| 1. |
- 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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| 2. |
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| 3. |
- Bergdahl, Ingvar A., et al.
(författare)
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Mercury in serum predicts low risk of death and myocardial infarction in Gothenburg women.
- 2013
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Ingår i: International archives of occupational and environmental health. - : Springer Science and Business Media LLC. - 1432-1246 .- 0340-0131. ; 86:1, s. 71-7
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Purpose Markers of mercury (Hg) exposure have shown both positive and negative associations with cardiovascular disease (CVD). We assessed the association between serum Hg (S–Hg) and risk of cardiovascular disease in a prospective population-based cohort, with attention to the roles of dental health and Wsh consumption. Methods Total mortality, as well as morbidity and mortality from acute myocardial infarction (AMI) and stroke, was followed up for 32 years in 1,391 women (initially age 38–60), in relation to S–Hg at baseline, using Cox regression models. Potential confounders (age, socioeconomic status, serum lipids, alcohol consumption, dental health, smoking, hypertension, waist-hip ratio, and diabetes) and other covariates (e.g., Wsh consumption) were also considered. Results Hazard ratios (HR) adjusted only for age showed strong inverse associations between baseline S–Hg and total mortality [highest quartile: hazard ratio (HR) 0.76; 95% conWdence interval (CI) 0.59–0.97], incident AMI (HR 0.56; CI 0.34–0.93), and fatal AMI (HR 0.31; CI 0.15–0.66). Adjustment for potential confounding factors, especially dental health, had a strong impact on the risk estimates, and after adjustment, only the reduced risk of fatal AMI remained statistically signiWcant. Conclusions There was a strong inverse association between Hg exposure and CVD. Likely, reasons are confounding with good dental health (also correlated with the number of amalgam Wllings in these age groups) and/or Wsh consumption. The results suggest potential eVects of dental health and/or Wsh consumption on CVD that deserve attention in preventive medicine.
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| 5. |
- Börjesson, Gunnar, et al.
(författare)
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Methane oxidation in landfill cover soils, as revealed by potential oxidation measurements and phospholipid fatty acid analyses
- 1998
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Ingår i: Soil Biology and Biochemistry. - 0038-0717. ; 30:10-11, s. 1423-1433
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Tidskriftsartikel (refereegranskat)abstract
- Landfills account for ca. 10% of the annual global burden of atmospheric methane. Part of the efflux is mitigated by means of biological methane oxidation in the landfill covers. In this study, two types of landfill cover soils (mineral soil and sewage sludge) were compared with respect to methane emissions as well as potential methane oxidation capacity and the PLFA (phospholipid fatty acid) content of soil samples. Methane fluxes were lowest at a landfill site where wastes were covered with old sewage sludge. This site consumed atmospheric methane on most occasions. In incubated soil samples from the landfill cover composed of mineral soil, potential methane oxidation was most strongly correlated with the concentration of PLFA 18:1ω8, which is typical for type-II methanotrophic bacteria. In contrast, in samples from a landfill cover composed of fresh sewage sludge, methane oxidation was most strongly correlated with 16:1-PLFAs, indicating that type-I methanotrophs predominated, probably owing to nutritional conditions being more favourable in the sludge. The results also indicate that it takes a long time, i.e. several years, for methanotrophs to get well established in landfill cover soils.
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| 6. |
- Börjesson, Gunnar, et al.
(författare)
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Microbial oxidation of CH4 at high partial pressures in an organic landfill cover soil under different moisture regimes
- 1998
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Ingår i: FEMS Microbiology Ecology. - 0168-6496. ; 26:3, s. 207-217
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Tidskriftsartikel (refereegranskat)abstract
- The uptake and utilization of CH4 at high concentrations (5-18% vol.) and different soil moistures were followed for samples from a landfill cover soil with a high organic matter content. Measurements of the utilization of CH4 and O2, and production of CO2 indicated that the activity of methanotrophic organisms accounted for most of the O2 respiration. At water saturation, CH4 oxidation rates decreased with time, probably because NH4/+ accumulated. Denitrification rates, estimated based on both N2 and N2O production, were positively related to soil moisture and only slightly influenced by the extent of CH4 oxidation. Total phospholipid fatty acid concentrations increased, and concentrations of phospholipid fatty acids, typical for obligate methanotrophic bacteria (e.g. 16:1ω8 and 18:1ω8), increased in the CH4-amended samples, indicating growth of both type I and type II methanotrophs.
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| 7. |
- Eklind, Ylva, et al.
(författare)
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Carbon Turnover and Ammonia Emissions during Composting of Biowaste at Different Temperatures
- 2007
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Ingår i: Journal of Environmental Quality. - : Wiley. - 0047-2425 .- 1537-2537. ; 36:5, s. 1512-1520
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Tidskriftsartikel (refereegranskat)abstract
- The effects of different process temperatures (40, 55, and 67°C) during composting of source-separated household waste were studied in a 200 L compost reactor at an oxygen concentration of 16%. The overall decomposition measured as carbon mineralization, decomposition of different carbon constituents, and the dynamics of nitrogen mineralization and the microbial community, are reported. Ammonia emissions at 67°C were more than double those at lower temperatures, and they were lowest at 40°C. The decomposition rate, measured as CO2 emission, was highest at 55°C. Decomposition of crude fat was slower at 40°C than at 55 and 67°C. The peak in microbial biomass was largest in the run at 40°C, where substantial differences were seen in the microbial community structure and succession compared to thermophilic temperatures. Biowaste composting can be optimized to obtain both a high decomposition rate and low ammonia emissions by controlling the process at about 55°C in the initial, high-rate stage. To reduce ammonia emissions it seems worthwhile to reduce the temperature after an initial high-temperature stage.
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| 8. |
- Håkansson, Sebastian, et al.
(författare)
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Domesticering av mikroorganismer
- 2011
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Ingår i: Genteknik som tar skruv. - 9789154060610 ; , s. 211-222
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Bokkapitel (populärvet., debatt m.m.)
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| 9. |
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| 10. |
- Johnsson, Anna-Ida, et al.
(författare)
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Development and evaluation of SCAR markers for a Pseudomonas brassicacearum strain used in biological control of snow mould
- 2009
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Ingår i: Biological Control. - : Elsevier BV. - 1049-9644 .- 1090-2112. ; 48, s. 181-187
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Tidskriftsartikel (refereegranskat)abstract
- Biological control microorganisms have long been promoted as an alternative to conventional pesticides. Before registration of a microbial biocontrol product for commercial sale, it must be evaluated as regards potential spread and persistence after release. In this study, strainspecific sequence-characterized amplified region (SCAR) markers were developed to monitor the biocontrol candidate strain Pseudomonas brassicacearum MA250, which is effective against snow mould (Microdochium nivale). One SCAR marker, OPA2-73, was used in quantitative real-time PCR (Q-PCR) on samples from a climate chamber experiment in which winter wheat seeds were treated with the bacterium or a chemical control agent, or left untreated. The results showed that MA250 persisted for up to 3 weeks after sowing on the kernel residues and also colonized the roots of treated seedlings. Total MA250 cell numbers on biocontrol treated seedlings after three weeks were approximately 10(6) Cells, compared with the original inoculum of 10(6)-10(7) cells per seed. Corresponding cell numbers of MA250 on chemically treated and untreated seedlings were below the detection limit. This study shows that SCAR marker OPA2-73 is a specific and sensitive tool for monitoring the biocontrol microorganism MA250 in environmental samples. (C) 2008 Elsevier Inc. All rights reserved.
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