umu.sePublikationer
Ändra sökning
Avgränsa sökresultatet
123 1 - 50 av 120
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Adediran, Gbotemi A.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Liem-Nguyen, Van
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Song, Yu
    Schaefer, Jeffra K.
    Slcyllberg, Ulf
    Björn, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Microbial Biosynthesis of Thiol Compounds: Implications for Speciation, Cellular Uptake, and Methylation of Hg(II)2019Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 53, nr 14, s. 8187-8196Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cellular uptake of inorganic divalent mercury (Hg(II)) is a key step in microbial formation of neurotoxic methylmercury (MeHg), but the mechanisms remain largely unidentified. We show that the iron reducing bacterium Geobacter sulfurreducens produces and exports appreciable amounts of low molecular mass thiol (LMM-RSH) compounds reaching concentrations of about 100 nM in the assay medium. These compounds largely control the chemical speciation and bioavailability of Hg(II) by the formation of Hg(LMM-RS)<INF><INF><INF>2</INF></INF> </INF>complexes (primarily with cysteine) in assays without added thiols. By characterizing these effects, we show that the thermodynamic stability of Hg(II)-complexes is a principal controlling factor for Hg(II) methylation by this bacterium such that less stable complexes with mixed ligation involving LMM-RSH, OH-, and Cl- are methylated at higher rates than the more stable Hg(LMM-RS)<INF>2</INF> complexes. The Hg(II) methylation rate across different Hg(LMM-RS)<INF>2</INF> compounds is also influenced by the chemical structure of the complexes. In contrast to the current perception of microbial uptake of Hg, our results adhere to generalized theories for metal biouptake based on metal complexation with cell surface ligands and refine the mechanistic understanding of Hg(II) availability for microbial methylation.

  • 2. Aeppli, Christoph
    et al.
    Tysklind, Mats
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Holmstrand, Henry
    Gustafsson, Örjan
    Use of Cl and C Isotopic Fractionation to Identify Degradation and Sources of Polychlorinated Phenols: Mechanistic Study and Field Application2013Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 47, nr 2, s. 790-797Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The widespread use of chlorinated phenols (CPs) as a wood preservative has led to numerous contaminated sawmill sites. However, it remains challenging to assess the extent of in situ degradation of CPs. We evaluated the use of compound-specific chlorine and carbon isotope analysis (Cl- and C-CSIA) to assess CP biotransformation. In a laboratory system, we measured isotopic fractionation during oxidative 2,4,6-trichlorophenol dechlorination by representative soil enzymes (C. fumago chloroperoxidase, horseradish peroxidase, and laccase from T. versicolor). Using a mathematical model, the validity of the Rayleigh approach to evaluate apparent kinetic isotope effects (AKIE) was confirmed. A small but significant Cl-AKIE of 1.0022 ± 0.0006 was observed for all three enzymes, consistent with a reaction pathway via a cationic radical species. For carbon, a slight inverse isotope effect was observed (C-AKIE = 0.9945 ± 0.0019). This fractionation behavior is clearly distinguishable from reported reductive dechlorination mechanisms. Based on these results we then assessed degradation and apportioned different types of technical CP mixtures used at two former sawmill sites. To our knowledge, this is the first study that makes use of two-element CSIA to study sources and transformation of CPs in the environment.

  • 3. Ahlgren, Joakim
    et al.
    Tranvik, L
    Gogoll, A
    Waldeback, M
    Markides, K
    Rydin, E
    Sediment depth attenuation of biogenic phosphorus compounds measured by P-31 NMR2005Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 39, nr 3, s. 867-872Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Being a major cause of eutrophication and subsequent loss of water quality, the turnover of phosphorus (P) in lake sediments is in need of deeper understanding. A major part of the flux of P to eutrophic lake sediments is organically bound or of biogenic origin. This P is incorporated in a poorly described mixture of autochthonous and allochthonous sediment and forms the primary storage of P available for recycling to the water column, thus regulating lake trophic status. To identify and quantify biogenic sediment P and assess its lability, we analyzed sediment cores from Lake Erken, Sweden, using traditional P fractionation, and in parallel, NaOH extracts were analyzed using (31)p NMR. The surface sediments contain orthophosphates (ortho-P) and pyrophosphates (pyro-P), as well as phosphate mono- and diesters. The first group of compounds to disappear with increased sediment depth is pyrophosphate, followed by a steady decline of the different ester compounds. Estimated half-life times of these compound groups are about 10 yr for pyrophosphate and 2 decades for mono- and diesters. Probably, these compounds will be mineralized to ortho-P and is thus potentially available for recycling to the water column, supporting further growth of phytoplankton. In conclusion, P-31 NMR is a useful tool to asses the bioavailability of certain P compound groups, and the combination with traditional fractionation techniques makes quantification possible.

  • 4.
    Arnoldsson, Kristina
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Andersson, Patrik L
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Haglund, Peter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Formation of environmentally relevant brominated dioxins from 2,4,6,-tribromophenol via bromoperoxidase-catalyzed dimerization2012Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 46, nr 13, s. 7239-7244Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Polybrominated dibenzo-p-dioxins (PBDD) are emerging environmental pollutants with structural similarities to the highly characterized toxicants polychlorinated dibenzo-p-dioxins. The geographical and temporal variations of PBDD in biota samples from the Baltic Sea do not display features that are normally related to anthropogenic sources such as incineration, and therefore the natural formation of PBDDs has been suggested. This study of the bromoperoxidase mediated oxidative coupling of 2,4,6-tribromophenol (an abundant substance that is naturally formed in marine systems) identified the formation of ppb-level yields of 1,3,6,8-tetrabromodibenzo-p-dioxin (1,3,6,8-TeBDD) through direct condensation. Additional TeBDDs (1,3,7,9-TeBDD, 1,2,4,7-TeBDD and/or 1,2,4,8-TeBDD) and tri-BDDs (1,3,7-TrBDD and 1,3,8-TrBDD) were frequently formed, but at lower yields. The formation of these TeBDDs probably proceeds via bromine shifts or Smiles rearrangements, while the TrBDDs may result from subsequent debromination processes. Since all of the congeners formed by oxidative coupling and subsequent reactions are also found in Baltic Sea biota, the results support the theory that PBDDs are formed from natural precursors.

  • 5.
    Arnoldsson, Kristina
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Andersson, Patrik L
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Haglund, Peter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Photochemical formation of polybrominated dibenzo-p-dioxins from environmentally abundant hydroxylated polybrominated diphenyl ethers2012Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 46, nr 14, s. 7567-7574Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High levels of polybrominated dibenzo-p-dioxins (PBDDs) have been found in Baltic Sea biota, where the toxic load owing to, for example, polychlorinated dibenzo-p-dioxins and other organic pollutants is already high. The levels and geographic pattern of PBDDs suggest biogenic rather than anthropogenic origin, and both biotic and abiotic formation pathways have been proposed. Photochemical formation from hydroxylated polybrominated diphenyl ethers (OH-PBDE) is a proposed pathway. for PBDDs in marine environments. Ultraviolet radiation-initiated transformations of OH-BDEs 47, 68, 85, 90, 99, and 123, which all are abundant in the environment, were investigated. It was shown that the most abundant PBDDs in the environment (1,3,7-triBDD and 1,3,8-triBDD) can be formed from the most abundant OH-BDEs (OH-BDE 47 and OH-BDE 68) at high rates and with percentage yields. In fact, most of the PBDDs that have been identified in the Baltic Sea environment were formed with high yield from the six studied OH-PBDE, through initial cyclization and subsequent debromination reactions. The high formation yields point to this route as an important source of PBDDs in biota. However, congeners showing relatively high retention in fish, specifically 1,3,6,8- and 1,3,7,9-tetraBDD, were not formed. These are likely formed by enzymatic coupling of brominated phenols.

  • 6. Arp, Hans Peter H.
    et al.
    Lundstedt, Staffan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Josefsson, Sarah
    Cornelissen, Gerard
    Enell, Anja
    Allard, Ann-Sofie
    Kleja, Dan Berggren
    Native Oxy-PAHs, N-PACs, and PAHs in historically contaminated soils from Sweden, Belgium, and France: their soil-porewater partitioning behavior, bioaccumulation in Enchytraeus crypticus, and bioavailability2014Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 48, nr 19, s. 11187-11195Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Soil quality standards are based on partitioning and toxicity data for laboratory-spiked reference soils, instead of real world, historically contaminated soils, which would be more representative. Here 21 diverse historically contaminated soils from Sweden, Belgium, and France were obtained, and the soil-porewater partitioning along with the bioaccumulation in exposed worms (Enchytraeus crypticus) of native polycyclic aromatic compounds (PACs) were quantified. The native PACs investigated were polycyclic aromatic hydrocarbons (PAHs) and, for the first time to be included in such a study, oxygenated-PAHs (oxy-PAHs) and nitrogen containing heterocyclic PACs (N-PACs). The passive sampler polyoxymethylene (POM) was used to measure the equilibrium freely dissolved porewater concentration, C-pw, of all PACs. The obtained organic carbon normalized partitioning coefficients, K-TOC, show that sorption of these native PACs is much stronger than observed in laboratory-spiked soils (typically by factors 10 to 100), which has been reported previously for PAHs but here for the first time for oxy-PAHs and N-PACs. A recently developed K-TOC model for historically contaminated sediments predicted the 597 unique, native K-TOC values in this study within a factor 30 for 100% of the data and a factor 3 for 58% of the data, without calibration. This model assumes that TOC in pyrogenic-impacted areas sorbs similarly to coal tar, rather than octanol as typically assumed. Black carbon (BC) inclusive partitioning models exhibited substantially poorer performance. Regarding bioaccumulation, C-pw combined with liposome-water partition coefficients corresponded better with measured worm lipid concentrations, C-lipid (within a factor 10 for 85% of all PACs and soils), than C-pw combined with octanol-water partition coefficients (within a factor 10 for 76% of all PACs and soils). E. crypticus mortality and reproducibility were also quantified. No enhanced mortality was observed in the 21 historically contaminated soils despite expectations from PAH spiked reference soils. Worm reproducibility weakly correlated to C-lipid of PACs, though the contributing influence of metal concentrations and soil texture could not be taken into account. The good agreement of POM-derived C-pw with independent soil and lipid partitioning models further supports that soil risk assessments would improve by accounting for bioavailability. Strategies for including bioavailability in soil risk assessment are presented.

