The protection of soil ecosystems against toxic compounds is one of the main objectives in the environmental policy of the European Union. This policy has led to the successful development of soil toxicity tests for a range of soil organisms funded by the EU. So far these tests have been used to determine the effect of single compounds separately. In the field, however, soil organisms are exposed to a mixture of different toxicants at the same time. In contrast to aquatic toxicology, the ecotoxicological effects of mixtures in soil are poorly understood and data are very scarce.
Within the soil, complex interactions with the soil matrix occur due to sorption, transformation and speciation dynamics thus influencing bioavailability of mixtures. Moreover comprehensive concepts for mixture toxicity in soil are lacking which may hamper a refined and more realistic implementation of regulatory guidelines for safeguarding soil ecosystems.
The objective of this proposal is to assess the sublethal effect of toxicant mixtures on soil organisms and to look for general concepts which are applicable for different groups of compounds in soil. Recently developed sublethal soil toxicity tests using organisms with different uptake routes will be used in an integrative approach. Concepts on mixture toxicity (toxic units, funnel hypothesis and isobolographs), founded by aquatic toxicologists and pharmacologists will be used as a basis for their suitability in soil ecotoxicologal effect assessment procedures. The participants are linked together by: i) testing the same predefined mixtures (mixture 1, compounds with non-specific mode of action : copper, cadmium, lead and zinc; mixture 2, compounds with specific mode of action: carbendazim, iprodione and copper) with different invertebrate species, ii) standardized test conditions, iii) uniform measurement of chemical speciation and sorption, iv) conceptualizing and model development of effects of mixtures. The outcomes will meet the objectives mentioned in Area 18.104.22.168 of the Environment and Climate Work Programme and will provide a significant step forward in the assessment and interpretation of multiple compound effects of toxicants in soil. In addition this project focusses for the first time on sublethal effects of mixtures in contrast to acute toxicity endpoints in aquatic studies.
Funding SchemeCSC - Cost-sharing contracts
6708 PE Wageningen
223 62 Lund
EH26 0QB Penicuik
1081 HV Amsterdam