Department of Geosciences and Natural Resource Management, Faculty of Science, University of Copenhagen, Rolighedsvej 23, 1958, Frederiksberg C, Denmark,
Environ Monit Assess. 2013 Nov;185(11):9531-48. doi: 10.1007/s10661-013-3271-7. Epub 2013 Jun 1.
Large quantities of untreated industrial and domestic wastewater are discharged from the city of Hanoi into urban rivers. Sediment samples from three sites in the To Lich River in Hanoi were assessed with respect to the concentrations and potential mobility of cadmium (Cd), nickel (Ni) and lead (Pb). Due to very high Cd concentrations up to 700 mg kg(-1) at one site, the sediment was considered highly unsuitable for any types of land use if dredged and disposed of on land. Chemical sequential extractions of wet and anoxic sediment samples showed that Cd and Pb were largely associated with the redox-sensitive fractions and could thus be mobilised following measures such as resuspension or dredging. To assess the potential mobilisation of heavy metals from the anoxic sediment due to oxidation, the samples were exposed to different oxidants (i.e. atmospheric air and hydrogen peroxide) and afterwards submitted to a leaching test. These experiments showed that although oxidation may increase the equilibrium pore water concentrations of heavy metals in the sediments, other sediment mineral fractions seem to effectively immobilise heavy metals potentially released from the oxidisable fraction.
大量未经处理的工业和生活污水从河内市排入城市河流。对河内市托利克河三个地点的沉积物样本进行了评估，以确定镉（Cd）、镍（Ni）和铅（Pb）的浓度和潜在迁移性。由于一个地点的 Cd 浓度高达 700mg/kg，因此如果疏浚并在陆地上处置，这些沉积物不适用于任何类型的土地利用。湿态和缺氧沉积物样本的化学连续提取表明，Cd 和 Pb 主要与氧化还原敏感分数有关，因此在进行例如再悬浮或疏浚等措施后可能会发生迁移。为了评估由于氧化作用导致缺氧沉积物中重金属的潜在迁移性，将样品暴露于不同的氧化剂（即大气空气和过氧化氢），然后进行浸出试验。这些实验表明，尽管氧化可能会增加沉积物中重金属的平衡孔隙水浓度，但其他沉积物矿物分数似乎有效地固定了可能从可氧化分数释放的重金属。