  • 7.
    Assefa, Anteneh Taye
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Sobek, Anna
    Sundqvist, Kristina L.
    Cato, Ingemar
    Jonsson, Per
    Tysklind, Mats
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wiberg, Karin
    Temporal Trends of PCDD/Fs in Baltic Sea Sediment Cores Covering the 20th Century2014Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 48, nr 2, s. 947-953Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The pollution trend of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the Baltic Sea region was studied based on depth profiles of PCDD/Fs in sediment cores collected from six offshore areas, eight coastal sites impacted by industrial/urban emissions, and one coastal reference site. A general trend was observed for the offshore and coastal reference sites with substantial increase in PCDD/F concentrations in the mid-late 1970s and peak levels during 1985-2002. The overall peak year for PCDD/Fs in Baltic Sea offshore areas was estimated (using spline-fit modeling) to 1994 ± 5 years, and a half-life in sediments was estimated at 29 ± 11 years. For the industrial/urban impacted coastal sites, the temporal trend was more variable with peak years occurring 1-2 decades earlier compared to offshore areas. The substantial reductions from peak levels (38 ± 11% and 81 ± 12% in offshore and coastal areas, respectively) reflect domestic and international actions taken for reduction of the release of PCDD/Fs to the environment. The modeled overall half-life and reductions of PCDD/Fs in offshore Baltic Sea sediment correspond well to both PCDD/F trends in European lakes without any known direct PCDD/F sources (half-lives 30 and 32 years), and previously modeled reduction in atmospheric deposition of PCDD/Fs to the Baltic Sea since 1990. These observations support previous findings of a common diffuse source, such as long-range air transport of atmospheric emissions, as the prime source of PCDD/Fs to the Baltic Sea region. The half-life of PCDD/Fs in Baltic Sea offshore sediments was estimated to be approximately 2 and 4-6 times longer than in semirural and urban European air, respectively. This study highlights the need for further international actions to reduce the levels of PCDD/Fs in Baltic Sea air specifically and in European air in general.

  • 8.
    Augulyte, Lijana
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Kemi.
    Bergqvist, Per-Anders
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Kemi.
    Estimation of Water Sampling Rates and Concentrations of PAHs in a Municipal Sewage Treatment Plant Using SPMDs with Performance Reference Compounds2007Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 41, nr 14, s. 5044-5049Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Semipermeable membrane devices (SPMDs) were exposed at ten sampling points, each representing a different stage in the treatment process, in a municipal sewage treatment plant. Differences in SPMD uptake kinetics of polycyclic aromatic hydrocarbons (PAHs) due to variations in conditions at the sampling sites were evaluated by using five performance reference compounds (PRCs) with log Kow values of 4.20 to 6.34. PRC release rate constants (ke,PRC values) were calculated for PRCs for which 50-98% of the initial amounts were lost during the sampling period. The ke,PRC values were high, ranging from 0.08 to 0.11 day-1 for the studied PRCs, at sampling site W1 (raw sewage), the only sampling site where significant amounts of the PRCs with log Kow values >5 were released from the SPMDs. At the other sampling sites, only PRCs with log Kow values between 4.20 and 4.50 were released in significant amounts. The release rates at these sites were lowest (0.04 day-1) at sampling site W9 (the secondary clarifier) and highest (0.18 day-1) at W8 (the active sludge aeration basin). Differences between sampling rates (Rs) obtained using published laboratory-calibrated data and PRC-corrected Rs values were visualized by principal component analysis (PCA). The water concentrations of 24 studied PAHs fell substantially during the course of the sewage treatment process. However, low molecular weight PAHs were more effectively removed than high molecular weight PAHs. Significant deviations between actual and estimated water concentrations may arise unless PRC-corrected Rs values are applied.

  • 9.
    Badea, Silviu-Laurentiu
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Vogt, Carsten
    Weber, Stefanie
    Danet, Andrei-Florin
    Richnow, Hans-Hermann
    Stable isotope fractionation of γ-Hexachlorocyclohexane (Lindane) during reductive dechlorination by two strains of sulfate-reducing bacteria2009Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 43, nr 9, s. 3155-3161Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Carbon isotope fractionation factors were determined with the dichloro elimination of γ-hexachlorocyclohexane (γ-HCH) by the sulfate-reducing bacteria Desulfococcus multivorans DSM 2059 and Desulfovibrio gigas DSM 1382. Both strains are known for cometabolic HCH dechlorination. Degradation experiments with γ-HCH in concentrations of 22−25 μM were carried out using benzoate (for D. multivorans) and lactate (for D. gigas) as electron donors, respectively. γ-HCH was dechlorinated by both bacterial strains within four weeks, and the metabolites γ-3,4,5,6-tetrachlorocyclohexene (γ-TCCH), chlorobenzene (CB), and benzene were formed. The carbon isotope fractionation of γ-HCH dechlorination was quantified by the Rayleigh model, using a bulk enrichment factor (εC) of −3.9 ± 0.6 for D. gigas and −3.4 ± 0.5 for D. multivorans, which correspond to apparent kinetic isotope effect (AKIEC) values of 1.023 ± 0.004 or 1.02 ± 0.003 for stepwise Cl−C bond cleavage. The extent and range of isotope fractionation suggest that γ-HCH dechlorination can be monitored in anoxic environments by compound-specific isotope analysis (CSIA).

  • 10.
    Bergknut, Magnus
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wiberg, Karin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Klaminder, Jonatan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Vertical and lateral redistribution of POPs in soils developed along a hydrological gradient2011Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 45, nr 24, s. 10378-10384Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Study of the dispersion of persistent organic pollutants (POPs) throughout the environment is necessitated by their toxicological properties and propensity to accumulate in biota. In this study, we use data from the analysis of three (210)Pb dated soil profiles collected along a 30-m hydrological gradient to demonstrate postdepositional mobility of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs). We found that (i) humus originating from litter exposed to surface fallout during the 1960-1970s contains the highest concentrations of PCDD/Fs and PCBs in the O-horizon of the soils; (ii) accumulation rates of PCDD/Fs and PCBs in the O-horizon (similar to 5.0 and similar to 210 mu g m(-2) yr(-1)) constituted only 9.1% and 3.5%, respectively, of the measured annual input, demonstrating that a minor fraction of the deposited material is retained within the O-horizon; (iii) POP inventories in the upper 0.5-0.9 m of the mineral soil constituted a considerable part (40-70%) of the total pool stored in the soil, implying significant vertical translocation of atmospheric derived POPs; and (iv) increasing downslope inventories of POPs suggest a lateral downward transport of POPs from uphill soils. The findings challenge the commonly accepted view that POPs fallout is effectively retained within O-horizons.

  • 11.
    Berglund, Åsa
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Klaminder, Jonatan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nyholm, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Effects of reduced lead deposition on Pied flycatcher (Ficedula hypoleuca): tracing exposure routes using stable lead Isotopes2009Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 43, nr 1, s. 208-213Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To what extent the lead burden of birds living in strongly contaminated ecosystems is responding to decreased atmospheric lead deposition is not well known. In this study, we measured lead concentrations and stable lead isotope ratios (206Pb/207Pb and 208Pb/207Pb) in liver and feces from pied flycatcher nestlings (Ficedula hypoleuca) along a 90 km pollution gradient from the Rönnskär smelter in northern Sweden. Changes in lead concentration in the birds from 1984 to 2006 were used for assessing the recovery of the environment following reduced lead emissions at the smelter. The 206Pb/207Pb and 208Pb/207Pb ratios were used to identify lead sources to the birds. Lead concentrations in liver and feces have decreased since the 1980s, typically by 9−15% (liver) and 18−40% (feces) as a result of a 98% emission reduction. This relatively weak recovery is explained by a transfer of old lead contaminants accumulated in soil to the birds via their prey, which was evident by a 206Pb/207Pb ratio in liver tissue (1.15 ± 0.01) that overlapped with the ratio in ants (1.16 ± 0.01) and organic soil horizon (1.17 ± 0.01) rather than the current atmospheric lead pollution (1.11 ± 0.01). Our findings suggest that insectivorous birds living around smelters may remain contaminated decades after ceased emissions.

  • 12.
    Bidleman, Terry F.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Letter to the Editor regarding 'Celebrating Bidleman's 1988 "Atmospheric Processes"2015Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 49, nr 5, s. 2586-2586Artikel i tidskrift (Refereegranskat)
  • 13.
    Bidleman, Terry F.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Agosta, Kathleen
    Andersson, Agneta
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Haglund, Peter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Nygren, Olle
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Ripszam, Matyas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Tysklind, Mats
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Air-water exchange of brominated anisoles in the northern baltic sea2014Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 48, nr 11, s. 6124-6132Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bromophenols produced by marine algae undergo O-methylation to form bromoanisoles (BAs), which are exchanged between water and air. BAs were determined in surface water of the northern Baltic Sea (Gulf of Bothnia, consisting of Bothnian Bay and Bothnian Sea) during 2011-2013 and on a transect of the entire Baltic in September 2013. The abundance decreased in the following order: 2,4,6-tribromoanisole (2,4,6-TBA) > 2,4-dibromoanisole (2,4-DBA) ≫ 2,6-dibromoanisole (2,6-DBA). Concentrations of 2,4-DBA and 2,4,6-TBA in September were higher in the southern than in the northern Baltic and correlated well with the higher salinity in the south. This suggests south-to-north advection and dilution with fresh riverine water enroute, and/or lower production in the north. The abundance in air over the northern Baltic also decreased in the following order: 2,4,6-TBA > 2,4-DBA. However, 2,6-DBA was estimated as a lower limit due to breakthrough from polyurethane foam traps used for sampling. Water/air fugacity ratios ranged from 3.4 to 7.6 for 2,4-DBA and from 18 to 94 for 2,4,6-TBA, indicating net volatilization. Flux estimates using the two-film model suggested that volatilization removes 980-1360 kg of total BAs from Bothnian Bay (38000 km(2)) between May and September. The release of bromine from outgassing of BAs could be up to 4-6% of bromine fluxes from previously reported volatilization of bromomethanes and bromochloromethanes.

