四种草本植物对城市非点源模拟雨水中镉的去除效果研究

Cadmium removal effect of 4 grasses in simulated rainfall experiment

采用盆栽实验,研究人工模拟雨水中镉污染物在四种草本植物中的富集及去除效果。本实验同时设定两种情景,即不同入口浓度和不同土壤介质情况下,分析测定了植物地上部分与地下部分镉含量及镉的去除率。结果表明：四种草本植物对人工模拟雨水中镉均有较好的去除效果,镉的平均去除率在89.76%~96.64%之间。四种草本植物对人工模拟雨水中镉污染物的去除能力为：早熟禾〉高羊茅〉地毯草〉黑麦草。四种草本植物对于不同浓度的人工模拟雨水中镉的去除率也不相同。当人工模拟雨水中镉的浓度为0.2mg/L时去除率较高并且去除效果稳定,当浓度为0.02mg/L时,去除率变化幅度大,去除效果相对低。对于同一种草本植物相同的入口浓度情况下,沙土Ⅰ为最佳土壤介质,具有较好的去除镉的能力。四种草本植物地上部分与地下部分的镉含量比值均小于1。四种草本植物对镉的总累积量最大的是黑麦草,36.46μg,最小的是地毯草,21.95μg。实验结果表明,植物体内累积的镉的含量与植物生物量呈正相关关系。该研究对于植物滞留系统结构优化具有一定的理论指导意义。

In order to select the best herbaceous plant for Cadmium（Cd） removal in a bioretention system,the Cd bioaccumulation and removal efficiency by four grasses in bioretention were explicated through a pot experiment.The conditions of different inflow concentration and different soil media were considered in the pot experiment to analyze the removal efficiency and bioaccumulation concentration of Cd by the four grasses.The results showed that the average removal rate of Cadmium was 89.76%~96.64%.The removal capacity of the four grasses follows the order： Poa annuaFestuca elatAxonopus compressusLolium perenne.When the inflow concentration of cadmium was 0.2mg/L,the removal rate of cadmium by four herbaceous plants was higher and stability.However,when the inflow concentration was 0.02mg/L,the removal efficiency was relatively low and changed much.Under the same plant and inflow concentration,the sand had the best removal capacity for the Cadmium.The cadmium content ratios in shoots and in roots of the four grasses were less than 1.Based on the accumulated content in shoots and roots of four herbaceous plants,the highest accumulated content of Cadmium was in Lolium perenne（36.46μg）,and the lowest was in Axonopus compressus（21.95μg）.The accumulated cadmium content of plants was positively correlated with the plant biomass.