| Ferrous（Fe） plays an important role in the biogeochemical cycle of arsenic（As）. In the present research, the uptake of different As forms as affected by Fe3+ was investigate in three aquatic plants（Hydrilla verticillata, Pistia stratiotes and Eichhornia crassipes）. These plants were cultured using hydroponics. Chromatography hyphenated atomic fluorescence spectrophotometry was used to determine total arsenic contents and its speciation in the culture solution and plant body. The three plants were exposed to culture solution with different As forms（As（V）, As（Ⅲ） or DMA） and different Fe3+ concentrations（0~2 mg·L-1）. The plant biomass, total As adsorption and absorption were also evaluated. The results showed that As accumulation mainly occurred via biological uptake rather than physicochemical adsorption. Total As contents in P. stratiotes and E. crassipes exposed to As（Ⅲ） and in three plants exposed to As（V） increased with the addition of Fe3+. However, the total As contents in the three plants were not affected by Fe3+ addition at DMA treatment. Results from As speciation analysis in culture solution showed that after 10 days of incubation, As（Ⅲ） was transformed to As（V） at As（Ⅲ） treatment. As（V） concentrations in culture solution of H. verticillata or E. crassipes exposed to As（V） were decreased when high concentration of Fe3+ was added. DMA concentrations in the culture solution of E. crassipes exposed to DMA were also decreased with the addition of Fe3+. Results from As speciation analysis in plant parts（root and shoot） showed that root As（V） and As（Ⅲ） contents in P. stratiotes, and root As（V） contents in E. crassipes increased with the addition of Fe3+ at As（Ⅲ） or As（V） treatment. At As（Ⅲ） treatment, the shoot As（Ⅲ） contents in P. stratiotes, and the shoot As（V） contents in E. crassipes increased with the addition of Fe3+. At As（V） treatment, the shoot As（V） and As（Ⅲ） contents in H. verticillata, and the shoot As（Ⅲ） contents in P. stratiotes and E. crassipes increased with the addition of Fe3+. At DMA treatment, the DMA contents in the roots of E. crassipes increased with the addition of Fe3+. The DMA contents in the shoots of E. crassipes increased with the addition of high concentration of Fe3+（2 mg·L-1）. This work indicated that a suitable concentration of Fe3+ could increase As uptake of aquatic plants and improve the remediation efficiency of As-contaminated water. |
