人工湿地不同植物根系及基质重金属富集特征及其与环境因子相关性

Heavy metal accumulation in roots and substrates of different plants in constructed wetlands and their correlations with environmental factors

为了研究复合垂直潜流人工湿地对池塘养殖水体中重金属的去除效果,通过对水质指标以及重金属的测定,进而分析了不同植物根系及其根系附近基质对重金属富集效果的差异以及不同环境因素与重金属富集速率之间的相关性。结果表明:人工湿地对水体中铅、铜的去除效果分别为77.20%和41.70%,相比于其他类型的湿地,复合垂直潜流人工湿地对铅、铜的去除具有一定优势;砷在湿地中存在释放现象,平均释放率为8.40%。水蓼和再力花根系对铬、砷、铅、铜具有富集作用,梭鱼草仅对铬、砷存在富集作用。水蓼、梭鱼草、再力花根系附近基质均对铬有较好的富集作用,其中梭鱼草对铬的富集速率最大,为0.987 mg/(kg·d)。水蓼根系对铅和铜的富集速率与水温存在显著负相关性,对铬、铜的富集速率与pH存在显著负相关性;梭鱼草根系对铬、砷富集速率与水温存在显著负相关性;再力花根系对铅富集速率与水温、pH存在显著负相关性,对铜的富集速率与水温存在显著负相关性。本研究结果从重金属去除的角度为复合垂直潜流人工湿地的应用以及湿地植物的选择提供一定理论依据和参考。

In order to study the effect of composite vertical subsurface flow constructed wetlands on the removal of heavy metals in pond aquaculture water,the correlation between different plant roots and their substrates near roots on heavy metal enrichment effect,different environmental factors and heavy metal enrichment rate were analyzed by measuring water quality index and heavy metal. The results showed that the removal efficiencies of Pb and Cu in constructed wetlands were 77. 20% and 41. 70%,respectively.Compared with other types of wetlands,the composite vertical subsurface flow constructed wetlands had some advantages for the removal of Pb and Cu; the As was released in wetland with an average release rate of8. 40%. The roots of Polygonum hydropiper and Thalia dealbata Fraser have enrichment effect on Cr,As,Pb and Cu,and the roots of Pontederia cordata L. have only enrichment of Cr and As. The substrates near the roots of Polygonum hydropiper,Pontederia cordata L.,and Thalia dealbata Fraser have a good enrichment effect on chromium,and among them,the maximum rate of the concentration of Pontederia cordata L. to chromium is 0. 987 mg/（kg · d）. The enrichment rate of Pb and Cu in Polygonum hydropiper root was negatively correlated with temperature and the enrichment rate of Cr and Cu was negatively correlated with pH; the enrichment rate of Cr and As in Pontederia cordata L. root was negatively correlated with temperature; the enrichment rate of Pb in Thalia dealbata Fraser root was negatively correlated with temperature and pH,the enrichment rate of Cu was negatively correlated with temperature. The results of this study provide a theoretical basis and reference for the application of composite vertical subsurface flow constructed wetlands and the selection of wetland plants from the perspective of heavy metal removal.