Sparingly-Soluble Phosphate Rock induced Significant Plant Growth and Arsenic Uptake by Pteris vittata from Three Contaminated Soils

摘要

We evaluated the ability of As-hyperaccumulatorrnPteris vittata (PV) to remove As from As-contaminated soilsrnover five harvests in 2.5 years in raised beds (162 kg soil/bed).rnWe tested the hypothesis that a P-limiring environment wouldrnenhance PV growth and As uptake owing its unique ability tornuptake P under As-rich environment. in Dec. 2009, PV wasrntransplanted to three As-contaminated soils (pH of 5.5-7.2)rncontaining 25-129 mg kg~(-1) As, which was amended withrnsparingly-soluble phosphate rock (PR-soil) or soluble P fertilizerrn(P-soil). During the 2.5-year, PV obtained sufficient P (1882 vsrn2225 mg kg~(-1)) from PR-soils, with increased root biomassrn(33%) and root exudation (53%) compared to P-soils. Inrnaddition, its frond biomass increased by 20% consecutively with each harvest (six month interval) from 18 to 36 g plant~(-1). itsrnfrond biomass in PR-soils (52.2 g plant~(-1) year~(-1) or ～12 mt ha~(-1) year~(-1)) averaged 39% more than that in P-soils. To ourrnknowledge, this represented the largest PV frond biomass reported, demonstrating the unique ability of PV in using insoluble Prnfrom PR in alkaline soils. in addition to biomass increase, PV from PR-soils had ～1.5 times more As in fronds (2540, 780, andrn920 mg kg~(-1)) than those from P-soils (1740, 570, and 400 mg kg~(-1)), with soils containing 129, 25, and 30 mg kg~(-1) As,rnrespectively. The low available P in PR-soils induced substantial plant growth and As uptake by PV. This translated intornsignificantly more As removal from soil, averaging 48% reduction in PR-soils and 36% in P-soils in 2.5 years. With multiplernharvests and PR amendments, our results showed As removal by PV from contaminated soils was ～7 times faster than publishedrnstudies.