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1.	Assefa, Anteneh Taye, et al. (author) Assessment of PCDD/F Source Contributions in Baltic Sea Sediment Core Records 2014 In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851 .- 1086-931X .- 1520-6912. ; 48:16, s. 9531-9539 Journal article (peer-reviewed)abstract Spatial and temporal trends of sources of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the Baltic Sea were evaluated by positive matrix factorization (PMF) and principal component analysis (PCA). Sediment cores were sampled at eight coastal, one coastal reference, and six offshore sites covering the northern to the southern Baltic Sea. The cores, which covered the period 1919-2010, were sliced into 2-3 cm disks among which 8-11 disks per core (in total 141 disks) were analyzed for all tetra- through octa-CDD/Fs. Identification and apportionment of PCDD/F sources was carried out using PMF. Five stable model PCDD/F congener patterns were identified, which could be associated with six historically important source types: (i) atmospheric background deposition (ABD), (ii) use and production of pentachlorophenol (PCP), (iii) use and production of tetra-chlorophenol (TeCP), (iv) high temperature processes (Thermal), (v) hexa-CDD-related sources (HxCDD), and (vi) chlorine-related sources (Chi), all of which were still represented in the surface layers. Overall, the last four decades of the period 1920-2010 have had a substantial influence on the Baltic Sea PCDD/F pollution, with 88 +/- 7% of the total amount accumulated during this time. The 1990s was the peak decade for all source types except TeCP, which peaked in the 1980s in the northern Baltic Sea and has still not peaked in the southern part. The combined impact of atmospheric-related emissions (ABD and Thermal) was dominant in the open sea system throughout the study period (1919-2010) and showed a decreasing south to north trend (always >80% in the south and >50% in the north). Accordingly, to further reduce levels of PCDD/Fs in the open Baltic Sea ecosystem, future actions should focus on reducing atmospheric emissions.
2.	Bidleman, Terry F., et al. (author) Atmospheric transport and deposition of bromoanisoles along a temperate to arctic gradient 2017 In: Environmental Science and Technology. - Washington : American Chemical Society (ACS). - 1086-931X .- 1520-6912 .- 0013-936X .- 1520-5851. ; 51:19, s. 10974-10982 Journal article (peer-reviewed)abstract Bromoanisoles (BAs) arise from O-methylation of bromophenols, produced by marine algae and invertebrates. BAs undergo sea-air exchange and are transported over the oceans. Here we report 2,4-DiBA and 2,4,6-TriBA in air and deposition on the Swedish west coast (Råö) and the interior of arctic Finland (Pallas). Results are discussed in perspective with previous measurements in the northern Baltic region in 2011−2013. BAs in air decreased from south to north in the order Råö > northern Baltic > Pallas. Geometric mean concentrations at Pallas increased signiﬁcantly (p < 0.05) between 2002 and 2015 for 2,4-DiBA but not for 2,4,6-TriBA. The logarithm of BA partial pressures correlated signiﬁcantly to reciprocal air temperature at the coastal station Råö and over the Baltic, but only weakly (2,4-DiBA) or not signiﬁcantly (2,4,6-TriBA) at inland Pallas. Deposition ﬂuxes of BAs were similar at both sites despite lower air concentrations at Pallas, due to greater precipitation scavenging at lower temperatures. Proportions of the two BAs in air and deposition were related to Henry’s law partitioning and source regions. Precipitation concentrations were 10−40% of those in surface water of Bothnian Bay, northern Baltic Sea. BAs deposited in the bay catchment likely enter rivers and provide an unexpected source to northern estuaries. BAs may be precursors to higher molecular weight compounds identiﬁed by others in Swedish inland lakes.
