Tracing the geographical origin of bottled water collected in South Korea via isotopic and elemental analyses.

RATIONALE: The production of bottled water requires a forensic discriminant technique that enables the identification of the brands or accidents caused by intended contaminants. The bottled water poisoning crimes have drawn much attention, and such crimes may recur in the future. The water is colorless and odorless, and thus it is difficult to detect contaminated water through visual observation. Thus, bottled water can be easily exploited for poisoning, and a method for tracing their origin is currently required. METHODS: In this study, a total of 27 brands of bottled water samples were analyzed to determine stable oxygen isotopes, strontium isotopes, major and trace elements. The geographical origin of the water was traced based on the climatic and geographical characteristics of the location from where water was sourced, which was assumed to be reflected in the bottled water. Furthermore, we investigated whether this method can be applied to identify bottled water products. RESULTS: The results demonstrated that the characteristics of the bottled water, including the oxygen stable isotope ratios, reflect the latitude and altitude of bottled water source in South Korea, from the high-latitude region to the coastal regions. In addition, the results indicated that excellent discrimination was achieved using strontium isotopes to identify source areas with different types of bedrock, complex underlying lithologies, and ocean areas in South Korea. A statistical method based on discriminant analysis was applied to measure trace elements, and the results effectively reflected the characteristics of water-rock interactions (cross-validated classification probability: ≥92%). CONCLUSIONS: These data suggest that the geographical characteristics of the source area are well reflected in commercial bottled water in South Korea. The proposed analytical methods can be utilized to trace the geographical origin of different bottled water samples and identify bottled water products used in poisoning crimes.

Preliminary stable isotope analyses for propellant discrimination in shotshells.

RATIONALE: This study aimed to develop methods to determine the identity and trace the origin of propellants used in shotshells. Specifically, the use of organic component and stable isotope analysis techniques, such as bulk stable isotope analysis (BSIA) and compound-specific isotope analysis (CSIA) techniques, for the study of shotshell propellants was investigated. METHODS: Nine samples of shotshell propellants from different manufacturing countries and brands were analyzed for explosive and additive components by gas chromatography/mass spectrometry and thin-layer chromatography. BSIA of the propellants was achieved using elemental analysis/isotope ratio mass spectrometry without a pretreatment process. For the CSIA of nitroglycerin, double-base powder propellants were extracted with ether, and the isotope ratios of carbon and nitrogen were measured by gas chromatography/isotope ratio mass spectrometry. RESULTS: Nine samples drawn from seven brands in four countries were classified into five groups by organic component analysis, while eight classification groups were identified by BSIA. Thus, two samples could not be distinguished from each other by either BSIA or organic component analysis. Subsequently, with the use of results obtained with CSIA for nitroglycerin, all the samples could be classified into different groups. These findings suggest that the nine propellant samples were all composed of different ingredients or raw materials from different sources. CONCLUSIONS: Stable isotope ratio analyses were performed for propellant discrimination. The combined BSIA, CSIA and organic component analysis techniques were able to successfully distinguish the nine shotshell propellants from seven brands sourced from four different countries, and the results suggested that the samples contained different ingredients or raw materials from different sources. We therefore can conclude that reliable results can be obtained using combined isotope analysis methods such as CSIA and BSIA for origin tracing and identity determination.

Major, trace and rare earth elements dynamics in decomposing litters on successional sites in a cool temperate region of South Korea.

Evaluating the decomposition-based change dynamics of various elements in plant litter is important for improving our understanding about their biogeochemical cycling in ecosystems. We have studied the concentrations of major, trace, and rare earth elements (REEs) (34 elements) in green tissue litter, and soil and their dynamics in the decomposing litters of successional annual fleabane (Erigeron annuus) and silvergrass (Miscanthus sinensis). Concentrations of major and trace elements in the litter of annual fleabane were 1.02-2.71 times higher compared to silvergrass. For REEs the difference between the two litter types for elements studied was in the range of 1.02-1.29 times. Both the litters showed a general decrease in the concentrations of elements in the initial stages of decomposition (60-90 days). All the major and trace elements (except for Na) in silvergrass showed a net increase in concentration at the end of the decomposition study (48.9-52.5% accumulated mass loss). Contrastingly, a few trace elements (Mn, Mo, Sr, Zn, Sb, and Cd) in annual fleabane showed a net decrease in their concentrations. For REEs, there was an increase in concentrations as well as in net amounts in both litter types. Similarities observed in the dynamics together with high and significant correlations among them likely suggest their common source. The higher concentrations of REEs in soil likely suggest its role in the net increase in REEs' concentrations and amount in litter during decomposition.

Datasets for spatial variation of O and H isotopes in waters and hair across South Korea.

The data presented here include the results of oxygen (δ18O) and hydrogen (δ2H) isotope analyses of water and human scalp hair samples collected from throughout the South Korea. The purpose of data collection was to generate isoscapes of oxygen and hydrogen isotopes for South Korea. To achieve the objective, we collected human scalp hair and three different types of water samples: groundwater, stream water and tap water. The data presented in the article are raw isotope data of water and hair samples in tabulated manner and interpolated isoscapes generated using those data. Further information related to the datasets and discussion about them can be found in the related research article entitled "Spatial variations in oxygen and hydrogen isotopes in waters and human hair across South Korea" [1].

Spatial variations in oxygen and hydrogen isotopes in waters and human hair across South Korea.

