Trace Element Accumulation Patterns in Leafy Vegetables with Varying Heavy Metal Tolerance under Cadmium and Arsenic Stress

Leafy vegetables are a crucial component of the human daily diet. In recent years, research on heavy metal pollution in leafy vegetables has gradually increased, revealing differences in heavy metal accumulation in different vegetables and their potential risks to human health. Currently, some progress has been made in research on the response and regulatory mechanisms of leafy vegetables to heavy metal stress. This chapter examines the growth adaptation, heavy metal (Cd and As) accumulation, translocation dynamics, and mineral nutrient regulation in leafy vegetables exhibiting differential tolerance to heavy metal stress. Focusing on the challenge of combined Cd and As contamination, the study employed a hydroponic system to cultivate three high‑tolerance, four moderate‑tolerance, and one sensitive leafy vegetable variety under Cd and As exposure. Post‑harvest analysis assessed biomass production alongside the concentrations of Cd, As, and essential trace elements. Key findings reveal that: (1) Co‑exposure to Cd and As markedly enhanced the root‑to‑shoot translocation of Cd compared to single‑metal treatments, with translocation factors increasing by up to 83.83% in black bean sprouts and 503.2% in white radish sprouts. (2) While shifts in mineral nutrient concentrations under single and combined stress were generally consistent, the regulatory responses varied significantly across vegetable species. (3) High‑tolerance varieties, such as Pak choi, demonstrated a pronounced capacity for heavy metal accumulation under Cd/As stress, coupled with a positive regulation of mineral elements in root tissues. In contrast, sensitive species like pea sprouts often showed suppressed root mineral content—a likely adaptive strategy to limit heavy metal uptake. These insights elucidate critical resistance mechanisms to combined heavy metal pollution in leafy vegetables, providing a scientific basis for advancing phytoremediation strategies and guiding the safe production of vegetables in contaminated environments.