

    We studied the effects of future climate change scenarios on plankton communities of a Norwegian fjord using a mesocosm approach. After the spring bloom, natural plankton were enclosed and treated in duplicates with inorganic nutrients elevated to pre-bloom conditions (N, P, Si; eutrophication), lowering of 0.4 pH units (acidification), and rising 3 degrees C temperature (warming). All nutrient-amended treatments resulted in phytoplankton blooms dominated by chain-forming diatoms, and reached 13-16 mu g chlorophyll (chl) a l(-1). In the control mesocosms, chl a remained below 1 mu g l(-1). Acidification and warming had contrasting effects on the phenology and bloom-dynamics of autotrophic and heterotrophic microplankton. Bacillariophyceae, prymnesiophyceae, cryptophyta, and Protoperidinium spp. peaked earlier at higher temperature and lower pH. Chlorophyta showed lower peak abundances with acidification, but higher peak abundances with increased temperature. The peak magnitude of autotrophic dinophyceae and ciliates was, on the other hand, lowered with combined warming and acidification. Over time, the plankton communities shifted from autotrophic phytoplankton blooms to a more heterotrophic system in all mesocosms, especially in the control unaltered mesocosms. The development of mass balance and proportion of heterotrophic/autotrophic biomass predict a shift towards a more autotrophic community and less-efficient food web transfer when temperature, nutrients and acidification are combined in a future climate-change scenario. We suggest that this result may be related to a lower food quality for microzooplankton under acidification and warming scenarios and to an increase of catabolic processes compared to anabolic ones at higher temperatures.

  • 255. Callaghan, Terry V.
    et al.
    Johansson, Margareta
    Brown, Ross D.
    Groisman, Pavel Ya.
    Labba, Niklas
    Radionov, Vladimir
    Barry, Roger G.
    Blangy, Sylvie
    Bradley, Raymond S.
    Bulygina, Olga N.
    Christensen, Torben R.
    Colman, Jonathan
    Essery, Richard L.H.
    Forbes, Bruce C.
    Forchhammer, Mads C.
    Frolov, Dimitry M.
    Golubev, Vladimir N.
    Grenfell, Thomas C.
    Honrath, Richard E.
    Juday, Glenn P.
    Melloh, Rae
    Meshcherskaya, Anna V.
    Petrushina, Marina N.
    Phoenix, Gareth K.
    Pomeroy, John
    Rautio, Arja
    Razuvaev, Vyacheslav N.
    Robinson, David A.
    Romanov, Peter
    Schmidt, Niels M.
    Serreze, Mark C.
    Shevchenko, Vladimir
    Shiklomanov, Alexander I.
    Shindell, Drew
    Shmakin, Andrey B.
    Sköld, Peter
    Umeå University, Faculty of Arts, Centre for Sami Research.
    Sokratov, Sergey A.
    Sturm, Matthew
    Warren, Stephen
    Woo, Ming-ko
    Wood, Eric F.
    Yang, Daquing
    Changing snow cover and its impacts2011In: Snow, Water, Ice and Permafrost in the Arctic (SWIPA): Climate Change and the Cryosphere, Oslo: Arctic Monitoring and Assessment Programme, 2011, p. 4:1-4:58Chapter in book (Refereed)
  • 256. Callaghan, Terry V.
    et al.
    Johansson, Margareta
    Brown, Ross D.
    Groisman, Pavel Ya
    Labba, Niklas
    Radionov, Vladimir
    Bradley, Raymond S.
    Blangy, Sylvie
    Bulygina, Olga N.
    Christensen, Torben R.
    Colman, Jonathan E.
    Essery, Richard L. H.
    Forbes, Bruce C.
    Forchhammer, Mads C.
    Golubev, Vladimir N.
    Honrath, Richard E.
    Juday, Glenn P.
    Meshcherskaya, Anna V.
    Phoenix, Gareth K.
    Pomeroy, John
    Rautio, Arja
    Robinson, David A.
    Schmidt, Niels M.
    Serreze, Mark C.
    Shevchenko, Vladimir P.
    Shiklomanov, Alexander I.
    Shmakin, Andrey B.
    Sköld, Peter
    Umeå University, Arctic Research Centre at Umeå University. Umeå University, Faculty of Arts, Centre for Sami Research.
    Sturm, Matthew
    Woo, Ming-ko
    Wood, Eric F.
    Multiple effects of changes in arctic snow cover2011In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 40, p. 32-45Article in journal (Refereed)
    Abstract [en]

    Snow cover plays a major role in the climate, hydrological and ecological systems of the Arctic and other regions through its influence on the surface energy balance (e.g. reflectivity), water balance (e.g. water storage and release), thermal regimes (e.g. insulation), vegetation and trace gas fluxes. Feedbacks to the climate system have global consequences. The livelihoods and well-being of Arctic residents and many services for the wider population depend on snow conditions so changes have important consequences. Already, changing snow conditions, particularly reduced summer soil moisture, winter thaw events and rain-on-snow conditions have negatively affected commercial forestry, reindeer herding, some wild animal populations and vegetation. Reductions in snow cover are also adversely impacting indigenous peoples' access to traditional foods with negative impacts on human health and well-being. However, there are likely to be some benefits from a changing Arctic snow regime such as more even run-off from melting snow that favours hydropower operations.

  • 257. Cameron, Erin K.
    et al.
    Sundqvist, Maja K.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. The Center for Macroecology, Evolution and Climate, The Natural History Museum of Denmark, University of Copenhagen,Universitetsparken 15, 2100 Copenhagen Ø, Denmark.
    Keith, Sally A.
    CaraDonna, Paul J.
    Mousing, Erik A.
    Nilsson, Karin A.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Metcalfe, Daniel B.
    Classen, Aimee T.
    Uneven global distribution of food web studies under climate change2019In: Ecosphere, ISSN 2150-8925, E-ISSN 2150-8925, Vol. 10, no 3, article id e02645Article in journal (Refereed)
    Abstract [en]

    Trophic interactions within food webs affect species distributions, coexistence, and provision of ecosystem services but can be strongly impacted by climatic changes. Understanding these impacts is therefore essential for managing ecosystems and sustaining human well-being. Here, we conducted a global synthesis of terrestrial, marine, and freshwater studies to identify key gaps in our knowledge of climate change impacts on food webs and determine whether the areas currently studied are those most likely to be impacted by climate change. We found research suffers from a strong geographic bias, with only 3.5% of studies occurring in the tropics. Importantly, the distribution of sites sampled under projected climate changes was biased-areas with decreases or large increases in precipitation and areas with low magnitudes of temperature change were under-represented. Our results suggest that understanding of climate change impacts on food webs could be broadened by considering more than two trophic levels, responses in addition to species abundance and biomass, impacts of a wider suite of climatic variables, and tropical ecosystems. Most importantly, to enable better forecasts of biodiversity responses to dimate change, we identify critically under-represented geographic regions and climatic conditions which should be prioritized in future research.

  • 258.
    Cameron, Thomas C.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Univ Leeds, Inst Integrat & Comparat Biol, Ecol & Evolut Res Grp, Leeds LS2 9JT, W Yorkshire, England.
    O'Sullivan, Daniel
    Reynolds, Alan
    Piertney, Stuart B.
    Benton, Tim G.
    Eco-evolutionary dynamics in response to selection on life-history2013In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 16, no 6, p. 754-763Article in journal (Refereed)
    Abstract [en]

    Understanding the consequences of environmental change on ecological and evolutionary dynamics is inherently problematic because of the complex interplay between them. Using invertebrates in microcosms, we characterise phenotypic, population and evolutionary dynamics before, during and after exposure to a novel environment and harvesting over 20 generations. We demonstrate an evolved change in life-history traits (the age- and size-at-maturity, and survival to maturity) in response to selection caused by environmental change (wild to laboratory) and to harvesting (juvenile or adult). Life-history evolution, which drives changes in population growth rate and thus population dynamics, includes an increase in age-to-maturity of 76% (from 12.5 to 22days) in the unharvested populations as they adapt to the new environment. Evolutionary responses to harvesting are outweighed by the response to environmental change (similar to 1.4 vs. 4% change in age-at-maturity per generation). The adaptive response to environmental change converts a negative population growth trajectory into a positive one: an example of evolutionary rescue.

  • 259. Campeau, Audrey
    et al.
    Wallin, Marcus B.
    Giesler, Reiner
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Löfgren, Stefan
    Mörth, Carl-Magnus
    Schiff, Sherry
    Venkiteswaran, Jason J.
    Bishop, Kevin
    Multiple sources and sinks of dissolved inorganic carbon across Swedish streams, refocusing the lens of stable C isotopes2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 9158Article in journal (Refereed)
    Abstract [en]

    It is well established that stream dissolved inorganic carbon (DIC) fluxes play a central role in the global C cycle, yet the sources of stream DIC remain to a large extent unresolved. Here, we explore large-scale patterns in δ13C-DIC from streams across Sweden to separate and further quantify the sources and sinks of stream DIC. We found that stream DIC is governed by a variety of sources and sinks including biogenic and geogenic sources, CO2 evasion, as well as in-stream processes. Although soil respiration was the main source of DIC across all streams, a geogenic DIC influence was identified in the northernmost region. All streams were affected by various degrees of atmospheric CO2 evasion, but residual variance in δ13C-DIC also indicated a significant influence of in-stream metabolism and anaerobic processes. Due to those multiple sources and sinks, we emphasize that simply quantifying aquatic DIC fluxes will not be sufficient to characterise their role in the global C cycle.

  • 260.
    Capel, Mégane
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Environmental change during the Holocene: A comparative multi-proxy study of landscape disturbances in Northern Sweden2019Independent thesis Advanced level (degree of Master (Two Years)), 40 credits / 60 HE creditsStudent thesis
    Abstract [en]

    Varved lake sediments were used to provide information on how a landscape is affected by disturbances of different scales, from global (i.e. climatic) to local (i.e. fires), as well as anthropogenic activities. Geochemical and pollen data, biogenic silica (bSi), lake-water total organic carbon (LWTOC) and chlorophyll a were used as proxies to infer past changes in lake-conditions. The goal was to evaluate the response to scale different disturbances and how it differs among sites. By comparing different lake records, it became possible to isolate the climatic signal from the effect of soil development and vegetation establishment, and differences emerging from different catchment characteristics. Climatic trends were reconstructed based on the pollen and geochemical data. The sediment records were then compared to identify the effect of each disturbance on individual lakes. One of the most prominent event observed was the immigration of spruce at about 3000 BP which considerably affected sedimentation trends. The presence of spruce within the catchment appears to promote the input of fine-grained material to the lakes. The timing and intensification of anthropogenic activities was established and it was possible to differentiate the effects of human disturbance from changes caused by natural processes such as climate or landscape vegetation cover changes. The results show that farming practices started earlier in more southern locations and that this timing is site-dependent. Two phases were identified, corresponding to the start of slash and burn farming and later to the expansion of agricultural practices, with a more profound transformation of the landscape.

