Geographic variation of Sr and S isotope ratios in bottled waters in Japan and sources of Sr and S.

The geographic distribution of the stable isotope ratio of Sr (87Sr/86Sr) is useful for identifying the provenance of drinking water, organisms, and agricultural products. To explore how environmental factors influence this ratio, we determined the 87Sr/86Sr, sulfur isotope ratio (δ34S), and elemental composition of 208 commercially available bottled waters in Japan, and compared them with the 87Sr/86Sr values of groundwater, rainwater, rocks, and vegetables from similar localities. We classified the bottled waters into seven categories based on the geology of their source aquifers. The 87Sr/86Sr and concentrations of several elements (Ca, K, Si, Rb, and Ba) of the bottled waters differed with the aquifer rock type and were well correlated with the 87Sr/86Sr of reported spring waters, indicating that bottled water, like other groundwater, reflects the lithology and chemistry of its aquifer. The 87Sr/86Sr of bottled water, taken as a proxy for groundwater, showed regional variations consistent with those of rocks and vegetables, demonstrating that an 87Sr/86Sr map of water and agricultural products has value for determining the production areas of these substances. However, the value and range of 87Sr/86Sr differed among these three materials, and the degree of the difference between groundwater and rock depended on the rock type. An analysis of geochemical data from rocks and rainwater suggests that groundwater contains Sr and additional S derived from atmospheric sources such as rainwater and sea salt aerosols. The atmospheric contribution of Sr to groundwater is greatest in areas of siliceous sedimentary rocks with low Sr concentrations and high resistance to weathering. A weak correlation of δ34S of bottled waters with 87Sr/86Sr indicates the usefulness of maps of combined Sr and S isotope ratios for groundwater provenance. This study shows that for accurate provenance determinations of groundwater, organisms, and agricultural products, it is essential to better quantify the contributions of Sr and S from the atmosphere as well as from rocks and human activities.

Ecological and cultural shifts of hunter-gatherers of the Jomon period paralleled with environmental changes.

OBJECTIVES: Holocene hunter-gatherers adapted to climatic and environmental changes over time. Carbon and nitrogen stable isotope analysis of human skeletal remains from the Inariyama shell mound of the Final Jomon period have revealed large dietary variations in the population. This study analyzed radiocarbon dates of these individuals to test temporal changes in diet and its relationship with tooth ablation. MATERIALS AND METHODS: Twenty-nine human skeletal remains from Inariyama were included in this study. Extracted bone collagen samples were purified to graphite. Then, radiocarbon dating of these samples was performed using the accelerator mass spectrometer. RESULTS: The radiocarbon ages of Inariyama ranged about, 3,230-2,140 cal BP and showed three peaks of occupation. In the early and late phases, terrestrial resource consumption and incisor extraction were observed, while marine resource consumption and canine extraction were observed in the middle phase. DISCUSSION: These temporal changes of diet and tooth ablation types occurred in parallel with climatic cooling and environmental change and help reveal how Holocene hunter-gatherers adapted to the changing environments.

Homogeneous diet of contemporary Japanese inferred from stable isotope ratios of hair.

The globalization of food production and distribution has homogenized human dietary patterns irrespective of geography, but it is uncertain how far this homogenization has progressed. This study investigated the carbon and nitrogen isotope ratios in the scalp hair of 1305 contemporary Japanese and found values of -19.4 ± 0.6‰ and 9.4 ± 0.6‰ (mean ± SD), respectively. Within Japan, the inter-regional differences for both isotope ratios was less than 1‰, which indicates low dietary heterogeneity among prefectural divisions. The carbon and nitrogen isotope ratios of the hair showed a significant correlation with the results of questionnaires on self-reported dietary habits. The carbon isotope ratios from Japan were lower than those in samples from the USA but higher than those in samples from Europe. These differences stem from the varying dietary proportions of food products originally derived from C3 and C4 plants. The dietary variation of Japan is as small as those of Europe and USA and smaller than those of some Asian countries. These results indicate that dietary homogeneity has progressed in Japan, which may indicate the influence from the spread of the Western-style diet and food globalization, although dietary heterogeneity among countries is still preserved.

Kantis: A new Australopithecus site on the shoulders of the Rift Valley near Nairobi, Kenya.

Most Plio-Pleistocene sites in the Gregory Rift Valley that have yielded abundant fossil hominins lie on the Rift Valley floor. Here we report a new Pliocene site, Kantis, on the shoulder of the Gregory Rift Valley, which extends the geographical range of Australopithecus afarensis to the highlands of Kenya. This species, known from sites in Ethiopia, Tanzania, and possibly Kenya, is believed to be adapted to a wide spectrum of habitats, from open grassland to woodland. The Kantis fauna is generally similar to that reported from other contemporaneous A. afarensis sites on the Rift Valley floor. However, its faunal composition and stable carbon isotopic data from dental enamel suggest a stronger C4 environment than that present at those sites. Although the Gregory Rift Valley has been the focus of paleontologists' attention for many years, surveys of the Rift shoulder may provide new perspective on African Pliocene mammal and hominin evolution.

Carbon isotope ratios of human tooth enamel record the evidence of terrestrial resource consumption during the Jomon period, Japan.

OBJECTIVE: Archaeological remains strongly suggest that the Holocene Japanese hunter-gatherers, the Jomon people, utilized terrestrial plants as their primary food source. However, carbon and nitrogen isotope analysis of bone collagen indicates that they primarily exploited marine resources. We hypothesize that this inconsistency stems from the route of protein synthesis and the different proportions of protein-derived carbon in tooth enamel versus bone collagen. Carbon isotope ratios from bone collagen reflect that of dietary protein and may provide a biased signal of diet, whereas isotope ratios from tooth enamel reflect the integrated diet from all macronutrients (carbohydrates, lipids, and proteins). METHODS: In order to evaluate the differences in inferred diet between the archaeological evidence and bone collagen isotope data, this study investigated carbon isotopes in Jomon tooth enamel from four coastal sites of the Middle to Late-Final Jomon period (5,000-2,300 years BP). RESULTS: Carbon isotope ratios of human teeth are as depleted as coeval terrestrial mammals, suggesting that C3 plants and terrestrial mammals were major dietary resources for the Jomon people. Dietary dependence on marine resources calculated from enamel was significantly lower than that calculated from bone collagen. The discrepancy in isotopic ratios between enamel and collagen and the nitrogen isotope ratio in collagen shows a negative correlation on individual and population levels, suggesting diets with variable proportions of terrestrial and marine resources. CONCLUSION: This study highlights the usefulness of coupling tooth enamel and bone collagen in carbon isotopic studies to reconstruct prehistoric human diet. Am J Phys Anthropol 158:300-311, 2015. © 2015 Wiley Periodicals, Inc.