苎麻对农田土壤中汞、镉的吸收累积特征研究

为了评价非食用性经济植物苎麻对农田土壤中汞、镉的累积修复效果,本研究采集了46个种植于某汞矿区周边的汞、镉复合污染农田土壤的苎麻样品,分析了苎麻及对应土壤样品中汞、镉含量,计算了苎麻对汞、镉的累积系数和转运系数。结果表明:汞在苎麻根、秆、皮和叶中的含量分布为58.02~136.97、60.6~560.45、113.26~3 860.51、446.1~1 686.3μg·kg^-1;镉在苎麻根、秆、皮和叶中的含量分布为10.1~1 527.8、7.17~1 203.63、11.57~1 838.14、77.12~842.41μg·kg^-1。麻皮和麻叶中的汞含量明显高于根部;而镉较均匀分布在苎麻的根部、麻秆、麻皮及麻叶。汞和镉在对应土壤中含量分布为0.381~9.040 mg·kg^-1和0.131~7.814 mg·kg^-1。苎麻地上部对汞的累积系数范围为0.017~4.826,转运系数范围为0.583~22.595,苎麻地上部对镉的累积系数范围为0.011~3.725,转运系数范围为0.055~16.175。麻皮的汞累积系数明显高于根部和麻秆;而苎麻各部位的镉累积、转运系数无明显差别。土壤中的DOC含量上升会导致苎麻麻秆、麻皮中汞含量的下降,土壤pH的下降会促进苎麻的麻秆、麻皮两个部位对镉的吸收累积。

Accumulation and transfer of mercury and cadmium in ramie from agricultural soils

Ramie(Boehmeria nivea L. Gaud)is not only a highly economical and non-edible plant, but also an effective plant for heavy metal remediation. In order to evaluate the remediation efficiency of mercury(Hg)and cadmium(Cd)by ramie, 46 ramie and the corresponding soil samples were gathered from agricultural soils located around a mercury mine near Tongren in Guizhou Province. The amounts of Hg and Cd in ramie and the corresponding soil samples were analyzed. The bioaccumulation factor(BAF)and translocation factor(TF)of Hg and Cd were also calculated. The amount of Hg in the root, stem, skin, and leaves of ramie was in the range of 58.02~136.97, 60.6~560.45, 113.26~3 860.51 μg·kg^-1, and 446.1~1 686.3 μg·kg^-1, respectively. The amount of Cd in the root, stem, skin, and leaves of ramie was in the range of 10.1~1 527.8, 7.17~1 203.63, 11.57~1 838.14 μg·kg^-1, and 77.12~842.41 μg·kg^-1, respectively. The amount of Hg was much higher in ramie skin and leaves than in ramie roots. However, the amount of Cd was evenly distributed in the roots, stem, skin, and leaves of ramie. The BAF and TF of Hg were in the range of 0.017~4.826 and 0.583~22.595, respectively. The BAF and TF of Cd were in the range of 0.011~3.725 and 0.055~16.175, respectively. The BAF of Hg was much higher in ramie leaves than in ramie stem and roots.However, there was no significant difference in the BAF of Cd among the roots, stem, skin, and leaves of ramie. The increase in dissolved organic carbon content in the soil led to the decrease in Hg in the stem and skin of ramie, but the decrease in soil pH promoted the uptake and accumulation of Cd in the stem and skin of ramie.