  • 261.
    Capo, Eric
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Rydberg, Johan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Tolu, Julie
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland.
    Domaizon, Isabelle
    Debroas, Didier
    Bindler, Richard
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Bigler, Christian
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    How Does Environmental Inter-annual Variability Shape Aquatic Microbial Communities?: A 40-Year Annual Record of Sedimentary DNA From a Boreal Lake (Nylandssjon, Sweden)2019In: Frontiers in Ecology and Evolution, E-ISSN 2296-701X, Vol. 7, article id 245Article in journal (Refereed)
    Abstract [en]

    To assess the sensitivity of lakes to anthropogenically-driven environmental changes (e.g., nutrient supply, climate change), it is necessary to first isolate the effects of between-year variability in weather conditions. This variability can strongly impact a lake's biological community especially in boreal and arctic areas where snow phenology play an important role in controlling the input of terrestrial matter to the lake. Identifying the importance of this inherent variability is difficult without time series that span at least several decades. Here, we applied a molecular approach (metabarcoding on eukaryotic 18S rRNA genes and qPCR on cyanobacterial 16S rRNA genes) to sedimentary DNA (sed-DNA) to unravel the annual variability of microbial community in 40 years' sediment record from the boreal lake Nylandssjon which preserve annually-laminated sediments. Our comparison between seasonal meteorological data, sediment inorganic geochemistry (X-ray fluorescence analyses) and organic biomarkers (pyrolysis-gas chromatography/mass spectrometry analyses), demonstrated that inter-annual variability strongly influence the sediment composition in Nylandssjon. Spring temperature, snow and ice phenology (e.g., the percentage of snow loss in spring, the timing of lake ice-off) were identified as important drivers for the inputs of terrestrial material to the lake, and were therefore also important for shaping the aquatic biological community. Main changes were detected in the late-80s/mid-90s and mid-2000s associated with increases in algal productivity, in total richness of the protistan community and in relative abundances of Chlorophyta, Dinophyceae as well as Cyanobacteria abundance. These changes could be linked to a decline in terrestrial inputs to the lake during the snow melt and run-off period, which in turn was driven by warmer winter temperatures. Even if our data shows that meteorological factors do affect the sediment composition and microbial communities, they only explain part of the variability. This is most likely a consequence of the high inter-annual variability in abiotic and biotic parameters highlighting the difficulty to draw firm conclusions concerning drivers of biological changes at an annual or sub-annual resolution even with the 40-year varved sediment record from Nylandssjon. Hence, it is necessary to have an even longer time perspective in order to reveal the full implications of climate change.

  • 262. Carlsson, Fredrik
    et al.
    Lampi, Elina
    Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE), Economics.
    Martinsson, Peter
    The marginal values of noise disturbance from air traffic: does the time of the day matter?2004In: Transportation Research Part D: Transport and Environment, ISSN 1361-9209, E-ISSN 1879-2340, Vol. 9, no 5, p. 373-385Article in journal (Refereed)
    Abstract [en]

    This paper analyzes the marginal willingness to pay for changes in noise levels related to changes in the volume of flight movements at a city airport in Stockholm, Sweden, by using a choice experiment. When estimating marginal willingness to pay for different times of the day and days of the week, we find that these vary with the temporal dimensions: mornings and evenings have higher marginal values. Interestingly, a substantial proportion of the respondents prefer no changes in the current noise level. The paper concludes with a policy discussion related to incentive-based pricing.

  • 263.
    Carlsson-Graner, Ulla
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Giles, Barbara
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Thrall, P. H.
    Centre for Plant Biodiversity Research, CSIRO - Plant Industry, GPO Box 1600, Canberra, ACT, 2601, Australia.
    Patterns of disease and host resistance in spatially structured systems2014In: European journal of plant pathology, ISSN 0929-1873, E-ISSN 1573-8469, Vol. 138, no 3, p. 499-511Article in journal (Refereed)
    Abstract [en]

    We use data from species of the anther-smut fungi and the host plants Lychnis alpina and Silene dioica to show that spatial structuring at different scales can influence patterns of disease and host resistance. Patterns of disease and host resistance were surveyed in an archipelago subject to land-uplift where populations of S. dioica constitute an age-structured metapopulation, and in three contrasting areas within the mainland range of L. alpina, where population distributions range from continuous, through patchy but spatially connected to highly isolated demes. In S. dioica, disease levels depend on the age, size and density of local patches and populations. Disease is most predictably found in larger dense host patches and populations of intermediate age, and more frequently goes extinct in small old populations. The rate of local disease spread is affected by the level of host resistance; S. dioica populations showing an increase in disease over time are more susceptible than populations where the disease has remained at low levels. Among-population variation in resistance is driven by founding events and populations remain differentiated due to limited gene flow between islands. As observed in the L. alpina system, when populations are more connected, a greater fraction of populations have disease present. Results from a simulation model argue that, while increased dispersal in connected systems can increase disease spread, it may also favour selection of host resistance which ultimately reduces disease levels within populations. This could explain the observed lower disease prevalence in L. alpina in regions where populations are more continuous.

  • 264. Carr, Joel A.
    et al.
    D'Odorico, Paolo
    Suweis, Samir
    Seekell, David A.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    What commodities and countries impact inequality in the global food system?2016In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 11, no 9, article id 095013Article in journal (Refereed)
    Abstract [en]

    The global distribution of food production is unequal relative to the distribution of human populations. International trade can increase or decrease inequality in food availability, but little is known about how specific countries and commodities contribute to this redistribution. We present a method based on the Gini coefficient for evaluating the contributions of country and commodity specific trade to inequality in the global food system. We applied the method to global food production and trade data for the years 1986-2011 to identify the specific countries and commodities that contribute to increasing and decreasing inequality in global food availability relative to food production. Overall, international trade reduced inequality in food availability by 25%-33% relative to the distribution of food production, depending on the year. Across all years, about 58% of the total trade links acted to reduce inequality with similar to 4% of the links providing 95% of the reduction in inequality. Exports from United States of America, Malaysia, Argentina, and Canada are particularly important in decreasing inequality. Specific commodities that reduce inequality when traded include cereals and vegetables. Some trade connections contribute to increasing inequality, but this effect is mostly concentrated within a small number of commodities including fruits, stimulants, and nuts. In terms of specific countries, exports from Slovenia, Oman, Singapore, and Germany act to increase overall inequality. Collectively, our analysis and results represent an opportunity for building an enhanced understanding of global-scale patterns in food availability.

  • 265.
    Carvalho, Ricardo L.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Centre for Environmental and Marine Studies, Dept. of Environment and Planning, University of Aveiro, Aveiro, Portugal; Laboratory of Renewable Energy and Environmental Comfort, Institute of Education, Science and Technology of Ceará, Fortaleza, Brazil.
    Lindgren, Robert
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Lopez, N.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Nyambane, Anne
    Nyberg, Gert
    Diaz-Chavez, Rocio
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Household air pollution mitigation with integrated biomass/cookstove strategies in Western Kenya2019In: Energy Policy, ISSN 0301-4215, E-ISSN 1873-6777, Vol. 131, p. 168-186Article in journal (Refereed)
    Abstract [en]

    Traditional cooking is today's largest global environmental health risk. Over 640 million people in Africa are expected to rely on biomass for cooking by 2040. In Kenya, cooking inefficiently with wood and charcoal persists as a cause of deforestation and household air pollution. This research analyses the effects of four biomass cookstove strategies on reducing air pollutant emissions in Kisumu County between 2015 and 2035 using the Long-Range Energy Alternatives Planning system. The Business as Usual scenario (BAU) was developed considering the historical trends in household energy use. Energy transition scenarios to Improved Cookstoves (ICS), Pellet Gasifier Stoves (PGS) and Biogas Stoves (BGS) were applied to examine the impact of these systems on energy savings and air pollution mitigation. An integrated scenario (INT) was evaluated as a mix of the ICS, PGS and BGS. The highest energy savings, in relation to the BAU, are achieved in the BGS (30.9%), followed by the INT (23.5%), PGS (19.4%) and ICS (9.2%). The BGS offers the highest reduction in the GHG (37.6%), CH4 (94.3%), NMVOCs (85.0%), CO (97.4%), PM2.5 (64.7%) and BC (48.4%) emissions, and the PGS the highest reduction in the N2O (83.0%) and NOx (90.7%) emissions, in relation to the BAU.

  • 266. Catalan, Jordi
    et al.
    Pla-Rabes, Sergi
    Wolfe, Alexander P.
    Smol, John P.
    Ruehland, Kathleen M.
    Anderson, N. John
    Kopacek, Jiri
    Stuchlik, Evzen
    Schmidt, Roland
    Koinig, Karin A.
    Camarero, Lluis
    Flower, Roger J.
    Heiri, Oliver
    Kamenik, Christian
    Korhola, Atte
    Leavitt, Peter R.
    Psenner, Roland
    Renberg, Ingemar
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Global change revealed by palaeolimnological records from remote lakes: a review2013In: Journal of Paleolimnology, ISSN 0921-2728, E-ISSN 1573-0417, Vol. 49, no 3, p. 513-535Article in journal (Refereed)
    Abstract [en]

    Over recent decades, palaeolimnological records from remote sites have provided convincing evidence for the onset and development of several facets of global environmental change. Remote lakes, defined here as those occurring in high latitude or high altitude regions, have the advantage of not being overprinted by local anthropogenic processes. As such, many of these sites record broad-scale environmental changes, frequently driven by regime shifts in the Earth system. Here, we review a selection of studies from North America and Europe and discuss their broader implications. The history of investigation has evolved synchronously with the scope and awareness of environmental problems. An initial focus on acid deposition switched to metal and other types of pollutants, then climate change and eventually to atmospheric deposition-fertilising effects. However, none of these topics is independent of the other, and all of them affect ecosystem function and biodiversity in profound ways. Currently, remote lake palaeolimnology is developing unique datasets for each region investigated that benchmark current trends with respect to past, purely natural variability in lake systems. Fostering conceptual and methodological bridges with other environmental disciplines will upturn contribution of remote lake palaeolimnology in solving existing and emerging questions in global change science and planetary stewardship.

