chemical fractionation of copper and zinc after addition of conocarpous waste biochar to a drill cutting

Background: drill cutting (dc) are large amount of waste generated in gas and oil exploration and production activities that contains toxic substances, especially heavy metals. this study aimed to use conocarpus waste (cw) biochar to investigate its effects on changes in chemical forms and stabilization and distribution of cu and zn in dc samples of ahvaz oil field at different incubation times. methods: in order to study the effects of cw biochar at different rates (0, 2, 5, and 10% w/w) and four incubation times (1, 2, 4, and 8 weeks) for adsorption and chemical fractionation of copper (cu) and zinc (zn) in dc of ahvaz oil field in southwestern iran. an experiment was conducted as a factorial in a completely randomized designing in three replication. sequential extraction procedure of tessier was applied for the determination of heavy metals fraction. results: application of biochar significantly (p<0.05) increased the ph, soil organic carbon (soc), electrical conductivity (ec), and cation exchange capacity (cec) especially at the 10% application rate. after the addition of cw biochar, the exchangeable (ex) and carbonate (car) fractions of cu and zn, respectively decreased (p≤0.05) significantly while organic matter (om) bound, oxides (ox) bound, and residual (res) fraction were increased. conclusion: the cw biochar can be a low-cost and effective amendment in immobilizing the cu and zn, and also effectively to reducing their mobility in dc