Gansu Key Laboratory for Environmental Pollution Prediction and Control, College of Earth and Environmental Sciences, Lanzhou University, Lanzhou, 730000, China.
Key Laboratory of Western China's Environmental Systems (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou, 730000, China.
Environ Sci Pollut Res Int. 2018 Mar;25(8):7418-7432. doi: 10.1007/s11356-017-0994-y. Epub 2017 Dec 26.
Municipal sludge compost (MSC) is commonly used as fertilizer or an amendment in barren soils. However, MSC-borne Cd is of great concern in food safety because of its toxicity. Loess subsoil (LS) is barren and lacks nutrients, but it has a strong ability to absorb and stabilize heavy metals. Hence, LS may be amended with MSC and may reduce the bioavailability of Cd. To simulate the dose effect of the accumulated MSC-borne Cd in amended LS, pot experiments were conducted to study the bioavailability of Cd and other mineral nutrition elements in broad bean (Vicia faba L.) under Cd stress. Plant height and dry biomass remarkably increased as the physicochemical properties of LS were significantly improved; however, they were not significantly influenced by the added Cd. The Cd in the plants grown in MSC amended-LS (P2) mainly accumulated in roots (32.12 mg kg) and then in stems and leaves (6.00 mg kg). Less Cd (0.74 mg kg) accumulated in the edible parts, where the Cd concentration was 53% lower than that in the edible parts of plants grown in LS (P1). The decreased Cd concentrations in the P2 beans may be due to the biomass dilution effect. Notably, the Cd concentrations in the beans exceeded the national safety limit value (0.2 mg kg) when the Cd treatment levels exceeded 2 mg kg in LS and 6 mg kg in amended LS. The MgCl extraction procedures can be used to assess Cd bioavailability in amended soil-plant systems. The potential antagonism of Zn and Cu against Cd toxicity in the soil-plant system may explain why this plant can tolerate higher Cd concentrations after MSC application.
城市污泥堆肥（MSC）通常用作贫瘠土壤的肥料或改良剂。然而，由于其毒性，MSC 携带的 Cd 引起了人们对食品安全的极大关注。黄土底土（LS）贫瘠且缺乏养分，但它具有很强的吸收和稳定重金属的能力。因此，LS 可以用 MSC 进行改良，从而降低 Cd 的生物有效性。为了模拟累积 MSC 携带的 Cd 在改良 LS 中的剂量效应，进行了盆栽实验，以研究 Cd 胁迫下蚕豆（Vicia faba L.）中 Cd 及其他矿物质营养元素的生物有效性。随着 LS 物理化学性质的显著改善，植株高度和干生物量显著增加；然而，Cd 的添加并没有显著影响它们。在 MSC 改良 LS 中生长的植物（P2）中的 Cd 主要积累在根部（32.12mgkg），然后在茎和叶中积累（6.00mgkg）。在可食用部分积累的 Cd 较少（0.74mgkg），其 Cd 浓度比在 LS（P1）中生长的植物的可食用部分低 53%。P2 豆中 Cd 浓度降低可能是由于生物量稀释效应。值得注意的是，当 LS 中 Cd 处理水平超过 2mgkg 或改良 LS 中 Cd 处理水平超过 6mgkg 时，豆中的 Cd 浓度超过了国家安全限量值（0.2mgkg）。MgCl 提取程序可用于评估改良土壤-植物系统中 Cd 的生物有效性。土壤-植物系统中 Zn 和 Cu 对 Cd 毒性的潜在拮抗作用可能解释了为什么这种植物在施用 MSC 后能耐受更高的 Cd 浓度。