3.	Brandsma, Sicco H., et al. (author) Two organophosphorus flame retardants, resorcinol bis (diphenylphosphate)(PBDPP) and bisphenol A bis (diphenylphosphate) (BPA-BDPP) used as alternatives for BDE209 detected in dust 2013 In: Environmental Science and Technology. - : American Chemical Society (ACS). - 1086-931X .- 1520-6912 .- 0013-936X .- 1520-5851. ; 47:24, s. 14434-14441 Journal article (peer-reviewed)abstract Resorcinol bis(diphenylphosphate) (RBDPP) and bisphenol A bis(diphenylphosphate) (BPA-BDPP) are two halogen-free organophosphorus flame retardant (PFRs) that are used as an alternative for the decabromodiphenyl ether (Deca-BDE) technical mixture in TV/flatscreen housing and other electronic consumer products.' In this study, dust samples were collected from various microenvironments in The Netherlands (houses, cars), Greece.(houses), and Sweden (apartments, cars, furniture stores, electronics stores) and analyzed for RBDPP and BPA-BDPP. Additionally, the dust samples from The Netherlands were analyzed for decabromodiphenyl ether (BDE-209) for comparison and for TPHP, which is a byproduct in the RBDPP and BPA-BDPP technical products. BPA-BDPP was detected in almost all dust samples from The Netherlands, Greece, and Sweden. Highest concentrations were found in dust samples collected on electronic equipment from all three countries with BPA-BDPP levels ranging from <0.1 to 1300 mu g/g and RBDPP levels from <0.04 to 520 mu g/g. RBDPP and BPA-BDPP levels in dust collected further away from the electronics (source) were usually lower. BDE-209 levels in The Netherlands dust samples collected on and around the electronics were similar and much lower than the BPA-BDPP/RBDPP levels, indicating that the electronics were not the source of BDE-209. Strong positive correlations were found between TPHP concentrations and those of RBDPP (r = 0.805) and BPA-BDPP (r = 0.924), probably due to TPHP being a byproduct in commercial RBDPP and BPA-BDPP mixtures in electronics. To our knowledge, this is the first time that RBDPP and BPA-BDPP were detected in dust samples from Europe.
4.	Börjesson, Gunnar, et al. (author) Methane fluxes from a Swedish landfill determined by geostatistical treatment of static chamber measurements 2000 In: Environmental Science and Technology. - : American Chemical Society (ACS). - 1086-931X .- 1520-6912 .- 0013-936X .- 1520-5851. ; 34:18, s. 4044-4050 Journal article (peer-reviewed)abstract Methane emissions from a Swedish landfill were measured with a static chamber technique on three occasions during 1997. Methane flux rates ranged from -15.2 x 10-3 to 40 g of CH4 m-2 h-1, and the spatial variability was high (CV = 343-386%). The spatial distribution of the emissions was estimated with the help of ordinary kriging, which is a spatial interpolation method. Three different approaches to estimate the total amounts were used: kriging on logarithm-transformed data, kriging with extremes excluded, and linear interpolation of measurements. These were compared between themselves and with the flux rates measured with a tracer gas technique. While the latter gave an estimate of 41 kg of CH4 h-1 from the landfill (with small variations), the highest possible estimate obtained with static chambers and geostatistical methods was 9.7 kg of CH4 h-1. The conclusion is that static chambers can hardly be trusted for making more than small-scale estimates of landfill gas emissions.Methane emissions from a Swedish landfill were measured with a static chamber technique on three occasions during 1997. Methane flux rates ranged from -15.2 ╫ 10-3 to 40 g of CH4 m-2 h-1, and the spatial variability was high (CV = 343-386%). The spatial distribution of the emissions was estimated with the help of ordinary kriging, which is a spatial interpolation method. Three different approaches to estimate the total amounts were used: kriging on logarithm-transformed data, kriging with extremes excluded, and linear interpolation of measurements. These were compared between themselves and with the flux rates measured with a tracer gas technique. While the latter gave an estimate of 41 kg of CH4 h-1 from the landfill (with small variations), the highest possible estimate obtained with static chambers and geostatistical methods was 9.7 kg of CH4 h-1. The conclusion is that static chambers can hardly be trusted for making more than small-scale estimates of landfill gas emissions.
5.	Destouni, G., et al. (author) General quantification of catchment-scale nutrient and pollutant transport through the subsurface to surface and coastal waters 2010 In: Environmental Science and Technology. - : American Chemical Society (ACS). - 1086-931X .- 1520-6912 .- 0013-936X .- 1520-5851. ; 44:6, s. 2048-2055 Journal article (peer-reviewed)abstract This study develops a general quantification framework for consistent intermodel and intercatchment comparison of the nutrient and pollutant mass loading from multiple sources in a catchment area to downstream surface and coastal waters. The framework accounts for the wide spectrum of different transport pathways and travel times through the subsurface (soil, groundwater, sediment) and the linked surface (streams, lakes, wetlands) water systems of a catchment. The account is based on key flow partitioning and mass delivery fractions, which can be quantified differently by different flow and transport and reaction models. The framework application is exemplified for two Swedish catchment cases with regard to the transport of phosphorus and of a generic attenuating solute. The results show essential differences in model quantifications of transport pathways and temporal spreading, with important implications for our understanding of cause and effect in the catchment-scale nutrient and pollutant loading to downstream waters.
