Accumulation patterns and health risk assessment of potentially toxic elements in the topsoil of two sloping vineyards (Tokaj-Hegyalja, Hungary)

Abstract

Abstract Purpose In agricultural soils, accumulation and bioavailability patterns of potentially toxic elements (PTEs) are key ecological and health risk issues, especially in metal-based crop protection systems such as those applied in vineyards. However, PTE levels in the topsoils of historical wine-growing regions of Hungary have been scarcely studied so far. The specific goals of this research were to assess the accumulation tendencies and bioavailability of PTEs complemented with human health risk assessment in two sloping vineyards with pH-contrasted soils in Tokaj-Hegyalja, Hungary, and under different farming practices. Methods Composite topsoil (< 20 cm) and borehole samples were collected from two vineyards and local forests. The total and bioavailable PTE contents (Zn, Pb, Co, Ni, Cr, Cu) were analyzed following digestion in aqua regia and extraction with a strong chelating agent (0.05 M Na2-EDTA). Enrichment factors (EFs) were calculated based on Fe as a reference element and the local uncultivated soil. The hazard indexes (HIs) for outdoor workers, children, and adults living in residential areas near the vineyards were calculated to assess the health risks associated with the target PTEs. Results Higher PTE contents were observed in the organic vineyard (near Tokaj) compared to the conventional one (near Tállya), except for Cu and Pb. The EFs confirmed that the duration of Cu-fungicide applications mainly determines the soil-bound Cu levels, with an average of 2.6 in the 28-year-old organic vineyard and 9.6 in the more than 100-year-old conventional vineyard. The PTEs predominantly accumulated at the top of the hillslope in Tállya, while in Tokaj, a general trend of downslope accumulation of PTEs can be noticed. Bioavailable Cu reached a maximum of 50% of total Cu at the top of the hillslope (Tállya) and positively correlated with soil organic matter content. Iron/Mn oxides, total Ca content, and soil pH show a significant correlation with the PTE total contents (other than Cu); meanwhile, their bioavailability is mainly influenced by Mn oxides. The calculated HIs are less than 1, indicating no elevated health risk. Total Cr is the major contributor to the HI in both vineyards, reaching 79.0% (Tokaj) and 49.7% (Tállya). Conclusion Overall, the accumulated Cu contents mainly depended on the vineyard age, while farming practices and terrain morphology play a minor role in its spatial distribution. The further accumulation of PTEs, especially in high-metal hotspots within the vineyards, may ultimately cause toxicity to re-planted grapevines, soil biota, and, in the longer term, farmers and residents.