Phytoremediation of Heavy Metal-Contaminated Soils: Evaluating Agronomic Crops, Hyperaccumulators, and Halophytes

Heavy metal contamination in soils is a pressing environmental issue driven by industrial activities, mining, wastewater irrigation, and the excessive application of agrochemicals. Phytoremediation – the use of plants to extract, immobilize, or detoxify heavy metals – offers a sustainable and cost-effective approach to soil remediation. A bibliometric analysis using Scopus (as of May 2025) revealed 24,982 publications on phytoremediation, reflecting the growing global interest in this eco-friendly strategy. Research output has surged from just 4 publications in 1994 to over 2,300 in 2024, with the highest contributions from China (6,724), India (3,922), and the United States (2,973). This review evaluates the phytoremediation potential of three key plant groups: agronomic crops, hyperaccumulators, and halophytes. Among the most frequently studied species are Brassica juncea (5,349 publications), Zea mays (5,210), Brassica napus (3,957), and Helianthus annuus (2,969), favored for their high biomass and moderate metal uptake (e.g. ~20 mg kg Cd in maize, ~50 mg/kg in Brassica). Hyperaccumulators such as Thlaspi caerulescens and Alyssum spp. can accumulate over 1,000 mg/kg of Zn and Ni, and up to 100 mg/kg of Cd in shoot tissues, with the term “hyperaccumulator” appearing in 8,006 publications. Halophytes like Atriplex and Suaeda spp. are effective in saline and co-contaminated environments, accumulating 50–200 mg/kg of Cd, Pb, or Zn, and have been mentioned in 1,936 publications – highlighting their emerging relevance in phytoremediation research. Recent research shows a shift toward integrating traditional crops with stress-tolerant plants to improve phytoremediation. Hyperaccumulators efficiently concentrate metals, while agronomic crops remove contaminants through high biomass. Interest in halophytes is rising due to their tolerance of saline, metal-contaminated soils, an issue worsened by climate change, highlighting their promise for reclaiming marginal lands and supporting climate-resilient remediation.