6.	Drake, Henrik, 1979-, et al. (author) Incorporation of Metals into Calcite in a Deep Anoxic Granite Aquifer 2018 In: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851 .- 1086-931X .- 1520-6912. ; 52:2, s. 493-502 Journal article (peer-reviewed)abstract Understanding metal scavenging by calcite in deep aquifers in granite is of importance for deciphering and modeling hydrochemical fluctuations and water rock interaction in the upper crust and for retention mechanisms associated With underground, repositories for toxic wastes. Metal scavenging into calcite has generally been established in the laboratory or in natural environments that cannot be unreservedly applied to conditions in deep crystalline rocks, an environment of broad interest, for nuclear waste repositories. Here, we report a microanalytical study: of calcite precipitated over a period of 17 years from anoxic, low-temperature (14 degrees C), neutral (pH: 7.4-7.7), and brackish (Cl: 1700-7100 mg/L) groundwater flowing in fractures at >400 m depth in granite rock. This enabled assessment of the trace metal uptake by calcite under these deep-seated conditions. Aquatic speciation modeling was carried out to assess influence of metal complexation on the partitioning into calcite. The resulting environment-specific partition coefficients were for several divalent ions in line with values obtained in controlled laboratory experiments, whereas for several other ions they differed substantially. High absolute uptake of rare earth elements and U(IV) suggests that coprecipitation into calcite can be an important sink for these metals and analogousactinides in the vicinity of geological repositories.
7.	Ejlertsson, Jörgen, et al. (author) Anaerobic Degradation of Nonylphenol Mono- and Diethoxylates in Digestor Sludge, Landfilled Municipal Solid Waste, and Landfilled Sludge 1999 In: Environmental Science and Technology. - : American Chemical Society (ACS). - 1086-931X .- 1520-6912 .- 0013-936X .- 1520-5851. ; 33:2, s. 301-306 Journal article (peer-reviewed)abstract The aim of this study was to investigate the extent to which anaerobic digestor sludge, landfilled sludge, and landfilled municipal solid waste (MSW) degrade NPEOs under methanogenic conditions. NPEO1 and NPEO2 (NPEO1-2), used in a mixture, were chosen as model compounds. Anaerobic experimental bottles were amended with 100% digestor sludge at three different concentrations of NPEO1-2: 2, 60, and 308 mg L-1. [U-14C]-NPEO1-2 was used to detect any possible decomposition of the aromatic moiety of the NPEO1-2. All inoculates used degraded NPEO1-2 at 2 mg L-1, with nonylphenol (NP) forming the ultimate degradation product. The NP formed was not further degraded, and the incubations with labeled NPEO showed that the aromatic structure remained intact. Both landfill inoculates also transformed NPEO1-2 at 60 mg L-1. CH4 production was temporarily hampered in bottles with MSW landfill inoculum at 60 and 308 mg L-1. With 2 mg L-1 of NPEO, CH4 production closely followed that in the controls. Both NP and NPEO1-2 interacted with the organic matter which resulted in sorption to the solid phase.
