Submitted to: SETAC Conference
Publication Type: Abstract Only
Publication Acceptance Date: May 15, 2006
Publication Date: May 24, 2006
Citation: Lizotte Jr, R.E., Moore, M.T., Smith Jr, S. Toxicity assessment of a pyrethroid insecticide mixture in a constructed wetland using hyalella azteca in laboratory tests. Abstracts of the Mid-South Regional Society of Environmental Toxicology and Chemistry Meeting. p. 21, 2006. Interpretive Summary: Abstract only. Interpretative summary not required.
Technical Abstract: A mixture of two synthetic pyrethroid insecticides, cyfluthrin and lambda-cyhalothrin, were used as model contaminants in a constructed wetland designed to mitigate runoff from an agricultural field. Both pyrethroids have widespread applications for a variety of agricultural crops and have often been used together for greater pest control. The increasing use of constructed wetlands as an additional best management practice tool for limiting potential impacts of pesticide mixtures on receiving waters presents a need to better understand the fate and effects of these chemical mixtures within these wetlands. Hyalella azteca 48 h laboratory toxicity tests within aqueous, detrital (leaf litter), and sediment phases were conducted to assess pyrethroid mixture toxicity. Water, detritus, and sediment from three wetland cells within the constructed wetland were collected and analyzed for cyfluthrin and lambda-cyhalothrin concentrations and toxicity testing on day 0 (pre-treatment), 1, 7, 13, 27, 42, and 61 (water and sediment only) days after dosing. Aqueous and detrital pyrethroid concentrations were greatest 1 to 7 days after dosing with decreasing concentrations to 61 d. Animals exposed to water and detritus from all three cells experienced near complete mortality (90-100%) to 61 d. Sediment pyrethroid concentrations were greatest 27-61 d after dosing. H. azteca exposed to sediment from the first and second wetland cells had less than 40% survival from 1-42 d with increases in survival by 61 d. Third wetland cell sediment elicited survival rates greater than or equal to 60% on 1 d, 7 d, and 42 d, coinciding with varying pyrethroid concentrations. Examination of water, detritus, and sediment contamination showed movement of pyrethroids through the wetland cells and toxicity assessments revealed H. azteca survival responses with water equal to leaf litter, which were both less than sediment.