Effect of Soil Texture and Fertilization on Arsenic Phytoextraction with the Hyperaccumulating Fern Pteris vittata Under Field Conditions.

Arsenic (As) contamination is common in urban soils, due to mining activities, smelter fallout, and use of arsenical pesticides and treated wood. Sustainable remediation methods are needed to reduce human exposure to this carcinogen and promote reuse of urban soils. Among in situ methods, phytoextraction is a promising new technology to remediate soils with shallow arsenic contamination, where the hyperaccumulating fern Pteris vittata removes arsenic from soil with minimal site disturbance. However, estimates of remediation times using P. vittata are long, on the order of decades and are based mainly on greenhouse experiments, which likely over-estimate field performance. In addition, most research on arsenic phytoextraction with P. vittata has examined arsenic removal from sandy soils, with little research focusing on arsenic removal from finer-textured soils, where arsenic is less available. The objective of this study is to determine the effects of soil texture and soil fertilization on arsenic extraction by P. vittata, to optimize remediation efficiency and decrease remediation time under complex field conditions. A field study was established 3.5 years ago in an abandoned railroad grade moderately contaminated with arsenic (average 85.5 mg kg-1) with texture varying from sandy loam to silty clay loam. Organic N, inorganic N, organic P, inorganic P, and compost were applied to separate sub-plots while control ferns were grown in untreated soil. Here we link site characteristics, including soil arsenic concentrations, texture, and mineralogy, to 3 years of phytoextraction results, including fern arsenic uptake, nutrition, and remediation rates. Preliminary results indicate higher arsenic uptake in ferns grown in sandy loam soil, compared to in clay loam soil, with the fastest remediation rates achieved in the control and compost-amended ferns.