Arsenic Concentrations in Florida Surface Soils
- M. Chen *a,
- L. Q. Mab and
- W. G. Harrisb
Background As concentrations in soils are important for defining whether a soil is polluted. Arsenic concentrations in 441 taxonomically and geographically representative surface soils were determined using EPA Method 3052 (HCl-HNO3-HF digestion). Cumulative distribution plots indicate that As concentrations follow a log-normal distribution and depend on soil type. Sample geometric mean(GM) (the exponential mean of the log-transformed distribution) As concentrations (mg kg−1) generally follow the soil taxonomic order of Histosols (2.35) > Inceptisols (0.98), Mollisols (0.72) ≥ Ultisols (0.51) ≥ Alfisols (0.39), and Entisols (0.36) > Spodosols (0.18). The highest As concentrations were found in soils that occur exclusively or prevalently in wetlands, such as Hemists (3.16–9.44), Saprists (0.15–11.7), Aquents (0.10–50.6), Aquolls (0.03–3.34), and Aquepts (0.03–38.2). Both linear and multiple regressions indicate soil properties (clay, pH, cation-exchange capacity [CEC], organic C, and total Al), especially total Fe and P, are important factors affecting natural background concentrations of As in Florida soils. Arsenic release from bedrock (limestone) and As bioaccumulation by aquatic organisms are possible explanations for relatively high As in those wetland soils. The use of a single regulatory value criterion for As contamination in soil cannot provide an adequate assessment given the natural variation in soil As. Baseline soil-As concentration, which was defined as 95% of the expected range of background As concentrations in different soil categories, is necessary for properly assessing potential As contamination.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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