Arsenic, lead, and other trace elements in soils contaminated with pesticide residues at the Hanford site (USA).

The primary purpose of this study was to characterize arsenic (As) and lead (Pb) concentrations in former orchard soils contaminated with lead arsenate pesticides at the Hanford site in Washington state (USA). Surface samples (n = 31) were collected from former orchard soils (in cultivation during the pre-Hanford period) at five locations at the 100 Areas and at one location at the Old Hanford Townsite (OHT). Another set of samples (n = 17) was collected over a soil depth interval of 10-50 cm at the four locations with the highest As and Pb surface concentrations. All samples were analyzed for 22 trace elements (including As and Pb) with inductively coupled plasma-atomic emission spectrometry (ICP-AES). The mean, standard deviation, and range for As in the surface soils were 30, 61, and 2.9-270 mg/kg dry wt, respectively. The corresponding statistics for Pb were 220, 460, and 6.5-1900 mg/kg dry wt, respectively. As and Pb concentrations in the surface soils were positively and significantly correlated (r = 0.91, Bonferroni p < 0.05). Descriptive statistics and bivariate correlations were also computed for other trace elements. As and Pb mean concentrations in the surface soils each differed significantly (p < 0.05) among Hanford locations, with the highest concentrations at the 100-H and 100-F Areas. Although both As and Pb mean concentrations decreased with soil depth, regression and correlation coefficients only, for Pb significantly differed from zero (b = -0.0372, r = -0.805, Bonferroni p < 0.05). Compared with data in the literature As and Pb concentrations found in this study exceeded background levels but were typical of orchard soils. Furthermore, mean As and Pb soil concentrations were in the range of various toxicological benchmarks derived for protection of human and ecological receptors.