title: Responses of phytoplankton and Hyalella azteca to agrichemical mixtures in a constructed wetland mesocosm.
abstract: 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.
authors.affiliation: National Sedimentation Laboratory, USDA-ARS , PO Box 1157, Oxford, MS 38655, USA. richard.lizotte@ars.usda.gov
authors.forename: Richard E
authors.initials: RE
authors.lastname: Lizotte
authors.forename: Sam
authors.initials: S
authors.lastname: Testa
authors.forename: Martin A
authors.initials: MA
authors.lastname: Locke
authors.forename: R Wade
authors.initials: RW
authors.lastname: Steinriede
mesh_terms: D000081:Acetamides / Q000633:toxicity; D033304:Amphipoda / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D001280:Atrazine / Q000633:toxicity; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D004784:Environmental Monitoring; D006540:Herbicides / Q000633:toxicity; D007306:Insecticides / Q000633:toxicity; D008922:Mississippi; D009584:Nitrogen / Q000633:toxicity; D026023:Permethrin / Q000633:toxicity; D010758:Phosphorus / Q000633:toxicity; D010839:Phytoplankton / Q000187:drug effects* / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D053833:Wetlands
chemical_list: D000081:Acetamides; D006540:Herbicides; D007306:Insecticides; D014874:Water Pollutants, Chemical; D002734:Chlorophyll; D010758:Phosphorus; D026023:Permethrin; D009584:Nitrogen; D001280:Atrazine; C051786:metolachlor; D000077194:Chlorophyll A