| 1. |
- Pärn, J., et al.
(författare)
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Nitrogen-rich organic soils under warm well-drained conditions are global nitrous oxide emission hotspots
- 2018
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 9:1, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- Nitrous oxide (N2O) is a powerful greenhouse gas and the main driver of stratospheric ozone depletion. Since soils are the largest source of N2O, predicting soil response to changes in climate or land use is central to understanding and managing N2O. Here we find that N2O flux can be predicted by models incorporating soil nitrate concentration (NO3 -), water content and temperature using a global field survey of N2O emissions and potential driving factors across a wide range of organic soils. N2O emissions increase with NO3 - and follow a bell-shaped distribution with water content. Combining the two functions explains 72% of N2O emission from all organic soils. Above 5 mg NO3 --N kg-1, either draining wet soils or irrigating well-drained soils increases N2O emission by orders of magnitude. As soil temperature together with NO3 - explains 69% of N2O emission, tropical wetlands should be a priority for N2O management.
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| 2. |
- Chusova, Olga, et al.
(författare)
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Biotransformation of pink water TNT on the surface of a low-cost adsorbent pine bark
- 2015
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Ingår i: Biodegradation. - : Springer Science and Business Media LLC. - 0923-9820 .- 1572-9729. ; 26:5, s. 375-386
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Tidskriftsartikel (refereegranskat)abstract
- This two-week anaerobic batch study evaluated 2,4,6-trinitrotoluene (TNT) removal efficiency from industrial pink water by (1) adsorption on low-cost adsorbent pine bark, and (2) adsorption coupled with TNT biotransformation by specialised microbial communities. Samples of the supernatant and acetonitrile extracts of pine bark were analysed by HPLC, while the composition of the bacterial community of the experimental batches, inocula and pine bark were profiled by high-throughput sequencing the V6 region of the bacterial 16S rRNA gene. Integrated adsorption and biotransformation proved to be the most efficient method for TNT removal from pink water. The type of applied inoculum had a profound effect on TNT removal efficiencies and microbial community structures, which were dominated by phylotypes belonging to the Enterobacteriaceae family. The analysis of acetonitrile extracts of pine bark supported the hypothesis that the microbial community indigenous to pine bark has the ability to degrade TNT.
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| 3. |
- Chusova, Olga, et al.
(författare)
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Effect of pine bark on the biotransformation of trinitrotoluene and on the bacterial community structure in a batch experiment
- 2014
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Ingår i: Environmental technology. - : Informa UK Limited. - 0959-3330 .- 1479-487X. ; 35:19, s. 2456-2465
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Tidskriftsartikel (refereegranskat)abstract
- Pine bark, a low-cost industrial residue, has been suggested as a promising substitute for granular activated carbon in the on-site treatment of water contaminated with 2,4,6-trinitrotoluene (TNT). However, the complex organic structure and indigenous microbial community of pine bark have thus far not been thoroughly described in the context of TNT-contaminated water treatment. This two-week batch study examined the removal efficiency of TNT from water by (1) adsorption on pine bark and (2) simultaneous adsorption on pine bark and biotransformation by specialized TNT-biotransforming microbial inocula. The bacterial community composition of experimental batches, inocula and pine bark, was profiled by Illumina sequencing of the V6 region ofthe 16S rRNA gene. The results revealed that the inocula and experimental batches were dominated by phylotypes belonging to the Enterobacteriaceae family and that the tested inocula had good potential for TNT biotransformation. The type of applied inocula had the most profound effect on the TNT-transforming bacterial community structure in the experimental batches. The indigenous microbial community of pine bark harboured phylotypes that also have a potential to degrade TNT. Altogether, the combination of a specialized inoculum and pine bark proved to be the most efficient treatment option for TNT-contaminated water.
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| 4. |
- Nõlvak, H., et al.