  • 14.
    Bidleman, Terry Frank
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Centre for Atmospheric Research Experiments (CARE), Environment Canada, 6248 Eighth Line, Egbert, ON, L0L 1N0, Canada.
    Stern, Gary A.
    Tomy, Gregg T.
    Hargrave, Barry T.
    Jantunen, Liisa M.
    Macdonald, Robie W.
    Scavenging amphipods: sentinels for penetration of mercury and persistent organic chemicals into food webs of the deep arctic ocean2013Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 47, nr 11, s. 5553-5561Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Archived specimens of the scavenging amphipod Eurythenes gryllus, collected from 2075 to 4250 m below the surface on five expeditions to the western and central Arctic Ocean between 1983 and 1998, were analyzed for total mercury (∑Hg), methyl mercury (MeHg), polychlorinated biphenyls (PCBs) and other industrial or byproduct organochlorines (chlorobenzenes, pentachloroanisole, octachlorostyrene), organochlorine pesticides (OCPs), and polybrominated diphenyl ethers (PBDEs). Median ∑Hg concentrations ranged from 70 to 366 ng g(-1) wet weight (ww). MeHg concentrations (3.55 to 23.5 ng g(-1) ww) accounted for 1.7 to 20.1% (median 3.7%) of ∑Hg. ∑Hg and MeHg were positively and significantly correlated with ww (∑Hg r(2) = 0.18, p = 0.0004, n = 63; MeHg r(2) = 0.42, p = 0.0004, n = 25), but not significantly with δ(13)C nor δ(15)N. Median concentrations of total persistent organic pollutants (POPs) ranged from 9750 to 156 000 ng g(-1) lipid weight, with order of abundance: ∑TOX (chlorobornanes quantified as technical toxaphene) > ∑PCBs > ∑DDTs > ∑chlordanes > ∑mirex compounds > ∑BDEs ∼ ∑chlorobenzenes ∼ octachlorostyrene > α-hexachlorocyclohexane ∼ hexachlorobenzene ∼ pentachloroanisole. Enantioselective accumulation was found for the chiral OCPs o,p'-DDT, cis- and trans-chlordane, nonachlor MC6 and oxychlordane. Lipid-normalized POPs concentrations were elevated in amphipods with lipid percentages ≤10%, suggesting that utilization of lipids resulted in concentration of POPs in the remaining lipid pool. Multidimensional Scaling (MDS) analysis using log-transformed physiological variables and lipid-normalized organochlorine concentrations distinguished amphipods from the central vs western arctic stations. This distinction was also seen for PCB homologues, whereas profiles of other compound classes were more related to specific stations rather than central-west differences.

  • 15. Bidleman, TF
    et al.
    Jantunen, LMM
    Wiberg, Karin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Harner, T
    Brice, K
    Su, K
    Falconer, RL
    Leone, AD
    Aigner, EJ
    Parkhurst, WJ
    Soil as a source of atmospheric heptachlor epoxide1998Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 32, nr 10, s. 1546-1548Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The chiral pesticide heptachlor can undergo photolysis to yield the racemic products heptachlor-exo-epoxide (HEPX) and photoheptachlor. Heptachlor is also metabolized to nonracemic HEPX in biological systems and soils. HEPX in ambient air samples from the southern United States and Lakes Ontario and Superior was nonracemic and enriched in the (+) enantiomer. Average enantiomer ratios (ER = areas of (+)/(-) HEPX) in these locations ranged from 1.51 to 2.02, and were similar to ER values of HEPX reported for agricultural soils. Airborne heptachlor was racemic, with ERs of 0.98-1.02. These results suggest that the main source of HEPX in ambient air is not photolysis of heptachlor, hut rather metabolism of heptachlor in soils followed by volatilization of HEPX. The study exemplifies the use of chiral analysis for investigating the environmental fate of pesticides.

  • 16.
    Bindler, Richard
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Yu, Ruilian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. College of Chemical Engineering, Huaqiao University, Xiamen, Fujian 361021, P.R. China.
    Hansson, Sophia
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Classen, Neele
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Karlsson, Jon
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Mining, Metallurgy and the Historical Origin of Mercury Pollution in Lakes and Watercourses in Central Sweden2012Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 46, nr 15, s. 7984-7991Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In Central Sweden an estimated 80% of the lakes contain fish exceeding health guidelines for mercury. This area overlaps extensively with the Bergslagen ore region, where intensive mining of iron ores and massive sulfide ores occurred over the past millennium. Although only a few mines still operate today, thousands of mineral occurrences and mining sites are documented in the region. Here, we present data on long-term mercury pollution in 16 sediment records from 15 lakes, which indicate that direct release of mercury to lakes and watercourses was already significant prior to industrialization (<AD 1800). Thirteen of our lakes show increases in mercury from 3-fold-equivalent to the enrichment factor in many remote lakes today-to as much as 60-fold already during the period AD 1500-1800, with the highest values in the three lakes most closely connected to major mines. Although the timing and magnitude of the historical increases in mercury are heterogeneous among lakes, the data provide unambiguous evidence for an incidental release of mercury along with other mining metals to lakes and watercourses, which suggests that the present-day problem of elevated mercury concentrations in the Bergslagen region can trace its roots back to historical mining.

  • 17.
    Boily, Jean-François
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Gassman, Paul L
    Peretyazhko, Tetyana
    Szanyi, János
    Zachara, John M
    FTIR spectral components of schwertmannite2010Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 44, nr 4, s. 1185-1190Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fourier transform infrared (FTIR) spectral components of three dominant groups of sulfate species in synthetic schwertmannite (Fe8O8(OH)6-x(SO4)x*nH2O) are presented. These components were extracted by multivariate curve resolution analysis of spectra obtained from N2(g)-dry samples initially reacted in aqueous solutions (pH 3-9) at room temperature. Each component contains complex sets of bands that correspond to mixtures of similar species. We tentatively assign these components to sulfate ions that are hydrogen- (components I and III) and iron-bonded (component I) to schwertmannite. Another component (II) is assigned to protonated sulfate species. Heating experiments to 130 degrees C moreover confirmed this possibility for component II. The spectral components extracted from this study can be used to identify dominant sulfate species in FTIR spectra of naturally occurring schwertmannite samples.

  • 18. Cao, Lin-Ying
    et al.
    Zheng, Ziye
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Ren, Xiao-Min
    Andersson, Patrik L.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Guo, Liang-Hong
    Structure-dependent activity of polybrominated diphenyl ethers and their hydroxylated metabolites on estrogen related receptor gamma: in vitro and in silico study2018Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 52, nr 15, s. 8894-8902Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Estrogen-related receptor gamma (ERR gamma) is an orphan nuclear receptor having functional cross-talk with classical estrogen receptors. Here, we investigated whether ERR gamma is a potential target 8 of polybrominated diphenyl ethers (PBDEs) and their hydroxylated metabolites (OH-PBDEs). By using a fluorescence competitive binding method established in our laboratory, the binding potencies of 30 PBDEs/OH-PBDEs with ERR gamma were determined for the first time. All of the tested OH-PBDEs and some PBDEs bound to ERR gamma with K-d values ranging from 0.13-13.61 mu M. The OH-PBDEs showed much higher binding potency than their parent PBDEs. A quantitative structure-activity relationship (QSAR) model was developed to analyze the chemical binding potencies in relation to their structural and chemical characteristics. The QSAR model indicated that the molecular size, relative ratios of aromatic atoms, and hydrogen bond donors and acceptors were crucial factors for PBDEs/OH-PBDEs binding. By using a reporter gene assay, we found that most of the low-brominated PBDEs/OH-PBDEs exerted agonistic activity toward ERR gamma, while high-brominated PBDEs/OH-PBDEs had no effect on the basal ERR gamma activity. The docking results showed that the low-brominated PBDEs/OH-PBDEs tended to take an agonistic binding mode while the high-brominated ones tended to take an antagonistic binding mode. Overall, our results suggest ERR gamma to be a potential novel target for PBDEs/OH-PBDEs.

  • 19. De Laender, F.
    et al.
    Verschuren, D.
    Bindler, Richard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Thas, O.
    Janssen, C. R.
    Biodiversity of Freshwater Diatom Communities during 1000 Years of Metal Mining, Land Use, and Climate Change in Central Sweden2012Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 46, nr 16, s. 9097-9105Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We subjected a unique set of high-quality paleoecological data to statistical modeling to examine if the biological richness and evenness of freshwater diatom communities in the Falun area, a historical copper (Cu) mining region in central Sweden, was negatively influenced by 1000 years of metal exposure. Contrary to ecotoxicological predictions, we found no negative relation between biodiversity and the sedimentary concentrations of eight metals. Strikingly, our analysis listed metals (Co, Fe, Cu, Zn, Cd, Pb) or the fractional land cover of cultivated crops, meadow, and herbs indicating land disturbance as potentially promoting biodiversity. However, correlation between metal-and land-cover trends prevented concluding which of these two covariate types positively affected biodiversity. Because historical aqueous metal concentrations-inferred from solid-water partitioning-approached experimental toxicity thresholds for freshwater algae, positive effects of metal mining on biodiversity are unlikely. Instead, the positive relationship between biodiversity and historical land-cover change can be explained by the increasing proportion of opportunistic species when anthropogenic disturbance intensifies. Our analysis illustrates that focusing on the direct toxic effects of metals alone may yield inaccurate environmental assessments on time scales relevant for biodiversity conservation.

