Phytoremediation of Heavy Metal Contamination in Agricultural Soils Surrounding Artisanal Mining Sites: A Review with Insights from Indigenous Plant Species in Benue State, Nigeria

Abstract

Artisanal and small-scale mining (ASM) has emerged as a significant source of heavy metal contamination in agricultural soils, particularly in sub-Saharan Africa. In Benue State, Nigeria, ASM activities release lead (Pb), cadmium (Cd), arsenic (As), and other toxic metals into surrounding farmlands, threatening food safety, ecosystem integrity, and human health. Conventional remediation approaches are often costly and ecologically disruptive, underscoring the need for sustainable alternatives. Phytoremediation, which employs plants to extract, stabilize, or detoxify contaminants, presents a cost-effective and environmentally compatible strategy that can be integrated into agricultural landscapes. This review consolidates evidence on heavy metal contamination from ASM in Nigeria and globally, discusses phytoremediation mechanisms, and evaluates indigenous plant species in Benue State with potential for remediation based on tolerance and uptake traits. Case studies are compared against World Health Organization (WHO) and Food and Agriculture Organization (FAO) soil quality thresholds to highlight contamination risks and remediation needs. Challenges such as biomass management, land-use competition, limited farmer awareness, and weak policy support are identified, alongside opportunities for integrating phytoremediation into agroecological restoration and rural development strategies. Research gaps are highlighted, including systematic screening of native species, microbial-assisted phytoremediation, and field-scale validation trials. By linking global advances with local insights, this review positions phytoremediation as a viable tool for mitigating ASM-related soil degradation, enhancing food security, and informing environmental policy in Benue State and beyond.