Geochemical background of some trace elements in Atlantic Forest soils in a cocoa-producing region and its implications for human health and food safety

Abstract

The background values for trace elements (TEs) in soils are crucial for environmental monitoring and food safety, as establishing quality reference values (QRVs) and help distinguish natural from anthropogenic sources. Brazil is the sixth-largest cocoa producer globally, with plantations concentrated in northeast and north regions. However, data on natural TEs concentrations in soils remain scarce, posing a significant challenge for food safety, human health, and environmental regulations. This study aims to determine natural TEs concentrations and establish QRVs for selected elements. Surface soil samples were collected from 38 native forest units and analyzed using exploratory, univariate, and multivariate statistical methods. Compared to soils around the world and from northern and northeastern Brazil, Ba and Cd (66.8 and 2.7 mg kg⁻¹, respectively) exhibited the highest mean concentrations, except when compared to European soils. The results highlight that TEs concentrations in Atlantic Forest soils of southern Bahia differ due to geological diversity. Pedogenetic processes influenced TEs distribution, following the order: Fe > Ti > Ba > V > Cr > Zn > Cu > Co > Ni > Pb > Cd > Sb > Mo. QRVs were established using the 75th and 90th percentiles. Future research could integrate ecological and human health risk indices in cocoa-cultivated areas, considering soil, litter, plant tissues, and almonds. This approach would enhance understanding of TEs behavior under varying edaphic conditions, ultimately strengthening environmental monitoring strategies and food safety regulations.