  • 20.
    Drott, Andreas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Björn, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Bouchet, Sylvain
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Skyllberg, Ulf
    SLU.
    Refining Thermodynamic Constants for Mercury(II)-Sulfides in Equilibrium with Metacinnabar at Sub-Micromolar Aqueous Sulfide Concentrations2013Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 47, nr 9, s. 4197-4203Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An important issue in mercury (Hg) biogeochemistry is to explore the influence of aqueous Hg(II) forms on bacterial uptake, and subsequent methyl mercury formation, under iron(III) and sulfate reducing conditions. The success of this is dependent on relevant information on the thermodynamic stability of Hg-sulfides. In the present study, we determined the solubility of a commercially available HgS(s) phase, which was shown by X-ray diffraction to be a mixture of 83% metacinnabar and 17% cinnabar. At aqueous sulfide concentrations between 0.060 and 84 µM, well below levels in previous studies, we report a solubility product (log Ksp±SE) of -36.8±0.3 (HgS(s) + H+ = Hg2+ + HS-, I=0, T=25°C, pH 6-10, n=20) for metacinnabar. This value is 0.7 log units higher than previous estimates. Complementing our data with data from Paquette and Helz (1997), we took advantage of a large data set (n=65) covering a wide range of aqueous sulfide (0.06 µM-140 mM), and pH (1-11). Based on this we report refined formation constants (±SE) for the three aqueous Hg(II)-sulfide species proposed by Schwarzenbach and Widmer (1963): Hg2+ + 2HS- = Hg(SH)20; log K = 39.1±0.1, Hg2+ + 2HS- = HgS2H- + H+; log K = 32.5±0.1, Hg2+ + 2HS- = HgS22- + 2H+; log K = 23.2±0.1. Our refined log K values differ from previous estimates by 0.2-0.6 log units. Furthermore, at the low sulfide concentrations in our study we could rule out the value of -10.0 for the reaction HgS(s) + H2O = HgOHSH(aq), as reported by Dyrssén and Wedborg (1991). By establishing a solubility product for the most environmentally relevant HgS(s) phase, metacinnabar, and extending the range of aqueous sulfide concentrations to sub-µM levels, relevant for soils, sediments and waters, this study decreases the uncertainty in stability constants for Hg-sulfides, thereby improving the basis for understanding the bioavailability and mobility of Hg(II) in the environment.

  • 21. Drott, Andreas
    et al.
    Lambertsson, Lars
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Björn, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Skyllberg, Ulf
    Do Potential Methylation Rates Reflect Accumulated Methyl Mercury in Contaminated Sediments?2008Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 42, nr 1, s. 153-158Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Relationships between the short-term mono-methyl mercury (MeHg) production, determined as the specific, potential methylation rate constant Km (day−1) after 48 h of incubation with isotope-enriched 201Hg(II) at 23 °C, and the long-term accumulation of ambient MeHg, were investigated in contaminated sediments. The sediments covered a range of environments from small freshwater lakes to large brackish water estuaries and differed with respect to source and concentration of Hg, salinity, primary productivity, quantity and quality of organic matter, and temperature climate. Significant (p < 0.001), positive relationships were observed between Km (day−1) and the concentration of MeHg normalized to total Hg (%MeHg) for surface sediments (0–10, 0–15, and in one case 0–20 cm) across all environments, and across subsets of organic and minerogenic freshwaters. This suggests that the methylation process (MeHg production) overruled demethylation and net transport processes in the surface sediments. The lack of a relationship between Km and %MeHg in two brackish water sediment depth profiles (0–100 cm) indicates that demethylation and the net effect of input−output are relatively more important at greater depths. Differences in the primary production and subsequent availability of easily degradable organic matter (serving as electron donor for methylating bacteria) was indicated to be the most important factor behind observed differences in %MeHg and Km among sites. In contrast, concentrations of sulfate were not correlated to Km, %MeHg, or absolute concentrations of MeHg. We conclude that total concentrations of Hg are of importance for the long-term accumulation of MeHg, and that %MeHg in surface sediments can be used as a proxy for the rate of methylation, across a range of sites from different environments.

  • 22. Du, Xinyu
    et al.
    Yuan, Bo
    Zhou, Yihui
    Zheng, Ziye
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wu, Yan
    Qiu, Yanling
    Zhao, Jianfu
    Yin, Ge
    Tissue-Specific Accumulation, Sexual Difference, and Maternal Transfer of Chlorinated Paraffins in Black-Spotted Frogs2019Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 53, nr 9, s. 4739-4746Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The restriction on usage of short-chain chlorinated paraffins (SCCPs) under Stockholm Convention may promote the production and application of medium chain chlorinated paraffins (MCCPs) and long chain chlorinated paraffins (LCCPs) as substitutes. This study focused on the tissue-specific exposure to SCCPs, MCCPs, and LCCPs in black-spotted frog, a prevalent amphibian species in the Yangtze River Delta, China. The total CP concentrations in frog liver, muscle, and egg samples ranged of 35-1200, 6.3-97, and 6.8-300 ng/g wet weight (ww), respectively. Livers and eggs contained primary SCCPs (on average 78%) while MCCPs (43%) together with SCCPs (41%) were dominant in muscles. A significantly negative correlation was observed between hepatosomatic index and CPs concentration in liver (p < 0.01), indicating that CP exposure may lower survival rates of frogs by suppressing the energy storage in liver. Additionally, maternal transfer, an important uptake pathway for CPs, was evaluated for the first time by calculating the ratios of CP levels in eggs to those in their paired liver tissues. The ratio of egg to liver for CP congener groups raised with the increasing of log K-ow values, indicating mother to egg transport of CPs was related to the lipophilicity of the chemicals.

  • 23.
    Duc, Nguyen Thanh
    et al.
    Department of Geological Sciences, Stockholm University, 106 91 Stockholm, Sweden.
    Silverstein, Samuel
    Department of Physics, Stockholm University, 106 91 Stockholm, Sweden.
    Lundmark, Lars
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Reyier, Henrik
    Department of Water and Environmental Studies, Linköping University, 58183 Linköping, Sweden.
    Crill, Patrick
    Department of Geological Sciences, Stockholm University, 106 91 Stockholm, Sweden.
    Bastviken, David
    Department of Water and Environmental Studies, Linköping University, 58183 Linköping, Sweden.
    Automated Flux Chamber for Investigating Gas Flux at Water-Air Interfaces2013Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 47, nr 2, s. 968-975Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aquatic ecosystems are major sources of greenhouse gases (GHG). Representative measurements of GHG fluxes from aquatic ecosystems to the atmosphere are vital for quantitative understanding of relationships between biogeochemistry and climate. Fluxes occur at high temporal variability at diet or longer scales, which are not captured by traditional short-term deployments (often in the order of 30 min) of floating flux chambers. High temporal frequency measurements are necessary but also extremely labor intensive if manual flux chamber based methods are used. Therefore, we designed an inexpensive and easily mobile automated flux chamber (AFC) for extended deployments. The AFC was designed to measure in situ accumulation of gas in the chamber and also to collect gas samples in an array of sample bottles for subsequent analysis in the laboratory, providing two independent ways of CH4 concentration measurements. We here present the AFC design and function together with data from initial laboratory tests and from a field deployment.

  • 24. Ecke, Frauke
    et al.
    Singh, Navinder J.
    Arnemo, Jon M.
    Bignert, Anders
    Helander, Björn
    Berglund, Åsa M. M.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Borg, Hans
    Bröjer, Caroline
    Holm, Karin
    Lanzone, Michael
    Miller, Tricia
    Nordström, Åke
    Räikkönen, Jannikke
    Rodushkin, Ilia
    Ågren, Erik
    Hörnfeldt, Birger
    Sublethal Lead Exposure Alters Movement Behavior in Free-Ranging Golden Eagles2017Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 51, nr 10, s. 5729-5736Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lead poisoning of animals due to ingestion of fragments from lead-based ammunition in carcasses and offal of shot wildlife is acknowledged globally and raises great concerns about potential behavioral effects leading to increased mortality risks. Lead levels in blood were correlated with progress of the moose hunting season. Based on analyses of tracking data, we found that even sublethal lead concentrations in blood (25 ppb, wet weight), can likely negatively affect movement behavior (flight height and movement rate) of free ranging scavenging Golden Eagles (Aquila chrysaetos). Lead levels in liver of recovered post-mortem analyzed eagles suggested that sublethal exposure increases the risk of mortality in eagles. Such adverse effects on animals are probably common worldwide and across species, where game hunting with lead-based ammunition is widespread. Our study highlights lead exposure as a considerably more serious threat to wildlife conservation than previously realized and suggests implementation of bans of lead ammunition for hunting.

  • 25. Enell, Anja
    et al.
    Lundstedt, Staffan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Arp, Hans Peter H.
    Josefsson, Sarah
    Cornelissen, Gerard
    Wik, Ola
    Kleja, Dan Berggren
    Combining Leaching and Passive Sampling To Measure the Mobility and Distribution between Porewater, DOC, and Colloids of Native Oxy-PAHs, N-PACs, and PAHs in Historically Contaminated Soil2016Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 50, nr 21, s. 11797-11805Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Different methods to quantify soil porewater concentrations of contaminants will provide different types of information. Passive sampling measurements give freely dissolved porewater concentrations (C-pw,C-free), while leaching tests provide information on the mobile concentration (C-pw,C-leach), including contaminants associated with dissolved organic carbon (DOC) and particles/colloids in the porewater. This study presents a novel combination of these two measurements, to study the sorption and mobility of polycyclic aromatic compounds (PACs) to DOC and particulate organic carbon (POC) in 10 historically contaminated soils. The PACs investigated were polycyclic aromatic hydrocarbons (PAHs), oxygenated-PAHs, and nitrogen containing heterocyclic PACs. Observed C-pw,C-leach was up to 5 orders of magnitude higher than C-pw,C-free; implying large biases when C-pw,C-leach is used to assess bioavailability or soil partitioning. Sorption of PACs to DOC and POC was important for the mobility of compounds with log K-OW > 4. Average DOC/water-partitioning coefficients (K-DOC) correlated well with KOW (log K-DOC = 0.89 x log K-OW +1.03 (r(2) = 0.89)). This relationship is likely more accurate for historically contaminated soils than previously published data, which suffer from artifacts caused by problems in measuring C-pw,C-free correctly or not using historically contaminated soils. POC/water-partitioning coefficients (K-POC) were orders of magnitude larger than corresponding K-DOC, suggesting sorption to mobile particles/colloids is the dominant mechanism for PAC mobility.

