Determination of the Source of Bioavailable Sr Using ⁸⁷Sr/⁸⁶Sr Tracers: A Case Study of Hot Pepper and Rice

The geographical origin of agricultural products has been intensively studied, but links between agricultural products and the environments are poorly established. Soils, water (streamwater and groundwater), and plants (hot pepper, Capsicum annuum; and rice, Oryza sativa) were collected from all regions of South Korea and measured Sr isotope ratios (⁸⁷Sr/⁸⁶Sr). Sequential leaching of soil showed that Sr in the exchangeable and carbonate fractions (bioavailable) had a lower ⁸⁷Sr/⁸⁶Sr ratio than that in the silicate fraction, consistent with a low ⁸⁷Sr/⁸⁶Sr ratio in the plant. Although the bedrock–soil–water–plant system is closely linked, statistical analysis indicated that ⁸⁷Sr/⁸⁶Sr ratios of the plant showed the greatest agreement with those of water and the exchangeable fraction of soil. This study is the first report of ⁸⁷Sr/⁸⁶Sr isoscapes in South Korea and first demonstrates that the agricultural product is strongly linked with the exchangeable fraction of soil and water