A Review of Research Progress on Environmental Fate and Toxic Effects of Antibiotic-Heavy Metal Co-Contamination in Soil-Crop Systems

With the rapid development of industry, the issue of combined antibiotic-heavy metal contamination in farmland has become increasingly severe, threatening agricultural product safety and human health. However, current understanding of the environmental behaviors (migration, transformation, uptake, and accumulation) of combined antibiotic-heavy metal contamination in soil-crop systems and their toxic effects on soil organisms and crops remains incomplete, hindering the formulation of governance strategies for such contamination in farmland soils. This review reports on the current status of combined antibiotic-heavy metal contamination in Chinese farmland and the environmental fate and toxic effects in soil-crop systems. Existing studies show that combined contamination is observed in farmland soils, primarily sourced from livestock manure application, sewage irrigation, and pesticide use. Antibiotics and heavy metals can form stable complexes, whose environmental behaviors are influenced by soil organic matter, pH, and ion competition; after plant uptake, they mainly accumulate in roots and transfer to aboveground parts, with leafy vegetables exhibiting significantly higher enrichment capacity than legumes. Combined contamination exacerbates the spread of antibiotic resistance genes and heavy metal resistance genes through co-resistance mechanisms. Its toxicological effects are also more complex, presenting synergistic, antagonistic, or additive effects, leading to reduced soil microbial diversity, dysfunction of soil animal physiology, and oxidative stress damage in crops, thereby affecting crop growth and quality. However, current research has only reported short-term results for a few types of heavy metals, antibiotics, and crops, with unclear differences in outcomes under different doses and combinations. Future research is recommended in the aspects as follow: (1) Focusing on risk thresholds and precise management of combined antibiotic-heavy metal contamination, clarify safety thresholds through dynamic assessment models, develop traceability technologies for agricultural inputs and matching systems for pollution remediation, and achieve safe utilization of contaminated arable land; (2) Strengthening mechanistic studies on combined contamination under different combinations, exploring the environmental fate and toxic effect mechanisms at cellular, molecular, and genetic levels for different complexes formed by antibiotics and heavy metals, investigating the influencing mechanisms of environmental factors, advancing understanding of co-resistance gene transmission patterns, and cultivating and screening co-resistant crop varieties—thereby providing theoretical support for precise risk management of combined antibiotic-heavy metal contamination in farmland and promoting green agricultural development.