The Soil Arsenic Pollution Status Quo In North Guangdong And Investigation On Uptaked Characteristic Of As(Ⅲ) By Pteris.vittata.L.

Pteris vittata has been identified as a perfect As-hyperaccumulator,and has great applied potential for use in phytoremediation of As-contaminated soil. Therefore comprehending the mechamisms of arsenic hyperaccumulation is great importance in this field.In this research, the method of toluene sequential extraction-iodic titration, which adapt to analysis for high As content in samples,was employed to determine arsenite [As(III)] and arsenate [As(V)] in soil and solution samples. The main results were summarized as follows:1. The investigations of the pollution locate and the check of the soil samples have been done in this paper, it is found that the environment has been polluted heavily by arsenic metallurgy activity with indigenous method in north Guangdong.The highest arsenical content reached 7609.82mg per kilogram soil,and lowest arsenical content reached 3777.02mg per kilogram soil.The chemical value of arsenic in the soil also been analyzed, it is indicates, content of As(V) in more samples are higher than As(III).2. In hydroponic experiments, As( V) were produced while As(III) were absorbed by Pteris vittata. The peak value of arsenate concentrations in soluntion were detected in the range from 6 to 8 hour after supplied arsenite. Afterwards,arsenate concentrations and percentage came down to some extent .It is showed that, The first 6-8h handling in addition arsenite, oxide reaction happened mainly in the presence of Pteris vittata.; afterwards, absorption played dominant role in solution.3. Under some range of As(III) concentrations, absorption of arsenite content varyed with the time going on in the hydroponic experiments. It may be affected by absorption of Pteris vittata. and transporting mechanism. In the range As(III) concentrations from 10 to 1000mg/L, percentage curves of arsenite absorption were mostly increasing linear with increased experiment time in the first 10 hours; Afterwards,the trend were came down. The absorption percentage of treated with 10mg/L arsenite,was reached 97.57% after 24 hour. But when treated with 500mg/L and 1000mg/L arsenite, the arsenic uptake was restrained obviously.4. V_max and K_m are kinetics parameter of enzyme-catalyzed reactions.V_max denote the max uptake velocity of arsenite,and K_m show the affinity that enzyme combining with arsenite in the fornd, K_m and affinity are negative correlativity. The max absorption velocity is emergence when treated with 50mg/L As(III).The value of V_max and K_m were calculated when supplied 10mg/L As(III) by graphics, V_max value is 0.183±0.006mg arsenite per hour per fresh weigh of frond root, K_m value is 2.590±0.080mg/L.5. The research show that,Pteris vittata. uptaked the most arsenite in the absence of phosphorus,when treated with 10mg/L,30mg/L and 50mg/L As(III),respectively. phosphorus inhibited As(III) uptake at all concentrations;but arenite concentrations in soluntion were not affected significantly,when elevating phosphorus concentration from 24mg/L to 60mg/L.Plant uptake more arsenite in acidic environment than in litmusless and alkaline environment. The results suggested that,maximum plant As(III) hyperaccumulation by maintaining minimum soluble P concentrations in medium and adjust pH value(pH≤5.56).The information is important for improving the remediation efficiency of Pteris vittata. and comprehending the mechamisms of arsenic hyperaccumulation.