| 1. |
- Ahlgren, Joakim, et al.
(författare)
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Sediment Depth Attenuation of Biogenic Phosphorus Compounds Measured by 31P NMR
- 2005
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Ingår i: 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
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Tidskriftsartikel (refereegranskat)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.
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| 2. |
- Ahrens, Lutz, et al.
(författare)
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Partitioning Behavior of Per- and Polyfluoroalkyl Compounds between Pore Water and Sediment in Two Sediment Cores from Tokyo Bay, Japan
- 2009
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 43:18, s. 6969-6975
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Tidskriftsartikel (refereegranskat)abstract
- The partitioning behavior of per- and polyfluoroalkyl compounds (PFCs) between pore water and sediment in two sediment cores collected from Tokyo Bay, Japan, was investigated. In addition, the fluxes and temporal trends in one dated sediment core were studied. Short-chain perfluoroalkyl carboxylic acids (PFCAs) (C ≤ 7) were found exclusively in pore water, while long-chain PFCAs (C ≥ 11) were found only in sediment. The perfluoroalkyl sulfonates (PFSAs), n-ethylperfluoro-1-octanesulfonamidoacetic acid (N-EtFOSAA), and perfluorooctane sulfonamide (PFOSA) seemed to bind more strongly to sediment than PFCAs. The enrichment of PFCs on sediment increased with increasing organic matter and decreasing pH. The perfluorocarbon chain length and functional group were identified as the dominating parameters that had an influence on the partitioning behavior of the PFCs in sediment. The maximum ΣPFC contamination in sediment was observed in 2001-2002 to be a flux of 197 pg cm-2 yr-1. Statistically significant increased concentrations in Tokyo Bay were found for perfluorooctanesulfonate (PFOS) (1956-2008), perfluorononanoic acid (PFNA) (1990-2008), and perfluoroundecanoic acid (PFUnDA) (1990-2008). Concentrations of PFOSA and N-EtFOSAA increased between 1985 and 2001, but after 2001, the concentration decreased significantly, which corresponded with the phase out of perfluorooctyl sulfonyl fluoride-based compounds by the 3M Company in 2000.
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| 3. |
- Aldén, Louise, et al.
(författare)
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No long-term persistence of bacterial pollution-induced community tolerance in tylosin-polluted soil
- 2008
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 1520-5851 .- 0013-936X. ; 42:18, s. 6917-6921
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Tidskriftsartikel (refereegranskat)abstract
- Pollution-induced community tolerance (PICT) of soil bacteria to the antibiotic tylosin was studied over 95 days. Tylosin was added at increasing concentrations, together with different amounts of alfalfa to study the effects of substrate addition on PICT and bacterial growth in soil. The leucine incorporation technique was used to estimate bacterial growth and as a detection method in the PICT concept. Direct inhibition of the bacterial growth rates, resulting in a dose-response curve, was found above 50 mg of tylosin kg(-1) of soil two days after tylosin addition (IC50 value of 960 mg tylosin kg(-1)). After 10 days of exposure to at least 50 mg of tylosin kg(-1), the PICT was observed and correlated to inhibition of bacterial growth by tylosin. A return of the PICT to control levels was found over time, and after 95 days at 1500 mg of tylosin kg(-1), essentially no PICT was found, as compared to the unpolluted control soil. The return of PICT to pre-exposure levels was not totally reflected in the recovery of bacterial growth. Alfalfa addition did not affect the inhibitory effect of tylosin on bacterial growth rates; neither did it alter the PICT. Since tylosin is relatively rapidly degraded in soil, our results indicate that the PICT will return to prepollution levels when the selective pressure of the toxicant is removed and will thus be a useful technique for monitoring remediation measures.
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| 4. |
- Anderson, Craig, 1976, et al.
(författare)
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Influence of in situ biofilm coverage on the radionuclide adsorption capacity of subsurface granite
- 2007
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 41:3, s. 830-836
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Tidskriftsartikel (refereegranskat)abstract
- Any migration of radionuclides from nuclear waste repositories is expected to be mitigated by adsorption to the host rocks surrounding hydraulically conductive fractures. Fluid rock interfaces are considered to be important barriers for nuclear waste disposal schemes but their adsorptive capacity can be affected by the growth of microbial biofilms. This study indicates that biofilms growing on fracture surfaces decrease the rocks adsorption capacity for migrating radionuclides except for trivalent species. Potential suppression of adsorption by biofilms should, therefore, be accounted for in performance safety assessment models. In this study, the adsorptive capacity of in situ anaerobic biofilms grown 450 m underground on either glass or granite slides was compared to the capacity of the same surfaces without biofilms. Surfaces were exposed to the radiotracers Co-60(II), Pm-147(III), Am-241(III), Th-234(IV), and Np-237(V) for a period of 660 h in a pH neutral anaerobic synthetic groundwater. Adsorption was investigated at multiple time points over the 660 h using liquid scintillation and ICP-MS. Results indicate that these surfaces adsorb between 0 and 85% of the added tracers under the conditions of the specific experiments. After 660 h, the distribution coefficients, R (ratio between what is sorbed and what is left in the aqueous phase), approached 3 x 10(4) m for Co-60, 3 x 10(5) m for Pm-147 and 24 'Am, I x 106 m for 234Th, and 1 x 103 m for 237Np. The highest rate of adsorption was during the first 200 h of the adsorption experiments and started to approach equilibrium after 500 h. Adsorption to colloids and precipitates contributed to decreases of up to 20% in the available Co-60, Pm-147, Am-241, and Np-237 in the adsorption systems. In the 234Th system 95% of the aqueous 234Th was removed by adsorbing to colloids. Although the range of R values for each surface tested generally overlapped, the biofilms consistently demonstrated lower R values except for the trivalant Pm-147 and Am-241 adsorption systems.
