Yang Hongjun, Shen Zhemin, Zhu Songhe, Wang Wenhua
School of Environmental Science and engineering, Shanghai Jiao Tong University, China.
Environ Toxicol Chem. 2008 Jan;27(1):38-42. doi: 10.1897/07-089.1.
Properties of vertical distribution of soil near water bodies are vary considerably from those of land and may greatly affect the transportation of heavy metals in wetlands. Vertical distributions of heavy metals (Cr, Cd, Cu, Pb, and Zn) in the soil of aquatic-terrestrial ecotone (ATE) of Lake Taihu, China, and in wetland plant tissues were studied. Generally, concentrations of heavy metals decreased with increasing depth in the top 40-cm cores and then increased slightly with increasing depth. This investigation indicated that concentrations of Cd, Cr, Pb, and Zn exceeded the geochemical background values in the Taihu Lake area. Concentrations of Cd at all depth soil columns exceeded the Environment Quality Standard for Soils of China. Correlation analysis showed that concentrations of Zn, Cr, Cd, and Pb correlated significantly with one another, suggesting that they had the same origin. The concentration of Cu was negatively correlated with root biomass, which may explain the lower concentration of copper in the soil cores. The dominant plants of the wetland were Phragmites australis and Ludwigia prostrata, and heavy metal accumulated primarily in the root tissue. The general order was root > rhizome > stem > leaf, whereas in L. prostrata, leaf was the main tissue for Cr accumulation. Both P. australis and L. prostrata had the highest concentration factor (CF) to Cu, and CF was 20.3 and 15.8, respectively. Aquatic-terrestrial ecotone plants are more effective in controlling Cu pollution than other heavy metals. This will be very significant for ATE reestablishment near Cu-polluted sites.
水体附近土壤的垂直分布特性与陆地土壤差异很大，可能会极大地影响湿地中重金属的迁移。研究了中国太湖水陆交错带（ATE）土壤及湿地植物组织中重金属（铬、镉、铜、铅和锌）的垂直分布。一般来说，在顶部40厘米的土芯中，重金属浓度随深度增加而降低，然后随深度增加略有上升。该调查表明，太湖地区镉、铬、铅和锌的浓度超过了地球化学背景值。所有深度土壤柱中的镉浓度均超过了中国土壤环境质量标准。相关性分析表明，锌、铬、镉和铅的浓度之间存在显著相关性，表明它们来源相同。铜的浓度与根生物量呈负相关，这可能解释了土芯中铜浓度较低的原因。湿地的优势植物为芦苇和矮生柳叶菜，重金属主要积累在根组织中。一般顺序为根＞根茎＞茎＞叶，而在矮生柳叶菜中，叶是铬积累的主要组织。芦苇和矮生柳叶菜对铜的富集系数（CF）均最高，分别为20.3和15.8。水陆交错带植物在控制铜污染方面比其他重金属更有效。这对于铜污染场地附近的水陆交错带重建具有重要意义。
