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This article in JEQ

  1. Vol. 40 No. 2, p. 559-565
     
    Received: Apr 14, 2010


    * Corresponding author(s): rkroger@cfr.msstate.edu
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doi:10.2134/jeq2010.0173

Chemical Residence Time and Hydrological Conditions Influence Treatment of Fipronil in Vegetated Aquatic Mesocosms

  1. Robert Kröger *a and
  2. Matthew T. Mooreb
  1. a Dep. of Wildlife, Fisheries and Aquaculture, Box 9690, Mississippi State, MS, 39762
    b USDA–ARS, National Sedimentation Lab., Water Quality and Ecology Research Unit, PO Box 1157, Oxford, MS 38655. Assigned to Associate Editor Conrad Heatwole

Abstract

Fipronil, a phenyl-pyrazole insecticide, is often used in rice (Oryza sativa L.) production agriculture, with elevated runoff concentrations and loads having potential toxicological effects on downstream aquatic environments. This study evaluated two species of aquatic plants—broadleaf cattail (Typha latifolia L.) and powdery alligator-flag (Thalia dealbata Fraser ex Roscoe)—placed in series against a nonvegetated mesocosm in reducing concentrations and loads of fipronil, and associated metabolites. Vegetation type and hydrological condition (inundated vs. dry) were treatment effects used for comparison. The vegetated mesocosms significantly reduced higher loads and concentrations of fipronil, fipronil sulfone, and sulfide in both inundated and dry hydrological conditions over nonvegetated mesocosms. Under inundation conditions, vegetated mesocosms reduced >50% of influent fipronil concentrations and between 60 and 70% of fipronil loads, which was significantly higher than the dry conditions (10–32% concentration and load). These results show that agricultural management strategies using ephemeral aquatic zones, such as drainage ditches, can be optimized to couple chemical applications with vegetation presence and hydrology to facilitate the reduction in chemical waste loads entering downstream aquatic ecosystems. Such reduction is critical for use with fipronil, where negative impacts have been demonstrated with several nontarget species.

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Copyright © 2011. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyAmerican Society of Agronomy, Crop Science Society of America, and Soil Science Society of America