铅污染废水中不同湿地植物对铅积累及分配的差异

Differences among Wetland Plants Species in Lead Accumulation and Distribution from Lead-Polluted Wastewater in Constructed Wetlands

摘要: 通过建造人工湿地并设置不同水平的铅污染废水(1.5 mg/L及3.0 mg/L)，研究了十种湿地植物对铅吸收积累及分配的差异。结果表明，供试十种湿地植物间的铅积累能力存在很大差异。不同植物种类间地上部、地下部、全株铅积累量的最大差异(积累量最大植物与积累量最小植物的比值)分别达到9.3~9.7倍、10.5~12.3倍、8.6~9.2倍。分析表明，1.5 mg/L铅污染废水处理与3.0 mg/L铅污染废水处理之间，这些铅积累量的相关性都很强，达到极显著水平(P < 0.01)；而且，地上部与地下部之间铅积累量的相关性也很好，达到显著或极显著水平(P < 0.05 or 0.01)。该结果说明，湿地植物的铅积累能力在不同铅污染水平下保持一致。但十种湿地植物间铅分配的差异相对较小，铅积累量在地上部及地下部分配比例的最大差异分别只有1.5倍左右及3倍多一点。因此，通过植物的铅积累量来筛选用于处理铅污染废水的湿地植物种类比较适宜，而湿地植物地上部铅积累量比地下部更有意义，因为地上部分易于收集处理。根据本研究结果，综合考虑植物地上部及全株铅积累量，有2种植物的铅积累能力明显突出，即茭笋(Zizania latifolia)及空心莲子草(Alternanthera philoxeroides)。在利用人工湿地工程技术处理铅污染废水时，这2种湿地植物有较好的应用前景。

Abstract: The differences among ten wetland plant species in lead (Pb) quantity accumulation and distribu-tion were studied under moderate (1.5 mg/L) and heavy (3.0 mg/L) water Pb stress and in con-structed wetlands. The results showed that the differences among the wetland plant species were large in Pb accumulations in aboveground parts, underground parts and whole plants. The biggest differences were 9.3~9.7 times for Pb accumulation in aboveground parts, 10.5~12.3 times for Pb accumulation in underground parts, and 8.6~9.2 times for Pb accumulation in whole plants. Be-tween 1.5 mg/L of lead-contaminated wastewater treatment and 3.0 mg/L of lead-contaminated wastewater treatment, the correlation of these lead accumulations was very strong and reached an extremely significant level (P < 0.01). The correlations between aboveground parts and under-ground parts in Pb accumulation were also positive and significant (P < 0.05 or 0.01). The results indicate that the abilities of wetland plants in Pb uptake and accumulation remain consistent under different water Pb levels. The wetland plant species with higher Pb accumulations in aboveground parts may accumulate more Pb in underground parts also. But the differences among the wetland plant species in Pb distribution proportions in aboveground parts and underground parts were relatively small. The biggest differences were about 1.5 times for Pb distribution proportions in aboveground parts, and more than 3 times for Pb distribution proportions in underground parts. Therefore, it is better to select suitable wetland plants for the treatment of Pb-polluted wastewater according to their Pb accumulations. Furthermore, the Pb accumulations in aboveground parts are more meaningful, because aboveground parts can be harvested and removed from wetland easily. From the view of comprehensive consideration on the Pb quantity accumulations in aboveground parts and in whole plants, the plant species Zizania latifolia and Alternanthera philoxeroides are outstanding. They are suitable wetland plants to be used in the treatment of Pb-polluted wastewater with constructed wetland.