From Soil to Plate: Lithium and Other Trace Metals Uptake in Vegetables Under Variable Soil Conditions

The bioaccumulation of trace metals in edible crops is a key pathway of dietary exposure, with direct implications for environmental health and food safety. This study specifically investigated the bioaccumulation and soil-plant transfer of lithium (Li) in edible crops, alongside other selected trace metals (Cu, Mn, Sr, Zn), to understand its unique environmental mobility and dietary exposure risks in onion, garlic, green salad, cucumber, and zucchini cultivated across Romania. Forty-two paired samples of vegetable tissues and rhizosphere soils were collected from eleven agricultural regions, and were analyzed using spectroscopic techniques. Soils were predominantly neutral to slightly acidic, conditions that significantly affected metal mobility and uptake. Results revealed element-specific decoupling between soil and plant concentrations. Essential micronutrients (Zn, Cu) showed higher transfer factors, consistent with active physiological uptake, while toxic non-essential metals (Pb, Cd) remained below European regulatory thresholds, reflecting effective exclusion mechanisms. Lithium exhibited spatially heterogeneous transfer patterns, strongly influenced by local geochemical variability. Curvilinear soil-plant relationships for Fe, Zn, Sr, Mn, Cu, and Li further underscored the role of soil chemistry in shaping translocation. These findings establish a robust baseline for assessing dietary risks, confirming the current low-risk status of vegetables in the surveyed regions, and provide valuable guidance for sustainable agricultural management and food safety monitoring.