  • 26. Englund, Edvard
    et al.
    Aldahan, Ala
    Possnert, Göran
    Haltia-Hovi, Eeva
    Hou, Xiaolin
    Renberg, Ingemar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Saarinen, Timo
    Modeling Fallout of Anthropogenic 129I2008Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 42, nr 24, s. 9225-9230Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Despite the relatively well-recognized emission rates of the anthropogenic 1291, there is little knowledge about the temporal fallout patterns and magnitude of fluxes since the start of the atomic era at the early 1940s. We here present measurements of annual 1291 concentrations in sediment archives from Sweden and Finland covering the period 1942-2006. The results revealed impression of 1291 emissions from the nuclear reprocessing facility at Sellafield and La Hague and a clear Chernobyl fallout enhancement during 1986. In order to estimate relative contributions from the different sources, a numerical model approach was used taking into account the emission rates/estimated fallout, transport pathways, and the sediment system. The model outcomes suggest a relatively dominating marine source of 1291 to north Europe compared to direct gaseous releases. A transfer rate of 1291 from sea to atmosphere is derived for pertinent sea areas (English Channel, Irish Sea, and North Sea), which is estimated at 0.04 to 0.21 y(-1).

  • 27. Eriksson, A. C.
    et al.
    Nordin, E. Z.
    Nyström, Robin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Pettersson, E.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Swietlicki, E.
    Bergvall, C.
    Westerholm, R.
    Boman, Christoffer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Pagels, J. H.
    Particulate PAH Emissions from Residential Biomass Combustion: Time-Resolved Analysis with Aerosol Mass Spectrometry2014Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 48, nr 12, s. 7143-7150Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Time-resolved emissions of particulate polycyclic aromatic hydrocarbons (PAHs) and total organic particulate matter (OA) from a wood log stove and an adjusted pellet stove were investigated with high-resolution time-of-flight aerosol mass spectrometry (ANIS). The highest OA emissions were found during the addition of log wood on glowing embers, that is, slow burning pyrolysis conditions. These emissions contained about 1% PAHs (of OA). The highest PAH emissions were found during fast burning under hot air starved combustion conditions, in both stoves. In the latter case, PAHs contributed up to 40% of OA, likely due to thermal degradation of other condensable species. The distribution of PAHs was also shifted toward larger molecules in these emissions. ANIS signals attributed to PAHs were found at molecular weights up to 600 Da. The vacuum aerodynamic size distribution was found to be bimodal with a smaller mode (D-va similar to 200 nm) dominating under hot air starved combustion and a larger sized mode dominating under slow burning pyrolysis (D-va similar to 600 nm). Simultaneous reduction of PAHs, OA and total particulate matter from residential biomass combustion may prove to be a challenge for environmental legislation efforts as these classes of emissions are elevated at different combustion conditions.

  • 28. Fernández-Gómez, Cristal
    et al.
    Drott, Andreas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Björn, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Díez, Sergi
    Bayona, Josep M
    Tesfalidet, Solomon
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Lindfors, Anders
    Skyllberg, Ulf
    Towards Universal Wavelength-Specific Photodegradation Rate Constants for Methyl Mercury in Humic Waters, Exemplified by a Boreal Lake-Wetland Gradient.2013Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 47, nr 12, s. 6279-6287Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report experimentally determined first-order rate constants of MeHg photolysis in three waters along a Boreal lake-wetland gradient covering a range of pH (3.8-6.6), concentrations of total organic carbon (TOC 17.5-81 mg L(-1)), total Fe (0.8-2.1 mg L(-1)), specific UV254 nm absorption (3.3-4.2 L mg(-1) m(-1)) and TOC/TON ratios (24-67 g g(-1)). Rate constants determined as a function of incident sunlight (measured as cumulative photon flux of photosynthetically active radiation, PAR) decreased in the order dystrophic lake > dystrophic lake/wetland > riparian wetland. After correction for light attenuation by dissolved natural organic matter (DOM), wavelength-specific (PAR: 400-700 nm, UVA: 320-400 nm and UVB: 280-320 nm) first-order photodegradation rate constants (kpd) determined at the three sites were indistinguishable, with average values (±SE) of 0.0023 ± 0.0002, 0.10 ± 0.024 and 7.2 ± 1.3 m(2) E(-1) for kpdPAR, kpdUVA, and kpdUVB, respectively. The relative ratio of kpdPAR, kpdUVA, and kpdUVB was 1:43:3100. Experiments conducted at varying MeHg/TOC ratios confirm previous suggestions that complex formation with organic thiol groups enhances the rate of MeHg photodegradation, as compared to when O and N functional groups are involved in the speciation of MeHg. We suggest that if the photon fluxes of PAR, UVA, and UVB radiation are separately determined and the wavelength-specific light attenuation is corrected for, the first-order rate constants kpdPAR, kpdUVA, and kpdUVB will be universal to waters in which DOM (possibly in concert with Fe) controls the formation of ROS, and the chemical speciation of MeHg is controlled by the complexation with DOM associated thiols.

  • 29.
    Fick, Jerker
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Lindberg, Richard H
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Parkkonen, Jari
    Arvidsson, Björn
    Tysklind, Mats
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Larsson, D G Joakim
    Therapeutic levels of levonorgestrel detected in blood plasma of fish: results from screening rainbow trout exposed to treated sewage effluents2010Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 44, nr 7, s. 2661-2666Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Pharmaceuticals are found in surface waters worldwide, raising concerns about effects on aquatic organisms. Analyses of pharmaceuticals in blood plasma of fish could provide means to assess risk for pharmacological effects, as these concentrations could be compared with available human therapeutic plasma levels. In this study we investigated if fish exposed to sewage effluents have plasma concentrations of pharmaceuticals that are approaching human therapeutic levels. We also evaluated how well the bioconcentration of pharmaceuticals into fish blood plasma can be predicted based on lipophilicity. Rainbow trout were exposed to undiluted, treated sewage effluents at three sites in Sweden for 14 days. Levels of 25 pharmaceuticals in blood plasma and effluents were analyzed with liquid chromatography-mass spectrometry/mass spectrometry and gas chromatography-high resolution mass spectrometry. The progestin pharmaceutical levonorgestrel was detected in fish blood plasma at concentrations (8.5-12 ng mL(-1)), exceeding the human therapeutic plasma level. In total 16 pharmaceuticals were detected in fish plasma at concentrations higher than 1/1000 of the human therapeutic plasma concentration. Twenty-one pharmaceuticals were detected in either plasma or effluent, and 14 were detected in both compartments, allowing plasma bioconcentration factors to be determined. For 11 of these, theoretically calculated and experimentally measured values were in reasonably good agreement. However a few drugs, including levonorgestrel, did not bioconcentrate according to the screening model used. This study shows that rainbow trout exposed to sewage effluents have blood plasma levels of pharmaceuticals similar to human therapeutic concentrations, suggesting a risk for pharmacological effects in the fish. There is a particular concern about effects of progestin pharmaceuticals. For levonorgestrel, the measured effluent level (1 ng/L) was higher than water levels shown to reduce the fertility of fish.

  • 30. Flach, Carl-Fredrik
    et al.
    Genheden, Maja
    Fick, Jerker
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Larsson, D. G. Joakim
    A comprehensive screening of Escherichia coli isolates from Scandinavia's largest sewage treatment plant indicates no selection for antibiotic resistance2018Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 52, nr 19, s. 11419-11428Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    There is concern that sewage treatment plants (STPs) serve as hotspots for emergence and selection of antibiotic resistant bacteria. However, field studies investigating resistance selection by comparing bacterial populations in influents and effluents have produced variable and sometimes contradictive results. Also, large taxonomic changes between influents and effluents make interpretation of studies measuring relative gene abundances ambiguous. The aim here was to investigate whether within-species selection occurs by conducting a comprehensive screening of Escherichia coli isolated from composite influent and effluent samples collected at Scandinavia's largest STP, accompanied by analyses of antibiotics residues. In total, 4028 isolates, collected on eight occasions during 18 months, were screened for resistance to seven antibiotics. Although differences in proportions of resistant E. coli between influent and effluent samples were detected for a few antibiotics on two occasions, aggregated data over time showed no such differences for any of the investigated antibiotics. Neither was there any enrichment of multiresistant or extended-spectrum beta-lactamase-producing isolates through the treatment process. Despite some antibiotics were detected at or close to concentrations predicted to provide some selective pressure, field observations of resistance profiles in E. coli do not provide support for systematic selection in the investigated STP.

  • 31. Frankki, Sofia
    et al.
    Persson, Ylva
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Kemi.
    Tysklind, Mats
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Kemi.
    Skyllberg, Ulf
    Partitioning of CPs, PCDEs, and PCDD/Fs between particulate and experimentally enhanced dissolved natural organic matter in a contaminated soil.2006Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 40, nr 21, s. 6668-73Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We determined the distribution of hydrophobic organic contaminants (HOCs) to fractions of natural organic matter in a soil contaminated by chlorophenol wood preservatives more than 30 years ago. The concentration of dissolved organic matter (DOM) was enhanced in soil suspensions by raising pH to 6.8-9.1. After 48 h of desorption/equilibration, the DOM fraction was separated from the particulate organic matter (POM) of the soil by filtration. In the next step, DOM was flocculated by Al-nitrate, and free concentrations of HOCs were determined in the aqueous phase. The HOCs associated with DOM and POM were extracted with toluene. No significant differences in gross carbon chemistry were detected between DOM and POM, using X-ray photoelectron spectroscopy (XPS). Normalized to organic C, chlorophenols (CPs) showed a similar degree of partitioning between DOM and POM, whereas the partitioning of polychlorinated diphenyl ethers (PCDEs), polychlorinated dibenzo-p-dioxins, and furans (PCDD/Fs) was highly shifted toward POM. The partitioning to POM, relative to DOM, increased in the order PCDE < PCDF < PCDD, reflecting the hydrophobicity of the compounds.

