泥炭土改良铅锌矿渣下植物修复效果研究

Plants remediation effects of peat soil on lead-zinc tailings

针对铅锌矿渣物理结构差、毒性高、植物成活率低的问题,研究了湖南郴州资兴铅锌矿渣在泥炭土改良下的植物修复效果。以泡桐Paulownia fortunei、夹竹桃Nerium oleander和苎麻Boehmeria nivea为材料,在不同泥炭土浓度(梯度为:CK:0、A1:10%、A2:20%、A3:30%)改良铅锌渣下进行盆栽实验,测定了植物根、茎、叶生物量,根系构型指标、植物与矿渣铅锌含量、矿渣根际土壤pH值、有机质(OM)。研究结果如下:1)随改良剂浓度的增加,3种植物总生物量增量均呈现改良A3> A2> A1> CK的增长趋势,但各部位生物量增长有差异。2)3种植物总根长、根表面积、根体积和根尖都随改良剂浓度增加而增加显著(P <0.05),但根系构型有差异。3)3种植物体内Pb、Zn含量总体上都呈现侧根>主根>茎>叶的分布规律,其中0 <d <1mm径级区间苎麻细根数量最多,对应苎麻侧根Pb、Zn含量最高。随改良处理浓度增加,矿渣Pb、Zn含量降低显著(P <0.05),种植植物后矿渣Pb、Zn含量降低显著(P <0.05),但不同植物根际Pb、Zn含量的降低有差异,Pb减少量排序泡桐>夹竹桃>苎麻,Zn减少量排序苎麻>泡桐>夹竹桃。4)随着处理浓度增加,土壤有机质(OM)增加显著, pH降低显著(P <0.05),种植植物后OM含量和pH值增加显著(P <0.05),OM含量增加排序:苎麻>泡桐>夹竹桃,pH值增加排序:夹竹桃>泡桐>苎麻。5)从细根生长和土壤性质相关性来看,泡桐细根根长、体积、表面积、苎麻细根表面积都和根际OM相关性显著,泡桐细根体积、表面积、夹竹桃体积及根尖数和根际pH负相关显著,其他相关性强但不显著。6)3种植物Pb、Zn总累积量基本随着改良处理浓度增加而增加,但植物转移量系数有差异,泡桐和苎麻转移量系数总体上随改良处理浓度增加而增加,而夹竹桃转移量最优的处理为10%泥炭土。

In view of the poor physical structure,high toxicity,and low plant survival rate in lead-zinc tailings area,the plants remediation effects of peat soil on lead-zinc tailings were studied in Zixing county,Chenzhou,Hunan.Taking Paulownia fortunei, Nerium oleander and Boehmeria nivea as tested materials,the potted experiments was conducted with the improved lead-zinc slag soil prepared from different peat soil concentrations (gradient:CK:0,A1:10%,A2:20%,A3:30%).And the biomass of plant roots,stems and leaves,the index of root architecture,the content of lead and zinc in plant and slag,the pH value of slag rhizosphere soil and organic matter (OM) were measured in the tested area.The findings are as follows.1) With the increase of the modifier concentration,the total biomass of the three plants increased,the increments showed a trend of A3 > A2 > A1 > CK,however,among the three plants and CK there were differences of biomass growth in different parts.2) The total root length,root surface area,root volume and root tip of the three plants increased significantly with the increase of the modifier concentration (P < 0.05),but the root architectures of the three plants were greatly different.3) The contents of Pb and Zn in the three plants all showed the distribution pattern of lateral root > main root > stem > leaf;In the interval of 0 < d < 1mm plant diameter class,the number of fine roots of B.nivea was the largest,and the contents of Pb and Zn in the lateral roots of B.nivea were the highest;With the increase of treatment concentration,the contents of Pb and Zn in the lead-zinc tailings decreased significantly (P < 0.05),and the contents of Pb and Zn in the plants decreased significantly after planted (P < 0.05);However,there were differences in the contents of Pb and Zn in rhizosphere of different plants,Pb reduction order of three plants was P.fortunei > N.fortunei > B.nivea,and Zn reduction ranked as B.nivea > P.fortunei > N.oleander.4) With the increase of treatment concentration,the soil organic matter (OM) increased significantly and the pH decreased significantly (P < 0.05),the OM content and pH value increased significantly after planted (P < 0.05);The increase of OM contents sequenced as B.nivea > P.fortunei > N.oleanderr,and pH increase ranked as N.oleander > P.fortunei > B.nivea.5) From the correlation between fine root growth and soil properties,the fine root length,volume,surface area of P.fortunei,the fine root surface area of B. nivea were significantly correlated with OM of the two plants;the fine root volume,surface area of P.fortunei,volume and root tip number of N.oleanderr were negatively correlated with rhizosphere pH,while other correlations were strong but not significant.6) The total accumulation of Pb and Zn in the three plants increased with the increase of treatment concentration,but there were differences in plant transfer amount coefficients,and the transfer amount coefficients of P.fortunei and B.nivea generally increased with the increase of treatment concentration,but the best treatment of N.oleander was the modifier concentration of 10% peat soil.