(författare)
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Reduction of antibiotic resistome and integron-integrase genes in laboratory-scale photobioreactors treating municipal wastewater
- 2018
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Ingår i: Water Research. - : Elsevier Ltd. - 0043-1354 .- 1879-2448. ; 142, s. 363-372
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Tidskriftsartikel (refereegranskat)abstract
- Wastewater treatment systems receiving municipal wastewater are major dissemination nodes of antibiotic resistance genes (ARGs) between anthropogenic and natural environments. This study examined the fate of antibiotic resistome and class 1–3 integron-integrase genes in photobioreactors that were treating municipal wastewater diluted (70/30) with lake or tap water for the algal biomass production. A combined approach of metagenomic and quantitative (qPCR) analysis was undertaken. Municipal wastewater treatment in the photobioreactors led to reduced antibiotic resistome proportion, number of ARG subtypes, and abundances of individual ARGs in the bacterial community. The ARGs and intI1 gene abundances and relative abundances in the discharges of the photobioreactors were either comparable or lower than the respective values in the effluents of conventional wastewater treatment plants. The reduction of the resistome proved to be strongly related to the changes in the bacterial community composition during the wastewater treatment process as it was responding to rising pH levels caused by intense algal growth. Several bacterial genera (e.g., Azoarcus, Dechloromonas, and Sulfuritalea) were recognized as potential hosts of multiple antibiotic resistance types. Although the lake water contributed a diverse and abundant resistome and intI genes profile to the treatment system, it proved to be considerably more beneficial for wastewater dilution than the tap water. The diversity (number of detected resistance types and subtypes) and proportion of the antibiotic resistome, the amount of plasmid borne integron-integrase gene reads, and the abundances and relative abundances of the majority of quantified ARGs (aadA, sul1, tetQ, tetW, qnrS, ermB, blaOXA2-type) and intI1 gene as well as the amount of multi-resistance determinants were significantly lower in the discharges of photobioreactors where lake water was used to dilute wastewater.
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| 5. |
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| 6. |
- Wulff, Angela, 1963, et al.
(författare)
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Depth distribution of photosynthetic pigments and diatoms in the sediments of a microtidal fjord
- 2005
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Ingår i: Hydrobiologia. - : Springer Science and Business Media LLC. - 0018-8158 .- 1573-5117. ; 534:1-3, s. 117-130
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Tidskriftsartikel (refereegranskat)abstract
- The depth distribution of photosynthetic pigments and benthic marine diatoms was investigated in late spring at three different sites on the Swedish west coast. At each site, sediment cores were taken at six depths (7-35 m) by scuba divers. It was hypothesized that (1) living benthic diatoms constitute a substantial part of the benthic micro. ora even at depths where the light levels are <1% of the surface irradiance, and (2) the changing light environment along the depth gradient will be reflected in ( a) the composition of diatom assemblages, and (b) different pigment ratios. Sediment microalgal communities were analysed using epifluorescence microscopy ( to study live cells), light microscopy and scanning electron microscopy ( diatom preparations), and HPLC ( photosynthetic pigments). Pigments were calculated as concentrations (mg m(-2)) and as ratios relative to chlorophyll a. Hypothesis (1) was accepted. At 20 m, the irradiance was 0.2% of surface irradiance and at 7 m, 1%. Living (epifluorescent) benthic diatoms were found down to 20 m at all sites. The cell counts corroborated the diatom pigment concentrations, decreasing with depth from 7 to 25 m, levelling out between 25 and 35 m. There were significant positive correlations between chlorophyll a and living (epifluorescent) benthic diatoms and between the diatom pigment fucoxanthin and chlorophyll a. Hypothesis (2) was only partly accepted because it could not be shown that light was the main environmental factor. A principal component analysis on diatom species showed that pelagic forms characterized the deeper locations (25-35 m), and epipelic-epipsammic taxa the shallower sites (7-20 m). Redundancy analyses showed a significant relationship between diatom taxa and environmental factors temperature, salinity, and light intensities explained 57% of diatom taxa variations.
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