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Laudon, Hjalmar
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Publications (10 of 45) Show all publications
Berggren, M., Laudon, H. & Jansson, M. (2010). Bacterial utilization of imported organic material in three small nested humic lakes. In: Jones J, Faaborg J (Ed.), INTERNATIONAL ASSOCIATION OF THEORETICAL AND APPLIED LIMNOLOGY, VOL 30, PT 9: . Paper presented at 30th Congress of the International-Association-of-Theoretical-and-Applied-Limnology, Montreal, CANADA, AUG 12-18, 2007 (pp. 1393-1396). Stuttgart: E SCHWEIZERBART'SCHE VERLAGSBUCHHANDLUNG, 30(9)
Open this publication in new window or tab >>Bacterial utilization of imported organic material in three small nested humic lakes
2010 (English)In: INTERNATIONAL ASSOCIATION OF THEORETICAL AND APPLIED LIMNOLOGY, VOL 30, PT 9 / [ed] Jones J, Faaborg J, Stuttgart: E SCHWEIZERBART'SCHE VERLAGSBUCHHANDLUNG , 2010, Vol. 30, no 9, p. 1393-1396Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Stuttgart: E SCHWEIZERBART'SCHE VERLAGSBUCHHANDLUNG, 2010
Series
International Association of Theoretical and Applied Limnology Proceedings, ISSN 0368-0770 ; 30
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-30404 (URN)000312418900018 ()978-3-510-54080-8 (ISBN)
Conference
30th Congress of the International-Association-of-Theoretical-and-Applied-Limnology, Montreal, CANADA, AUG 12-18, 2007
Note

Part 9

Available from: 2009-12-21 Created: 2009-12-21 Last updated: 2018-06-08Bibliographically approved
Berggren, M., Laudon, H., Haei, M., Ström, L. & Jansson, M. (2010). Efficient aquatic bacterial metabolism of dissolved low-molecular-weight compounds from terrestrial sources. The ISME Journal, 4(3), 408-416
Open this publication in new window or tab >>Efficient aquatic bacterial metabolism of dissolved low-molecular-weight compounds from terrestrial sources
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2010 (English)In: The ISME Journal, ISSN 1751-7362, Vol. 4, no 3, p. 408-416Article in journal (Refereed) Published
Abstract [en]

Carboxylic acids (CAs), amino acids (AAs) and carbohydrates (CHs) in dissolved free forms can be readily assimilated by aquatic bacteria and metabolized at high growth efficiencies. Previous studies have shown that these low-molecular-weight (LMW) substrates are released by phytoplankton but also that unidentified LMW compounds of terrestrial origin is a subsidy for bacterial metabolism in unproductive freshwater systems. We tested the hypothesis that different terrestrially derived CA, AA and CH compounds can offer substantial support for aquatic bacterial metabolism in fresh waters that are dominated by allochthonous dissolved organic matter (DOM). Drainage water from three catchments of different characters in the Krycklan experimental area in Northern Sweden were studied at the rising and falling limb of the spring flood, using a 2-week bioassay approach. A variety of CA, AA and CH compounds were significantly assimilated by bacteria, meeting 15–100% of the bacterial carbon demand and explaining most of the observed variation in bacterial growth efficiency (BGE; R2=0.66). Of the 29 chemical species that was detected, acetate was the most important, representing 45% of the total bacterial consumption of all LMW compounds. We suggest that LMW organic compounds in boreal spring flood drainage could potentially support all in situ bacterial production in receiving lake waters during periods of weeks to months after the spring flood.

Place, publisher, year, edition, pages
London: Nature Publishing Group, 2010
Keywords
freshwater, growth efficiency, heterotrophic bacteria, low-molecular-weight DOM
National Category
Ecology
Research subject
Physical Geography
Identifiers
urn:nbn:se:umu:diva-30050 (URN)10.1038/ismej.2009.120 (DOI)000274800100010 ()
Available from: 2009-12-01 Created: 2009-12-01 Last updated: 2018-06-08Bibliographically approved
Berggren, M., Hjalmar, L. & Jansson, M. (2009). Aging of allochthonous organic carbon regulates bacterial production in unproductive boreal lakes. Limnology and Oceanography, 54(4), 1333-1342
Open this publication in new window or tab >>Aging of allochthonous organic carbon regulates bacterial production in unproductive boreal lakes
2009 (English)In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 54, no 4, p. 1333-1342Article in journal (Refereed) Published
Abstract [en]