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| 5. |
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| 6. |
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| 7. |
- Armitage, James M, et al.
(författare)
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Comparative Assessment of the Global Fate and Transport Pathways of Long-chain Perfluorocarboxylic Acids (PFCAs) and Perfluorocarboxylates (PFCs) Emitted from Direct Sources
- 2009
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Ingår i: Environmental Science and Technology. - : American Chemical Society. - 0013-936X .- 1520-5851. ; 43:15, s. 5830-5836
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Tidskriftsartikel (refereegranskat)abstract
- A global-scale multispecies mass balance model was used to simulate the long-term fate and transport of perfluorocarboxylic acids (PFCAs) with eight to thirteen carbons (C8−C13) and their conjugate bases, the perfluorocarboxylates (PFCs). The main purpose of this study was to assess the relative long-range transport (LRT) potential of each conjugate pair, collectively termed PFC(A)s, considering emissions from direct sources (i.e., manufacturing and use) only. Overall LRT potential (atmospheric + oceanic) varied as a function of chain length and depended on assumptions regarding pKa and mode of entry. Atmospheric transport makes a relatively higher contribution to overall LRT potential for PFC(A)s with longer chain length, which reflects the increasing trend in the air−water partition coefficient (KAW) of the neutral PFCA species with chain length. Model scenarios using estimated direct emissions of the C8, C9, and C11 PFC(A)s indicate that the mass fluxes to the Arctic marine environment associated with oceanic transport are in excess of mass fluxes from indirect sources (i.e., atmospheric transport of precursor substances such as fluorotelomer alcohols and subsequent degradation to PFCAs). Modeled concentrations of C8 and C9 in the abiotic environment are broadly consistent with available monitoring data in surface ocean waters. Furthermore, the modeled concentration ratios of C8 to C9 are reconcilable with the homologue pattern frequently observed in biota, assuming a positive correlation between bioaccumulation potential and chain length. Modeled concentration ratios of C11 to C10 are more difficult to reconcile with monitoring data in both source and remote regions. Our model results for C11 and C10 therefore imply that either (i) indirect sources are dominant or (ii) estimates of direct emission are not accurate for these homologues.
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| 8. |
- Armitage, James M, et al.
(författare)
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Modeling the Global Fate and Transport of Perfluorooctane Sulfonate (PFOS) and Precursor Compounds in Relation to Temporal Trends in Wildlife Exposure.
- 2009
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 43:24, s. 9274-80
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Tidskriftsartikel (refereegranskat)abstract
- A global-scale fate and transport model was applied to investigate the historic and future trends in ambient concentrations of perfluorooctane sulfonate (PFOS) and volatile perfluorooctane sulfonyl fluoride (POSF)-based precursor compounds in the environment. First, a global emission inventory for PFOS and its precursor compounds was estimated for the period 1957-2010. We used this inventory as input to a global-scale contaminant fate model and compared modeled concentrations with field data. The main focus of the simulations was to examine how modeled concentrations of PFOS and volatile precursor compounds respond to the major production phase-out that occurred in 2000-2002. Modeled concentrations of PFOS in surface ocean waters are generally within a factor of 5 of field data and are dominated by direct emissions of this substance. In contrast, modeled concentrations of the precursor compounds considered in this study are lower than measured concentrations both before and after the production phase-out. Modeled surface ocean water concentrations of PFOS in source regions decline slowly in response to the production phase-out while concentrations in remote regions continue to increase until 2030. In contrast, modeled concentrations of precursor compounds in both the atmosphere and surface ocean water compartment in all regions respond rapidly to the production phase-out (i.e., decline quickly to much lower levels). With respect to wildlife biomonitoring data, since precursor compounds are bioavailable and degrade to PFOS in vivo, it is at least plausible that declining trends in PFOS body burdens observed in some marine organisms are attributable to this exposure pathway. The continued increases in PFOS body burdens observed in marine organisms inhabiting other regions may reflect exposure primarily to PFOS itself, present in the environment due to production and use of this compound as well as degradation of precursor compounds.
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| 9. |
- Armitage, James M, et al.
(författare)
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Modeling the Global Fate and Transport of Perfluorooctanoic Acid (PFOA) and Perfluorooctanoate (PFO) Emitted from Direct Sources Using a Multispecies Mass Balance Model
- 2009
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Ingår i: Environmental Science and Technology. - : American Chemical Society. - 0013-936X .- 1520-5851. ; 43:4, s. 1134-1140
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Tidskriftsartikel (refereegranskat)abstract
- The global-scale fate and transport processes of perfluorooctanoic acid (PFOA) and perfluorooctanoate (PFO) emitted from direct sources were simulated using a multispecies mass balance model over the period 1950 to 2010. The main goal of this study was to assess the atmospheric and oceanic long-range transport potential of direct source emissions and the implications for the contamination of terrestrial and marine systems worldwide. Consistent with previous modeling studies, ocean transport was found to be the dominant pathway for delivering PFO(A) associated with direct sources to the Arctic marine environment, regardless of model assumptions. The modeled concentrations for surface ocean waters were insensitive to assumptions regarding physical−chemical properties and emission mode of entry and were in reasonable agreement with available monitoring data from the Northern Hemisphere. In contrast, model outputs characterizing atmospheric transport potential were highly sensitive to model assumptions, especially the assumed value of the acid dissociation constant (pKa). However, the complete range of model results for scenarios with different assumptions about partitioning and emissions provide evidence that the atmospheric transport of directly emitted PFO(A) can deliver this substance to terrestrial environments distant from sources. Additional studies in remote or isolated terrestrial systems may provide further insight into the scale of contamination actually attributable to direct sources.
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| 10. |
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