Department of Soil Science, University of Chittagong, Chittagong, 4331, Bangladesh; State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, No. 130, Meilong Road, Shanghai, 200237, China.
Department of Soil Science, University of Chittagong, Chittagong, 4331, Bangladesh.
Chemosphere. 2021 Sep;279:130570. doi: 10.1016/j.chemosphere.2021.130570. Epub 2021 Apr 14.
Protecting the natural environment and ecological systems from the inorganic pollutants such as lead (Pb) has highlighted the urgent need to develop new and effective approaches for this substance's immobilization in soil. In this study, new, low-cost, and eco-friendly hydroxyapatite (HAp)-like compounds were prepared by reacting oyster shell (Oys) with diammonium phosphate ((NH)HPO) (DAP) and calcium hydroxide (Ca(OH)) at 25-28 °C (OyOHr) and 100 °C (OyOHh). Furthermore, OyOHr and OyOHh were assessed for their effectiveness to immobilize Pb in soil and suppress Pb uptake by Indian spinach (Basella Alba L.). Application of 0.5% OyOHr and OyOHh to soil (by weight) reduced Pb concentration in the shoots by 76.9-78.0% compared to control (CK), to a level that was slightly higher (by 15.5-21.5%) than the recommended food safety level (2 mg kg) suggested by WHO. The changes in Pb fractions revealed that the total contents of oxidizable and residual forms in OyOHr or OyOHh after harvest was >415.0 mg kg, which indicated that >92% of Pb when added to the soil, was immobilized and not able to be taken up by plants. The proposed Pb immobilization mechanism might be the dissolution of OyOHr or OyOHh followed by hydroxypyromorphite (Pb(PO)(OH)) (HP) formation. Due to their facile preparation and eco-friendly and excellent Pb immobilizing characteristics, OyOHr or OyOHh could be readily integrated into current farming systems to mitigate the risk of Pb transferring to plants. However, OyOHr seemed a better immobilizing agent correspond to OyOHh in terms of cost and efficiency.
从无机污染物（如铅（Pb））中保护自然环境和生态系统，凸显了开发新的、有效的方法来固定土壤中这种物质的迫切需要。在这项研究中，通过在 25-28°C（OyOHr）和 100°C（OyOHh）下用牡蛎壳（Oys）与磷酸二铵（(NH)HPO）（DAP）和氢氧化钙（Ca(OH)）反应，制备了新型、低成本、环保的类羟基磷灰石（HAp）化合物（OyOHr 和 OyOHh）。此外，评估了 OyOHr 和 OyOHh 对固定土壤中 Pb 和抑制印度菠菜（Basella Alba L.）对 Pb 吸收的有效性。与对照（CK）相比，将 0.5% OyOHr 和 OyOHh 以重量计应用于土壤，可使地上部分的 Pb 浓度降低 76.9-78.0%，略高于世界卫生组织（WHO）建议的食品安全标准（2mgkg）。Pb 形态的变化表明，收获后 OyOHr 或 OyOHh 中的可氧化和残余形态的总含量>415.0mgkg，这表明添加到土壤中的>92%的 Pb 被固定，不能被植物吸收。提出的 Pb 固定化机制可能是 OyOHr 或 OyOHh 的溶解，随后形成羟磷铅矿（Pb(PO)(OH)）（HP）。由于它们易于制备、环保且具有优异的 Pb 固定特性，OyOHr 或 OyOHh 可以很容易地整合到当前的农业系统中，以降低 Pb 转移到植物的风险。然而，就成本和效率而言，OyOHr 似乎是一种比 OyOHh 更好的固定剂。
