纳米Fe_(3)O_(4)覆盖对沉积物-水界面砷释放的影响

Effect of nFe_(3)O_(4) capping on arsenic release at sediment-water interface

为揭示纳米四氧化三铁(nFe_(3)O_(4))覆盖对沉积物溶解态砷(As)和有效态As的钝化效果,在开展室内培养试验的基础上,利用微界面分析技术、高分辨率平衡式间隙水采集技术(HR-peeper)和薄膜扩散梯度技术(DGT),探究nFe_(3)O_(4)覆盖下沉积物氧化还原环境、铁锰含量等因素对As的作用机制.结果表明:在nFe_(3)O_(4)覆盖下沉积物pH值较对照组逐渐增大,Eh先减小后增大;nFe_(3)O_(4)可以有效去除沉积物溶解态As,最大有效去除率为22%;nFe_(3)O_(4)覆盖使得有效态As的平均值降低了2.30μg/L;溶解态As与溶解态Fe(Ⅱ)、溶解态As与溶解态Mn、有效态As与有效态Fe(Ⅱ)、有效态As与有效态Mn均存在显著正相关关系(P<0.001);nFe_(3)O_(4)的覆盖可以促进铁铝低结晶状无定形水合氧化态As含量的增加.

In order to reveal the passivation effect of nano-iron tetroxide(nFe_(3)O_(4))covering on soluble arsenic(As)and labile As in sediments,on the basis of laboratory culture experiments,micro-interface analysis technology,high-resolution equilibrium gap Water harvesting technology(HR-peeper)and Diffusive Gradients in Thin-films technology(DGT)were used to explore the mechanism of action of As in the redox environment,iron and manganese content of sediments covered by nFe_(3)O_(4).The results showed that the pH value of the sediment under the coverage of nFe_(3)O_(4) gradually increased compared with the control group,and the Eh first decreased and then increased;nFe_(3)O_(4) could effectively remove dissolved As from sediments,the maximum effective removal rate was 22%;the average value of available As was reduced by 2.30μg/L by the coverage of nFe_(3)O_(4);There was a significant positive correlation between solube As,solube Fe(Ⅱ)and solube Mn(P<0.001).Similarly,there was also a significant positive correlation between labile As,labile Fe(Ⅱ)and labile Mn.(P<0.001);the coverage of nFe_(3)O_(4) could promote the increase of the content of amorphous Fe and Al oxides bound.