  • 267. Catalán, N.
    et al.
    Casas-Ruiz, J. P.
    Arce, M. I.
    Abril, M.
    Bravo, A. G.
    del Campo, R.
    Estévez, E.
    Freixa, A.
    Giménez-Grau, P.
    González-Ferreras, A. M.
    Gómez-Gener, Luís
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Lupon, A.
    Martinez, A.
    Palacin-Lizarbe, C.
    Poblador, S.
    Rasines-Ladero, R.
    Reyes, M.
    Rodriguez-Castillo, T.
    Rodriguez-Lozano, P.
    Sanpera-Calbet, I.
    Tornero, I.
    Pastor, A.
    Behind the Scenes: mechanisms Regulating Climatic Patterns of Dissolved Organic Carbon Uptake in Headwater Streams2018In: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224, Vol. 32, no 10, p. 1528-1541Article in journal (Refereed)
    Abstract [en]

    Large variability in dissolved organic carbon (DOC) uptake rates has been reported for headwater streams, but the causes of this variability are still not well understood. Here we assessed acetate uptake rates across 11 European streams comprising different ecoregions by using whole-reach pulse acetate additions. We evaluated the main climatic and biogeochemical drivers of acetate uptake during two seasonal periods. Our results show a minor influence of sampling periods but a strong effect of climate and dissolved organic matter (DOM) composition on acetate uptake. In particular, mean annual precipitation explained half of the variability of the acetate uptake velocities (Vf(Acetate)) across streams. Temperate streams presented the lowest Vf(Acetate), together with humic-like DOM and the highest stream respiration rates. In contrast, higher Vf(Acetate) were found in semiarid streams, with protein-like DOM, indicating a dominance of reactive, labile compounds. This, together with lower stream respiration rates and molar ratios of DOC to nitrate, suggests a strong C limitation in semiarid streams, likely due to reduced inputs from the catchment. Overall, this study highlights the interplay of climate and DOM composition and its relevance to understand the biogeochemical mechanisms controlling DOC uptake in streams. Plain Language Summary Headwater streams receive and degrade organic carbon and nutrients from the surrounding catchments. That degradation can be assessed by measuring the uptake of simple compounds of carbon or nitrogen such as acetate or nitrate. Here we determine the variability in acetate and nitrate uptake rates across headwater streams and elucidate the mechanisms behind that variability. The balance between nutrients, the composition of the organic materials present in the streams, and the climatic background is at interplay.

  • 268.
    Catford, Jane A.
    et al.
    Department of Resource Management and Geography, The University of Melbourne, Australia.
    Jansson, Roland
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Nilsson, Christer
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Reducing redundancy in invasion ecology by integrating hypotheses into a single theoretical framework2009In: Diversity & distributions: A journal of biological invasions and biodiversity, ISSN 1366-9516, E-ISSN 1472-4642, Vol. 15, no 1, p. 22-40Article in journal (Refereed)
    Abstract [en]

    Aim: Invasion ecology includes many hypotheses. Empirical evidence suggests that most of these can explain the success of some invaders to some degree in some circumstances. If they all are correct, what does this tell us about invasion? We illustrate the major themes in invasion ecology, and provide an overarching framework that helps organize research and foster links among subfields of invasion ecology and ecology more generally.

    Location: Global.

    Methods: We review and synthesize 29 leading hypotheses in plant invasion ecology. Structured around propagule pressure (P), abiotic characteristics (A) and biotic characteristics (B), with the additional influence of humans (H) on P, A and B (hereon PAB), we show how these hypotheses fit into one paradigm. P is based on the size and frequency of introductions, A incorporates ecosystem invasibility based on physical conditions, and B includes the characteristics of invading species (invasiveness), the recipient community and their interactions. Having justified the PAB framework, we propose a way in which invasion research could progress.

    Results: By highlighting the common ground among hypotheses, we show that invasion ecology is encumbered by theoretical redundancy that can be removed through integration. Using both holistic and incremental approaches, we show how the PAB framework can guide research and quantify the relative importance of different invasion mechanisms.

    Main conclusions: If the prime aim is to identify the main cause of invasion success, we contend that a top-down approach that focuses on PAB maximizes research efficiency. This approach identifies the most influential factors first, and subsequently narrows the number of potential causal mechanisms. By viewing invasion as a multifaceted process that can be partitioned into major drivers and broken down into a series of sequential steps, invasion theory can be rigorously tested, understanding improved and effective weed management techniques identified.

  • 269.
    Cañadas Fernandez, Manuel
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Monitoring mercury in an urban environment, Umeå, Sweden: Representability and variability of mercury using forest moss biomonitoring in an urban environment2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The objective of my project was to determine variability and representability of mercury in the urban environment of Umeå in northern Sweden, based on applying the methods of forest moss biomonitoring (Swedish Environmental Protection Agency, ICP Manual). Mercury (Hg) is a commune pollutant in urban environments release to the atmosphere by anthropogenic activities. Industrial, traffic and incineration activities are the main sources of this element. Mercury is easily transported through the atmosphere and cycle through terrestrial and aquatic ecosystems, trending to bioaccumulate in organisms. The aims of the study are: (1) determine the representability and variability of the method in a specific urban environment, based on more intensive analyses of a green area within the city boundaries of Umeå, northern Sweden. (2) influence of site-specific conditions on the concentration of mercury in mosses. (3) City-scale variability in relation to national forest moss biomonitoring data (IVL.se). Results of urban environment measurements do not differ much respect the values of mercury concentration obtained sampling mosses far from the city, but it is subject to many factors that can alter results of the study.  Most of these are meteorological factors and the difficulty of find green zones close to cities with the suitable conditions to find mosses and perform a property sampling process avoiding throughfall and litterfall. The conclusion is that the use of mosses is a representative and valuable method to obtaining information in an urban environment but is limited by mentioned factors.

  • 270.
    Cerveny, Daniel
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. University of South Bohemia in Ceske Budejovice, Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Vodnany, Czech Republic.
    Grabic, Roman
    Fedorova, Ganna
    Grabicova, Katerina
    Turek, Jan
    Zlabek, Vladimir
    Randak, Tomas
    Fate of perfluoroalkyl substances within a small stream food web affected by sewage effluent2018In: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 134, p. 226-233Article in journal (Refereed)
    Abstract [en]

    The fate of fourteen target perfluoroalkyl substances (PFASs) are described within a small stream affected by a sewage treatment plant (STP) effluent. Concentrations of target PFASs in samples of water, benthic macroinvertebrates and brown trout (Salmo trutta) are presented. Two hundred brown trout individuals originating from clean sites within the same stream were tagged and stocked into an experimental site affected by the STP's effluent. As a passive sampling approach, polar organic chemical integrative samplers (POCIS) were deployed in the water to reveal the water-macroinvertebrates-fish biotransformation processes of PFASs. Bioconcentration/bioaccumulation of target compounds was monitored one, three, and six months after stocking. Twelve of the fourteen target PFASs were found in concentration above the LOQ in at least one of the studied matrices. The compound pattern varied significantly between both the studied species and water samples. Concerning the accumulation of PFASs in fish, the highest concentrations were found in the liver of individuals sampled after three months of exposure. These concentrations rapidly decreased after six months although the water concentrations were slightly increasing during experiment.

  • 271. Chahtane, Hicham
    et al.
    Zhang, Bo
    Norberg, Mikael
    LeMasson, Marie
    Thevenon, Emmanuel
    Bakó, László
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Benlloch, Reyes
    Holmlund, Mattias
    Parcy, Francois
    Nilsson, Ove
    Vachon, Gilles
    LEAFY activity is post-transcriptionally regulated by BLADE ON PETIOLE2 and CULLIN3 in Arabidopsis2018In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 220, no 2, p. 579-592Article in journal (Refereed)
    Abstract [en]

    The Arabidopsis LEAFY (LFY) transcription factor is a key regulator of floral meristem emergence and identity. LFY interacts genetically and physically with UNUSUAL FLORAL ORGANS, a substrate adaptor of CULLIN1-RING ubiquitin ligase complexes (CRL1). The functionally redundant genes BLADE ON PETIOLE1 (BOP1) and -2 (BOP2) are potential candidates to regulate LFY activity and have recently been shown to be substrate adaptors of CULLIN3 (CUL3)-RING ubiquitin ligases (CRL3). We tested the hypothesis that LFY activity is controlled by BOPs and CUL3s in plants and that LFY is a substrate for ubiquitination by BOP-containing CRL3 complexes. When constitutively expressed, LFY activity is fully dependent on BOP2 as well as on CUL3A and B to regulate target genes such as APETALA1 and to induce ectopic flower formation. We also show that LFY and BOP2 proteins interact physically and that LFY-dependent ubiquitinated species are produced invitro in a reconstituted cell-free CRL3 system in the presence of LFY, BOP2 and CUL3. This new post-translational regulation of LFY activity by CRL3 complexes makes it a unique transcription factor subjected to a positive dual regulation by both CRL1 and CRL3 complexes and suggests a novel mechanism for promoting flower development.

