Effects of Biochar and Apatite on Chemical Forms of Lead and Zinc in Multi-Metal-Contaminated Soil after Incubation: A Comparison of Peanut Shell and Corn Cob Biochar

Abstract

Heavy metal pollution in soils caused by mining activities is a severe issue worldwide. It is necessary to find a suitable approach to mitigate heavy metal-contaminated soil. Yet little is known about how soil amendments affect the chemical forms of heavy metals. Biochar produced from peanut shells (PSB300) and corn cob (CCB300) at 300 °C, and apatite (AP) were applied at various ratios to investigate their ability to adsorb lead (Pb) and zinc (Zn) in contaminated soil. The Pb and Zn’s chemical fractions were analyzed utilizing Tessier’s sequential extraction procedure and quantified using inductively coupled plasma mass spectroscopy. The one-month amendment incubation of biochar and AP could significantly diminish Pb and Zn’s exchangeable fractions, and CCB300 showed a slightly better effect on declining the exchangeable fractions of Pb and Zn than PSB300, which might be attributed to the higher values of OC and EC of CCB300 than those of PSB300. Moreover, the amendments could also transform the exchangeable fractions of Pb and Zn into stable fractions, resulting in immobility in natural conditions. Thus, PSB300 and CCB300 and the mixture of biochar/apatite could be hopeful amendments for immobilizing heavy metals in heavy metal multi-metal-contaminated field soil.

Utilization of banana waste biochar to reduce heavy metal contamination in soil and maize plants

“…In addition to soil type, heavy metals, biomass, application rate, and pyrolysis temperature, different biochars also have different physicochemical properties and thus exhibit different properties. It depends on the effect of the chemical fraction of heavy metals (Fu et al, 2023;Vuong et al, 2023). For example, biochar produced at 300 °C has a higher soluble phosphate concentration than biochar pyrolyzed at 400 °C.…”

Lead and zinc chemical fraction alterations in multi-metal contaminated soil with pomelo peel biochar and biochar/apatite incubation

“…Each soil sample was collected at intervals of approximately five meters, with an average weight of about two kilograms and dimensions measuring approximately 30 cm in width, 30 cm in length, and ranging from 0 to 20 cm in depth. To ensure homogeneity and representativeness, five subsamples were collected and thoroughly mixed to form a composite soil sample [35].…”