8.	Galle, Bo, et al. (author) Measurements of Methane Emissions from Landfills Using a Time Correlation Tracer Method Based on FTIR Absorption Spectroscopy 2000 In: Environmental Science and Technology. - : American Chemical Society (ACS). - 1086-931X .- 1520-6912 .- 0013-936X .- 1520-5851. ; 35:1, s. 21-25 Journal article (peer-reviewed)
9.	Kim, Jihee, et al. (author) Mass Budget of Methylmercury in the East Siberian Sea: The Importance of Sediment Sources 2020 In: Environmental Science and Technology. - : American Chemical Society (ACS). - 1086-931X .- 1520-6912 .- 0013-936X .- 1520-5851. Journal article (peer-reviewed)abstract Biological concentrations of methylmercury(MeHg) are elevated throughout the Arctic Ocean; however, to date, the major sources and the spatial variability of MeHg are not well quantified. To identify the major inputs and outputs of MeHg to the Arctic shelf water column, we measured MeHg concentrations in the seawater and sediment samples from the East Siberian Sea collected from August to September 2018. We found that the MeHg concentrations in seawater and pore water were higher on the slope than on the shelf, while the MeHg concentrations in the sediment were higher on the shelf than on the slope. We created a mass budget for MeHg and found that the benthic diffusion and resuspension largely exceed other sources, such as atmospheric deposition and river water input. The major sinks of MeHg in the water column were dark demethylation and evasion. When we extrapolated our findings on benthic diffusion to the entire Arctic shelf system, the annual MeHg diffusion from the shelf sediments was estimated to be 23,065 ± 939 mol yr−1, about 2 times higher than previously proposed river discharges. Our study suggests that the MeHg input from shelf sediments in the Arctic Ocean is significant and has been previously underestimated.
10.	Lemieux, Christine L, et al. (author) Cancer Risk Assessment of Polycyclic Aromatic Hydrocarbon Contaminated Soils Determined Using Bioassay-Derived Levels of Benzo[a]pyrene Equivalents 2015 In: Environmental Science and Technology. - : American Chemical Society (ACS). - 1086-931X .- 1520-6912 .- 0013-936X .- 1520-5851. ; 49:3, s. 1797-1805 Journal article (peer-reviewed)abstract Here we evaluate the excess lifetime cancer risk (ELCR) posed by 10 PAH-contaminated soils using (i) the currently advocated, targeted chemical-specific approach that assumes dose additivity for carcinogenic PAHs and (ii) a bioassay-based approach that employs the in vitro mutagenic activity of the soil fractions to determine levels of benzo[a]pyrene equivalents and, by extension, ELCR. Mutagenic activity results are presented in our companion paper.1 The results show that ELCR values for the PAH-containing fractions, determined using the chemical-specific approach, are generally (i.e., 8 out of 10) greater than those calculated using the bioassay-based approach; most are less than 5-fold greater. Only two chemical-specific ELCR estimates are less than their corresponding bioassay-derived values; differences are less than 10%. The bioassay-based approach, which permits estimation of ELCR without a priori knowledge of mixture composition, proved to be a useful tool to evaluate the chemical-specific approach. The results suggest that ELCR estimates for complex PAH mixtures determined using a targeted, chemical-specific approach are reasonable, albeit conservative. Calculated risk estimates still depend on contentious PEFs and cancer slope factors. Follow-up in vivo mutagenicity assessments will be required to validate the results and their relevance for human health risk assessment of PAH-contaminated soils
11.	Lim, Hwanmi, et al. (author) Detection of Benz[j]aceanthrylene in Urban Air and Evaluation of Its Genotoxic Potential 2015 In: Environmental Science and Technology. - Stockholm : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 49:5, s. 3101-3109 Journal article (peer-reviewed)abstract Benz[j]aceanthrylene (B[j]A) is a cyclopenta-fused polycyclic aromatic hydrocarbon with strong mutagenic and carcinogenic effects. We have identified B[j]A in air particulate matter (PM) in samples collected in Stockholm, Sweden and in Limeira, Brazil using LC-GC/MS analysis. Determined concentrations ranged between 1.57 and 12.7 and 19.6-30.2 pg/m(3) in Stockholm and Limeira, respectively, which was 11-30 times less than benzo[a]pyrene (B[a]P) concentrations. Activation of the DNA damage response was evaluated after exposure to B[j]A in HepG2 cells in comparison to B[a]P. We found that significantly lower concentrations of B[j]A were needed for an effect on cell viability compared to B[a]P, and equimolar exposure resulted in significant more DNA damage with B[j]A. Additionally, levels of gamma H2AX, pChk1, p53, pp53, and p21 proteins were higher in response to B[j]A than B[a]P. On the basis of dose response induction of pChk1 and gamma H2AX, B[j]A potency was 12.5- and 33.3-fold higher than B[a]P, respectively. Although B[j]A levels in air were low, including B[j]A in the estimation of excess lifetime cancer risk increased the risk up to 2-fold depending on which potency factor for B[j]A was applied. Together, our results show that B[j]A could be an important contributor to the cancer risk of air PM.
