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(22-50) In situ sediment biomarkers in Chironomus riparius. Kheir, Rania*,1, Crane, Mark1, Prenner, Monika1, Maycock, Dawn1, Olsen, Tony2, Callaghan, Amanda3, 1 School of Biological Sciences, Royal Holloway University of London, Egham, UK2 Anglian Water, Huntingdon, Cambidgeshire, UK3 School of Animal and Microbial Sciences, University of Reading, Whiteknights PO Box 228, Berkshire, UK ABSTRACT- Organophosphate (OP) and carbamate (CB) insecticides are common aquatic contaminants, but rapid half-lives can make it difficult to assess their field ecotoxicity because of delays between contamination incidents, sample collection and sample bioassay. An in situ sediment exposure system was developed to help overcome these problems. This talk describes development of the in situ system and the use of acetylcholinesterase (AChE) inhibition in Chironomus riparius larvae as a specific biomarker for OP and CB insecticides. Deployment of the in situ system at uncontaminated river sites showed that AChE activity can vary twofold in the field. However, laboratory results show that even with this level of variation environmentally relevant concentrations of OPs and CBs could potentially be detected by the system. A controlled mesocosm experiment with the OP pirimphos methyl also demonstrated that the in situ system, in combination with Chironomus AChE inhibition, could identify system recovery from OP pollution. In situ sediment bioassays with biomarkers are a potentially useful method for detecting and diagnosing OP and CB pollution incidents in streams and ponds. Key words: Acetylcholinesterase, Chironomus riparius, in situ, organophosphates |
