Phytoremediator Potential of Ipomea asarifolia in Gold Mine Waste Treated with Iron Impregnated Biochar

Growing environmental pollution in recent decades has been generating potentially toxic elements (PTE) which pose an ongoing threat to terrestrial and aquatic ecosystems and human health, especially in mining areas. Biochar and PTE-tolerant species have been used in soil remediation as they are environmentally friendly alternatives. This study aimed to assess the influence of acai seed biochar (Euterpe oleracea Mart), impregnated with iron (BFe) or not (BC), on the bioavailability of PTEs, in a multi-contaminated soil from a gold (Au) mining area in the Amazon, using Ipomea asarifolia as a plant test since it was naturally growing on the tailings. BC increased the soil pH while BFe reduced. Biochars increased PTEs in the oxidizable fraction (linked to soil organic matter). The use of BC and BFe improved the immobilization of PTEs and BC increased arsenic (As) in the easily soluble fraction in the soil. Moreover, plants grown with biochars showed lower dry matter yield, higher concentrations of PTEs and lower nutrient content than the control treatment. According to the phytoextraction and translocation factors, Ipomea asarifolia can be classified as a species with potential for phytostabilization of Zn and tolerant to other PTEs, mainly As.

Automated summary

Growing environmental pollution has led to the release of potentially toxic elements (PTE) that pose threats to ecosystems and human health, particularly in mining areas. Biochar and PTE-tolerant species have been used to remediate contaminated soil, offering environmentally friendly alternatives. This study assessed the impact of acai seed biochar on the bioavailability of PTEs in a multi-contaminated soil from a gold mining area in the Amazon. The results showed that biochar increased PTEs in the oxidizable fraction and improved their immobilization, but also led to lower dry matter yield and nutrient content in plants.