The spatial distribution of isotopic signatures in the form of isoscape is a valuable tool to map their spatial heterogeneity in various environmental settings. However, only limited information about δ18O and δ2H in water across South Korea is available and to our knowledge no study so far has tried to examine the isotopic heterogeneity of tap water and human scalp hair in South Korea. Here, we present the first national scale analyses of stream water, groundwater, tap water, and human scalp hair isoscapes for South Korea. Stream water, groundwater, tap water, and human scalp hair samples were collected from across South Korea. These samples were analyzed for δ18O and δ2H, and the isotopic data were then used to generate interpolated δ18O and δ2H isoscapes for South Korea. The results of linear regression analyses showed strong and significant relationships between δ18Ohair and δ18Owater (R2 = 0.83, P < 0.002) and between δ2Hhair and δ2Hwater (R2 = 0.74, P < 0.006), primarily reflecting a close co-relationship between water and hair. The slopes of linear regressions for δ18O (Δδ18Ohair/Δδ18Owater) and δ2H (Δδ2Hhair/Δδ2Hwater) suggested that approximately 27% of hydrogen and 36% of oxygen in hair keratin were derived from the local drinking water. Interpolated δ18O and δ2H isotope maps of stream water, groundwater, and tap water samples collected from across South Korea showed similar spatial patterns of isotope variability. These samples showed a clear latitudinal gradient with high isotopic values in the south which progressively decrease toward the north. The same trends were observed in hair isoscapes as well, and had gradients matching the isotopic pattern of water samples. The strong relationship between water and human hair, and the consistent spatial pattern between them suggest that hair isotope signatures in South Korea can be used in provenance- and forensic-related activities.

Trends of major, minor and rare earth elements in decomposing litter in a cool temperate ecosystem, South Korea.

The decomposition dynamics of 34 different elements in four different litter types (foliar and woody litter) from Pinus densiflora (Korean red pine) and Castanea crenata (Korean chestnut) was investigated in a cool temperate ecosystem using the litterbag method. Two contrasting trends were observed in the dynamics of elements with accumulated mass loss of litter and carbon. Leaf litter of Korean chestnut, which was richer in elements, showed a general decrease in concentrations of elements with accumulated mass loss of litter and carbon on a dry mass basis during decomposition in the field. Other litter types, with initially lower concentrations of elements, exhibited an increase in concentration on a dry mass basis during field incubation. Highest relative increase in the concentration was noticed for the minor elements, and for the woody litters. Concentrations of major and minor elements increased by factors ranging from 1.07 for antimony (Sb) to 853.7 for vanadium (V). Rare earth elements (REE) concentrations increased by factors ranging from 1.04 for scandium (Sc) to 83.5 for thorium (Th). Our results suggest that litter type plays an important role for nutrient dynamics. Results from principal component analysis for major, minor, and rare earth elements showed grouping of elements and high correlation among them (P < 0.05), which suggests a common source. At both sites, element concentrations were high in the soil, especially for REE. This suggests that increase in element concentrations during field incubation probably was due to transfer of elements from soil to the overlying decomposing litter.

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.

Tracing the source of methomyl using stable isotope analysis.

RATIONALE: Pesticide self-poisoning is a major method of suicide in many agricultural communities worldwide. In addition, there are a number of known crime cases related to people being harmed by insecticides. Methomyl, a prohibited insecticide in the Republic of Korea, has high toxicity and is frequently used for self-poisoning. In this study, we investigated the source of origin of methamyl in a fatal poisoning case using stable isotope ratio analysis. METHODS: Two bottles of Soju from a crime scene were seized and nine different brands of methomyl products were collected from the neighborhood for analysis. In addition, the gastric contents and energy drink from the person who had committed suicide were analyzed. Isotope analysis using GC/Isolink/IRMS was conducted to determine the source of the methomyl by comparing their carbon and nitrogen isotope ratios. Linear discriminant analysis was utilized to verify the results. RESULTS: Isotope ratio analysis showed that the isotope ratio ranges of methomyl found in the Soju, the gastric contents of the suicide victim, and the energy drink bottle were similar to those of a seized methomyl product, Samgong methomyl 2011 (SG11). Thus, it was assumed that SG11 was used in this fatal poisoning case. CONCLUSIONS: This study demonstrates the potential of stable isotope ratio analysis for the determination of insecticide origin in fatal poisoning cases.

Early-stage changes in natural (13)C and (15)N abundance and nutrient dynamics during different litter decomposition.

Decomposition, nutrient, and isotopic (δ(13)C and δ(15)N) dynamics during 1 year were studied for leaf and twig litters of Pinus densiflora, Castanea crenata, Erigeron annuus, and Miscanthus sinensis growing on a highly weathered soil with constrained nutrient supply using litterbags in a cool temperate region of South Korea. Decay constant (k/year) ranged from 0.58 to 1.29/year, and mass loss ranged from 22.36 to 58.43 % among litter types. The results demonstrate that mass loss and nutrient dynamics of decomposing litter were influenced by the seasonality of mineralization and immobilization processes. In general, most nutrients exhibited alternate phases of rapid mineralization followed by gradual immobilization, except K, which was released throughout the field incubation. At the end of study, among all the nutrients only N and P showed net immobilization. Mobility of different nutrients from decomposing litter as the percentage of initial litter nutrient concentration was in the order of K > Mg > Ca > N ≈ P. The δ(13)C (0.32-6.70 ‰) and δ(15)N (0.74-3.90 ‰) values of residual litters showed nonlinear increase and decrease, respectively compared to initial isotopic values during decomposition. Litter of different functional types and chemical quality converged toward a conservative nutrient use strategy through mechanisms of slow decomposition and slow nutrient mobilization. Our results indicate that litter quality and season, are the most important regulators of litter decomposition in these forests. The results revealed significant relationships between litter decomposition rates and N, C:N ratio and P, and seasonality (temperature). These results and the convergence of different litters towards conservative nutrient use in these nutrient constrained ecosystems imply optimization of litter management because litter removal can have cascading effects on litter decomposition and nutrient availability in these systems.

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.