Byeong-Yeol Song

Discrimination of cabbage (Brassica rapa ssp. pekinensis) cultivars grown in different geographical areas using 1H NMR-based metabolomics

Cabbage (Brassica rapa ssp. pekinensis) is one of the most popular foods in Asia and is widely cultivated in many countries for the production of lightly fermented vegetables. In this study, metabolomic analysis was performed to distinguish two cultivars of cabbage grown in different geographical areas, Korea and China, using ¹H NMR spectroscopy coupled with multivariate statistical analysis. Principal component analysis (PCA) showed clear discrimination between extracts of cabbage grown in Korea and China for two different cultivars (Chunmyeong and Chunjung). The major biochemicals (metabolites) that contributed to discrimination between cabbages grown in the two regions were 4-aminobutyrate (GABA), acetate, asparagine, leucine, isoleucine, O-phosphocholine, phenylacetate, phenylalanine, succinate, sucrose, tyrosine, and valine. These results suggest that the levels of the major metabolites that differ significantly between cabbages grown in these two areas were influenced by environmental factors such as climate and geology. Our study demonstrates that ¹H NMR based on metabolomics, coupled with multivariate statistics, can be applied to identify the regions of cultivation of various cabbage cultivars.

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 ((87)Sr/(86)Sr). Sequential leaching of soil showed that Sr in the exchangeable and carbonate fractions (bioavailable) had a lower (87)Sr/(86)Sr ratio than that in the silicate fraction, consistent with a low (87)Sr/(86)Sr ratio in the plant. Although the bedrock-soil-water-plant system is closely linked, statistical analysis indicated that (87)Sr/(86)Sr 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 (87)Sr/(86)Sr isoscapes in South Korea and first demonstrates that the agricultural product is strongly linked with the exchangeable fraction of soil and water.

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.

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.

Oxygen and hydrogen isotopic characterization of rainfall and throughfall in four South Korean cool temperate forests

ABSTRACT Understanding the isotopic composition of precipitation in a forested catchment is critical for ecohydrological studies. Changes in the water isotopes of rainfall were assessed during its passage through the canopy in throughfall, and the effect of different forest stands on the isotope composition of throughfall. In a cool temperate forest in Korea, rainfall and throughfall samples collected under Pinus densiflora (red pine), Castanea crenata (chestnut), Robinia pseudoacacia (black locust) and mixed stands (mix of these three species) were analysed for oxygen and hydrogen isotopes. Throughfall δ18O and δD were enriched compared to rainfall. A difference of δ18O and δD among throughfall may be related to the difference in interception–storage capacity of different species due to dissimilar canopy characteristics. Since isotopic composition of throughfall and rainfall are different due to canopy isotopic effects, use of rainfall isotopic signatures for ecohydrological studies in forested ecosystem can lead to biases.

Discrimination of the geographic origin of pork using multi-isotopes and statistical analysis

RATIONALE While global pork production has grown exponentially in recent decades to 109 Mt in 2010, methods aimed at verifying the geographic origin of pork products have yet to be thoroughly investigated. Here, we analyzed pork samples available in South Korea in order to discriminate their geographic origin. METHODS A total of the 37 pork samples originated from South Korea and other countries (Denmark, Germany, France, Spain, Canada and Mexico) were collected in order to classify their geographic origins using multi-isotope ratios, such as δ18 O, δ2 H, δ13 C, δ15 N values measured by IRMS, 87 Sr/86 Sr ratios measured by MC-ICP-MS, and multivariate statistical approaches. RESULTS There is a wide range of 87 Sr/86 Sr ratios in the pork samples, varying from 0.70779 to 0.71245, due to the lithology where the pork was raised. Canadian samples displayed the lowest δ18 O and δ2 H values mainly due to the latitude effect. Furthermore, the δ13 C values of European and Canadian samples were lower than those of Korean and Mexican samples, depending on whether the feed was composed of either C3 or C4 plants. The δ15 N values of the European and Canadian samples were much higher than those of the other samples, possibly resulting from the δ15 N values of the feed. CONCLUSIONS While differences in pork samples were observed that depended on geographic origin, this study suggests that more detailed investigations are needed to validate whether a combination of multi-isotope and multivariate statistical approaches is a valid method for determining the geographic origin of pork.