| 1. |
- Andersson, Fräs Annika, et al.
(författare)
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Occurrence and abatement of volatile sulfur compounds during biogas production
- 2004
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Ingår i: Journal of the Air & Waste Management Association. - 1047-3289. ; 54:7, s. 855-861
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Tidskriftsartikel (refereegranskat)abstract
- Volatile sulfur compounds (VSCs) in biogas originating from a biogas production plant and from a municipal sewage water treatment plant were identified. Samples were taken at various stages of the biogas-producing process, including upgrading the gas to vehicle-fuel quality. Solid-phase microextraction was used for preconcentration of the VSCs, which were subsequently analyzed using gas chromatography in combination with mass spectrometry. Other volatile organic compounds present also were identified. The most commonly occurring VSCs in the biogas were hydrogen sulfide, carbonyl sulfide, methanethiol, dimethyl sulfide, and dimethyl disulfide, and hydrogen sulfide was not always the most abundant sulfur (S) compound. Besides VSCs, oxygenated organic compounds were commonly present (e.g., ketones, alcohols, and esters). The effect of adding iron chloride to the biogas reactor on the occurrence of VSCs also was investigated. It was found that additions of 500-g/m3 substrate gave an optimal removal of VSCs. Also, the use of a prefermentation step could reduce the amount of VSCs formed in the biogas process. Moreover, in the carbon dioxide scrubber used for upgrading the gas, VSCs were removed efficiently, leaving traces (ppbv levels). The scrubber also removed other organic compounds.
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| 2. |
- Bastviken, David, et al.
(författare)
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Measurement of methane oxidation in lakes : A comparison of methods
- 2002
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 36:15, s. 3354-3361
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Tidskriftsartikel (refereegranskat)abstract
- Methane oxidation in lakes constrains the methane emissions to the atmosphere and simultaneously enables the transfer of methane carbon to pelagic food webs, Several different methods have been used to estimate methane oxidation, but these methods have not previously been compared. In this study, we present methane oxidation estimates from three different lakes during summer and winter, using methods based on the transformation of added (CH4)-C-14, the fractionation of natural methane C-13, and the mass balance modeling of concentration gradients, All methods yielded similar results, including similar differences between lakes and seasons. Average methane oxidation rates varied from 0.25 to 81 mg of C m(-2) d(-1) and indicate that the three methods are comparable, although they to some extent take different processes into account. Critical issues as well as drawbacks and advantages with the used methods are thoroughly discussed. We conclude that methods using the stable isotope or mass balance modeling approach represent promising alternatives, particularly for studies focusing on ecosystem-scale carbon metabolism.
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| 3. |
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| 4. |
- Bastviken, David, 1971-, et al.
(författare)
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Methane as a source of carbon and energy for lake pelagic food webs
- 2003
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Ingår i: Ecology. - 0012-9658 .- 1939-9170. ; 84:4, s. 969-981
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Tidskriftsartikel (refereegranskat)abstract
- Water-column methane oxidation can represent a substantial carbon transformation pathway in lakes, and circumstantial evidence indicates that methane may be a potentially important source of carbon for pelagic food webs. We estimated methanotrophic bacterial production (MBP), methanotrophic bacterial growth efficiency (MBGE), heterotrophic bacterial production (HBP), primary production (PP), and the relative contribution of methanotrophic bacteria to overall bacterial biomass in three very different lakes during summer and winter. In addition, we measured stable carbon isotope ratios in particulate organic matter (POM), surface sediments, zooplankton, and methane. MBP corresponded to 0.3-7% of the organic C production by primary producers, and 0.5-17% of HBP during summer. During winter, MBP was 3-120% of HBP. MBP generally dominated the heterotrophic bacterial production at greater depths. Methanotrophic biomass was 3-11% of total bacterial biomass on a depth-integrated basis. Zooplankton were generally more depleted in 13C than POM. If phytoplankton d13C signatures were -35 to -30ë, such as the POM signals, observed zooplankton signatures could be explained by a fraction of 5-15% methanotrophic bacteria in their diet. The results indicate that methanotrophic bacteria can provide a significant food source for zooplankton, and that methane oxidation represents a potentially important benthic-pelagic carbon and energy link in many lakes, particularly during winter.
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| 5. |
- Bastviken, David, 1971-, et al.
(författare)
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Similar bacterial growth on dissolved organic matter in anoxic and oxic lake water
- 2001
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Ingår i: Aquatic Microbial Ecology. - : Inter-Research Science Center. - 0948-3055 .- 1616-1564. ; 24:1, s. 41-49
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Tidskriftsartikel (refereegranskat)abstract
- Anoxic metabolism yields less energy per unit substrate utilized than oxic respiration. In addition, substrate availability is believed to be reduced under anoxic conditions since oxygenases cannot be used. Consequently, it is generally assumed that bacteria grow slower in anoxic environments than in oxic environments. The results of the present study challenge this view. We compared the growth of bacterial assemblages under carbon-limited conditions in lake water under anoxic and oxic conditions. Bioassay experiments were performed with water from 3 lakes differin9 in nutrient concentrations and organic matter content. Amon9 bacteria usin9 the same source of organic matter, median anoxic growth rates were 84 to 110% of oxic growth rates. The total biomass yield durin9 the experiments did not differ between anoxic and oxic treatments. We suggest that anoxic bacterial growth was regulated by substrate availability rather than by metabolic energy yield and that availability of organic matter under anoxic conditions was equal to or even greater than that in oxic treatments. This implies that anoxic decomposition rates may actually have been faster than oxic rates.
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| 6. |
- Bastviken, David, et al.
(författare)
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Similar bacterial growth on dissolved organic matter in anoxic and oxic lake water
- 2001
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Ingår i: Aquatic Microbial Ecology. ; 24:1, s. 41-49
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Tidskriftsartikel (refereegranskat)abstract
- Anoxic metabolism yields less energy per unit substrate utilized than oxic respiration. In addition, substrate availability is believed to be reduced under anoxic conditions since oxygenases cannot be used. Consequently, it is generally assumed that bacte
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| 7. |
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| 8. |
- Björn (Fredriksson), Annika, 1972-, et al.
(författare)
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Interimreport 2 for the project on natural formation, degradation and occurrence of methyltins in different habitats. : Common project betweenRohm and Haas, former Morton Plastics Additive (MPA), Cincinnati, Ohio, USA and the Department of Water and Environmental Studies (DWES), Linköping Univeristy, Sweden.
- 2000
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Rapport (övrigt vetenskapligt/konstnärligt)
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| 9. |
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| 10. |
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