  • 32.
    Giesler , Reiner
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi, miljö och geovetenskap.
    Björkvald , L
    Laudon , Hjalmar
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi, miljö och geovetenskap.
    Mörth , CM
    Spatial and Seasonal Variations in Stream Water delta S-34-Dissolved Organic Matter in Northern Sweden2009Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 43, nr 2, s. 447-452Artikel i tidskrift (Refereegranskat)
    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.

  • 33.
    Giesler, Reiner
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Karina, E. Clemmensen
    Wardle, David A.
    Klaminder, Jonatan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Bindler, Richard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Boreal Forests Sequester Large Amounts of Mercury over Millennial Time Scales in the Absence of Wildfire2017Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 51, nr 5, s. 2621-2627Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Alterations in fire activity due to climate change and fire suppression may have profound effects on the balance between storage and release of carbon (C) and associated volatile elements. Stored soil mercury (Hg) is known to volatilize due to wildfires and this could substantially affect the land air exchange of Hg; conversely the absence of fires and human disturbance may increase the time period over which Hg is sequestered. Here we show for a wildfire chronosequence spanning over more than 5000 years in boreal forest in northern Sweden that belowground inventories of total Hg are strongly related to soil humus C accumulation (R-2 = 0.94, p < 0.001). Our data clearly show that northern boreal forest soils have a strong sink capacity for Hg, and indicate that the sequestered Hg is bound in soil organic matter pools accumulating over millennia. Our results also suggest that more than half of the Hg stock in the sites with the longest time since fire originates from deposition predating the onset of large-scale anthropogenic emissions. This study emphasizes the importance of boreal forest humus soils for Hg storage and reveals that this pool is likely to persist over millennial time scales in the prolonged absence of fire.

  • 34.
    Haglund, Peter
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Löfstrand, Karin
    Malmvärn, Anna
    Bignert, Anders
    Asplund, Lillemor
    Temporal variations of polybrominated dibenzo-p-dioxin and methoxylated diphenyl ether concentrations in fish revealing large differences in exposure and metabolic stability2010Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 44, nr 7, s. 2466-2473Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The concentrations of polybrominated dibenzo-p-dioxins (PBDDs) and polybrominated methoxylated diphenyl ethers (MeO-PBDEs) were investigated in perch (Perca fluviatilis) collected from a Baltic Sea background contaminated area between 1990 and 2005. No temporal trend was found, but large variations were observed - up to 5-fold and 160-fold differences in MeO-PBDE and PBDD concentrations, respectively - between consecutive years, suggesting that retention of these compounds, particularly the PBDDs, is limited. Examination of the congener profiles using principal component analysis (PCA) and correlation analysis indicated that MeO-PBDEs without adjacent substituents (6-MeO-BDE47) or with two adjacent substituents (2'-MeO-BDE68 and 6-MeO-BDE90) are retained more than MeO-PBDEs with three adjacent substituents (6-MeO-BDE85 and 6-MeO-BDE99) and that 1,3,6,8-tetraBDD and 1,3,7,9-tetraBDD are retained more than the other PBDDs which have vicinal hydrogen. Debromination could explain the limited retention of 6-MeO-PBDE85 and 6-MeO-BDE99 and the absence of 2-MeO-BDE123 and 6-MeO-BDE137, and cytochrome P-450 mediated oxidation could explain the limited retention of PBDDs containing vicinal hydrogen. The levels of organobromines, especially MeO-PBDEs, were found to covary with water conditions related to primary production, for example temperature, depth visibility, and inorganic nutrient concentrations, which also favor fish productivity. The results suggest natural production of MeO-PBDEs and PBDDs and imply that they fluctuate considerably over time, as do common marine toxins in fish. Thus, assessments of human and environmental risk should consider both the average and peak concentrations of these contaminants in marine biota.

  • 35. Hale, Sarah E.
    et al.
    Lehmann, Johannes
    Rutherford, David
    Zimmerman, Andrew R.
    Bachmann, Robert T.
    Shitumbanuma, Victor
    O'Toole, Adam
    Sundqvist, Kristina L.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Arp, Hans Peter H.
    Cornelissen, Gerard
    Quantifying the Total and Bioavailable Polycyclic Aromatic Hydrocarbons and Dioxins in Biochars2012Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 46, nr 5, s. 2830-2838Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Biochar soil amendment is advocated to mitigate climate change and improve soil fertility. A concern though, is that during biochar preparation PAHs and dioxins are likely formed. These contaminants can possibly be present in the biochar matrix and even bioavailable to exposed organisms. Here we quantify total and bioavailable PAHs and dioxins in a suite of over 50 biochars produced via slow pyrolysis between 250 and 900 degrees C, using various methods and biomass from tropical, boreal, and temperate areas. These slow pyrolysis biochars, which can be produced locally on farms with minimum resources, are also compared to biochar produced using the industrial methods of fast pyrolysis and gasification. Total concentrations were measured with a Soxhlet extraction and bioavailable concentrations were measured with polyoxymethylene passive samplers. Total PAH concentrations ranged from 0.07 mu g g(-1) to 3.27 mu g g(-1) for the slow pyrolysis biochars and were dependent on biomass source, pyrolysis temperature, and time. With increasing pyrolysis time and temperature, PAH concentrations generally decreased. These total concentrations were below existing environmental quality standards for concentrations of PAHs in soils. Total PAH concentrations in the fast pyrolysis and gasification biochar were 0.3 mu g g(-1) and 45 mu g g(-1), respectively, with maximum levels exceeding some quality standards. Concentrations of bioavailable PAHs in slow pyrolysis biochars ranged from 0.17 ng L-1 to 10.0 ng L-1 which is lower than concentrations reported for relatively clean urban sediments. The gasification produced biochar sample had the highest bioavailable concentration (162 +/- 71 ng L-1). Total dioxin concentrations were low (up to 92 mu g g(-1)) and bioavailable concentrations were below the analytical limit of detection. No clear pattern of how strongly PAHs were bound to different biochars was found based on the biochars' physicochemical properties.

  • 36. Hanna, K
    et al.
    Boily, Jean-François
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Sorption of two naphthoic acids to goethite surface under flow through conditions2010Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 44, nr 23, s. 8863-8869Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    While the transport of low molecular weight organic acids was widely investigated, little is known about the mobility of the carboxylated aromatic compounds containing double rings in natural porous media. This study combines macroscopic (batch and column), microscropic (vibration spectroscopy), and surface complexation modeling to evaluate the mobility of two PAH degradation products: naphthoic acid (1-naphthoic acid (NA) and 1-hydroxy-2-naphthoic acid (HNA)), in porous media consisting of goethite-coated sand. The loss of ligands from aqueous solution was attributed to (1) a hydrogen-bonded surface complex present over the entire 3−10 pH range as well as protonated (2) surface and (3) bulk precipitates below pH 5. Mobility in column experiments was strongly affected by ligand functionality. Adsorption breakthrough predictions that make use of surface complexation parameters accurately predicted NA mobility. Those for HNA however predicted much less adsorption reactions than in the batch sorption experiments. Additional breakthrough experiments and test calculations confirmed that these differences were not related to sorption kinetics. HNA adsorption breakthrough data could only be predicted by lowering intrinsic complexation constant of the formation of hydrogen-bonded species, thereby suggesting modifications of the diffuse layer properties under flow conditions. These findings have strong implications in the assessment and prediction of contaminant transport and environmental remediation.

  • 37. Harner, T.
    et al.
    Wiberg, Karin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Norstrom, R.
    Enantiomer Fractions Are Preferred to Enantiomer Ratios for Describing Chiral Signatures in Environmental Analysis2000Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 34, nr 1, s. 218-220Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The enantiomer ratio (ER) is currently the standard descriptor of enantiomeric (chiral) signatures for environmental samples. In this paper, we argue for the adoption of the enantiomer fraction (EF) as the standard descriptor by showing drawbacks to the use of ER. The enantiomer fraction is superior because it provides a more meaningful representation of graphical data and is more easily employed in mathematical fate expressions. Several useful expressions are presented that allow EF to be used for tracking and apportioning chemical movement between environmental compartments and for investigating microbial degradation processes.

  • 38.
    Hedman, Björn
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Näslund, Morgan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Marklund, Stellan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Emission of PCDD/F, PCB, and HCB from combustion of firewood and pellets in residential stoves and boilers2006Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 40, nr 16, s. 4968-4975Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To assess potential emissions of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and hexachlorobenzene (HCB) from residential combustion of biofuels, experiments were performed in which various types of pellets and firewood were combusted in four types of stoves and boilers, with both full and reduced rates of air supply. Intermittent combustion of wood pellets resulted in emissions of 11 ng-(WHO-TEQ)/kg combusted fuel (dry weight). A modern, environmentally certified boiler yielded somewhat lower emissions of PCCD/F and PCB than a wood stove. Both gave <0.1 ng(WHO-TEQ)/m3n (1.3-6.5 ng(WHO-TEQ)/kg) and considerably lower emissions than an old boiler (7.0-13 ng(WHO-TEQ)/kg). No positive effect on emissions could be observed in full air combustion (simulating the use of a heat storage tank) compared to combustion with reduced air. Two of the wood combustion experiments included paper and plastic waste fuels. Chlorine-containing plastic waste gave rise to high emissions: ca. 310 ng(WHO-TEQ)/ kg over the whole combustion cycle. The homologue profiles of PCDD/Fs show characteristic differences between ashes and flue gas from combustions with different levels of air supply. These differences do not, however, seem to have any correlation to the relative amount of toxic congeners.

