Effect of Soil Water Contents on Arsenic Accumulation in Phytoliths of Pteris multifida and Phragmites australis

The accumulation of metal(loid)s in phytoliths can physically immobilize the toxic materials and reduce toxicity in plant bodies and soil. Spider brake (Pteris multifida) is a well-known As hyperaccumulator that also harbors phytolith. However, As accumulation in phytoliths has not yet been studied with P. multifida. Soil water content is considered the main factor influencing phytolith accumulation. In this study, the As concentration in the phytoliths of P. multifida was compared with that in common reed (Phragmites australis) phytoliths with various soil water content. The range of As concentration in the phytoliths of P. multifida was 414.70–1610.74 mg kg−1, and the range for P. australis phytoliths was 41.67–126.54 mg kg−1. In P. multifida, higher soil water content increased As accumulation in the phytolith but did not affect the phytolith content in the plant. In P. australis, the higher soil water content increased phytolith content in the plant but decreased As concentration in phytoliths. This study suggests that P. multifida has higher As content in phytoliths than P. australis, and this accumulation can be affected by soil water content. The current findings provide how As encapsulated in phytolith and detoxified in different plants and conditions.