Survey of the total arsenic content in soils in louisiana

Arsenic (As) is a widely distributed soil contaminant because of past use of As‐containing pesticides. The total As content of representative soils used for agriculture in the major soil areas of Louisiana was determined. The As content of > 450 samples ranged from near zero to 73 mg/kg with a mean of 23.2 mg/kg. Generally, alluvial soils of the Red and Mississippi Rivers Valleys had the highest As contents, while the Ouachita River alluvial soils had the lowest As contents. In general, As levels increased or remained about the same with increasing profile depths. Total As was significantly related to soil texture; soils with higher clay content having higher As contents. Arsenic level was weakly related to organic matter and As level was weakly inversely related to soil pH. Past widespread use of As‐containing pesticides did not appear to have substantially increased the As content of agricultural soils in Louisiana.