Universidade Federal de Lavras, Lavras, MG, 37200-000, Brazil.
Instituto Tecnológico Vale, Belém, PA, 66055-090, Brazil.
Ecotoxicology. 2020 Apr;29(3):305-313. doi: 10.1007/s10646-020-02174-8. Epub 2020 Feb 19.
Lead (Pb) in soils can be transferred to plants, animals, and even humans. The toxicity of Pb is worrisome and therefore environmental quality criteria, established by laws to support the management of contaminated sites, have been developed to prevent its deleterious effects in a wide range of soils, uses, and occupations. In Brazil, the CONAMA Resolution 420/2009 established that Brazilian states may define their prevention values (PV) for metals in soils. However, the established values should be well studied, since a wide variation of sensitivity of species exposed to Pb is reported and several have a high tolerance. We aimed to evaluate Pb toxicity to validate the suitability of the current Brazilian Pb-prevention value. A trial was carried with two plant species (sorghum and soybean) grown in two tropical soils (Typic Hapludox and Rhodic Acrudox), following ISO 11.269-2 protocols (ISO 2012). The tested soils were contaminated with Pb-acetate at the following concentrations: 0, 200, 400, 800, 1200, 1600, 2200, 2800, and 3200 mg kg of dry soil. Differences regarding species sensitivity were observed and sorghum seemed to be less sensitive to Pb concentration in soils. Soil characteristics as higher clay and organic matter content were responsible for decreasing the overall availability of Pb for plants. Using data from this study and from the literature, we constructed a species sensitivity distribution curve and calculated the HC5 (hazardous concentration to 5% of variables evaluated). The HC5 was 132.5 mg kg, which suggests that the PV currently used in Brazil (72 mg kg) is sufficiently protective for Brazilian soils.
土壤中的铅（Pb）可以转移到植物、动物，甚至人类身上。铅的毒性令人担忧，因此，为了防止其在广泛的土壤、用途和职业中产生有害影响，制定了环境质量标准，这些标准由法律支持，以管理污染场地。在巴西，CONAMA 决议 420/2009 规定，巴西各州可以为土壤中的金属制定自己的预防值（PV）。然而，所确定的值应该经过充分研究，因为据报道，暴露于铅的物种的敏感性差异很大，而且许多物种的耐受性很高。我们旨在评估铅的毒性，以验证现行巴西铅预防值的适宜性。根据 ISO 11.269-2 协议（ISO 2012），我们用两种植物（高粱和大豆）在两种热带土壤（典型的弱淋溶土和弱发育铁铝土）中进行了一项试验。受测试的土壤用 Pb-醋酸盐污染，浓度分别为：0、200、400、800、1200、1600、2200、2800 和 3200 mg/kg 干土。观察到物种敏感性的差异，高粱对土壤中铅浓度的敏感性似乎较低。土壤特性，如较高的粘土和有机质含量，负责降低铅对植物的整体有效性。利用这项研究和文献中的数据，我们构建了一个物种敏感性分布曲线，并计算了 HC5（评估变量的 5%受到危害的浓度）。HC5 为 132.5 mg/kg，这表明巴西目前使用的 PV（72 mg/kg）对巴西土壤具有足够的保护作用。
