Arsenic uptake by Pteris vittata in a subarctic arsenic-contaminated agricultural field in Japan: An 8-year study

In this study, the phytoremediation potential of tropical and subtropical arsenic (As) hyperaccumulating fern Pteris vittata in an As contaminated farmland field near an abandoned goldmine was investigated. The tested field is located in a subarctic area of northeast Japan. This study was aimed at decreasing the risk of As in the soil (water-soluble As) with nurturing the soil and respecting the plant life cycle for the sustainable phytoremediation for 8 years. The field was tilled and planted with new seedlings of the fern every spring and the grown fern was harvested every autumn. The biomass and As concentration in fronds, rhizomes and roots of the fern were analyzed separately after harvesting each year. The biomass of the fronds of P. vittata was significantly affected by the yearly change of the weather condition, but As concentration in fronds was kept at 100-150 mg/kg dry weight. The accumulated As in P. vittata was higher than that of As-hyperaccumulator fern Pteris cretica, the native fern in the field trial area. Harvested biomass of P. vittata per plant was also higher than that of P. cretica. More than 43.5 g As/154 m² (convertible to 2.82 kg of As per hectare) was removed from the farmland field by P. vittata phytoremediation at the end of the 8-year experiment. Because of the short-term plant growth period and soil tilling process, total As in soil did not show significant depletion. However, the water-soluble As in the surface and deeper soil, which is phytoavailable and easily taken in cultivated plants, decreased to 10 μg/L (Japan Environmental Quality Standard for water-soluble As in soil) by the 8-year phytoremediation using P. vittata. These research data elucidate that the tropical and subtropical As hyperaccumulating fern, P. vittata, is applicable for As phytoremediation in the subarctic climate area.