HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Google Scholar Articles by Bayless, E. R. Articles by Lampe, D. C. PubMed Articles by Bayless, E. R. Articles by Lampe, D. C. Agricola Articles by Bayless, E. R. Articles by Lampe, D. C. Related Collections Vadose Zone Processes and Chemical Transport Pesticides Best Management Practices

Simulated Fate and Transport of Metolachlor in the Unsaturated Zone, Maryland, USA

^a USGS, 5957 Lakeside Blvd., Indianapolis, IN 46278
^b USGS, 500 Pillsbury Dr., Minneapolis, MN 22807
^c USGS, 934 Broadway, Tacoma, WA 98402
^d USGS, MS 412, Denver Federal Center, Denver, CO 80225-0046
^e USGS, 1730 East Parham Rd., Richmond, VA 23228
^f USGS, 5957 Lakeside Blvd., Indianapolis, IN 46278. Commercial names are provided for purposes of identification only and should not be interpreted as an endorsement by the U.S. Geological Survey

^* Corresponding author (ebayless{at}usgs.gov).

Received for publication December 28, 2006. An unsaturated-zone transport model was used to examine the transport and fate of metolachlor applied to an agricultural site in Maryland, USA. The study site was instrumented to collect data on soil-water content, soil-water potential, ground water levels, major ions, pesticides, and nutrients from the unsaturated zone during 2002–2004. The data set was enhanced with site-specific information describing weather, soils, and agricultural practices. The Root Zone Water Quality Model was used to simulate physical, chemical, and biological processes occurring in the unsaturated zone. Model calibration to bromide tracer concentrations indicated flow occurred through the soil matix. Simulated recharge rates were within the measured range of values. The pesticide transport model was calibrated to the intensive data collection period (2002–2004), and the calibrated model was then used to simulate the period 1984 through 2004 to examine the impact of sustained agricultural management practices on the concentrations of metolachlor and its degradates at the study site. Simulation results indicated that metolachlor degrades rapidly in the root zone but that the degradates are transported to depth in measurable quantities. Simulations indicated that degradate transport is strongly related to the duration of sustained use of metolachlor and the extent of biodegradation.

Abbreviations: MESA, metolachlor ethanesulfonic acid • MOXA, metolachlor oxanilic acid • RZWQM, root zone water quality model • PRZM, pesticide root zone model

This article has been cited by other articles:

				P. D. Capel, K. A. McCarthy, and J. E. Barbash National, Holistic, Watershed-Scale Approach to Understand the Sources, Transport, and Fate of Agricultural Chemicals J. Environ. Qual., May 1, 2008; 37(3): 983 - 993. [Abstract] [Full Text] [PDF]

				T. C. Hancock, M. W. Sandstrom, J. R. Vogel, R. M.T. Webb, E. R. Bayless, and J. E. Barbash Pesticide Fate and Transport throughout Unsaturated Zones in Five Agricultural Settings, USA J. Environ. Qual., May 1, 2008; 37(3): 1086 - 1100. [Abstract] [Full Text] [PDF]

				G. V. Steele, H. M. Johnson, M. W. Sandstrom, P. D. Capel, and J. E. Barbash Occurrence and Fate of Pesticides in Four Contrasting Agricultural Settings in the United States J. Environ. Qual., May 1, 2008; 37(3): 1116 - 1132. [Abstract] [Full Text] [PDF]

				R. M. T. Webb, M. E. Wieczorek, B. T. Nolan, T. C. Hancock, M. W. Sandstrom, J. E. Barbash, E. R. Bayless, R. W. Healy, and J. Linard Variations in Pesticide Leaching Related to Land Use, Pesticide Properties, and Unsaturated Zone Thickness J. Environ. Qual., May 1, 2008; 37(3): 1145 - 1157. [Abstract] [Full Text] [PDF]