School of Chemistry and Chemical Engineering, Henan University of Technology, Zhengzhou, Henan 450001, China.
J Hazard Mater. 2013 Nov 15;262:250-5. doi: 10.1016/j.jhazmat.2013.08.058. Epub 2013 Aug 30.
Phosphate amendments in calcareous lead (Pb)-contaminated soils to immobilize Pb may be hindered due to competition of Pb with calcium (Ca) that may inhibit the retention of Pb as a precipitation mechanism. This study explored the retention of Pb in a calcareous soil spiked and aged with 500 mg kg(-1) Pb(2+) and amended with H2PO4(-). In addition, Ca(2+) was added immediately or three days before or after phosphate, after which ryegrass (Lolium perenne) was planted. Diethylene triamine pentaacetic acid (DTPA)-extractable Pb of the soils in which Ca was added immediately after phosphate was lower than those only amended with phosphate or when Ca was added three days before or after phosphate. The addition of Ca immediately after phosphate resulted in the greatest reduction of ammonia acetate-exchangeable Ca concentration, Olsen-P concentration, and carbonate phase Pb. Higher plant biomass yields were observed for the simultaneous P and Ca treatment. The results of the study demonstrate that co-added Ca and P may help reduce Pb availability by forming fresh Ca-P sorbent phases to retain Pb through an adsorption-substitution mechanism, which may play an important role in the sequestration of Pb in calcareous soils with soluble phosphate in addition to the mechanism of the direct precipitation as pyromorphite.
在石灰性铅（Pb）污染土壤中添加磷酸盐来固定 Pb 可能会受到阻碍，因为 Pb 与钙（Ca）的竞争可能会抑制 Pb 作为沉淀机制的保留。本研究探讨了在添加 500mgkg(-1) Pb(2+)并添加 H2PO4(-)的石灰性土壤中 Pb 的保留情况。此外，在添加磷酸盐后立即或三天前或三天后添加 Ca(2+)，然后种植黑麦草（Lolium perenne）。与仅添加磷酸盐或在添加磷酸盐前三天或后三天添加 Ca 的土壤相比，在添加磷酸盐后立即添加 Ca 的土壤中 DTPA 可提取 Pb 较低。在添加磷酸盐后立即添加 Ca 会导致氨乙酸交换态 Ca 浓度、Olsen-P 浓度和碳酸盐相 Pb 的最大降低。同时添加 P 和 Ca 处理可观察到更高的植物生物量产量。研究结果表明，添加 Ca 和 P 可能有助于通过形成新的 Ca-P 吸附剂相来减少 Pb 的有效性，通过吸附-取代机制保留 Pb，这在石灰性土壤中除了直接形成磷铅矿沉淀机制外，可能对可溶性磷酸盐中 Pb 的固定具有重要作用。
