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| 2. |
- Danilov, Roman, et al.
(författare)
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The use of epiphyton and epilithon data as a base for calculating ecological indices in monitoring of eutrophication in lakes in central Sweden
- 2000
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Ingår i: Science of the Total Environment. - 0048-9697 .- 1879-1026. ; 248, s. 63-70
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Tidskriftsartikel (refereegranskat)abstract
- Eutrophication was monitored with the aid of one similarity and seven diversity indices in the lakes of different trophic levels (eutrophic, mesotrophic and oligotrophic) in central Sweden. The ecological indices were applied separately to epiphyton and epilithon communities. Epiphyton turned out to be inappropriate for assessing eutrophication in the lakes studied. On the other hand, Hurlbert's, Simpson's and the similarity indices turned out to be promising environmental tools when applied to the data of epilithon.
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| 3. |
- Aronsson, K. Andreas, et al.
(författare)
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Effects on growth, photosynthesis and pigments of the freshwater moss Fontinalis antipyretica Hedw. after exposure to wood ash solution
- 2006
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 372:1, s. 236-246
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Tidskriftsartikel (refereegranskat)abstract
- The application of wood ash from biofuel sources to the forest has been suggested as a source of nutrients for trees and for restoration of acidified soils and surface waters. Studies on the effects of wood ash on aquatic organisms and ecosystems are, however, few. This study investigated the effects of wood ash (0.1 - 10 g l-1) on the freshwater moss Fontinalis antipyretica Hedw., which has previously been shown to be a sensitive test organism for assessing environmental pollution. After nine weeks of treatment with wood ash, a significant effect of enhanced stem growth was observed at the higher concentrations (1 � 10 g l-1). The concentration of wood ash was also correlated to the growth of secondary branches. Photosynthesis (oxygen evolution after 4 h of exposure to wood ash) was significantly lower in the alkaline treatments (no pH adjustment) compared to the treatments with neutral wood ash solutions (pH adjusted to 7.5). Furthermore, photosynthesis in the alkaline wood ash treatments was significantly lower compared to the control. The ratio between the optical density value before and after acidification (OD665/665a) was higher for all wood ash concentrations compared to the control. The OD665/665a values ranged from 1.52 to 1.61 and there was a difference, however not significant, between the alkaline and the neutral treatment at 10 g l-1 wood ash. This study clearly demonstrated that wood ash may be beneficial for F. antipyretica at moderate concentrations (0.5 - 5 g l-1), particularly when sudden increase in pH is avoided.
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| 4. |
- Hrovat, B., et al.
(författare)
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Preparation of synthetic micro- and nano plastics for method validation studies
- 2024
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 925
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Tidskriftsartikel (refereegranskat)abstract
- Microplastic (MP) pollution is a persisting global problem. Accurate analysis is essential in quantifying the effects of microplastic pollution and develop novel technologies that reliably and reproducibly measure microplastic content in various samples. The most common methods for this are FTIR and Raman spectroscopy. Coloured, standardized beads are often used for method validation tests, which limits the conclusions to a very specific case rarely observed in the natural environment. This study focuses on the preparation of reference micro- and nanoplastics via cryogenic milling and shows their use for FTIR and Raman method validation studies. MPs can now be reproducibly milled from various plastics, offering the advantages of a better representation of MPs in real environment. Moreover, this study highlights issues with the current detection methods, up to now considered as the most reliable ones for MP detection and identification. Such issues, e.g. misidentification, will need to be addressed in the future. Additionally, milled MPs were used in experiments with commercial high-resolution imaging device, enabling a possible in-situ optical detection of microplastics. These experiments represent a step forward in understanding MPs in a water sample and provide a basis for a more accurate detection and identification directly from water, which would considerably reduce the time of analysis.
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| 5. |
- van Hees, Patrick, et al.
(författare)
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Aluminium speciation in forest soil solution- modelling the contribution of low molecular weight organic acids
- 2001
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Ingår i: Science Of The Total Environment. - 0048-9697. ; 278:1-3, s. 215-229
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Tidskriftsartikel (refereegranskat)abstract
- The concentrations of Al bound to identified low molecular weight organic acids (LMWOAs), phosphate and humic compounds in soil solutions (O1, O2, E, B1 and B2 horizons) from Fennoscandinavian coniferous forest soils were calculated. Two models were evaluated: WHAM (Winderemere Humic Aqueous Model) and a model treating the natural organic acids as monoprotic. The WHAM model was calibrated to find an average charge balance of unity, and then used for Al speciation. This was achieved considering approximately 80% of the natural fulvic acid to be 'active'. For the monoprotic model, constants obtained from previous fitting of soil solution data were used and the model was calibrated using acid/base titrations. The modelling confirms that the low molecular weight acids are important complex formers, binding on average 11-42% (O), 19-20% (E), and 0-30% (B) of the total Al in solution depending on the model used. The monoprotic model yielded higher concentrations than WHAM. Both models predicted that the major part of Al in solution was organically complexed to humic substances and LMWOAs, which was consistent with analytical values of 'quickly reacting' Al (monomenc inorganic forms; 12-14% of Altot on average in the E and B1 solutions). Both models could predict the magnitude of the analytical values (RMSD=4-5 μM). On average the WHAM model showed a better fit for the E horizon solutions and the monoprotic model for the upper B horizon. The pH dependence of the low molecular weight fraction of Al was modelled in the pH range 3-5.5 for a 'typical' O1 and E solution assuming no other changes in soil solution composition. The extrapolation showed that the models had a different pH dependence. The concentration of Al bound to LMWOAs in WHAM decreased with higher pH while the opposite was seen for the monoprotic model. Also the influence of the concentration of total Al in solution was modelled. The models showed similar trends but for the 'typical' O1 horizon sample the monoprotic model yielded higher concentrations of Al bound to LMWOAs than WHAM.
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