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This article in JEQ

  1. Vol. 32 No. 4, p. 1548-1556
     
    Received: June 28, 2002
    Published: July, 2003


    * Corresponding author(s): gkstearman@tntech.edu
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doi:10.2134/jeq2003.1548

Pesticide Removal from Container Nursery Runoff in Constructed Wetland Cells

  1. G. Kim Stearman *a,
  2. Dennis B. Georgea,
  3. Kris Carlsonb and
  4. Stacey Lansfordc
  1. a Center for the Management, Utilization, and Protection of Water Resources, Tennessee Technological Univ., Dixie Ave., Box 5033, Cookeville, TN 38505-0001
    b CSC Engineers, 218C E. Tremont Avenue, Charlotte, NC 28203-5364
    c Tennessee Technological Univ., Box 14638, Cookeville, TN 38505-0001

Abstract

The increased use of pesticides by container nurseries demands that practices for removal of these potential contaminants from runoff water be examined. Constructed wetlands may be designed to clean runoff water from agricultural production sites, including container nurseries. This study evaluated 14 constructed wetlands cells (1.2 by 4.9 m or 2.4 by 4.9 m, and 30 or 45 cm deep) that collected pesticide runoff from a 465-m2 gravel bed containerized nursery in Baxter, TN. One-half of the cells were vegetated with bulrush, Scirpus validus The cells were loaded at three rates or flows of 0.240, 0.120, and 0.060 m3 d−1 Herbicides—simazine (Princep) [2-chloro-4,6-bis(ethylamino)-s-triazine] and metolachlor (Pennant) [2-chloro-N-(2-ethyl-6-methylphenyl)-N-2-methoxy-1-methylethyl-acetamide]—were applied to the gravel portion of the container nursery at rates of 4.78 and 2.39 kg ha−1, respectively, 9 July 1998, and at rates of 2.39 and 1.19 kg ha−1, respectively, 17 May 1999. Pesticides entering the wetland and wetland cell water samples were analyzed daily to determine pesticide removal. At the slower flow rate, which corresponds to lower mass loading and greater hydraulic retention times (HRTs), a greater percentage of pesticides was removed. During the 2-yr period, cells with plants removed 82.4% metolachlor and 77.1% simazine compared with cells without plants, which removed 63.2% metolachlor and 64.3% simazine. At the lowest flow rate and mass loading, wetland cells removed 90.2% metolachlor and 83% simazine. Gravel subsurface flow constructed wetlands removed most of the pesticides in runoff water with the greatest removal occurring at lower flow rates in vegetated cells.

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Copyright © 2003. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyPublished in J. Environ. Qual.32:1548–1556.