We calculated average aquatic dissolved organic carbon (DOC) age (the time span from soil discharge to observation) in water from the inlets and outlets of two unproductive Swedish lakes at different times during an annual cycle. Bacterial production (BP) and bacterial growth efficiency (BGE) determined during 7-d bioassays decreased with increasing average aquatic DOC age. Parallel to the declines in BP and BGE there was a rise in specific ultraviolet absorbance at the wavelength of 254 nm (SUVA254), which indicates that decreasing BP and BGE were connected to a shift to a more aromatic and recalcitrant DOC pool. The relationships between bacterial metabolism and DOC age were stronger after a Q10 correction of the DOC age, showing that temperature affected rates of DOC quality changes over time and should be taken into account when relating lake bacterial growth to substrate aging in natural environments. We propose that hydrological variability in combination with lake size (water renewal time) have a large influence on pelagic BP in lakes with high input of terrigenous DOC.

Identifiers
urn:nbn:se:umu:diva-23250 (URN)
Available from: 2009-06-08 Created: 2009-06-08 Last updated: 2018-06-08
Tetzlaff , D., Seibert , J., McGuire , K., Laudon , H., Burn , D., Dunn , S. & Soulsby , C. (2009). How does landscape structure influence catchment transit time across different geomorphic provinces?. Hydrological Processes, 23(6), 945-953
Open this publication in new window or tab >>How does landscape structure influence catchment transit time across different geomorphic provinces?
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2009 (English)In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 23, no 6, p. 945-953Article in journal (Refereed) Published
Abstract [en]

Despite an increasing number of empirical investigations of catchment transit times (TTs), virtually all are based on individual catchments and there are few attempts to synthesize understanding across different geographical regions. Uniquely, this paper examines data from 55 catchments in five geomorphic provinces in northern temperate regions (Scotland, United States of America and Sweden). The objective is to understand how the role of catchment topography as a control on the TTs differs in contrasting geographical settings. Catchment inverse transit time proxies (ITTPs) were inferred by a simple metric of isotopic tracer damping, using the ratio of standard deviation of delta O-18 in streamwater to the standard deviation of delta O-18 in precipitation. Quantitative landscape analysis was undertaken to characterize the catchments according to hydrologically relevant topographic indices: that could be readily determined from a digital terrain model (DTM). The nature of topographic controls on transit times varied markedly in different geomorphic regions. In steeper montane regions. there are stronger gravitational influences on hydraulic gradients and TTs tend to he lower in the steepest catchments. In provinces where terrain is more subdued, direct topographic control weakened; in particular, where flatter areas with less permeable soils give rise to overland How and lower The steeper slopes within this flatter terrain appear to have a greater coverage of freely draining soils, which increase sub-surface flow, therefore increasing TTs. Quantitative landscape analysis proved a useful tool for intercatchment comparison. However, the critical influence of sub-surface permeability and connectivity may limit the transferability of predictive tools of hydrological function based on topographic parameters alone. Copyright (C) 2009 John Wiley & Sons, Ltd.

Identifiers
urn:nbn:se:umu:diva-23308 (URN)10.1002/hyp.7240 (DOI)
Available from: 2009-06-09 Created: 2009-06-09 Last updated: 2018-06-08
Berggren, M., Laudon, H. & Jansson, M. (2009). Hydrological control of organic carbon support for bacterial growth in boreal headwater streams. Microbial Ecology, 57(1), 170-178
Open this publication in new window or tab >>Hydrological control of organic carbon support for bacterial growth in boreal headwater streams
2009 (English)In: Microbial Ecology, ISSN 0095-3628, E-ISSN 1432-184X, Vol. 57, no 1, p. 170-178Article in journal (Refereed) Published
Abstract [en]

Terrestrial organic carbon is exported to freshwater systems where it serves as substrate for bacterial growth. Temporal variations in the terrigenous organic carbon support for aquatic bacteria are not well understood. In this paper, we demonstrate how the combined influence of landscape characteristics and hydrology can shape such variations. Using a 13-day bioassay approach, the production and respiration of bacteria were measured in water samples from six small Swedish streams (64° N, 19° E), draining coniferous forests, peat mires, and mixed catchments with typical boreal proportions between forest and mire coverage. Forest drainage supported higher bacterial production and higher bacterial growth efficiency than drainage from mires. The areal export of organic carbon was several times higher from mire than from forest at low runoff, while there was no difference at high flow. As a consequence, mixed streams (catchments including both mire and forest) were dominated by mire organic carbon with low support of bacterial production at low discharge situations but dominated by forest carbon supporting higher bacterial production at high flow. The stimulation of bacterial growth during high-flow episodes was a result of higher relative export of organic carbon via forest drainage rather than increased drainage of specific “high-quality” carbon pools in mire or forest soils.