  • 272. Chambers, Frank M.
    et al.
    Booth, Robert K.
    De Vleeschouwer, Francois
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Lamentowicz, Mariusz
    Le Roux, Gael
    Mauquoy, Dmitri
    Nichols, Jonathan E.
    van Geel, Bas
    Development and refinement of proxy-climate indicators from peats2012In: Quaternary International, ISSN 1040-6182, E-ISSN 1873-4553, Vol. 268, p. 21-33Article in journal (Refereed)
    Abstract [en]

    Peat, especially from acidic mires (bogs), is a natural archive of past environmental change. Reconstructions of past climate from bogs commenced in the 19th Century through examination of visible peat stratigraphy, and later formed the basis for a postglacial climatic scheme widely used in Northwest Europe. Nevertheless, misconceptions as to how bogs grow led to a 50-year lacuna in peat-climate study, before the concept of 'cyclic regeneration' in bogs was refuted. In recent decades, research using proxy-climate indicators from bogs has burgeoned. A range of proxies for past hydrological change has been developed, as well as use of pollen, bog oaks and pines and other data to reconstruct past temperatures. Most of this proxy-climate research has been carried out in Northern Europe, but peat-based research in parts of Asia and North America has increased, particularly during the last decade, while research has also been conducted in Australia, New Zealand and South America. This paper reviews developments in proxy-climate reconstructions from peatlands; chronicles use of a range of palaeo-proxies such as visible peat stratigraphy, plant macrofossils, peat humification, testate amoebae and non-pollen palynomorphs: and explains the use of wiggle-match radiocarbon dating and relationship to climate shifts. It details other techniques being used increasingly, such as biomarkers, stable-isotopes, inorganic geochemistry and estimation of dust flux: and points to new proxies under development. Although explicit protocols have been developed recently for research on ombrotrophic mires, it must be recognised that not all proxies and techniques have universal applicability, owing to differences in species assemblages, mire formation, topographic controls, and geochemical characteristics. (C) 2011 Elsevier Ltd and INQUA. All rights reserved.

  • 273. Chapligin, B
    et al.
    Meyer, H
    Swann, GEA
    Meyer-Jacob, Carsten
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Hubberten, H-W
    A 250 ka oxygen isotope record from diatoms at Lake El'gygytgyn, far east Russian Arctic2012In: Climate of the Past, ISSN 1814-9324, E-ISSN 1814-9332, Vol. 8, no 5, p. 1621-1636Article in journal (Refereed)
    Abstract [en]

    In 2003 sediment core Lz1024 was drilled at Lake El'gygytgyn, far east Russian Arctic, in an area of the Northern Hemisphere which has not been glaciated for the last 3.6 Ma. Biogenic silica was used for analysing the oxygen isotope composition (delta O-18(diatom)) in the upper 13m long section dating back about 250 ka with samples dominated by one taxa in the < 10 mu m fraction (Cyclotella ocellata). Downcore variations in delta O-18 values show that glacial-interglacial cycles are present throughout the core and delta O-18(diatom)-values are mainly controlled by delta O-18(precipitation). Changes reflect the Holocene Thermal Maximum, the Last Glacial Maximum (LGM) and the interglacial periods corresponding to MIS 5.5 and MIS 7 with a peak-to-peak amplitude between LGM and MIS 5.5 of Delta O-18=5.3 parts per thousand. This corresponds to a mean annual air temperature difference of about 9 degrees C. Our record is the first continuous delta O-18(diatom) record from an Arctic lake sediment core directly responding to precipitation and dating back more than 250 ka and correlates well with the stacked marine delta(18)OLR04 (r = 0.58) and delta D EPICA Dome-C record (r = 0.69). With delta O-18 results indicating strong links to both marine and ice-core records, records from Lake El'gygytgyn can be used to further investigate the sensitivity of the Arctic climate to both past and future global climatic changes.

  • 274.
    Chen, Keyao
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Influence of depositional mobility (downwashing) on the accumulation of atmospherically supplied elements in peat cores: an experimental approach2014Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    The potential influence of downwashing on atmospherically deposited elements is of rare focus compared with other geochemical processes related to peat. Downwashing may cause a rapid downward movement of atmospherically supplied elements before they bond to the peat organic substrate and thus reduce the reliability of age-depth models that rely on atmospherically supplied radioisotopes (e.g. 210Pb, 241Am, 137Cs). However, the existence of downwashing has not been directly tested, and to which depth the deposited element can be washed down is not fully understood. To address the question of downwashing, an experiment was set up to mimic wet deposition by applying a CuBr2 solution during a three-week period in peat cores collected from Rödmossamyran. Through this, the experimental results clearly supported the existence of downward mobility. Added Cu2+ could be measured to a depth of 10 cm, similar to previous studies based on Be and Pb. As a similar metal to Cu, the age-depth model based on 210Pb dating could underestimate the ages to some extent without consideration of downwashing.

  • 275.
    Cheng, Wei
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Hanna, K.
    Boily, Jean-Francois
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Water Vapor Binding on Organic Matter-Coated Minerals2019In: Environmental Science & Technology, ISSN 0013-936X, Vol. 53, no 3, p. 1252-1257Article in journal (Refereed)
    Abstract [en]

    Atmospheric water vapor binding to soils is a key process driving water availability in unsaturated terrestrial environments. Using a representative hydrophilic iron oxyhydroxide, this study highlights key mechanisms through which water vapor (i) adsorbs and (ii) condenses at mineral surfaces coated with Leonardite humic acid (LHA). Microgravimetry and vibrational spectroscopy showed that liquid-like water forms in the three-dimensional array of mineral-bound LHA when present at total C/Fe ratios well exceeding similar to 73 mg C per g Fe (26 C atoms/nm(2)). Below these loadings, minerals become even less hydrophilic than in the absence of LHA. This lowering in hydrophilicity is caused by the complexation of LHA water-binding sites to mineral surfaces, and possibly by conformational changes in LHA structure removing available condensation environments for water. An empirical relationship predicting the dependence of water adsorption densities on LHA loadings was developed from these results. Together with the molecular-level description provided in this work, this relationship should guide efforts in predicting water availability, and thereby occurrences of water-driven geochemical processes in terrestrial environments.

  • 276.
    Cherif, Mehdi
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Loreau, Michel
    Plant - herbivore -decomposer stoichiometric mismatches and nutrientcycling in ecosystems2013In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 280, no 1754, p. 20122453-Article in journal (Refereed)
    Abstract [en]

    Plant stoichiometry is thought to have a major influence on how herbivores affect nutrient availability in ecosystems. Most conceptual models predict that plants with high nutrient contents increase nutrient excretion by herbivores, in turn raising nutrient availability. To test this hypothesis, we built a stoichiometrically explicit model that includes a simple but thorough description of the processes of herbivory and decomposition. Our results challenge traditional views of herbivore impacts on nutrient availability in many ways. They show that the relationship between plant nutrient content and the impact of herbivores predicted by conceptual models holds only at high plant nutrient contents. At low plant nutrient contents, the impact of herbivores is mediated by the mineralization/immobilization of nutrients by decomposers and by the type of resource limiting the growth of decomposers. Both parameters are functions of the mismatch between plant and decomposer stoichiometries. Our work provides new predictions about the impacts of herbivores on ecosystemfertility that depend on critical interactions between plant, herbivore and decomposer stoichiometries in ecosystems.

  • 277. Cioffi, Francesco
    et al.
    Lall, Upmanu
    Rus, Ester
    Krishnamurthy, Chandra Kiran B.
    Umeå University, Faculty of Social Sciences, Center for Environmental and Resource Economics (CERE). Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE), Economics.
    Space-time structure of extreme precipitation in Europe over the last century2015In: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088, Vol. 35, no 8, p. 1749-1760Article in journal (Refereed)
    Abstract [en]

    We investigate the space-time structure of extreme precipitation in Europe over the last century, using daily rainfall data from the European Climate Assessment & Dataset (ECA&D) archive. The database includes 267 stations with records longer than 100 years. In the winter season (October to March), for each station, two classes of daily rainfall amount values are selected that, respectively, exceed the 90th and 95th percentile of daily rainfall amount over all the 100 years. For each class, and at each location, an annual time series of the frequency of exceedance and of the total precipitation, defined respectively as the number of days the rainfall threshold (90th and 95th percentiles) is exceeded and total precipitation on days when the percentile is exceeded, are developed. Space-time structure of the frequency and total precipitation time series at the different locations are then pursued using multivariate time and frequency domain methods. The identified key trends and organized spectral modes are linked to well-known climate indices, as North Atlantic Oscillation (NAO) and El Nino Southern Oscillation (ENSO). The spectra of the leading principal component of frequency of exceedance and of total precipitation have a peak with a 5-year period that is significant at the 5% level. These are also significantly correlated with ENSO series with this period. The spectrum of total rainfall is significant at the 10% level with a period of similar to 8 years. This appears to be significantly correlated to the NAO index at this period. Thus, a decomposition of both secular trends and quasi-periodic behaviour in extreme daily rainfall is provided.

  • 278.
    Classen, Neele
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    1000 years of environmental changes in Falun, Sweden: Lake Sediment as source material2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim of this study was to get a better knowledge of the metal pollution and the mining

    history of the Falun area. It adds new information on the geochemistry of the lakes and the

    beginning of mining in the Falun region, together with the influence of early land use. The

    main focus is on three lakes Hagtjärnen, Stugutjärnen and Nästjärnen, which were previously

    dated and analyzed regarding acidification by Anna Ek. Additional supporting information is

    provided from records from 10 other lakes, which are located at distances between 0-27 km

    from the Falun Copper mine. Another specific focus is on the lake Tisken, which has been

    assumed over the past 50 years to represent faithful historical record of mining in the Falun

    area. In this study this lake record was dated and analyzed, too. The analyses of all the lakes

    included resulted in four significant phases of environmental change, indicating the start of

    agriculture and mining, the development of each sector, as well as the sharp increase in

    pollution in the modern time period. Phase I covers the time period A.D. 700-1000 and

    represents the time of the early beginning of land use and small scale mining activities. Phase

    II represents the time between A.D. 1200 to 1450, which is dominated by an ongoing

    development of mining and a sharp increase in metal concentrations and occurrence of

    cultivated plants and plants favored by disturbance from A.D. 1450 onwards. The third phase,

    representing the year A.D. 1540, clearly displays another period of sharp increases among the

    metal concentrations, which coincides with a peak in Cu production volumes. Phase IV

    covers the time period A.D. 1750-1900, referred to as Modern time, and features a clear

    increase in Pb pollution, which is linked to the introduction of tetra ethyl Pb in the 1970s.

    Other metals increase also, together with cultivated plants like cereals, indicating an ongoing

    expansion of mining and agriculture. The results also indicate that Cu was not emitted as far

    as other elements, like for example Pb, which led to great pollution only in the lakes close to

    the Falun mine.

