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This article in JEQ

  1. Vol. 41 No. 6, p. 1806-1817
     
    Received: Jan 11, 2012
    Published: October 4, 2012


    * Corresponding author(s): sriniale@ag.tamu.edu
    Srinivasulu.Ale@gmail.com
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doi:10.2134/jeq2012.0022

Spatio-temporal Variability of Groundwater Nitrate Concentration in Texas: 1960 to 2010

  1. Sriroop Chaudhuri,
  2. Srinivasulu Ale *,
  3. Paul DeLaune and
  4. Nithya Rajan
  1. Texas A&M AgriLife Research (Texas A&M Univ. System), P.O. Box 1658, Vernon, TX 76385. Assigned to Associate Editor Pamela Rice

Abstract

Nitrate (NO3) is a major contaminant and threat to groundwater quality in Texas. High-NO3 groundwater used for irrigation and domestic purposes has serious environmental and health implications. The objective of this study was to evaluate spatio-temporal trends in groundwater NO3 concentrations in Texas on a county basis from 1960 to 2010 with special emphasis on the Texas Rolling Plains (TRP) using the Texas Water Development Board’s groundwater quality database. Results indicated that groundwater NO3 concentrations have significantly increased in several counties since the 1960s. In 25 counties, >30% of the observations exceeded the maximum contamination level (MCL) for NO3 (44 mg L−1 NO3) in the 2000s as compared with eight counties in the 1960s. In Haskell and Knox Counties of the TRP, all observations exceeded the NO3 MCL in the 2000s. A distinct spatial clustering of high-NO3 counties has become increasingly apparent with time in the TRP, as indicated by different spatial indices. County median NO3 concentrations in the TRP region were positively correlated with county-based area estimates of crop lands, fertilized croplands, and irrigated croplands, suggesting a negative impact of agricultural practices on groundwater NO3 concentrations. The highly transmissive geologic and soil media in the TRP have likely facilitated NO3 movement and groundwater contamination in this region. A major hindrance in evaluating groundwater NO3 concentrations was the lack of adequate recent observations. Overall, the results indicated a substantial deterioration of groundwater quality by NO3 across the state due to agricultural activities, emphasizing the need for a more frequent and spatially intensive groundwater sampling.

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Copyright © 2012. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.