添加互花米草碎屑的人工湿地对阿特拉津和重金属的净化效果

Purification Effect of Constructed Wetland with Spartina alterniflora Litter on Atrazine and Heavy Metals

为了明确互花米草(Spartina alterniflora)碎屑能否强化人工湿地对阿特拉津和重金属复合污染的净化作用,搭建了人工湿地装置,分析互花米草碎屑埋入土壤和置于土壤表面条件下阿特拉津的去除效果和重金属形态变化,并分析了土壤理化性质的变化,探究添加互花米草碎屑的人工湿地对去除阿特拉津和重金属的影响因素。研究结果表明,在阿特拉津单一污染条件下,添加互花米草碎屑后,阿特拉津去除率从65.7%提升到88.7%,而在阿特拉津和重金属复合污染条件下,去除率从64.6%提升到89.6%;从阿特拉津降解半衰期看,埋入土壤的处理组半衰期为54.2 d,置于土壤表面的半衰期为60.8 d,埋入土壤的处理更能强化人工湿地对阿特拉津的净化能力;不论埋入土壤还是置于土壤表面的处理,都能够促进人工湿地土壤中重金属Cu从离子可交换态向可氧化态转化,可氧化态的占比增大10%;在重金属单一污染条件下,可氧化态Cu质量比在14 mg/kg左右,在重金属和阿特拉津复合污染条件下,可氧化态Cu质量比为16 mg/kg,在复合污染条件下Cu转化为稳定态的量更多,而对重金属Fe和Pb的效果不明显;添加互花米草碎屑有利于降低人工湿地的含盐量,维持人工湿地pH在6~7之间,能够促进阿特拉津降解及Cu向稳定态转化。

In order to investigate the impact of Spartina alterniflora litter on the purification efficiency of a constructed wetland in treating combined pollution of atrazine and heavy metals,a simulated wetland device was constructed.The study analyzed the removal efficiency of atrazine and the distribution of heavy metals when Spartina alterniflora litter was either buried in the soil or placed on the soil surface.The research also examined changes in soil physical and chemical properties and explored the factors influencing the removal of atrazine and heavy metals in the wetland with Spartina alterniflora litter.Results indicated that the removal rate of atrazine increased from 65.7%to 88.7%under single atrazine pollution and from 64.6%to 89.6%under combined pollution of atrazine and heavy metals.The degradation half-life of atrazine was 54.2 days for the buried treatment group and 60.8 days for the surface treatment group,suggesting that burying the litter in soil enhanced the wetland's atrazine removal capacity.Furthermore,the conversion of Cu from an exchangeable to an oxidizable state in the wetland soil was promoted by both burial and surface litter treatment,with about 10%increase in oxidizable Cu.The concentration of oxidizable Cu was approximately14 mg/kg under single heavy metal pollution and 16 mg/kg under combined pollution,indicating more Cu transformed into a stable state under combined pollution.However,the changes of heavy metals Fe and Pb were less pronounced.Addition of Spartina alterniflora litter reduced salt content in the wetland soil,maintained a pH level between 6 and 7,and facilitated atrazine degradation and Cu conversion to a stable state.