Risk Assessment of Contamination of the Country's Soil and Water Resources with Arsenic

Arsenic is a metalloid that is toxic to plants, animals, microorganisms, and humans. WHO has set the permissible limit of arsenic in drinking water at 10 μg/l and various literatures have reported this limit for the soil to be 20 mg/kg. The concentration of arsenic in water and soil at different parts of Iran (areas with concentrations higher than the permissible limit) have been reported to be 10-840 μg/l and 23.1-1775.2 mg/kg, respectively. The major sources of arsenic contamination in Iran are gold and copper mines (especially Takab and Kerman areas) and Urmia-Dokhtar volcanic formation, which contain various heavy and toxic metals. The most mines of Iran are located on this formation and the use of old mining techniques and equipment has increased the severity of the contamination. In addition, the use of pesticides, insecticides, and other agricultural inputs has led the entry of arsenic into these resources. Using the genetic diversity of plants (plants resistant to arsenic), remediation of arsenic contaminated environments and increasing the concentrations of plant nutrients such as iron, manganese, phosphate, sulfur, and silicon in the soil or growth medium, can greatly reduce the concentration of arsenic in plant tissues, especially in rice. The use of modern equipment in mining can be useful to reduce environmental pollution. Contamination of surface and subsurface water to arsenic in 13 provinces of the country indicates the serious threat of arsenic to people's health and this makes decontamination of water in these areas compulsory.