Effects of bedrock on the chemical and Sr isotopic compositions of plants

This study was conducted to investigate the relationship between the chemical and isotopic compositions of plants and the lithology of their growth location. This relationship is one of the principles underlying the geographical discrimination used for agricultural, forestry, and food products. Locations in South Korea with solely basaltic (Jeju), granitic (Gongju), and carbonate (Yeongwol) rocks were selected as test sites, and bedrocks, soils, and plants in each location were sampled. The multi-element compositions and Sr isotope ratios (⁸⁷Sr/⁸⁶Sr) were analyzed for all samples, including various soil fractions (exchangeable, carbonates, silicates) and plant parts (tree leaves, vegetable leaves, and fruits). Based on a preliminary statistical analysis (ANOVA), Ca, Mg, K, Al, Sr concentrations, and ⁸⁷Sr/⁸⁶Sr ratios were selected as key variables with greater variability with location. Using these variables, a multivariate statistical analysis was conducted, and three soil fractions and plant parts were successfully discriminated according to their geographical origin (i.e., bedrock type) with statistical significance. The results indicated that Sr isotope ratios of bedrocks can be preserved in soils (except in silicate fractions) and plants throughout weathering and plant physiological processes, and are the most critical variable in the tracing of bedrock characteristics.