  • 39.
    Hedman, Björn
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Näslund, Morgan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Nilsson, Calle
    Marklund, Stellan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Emissions of polychlorinated dibenzodioxins and dibenzofurans and polychlorinated biphenyls from uncontrolled burning of garden and domestic waste (backyard burning)2005Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 39, nr 22, s. 8790-8796Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To assess emissions of dioxins (chlorinated dibenzodioxins and dibenzofurans) and PCB from uncontrolled domestic combustion of waste ("backyard burning"),test combustions in barrels and open fires were monitored. The waste fuels used were garden waste, paper, paper and plastic packaging, refuse-derived fuel (RDF), PVC, and electronic scrap. Combustions including PVC and electronic scrap emitted several orders of magnitude more dioxins than the other waste fuels. Emissions from the other fuels had considerable variations, but the levels were difficult to relate to waste composition. Emission factors of PCDD/F and PCB from the backyard burning ranged from 2.2 to 13 000 ng (WHO-TEQ)/kg. The levels found in ash usually were less than 5% of the total. For assessment of total emissions of dioxins and PCB from backyard burning of low and moderately contaminated wastes, an emission factor range of 4-72 ng (WHO-TEQ)/kg is suggested. These figures imply that combusting waste in the backyard could contribute substantially to total emissions, even if the amounts of fuel involved are equivalent to just a few tenths of a percent of the amounts combusted in municipal waste incinerators.

  • 40. Ilton, Eugene S
    et al.
    Boily, Jean-François
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Kemi.
    Buck, Edgar C
    Skomurski, Frances N
    Rosso, Kevin M
    Cahill, Christopher L
    Bargar, John R
    Felmy, Andrew R
    Influence of Dynamical Conditions on the Reduction of U(VI) at the Magnetite-Solution Interface2010Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 44, nr 1, s. 170-6Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The heterogeneous reduction of U(VI) to U(IV) by ferrous iron is believed to be a key process influencing the fate and transport of U in the environment. The reactivity of both sorbed and structural Fe(II) has been studied for numerous substrates, including magnetite. Published results from U(VI)-magnetite experiments have been variable, ranging from no reduction to clear evidence for the formation of U(IV). In this contribution, we used XAS and high resolution (+/-cryogenic) XPS to study the interaction of U(VI) with nanoparticulate magnetite. The results indicated that U(VI) was partially reduced to U(V) with no evidence of U(IV). However, thermodynamic calculations indicated that U phases with average oxidation states below (V) should have been stable, indicating that the system was not in redox equilibrium. A reaction pathway that involves incorporation and stabilization of U(V) and U(VI) into secondary phases is invoked to explain the observations. The results suggest an important and previously unappreciated role of U(V) in the fate and transport of uranium in the environment.

  • 41. Ilton, Eugene S
    et al.
    Wang, Zheming
    Boily, Jean-François
    Qafoku, Odeta
    Rosso, Kevin M
    Smith, Steven C
    The Effect of pH and Time on the Extractability and Speciation of Uranium(VI) Sorbed to SiO(2)2012Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 46, nr 12, s. 6604-6611Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of pH and contact time on uranium extractability from quartz surfaces was investigated using either acidic or carbonate (CARB) extraction solutions, time-delayed spikes of different U isotopes ((238)U and (233)U), and liquid helium temperature time-resolved laser-induced fluorescence spectroscopy (TRLFS). Quartz powders were reacted with (238)U(VI) bearing solutions equilibrated with atmospheric CO(2) at pH 6, 7, and 8. After 42 days, the suspensions were spiked with (233)U(VI) and reacted for an additional 7 days. Sorbed U was then extracted with either dilute nitric acid or CARB. For the CARB, but not the acid, extraction there was a systematic decrease in extraction efficiency for both isotopes from pH 6 to 8, which was mimicked by less desorption of (238)U, after the (233)U spike, from pH 6 to 8. The efficiency of (233)U extraction was consistently greater than that of (238)U, indicating a strong temporal component to the strength of U association with the surface that was accentuated with increasing pH. TRLFS revealed a strong correlation between CARB extraction efficiency and sorbed U speciation as a function of pH and time. Collectively, the observations show that aging and pH are critical factors in determining the form and strength of uranium-silica interactions.

  • 42. Jantunen, Liisa M
    et al.
    Wong, Fiona
    Gawor, Anya
    Kylin, Henrik
    Helm, Paul A
    Stern, Gary A
    Strachan, William M J
    Burniston, Deborah A
    Bidleman, Terry F
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Air Quality Processes Research Section, Environment Canada, Egbert Ontario, Canada.
    20 Years of Air-Water Gas Exchange Observations for Pesticides in the Western Arctic Ocean2015Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 49, nr 23, s. 13844-13852Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Arctic has been contaminated by legacy organochlorine pesticides (OCPs) and currently used pesticides (CUPs) through atmospheric transport and oceanic currents. Here we report the time trends and air–water exchange of OCPs and CUPs from research expeditions conducted between 1993 and 2013. Compounds determined in both air and water were trans- and cis-chlordanes (TC, CC), trans- and cis-nonachlors (TN, CN), heptachlor exo-epoxide (HEPX), dieldrin (DIEL), chlorobornanes (ΣCHBs and toxaphene), dacthal (DAC), endosulfans and metabolite endosulfan sulfate (ENDO-I, ENDO-II, and ENDO SUL), chlorothalonil (CHT), chlorpyrifos (CPF), and trifluralin (TFN). Pentachloronitrobenzene (PCNB and quintozene) and its soil metabolite pentachlorothianisole (PCTA) were also found in air. Concentrations of most OCPs declined in surface water, whereas some CUPs increased (ENDO-I, CHT, and TFN) or showed no significant change (CPF and DAC), and most compounds declined in air. Chlordane compound fractions TC/(TC + CC) and TC/(TC + CC + TN) decreased in water and air, while CC/(TC + CC + TN) increased. TN/(TC + CC + TN) also increased in air and slightly, but not significantly, in water. These changes suggest selective removal of more labile TC and/or a shift in chlordane sources. Water–air fugacity ratios indicated net volatilization (FR > 1.0) or near equilibrium (FR not significantly different from 1.0) for most OCPs but net deposition (FR < 1.0) for ΣCHBs. Net deposition was shown for ENDO-I on all expeditions, while the net exchange direction of other CUPs varied. Understanding the processes and current state of air–surface exchange helps to interpret environmental exposure and evaluate the effectiveness of international protocols and provides insights for the environmental fate of new and emerging chemicals.

  • 43.
    Jiskra, Martin
    et al.
    Soil Chemistry, Institute of Biogeochemistry and Pollutant Dynamics (IBP), ETH Zurich.
    Saile, Damian
    Soil Chemistry, Institute of Biogeochemistry and Pollutant Dynamics (IBP), ETH Zurich.
    Wiederhold, Jan G.
    Soil Chemistry, Institute of Biogeochemistry and Pollutant Dynamics (IBP), ETH Zurich.
    Bourdon, Bernard
    Laboratoire de Géologie de Lyon, ENS Lyon, France.
    Björn, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Kretzschmar, Ruben
    Soil Chemistry, Institute of Biogeochemistry and Pollutant Dynamics (IBP), ETH Zurich.
    Kinetics of Hg(II) Exchange between Organic Ligands, Goethite, and Natural Organic Matter Studied with an Enriched Stable Isotope Approach2014Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 48, nr 22, s. 13207-13217Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The mobility and bioavailability of toxic Hg(II) in the environment strongly depends on its interactions with natural organic matter (NOM) and mineral surfaces. Using an enriched stable isotope approach, we investigated the exchange of Hg(II) between dissolved species (inorganically complexed or cysteine-,EDTA-, or NOM-bound) and solid-bound Hg(II) (carboxyl-/thiol-resin or goethite) over 30 days under constant conditions (pH, Hg and ligand concentrations). The Hg(II)-exchange was initially fast, followed by a slower phase, and depended on the properties of the dissolved ligands and sorbents. The results were described by a kinetic model allowing the simultaneous determination of adsorption and desorption rate coefficients. The time scales required to reach equilibrium with the carboxylresin varied greatly from 1.2 days for Hg(OH)(2) to 16 days for Hg(II) cysteine complexes and approximately 250 days for EDTA-bound Hg(10. Other experiments could not be described by an equilibrium model, suggesting that a significant fraction of total-bound Hg was present in a non-exchangeable form (thiol-resin and NOM: 53-58%; goethite: 22-29%). Based on the slow and incomplete exchange of Hg(II) described in this study, we suggest that kinetic effects must be considered to a greater extent in the assessment of the fate of Hg in the environment and the design of experimental studies, for example, for stability constant determination or metal isotope fractionation during sorption.

  • 44.
    Jonsson, Caroline
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Persson, Per
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Sjöberg, Staffan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Loring, John
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Adsorption of Glyphosate on Goethite (α-FeOOH): surface complexation modeling combining spectroscopic and adsorption data2008Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 42, nr 7, s. 2464-2469Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    N-(phosphonomethyl)glycine (glyphosate, PMG) is the most widely used herbicide, and its adsorption onto soil minerals plays a significant role in its mobility and rate of degradation. In this work, we present the results of the first serious effort to find a realistic surface complexation model that fits both adsorption and total proton concentration data for PMG on the common soil mineral, goethite. Special attention was focused on making sure that the final model was in good semiquantitative agreement with previously reported X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopic measurements. Electrostatic effects were accounted for using the Basic Stern model, and the charges of the PMG-containing surface complexes were assumed to be distributed across the 0- and β-planes. The reactions for the protonation of the goethite surface were described using the 1 pK model. We optimized on the intrinsic formation constants and the charge distributions of the complexes, as well as the initial total proton concentration (I = 0.1 M Na(NO3), 25.0 °C), and the following model was obtained.