Identifiers
urn:nbn:se:umu:diva-23276 (URN)10.1007/s00248-008-9423-6 (DOI)
Available from: 2009-06-09 Created: 2009-06-09 Last updated: 2018-06-08
Björkvald, L., Giesler, R., Laudon, H., Humborg, C. & Mörth, C.-M. (2009). Landscape variations in stream water SO4 and d34S-SO4 in a boreal stream network. Geochimica et Cosmochimica Acta, 73, 4648-4660
Open this publication in new window or tab >>Landscape variations in stream water SO4 and d34S-SO4 in a boreal stream network
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2009 (English)In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 73, p. 4648-4660Article in journal (Refereed) Published
Abstract [en]

Despite reduced anthropogenic deposition during the last decades, deposition sulphate may still play an important role in the biogeochemical cycles of S and many catchments may act as net sources of S that may remain for several decades. The aim of this study is to elucidate the temporal and spatial dynamics of both SO42− and δ34SSO4 in stream water from catchments with varying percentage of wetland and forest coverage and to determine their relative importance for catchment losses of S. Stream water samples were collected from 15 subcatchments ranging in size from 3 to 6780 ha, in a boreal stream network, northern Sweden. In forested catchments (<2% wetland cover) S–SO42− concentrations in stream water averaged 1.7 mg L−1 whereas in wetland dominated catchments (>30% wetland cover) the concentrations averaged 0.3 mg L−1. A significant negative relationship was observed between S–SO42− and percentage wetland coverage (r2 = 0.77, p < 0.001) and the annual export of stream water SO42− and wetland coverage (r2 = 0.76, p < 0.001). The percentage forest coverage was on the other hand positively related to stream water SO42− concentrations and the annual export of stream water SO42− (r2 = 0.77 and r2 = 0.79, respectively). The annual average δ34SSO4 value in wetland dominated streams was +7.6‰ and in streams of forested catchments +6.7‰. At spring flood the δ34SSO4 values decreased in all streams by 1‰ to 5‰. The δ34SSO4 values in all streams were higher than the δ34SSO4 value of +4.7‰ in precipitation (snow). The export of S ranged from 0.5 kg S ha−1 yr−1 (wetland headwater stream) to 3.8 kg S ha−1 yr−1 (forested headwater stream). With an average S deposition in open field of 1.3 kg S ha−1 yr−1 (2002–2006) the mass balance results in a net export of S from all catchments, except in catchments with >30% wetland. The high temporal and spatial resolution of this study demonstrates that the reducing environments of wetlands play a key role for the biogeochemistry of S in boreal landscapes and are net sinks of S. Forested areas, on the other hand were net sources of S.

Identifiers
urn:nbn:se:umu:diva-25843 (URN)10.1016/j.gca.2009.05.052 (DOI)
Available from: 2009-09-07 Created: 2009-09-07 Last updated: 2018-06-08
Giesler , R., Björkvald , L., Laudon , H. & Mörth , C. (2009). Spatial and Seasonal Variations in Stream Water delta S-34-Dissolved Organic Matter in Northern Sweden. Environmental Science and Technology, 43(2), 447-452
Open this publication in new window or tab >>Spatial and Seasonal Variations in Stream Water delta S-34-Dissolved Organic Matter in Northern Sweden
2009 (English)In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 43, no 2, p. 447-452Article in journal (Refereed) Published
Abstract [en]

The discharge of terrestrial dissolved organic matter (DOM) by streams is an important cross-system linkage that strongly influences downstream aquatic ecosystems. Isotopic tracers are important tools that can help to unravel the source of DOM from different terrestrial compartments in the landscape. Here we demonstrate the spatial and seasonal variation of delta S-34 of DOM in 70 boreal streams to test if the tracer could provide new insights into the origin of DOM. We found large spatial and seasonal variations in stream water delta S-34-DOM values ranging from -5.2 parts per thousand to + 9.6 parts per thousand with an average of +4.0 +/- 0.6 (N=62; average and 95% confidence interval). Large seasonal variations were found in stream water delta S-34-DOM values: for example, a shift of more than 10 parts per thousand during the spring snowmelt in a wetland-dominated stream. Spatial differences were also observed during the winter base flow with higher delta S-34-DOM values in the fourth-order Krycklan stream at the outlet of the 68 km(2) compared to the small (<1 km(2)) headwater streams. Our data clearly show that the delta S-34-DOM values have the potential to be used as a tracer to identify and generate new insights about terrestrial DOM sources in the boreal landscape.

