| 1. |
- Arrhenius, Åsa, 1973, et al.
(författare)
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Predictability of the mixture toxicity of 12 similarly acting congeneric inhibitors of photosystem II in marine periphyton and epipsammon communities
- 2004
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Ingår i: Aquatic Toxicology. - : Elsevier BV. - 0166-445X. ; 68:4, s. 351-367
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Tidskriftsartikel (refereegranskat)abstract
- Testing of single chemicals with single species is common ecotoxicological practice in contrast to contaminated environments where highly diverse biological communities are exposed to highly diverse mixtures of chemical compounds. We, therefore, investigated whether mixture toxicity approaches that have been used successfully for single species, might also be applied on a community level of biological complexity. Twelve inhibitors of photosystem II, selected by QSAR and chemometrical approaches as the structurally most similar from a congeneric group of phenylurea herbicides, were tested singly and as mixtures on two types of marine microalgal communities, periphyton and epipsammon. Inhibition of photosynthesis was measured in short-term tests using incorporation of radiolabelled carbon (14C) to estimate photosynthetic rates. Two basic concepts, concentration addition (CA) and independent action (IA), were used to predict the toxicities of the mixtures. Congeneric and similar-acting substances such as the phenylureas are expected to comply with CA rather than IA. The aim of the present study was to evaluate whether these concepts can be used to predict mixture toxicity also to periphyton and epipsammon photosynthesis, i.e. at the level of natural communities. We found that deviations between observed and predicted mixture toxicity were relatively small but that CA predictions were the more accurate ones. The predictions proved to be robust, when based on single substance information even from different seasons, years, and sites. We conclude that the concept of CA for predicting mixture toxicity applies also at the community level of algal testing; at least when a physiological short-term effect indicator is used that matches the mechanism of action of the substances
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| 2. |
- Backhaus, Thomas, 1967, et al.
(författare)
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Toxicity of a mixture of dissimilarly acting substances to natural algal communities: predictive power and limitations of independent action and concentration addition.
- 2004
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Ingår i: Environmental science & technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 38:23, s. 6363-70
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Tidskriftsartikel (refereegranskat)abstract
- Predictive studies of chemical mixtures are typically based on experiments with single species. To study the applicability of the concepts of independent action (IA) and concentration addition (CA) on a multispecies level, the carbon fixation of natural algal communities under toxicant exposure was studied. The presented study focused on a mixture of six dissimilarly acting substances. Conceptual reasoning as well as empirical evidence from single-species tests suggest that IA is more appropriate for this type of mixture. Nonetheless, the potential of CA was also investigated, to assess whether this concept may be applicable as a reasonable worst case prediction of mixture toxicities also on a community level. IA predicted the experimental EC50 precisely. CA underestimated the EC50 by a factor of only 1.4, although the shape of the predicted concentration-response curve was clearly different from experimental data. Hence, it can be concluded that the applicability of the concepts is not restricted to the level of single species. However, some limitations of both concepts became apparent, when stimulating (hormesis-like) effects were observed fo rtwo of the mixture components. These effects were also seen in the experimental mixture toxicity data but cannot be adequately modeled by either concept.
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| 3. |
- Dahllöf, Ingela, 1963, et al.
(författare)
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The Effect of TBT on the Structure of a Marine Sediment Community - a Boxcosm Study
- 2001
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Ingår i: Marine Pollution Bulletin. - 0025-326X .- 1879-3363. ; 42:8, s. 689-695
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Tidskriftsartikel (refereegranskat)abstract
- The effect of tri-n-butyl tin (TBT) on an intact marine sediment community after five months exposure was investigated. Changes in the structure of macro- and meiofauna communities were determined, as well as the functional diversity of the microbial community using BIOLOG microplates for Gram negative bacteria. Development of tolerance in the microbial community was investigated using Pollution Induced Community Tolerance (PICT) experiments with fluxes of nutrients as effect indicators. TBT affected the structure and recruitment of the macro- and meiofauna at nominal additions of 30137 mol TBT/m2 sediment. Number of species, diversity, biomass and community similarity was reduced at these concentrations compared to control. Species that molt seemed to be the most tolerant since they were predominant in boxes that had received the highest TBT addition and echinoderms were the most sensitive species. Renewed addition of TBT in PICT experiments with sediment from each boxcosm showed that TBT had an effect on individual nutrient fluxes from all sediments. Analyses of the flux patterns revealed a memory of previous TBT exposure, either due to induced tolerance or other community conditioning.
