National Institute of Water and Atmospheric Research, PO Box 11-115, Hamilton, New Zealand.
Sci Total Environ. 2010 Feb 1;408(5):1212-20. doi: 10.1016/j.scitotenv.2009.11.053. Epub 2009 Dec 14.
There is increasing interest in the stabilization of heavy metals in road-derived sediments (RDS), to enable environmentally responsible reuse applications and circumvent the need for costly landfill disposal. To reduce the mobility of heavy metals (i.e. Cu, Pb and Zn) the effectiveness of amendments using phosphate, compost and fly ash addition were investigated using batch leaching experiments. In general, phosphate amendments of RDS were found to be ineffective at stabilizing heavy metals, despite being used successfully in soils. Phosphate amendment resulted in enhanced concentrations of dissolved organic carbon (DOC), which increased the solubilisation of heavy metals via complexation. Amendment with humified organic matter (compost) successfully stabilized Cu and Pb in high DOC leaching RDS with an optimum loading of 15-20% (w/w). Compost, however, was ineffective at stabilizing Zn. Increasing the pH by amending RDS/compost blends with 2.5-15% (w/w) coal fly ash resulted in the stabilization of Zn, Cu and Pb. However, above a pH of approximately 7.5 and 8 enhanced leaching of organic matter resulted in an increase in leached Cu and Pb, respectively. Accordingly, the optimum level of fly ash amendment for the RDS/compost blends was estimated to be ca. 10%. Boosted regression trees analysis (BRT) of the data revealed that DOC accounted for 56% and 65% of the Cu and Pb leaching, respectively, whereas pH only accounted for ca. 18% of Cu and Pb leaching. RDS sample characteristics (i.e. metal concentrations, size fractionation and organic matter content) were more important at reconciling the leaching concentrations of copper Cu (27%) than Pb (16%). The most important parameter explaining Zn leaching was pH. Overall, the choice of a suitable stabilization agent/s depends on the composition of RDS with respect to the amount of organic matter present, and the sorption chemistry of the heavy metal of interest.
人们越来越关注稳定道路衍生沉积物（RDS）中的重金属，以实现环境负责的再利用应用，并避免需要昂贵的垃圾填埋处置。为了降低重金属（即 Cu、Pb 和 Zn）的迁移性，使用批式浸出实验研究了使用磷酸盐、堆肥和粉煤灰添加的改良剂的有效性。一般来说，尽管磷酸盐在土壤中成功使用，但 RDS 的磷酸盐改良剂在稳定重金属方面效果不佳。磷酸盐改良剂导致溶解有机碳（DOC）浓度增加，通过络合作用增加了重金属的溶解。腐殖质有机物质（堆肥）的改良成功地稳定了高 DOC 浸出 RDS 中的 Cu 和 Pb，最佳负载量为 15-20%（w/w）。然而，堆肥在稳定 Zn 方面无效。通过用 2.5-15%（w/w）煤灰对 RDS/堆肥混合物进行 pH 值调节，稳定了 Zn、Cu 和 Pb。然而，在 pH 值约为 7.5 和 8 以上时，由于有机质的浸出增加，导致 Cu 和 Pb 的浸出分别增加。因此，RDS/堆肥混合物中粉煤灰的最佳添加水平估计约为 10%。对数据进行的 Boosted Regression Trees 分析（BRT）表明，DOC 分别占 Cu 和 Pb 浸出量的 56%和 65%，而 pH 值仅占 Cu 和 Pb 浸出量的约 18%。RDS 样品特性（即金属浓度、粒度分级和有机质含量）在协调铜 Cu（27%）的浸出浓度方面比 Pb（16%）更为重要。解释 Zn 浸出的最重要参数是 pH 值。总体而言，合适的稳定剂/剂的选择取决于 RDS 的组成，具体取决于存在的有机物量和感兴趣重金属的吸附化学性质。
