Submitted to: Archives of Environmental Contamination and Toxicology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/5/2009
Publication Date: 4/28/2009
Citation: Lizotte Jr, R.E., Knight, S.S., Bryant, C.T., Smith Jr, S. 2009. Agricultural pesticides in Mississippi Delta oxbow lake sediments during autumn and their effects on Hyalella azteca. Archives of Environmental Contamination and Toxicology. 57(3):495-503. DOI:10.1007/s0024-009-9327-6. Interpretive Summary: We examined pesticide contamination and their effects on an aquatic invertebrate animal, Hyalella azteca, in Mississippi Delta oxbow lake sediment during autumn. Sediment from three Arkansas oxbow lakes in the White River National Wildlife Refuge (WRNWR and two Mississippi oxbow lakes listed as impaired according to USEPA section 303d Clean Water Act (303d)) were collected and compared. We looked for seventeen current and historic-use pesticides and metabolites in lake sediment samples. Effects of lake sediment on survival, growth, and pesticides taken up by Hyalella azteca were examined. Sediment from all lakes had some pesticides with historic-use pesticide metabolite, p,p’-DDE found in all lakes. Animal survival was similar in mud from all lakes but animals growing in mud from one 303d lake were smaller than those from all other lakes. Only six pesticides were found in Hyalella azteca with two (dieldrin and p,p’-DDE) coinciding with differences in growth. These results are of interest to regulatory and other agencies and the pesticide industry by providing additional information to improve and sustain lake and flood plain sediment quality and overall environmental quality.
Technical Abstract: Agricultural pesticide contamination of sediments from five Mississippi Delta oxbow lakes and their effects and bioavailablity to Hyalella azteca were assessed during a low-application season, autumn. Three reference oxbow lakes were located in the White River National Wildlife Refuge (WRNWR), Arkansas, and two impaired lakes, according to USEPA section 303d Clean Water Act (303d), were located in Mississippi. Surface sediment (top 5 cm) was collected at three sites within each lake and analyzed for 17 current and historic-use pesticides and metabolites. Chronic 28-d H. azteca sediment bioassays and pesticide body residue analyses were completed to determine the degree of biological responses and bioavailability. Greatest number of detectable pesticides in WRNWR and 303d sediment samples was 9 and 12, respectively, with historic-use pesticide metabolite, p,p’-DDE ubiquitous. No significant (P > 0.05) differences in animal survival were observed among sites. Animal growth was significantly (P < 0.05) less at only one site in a 303d listed lake (Macon Lake). Only six pesticides were bioavailable to H. azteca with current-use pesticides detected at three sites, and historic-use pesticides and metabolites detected at 11 sites. Animal body residues of a historic-use pesticide (dieldrin) and metabolite (p,p’-DDE) were associated with observed growth responses. Results show limited current-use pesticide contamination of sediments and H. azteca body tissues during autumn and that bioavailable historic-use pesticides and metabolites are the primary contributors to observed biological responses.