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Pesticide Occurrence in Shallow Groundwater in Three Regions of Agricultural Land Use: Baldwin County, the Wiregrass Region, and the Tennessee River Valley Region of Alabama, 2009–20

Scientific Investigations Report 2024-5069
Prepared in cooperation with the Alabama Department of Agriculture and Industries
By:
https://doi.org/10.3133/sir20245069

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Abstract

As part of a cooperative investigation between the U.S. Geological Survey and the Alabama Department of Agriculture and Industries, a network of 22 groundwater wells were sampled from 2014 through 2020 for about 230 pesticide and pesticide degradate compounds. Wells were located in three regions of intensive agricultural land use in Alabama: Baldwin County, the Wiregrass region, and the Tennessee River valley region.

Metolachlor sulfonic acid, a degradate of the herbicide metolachlor, was the most frequently detected compound, occurring in about 70 percent of the samples. Three other compounds, metolachlor, atrazine, and 2-chloro-4-isopropylamino-6-amino-s-triazine, were also detected in more than half of the samples. Metolachlor and its degradates accounted for 33 of the 50 greatest compound concentrations study-wide, including the maximum pesticide concentration across all compounds (62,500 nanograms per liter). The frequency and magnitude of detections of many specific pesticide compounds varied among the three regions, but all detected pesticide concentrations were well below the U.S. Environmental Protection Agency maximum contaminant levels and applicable human health benchmarks.

Sample results were combined with results of previous (2009–13) sampling to provide a continuous time-series of data for 2009–20. More than half of the 289 pesticide compounds analyzed during 2009–20 were not detected in any samples. Only four compounds were detected at great enough frequency throughout the 10 sampling years to evaluate patterns of change through time. Metolachlor and its degradate, metolachlor sulfonic acid, were frequently detected in all regions. Atrazine and its degradate, 2-chloro-4-isopropylamino-6-amino-s-triazine, were also detected in wells from all regions, but the variability and magnitude of concentrations were greatest in the Tennessee River valley region. No apparent temporal pattern in concentrations was found.

Suggested Citation

Gill, A.C., 2024, Pesticide occurrence in shallow groundwater in three regions of agricultural land use: Baldwin County, the Wiregrass region, and the Tennessee River valley region of Alabama, 2009–20: U.S. Geological Survey Scientific Investigations Report 2024–5069, 50 p., https://doi.org/10.3133/sir20245069.

ISSN: 2328-0328 (online)

Table of Contents

  • Abstract
  • Introduction
  • Agricultural Row Crops and Estimated Pesticide Use in Study Regions
  • Methods
  • Field Tests and Nitrate Results
  • Pesticide Environmental Sampling Results, 2014–20
  • Pesticide Environmental Sampling Results, 2009–20
  • Pesticide and Degradate Detections
  • Summary and Conclusions
  • Acknowledgments
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Pesticide occurrence in shallow groundwater in three regions of agricultural land use: Baldwin County, the Wiregrass region, and the Tennessee River valley region of Alabama, 2009–20
Series title Scientific Investigations Report
Series number 2024-5069
DOI 10.3133/sir20245069
Year Published 2024
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Lower Mississippi-Gulf Water Science Center
Description Report: viii, 50 p.; Data Releases
Online Only (Y/N) Y
Google Analytic Metrics Metrics page
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