香根草对水体中镉-扑草净复合污染的吸收去除动态

Dynamics of Absorption and Removal Effects of Vetiveria zizanioides on Cadmium-prometryn Composite Pollution in Water

在工农业生产过程中,由不合理排放的重金属和残留的农药所形成的复合污染在水体及其沉积物中普遍存在。为探讨香根草(Vetiveria zizanioides)对镉-扑草净复合污染水体的修复潜力,采用温室水培模拟试验,研究香根草对水体中Cd(初始质量浓度为0.5 mg·L^(-1))、扑草净(初始质量浓度为1 mg·L^(-1))单一或复合污染物的吸收积累和去除特征。结果表明,随着培养时间的延长,种植香根草组水体Cd^(2+)和扑草净质量浓度均显著低于未种植香根草(对照)组(P<0.05)。经过30 d的培养,单一Cd和扑草净污染处理水体Cd^(2+)和扑草净实际去除率(R 0)分别显著高于Cd-扑草净复合污染处理(P<0.05)。与对照相比,种植香根草使单一扑草净污染和Cd-扑草净复合污染处理水体扑草净半衰期(t_(1/2))和去除99%扑草净所需时间(t_(0.99))均显著缩短(P<0.05)。扑草净半衰期、去除99%扑草净所需时间和扑草净在水体中的降解速率均表现为种植香根草组显著优于未种植香根草组(P<0.05),单一扑草净污染处理显著高于复合污染处理(P<0.05)。培养期间,香根草对水体中Cd^(2+)的吸收主要富集在根系,根系Cd^(2+)含量显著高于茎叶(P<0.05),两者转移系数均小于1。单一扑草净污染处理扑草净在香根草内最大转移系数为1.90,而Cd-扑草净复合污染处理转移系数均小于1。香根草能够同时去除水体中Cd和扑草净,且对单一污染的去除效果优于复合污染,说明香根草能用来修复重金属、农药单一/复合污染水体,为筛选人工湿地植物修复重金属、农药单一/复合污染理想植物提供基础理论依据。

Composite pollution caused by unreasonable discharge of heavy metals and residual pesticides during industrial and agricultural production is prevalent in water and sediments.To explore the remediation potential of vetiver grass(Vetiveria zizanioides)on Cd-prometryn composite polluted water,a greenhouse hydroponic simulation experiment was conducted to investigate the uptake accumulation and removal characteristics of vetiver grass on single/composite pollutants of Cd(initial mass concentration of 0.5 mg·L^(-1))or prometryn(initial mass concentration of 1 mg·L^(-1))in water.The results show that with the increase of incubation time,the concentrations of Cd^(2+)and prometryn in the water of the vetiver grass planted group were significantly lower than those without vetiver grass(P<0.05).After 30 days of incubation,the relative removal rate(R 0)of Cd^(2+)in the water was 55.95%under the single Cd contamination condition,which was significantly higher than the relative removal rate of 47.33%under the Cd-prometryn composite contamination condition(P<0.05).After 30 d of incubation,the water Cd^(2+)and prometryn R 0 were significantly higher in the single Cd or single prometryn contaminated treatment than in the combined Cd-prometryn contaminated treatment(P<0.05).Compared with the control,vetiver grass planting resulted in significantly shorter(P<0.05)half-life(t_(1/2))and time required to remove 99%of prometryn(t_(0.99))in single prometryn contaminated and Cd-prometryn composite contaminated water.Compared with the control,the half-life of prometryn and the time required to remove 99%of prometryn were significantly shorter and the degradation rate of prometryn was significantly higher in the wate of the vetiver grass planted group(P<0.05).Compared with the composite contaminated treatment,the prometryn in the water of the single prometryn contaminated treatment had significantly shorter half-life and shorter 99%removal time and significantly higher degradation rate(P<0.05).During the incubation period,Cd^(2+)uptake by vetiver grass was mainly enriched in the root,and the Cd^(2+)content of the root was significantly higher than that of the stem and leaves(P<0.05),and the transfer coefficients of both were less than 1.The maximum transfer coefficient of prometryn in vetiver grass was 1.90 in the single prometryn treatment,while the transfer coefficients of the Cd-prometryn treatment were less than 1.Vetiver grass is able to remove both Cd and prometryn from water,and the removal effect of single pollution is better than that of composite pollution,indicating that vetiver grass can be used to remediate Cd and pesticide pollution in single/composite pollution water,which provides the theoretical basis for screening the ideal plants for remediation of heavy metal and pesticide single/composite pollution in artificial wetland.