铬在水平潜流和垂直流人工湿地中的形态转化和迁移

本研究以薏苡为湿地植物，构建了小型垂直流人工湿地（VC）和水平潜流人工湿地（HC），研究了不同水分管理对处理Cr⁶⁺废水时铬的迁移转化的影响。结果表明： Cr⁶⁺处理下，两种湿地的薏苡生长均受到了抑制，水平潜流人工湿地薏苡生长受抑制程度低于垂直流人工湿地。水平潜流人工湿地铬含量较高，而垂直流人工湿地易吸收的可交换态和碳酸盐提取态铬含量较高。基质的pH和Eh均随Cr⁶⁺浓度的增加而呈现减小趋势。垂直流人工湿地pH及Eh值均大于水平潜流人工湿地。与潜流人工湿地相关的酶活性相比，垂直流人工湿地可以增加基质中蔗糖酶活性，但Cr⁶⁺处理下脲酶活性却低于水平潜流人工湿地。高通量分析表明，不同处理下的两种人工湿地基质微生物群落存在显著差异，水平潜流人工湿地微生物更有利于将铬转化为难以利用的铬形态。水平潜流人工湿地对废水中的Cr⁶⁺有更好的去除能力。研究表明，水平潜流人工湿地有利于促进Cr⁶⁺转化为难以利用的铬形态，提高了人工湿地对污水中Cr⁶⁺的去除能力。

Morphological transformation and migration of chromium in horizontal subsurface flow and vertical flow constructed wetlands

In this study, a small vertical flow-constructed wetland(VC) and a horizontal subsurface flow-constructed wetland(HC)were constructed with Coix lacryma-jobi L. as a wetland plant. The effects of different water management techniques on the migration and transformation of chromium in Cr⁶⁺ wastewater were investigated. The results revealed that:Under Cr⁶⁺ treatment, the growth of Coix lacryma-jobi L. in the two wetlands was inhibited, and the growth of Coix lacryma-jobi L. in horizontal subsurface flow-constructed wetland was less inhibited than that in vertical flow-constructed wetland. The content of chromium in the horizontal subsurface flowconstructed wetland was higher, whereas the content of exchangeable and carbonate-extractable chromium in the vertical flow-constructed wetland was higher. The pH value and Eh of the substrate decreased as Cr⁶⁺ concentration increased. The pH and Eh values of vertical flowconstructed wetlands were higher than those of horizontal subsurface flow-constructed wetlands. Compared with the enzyme activities related to the subsurface flow-constructed wetland, vertical flow-constructed wetland could increase the sucrase activity in the substrate; however, the urease activity under Cr⁶⁺ treatment was lower than that in the horizontal subsurface flow-constructed wetland. Highthroughput analysis demonstrated significant differences in microbial communities between the two constructed wetlands under different treatments. Horizontal subsurface flow-constructed wetland microorganisms were more conducive to converting chromium into difficult-touse chromium forms. Horizontal subsurface flow-constructed wetland is more effective at removing Cr⁶⁺ from wastewater. The results demonstrated that the horizontal subsurface flow-constructed wetland was beneficial in promoting Cr⁶⁺ transformation into chromium form, which was challenging to use, and improved the removal ability of Cr⁶⁺ in wastewater.