重金属复合污染下草本植物两两组合水培的富集特性

为了探明草本植物两两组合培养对其重金属富集特性的影响,寻求修复V、Pb、Cd、Cr复合污染的最佳草本植物组合模式,在V、Pb、Cd、Cr 4种重金属〔ρ分别为14.0、0.8、6.0、4.0 mg/L〕共存的水培条件下,研究蒌蒿(Artemisia selengensis turcz)、三叶草(Trifolium repens)、鱼腥草(Houttuynia cordata)和紫花苜蓿(Medicago sativa) 4种草本植物两两组合培养时的重金属富集特性,以及对植物生物量、重金属富集量和转运系数的影响. 结果表明:4种草本植物两两组合培养会在不同程度上影响植物的重金属富集特性,在重金属富集能力方面,蒌蒿、鱼腥草和紫花苜蓿分别与三叶草组合培养时,其地上部分w(Cr)分别比单独培养时提高约157%、303%、639%；两两组合培养时,紫花苜蓿可促进蒌蒿、鱼腥草和三叶草对Pb的吸收. 在重金属转移能力方面,效果最突出的是“三叶草‖紫花苜蓿”组合模式,其中三叶草对V、Pb、Cd、Cr 4种重金属的转运系数分别是单独培养时的1.19、2.52、22.60和1.67倍；对不同组合模式下植物地上部分重金属提取量的分析结果显示,“三叶草‖紫花苜蓿”组合模式对V、Pb、Cd、Cr 4种重金属的提取量均较高,分别为1 555、1 688、473、482 mg/kg,表明该组合模式能够有效缓解地表径流对附近土壤造成的叠加污染. 因此,水培条件下不同草本植物两两组合培养会改变植物的重金属富集特性,并且与植物种类有关. 

Enrichment Characteristics of Various Heavy Metals by Four Herbaceous Plants in Pair Combination under Hydroponic Culture

Vanadium contamination combined with many other heavy-metal ions (e.g.,As,Cd,Cr6+, Cu,etc.) happens frequently in V-ore mining and processing districts in China such as in Hubei, Shanxi and Hunan provinces. High concentrations of V5+in water and soil are toxic to both plants and animals. Moreover, heavy metal combined contamination is more toxic. Numerous reports have indicated that plant coexistence can accumulate more kinds of heavy metals compared to monocultures. Four herbaceous plants (Artemisia selengensis,Trifolium repens,Houttuynia cordata, and Medicago sativa) were mix cropped by pairwise in hydroponic culture system. The aim was to investigate the effects of different pairwise combination patterns on removing combined heavy metals of Cd, Cr, Pb and V and explore the best pairwise coupling pattern. The heavy-metal concentrations were 14.0,0.8,6.0 and 4.0 mg/L for V, Pb, Cd and Cr, respectively. Based on biomass, enrichment contents of heavy metals, and translocation factor, the results indicated that the enrichment ability of each plant could be affected significantly in different pairwise combination patterns. When coexisted with T.repens, the Cd concentration in aerial part of A. selengensis, H. cordata, and M. sativa increased about 157%, 303%, and 639% compared to monoculture, respectively. Meanwhile, the accumulation ability of Pb by A. selengensis, T. repensand H. cordata also increased obviously when coexisting with M. sativa. The transportation ability was most prominent by T. repens, and the translocation factors of V, Pb, Cd, and Cr were 1.19,2.52,2.60, and 1.67 times more than monoculture, respectively. Based on the mean concentration in the aerial part of every metal in different patterns, ‘T. repens‖M. sativa’ proved to be the greatest. The accumulations of V, Pb, Cr and Cd by ‘T. repens‖M. sativa’ were 1555,8, 473,2 mg/kg, respectively. These findings indicated that heavy metal enrichment characteristics of herbaceous plants may be influenced significantly by coexistence with other plants under hydroponic culture, which was closely related with plant species. The research could serve as a certain guide for the repair of compound pollution of heavy metals by plants coexistence.