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D. B. Hatfield

Publications and source records attributed to D. B. Hatfield.

7 recordsLinked to original sources
USGS1988

Distribution of selenium in soils of agricultural fields, western San Joaquin Valley, California

Soils from three agricultural fields in the Panoche Creek alluvial fan area in the western San Joaquin Valley, California, were analyzed for soluble, adsorbed, and total concentrations of selenium (Se) to assess the distribution and forms of Se in relation to the leaching of Se from soils. This assessment is needed to evaluate the importance of soil Se in affecting ground water concentrations. Soil samples were collected from three fields with drainage systems of different ages (6, 15, 1.5 yr) and different Se concentrations in drain water (58, 430, 3700 µg L −1 , respectively). Concentrations of soluble Se and salinity were highest in soils from the field drained for 1.5 yr and lowest in the field drained for 6 yr. Of the total concentration of soil Se from all three fields, the proportion of adsorbed and soluble Se ranged from 1 to 11% and <1 to 63%, respectively. Most of the soluble Se was present as selenate and most of the adsorbed Se was found to be selenite. Consistent with a model of evaporative concentration of Se and salinity in soils and shallow ground water in this area, most of the variance in soluble Se is explained by salinity (r 2 > 0.68) in saturation extracts of soils sampled from below the water table. In contrast, most soluble salts and Se apparently have been leached from the unsaturated soils in the fields drained for 6 and 15 yr. For the leached soils, dissolution and precipitation of evaporite minerals containing Se may no longer control concentrations of soluble Se.

California↗
USGS1987

Distribution of selenium in soils of agricultural fields, western San Joaquin Valley, California

Soils from three agricultural fields in the western San Joaquin Valley were analyzed for soluble, adsorbed, and total concentrations of selenium (Se) to assess the distribution and forms of Se, and the relation of the distribution and forms of Se to the leaching of Se from soils. Soil samples were collected in three fields with drainage systems of different ages (6, 15, 1.5 yr) and different Se concentrations in drain water (58, 430, 3700 micrograms/L respectively). Preliminary methods to determine total Se and estimate adsorbed Se were developed. Of the three fields, concentrations of soluble Se and salinity were highest in soils from the field drained for 1.5 yr and lowest in the field drained for 6 yr. The field drained for 1.5 yr also had the highest concentration of total Se in soil; a median of 1.2 microgram/gm. Of the total concentration of Se in soil from all three fields, the proportion of adsorbed Se and soluble Se ranged from 1 to 11% and < 1 to 63%, respectively. Most of the variance in soluble Se is explained by salinity ( r sq > 0.68) in saturation extracts of soils sampled from below the water table, reflecting evaporative concentration of Se and salinity. In contrast, most soluble salts and Se apparently have been leached from the unsaturated soils in the fields drained for 6 and 15 yr; therefore, the correlation was lower between Se and salinity in saturation extracts of those soils (r sq < 0.33). Among soils from all three fields, the ratio of Se to salinity in saturation extracts increased with increasing salinity. (Author 's abstract)

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