Phytoremediation of arsenic-contaminated soil and groundwater.

摘要

Pteris vittata was effective in taking up arsenic in the presence of various metals and transporting it to the fronds. Arsenic uptake, bioconcentration factors and transfer factors reduced with increasing metal concentration in the soil. Greater concentrations of metals resulted in greater catalase activity in the plant. Most of the arsenic in the plant was present as arsenite (the reduced form) indicating little impact of the metals on plant arsenic reduction. Fractionation analysis before and after plant arsenic uptake in the control soil with no metals spiked showed that Ca-As was the dominant fraction, with Ca-As > Fe-As > Al-As > WE-As. Actual concentrations of Al-As and Fe-As were significantly (P 0.01) greater in all metal-spiked soils than in the control at 8 weeks. Phosphate rock significantly increased arsenic uptake and reduced lead uptake by P. vittata in a multi-metal-arsenic-polluted soil. Arsenic uptake by the fern was positively correlated with both total and available arsenic in the soil. P. vittata had significantly higher aboveground and total biomass than P. cretica. P. vittata also had higher As uptake than P. cretica except in the golf-course soil. GSH availability was not implicated as a detoxification mechanism for arsenic in these ferns. The ability of P. vittata to accumulate As and tolerate metal toxicity better than P. cretica makes it a better candidate for phytoremediation of arsenic contaminated soils. P. vittata was also more efficient than P. cretica in hydroponic conditions with significantly greater arsenic accumulation and translocation. Arsenic reduction from AsV to AsIII in the fronds of P. vittata did not occur appreciably after I-day exposure. P. vittata accumulated arsenic in the fronds while N. exaltata accumulated it in the roots. Pre-exposure to arsenic increased the ability of P. vittata to accumulate arsenic from solution containing higher arsenic concentration. The nitrate-fed ferns (P. vittata) significantly took up more arsenic than did ferns ( P. vittata) fed with the other nutrients. Adding calcium carbonate resulted in greater reduction of solution arsenic. This is very good for the phytofiltration of arsenic-contaminated water in areas where limestone is present in the rock strata.