The effects of the strobilurin fungicide azoxystrobin were studied in brackish water microcosms, with natural plankton communities and sediment. Two experiments were conducted: Experiment 1 (nominal conc. 0, 15 and 60 µg/L, 24-L outdoor microcosms for 21 days) and a second, follow-up, Experiment 2 (nominal conc. 0, 3, 7.5, 15 μg/L, 4-L indoor microcosms for 12 days). The microcosms represent a simplified brackish water community found in shallow semi-enclosed coastal areas in agricultural districts in the Baltic Sea region. Measured water concentrations of the fungicide (Experiment 1) were, on average, 62 and 83% of nominal concentrations directly after application, and 22 and 26% after 21 days, for the low and high dose treatments, respectively, corresponding to mean DT50-values of 15.1 d and 25.8 d, for low and high dose treatments, respectively. In Experiment 1, direct toxic effects on calanoid copepods at both test concentrations were observed. Similarly, in Experiment 2, the copepod abundance was significantly reduced at all tested concentrations. There were also significant secondary effects on zooplankton and phytoplankton community structure, standing stocks and primary production. Very few ecotoxicological studies have investigated effects of plant protection products on Baltic organisms in general and effects on community structure and function specifically. Our results show that azoxystrobin is toxic to brackish water copepods at considerably lower concentrations than previously reported from single species tests on freshwater crustaceans, and that direct toxic effects on this ecologically important group may lead to cascade effects altering lower food webs and ecosystem functioning.

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Several current-use (≤ 80 ng g-1 dry weight) and organochlorine pesticides (≤ 15 ng g-1 dry weight) and polychlorinated biphenyls (≤ 18 ng g-1 dry weight) were found in the biodegradable fraction of source separated household waste, compost, and/or anaerobic digestate. The degradation rates of individual compounds differ depending on the treatment. Dieldrin and pentachloroaniline, e.g., degrade more rapidly than the waste is mineralized and accumulates in the products after all treatments. Many organochlorines degrade at the same rate as the waste and have the same concentrations in the waste and products. Chlorpyrifos degrades slower than the waste and accumulates in all products and ethion during anaerobic digestion. The polychlorinated biphenyls and some pesticides show different degradations rates relative the waste during different processes. Understanding the degradation of the contaminants under different conditions is necessary to develop quality criteria for the use of compost and digestate.

Question 1Yes, we believe there is an FFE. Factors such as vapour pressure and various partitioning coefficients obviously play a role, but extensive field data indicate that internal biological processes govern the physico-chemical properties of the plants and that these properties vary substantially during the year. Presently, we believe that the key factor that governs the physico-chemical properties of the plants, and hence the FFE, is the volatile compounds produced by the plants (Kylin et al. 2002; Kylin and Sjödin 2003). The amount of volatile compounds in the plants varies with season, with the result that the FFE may be quite different than what would be expected from physico-chemical calculations alone. In addition the processes are complicated by various stress factors (drought, pathogens) that may cause the amount of volatiles to vary. Question 2We are currently preparing a number of papers that indicate that there is a significant FFE Hellström et al. 2003;Kylin et al. 2002; Kylin and Sjödin 2003). Our belief that the internal volatile compounds are the key factor to understand is based on the observation from long time series in pine forests that indicate that the actual deposition of organic pollutants to the forest ecosystem is greatest during the warm summer season while very little happens during the cold winter (Kylin and Sjödin 2003). This seasonal variation in deposition can be observed also for some compounds that have the same concentrations in the air both summer and winter. Consequently, the observed deposition pattern cannot be explained by variation of the air-concentrations. Another interesting observation in these long time series is that net revolatilization from the pine needles seems to be insignificant, at least for long term processes. Instead the needles accumulate even relatively volatile persistent organic pollutants such as hexachlorocyclohexanes (HCHs) for their entire life span (Fig. 1). There is no significant loss of HCHs from the needles except in the last available year-class of needles in which the levels may decrease. This, we believe, is due to the start of senescence.The variation in deposition behaviour described above correlates well with the variation in the content of endogenous volatile organic compounds (VOCs)