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Bioavailability of pesticides in freshwater sediments

the importance of sorption and uptake routes

Åkerblom, Nina (2007). Bioavailability of pesticides in freshwater sediments. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2007:3
ISBN 91-576-7302-2
[Doctoral thesis]

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In ecological risk assessment standardized sediment toxicity tests are used to predict the hazard of chemicals for sediment-living organisms. Feeding is a prerequisite in these long-term tests to avoid starvation of test organisms. Therefore, added food particles may act as vectors for the test compound. The importance of food particles as vectors, however, is dependent on several factors, for example, sorption and major uptake routes. In this thesis, laboratory experiments on the importance of pesticide sorption and uptake routes for the bioavailability to the midge Chironomus riparius in sediment toxicity test setups were performed. A feeding selectivity study showed that larvae almost exclusively fed on added food particles, and highly neglected sediment particles. Additionally, experiments on the sorption of the insecticide lindane, showed that food and peat particles (used in artificial sediment) efficiently sorbed lindane (>95% after 48 h). The binding strength of lindane was weak, facilitating particulate uptake. However, the uptake from dissolved lindane was higher than the uptake from particles. From this we concluded that toxicity may be underestimated in spiked-sediment scenarios, where hydrophobic pesticides sorb to the sediment and larvae to a large extent feed on uncontaminated food particles. Conversely, in a spiked-water scenario, the food particles may act as vector, resulting in a facilitated particulate uptake, in addition to the uptake from water. Sediment organic matter affects sorption, and thus bioavailability of pesticides. Pyrethroid toxicity was much higher in artificial sediment than in a natural sediment, indicating the simplicity and shortcomings of using artificial sediments. Interestingly, the sediment quality highly affected bioavailability in spiked-water. For example, C. riparus larvae in sediments with low organic matter content and exposed to spiked-water pyrethroids, showed lower survival, slower development, and increased adult size, than those in sediments with higher organic matter. The pyrethroid deltamethrin, showed an LC50-value (28 d) for C. riparius larvae in artificial sediment of 16 pg/L and 11 µg/kg for water- and sediment exposures, respectively, i.e. toxic effects occurred at concentrations lower than the detection limits for high-tech analytical methods. This thesis contributes to a wider understanding of processes affecting bioavailability in freshwater sediments, and in particular in standardized sediments used in toxicity testing. The understanding of test compound sorption and bioavailability is crucial for sound interpretations of toxicity tests and for the general credibility of such tests.

Authors/Creators:Åkerblom, Nina
Title:Bioavailability of pesticides in freshwater sediments
Subtitle:the importance of sorption and uptake routes
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2007
Number of Pages:36
ALLI. Åkerblom, N. and Goedkoop, W. 2003. Stable isotopes and fatty acids reveal that Chironomus riparius feeds selectively on added food in standardized toxicity tests. Environmental Toxicology and Chemistry 22 (7), 1473-1480. II. Åkerblom, N., Goedkoop, W., Nilsson, T., and Kylin, H. Sorption and desorption of lindane in standardized toxicity tests with Chironomus riparius - High resolution studies of compound-particle interactions and bioavailability. (Submitted manuscript) III. Åkerblom, N., Arbjörk, C., Hedlund, M., and Goedkoop, W. Deltamethrin toxicity to the midge Chironomus riparius Meigen - Effects of exposure scenario and sediment quality. (Submitted manuscript) IV. Goedkoop, W., Spann N., and Åkerblom, N. Sublethal cypermethrin concentrations affect mean development rate and adult size in the midge Chironomus riparius Meigen. (Manuscript)
Place of Publication:Uppsala
ISBN for printed version:91-576-7302-2
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:sediment, toxicity, testing, chironomus riparius, organic matter, pesticides, lindane, pyrethrins, deltamethrin, bioavailability, sorption, desorption, bioaccumulation
Keywords:artificial sediment, toxicity tests, Chironomus riparius, bioavailability, pesticides, sorption, desorption, uptake route
Permanent URL:
ID Code:1308
Department:(NL, NJ) > Dept. of Environmental Assessment (until 080831)
Deposited By: Nina Åkerblom
Deposited On:11 Jan 2007 00:00
Metadata Last Modified:02 Dec 2014 10:11

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