12.	Lindström, David, et al. (author) Chromium(III) and Chromium(VI) Surface Treated Galvanized Steel for Outdoor Constructions : Environmental Aspects 2010 In: Environmental Science and Technology. - : American Chemical Society (ACS). - 1086-931X .- 1520-6912 .- 0013-936X .- 1520-5851. ; 44:11, s. 4322-4327 Journal article (peer-reviewed)abstract The long-term degradation of chromium(III) (Zn-Cr(III)) and chromium(VI)-based (Zn-Cr(VI)) surface treatments on galvanized steel and their capacities to hinder the release of zinc induced by atmospheric corrosion at non-sheltered urban and marine exposure conditions for two years are investigated. Compared to bare zinc sheet, both surface treatments revealed high corrosion protection abilities and capacities to hinder the release of zinc, still evident after two years of exposure. The zinc barrier properties of the thinner Zn-Cr(VI) (10 nm) treatment were during the first 100 days of urban exposure slightly improved compared with Zn-Cr(III) (35 nm). However, their long-term protection capacities were inversed. Released concentrations of total chromium correspond to annual release rates less than 0.000032 (Zn-Cr(III)) and 0.00014 g Cr m-2yr-1 (Zn-Cr(VI)) after one year of urban exposure. Ageing by indoor storage of the surface treatments prior to outdoor exposure reduced the released Cr concentrations from the surface treatments. No Cr(VI) was released from the aged surfaces but from the freshly exposed Zn-Cr(VI). Marine exposure conditions resulted in a faster reduction of chromate to chromium(III)oxide compared with urban conditions, and a significantly lower amount of both chromium(III) and chromium(VI) released from Zn-Cr(VI) at the marine site compared with the urban site.
13.	Merritt, Anne-Sophie, et al. (author) Cat and house dust mite allergen content is stable in frozen dust over time 2013 In: Environmental Science and Technology. - Stockholm : Karolinska Institutet, Dept of Medical Epidemiology and Biostatistics. - 0013-936X .- 1520-5851. Journal article (peer-reviewed)abstract Background: Dust from indoor environments consists of animal allergens, pollen, endotoxins and other substances which may exacerbate symptoms in sensitive individuals. In prospective cohort studies, dust is often collected from indoor environments in order to assess allergen exposure and possible relationships to health outcomes. Typically, large numbers of samples are collected and kept frozen until further analysis, sometimes several years later. To date, there is insufficient knowledge about what happens to the dust and its contents during storage. Objectives: In the present study, our aim was to analyse allergen content over a 30 month period frozen dust collected from beds in homes in order to simulate a study design of exposure assessment commonly used in epidemiological studies. Methods: Thirty-seven dust samples from mattresses in homes were collected using a Duststream dust collector. Each dust sample was subdivided into six aliquots. One tube (baseline) was extracted and analysed for cat and HDM allergen content using ELISA, all other tubes were stored at -80°C until further handling. Approximately every six months (6, 12, 18 and 30 months), dust from one tube was thawed, extracted and analysed the same way. Data was log-transformed and analysed using linear regression. Results: No trend for decreasing or increasing cat (p=0.606) or house dust mite (p=0.928)allergen levels could be observed over time. Levels of cat allergen were considerably higher in mattresses from homes with cats compared to homes without cats (p<0.001). Conclusion: It is important to assess the allergen stability in dust before designing costly and labour-intensive studies of allergen exposure and health outcomes, commonly used in environmental epidemiology. Although the present study showed that cat and HDM allergens 3 remained stable in dust stored at -80°C during a 2.5 year period, analyses of other allergens or substances in frozen dust is desirable as well as evaluating the effect of longer storage times.
14.	Plassmann, Merle M., et al. (author) Theoretical and Experimental Simulation of the Fate of Semifluorinated n-Alkanes during Snowmelt 2010 In: Environmental Science and Technology. - : American Chemical Society (ACS). - 1086-931X .- 1520-6912 .- 0013-936X .- 1520-5851. ; 44:17, s. 6692-6697 Journal article (peer-reviewed)abstract Semifluorinated n-alkanes (SFAs) are highly fluorinated anthropogenic chemicals that are released into the environment through their use in ski waxes. Nothing is known about their environmental partitioning in general and their fate during snowmelt in particular. Properties were estimated for a range of SFAs with different chain lengths and degrees of fluorination using the SPARC calculator and poly parameter linear free energy relationships (ppLFERs). The calculations resulted in very low water solubility and vapor pressures and, consequently, high log KOW and log KOA values. Artificially produced snow in a cold room was spiked with a range of SFAs and subsequently melted with infrared lamps. Melt water, particles, and air samples taken during melting were analyzed. Both calculations and experiments showed that SFAs used in ski waxes will bind to particles or snow grain surfaces during snowmelt and thus are predicted to end up on the soil surface in skiing areas.