    Another important finding is that the lake Tisken does not represent a continual historical

    record, because the sediment is not a chronological sequence and instead likely represents

    mostly a catastrophic input of debris of mixed age. The C-14 dating shows, that the sediment

    is mixed and disturbed in Tisken. As a consequence, the long-standing interpretation of

    Tisken’s sediment record as an archive for the historical start and late development of mining

    at the Falun copper mine is incorrect

  • 279. Codling, Garry
    et al.
    Halsall, Crispin
    Ahrens, Lutz
    Del Vento, Sabino
    Wiberg, Karin
    Bergknut, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Laudon, Hjalmar
    Ebinghaus, Ralf
    The fate of per- and polyfluoroalkyl substances within a melting snowpack of a boreal forest2014In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 191, p. 190-198Article in journal (Refereed)
    Abstract [en]

    Per- and polyfluoroallcyl substances (PFAS) were measured systematically in a snowpack in northern Sweden to determine chemical behaviour during seasonal melt. Average PFAS concentrations were generally low, but displayed a wide range with median (range) concentrations of PFOA and PFOS of 66.5 pg L-1 (ND-122) and 20.5 pg L-1 (2.60-253) respectively. Average concentrations of the shorter chain, C4 and C5 perfluoroalkyl carboxylates (PFCAs) and perfluoroalkyl sulfonates (PFSAs), were similar to 10-fold higher. Differences in the PFAS concentrations and profile were observed between surface snow and deeper layers, with evidence of PFAS migration to deeper snow layers as melt progressed. Chemical loads (ng m(-2)) for C4-9 PFCAs decreased gradually as melt progressed, but increased for C-4, C6-8 PFSAs and the longer chain C10-12 PFCAs. This enrichment in the diminishing snowpack is an unusual phenomenon that will affect PFAS elution with meltwater and subsequent entry to catchment surface waters. (C) 2014 Elsevier Ltd. All rights reserved.

  • 280. Colla, Christopher A.
    et al.
    Casey, William H.
    Ohlin, C. André
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Computational prediction of Mg-isotope fractionation between aqueous [Mg(OH2)6]2+ and brucite2018In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 227, p. 64-74Article in journal (Refereed)
    Abstract [en]

    The fractionation factor in the magnesium-isotope fractionation between aqueous solutions of magnesium and brucite changes sign with increasing temperature, as uncovered by recent experiments. To understand this behavior, the Reduced Partition Function Ratios and isotopic fractionation factors (Δ26/24Mgbrucite-Mg(aq)) are calculated using molecular models of aqueous [Mg(OH2)6]2+ and the mineral brucite at increasing levels of density functional theory. The calculations were carried out on the [Mg(OH2)6]2+·12H2O cluster, along with different Pauling-bond-strength-conserving models of the mineral lattice of brucite. Three conclusions were reached: (i) all levels of theory overestimate 〈Mg‒O〉 bond distances in the aqua ion complex relative to Tutton’s salts; (ii) the calculations predict that brucite at 298.15 K is always enriched in the heavy isotope, in contrast with experimental observations; (iii) the temperature dependencies of Wimpenny et al. (2014) and Li et al. (2014) could only be achieved by fixing the 〈Mg‒O〉 bond distances in the [Mg(OH2)6]2+·12H2O cluster to values close to those observed in crystals that trap the hydrated ion.

  • 281.
    Coria, Jessica
    et al.
    University of Gothenburg.
    Jaraite, Jurate
    Umeå University, Faculty of Social Sciences, Centre for Environmental and Resource Economics (CERE). Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE).
    Transaction Costs of Upstream Versus Downstream Pricing of CO2 Emissions2019In: Environmental and Resource Economics, ISSN 0924-6460, E-ISSN 1573-1502, Vol. 72, no 4, p. 965-1001Article in journal (Refereed)
    Abstract [en]

    To the best of our knowledge, this is the first paper comparing empirically the transaction costs of the monitoring, reporting and verification (MRV) required by two environmental regulations aimed to cost-efficiently reduce greenhouse gas emissions: a carbon dioxide (CO2) tax and an emissions trading system. We do this in the case of Sweden, where a set of firms are covered by both types of regulations—the Swedish CO2 tax and the European Union’s Emissions Trading System (EU ETS). Our results indicate that there is a significant degree of heterogeneity in the transaction costs of the firms in our sample. Moreover, for some of the firms, the transaction costs are high when compared with the actual cost of the CO2 tax and the price of the EU ETS. Furthermore, we find that the MRV costs are lower for CO2 taxation than for the EU ETS, which confirms the general view that regulating emissions upstream via a CO2 tax yields lower transaction costs vis-á-vis downstream regulation via emissions trading.

  • 282. Cormier, Marc-André
    et al.
    Werner, Roland A.
    Sauer, Peter E.
    Gröcke, Darren R.
    Leuenberger, Markus C.
    Wieloch, Thomas
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Schleucher, Jürgen
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Kahmen, Ansgar
    2H-fractionations during the biosynthesis of carbohydrates and lipids imprint a metabolic signal on the δ2H values of plant organic compounds2018In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 218, no 2, p. 479-491Article in journal (Refereed)
    Abstract [en]

    Hydrogen (H) isotope ratio (δ2H) analyses of plant organic compounds have been applied to assess ecohydrological processes in the environment despite a large part of the δ2H variability observed in plant compounds not being fully elucidated.

    We present a conceptual biochemical model based on empirical H isotope data that we generated in two complementary experiments that clarifies a large part of the unexplained variability in the δ2H values of plant organic compounds.

    The experiments demonstrate that information recorded in the δ2H values of plant organic compounds goes beyond hydrological signals and can also contain important information on the carbon and energy metabolism of plants. Our model explains where 2H‐fractionations occur in the biosynthesis of plant organic compounds and how these 2H‐fractionations are tightly coupled to a plant's carbon and energy metabolism. Our model also provides a mechanistic basis to introduce H isotopes in plant organic compounds as a new metabolic proxy for the carbon and energy metabolism of plants and ecosystems.

    Such a new metabolic proxy has the potential to be applied in a broad range of disciplines, including plant and ecosystem physiology, biogeochemistry and palaeoecology.

  • 283. Creed, Irena F.
    et al.
    Bergström, Ann-Kristin
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Trick, Charles G.
    Grimm, Nancy B.
    Hessen, Dag O.
    Karlsson, Jan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Kidd, Karen A.
    Kritzberg, Emma
    McKnight, Diane M.
    Freeman, Erika C.
    Senar, Oscar E.
    Andersson, Agneta
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Ask, Jenny
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Berggren, Martin
    Cherif, Mehdi
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Giesler, Reiner
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Hotchkiss, Erin R.
    Kortelainen, Pirkko
    Palta, Monica M.
    Vrede, Tobias
    Weyhenmeyer, Gesa A.
    Global change-driven effects on dissolved organic matter composition: Implications for food webs of northern lakes2018In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 24, no 8, p. 3692-3714Article, review/survey (Refereed)
    Abstract [en]

    Northern ecosystems are experiencing some of the most dramatic impacts of global change on Earth. Rising temperatures, hydrological intensification, changes in atmospheric acid deposition and associated acidification recovery, and changes in vegetative cover are resulting in fundamental changes in terrestrial-aquatic biogeochemical linkages. The effects of global change are readily observed in alterations in the supply of dissolved organic matter (DOM)-the messenger between terrestrial and lake ecosystems-with potentially profound effects on the structure and function of lakes. Northern terrestrial ecosystems contain substantial stores of organic matter and filter or funnel DOM, affecting the timing and magnitude of DOM delivery to surface waters. This terrestrial DOM is processed in streams, rivers, and lakes, ultimately shifting its composition, stoichiometry, and bioavailability. Here, we explore the potential consequences of these global change-driven effects for lake food webs at northern latitudes. Notably, we provide evidence that increased allochthonous DOM supply to lakes is overwhelming increased autochthonous DOM supply that potentially results from earlier ice-out and a longer growing season. Furthermore, we assess the potential implications of this shift for the nutritional quality of autotrophs in terms of their stoichiometry, fatty acid composition, toxin production, and methylmercury concentration, and therefore, contaminant transfer through the food web. We conclude that global change in northern regions leads not only to reduced primary productivity but also to nutritionally poorer lake food webs, with discernible consequences for the trophic web to fish and humans.

  • 284. Cui, Qiao-Yu
    et al.
    Gaillard, Marie-Jose
    Lemdahl, Geoffrey
    Sugita, Shinya
    Greisman, Annica
    Jacobson, George L.
    Olsson, Fredrik
    Umeå University, Faculty of Social Sciences, Department of Geography and Economic History, Economic history. Umeå University, Faculty of Social Sciences, Centre for Regional Science (CERUM).
    The role of tree composition in Holocene fire history of the hemiboreal and southern boreal zones of southern Sweden, as revealed by the application of the Landscape Reconstruction Algorithm: Implications for biodiversity and climate-change issues2013In: The Holocene, ISSN 0959-6836, E-ISSN 1477-0911, Vol. 23, no 12, p. 1747-1763Article in journal (Refereed)
    Abstract [en]

    We present a quantitative reconstruction of local forest history at two sites, Stavsakra (hemiboreal zone) and Storasjo (southern boreal zone), in southern Sweden (province of Smaland) to evaluate possible causes of contrasting Holocene fire histories in mid- and late Holocene. The Landscape Reconstruction Algorithm (LRA) is applied to evaluate between-site differences in the relative abundance of deciduous trees and Pinus (pine) and landscape/woodland openness during the Holocene. The LRA estimates of local vegetation abundance are compared with other proxies of local vegetation, that is, plant and beetle remains. The LRA results suggest that Pinus was a major tree taxon in the woodlands of Storasjo during mid- and late Holocene, while Tilia (linden) and Betula (birch) were dominant at Stavsakra. The contrasting fire histories are shown to be strongly related to between-site differences in tree composition during mid-Holocene, 4000-2000 bc in particular. The archaeological/historical and beetle data indicate contrasting land uses from c. 1000 bc (late Bronze Age/early Iron Age), grazing in open Calluna heaths at Stavsakra and woodland grazing at Storasjo. Between-site differences in fire history during late Holocene were likely due to different land-use practices. Between-site differences in tree composition in mid-Holocene are best explained by local climatic and geological/geomorphological differences between the hemiboreal and southern boreal zones of Smaland, which might also be the primary cause of between-site differences in land-use histories during late Holocene. Maintenance of biodiversity at the landscape scale in the study area requires that existing old pine woodlands and Calluna heath are managed with fire and cattle grazing. Further climate warming might lead to higher probabilities of climate-induces fire, in particular in pine-dominated woodlands.

