纳塔栎和柳叶栎对铅锌矿区污染土壤的修复潜力分析:田间试验

通过野外调查、采样和实验室分析方法，研究优新景观树种纳塔栎（Quercus nuttallii）和柳叶栎（Quercus phellos）对湖南郴州Pb、Zn矿区复合污染土壤的适应性和修复潜力。试验设计A、B、E区种植1年生纳塔栎，C、D区种植1年生柳叶栎，1年后测量株高、地径、生物量等生长指标，随机采集植物全株及根际土壤，测试植物根际土壤和树木组织中的重金属含量。试验结果：Pb、Zn矿区土壤受到重金属Cd、Pb、Zn和As的复合污染，不同区域的土壤表现出污染异质性，采用单污染指数（Pi）和内梅罗指数（P_N）评价不同地块的污染程度，A区尾矿库（P_N=20.08）和B区（P_N=3.14）为重度复合污染，C区（P_N=2.43）为中度复合污染，D区（P_N=1.55）和E区（P_N=1.07）为轻微污染。纳塔栎和柳叶栎在以上不同污染地块均能正常生长，株高、地径和生物量与复合污染指数（内梅罗指数）及重金属含量呈负相关。其中纳塔栎对Cd的生物富集系数（BCF）在A、B、E区分别为6.27-8.37、3.67-4.38、42.93-52.75，高于C、D区柳叶栎对Cd的生物富集系数1.79-2.15、0.89-1.07。B-E区Zn的转运系数（TF）在1.79-2.28之间，A区Zn的转运系数为0.43。结论：纳塔栎和柳叶栎表现出较强的重金属耐性，对Cd具有较高的生物富集能力，对Zn具有较高的转运能力。其中纳塔栎对重金属积累能力较强，可作为亚热带地区铅锌矿区Cd、Pb、Zn、As复合污染土壤的植被恢复及生态修复候选树种。

The remediation potential of Quercus nuttallii and Quercus phellos to heavy metal polluted soil in lead-zinc mining area: a field test

Through field surveys, sampling and laboratory analysis, we investigated the adaptability and restoration potential of Quercus nuttallii and Quercus phellos grown in a lead and zinc mining area in Linwu county, Chenzhou, Hunan province. After the one-year-old seedlings of Q. nuttallii and Q. phellos were planted in mining contaminated soil for one year, the plant height, stem diameter and biomass of each plant species were recorded, and the metal concentrations in plant tissues and the rhizosphere soil were determined as well. Results showed that the soil was polluted by Cd, Pb, Zn and As with high heterogeneity. Single pollution index and Nemerow index were used to evaluate the pollution degree of different plots. We found that tailing ponds in zone A (P_N=20.08) and zone B (P_N=3.14) were severely polluted, zone C (P_N=2.43) was moderately polluted, while zone D (P_N=1.55) and E (P_N=1.07) were slightly polluted. Q. nuttallii and Q. phellos grew well in the above-contaminated plots. Plant height, stem diameter and biomass were negatively correlated with composite pollution index and heavy metal level. Q. nuttallii had a high bioconcentration factor (BCF) for Cd, the BCF in zones A, B and E were 6.27-8.37, 3.67-4.38 and 42.93-52.75, respectively, which was significantly higher than those of Q. phellos in zones C and D (1.79-2.15, 0.89-1.07). Both Q. nuttallii and Q. phellos had high transport capacity for Zn, with the translocation factor (TF) values of 1.79 and 2.28 in zone B and E, and in zone A with moderate Zn pollution being 0.43. Q. nuttallii and Q. phellos showed stronger heavy metal tolerance, higher bioenrichment ability for Cd, and higher transport capacity for Zn. Q. nuttallii could accumulate more heavy metals and could become an ideal vegetation restoration and ecological restoration tree species for soil contaminated by the Cd, Pb, Zn, As in the mining area in subtropical zone in China.