15.	Sun, Jiachen, et al. (author) Hepatic Fatty Acid Profiles Associated with Exposure to Emerging and Legacy Halogenated Contaminants in Two Harbor Seal Populations across the North Atlantic 2022 In: Environmental Science and Technology. - : American Chemical Society (ACS). - 1086-931X .- 1520-6912 .- 0013-936X .- 1520-5851. ; 56:3, s. 1830-1840 Journal article (peer-reviewed)abstract Fatty acids (FAs) have been extensively used as indicators of foraging ecology in marine mammals, yet their association with exposure to contaminants has rarely been investigated. The present study provided the first characterization of the relationship between hepatic FA profiles and exposure to a suite of contaminants in a sentinel species─the harbor seal (Phoca vitulina)─from the Gulf of Maine and the south coast of Sweden. FA profiles differed in the two seal populations, and the levels of legacy and alternative brominated flame retardants and polyhalogenated carbazoles were significantly elevated in Maine seals. Correlations between individual FAs and multiple flame retardants (FRs) and poly- and perfluoroalkyl substances (PFASs) were found in seals from both populations. Moreover, several FR and PFAS chemicals were significantly associated with the estimated desaturating enzyme activity inferred from the FA profiles. The ratios of poly to monounsaturated FAs (∑PUFAs/∑MUFAs) and those of unsaturated to saturated FAs (∑UFAs/∑SFAs) were significantly associated with HBBZ, PFHxS, or BDE 47 in seals from Maine and Sweden, whereas ∑n – 6/∑n – 3 PUFAs was significantly associated with BDE 154 and 36-CCZ in Swedish and Maine seals, respectively. Our results suggest the lipid metabolism-disrupting potential of these contaminants in marine mammals and warrant continuous biomonitoring and risk assessment, considering the critical role of PUFAs in vital biological processes.
16.	Undeman, Emma, et al. (author) The susceptibility of human populations to environmental exposure to organic contaminants 2010 In: Environmental Science and Technology. - Washington, D.C. : American Chemical Society. - 1086-931X .- 1520-6912 .- 0013-936X .- 1520-5851. ; 44:16, s. 6249-6255 Journal article (peer-reviewed)abstract Environmental exposure to organic contaminants is a complex function of environmental conditions, food chain characteristics, and chemical properties. In this study the susceptibility of various human populations to environmental exposure to neutral organic contaminants was compared. An environmental fate model and a linked bioaccumulation model were parameterized to describe ecosystems in different climatic regions (temperate, arctic, tropical and steppe). The human body burden resulting from constant emissions of hypothetical chemicals was estimated for each region. An exposure susceptibility index was defined as the body burden in the region of interest normalized to the burden of the same chemical in a reference human from the temperate region eating an average diet. For most persistent chemicals emitted to air, the Arctic had the highest susceptibility index (max 520). Susceptibility to exposure was largely determined by the food web properties. The properties of the physical environment only had a marked effect when air or water, not food, was the dominant source of human exposure. Shifting the mode of emission markedly changed the relative susceptibility of the ecosystems in some cases. The exposure arising from chemical use clearly varies between ecosystems, which makes an understanding of ecosystem susceptibility to exposure important for chemicals management.
