Laboratory Experiments Evaluating the Transport and Fate of DBCP in Hanford Sandy Loam

Abstract

AbstractSoil column, batch adsorption, and batch biodegradatian experiments were conducted to determine the fate of DBCP applied in irrigation water at low concentrations (≈ 3 µg L−1) to unsaturated Hanford sandy loam soil (coarse‐loamy, mixed, nonacid, thermic Typic Xerorthents). The objective was to determine the extent that soil might treat DBCP‐contaminated groundwater proposed for irrigation of citrus in the Redlands California area. Water applications were performed cyclically to simulate citrus irrigation practices. Volatilization of DBCP to the atmosphere between irrigations was the dominant mechanism controlling its fate once applied to the soil. Soil adsorption was found to retard the transport of DBCP 3 to 5 times when compared with the wetting front movement. Batch biodegradation experiments suggested that DBCP may also be significantly metabolized by subsurface microorganisms. The half‐life was estimated to be approximately 7 d. Soil water characteristic curve hysteresis was observed with the soil column experiments and water content distributions calculated from soil water pore pressures required that scanning curves be developed to accurately simulate experimental data.