Effect Of Arsenic Species、HCO₃^-and PH On Arsenic Removal By Pteris Vittata L. And Application Research

Arsenic has been identified as a major toxic contaminant in drinking water inmany countries. It is a known carcinogen and nutagen and taratogenic, and posessignificant health risks to people. In recent year, increasing concerns have been paidfor hyperaccumulating technologies in phytoremediating contaminants fromenvironment. Arsenic concentration, species and bicarbonate concentration on arsenicuptake were investigated to evaluate the feasibility of arsenic removal from higharsenic groundwater using hyperaccumulator Pteris vittata L.Effects of As concentration and As species （As（III） and As（V）） on arsenic uptakeby Pteris vittata L were evaluated. Results showed that showed that Pteris vittata L.tolerated high arsenic concentrations. When arsenic concentration was up to100mg·L^-1, removal efficiency of Pteris vittata L. reached80%. Arsenic uptake by Pterisvittata L. was higher in As（III） treatments than that in As（V） treatments. Although onlyinorganic arsenic（III） and arsenic（V） were observed in the plant, contents of As speciesin plants were in association with those in solution. The ratio of As（V） to total As inplants of As（V） treatments was higher than that of As（III） treatments.High arsenic groundwater generally contained high concentration of HCO₃^-withhigh pH. Three levels of HCO₃^-（0.5、2.0、20mmol）,pH values7.2, and pH values （7.2、7.8、8.2） in pH treatments, with As （III） or As （V） concentration of5mg L^-1weredesigined to investigate effects of both HCO₃^-and pH on arsenic uptake by Pterisvittata L. Results showed that high concentrations of HCO₃^-(20mmol L^-1) and pHinhibited the growth of the plant, and showed significant inhibition of arsenic uptake.Arsenic content and transfer coefficient decreased with increasing HCO₃^-concentration in HCO₃^-treatment. In comparison with As （V） treatment, transfercoefficient was lower in As （III） treatment. In pH treatment, transfer coefficient wereno apparent trends in terms of pH variation in both As （V） and As （III） treatments.Pteris vittata L-natural mineral.ecological beds were established to investigate effects of the presence of plant, flow direction, arsenic species, coexisting anions, flowrate on arsenic removal by the ecological beds. Results show that the natural mineralsplayed the role in arsenic removal in the early stage and p. vittata played the role inarsenic removal from water in the later stage. When the number of Pteris vittata L. was20, remove arsenic was better. The influent flow rate of5mL/min was superior to theinfluent flow rate of10mL/min. Arsenic removal was higher in arsenic-spikeddeionized water than arsenic-spiked tap water. Besides, arsenic removal from As（III）treatment was greater than from As（V）.