污染农田水苋菜等野生植物镉富集能力和修复潜力调查

为了从自然环境中寻求重金属高富集植物资源，调查了江苏省某镉（Cd）污染农田的野生植物分布，成对采样分析了19种植物根区土壤-整株的Cd含量，比较了各植株不同部位（根、茎、叶、花、果）对Cd的积累特征。结果表明：各植物生境土壤Cd含量范围为1.72~16.5 mg·kg^-1，植株地上部Cd含量为1.20~43.2 mg·kg^-1，有11种植物的Cd生物富集系数（BCF_Cd）超过1，8种植物由根向地上部迁移的Cd转运系数（TF_Cd）超过1，且其中6种植物的BCF_Cd和TF_Cd都超过1，具备重金属富集植物的特点。不同植物的各器官BCF_Cd和TF_Cd值也呈现较大差异，根部BCF_Cd最高的是水苋菜（6.50），野胡萝卜最低（0.23）；茎中BCF_Cd和TF_Cd最高的都是水苋菜，分别为18.7和2.87，BCF_Cd野胡萝卜最低（0.20），TF_Cd飞廉最低（0.44）；叶中BCF_Cd翅果菊最高（5.44）、野胡萝卜最低（0.33），TF_Cd商陆最高（3.03）、一年蓬最低（0.84）；花中BCF_Cd最高的是碎米莎草（5.17），一年蓬最低（0.24），TF_Cd最高的是野胡萝卜（1.08），飞廉最低（0.26）；果中BCF_Cd和TF_Cd最高的都是水苋菜（22.6和3.47），最低的都是齿果酸模（2.12和0.56）。整株综合评估比较，水苋菜、碎米莎草、青葙和商陆的地上部Cd富集量较高，分别达到了43.2、28.1、22.7 mg·kg^-1和20.7 mg·kg^-1。基于BCF_Cd和TF_Cd，兼顾各种植物的生物量，水苋菜（首次发现）、齿果酸模、碎米莎草、翅果菊用于Cd污染农田土壤修复的潜力较大，值得进一步深入研究和试验。

Investigation of Cd enrichment capacity and remediation potential of wild plants including Ammannia baccifera L. in Cd-contaminated farmland soil

To find plant resources to highly accumulate heavy metals from the natural environment, this study investigated the distribution of wild plants in cadmium(Cd) -contaminated farmland soil of Jiangsu Province, analyzed Cd concentrations in the rhizospheric soil and aboveground biomass of 19 plants via paired sampling and compared Cd accumulations in five plant organs(roots, stems, leaves, flowers, and fruits). Results showed that the Cd concentrations ranged from 1.72 mg·kg^-1 to 16.5 mg·kg^-1 in the soil and from 1.20 mg·kg^-1 to 43.2 mg·kg^-1 in the aboveground biomass. The bioconcentration factor of Cd(BCF_Cd), a characteristic parameter stably indicating the ability of plants to accumulate heavy metals from soil, exceeded unity for eleven plants, while the root-to-aboveground transport factor of Cd(TF_Cd) exceeded unity for eight plants. Both BCF_Cd and TF_Cd exceeded unity for six plants, showing the characteristics of the heavy metal hyperaccumulators. The BCF_Cd and TF_Cd values showed difference among the five organs of the 19 plants. The highest and lowest BCF_Cd in roots belonged to Ammannia baccifera L. (6.50) and Daucus carota L. (0.23), respectively. In stems, the highest BCF_Cd and TF_Cd belonged to A. baccifera L. (18.7 and 2.87, respectively), whereas the lowest BCF_Cd and TF_Cd belonged to D. carota L. (0.20) and Carduus nutans L. (0.44), respectively. In leaves, the highest BCF_Cd and TF_Cd occurred in Lactuca indica L.(5.44) and Phytolacca acinosa Roxb.(3.03), respectively, whereas the lowest BCF_Cd and TF_Cd occurred in D. carota L.(0.33) and Erigeron annuus(L.) Pers.(0.84), respectively. In flowers, the maximum BCF_Cd and TF_Cd belonged to Cyperus iria L. (5.17) and D. carota L. (1.08), respectively, whereas the minimum BCF_Cd and TF_Cd belonged to E. annuus(L.) Pers. (0.24) and C. nutans L. (0.26), respectively. In fruits, the maximum BCF_Cd and TF_Cd occurred in A. baccifera L.(22.6 and 3.47, respectively), whereas the minimum BCF_Cd and TF_Cd occurred in Rumex dentatus L.(2.12 and 0.56, respectively). The aboveground biomass of A. baccifera L., C. iria L., Celosia argentea L., and P. acinosa Roxb. exhibited the highest Cd accumulations of 43.2, 28.1, 22.7 mg·kg^-1, and 20.7 mg·kg^-1, respectively. Taking into account the biomass, A. baccifera L., R. dentatus L., C. iria L., and L. indica L. show the greatest potential for the phytoremediation of Cd-contaminated farmland soil, which warrants further study.