Submitted to: Society of Environmental Toxicology and Chemistry Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: June 10, 2004
Publication Date: November 13, 2004
Citation: Lizotte Jr, R.E., Moore, M.T., Smith Jr, S., Steinriede Jr, R.W. 2004. Assessment of diazinon toxicity in a constructed wetland using hyalella azteca. Society of Environmental Toxicology and Chemistry Abstracts. p. 385. Technical Abstract: Diazinon, an organophosphate insecticide with widespread applications in agriculture and domestic use, was used as a model contaminant in a constructed wetland designed to mitigate runoff from an agricultural field. The use of constructed wetlands as mitigation systems for contaminant runoff from agricultural fields has become increasingly important. For these reasons there is a need for better understanding of the fate and effects of diazinon in these systems. The purpose of this study was to assess the mitigation of lethal acute (48 h) diazinon toxicity to Hyalella azteca within aqueous and sediment phases of a constructed wetland. Water and sediment from three individual wetland cells within a constructed wetland were analyzed for diazinon concentrations and toxicity assessments on day 0 (pretreatment), 0.3, 2, 7, 15, and 27 after dosing. Aqueous diazinon concentrations typically were greatest on day 0.3 (4-35 ppb) with decreased concentrations for the remaining sampling periods (typically <3 ppb). Animals exposed to water from all three cells experienced complete mortality 0.3 d after initial dosing with limited increases in survival (3-47%) occurring after day 15. Sediment concentrations varied spatially with measurable diazinon concentrations for two (5-6 ppb), four (6-24 ppb) and three (0.36-23 ppb) sampling periods within the first, second and third wetland cells, respectively. Animals exposed to sediment from the first wetland cell had no appreciable decrease in survival whereas survival decreased on day 2 (47%) and 7 (30 %) in wetland cells three and two, respectively. Examination of water and sediment contamination showed movement of diazinon through the wetland cells and toxicity assessments showed H. azteca survival to be more sensitive in aqueous than sediment exposures.