Arsenic Status and Distribution in Soils at Disused Cattle Dip in South Africa

Abstract

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%).

Variability in Heavy Metal Levels in River Water Receiving Effluents in Cape Town, South Africa

“…The high concentrations of arsenic at site 7 may be attributed to defeacating by cattle in the water as the water is used for livestock management in the area. Another possible means of arsenic in this section of the river may be attributed to the use of sodium salt of arsenous acid to treat tick infestations on cattle [20] and waste tyres dump. At sites 11 and 13, the high concentration of arsenic recorded may be attributed to seepage of landfill leachate into the river systems at site 11.…”

Evaluation of Spatial Variability of Soil Arsenic Adjacent to a Disused Cattle-Dip Site, Using Model-Based Geostatistics

“…A significant increase in the northings-trend of phosphate-extractable As at the lowest depth is also evident in the map (i.e., the blue color in proximity of the cattle-dip showing higher As concentration) (Figure d). This could be associated with the continuous deposition and outflow of dip solution in the area adjacent to the cattle-dip that could possibly result in the greater downward flow of As. ,,, …”

“…Estimation of the spatial distribution of As is imperative to precisely quantify its concentration at contaminated sites. , Such information can also assist in designing suitable remediation and management strategies of As-contaminated sites as it can delineate the level and spread of As contamination . Arsenical pesticides were used to control ticks in livestock from the early 1900s to 1955. , This resulted in As contamination of the soil surrounding (now disused) cattle-dip sites in many countries including, Australia, the United States, Republic of South Africa, and New Zealand. ,, The distribution of total As content in soils around disused cattle-dip sites in New South Wales (NSW), Australia, has been found to be high and extremely variable. − Recently, Niazi et al investigated the distribution of total As concentration in the topsoil (0–20 cm) adjacent to a cattle-dip site at the Wollongbar Research Institute in northern NSW, Australia. They reported that soil As concentrations varied over submeter scales, with total As concentration ranging from 313 to 1902 mg kg –1 , which is well above the ecological investigation level (EIL, 20 mg kg –1 ) of total As in the soil in Australia .…”

Soil Contamination with Metals

“…This resulted in As contamination of surrounding soil in cattle-dip sites in many countries, including, Australia, the United States, Republic of South Africa and New Zealand (Okonkwo, 2007;Sarkar et al, 2007). Since the 1960s, there has been a significant reduction in agricultural application of As-based pesticides; however, some arsenical pesticides are still in use such as lead arsenate, copper acetoarsenite (Paris green), Bordeaux blue and organic mercury fumigants (Peryea, 1998).…”