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Responses of Phytoplankton and Hyalella azteca to Agrichemical Mixtures in a Constructed Wetland Mesocosm

Lizotte, Richard E., Jr., Testa, Sam, III, Locke, Martin A., Steinriede, R. Wade, Jr.
Archives of environmental contamination and toxicology 2013 v.65 no.3 pp. 474
Hyalella azteca, agricultural runoff, agricultural watersheds, atrazine, bioassays, constructed wetlands, environmental impact, metolachlor, nitrogen, nutrients, permethrin, phosphorus, phytoplankton, pollutants, sediments, toxicity, trapping
We assessed the capability of a constructed wetland to mitigate toxicity of a variety of possible mixtures, such as nutrients only (NO) (nitrogen [N], phosphorus [P]), pesticides only (PO) (atrazine, S-metolachlor, permethrin), and nutrients + pesticides on phytoplankton chlorophyll-a, on 48-h aqueous Hyalella azteca survival and 10-day sediment H. azteca survival and growth. Water and sediment were collected at 10-, 20-, and 40-m distances from inflow and analyzed for nutrients, pesticides, chlorophyll-a, and H. azteca laboratory bioassays. Phytoplankton chlorophyll-a increased 4- to 10 -fold at 7 days after NO treatment. However, responses of chlorophyll-a to PO and nutrients + pesticides were more complex with associated decreases at only 20 m for pesticides only and 10 and 40 m for nutrients + pesticides treatments. H. azteca aqueous survival decreased within the first 48 h of dosing at 10- and 20-m distances during PO and nutrients + pesticides treatments in association with permethrin concentrations. H. azteca sediment survival was unaffected, whereas 10-day growth decreased within 1 day of dosing at all sites during nutrients + pesticides treatment. Constructed wetlands were shown to be an effective agricultural best-management tool for trapping pollutants and mitigating ecological impacts of run-off in agricultural watersheds.