17.	Achermann, Stefan, et al. (author) Trends in Micropollutant Biotransformation along a Solids Retention Time Gradient 2018 In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 52:20, s. 11601-11611 Journal article (peer-reviewed)abstract For many polar organic micropollutants, biotransformation by activated sludge microorganisms is a major removal process during wastewater treatment. However, our current understanding of how wastewater treatment operations influence microbial communities and their micropollutant biotransformation potential is limited, leaving major parts of observed variability in biotransformation rates across treatment facilities unexplained. Here, we present biotransformation rate constants for 42 micropollutants belonging to different chemical classes along a gradient of solids retention time (SRT). The geometric mean of biomass-normalized first-order rate constants shows a clear increase between 3 and 15 d SRT by 160% and 87%, respectively, in two experiments. However, individual micropollutants show a variety of trends. Rate constants of oxidative biotransformation reactions mostly increased with SRT. Yet, nitrifying activity could be excluded as primary driver. For substances undergoing other than oxidative reactions, i.e., mostly substitution-type reactions, more diverse dependencies on SRT were observed. Most remarkably, characteristic trends were observed for groups of substances undergoing similar types of initial transformation reaction, suggesting that shared enzymes or enzyme systems that are conjointly regulated catalyze biotransformation reactions within such groups. These findings open up opportunities for correlating rate constants with measures of enzyme abundance such as genes or gene products, which in turn should help to identify enzymes associated with the respective biotransformation reactions.
18.	Adediran, Gbotemi A., et al. (author) Microbial Biosynthesis of Thiol Compounds : Implications for Speciation, Cellular Uptake, and Methylation of Hg(II) 2019 In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 53:14, s. 8187-8196 Journal article (peer-reviewed)abstract 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)2 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)2 complexes. The Hg(II) methylation rate across different Hg(LMM-RS)2 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.
19.	Adolfsson-Erici, Margaretha, et al. (author) Internal Benchmarking Improves Precision and Reduces Animal Requirements for Determination of Fish Bioconcentration Factors 2012 In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 46:15, s. 8205-8211 Journal article (peer-reviewed)abstract The enactment of new chemical regulations has generated a large need for the measurement of the fish bioconcentration factor (BCF). Past experience shows that the BCF determination lacks precision, requires large numbers of fish, and is costly. A new protocol was tested that shortens the experiment from up to 12 weeks for existing protocols to 2 weeks and reduces the number of fish by a factor of 5, while introducing internal benchmarking for the BCF determination. Rainbow trout were simultaneously exposed to 11 chemicals. The BCFs were quantified using one of the test chemicals, musk xylene, as a benchmark. These were compared with BCFs measured in a parallel experiment based on the OECD 305 guideline. The agreement was <20% for five chemicals and between 20%-25% for two further, while two chemicals lay outside the BCF operating window of the experiment and one was lost due to analytical difficulties. This agreement is better than that observed in a BCF Gold Standard Database. Internal benchmarking allows the improvement of the precision of BCF determination in parallel to large reduction in costs and fish requirements.
20.	Aeppli, Christoph, et al. (author) Chlorine Isotope Effects and Composition of Naturally Produced Organochlorines from Chloroperoxidases, Flavin-Dependent Halogenases, and in Forest Soil 2013 In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 47:13, s. 6864-6871 Journal article (peer-reviewed)abstract The use of stable chlorine isotopic signatures (delta Cl-37) of organochlorine compounds has been suggested as a tool to determine both their origins and transformations in the environment. Here we investigated the delta Cl-37 fractionation of two important pathways for enzymatic natural halogenation: chlorination by chloroperoxidase (CPO) and flavin-dependent halogenases (FDH). Phenolic products of CPO were highly Cl-37 depleted (delta Cl-37 = -12.6 +/- 0.9 parts per thousand); significantly more depleted than all known industrially produced organochlorine compounds (delta Cl-37 = -7 to +6 parts per thousand). In contrast, four FDH products did not exhibit any observable isotopic shifts (delta Cl-37 = -0.3 +/- 0.6 parts per thousand). We attributed the different isotopic effect to the distinctly different chlorination mechanisms employed by the two enzymes. Furthermore, the delta Cl-37 in bulk organochlorines extracted from boreal forest soils were only slightly depleted in Cl-37 relative to inorganic Cl. In contrast to previous suggestions that CPO plays a key role in production of soil organochlorines, this observation points to the additional involvement of either other chlorination pathways, or that dechlorination of naturally produced organochlorines can neutralize delta Cl-37 shifts caused by CPO chlorination. Overall, this study demonstrates that chlorine isotopic signatures are highly useful to understand sources and cycling of organochlorines in nature. Furthermore, this study presents delta Cl-37 values of FDH products as well of bulk organochlorines extracted from pristine forest soil for the first time.
