Application of Sr-Pb isotopic difference of soils in yam origin identification

The aim of this work was to investigate the feasibility to trace geographical locations yam with the difference of Sr-Pb isotope in soils. The isotope ratios in the soil and partial yam samples were determined with thermal ionization mass spectrometer (TIMS). Statistical analysis was employed for geographical origin discrimination. The different soil samples were divided into five groups. The results showed that there was no significant differences between I and II groups of soil samples from different regions (P > 0.05). In addition, both groups of soil samples were collected at desertification serious areas close to the Yellow River, indicating the first two groups maybe from the same origin of the Yellow River sediment and should be bracketed together. Significant isotopic differences were found among different groups of soil samples (P < 0.01) : groups I and II have the lowest '8'7Sr/'8'6Sr ratios ranging from 0.715195 to 0.715623. Group III had the highest '8'7Sr/'8'6Sr ratios ranging from 0.717906 to 0.718594, the highest '2'0'6Pb/'2'0'4Pb ratios ranging from 18.643 to 18.765 and the highest '2'0'7Pb/'2'0'4Pb ratios ranging from 15.649 to 15.689. Group IV had moderate ratios of '8'7Sr/'8'6Sr, '2'0'6Pb/'2'0'4Pb and '2'0'7Pb/'2'0'4Pb with ranges 0.716004-0.716747, 18.642-18.700 and 15.634-15.650, respectively. Group V had relatively high '8'7Sr/'8'6Sr ratios ranging from 0.716081 to 0.718581, the lowest ratios of '2'0'6Pb/'2'0'4Pb (18.504-18.638) and '2'0'7Pb/'2'0'4Pb (15.572-15.614). The growing regions of Chinese yam can be effectively distinguished based on the isotopic difference with accuracy up to 94.1%, This research enriched the geographical origin traceability system of agricultural products. (authors)