Pesticide-Contaminated Soil Sample Stability during Frozen Storage
1999
Puchalski, Michele | Horvath, Gareth | Loughran, Michael | Elsner, Gary | Koskinen, William
Little information is available in the literature on pesticide-contaminated soil sample stability during frozen storage. This research was conducted to evaluate the effects of sample holding times on frozen clay loam, clay, and loamy sand soils spiked with eight different herbicides: EPTC (S-ethyl dipropylthiocarbamate); trifluralin (α, α, α-trifluoro-2,6-dinitor-N,N-dipropyl-p-toluidine); atrazine (6-chloro-N²-ethyl-N⁴-isopropyl-1.3.5-triazine-2,4-diamine); alachlor (2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide); dicamba (3,6-dichloro-2-methoxybenzoic acid); 2,4-D (2,4-dichlorophenoxyacetic acid); silvex ((±)-2-(2,4,5-trichlorophenoxy)propionic acid); and 2,4,5-TB (4-(2,4,5-trichlorophenoxy)butanoic acid). Each soil was spiked with eight herbicides (1 mg kg⁻¹ each herbicide) and stored at −15°C for up to 450 d. The pesticides tested could generally be stored up to 450 d without affecting pesticide recovery on all soil types with the exception of trifluralin. Trifluralin decreased by 50% in the loamy sand, 40% in the clay loam, and 66% in the clay soil over the length of the study. In the loamy sand, clay loam, and clay soils a significant decrease in trifluralin concentration occurred at Day 180, 360, and 270, respectively. This study shows that long-term frozen storage can affect the sample integrity of some pesticide-contaminated soils. In addition, soil type can be a factor in sample integrity during frozen storage. Spiked controls should be a part of quality assurance and quality control during long-term frozen storage.
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