    Here, β is the intrinsic formation constant, Q0 is the charge at the 0-plane, and the errors are reported as one standard deviation. The charge distributions of the complexes are rationalized by considering intramolecular hydrogen bonding between the protons of the amine group and both the phosphonate and carboxylate groups.

  • 45.
    Jonsson, Sofi
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Skyllberg, Ulf
    Swedish University of Agricultural Sciences.
    Björn, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Substantial emission of gaseous monomethylmercury from contaminated water-sediment microcosms2010Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 44, nr 1, s. 278-283Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Emission rates of gaseous monomethylmercury (CH(3)Hg(II)), as well as elemental mercury (Hg(0)) and dimethylmercury [(CH(3))(2)Hg(II)], were determined in Hg-contaminated water-sediment microcosms (duplicates of three treatments) by gaseous species-specific isotope dilution analysis (SSIDA). Incubation of approximately 500 g (wet mass) of sediments containing 30 mumol of ambient Hg with an addition of 2.6 mumol of (201)Hg(II) tracer resulted in average (n = 6) gaseous emissions of 84 +/- 26, 100 +/- 37, and 830 +/- 380 pmol of ambient CH(3)Hg(II), CH(3)(201)Hg(II), and (201)Hg(0), respectively, during 108 days of incubation. In contrast to Hg(0), a transient temporal pattern was observed for measured CH(3)Hg(II) emission rates, which peaked at day 12 and decreased to much lower levels by the end of the experiments. At day 12, CH(3)Hg(II) constituted 30-50% of the total emitted gaseous Hg, emphasizing the significance of this species to total Hg emissions from anoxic sediment-water systems. Emission rates of gaseous CH(3)Hg(II) did not reflect the accumulated CH(3)Hg(II) content in the sediment, suggesting that emissions mainly originated from newly methylated Hg(II). Speciation modeling of the pore water suggests that CH(3)Hg(II) was emitted as CH(3)HgSH(0)(g).

  • 46.
    Jonsson, Sofi
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Skyllberg, Ulf
    Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Nilsson, Mats B
    Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Westlund, Per-Olof
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Shchukarev, Andrey
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Lundberg, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå marina forskningscentrum (UMF).
    Björn, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mercury methylation rates for geochemically relevant HgII species in sediments2012Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 46, nr 21, s. 11653-11659Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Monomethylmercury (MeHg) in fish from freshwater, estuarine and marine environments are a major global environmental issue. Mercury levels in biota are mainly controlled by the methylation of inorganic mercuric mercury (HgII) to MeHg in water, sediments and soils. There is, however, a knowledge gap concerning the mechanisms and rates of methylation of specific geochemical HgII species. Such information is crucial for a better understanding of variations in MeHg concentrations among ecosystems and, in particular, for predicting the outcome of currently proposed measures to mitigate mercury emissions and reduce MeHg concentrations in fish. To fill this knowledge gap we propose an experimental approach using HgII isotope tracers, with defined and geochemically important adsorbed and solid HgII forms in sediments, to study MeHg formation. We report HgII methylation rate constants, km, in estuarine sediments which span over two orders of magnitude depending on chemical form of added tracer: metacinnabar (β-201HgS(s)) < cinnabar (α-199HgS(s)) < HgII reacted with mackinawite (≡FeS-202HgII) < HgII bonded to natural organic matter (NOM-196HgII) < a typical aqueous tracer (198Hg(NO3)2(aq)). We conclude that a combination of thermodynamic and kinetic effects of HgII solid-phase dissolution and surface desorption control the HgII methylation rate in sediments and causes the large observed differences in km-values. The selection of relevant solid-phase and surface adsorbed HgII tracers will therefore be crucial to achieving biogeochemically accurate estimates of ambient HgII methylation rates.

  • 47. Josefsson, Sarah
    et al.
    Bergknut, Magnus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Futter, Martyn N.
    Jansson, Stina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Laudon, Hjalmar
    Lundin, Lisa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wiberg, Karin
    Persistent Organic Pollutants in Streamwater: Influence of Hydrological Conditions and Landscape Type2016Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 50, nr 14, s. 7416-7424Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), and hexachlorobenzene (HCB) in streamwater were measured in a remote catchment in northern Sweden and downstream to the Baltic Sea. Sampling took place at seven sites during two years and under different hydrological conditions: during the snow-free, snow-covered, and spring-flood seasons. Concentrations varied substantially between seasons and were up to 20 times higher during the spring flood compared to the preceding snow-covered period. The increase in concentrations with runoff was due to higher levels of particle-associated contaminants, while the dissolved concentrations remained stable. Particulate-contaminant concentrations were positively correlated primarily to suspended particulate matter (SPM) at sites in areas with a high land-cover fraction of sorted sediment. When upstream sampling locations were compared, a mire-dominated stream had higher concentrations and a lower retention of atmospherically deposited contaminants than a forest stream of the same catchment size. Contaminant concentrations (normalized to volume) did not increase consistently downstream despite the presence of several point sources. However, when normalized to the amount of SPM, concentrations were on average >20 times higher at the outlet in the Baltic Sea compared to the outlet from the remote catchment without point sources.

  • 48.
    Josefsson, Sarah
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Leonardsson, Kjell
    Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden.
    Gunnarsson, Jonas S
    Department of Systems Ecology, Stockholm University, SE-106 91 Stockholm, Sweden.
    Wiberg, Karin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Bioturbation-driven release of buried PCBs and PBDEs from different depths in contaminated sediments2010Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 44, nr 19, s. 7456-64Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bioturbation can remobilize previously buried contaminants, leading to an increased exposure of aquatic biota. The remobilization of buried polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) from three different sediment depth layers (2.0-2.5 cm, 5.0-5.5 cm, and 10.0-10.5 cm) was studied in a laboratory experiment with two benthic macrofauna species, the amphipod Monoporeia affinis and the polychaete Marenzelleria spp. Remobilization of PCBs and PBDEs was significantly higher in the presence of Marenzelleria spp. than in M. affinis treatments and controls (without macrofauna). The highest remobilization occurred from the most shallow layers (2.0-2.5 cm > 5.0-5.5 cm > 10.0-10.5 cm), but contaminants were remobilized due to bioturbation from layers down to at least 10 cm. Congeners with lower hydrophobicity were remobilized to a higher extent than more hydrophobic congeners. The contaminant distribution between the particulate and the dissolved phase in the water column depended on hydrophobicity and burial depth of the contaminant, with congeners from deeper layers displaying an increased distribution to the particulate phase. Release fluxes and sediment-to-water mass transfer coefficients (MTCs) show that bioturbation by the polychaete Marenzelleria spp. can lead to a significant remobilization of buried contaminants from Baltic Sea sediments.

  • 49.
    Josefsson, Sarah
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Schaanning, Morten
    Samuelsson, Göran S
    Gunnarsson, Jonas S
    Olofsson, Ida
    Eek, Espen
    Wiberg, Karin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Capping Efficiency of Various Carbonaceous and Mineral Materials for In Situ Remediation of Polychlorinated Dibenzo-p-dioxin and Dibenzofuran Contaminated Marine Sediments: Sediment-to-Water Fluxes and Bioaccumulation in Boxcosm Tests2012Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 46, nr 6, s. 3343-3351Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The efficiency of thin-layer capping in reducing sediment-to-water fluxes and bioaccumulation of polychlorinated dibenzo-p-dioxins and dibenzofurans, hexachlorobenzene, and octachlorostyrene was investigated in a boxcosm experiment. The influence of cap thickness (0.5-5 cm) and different cap materials was tested using a three-factor experimental design. The cap materials consisted of a passive material (coarse or fine limestone or a marine clay) and an active material (activated carbon (AC) or kraft lignin) to sequester the contaminants. The cap thickness and the type of active material were significant factors, whereas no statistically significant effects of the type of passive material were observed. Sediment-to-water fluxes and bioaccumulation by the two test species, the surface-dwelling Nassarius nitidus and the deep-burrowing Nereis spp., decreased with increased cap thickness and with addition of active material. Activated carbon was more efficient than lignin, and a ∼90% reduction of fluxes and bioaccumulation was achieved with 3 cm caps with 3.3% AC. Small increases in fluxes with increased survival of Nereis spp. indicated that bioturbation by Nereis spp. affected the fluxes.

  • 50.
    Kanematsu, Masakazu
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Waychunas, Glenn A.
    Boily, Jean-Francois
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Silicate Binding and Precipitation on Iron Oxyhydroxides2018Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 52, nr 4, s. 1827-1833Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Silica-bearing waters in nature often alter the reactivity of mineral surfaces via deposition of Si complexes and solids. In this work, Fourier transform infrared (FTIR) spectroscopy was used to identify hydroxo groups at goethite (alpha-FeOOH) and lepidocrocite (gamma-FeOOH) surfaces that are targeted by ligand exchange reactions with monomeric silicate species. Measurements of samples first reacted in aqueous solutions then dried under N-2(g) enabled resolution of the signature O-H stretching bands of singly (-OH), doubly (mu-OH), and triply coordinated (mu(3)-OH) groups. Samples reacted with Si for 3 and 30 d at pH 4 and 7 revealed that -OH groups were preferentially exchanged by silicate and that mu-OH and mu(3)-OH groups were not exchanged. Based on knowledge of the disposition of -OH groups on the major crystallographic faces of goethite and lepidocrocite, and the response of these groups to ligand exchange prior oligomerization, our work points to the predominance of rows of mononuclear monodentate silicate species, each separated by at least one -OH group. These species are the attachment sites from which oligomerization and polymerization reactions occur, starting at loadings exceeding similar to 1 Si/nm(2) and corresponding to soluble Si concentrations that can be as low as similar to 0.7 mM after 30 d reaction time. Only above such loadings can reaction products grow away from rows of -OH groups and form hydrogen bonds with nonexchangeable mu-OH and mu(3)-OH groups. These findings have important repercussions for our understanding of the fate of waterborne silicate ions exposed to minerals.

123 1 - 50 av 120
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf