Arsenic status and distribution in soils at disused cattle dip in South Africa

The status and the distribution of arsenic in soils from a disused cattle dip were determined. Elevated total arsenic levels (1,033-1,369 mg/L) were detected in the soils. Significant difference (p < 0.05) between the values for the soils obtained from the contaminated sites and control site (0.15 mg/L) was observed. The level of total arsenic decreased with increase in depth. The peak total arsenic (1,369 mg/L) was obtained at 0 cm depth, indicating the abundance of arsenic at the surface despite the fact that the dip has been out of use for a long time. The total arsenic recorded for different depths were significantly higher than the trigger value of 40 mg/kg. The distribution of arsenic in the different phases showed that arsenic was mostly bound to the residual fractions (52%) and Fe and Al hydroxides (21%). The distribution of arsenic in the order phases was in the following order: exchangeable (14%), carbonates (10%) and soluble (3%).