  • 285.
    Cuklev, Filip
    et al.
    Sahlgrenska Academy at the University of Gothenburg, Göteborg, Sweden.
    Kristiansson, Erik
    Sahlgrenska Academy at the University of Gothenburg, Göteborg, Sweden och Chalmers University of Technology and University of Gothenburg, Göteborg, Sweden.
    Fick, Jerker
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Asker, Noomi
    Sahlgrenska Academy at the University of Gothenburg, Göteborg, Sweden och Faculty of Science, University of Gothenburg, Göteborg, Sweden.
    Förlin, Lars
    Faculty of Science, University of Gothenburg, Göteborg, Sweden.
    Larsson, D G Joakim
    Sahlgrenska Academy at the University of Gothenburg, Göteborg, Sweden.
    Diclofenac in fish: blood plasma levels similar to human therapeutic levels affect global hepatic gene expression2011In: Environmental Toxicology and Chemistry, ISSN 0730-7268, E-ISSN 1552-8618, Vol. 30, no 9, p. 2126-2134Article in journal (Refereed)
    Abstract [en]

    Diclofenac is a non-steroidal anti-inflammatory drug frequently found in the aquatic environment. Previous studies have reported histological changes in the liver, kidney and gills of fish at concentrations similar to those measured in treated sewage effluents (approximately 1 µg/L). Analyses or predictions of blood plasma levels in fish allow a direct comparison with human therapeutic plasma levels, and may therefore be used to indicate a risk for pharmacological effects in fish. To relate internal exposure to a pharmacological interaction we investigated global hepatic gene expression together with bioconcentration in blood plasma and liver of rainbow trout (Oncorhynchus mykiss) exposed to waterborne diclofenac. At the highest exposure concentration (81.5 µg/L) the fish plasma concentration reached approximately 88% of the human therapeutic levels (C(max) ) after two weeks. Using an oligonucleotide microarray followed by quantitative PCR we found extensive effects on hepatic gene expression at this concentration, and some genes were found to be regulated down to the lowest concentration tested (1.6 µg/L) corresponding to approximately 1.5% of the human C(max) . Thus, at concentrations detected in European surface waters, diclofenac can affect the expression of multiple genes in exposed fish. Functional analysis of differentially expressed genes revealed effects on biological processes such as inflammation and immune response, in agreement with the mode of action of diclofenac in mammals. In contrast to some previously reported results, the bioconcentration factor was found to be stable (4.02 ± 0.75 for blood plasma and 2.54 ± 0.36 for liver) regardless of the water concentration. Environ. Toxicol. Chem. © 2011 SETAC.

  • 286.
    Cunningham, L.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Vogel, H.
    Wennrich, V.
    Juschus, O.
    Nowaczyk, N.
    Rosen, Peter
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Amplified bioproductivity during Transition IV (332 000-342 000 yr ago): evidence from the geochemical record of Lake El'gygytgyn2013In: Climate of the Past, ISSN 1814-9324, E-ISSN 1814-9332, Vol. 9, no 2, p. 679-686Article in journal (Refereed)
    Abstract [en]

    To date, terrestrial archives of long-term climatic change within the Arctic have widely been restricted to ice cores from Greenland and, more recently, sediments from Lake El'gygytgyn in northeast Arctic Russia. Sediments from this lake contain a paleoclimate record of glacial-interglacial cycles during the last three million years. Low-resolution studies at this lake have suggested that changes observed during Transition IV (the transition from marine isotope stage (MIS) 10 to MIS 9) are of greater amplitude than any observed since. In this study, geochemical parameters are used to infer past climatic conditions thus providing the first high-resolution analyses of Transition IV from a terrestrial Arctic setting. These results demonstrate that a significant shift in climate was subsequently followed by a rapid increase in biogenic silica (BSi) production. Following this sharp increase, bioproductivity remained high, but variable, for over a thousand years. This study reveals differences in the timing and magnitude of change within the ratio of silica to titanium (Si/Ti) and BSi records that would not be apparent in lower resolution studies. This has significant implications for the increasingly common use of Si/Ti data as an alternative to traditional BSi measurements.

  • 287.
    Cunningham, Laura
    et al.
    Umeå University, Faculty of Science and Technology. Climate Impacts Research Centre (CIRC), Umeå University, 98107 Abisko, Sweden.
    Vogel, Hendrik
    Nowaczyk, Norbert
    Wennrich, Volker
    Juschus, Olaf
    Persson, Per
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Rosen, Peter
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Climate Impacts Research Centre (CIRC), Umeå University, 98107 Abisko, Sweden.
    Climatic variability during the last interglacial inferred from geochemical proxies in the Lake El'gygytgyn sediment record2013In: Palaeogeography, Palaeoclimatology, Palaeoecology, ISSN 0031-0182, E-ISSN 1872-616X, Vol. 386, p. 408-414Article in journal (Refereed)
    Abstract [en]

    The Last Interglacial Period (LIP) is often regarded as a good analogue for potential climatic conditions under predicted global warming scenarios. Despite this, there is still debate over the nature, duration and frequency of climatic changes during this period. One particularly contentious issue has been the apparent evidence of climatic instability identified in many marine cores but seemingly lacking from many terrestrial archives, especially within the Arctic, a key region for global climate change research. In this paper, geochemical records from Lake El'gygytgyn, north-eastern Russia, are used to infer past climatic changes during the LIP from within the high Arctic. With a sampling resolution of similar to 20-similar to 90 years, these records offer the potential for detailed, high-resolution palaeoclimate reconstruction. This study shows that the LIP commenced in central Chukotka similar to 129 thousand years ago (ka), with the warmest climatic conditions occurring between similar to 128 and 127 ka before being interrupted by a short-lived cold reversal. Mild climatic conditions then persisted until similar to 122 ka when a marked reduction in the sedimentation rate suggests a decrease in precipitation. A further climatic deterioration at similar to 118 ka marks the return to glacial conditions. This study highlights the value of incorporating several geochemical proxies when inferring past climatic conditions, thus providing the potential to identify signals related to environmental change within the catchment. We also demonstrate the importance of considering how changes in sedimentation rate influence proxy records, in order to develop robust palaeoenvironmental reconstructions. (C) 2013 Elsevier B.V. All rights reserved.

  • 288.
    Dahlbäck, Björn
    et al.
    Swedish Polar Research Secretariat.
    van der Watt, Lize-Marié
    Swedish Polar Research Secretariat.
    Jagodziński, Kamil
    Arctic Centre, University of Lapland.
    Kankaanpää, Paula
    Arctic Centre, University of Lapland.
    European Arctic Initiatives Compendium: Preparatory Action, Strategic Environmental Impact Assessment of development of the Arctic2014Report (Other academic)
  • 289.
    Dahlgren, Jonas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Oksanen, Lauri
    Department of Biology, Section of Ecology, University of Turku, Turku, Finland.
    Oksanen, Tarja
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Olofsson, Johan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Hambäck, Peter A
    Department of Botany, Stockholm University, Stockholm, Sweden.
    Lindgren, Åsa
    Department of Botany, Stockholm University, Stockholm, Sweden.
    Plant defences to no avail?: Responses of plants of varying edibility to food web manipulations in a low arctic scrubland2009In: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 11, p. 1189-1203Article in journal (Refereed)
    Abstract [en]

    Background: According to the Green World Hypothesis of Hairston, Smith, and Slobodkin,all plants are edible for some herbivores. Hence, the copious abundance of plant biomass,typical for terrestrial ecosystems, depends on the collective regulatory action of predators on the herbivore guild. According to the counterarguments of Polis and Strong, the defensive traits of terrestrial plants attenuate terrestrial trophic cascades to species-specific trickles,so elimination of predators might lead to increased abundance of inedible plants but will not influence community-level plant biomass.

    Question: Does the elimination of predators from a low arctic scrubland, with high-quality forage plants and poorly edible evergreen ericoids, lead to a reduction of community-level plant biomass or to an increased abundance of well-defended evergreen ericoids?

    Methods: In 1991, we introduced grey-sided voles (Myodes rufocanus) to islands, initially harbouring dense scrubland vegetation, and established permanent plots there. In 2000, we transplanted vegetation blocks from a large three-trophic-level island with voles and predators,to two-trophic-level islands with introduced voles but without resident predators, and also to vole-free one-trophic-level islands, and back to the three-trophic-level island. Vole densities were monitored by semi-annual live trapping. Vegetation was monitored by the point-frequency method.

    Results: In the absence of predators, vole densities increased 3.7-fold and the communitylevel plant biomass was decimated. The least palatable plant group, evergreen ericoids,suffered especially heavily, whereas palatable herbaceous plants increased in abundance. However, all three functional plant groups responded positively to the elimination of grey-sided voles.

    Conclusions: Our results corroborate the Green World Hypothesis, indicating that in the absence of predators, plant defences do not prevent runaway consumption of the vegetation.

  • 290.
    Dahlgren, Jonas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Oksanen, Lauri
    Department of Biology, Section of Ecology, University of Turku, Turku, Finland.
    Olofsson, Johan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Oksanen, Tarja
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Plant defense at no cost?: The recovery of tundra scrubland following heavy grazing by grey-sided voles (Myodes rufocanus)2009In: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 11, p. 1205-1216Article in journal (Refereed)
    Abstract [en]

    Background: Evergreen ericaceous dwarf shrubs form a dominating component of low arctic and low alpine vegetation. They typically produce high contents of secondary chemicals such as phenolics. The primary function of these chemicals may be to defend the shrubs by making them less palatable to herbivores. Question: Does the production of secondary chemicals carry a fitness cost in terms of low growth rate and, therefore, low capacity to recover from past herbivory?

    Methods: In 2000, we constructed vole-proof exclosures on low arctic islands where vegetation had, since 1991, been heavily impacted by grey-sided voles. In 2000 and 2003,we surveyed the vegetation of the exclosures, of unfenced plots on the same islands, and of control plots on a vole-free island. We used the point-frequency method for vegetation surveys.

    Results: In the exclosures, the biomasses of most plant species increased, by and large, at the same pace. The two woody species, which increased most rapidly, were the maximally palatable bilberry (Vaccinium myrtillus) and the phenolics-laden, maximally unpalatable northern crowberry (Empetrum nigrum ssp. hermaprhoditum). The recovery rates of these species were similar.

    Conclusions: The high concentrations of phenolics typical for evergreen arctic dwarf shrubs do not carry any obvious cost in the form of reduced capacity for compensatory growth. The principle of trade-offs does not help to explain the variation in plant palatability.

