Critical Perspectives on Soil Geochemical Properties Limiting Arsenic Phytoextraction with Hyperaccumulator Pteris vittata

Abstract

Arsenic is a metalloid widely distributed in the environment and of global concern for human health. In a promising breakthrough for sustainable arsenic soil remediation, a fern, Pteris vittata L., was discovered to take up arsenic from the soil and accumulate it in its fronds at up to ~100 times soil concentrations. Successively harvesting the fronds removes, or phytoextracts, arsenic from the soil with potential environmental and economic benefits including low site disturbance and low cost. The practical use of P. vittata for soil remediation faces challenges largely stemming from the complex nature of the soil. Here, we review soil geochemical processes governing the transport of arsenic from soil to the roots of arsenic-hyperaccumulating ferns. We find that phytoextraction is a soil-dependent process, but that key soil attributes including texture are often not reported. We show that rhizosphere processes play a crucial role in arsenic phytoextraction, and that nutrient management is most successful with ecologically based approaches including sparingly soluble nutrient forms. We conclude that a multi-scale ecological approach is needed to validate P. vittata behavior across controlled and field conditions, and arsenic movement between soil, water, and plant compartments. Our synthesis suggests that phytoextraction as currently practiced is limited to soils with low arsenic concentrations and that P. vittata cultivation is climate-limited to a zone smaller than its range as a wild species.