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| 4. |
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| 5. |
- Gustafsson, Mikael, 1965, et al.
(författare)
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Benthic foraminiferal tolerance to tri-n-butyltin (TBT)
- 2000
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Ingår i: Marine Pollution Bulletin. ; 40, s. 1072-1075
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Tidskriftsartikel (refereegranskat)abstract
- Tri-n-butyltin (TBT) has been used in the marine environment as a toxic agent in antifouling paints, but unfortunately it also has negative effects on non-target organisms in the environment. In this study, intact coastal sediment was exposed for seven months to three levels of TBT corresponding to nominal additions of 0.00, 0.02 and 2.00 nmol TBT per g dry sediment. This paper presents the first attempt to find out how living benthic foraminifera respond to TBT, Increased foraminiferal abundance in the 0.02 nmol mesocosm could be an effect of decreased predation (competition), since other representatives of meiofauna and macrofauna tended to be less tolerant to TBT, Increasing toxicity in the most contaminated mesocosm group (2.00 nmol) resulted in a less abundant foraminiferal population suggesting that TBT affects the foraminiferal community.
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| 6. |
- Porsbring, Tobias, 1974, et al.
(författare)
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Observed and predicted combination effects of the antifouling agents irgarol 1051, TBT and Sea-Nine TM 211 on the structural and functional properties of marine microalgal communities
- 2004
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Ingår i: SETAC Europe 14th Annual meeting, Prague, Czech Republic.
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Konferensbidrag (refereegranskat)abstract
- Risks of mixtures of pollutants in ecosystems cannot be assessed when chemicals are treated as acting alone. This issue is increasingly recognised, but valid and useful tools for considering mixtures are needed. However the concepts Concentration Addition (CA) and Independent Action (IA) has been shown to have potential for predicting mixture toxicities. With the aim to evaluate CA and IA under ecologically realistic conditions the antifouling agents irgarol 1051, Sea-NineTM211 and TBT were tested singly and in an equieffective mixture on marine periphyton communities in a semistatic SWIFT test. Periphyton was established on 1.5 cm2 glass discs submerged in the Gullmar fjord, Sweden and then incubated for 96 h under constant light and temperature in a medium of GF/F filtered seawater with added phosphate, nitrate and toxicant(s). Effects were then quantified by comparing analysed pigment and species composition between treatments and controls using Bray-Curtis dissimilarity index. The observed mixture effect on species composition was in perfect agreement with CA, while IA was accurate for lower observed effects but overestimated the toxicity at higher. Using pigments for predictions was found to be sensitive as this reflected lower observed effects on species composition. IA and CA are beleived to apply for mixtures of toxicants with dissimilar and similar biochemical mechanisms of action respectively and as irgarol, TBT and Sea-Nine are dissimilarly acting the most accurate prediction should be IA. However biochemical modes of action may become less relevant for predictions in an ecological context where a mode of action could be defined more by impacts on specific species and trophic levels. Results indicates that risks of mixtures should be considered and are predictable.
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| 7. |
- Rauch, Sebastien, 1971, et al.
(författare)
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Short-term toxicity and binding of platinum to freshwater periphyton communities
- 2004
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Ingår i: Archives of Environmental Contamination and Toxicology. - : Springer Science and Business Media LLC. - 0090-4341 .- 1432-0703. ; 47:3, s. 290-296
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Tidskriftsartikel (refereegranskat)abstract
- The release of platinum (Pt) from automobiles equipped with exhaust catalysts has resulted in increasing concentrations of this normally rare metal in the urban and roadside environment. Although concentrations are increasing, little is known about the environmental effects of Pt and its potential toxicity. This study was an investigation of Pt toxicity to naturally grown periphyton communities. Periphyton communities were exposed to Pt(II) and Pt(IV) in reference and stream waters. Uptake increased linearly with Pt concentration for both reference- and stream-water exposure. However, decreased photosynthetic activity was observed only for reference-water exposure. This difference was related to uptake by biotic components in reference water and binding to abiotic components in stream water.
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