  • 291.
    Dahlgren, Kristin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Olsen, Bernt Rydland
    Troedsson, Christofer
    Båmstedt, Ulf
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Seasonal variation in wax ester concentration and gut content in a Baltic Sea copepod [Limnocalanus macrurus (Sars 1863)]2012In: Journal of Plankton Research, ISSN 0142-7873, E-ISSN 1464-3774, Vol. 34, no 4, p. 286-297Article in journal (Refereed)
    Abstract [en]

    Limnocalanus macrurus from Bothnian Bay in the northern part of the Baltic Sea was studied during the ice-free period (AprilDecember) in order to understand its life history and feeding biology. Our data on the population dynamics indicated that reproduction occurred during the ice-covered period, during which lipid storage was reduced to a minimum. From spring to late summer, the lipid reserve increased by a factor of 3, while the gonads of adult females were immature during this period, continuing to December as indicated by the small size of the eggs. Average stomach fullness was always ca. 50 indicating continuous feeding activity. A newly developed denaturing high-performance liquid chromatography method was used to analyse the gut contents over the study period. More than 30 taxa (at different taxonomic levels) could be identified. However, phytoplankton was only represented by one taxon (Diatomophycea), and was restricted to July. Thus, adult L. macrurus seems to have a strongly carnivorous feeding preference in the northern Baltic Sea.

  • 292.
    Dahlqvist, Erica
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Undersökning av parametrar som kan öka mobiliteten av arsenik i grundvatten efter jordtvätt i Gudarp.2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    After soil washing in the former wood preservation industry, the concentration of As (arsenic) have increased in the groundwater. The purpose of this study was to investigate different parameters that could increase the mobility of As in the groundwater. The impact the soil wash has on the soil and it is effect on mobility will also be consider. This study will also show how As, Cu and Cr changes over time, however, the focus will be on As when the soil washing have been controlled by the As concentration. Soil and groundwater samples have been collected. Through filtration Fe (iron), Al (aluminium) and TOC (Total organic carbon) together with As have been analysed to determine a possible relation. Redox potential and As specification have also been analysed. As occur probably dissolved in the groundwater or together with DOC (Dissolved organic carbon). No link between colloids and complexes with Fe and Al together with As was found through filtration. Redox potential has no impact since the water was well oxygenated and As occurred as As(V). As and Cu follow the same time trend, while different for Cr. It is clear that the concentration of As increased in the groundwater after soil washing and that soil excavating have not the same problem with increased levels. The ground structure is changed and the clay mineral with adsorption surface is removed with soil washing. This could explain the increase of As in the groundwater. 

  • 293.
    Danielsson, Conny
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Trace analysis of dioxins and dioxin-like PCBs using comprehensive two-dimensional gas chromatography with electron capture detection2006Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), two groups of struc-turally related chlorinated aromatic hydrocarbons, generally referred to as “dioxins” are of great concern due to their extreme toxicity and presence in all compartments of the environment. Since they occur at very low levels, their analysis is complex and challenging, and there is a need for cost-efficient, reliable and rapid analytical alternatives to the expensive methods in-volving use of gas chromatography high-resolution mass spectrometry (GC-HRMS). It is im-portant to routinely monitor food and feed items to detect contaminations at an early stage. For the regulation of dioxins and dioxin-like PCBs in food and feed according to current legis-lation, large numbers of samples have to be analysed. Furthermore, soils at many industrial sites are also contaminated with dioxins and need remediation. In order to optimize the cost-efficiency of reclamation activities it is important to acquire information about the levels and distribution of dioxins in the contaminated areas.

    The aim of the studies underlying this thesis was to investigate the potential of comprehen-sive two-dimensional gas chromatography with a micro-electron capture detector (GC × GC-µECD) as a cost-effective method for analysing dioxins and dioxin-like PCBs in food, feed, fly ash and contaminated soils. Quantification studies of dioxins and dioxin-like PCBs were con-ducted and results were compared with GC-HRMS reference data. Generally, there was good agreement between both the congener-specific results and data expressed as total toxic equiva-lents (TEQs). The developed GC × GC-µECD method meets the European Community (EC) requirements for screening methods for control of dioxins and dioxin-like PCBs in food and feed. The presented results also indicate that GC × GC-µECD has potential to be used as a routine method for the congener-specific analysis of 2,3,7,8-PCDD/Fs and dioxin-like PCBs in matrices such as food and feed, fly ash and soil.

    However, to fully exploit the potential of the GC × GC-µECD technique, it should be combined with a fast and cost-efficient sample preparation procedure. Therefore, a number of certified reference materials (CRMs) were extracted using a new shape-selective pressurized liquid extraction technique with integrated carbon fractionation (PLE-C), and the purified extracts were analysed for PCDD/Fs using GC × GC-µECD. The results compared well with the certified values of a fly ash and a sandy soil CRM, but they were much too high for a com-plex clay soil CRM. It was concluded that this combination of techniques was very promising for screening ash and highly permeable soils.

    Further assessments and method revisions are still required before GC × GC-µECD can be used on a routine basis, and available software packages need to be refined in order to accelerate the data-handling procedures, which currently restrict the sample throughput.

  • 294. Datry, T.
    et al.
    Foulquier, A.
    Corti, R.
    von Schiller, D.
    Tockner, K.
    Mendoza-Lera, C.
    Clement, J. C.
    Gessner, M. O.
    Moleon, M.
    Stubbington, R.
    Gucker, B.
    Albarino, R.
    Allen, D. C.
    Altermatt, F.
    Arce, M. I.
    Arnon, S.
    Banas, D.
    Banegas-Medina, A.
    Beller, E.
    Blanchette, M. L.
    Blanco-Libreros, J. F.
    Blessing, J. J.
    Boechat, I. G.
    Boersma, K. S.
    Bogan, M. T.
    Bonada, N.
    Bond, N. R.
    Brintrup Barria, K. C.
    Bruder, A.
    Burrows, R. M.
    Cancellario, T.
    Canhoto, C.
    Carlson, S. M.
    Cauvy-Fraunie, S.
    Cid, N.
    Danger, M.
    Terra, Bianca de Freitas
    De Girolamo, A. M.
    de La Barra, Evans
    del Campo, R.
    Diaz-Villanueva, V. D.
    Dyer, F.
    Elosegi, A.
    Faye, E.
    Febria, C.
    Four, B.
    Gafny, S.
    Ghate, S. D.
    Gomez, R.
    Gómez-Gener, Lluís
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Graca, M. A. S.
    Guareschi, S.
    Hoppeler, F.
    Hwan, J. L.
    Jones, J. , I
    Kubheka, S.
    Laini, A.
    Langhans, S. D.
    Leigh, C.
    Little, C. J.
    Lorenz, S.
    Marshall, J. C.
    Martin, E.
    McIntosh, A. R.
    Meyer, E. , I
    Milisa, M.
    Mlambo, M. C.
    Morais, M.
    Moya, N.
    Negus, P. M.
    Niyogi, D. K.
    Papatheodoulou, A.
    Pardo, I
    Paril, P.
    Pauls, S. U.
    Pesic, V
    Polasek, M.
    Robinson, C. T.
    Rodriguez-Lozano, P.
    Rolls, R. J.
    Sanchez-Montoya, M. M.
    Savic, A.
    Shumilova, O.
    Sridhar, K. R.
    Steward, A. L.
    Storey, R.
    Taleb, A.
    Uzan, A.
    Vander Vorste, Ross
    Waltham, N. J.
    Woelfle-Erskine, C.
    Zak, D.
    Zarfl, C.
    Zoppini, A.
    A global analysis of terrestrial plant litter dynamics in non-perennial waterways2018In: Nature Geoscience, ISSN 1752-0894, E-ISSN 1752-0908, Vol. 11, no 7, p. 497-503Article in journal (Refereed)
    Abstract [en]

    Perennial rivers and streams make a disproportionate contribution to global carbon (C) cycling. However, the contribution of intermittent rivers and ephemeral streams (IRES), which sometimes cease to flow and can dry completely, is largely ignored although they represent over half the global river network. Substantial amounts of terrestrial plant litter (TPL) accumulate in dry riverbeds and, upon rewetting, this material can undergo rapid microbial processing. We present the results of a global research collaboration that collected and analysed TPL from 212 dry riverbeds across major environmental gradients and climate zones. We assessed litter decomposability by quantifying the litter carbon-to-nitrogen ratio and oxygen (O2) consumption in standardized assays and estimated the potential short-term CO2 emissions during rewetting events. Aridity, cover of riparian vegetation, channel width and dry-phase duration explained most variability in the quantity and decomposability of plant litter in IRES. Our estimates indicate that a single pulse of CO2 emission upon litter rewetting contributes up to 10% of the daily CO2 emission from perennial rivers and stream, particularly in temperate climates. This indicates that the contributions of IRES should be included in global C-cycling assessments.

  • 295. Davidsson, A.
    et al.
    Kjerstadius, H.
    Haghighatafshar, S.
    Fick, Jerker
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Olsson, M.
    Wachtmeister, H.
    Eriksson, E.
    Jansen, J. la Cour
    Effect of anaerobic digestion at 35, 55 and 60 degrees C on pharmaceuticals and organic contaminants2014In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 69, no 6, p. 1282-1288Article in journal (Refereed)
    Abstract [en]

    The application of treated sewage sludge on farmland is a suggested method for recycling nutrients and reducing demand for commercial fertilizer. However, sludge needs to be safe from possible contaminants which can cause acute and long-term health and environmental problems. Residual pharmaceuticals and organic contaminants are mentioned as emerging threats since wastewater treatment plants are not designed to degrade these substances. The aim of this study was to screen and evaluate the presence, and reduction, of pharmaceuticals and polycyclic aromatic hydrocarbons (PAHs) during anaerobic digestion of mixed primary and waste-activated sludge at 35, 55 and 60 degrees C and during pasteurization at 70 degrees C. The study showed the difficulty of analysing pharmaceutical compounds in low concentrations in the sludge matrix. No general reduction of these compounds was seen during treatment, but for individual substances some reduction occured. The PAHs were generally not reduced during digestion or pasteurization, but for three substances (indeno[1,2,3-cd]pyreneand dibenzo[a,h] anthracene (analysed together) and benzo [g,h,i] perylene) reduction (up to 60%) during digestion was seen. Digestion at 35 and 55 degrees C resulted in about the same order of reduction of the three individual PAHs, which was higher than for digestion at 60 degrees C.

