Lima Jacqueline Zanin, Rodrigues Valéria Guimarães Silvestre
Department of Geotechnical Engineering, São Carlos School of Engineering, University of São Paulo, São Carlos, SP, 13560-970, Brazil.
Department of Geotechnical Engineering, São Carlos School of Engineering, University of São Paulo, São Carlos, SP, 13560-970, Brazil.
J Environ Manage. 2025 Jan;373:123782. doi: 10.1016/j.jenvman.2024.123782. Epub 2024 Dec 19.
Contamination with potentially toxic metals and metalloids (PTMs) in mining areas poses significant environment and human health risks. Using biochar as an amendment can be a cost-effective and eco-friendly method to reduce PTM bioavailability in contaminated soils, thus lowering plant uptake. This study investigated biochar derived from the organic fraction of municipal solid waste (OFMSW) at three pyrolysis temperatures (300, 500, and 700 °C) and two application rates (1% and 5%, w/w) for the remediation of slag-contaminated soils from an old environmental liability in the Ribeira Valley (Brazil). The results showed Zn > Pb > Cu > As > Co > Cr > Cd > Ni pseudo-total concentrations in slag with concentrations of As, Cu, Pb, and Cd posing greater environmental risks due to their toxicity. The biochar addition exerted limited effects on chemical fractionation, likely due to soil alkalinity, and BC300 5% increased As availability. A 1% biochar addition improved maize (Zea mays) growth, whereas 5% BC500 and BC700 were phytotoxic. The highest bioconcentration factor (BCF) values were observed for Cr, Cu, Ni, and Zn, which are all essential nutrients for plants; however, translocation factor (TF) from roots to shoots was generally low. A combination of BCF and TF < 1 suggested mechanisms limiting PTM uptake and translocation in plants. Pb showed a high ecological risk potential (E), with hazard quotients (HQ) exceeding 1 for the slag. BC700 5% provided the most promising E for As, Pb, and Zn; however, it proved toxic to maize, highlighting the need for multidisciplinary research and biochar's potential in site remediation. Further treatments are necessary for enhancing the retention efficiency or exploring combinations with other organic or inorganic amendments.
矿区中潜在有毒金属和类金属（PTM）的污染对环境和人类健康构成重大风险。使用生物炭作为改良剂可能是一种经济高效且环保的方法，可降低污染土壤中PTM的生物有效性，从而减少植物对其的吸收。本研究调查了在三个热解温度（300、500和700°C）和两种施用量（1%和5%，w/w）下，由城市固体废物有机部分（OFMSW）衍生的生物炭对巴西里贝拉河谷一处旧环境责任场地的矿渣污染土壤进行修复的效果。结果表明，矿渣中锌>铅>铜>砷>钴>铬>镉>镍的准总浓度，其中砷、铜、铅和镉因其毒性而带来更大的环境风险。添加生物炭对化学分馏的影响有限，可能是由于土壤碱度，且BC300 5%增加了砷的有效性。添加1%的生物炭促进了玉米（Zea mays）的生长，而5%的BC500和BC700具有植物毒性。铬、铜、镍和锌的生物富集系数（BCF）值最高，而这些都是植物必需的营养元素；然而，从根到地上部分的转运系数（TF）通常较低。BCF和TF的组合<1表明存在限制植物对PTM吸收和转运的机制。铅表现出较高的生态风险潜力（E），矿渣的危害商（HQ）超过1。BC700 5%对砷、铅和锌显示出最有前景的E值；然而，它对玉米有毒，这凸显了多学科研究的必要性以及生物炭在场地修复中的潜力。需要进一步的处理来提高保留效率或探索与其他有机或无机改良剂的组合。