Identifiers
urn:nbn:se:umu:diva-23297 (URN)10.1021/es8017946 (DOI)
Available from: 2009-06-09 Created: 2009-06-09 Last updated: 2018-06-08
Bishop, K., Buffam, I., Erlandsson, M., Fölster, J., Laudon, H., Seibert, J. & Temnerud, J. (2008). Aqua Incognita: the unknown headwaters. Hydological Processes, 22, 1239–1242
Open this publication in new window or tab >>Aqua Incognita: the unknown headwaters
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2008 (English)In: Hydological Processes, Vol. 22, p. 1239–1242-Article in journal (Refereed) Published
Abstract [en]

Running water comprises just over one millionth of the world’s water. The importance of those streams and rivers as a resource for human welfare and biodiversity, however, is far out of proportion to that minuscule fraction. This explains why protecting running waters (the flow regimes, water quality and biota) is such a vital concern for society. Yet for all the focus and concern, how much do we actually know about these running waters, and the lotic habitat they comprise?

Identifiers
urn:nbn:se:umu:diva-11445 (URN)doi:10.1002/hyp.7049 (DOI)
Available from: 2009-01-08 Created: 2009-01-08 Last updated: 2018-06-09Bibliographically approved
Soulsby, C., Neal, C., Laudon, H., Burns, D., Merot, P., Bonell, M., . . . Tetzlaff, D. (2008). Catchment data for process conceptualization: simply not enough?. Hydological Processes, 22(12), 2057-2061
Open this publication in new window or tab >>Catchment data for process conceptualization: simply not enough?
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2008 (English)In: Hydological Processes, Vol. 22, no 12, p. 2057-2061Article in journal (Refereed) Published
Identifiers
urn:nbn:se:umu:diva-11431 (URN)doi:10.1002/hyp.7068 (DOI)
Available from: 2009-01-08 Created: 2009-01-08 Last updated: 2018-06-09Bibliographically approved
Köhler, S., Buffam, I., Laudon, H. & Bishop, K. (2008). Climate's control of intra-annual and interannual variability of total organic carbon concentration and flux in two contrasting boreal landscape elements. Journal of Geophysical Research - Biogeosciences, 113(G3), Article ID G03012.
Open this publication in new window or tab >>Climate's control of intra-annual and interannual variability of total organic carbon concentration and flux in two contrasting boreal landscape elements
2008 (English)In: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 113, no G3, article id G03012Article in journal (Refereed) Published
Abstract [en]

[1] Large spatial and temporal variations in stream total organic carbon (TOC) concentration and export occurred during an 11-year observation period (1993-2003) in a boreal headwater catchment. TOC flux and concentration patterns from mire- and forest-dominated subcatchments differed ( mean annual flux 8.2 g m(-2)a(-1) versus 5.8 g m(-2) a(-1)). Temporal variations in stream TOC concentrations in both landscape types were primarily driven by variations in streamflow, with the mire stream generally diluting by half with increased runoff during spring flood and TOC from the forested landscape increasing during runoff peaks irrespective of season. Average TOC concentration in the mire stream in the snow-free season increased with increased seasonal precipitation from around 20 to 40 mg L-1 but then dropped to around 35 mg L-1 during very wet years. Average snow-free season TOC concentration at the forested site remained stable when summer precipitation was below average but then increased from 10 to around 25 mg L-1 during exceptionally wet years. For both the forested subcatchment and the whole catchment, TOC concentrations increased during the warm summer months during wet years, but no such increase occurred during dry years. Interannual variations in TOC flux were primarily driven by variations during the snow-free period. Wet years decreased the relative TOC export from the mire and favored the relative export of TOC from areas dominated by forest, an observation that also held true on a larger scale when similar landscape types were considered. Predicted climate change in rainfall and temperature patterns will affect the amount and character of TOC exported downstream from boreal landscapes with a mix of forest and mire.

Place, publisher, year, edition, pages
American Geophysical Union (AGU), 2008
National Category
Environmental Sciences related to Agriculture and Land-use
Identifiers
urn:nbn:se:umu:diva-11420 (URN)10.1029/2007JG000629 (DOI)000258153100001 ()
Available from: 2009-01-08 Created: 2009-01-08 Last updated: 2020-02-28Bibliographically approved
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