  • 296. De Frenne, P
    et al.
    Graae, Bente Jessen
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Kolb, A
    Brunet, J
    Chabrerie, O
    Cousins, S
    Decocq, G
    Diekmann, M
    Eriksson, O
    Heinken, T
    Hermy, M
    Jõgar, Ü
    Stanton, S
    Shevtsova, A
    Zindel, Renate
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Zobel, M
    Verheyen, K
    Significant effects of temperature on the reproductive output of the forest herb Anemone nemorosa L.2010In: Forest Ecology and Management, ISSN 0378-1127, E-ISSN 1872-7042, Vol. 259, no 4, p. 809-817Article in journal (Refereed)
    Abstract [en]

    Climate warming is already influencing plant migration in different parts of the world. Numerous models have been developed to forecast future plant distributions. Few studies, however, have investigated the potential effect of warming on the reproductive output of plants. Understorey forest herbs in particular, have received little attention in the debate on climate change impacts.

    This study focuses on the effect of temperature on sexual reproductive output (number of seeds, seed mass, germination percentage and seedling mass) of Anemone nemorosa L., a model species for slow colonizing herbaceous forest plants. We sampled seeds of A. nemorosa in populations along a 2400 km latitudinal gradient from northern France to northern Sweden during three growing seasons (2005, 2006 and 2008). This study design allowed us to isolate the effects of accumulated temperature (Growing Degree Hours; GDH) from latitude and the local abiotic and biotic environment. Germination and seed sowing trials were performed in incubators, a greenhouse and under field conditions in a forest. Finally, we disentangled correlations between the different reproductive traits of A. nemorosa along the latitudinal gradient.

    We found a clear positive relationship between accumulated temperature and seed and seedling traits: reproductive output of A. nemorosa improved with increasing GDH along the latitudinal gradient. Seed mass and seedling mass, for instance, increased by 9.7% and 10.4%, respectively, for every 1000 °C h increase in GDH. We also derived strong correlations between several seed and seedling traits both under field conditions and in incubators. Our results indicate that seed mass, incubator-based germination percentage (Germ%Inc) and the output of germinable seeds (product of number of seeds and Germ%Inc divided by 100) from plants grown along a latitudinal gradient (i.e. at different temperature regimes) provide valuable proxies to parameterize key population processes in models.

    We conclude that (1) climate warming may have a pronounced positive impact on sexual reproduction of A. nemorosa and (2) climate models forecasting plant distributions would benefit from including the temperature sensitivity of key seed traits and population processes.

  • 297. De Frenne, P
    et al.
    Kolb, A
    Verheyen, K
    Brunet, J
    Chabrerie, O
    Decocq, G
    Diekmann, M
    Eriksson, O
    Heinken, T
    Hermy, M
    Jõgar, Ü
    Stanton, S
    Zindel, Renate
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Zobel, M
    Graae, BJ
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Unraveling the effects of temperature, latitude and local environment on the reproduction of six forest herbs.2009In: Global Ecology and Biogeography, ISSN 1466-822X, E-ISSN 1466-8238, Vol. 18, no 6, p. 641-651Article in journal (Refereed)
    Abstract [en]

    Aim To investigate the effect of temperature, latitude and local environment on the reproductive traits of widespread perennial forest herbs to better understand the potential impacts of rising temperatures on their population dynamics and colonization capacities.

    Location Six regions along a latitudinal gradient from France to Sweden.

    Methods Within each region, we collected data from three to five populations of up to six species. For each species, several variables were recorded in each region (temperature, latitude) and population (local abiotic and biotic environmental variables), and seed production and germination were estimated. Resource investment in reproduction (RIR) was quantified as seed number × seed mass, while germinable seed output (GSO) was expressed as seed number × germination percentage. We performed linear regression and mixed effect models to investigate the effects of temperature (growing degree hours), latitude and local abiotic and biotic environment on RIR and GSO.

    Results Temperature and latitude explained most of the variation in RIR and GSO for early flowering species with a northerly distribution range edge (Anemone nemorosa, Paris quadrifolia and Oxalis acetosella). Reproduction of the more southerly distributed species (Brachypodium sylvaticum, Circaea lutetiana and Primula elatior), in contrast, was independent of temperature/latitude. In the late summer species, B. sylvaticum and C. lutetiana, variation in RIR and GSO was best explained by local environmental variables, while none of the investigated variables appeared to be related to reproduction in P. elatior.

    Main conclusions We showed that reproduction of only two early flowering, northerly distributed species was related to temperature. This suggests that the potential reproductive response of forest herbs to climate warming partly depends on their phenology and distribution, but also that the response is to some extent species dependent. These findings should be taken into account when predictions about future shifts in distribution range are made.

  • 298. De Frenne, Pieter
    et al.
    Graae, Bente J
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Kolb, Annette
    Shevtsova, Anna
    Baeten, Lander
    Brunet, Jörg
    Chabrerie, Olivier
    Cousins, Sara A O
    Decocq, Guillaume
    Dhondt, Rob
    Diekmann, Martin
    Gruwez, Robert
    Heinken, Thilo
    Hermy, Martin
    Öster, Mathias
    Saguez, Robert
    Stanton, Sharon
    Tack, Wesley
    Vanhellemont, Margot
    Verheyen, Kris
    An intraspecific application of the leaf-height-seed ecology strategy scheme to forest herbs along a latitudinal gradient2011In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 34, no 1, p. 132-140Article in journal (Refereed)
    Abstract [en]

    We measured LHS traits in 41 Anemone nemorosa and 44 Milium effusum populations along a 1900-2300 km latitudinal gradient from N France to N Sweden. We then applied multilevel models to identify the effects of regional (temperature, latitude) and local (soil fertility and acidity, overstorey canopy cover) environmental factors on LHS traits. Both species displayed a significant 4% increase in plant height with every degree northward shift (almost a two-fold plant height difference between the southernmost and northernmost populations). Neither seed mass nor SLA showed a significant latitudinal cline. Temperature had a large effect on the three LHS traits of Anemone. Latitude, canopy cover and soil nutrients were related to the SLA and plant height of Milium. None of the investigated variables appeared to be related to the seed mass of Milium. The variation in LHS traits indicates that the ecological strategy determined by the position of each population in this three-factor triangle is not constant along the latitudinal gradient. The significant increase in plant height suggests greater competitive abilities for both species in the northernmost populations. We also found that the studied environmental factors affected the LHS traits of the two species on various scales: spring-flowering Anemone was affected more by temperature, whereas early-summer flowering Milium was affected more by local and other latitude-related factors. Finally, previously reported cross-species correlations between LHS traits and latitude were generally unsupported by our within-species approach.

  • 299. de Jong, Rixt
    et al.
    Blaauw, Maarten
    Chambers, Frank M.
    Christensen, Torben R.
    de Vleeschouwer, Francois
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Finsinger, Walter
    Fronzek, Stefan
    Johansson, Margareta
    Kokfelt, Ulla
    Lamentowicz, Mariusz
    Le Roux, Gael
    Mauquoy, Dmitri
    Mitchell, Edward A. D.
    Nichols, Jonathan E.
    Samaritani, Emanuela
    van Geel, Bas
    Climate and Peatlands2010In: Changing Climates, Earth Systems and Society, Dordrecht: Springer Netherlands, 2010, p. 85-121Chapter in book (Other academic)
    Abstract [en]

    Peatlands are an important natural archive for past climatic changes, primarily due to their sensitivity to changes in the water balance and the dating possibilities of peat sediments. In addition, peatlands are an important sink as well as potential source of greenhouse gases. The first part of this chapter discusses a range of well-established and novel proxies studied in peat cores (peat humification, macrofossils, testate amoebae, stomatal records from subfossil leaves, organic biomarkers and stable isotope ratios, aeolian sediment influx and geochemistry) that are used for climatic and environmental reconstructions, as well as recent developments in the dating of these sediments. The second part focuses on the role that peatland ecosystems may play as a source or sink of greenhouse gases. Emphasis is placed on the past and future development of peatlands in the discontinuous permafrost areas of northern Scandinavia, and the role of regenerating mined peatlands in north-western Europe as a carbon sink or source.

  • 300. de Jong, Rixt
    et al.
    Kamenik, Christian
    Westover, Karlyn
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Grosjean, Martin
    A chrysophyte stomatocyst-based reconstruction of cold-season air temperature from Alpine Lake Silvaplana (AD 1500-2003); methods and concepts for quantitative inferences2013In: Journal of Paleolimnology, ISSN 0921-2728, E-ISSN 1573-0417, Vol. 50, no 4, p. 519-533Article in journal (Refereed)
    Abstract [en]

    Relatively little is known about past cold-season temperature variability in high-Alpine regions because of a lack of natural cold-season temperature proxies as well as under-representation of high-altitude sites in meteorological, early-instrumental and documentary data sources. Recent studies have shown that chrysophyte stomatocysts, or simply cysts (sub-fossil algal remains of Chrysophyceae and Synurophyceae), are among the very few natural proxies that can be used to reconstruct cold-season temperatures. This study presents a quantitative, high-resolution (5-year), cold-season (Oct-May) temperature reconstruction based on sub-fossil chrysophyte stomatocysts in the annually laminated (varved) sediments of high-Alpine Lake Silvaplana, SE Switzerland (1,789 m a.s.l.), since AD 1500. We first explore the method used to translate an ecologically meaningful variable based on a biological proxy into a simple climate variable. A transfer function was applied to reconstruct the 'date of spring mixing' from cyst assemblages. Next, statistical regression models were tested to convert the reconstructed 'dates of spring mixing' into cold-season surface air temperatures with associated errors. The strengths and weaknesses of this approach are thoroughly tested. One much-debated, basic assumption for reconstructions ('stationarity'), which states that only the environmental variable of interest has influenced cyst assemblages and the influence of confounding variables is negligible over time, is addressed in detail. Our inferences show that past cold-season air-temperature fluctuations were substantial and larger than those of other temperature reconstructions for Europe and the Alpine region. Interestingly, in this study, recent cold-season temperatures only just exceed those of previous, multi-decadal warm phases since AD 1500. These findings highlight the importance of local studies to assess natural climate variability at high altitudes.

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