Hossain M A, Furumai H, Nakajima F, Aryal R K
Department of Urban Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
Water Sci Technol. 2007;56(11):81-9. doi: 10.2166/wst.2007.746.
Heavy metals speciation analysis was carried out on sediment samples accumulated within soakaways in an old stormwater infiltration facility in Tokyo, Japan and on a soil core sample collected near the facility. Heavy metals content in soakaways sediments were much elevated compared to nearby surface soil with the content for Zn, Pb and Cd reaching about 5 to 10 times the content in surface soil. Speciation results revealed that significant amount of the accumulated heavy metals were present in potential mobile fractions, posing threat of release to underlying soil with changing environmental conditions. Detail analyses of soil characteristics indicated significant heterogeneity with depth, especially between the surface soil and underlying soil at site. Decrease in potential adsorption sites with depth was observed in case of underlying soil. Reduced adsorption capacity for heavy metals was evidenced for underlying soil when compared with surface soil. Furthermore, less capability of the soil organic matter to bind heavy metals was evidenced through speciation analyses, which raises concern over the long-term pollution retention potential of the underlying soil receiving infiltrated runoff.
对日本东京一个旧雨水渗透设施渗水井内积累的沉积物样本以及设施附近采集的土壤岩芯样本进行了重金属形态分析。渗水井沉积物中的重金属含量比附近表层土壤高得多，锌、铅和镉的含量达到表层土壤含量的约5至10倍。形态分析结果表明，大量积累的重金属以潜在可移动形态存在，随着环境条件变化，对下层土壤有释放威胁。土壤特性的详细分析表明，随深度存在显著异质性，尤其是现场表层土壤和下层土壤之间。下层土壤中观察到潜在吸附位点随深度减少。与表层土壤相比，下层土壤对重金属的吸附能力降低得到证实。此外，通过形态分析证明土壤有机质结合重金属的能力较弱，这引发了对接收渗透径流的下层土壤长期污染保留潜力的担忧。
