Mukesh Kumar Gautam

Determining the geographical origin of Chinese cabbages using multielement composition and strontium isotope ratio analyses

Recently, the Korean market has seen many cases of Chinese cabbage (Brassica rapa ssp. pekinensis) that have been imported from China, yet are sold as a Korean product to illegally benefit from the price difference between the two products. This study aims to establish a method of distinguishing the geographical origin of Chinese cabbage. One hundred Chinese cabbage heads from Korea and 60 cabbage heads from China were subjected to multielement composition and strontium isotope ratio ((87)Sr/(86)Sr) analyses. The (87)Sr/(86)Sr ratio differed, based on the geological characteristics of their district of production. In addition, the content of many elements differed between cabbages from Korea and China. In particular, the difference in the content of Sr and Ti alone and the combination of Sr, Ca, and Mg allowed us to distinguish relatively well between Korea and China as the country of origin. The present study demonstrates that the chemical and Sr isotopic analyses exactly reflect the geology of the production areas of Chinese cabbage.

A multianalytical approach for determining the geographical origin of ginseng using strontium isotopes, multielements, and 1H NMR analysis.

Asian ginseng (Panax ginseng C.A. Meyer) is widely used as an Oriental medicine in the East Asian regions, particularly Korea and China. In the study, the strontium isotope ratios ((87)Sr/(86)Sr), multielements, and metabolite profiles of 35 ginseng samples collected from Korea and China were examined in an attempt to develop a method to distinguish the origin of ginsengs from the two countries. A multivariate statistical approach was performed to analyze the multielements and the (1)H nuclear magnetic resonance (NMR) data. Results of a t-test for Mg, Fe, Al, and Sc showed significant variation between Korean and Chinese ginsengs, indicating potential tracers for discriminating them. Discriminating between the ginsengs from the two countries was generally successful when both the (87)Sr/(86)Sr ratios and rare earth element (REE) contents were used together. Moreover, principal component analysis (PCA) derived from the (1)H NMR data revealed a significant separation between the ginsengs originating from the two countries. The major metabolites responsible for differentiation were sugars such as glucose, xylose, and sucrose. The results suggest that this multiplatform approach offers a comprehensive method to distinguish the origin of ginsengs.

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

AbstractThis 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.

Geographic Origins of Korean and Chinese Kimchi Determined by Multiple Elements

An elemental analysis was performed on 30 Korean and Chinese kimchi samples in combination with strontium (Sr) isotope ratio measurements to develop a method for tracing the geographic origins of Korean and Chinese kimchi. We found a distinct difference between Korean and Chinese kimchi in such specific elements as K, Na, Ca, Ba, Sr, Zn, Li, and Sc, but no significant difference in the Sr isotope ratio. A comparative analysis was performed with washed kimchi (containing no submaterial) and unwashed kimchi to evaluate the effect of submaterials on the determination of geographic origin. A linear discriminant analysis provided a clear distinction between Korean and Chinese kimchi. The results indicate that combining multi-elemental and statistical analyses has the potential to determine the geographic origins of such processed food as kimchi.

Isotopic composition of throughfall nitrates in suburban forests with different vegetations

Isotopic studies on throughfall (precipitation shed from foliages) nitrates are rare despite their importance as a major nitrogen source in forest ecosystems. This study was conducted to examine a seasonal and species-related variability in isotopic composition of throughfall nitrates and its implications on forest nitrate sources. Event based throughfall samples were collected for a year from three locations (Chestnut, Pinus, and Mixed forests) along with rainfall (uninterrupted precipitation to the ground) samples from an open canopy location, and analyzed for nitrogen and oxygen isotopic composition of dissolved nitrates. δ15NNO3 and δ18ONO3 values of rainfall nitrates were greater during the non-growing season (Nov.~Mar.) than the growing season (Apr.~Oct.) as expected from the atmospheric nitrate cycles and associated isotopic effects. Although the isotopic composition of throughfall nitrates followed a similar seasonal pattern with that of rainfalls, their δ15NNO3 and δ18ONO3 values were consistently higher (Sep.~Dec.) or lower (Jan.~Apr.) than rainfalls and showed an abrupt decrease in July, possibly related to the incorporation of nitrates from soil and foliar origin. Isotopic composition of throughfall nitrates also varied systematically with vegetation types, indicating isotopic effects associated with nitrate uptake and release at the forest canopy. The seasonal and species-related variability in the isotopic composition of throughfall nitrates indicated combined effects of atmospheric NOx cycles, dry and wet depositions, and species-specific isotopic effects associated with nitrate use.

Site related δ 13 C of vegetation and soil organic carbon in a cool temperate region

BackgroundWhile soil organic matter 13C isotope helped evaluate vegetation-related change in soil organic carbon (SOC), less is understood about δ13CSOC and SOC in reforested ecosystems.MethodsTo assess native vegetation (vegetation predominant in the region prior to deforestation) and the effect of reforestation on SOC, we studied δ13C of plant, litter and SOC in reforested red pine, chestnut, mixed stands and silvergrass, and compared them with bare land.ResultsAfter 40 years, reforestation increased SOC by 82.86% and 24.90% in 0–10 cm and by 45.96% and 24.85% in 0–30 cm depths in chestnut and mixed stands, respectively. However, SOC content decreased in red pine and silvergrass in both 0–10 cm and 0–30 cm depths. δ13CSOC in red pine, chestnut, mixed stands, and bare land increased (∆13C 2.4–5.9‰) from L-layer to 1 m soil depth and indicated C3 vegetation was long-term component of the area. In contrast, δ13CSOC values are more depleted than expected in silvergrass (∆13C −9.7‰), and similar to reforested soil. This indicates its recent colonization in area occupied previously by C3 species. Regression coefficient-β, indicated isotopic fractionation during SOC decomposition/humification and physical mixing that occurs during C turnover in well-drained soil. The δ13CSOC based estimated proportion of new carbon (fnew) and decomposition rate (k) were higher in chestnut and mixed stand, and their turnover time was shorter than red pine and silvergrass.ConclusionResults suggest that reforested species impact soil C decay rate and turnover, and soil ability to maintain SOC stocks post deforestation.

Origin assessment of domestic and imported beef sold in the Korean markets using stable carbon and oxygen isotopes

In this study, stable carbon and oxygen isotope data were used to determine the country of origin of imported beef circulating in the Korean market. Using carbon isotopes closely related to the animal diets, Korean beef could easily be distinguished from United States (US) and New Zealand beef. However, oxygen isotopes were more effective in distinguishing the Korean from Australian beef. The oxygen isotopes have specific characteristics reflecting the latitude where cattle feed. Statistical analyses indicate that analyzing both carbon and oxygen isotopes is very useful to assess the country of origin of beef sold in the Korean market. Additionally, we compared the carbon isotopic compositions of defatted and non-defatted beef to evaluate the effect of fat content on carbon isotope values. Our results suggest that by using muscles or tissues that have small amounts of fat, carbon isotope analysis of beef samples may be performed without the inconvenient conventional pretreatment procedure, allowing for easier and faster isotopic analysis.