Arsenic Uptake in the Hyperaccumulating Fern Pteris Vittata from Soils Contaminated with Pyrite Cinders.

Pyrite cinders, produced when pyrite (FeS2) ore is roasted to make sulfuric acid, are found near chemical, fertilizer, and other industrial facilities worldwide. With elevated metal(loid) impurities, including arsenic (As) and lead (Pb), coupled with low pH, cinders contaminate soil and groundwater. Plant-based technologies offer sustainable alternatives to conventional excavation-based soil remediation methods. Arsenic phytoextraction using the hyperaccumulating fern Pteris vittata is an emerging technology to remediate soils with shallow As contamination with minimal site disturbance. While P. vittata tolerates As through hyperaccumulation, it is not well understood whether and how the fern tolerates elevated metals and how well P. vittata can remove As from acidic, high Fe soils where As availability is low. Remediation rates, which remain slow with P. vittata generally, could be further reduced in the presence of metals. This study will determine the effects of soil fertilization on As phytoextraction with P. vittata under field conditions in the presence of As, Pb, Cu, and Fe, to optimize remediation efficiency. The study soil contains pyrite cinders (As 80 mg/kg, Pb 140 mg/kg, Cu 520 mg/kg, Fe 5%). The soil was tilled, homogenized and limed before plots received 1 of 5 treatments (compost (15% by volume), inorganic N (50 kg N/ha), inorganic P (either 85 kg P/ha or 624 kg P/ha), or inoculation with mycorrhizal fungi ( Funneliformis mosseae)), with no-treatment controls established for comparison. We characterized the chemical form of As and Fe in unremediated soil to offer insights into As phytoavailability. We combined As, Pb, Cu, and Fe uptake in ferns over 10 months, with porewater and surface soil As, Pb, Cu, and Fe contents, to determine if treatments accelerate remediation. Preliminary results suggest that although As is low in bulk soil porewater, treated ferns effectively hyperaccumulate As, with fungi inoculation particularly promoting As removal.