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Assessing Aquifer Contamination Risk Using Immunoassay: Trace Analysis of Atrazine in Unsaturated Zone Sediments
Author(s) -
Juracek K. E.,
Thurman E. M.
Publication year - 1997
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1997.00472425002600040020x
Subject(s) - atrazine , environmental chemistry , contamination , dns root zone , isopropylamine , chemistry , aquifer , sediment , gas chromatography , pesticide , environmental science , soil water , groundwater , chromatography , geology , agronomy , soil science , biology , ecology , paleontology , biochemistry , geotechnical engineering
Abstract The vulnerability of a shallow aquifer in south‐central Kansas to contamination by atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamine‐ s ‐triazine) was assessed by analyzing unsaturated zone soil and sediment samples from about 60 dryland and irrigated sites using an ultrasensitive immunoassay (detection level of 0.02 µg/kg) with verification by gas chromatography/mass spectrometry (GC/MS). Samples were collected at depths of 0 to 1.2 m (i.e., the root zone), 1.2 to 1.8 m, and 1.8 to 3.0 m during two time periods—prior to planting and after harvest of crops. About 75% of the samples contained detectable concentrations of parent atrazine. At the shallow sampling depth, atrazine concentrations ranged from 0.5 to approximately 12 µg/kg. Atrazine concentrations at the intermediate (1.2–1.8 m) depth generally were <1.0 µg/kg, with most of the concentrations <0.10 µg/kg, which suggests substantial degradation of parent atrazine in the root zone. Likewise, atrazine concentrations from the deepest (1.8–3.0 m) depth ranged from <0.02 to 0.33 µg/kg. The metabolite deethylatrazine (2‐amino‐4‐chloro‐6‐isopropylamine‐ s ‐triazine) was detected by GC/MS only in 2 of 60 samples with concentrations of 1.4 and 1.5 µg/kg. The reconnaissance survey shows that, in spite of atrazine use ranging from 1 to 5 or more years, there does not appear to be a significant buildup of parent compound below the root zone. Therefore, the unsaturated zone does not appear to be a major storage compartment of atrazine contamination for the underlying shallow aquifer.