21.	Aeppli, Christoph, et al. (author) Use of Cl and C Isotopic Fractionation to Identify Degradation and Sources of Polychlorinated Phenols : Mechanistic Study and Field Application 2013 In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 47:2, s. 790-797 Journal article (peer-reviewed)abstract 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-CSLA) 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.
22.	Agathokleous, E., et al. (author) Rethinking Subthreshold Effects in Regulatory Chemical Risk Assessments 2022 In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 56:16, s. 11095-11099 Journal article (peer-reviewed)
23.	Agrell, Cecilia, et al. (author) Evidence of Latitudinal Fractionation of Polychlorinated Biphenyl Congeners along the Baltic Sea Region 1999 In: Environmental Science & Technology. - : American Chemical Society (ACS). - 1520-5851 .- 0013-936X. ; 33:8, s. 1149-1156 Journal article (peer-reviewed)abstract Annual cycles of the atmospheric concentrations of PCBs were determined at 16 (mostly rural) stations around the Baltic Sea between 1990 and 1993. The concentration levels of individual congeners were found to be influenced by their physical-chemical properties, ambient temperature, and geographical location. Median levels of PCBs were similar at all stations except at one urban site near Riga. A latitudinal gradient with higher levels in the south was found for the sum of PCB as well as for individual congeners, and the gradient was more pronounced for the low volatility congeners. As a result, the high volatility congeners increased in relative importance with latitude. Generally, PCB concentrations increased with temperature, but slopes of the partial pressure in air versus reciprocal temperature were different between congeners and between stations. In general, the low volatility congeners were more temperature dependent than the high volatility PCB congeners. Steep slopes at a sampling location indicate that the concentration in air is largely determined by diffusive exchange with soils. Lack of a temperature dependence may be due to the influence of long-range transported air masses at remote sites and due to the episodic or random nature of PCB sources at urban sites.
24.	Ahlgren, Joakim, et al. (author) Sediment Depth Attenuation of Biogenic Phosphorus Compounds Measured by 31P NMR 2005 In: Environmental Science and Technology. - Univ Uppsala, Dept Analyt Chem, SE-75124 Uppsala, Sweden. Univ Uppsala, Dept Ecol & Evolut, Uppsala, Sweden. Univ Uppsala, Dept Organ Chem, SE-75124 Uppsala, Sweden. : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 39:3, s. 867-872 Journal article (peer-reviewed)abstract 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 31P 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, 31P NMR is a useful tool to asses the bioavailability of certain P compound groups, and the combination with traditional fractionation techniques makes quantification possible.
25.	Ahrens, Lutz (author) Characterization of Two Passive Air Samplers for Per- and Polyfluoroalkyl Substances 2013 In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 47, s. 14024-14033 Journal article (peer-reviewed)abstract Two passive air sampler (PAS) media were characterized under field conditions for the measurement of per- and polyfluoroalkyl substances (PFASs) in the atmosphere. The PASs, consisting of polyurethane foam (PUF) and sorbent-impregnated PUF (SIP) disks, were deployed for over one year in parallel with high volume active air samplers (HV-AAS) and low volume active air samplers (LV-AAS). Samples were analyzed for perfluoroalkyl carboxylic acids (PFCAs), perfluoroalkane sulfonic acids (PFSAs), fluorotelomer alcohols (FTOHs), fluorotelomer methacrylates (FTMACs), fluorotelomer acrylates (FTACs), perfluorooctane sulfonamides (FOSAs), and perfluorooctane sulfonamidoethanols (FOSEs). Sampling rates and the passive sampler medium (PSM)-air partition coefficient (KPSM-A) were calculated for individual PFASs. Sampling rates were similar for PFASs present in the gas phase and particle phase, and the linear sampling rate of 4 m(-3) d(-1) is recommended for calculating effective air sample volumes in the SIP-PAS and PUF-PAS for PFASs except for the FOSAs and FOSEs in the PUF-PAS. SIP disks showed very good performance for all tested PFASs while PUF disks were suitable only for the PFSAs and their precursors. Experiments evaluating the suitability of different isotopically labeled fluorinated depuration compounds (DCs) revealed that C-13(8)-perfluorooctanoic acid (PFOA) was suitable for the calculation of site-specific sampling rates. Ambient temperature was the dominant factor influencing the seasonal trend of PFASs.

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