Isotopes in Environmental and Health Studies最新文献

There is an increasing global demand for regional and organic produce. However, the growth of these markets depends on consumers' trust. Thus, novel methods must be developed to aid the verification of the origin of produce. We built on our previous study to identify the geographical origin and production method of animal-derived food products. Thirty-samples of eggs, 99 of milk, 34 of beef, and 62 of pork were collected from different regions in central Germany and analysed for their stable isotopic composition. The analysis followed a single-variate authentification approach using five isotope signatures, δ¹⁸O, δ²H, δ¹³C, δ¹⁵N, and δ³⁴S. The best-performing indicators for verification of the geographical origin were δ¹⁵N and δ³⁴S for beef; δ¹⁸O, δ²H, and δ¹³C for milk, and δ²H and δ¹³C for pork. These tracers indicated statistically significant differences among regions with the exception of pork; the results recorded for eggs were inconclusive. It was possible to distinguish between production methods by means of δ¹⁵N and δ³⁴S (beef); all five tracers (eggs), and δ¹³C, δ¹⁵N, and δ³⁴S (milk). This study demonstrated how the analysis of stable isotopes can be employed to determine the geographic region of origin and production method of animal-derived products in Germany.

After the atmosphere, the ocean is the most well-mixed and homogeneous global geochemical reservoir. Both physical and biological processes generate elemental and isotope variations in seawater. Contrasting geochemical behaviors cause elements to be susceptible to different fractionation mechanisms, with their isotopes providing unique insights into the composition and evolution of the ocean over the course of geological history. Supplementing the traditional stable isotopes (H, C, O, N, S) that provide information about ocean processes and past environmental conditions, radiogenic isotope (Sr, Nd, Os, Pb, U) systems can be used as time markers, indicators of terrestrial weathering, and ocean water mass mixing. Recent instrumentation advances have made possible the measurement of natural stable isotope variations produced by both mass-dependent and mass-independent fractionation for an ever-increasing number of metal elements (e.g. Li, B, Mg, Si, Ca, V, Cr, Fe, Ni, Cu, Zn, Se, Mo, Cd, Tl, U). The major emphasis in this review is on the isotopic composition of the light elements based on a comparatively large literature. Unlike O, H and S, the stable isotopes of C, N and Si do not have a constant isotopic composition in the modern ocean. The major cations Ca, Mg, and Sr fixed in carbonate shells provide the best proxies for reconstruction of the composition of the ocean in the past. Exhibiting large isotope enrichments in ocean water, B and Li are suitable for the investigation of water/rock interactions and can act as monitors of former oceanic pH. The bioessential elements Zn, Cd, and Ni are indicators of paleoproductivity in the ocean. Characteristic isotope enrichments or depletions of the multivalent elements V, Cr, Fe, Se, Mo, and U record the past redox state of the ocean/atmosphere system. Case studies describe how isotopes have been used to define the seawater composition in the geological past.

Radium-226 detection in sediment samples is generally executed by means of gamma-ray spectrometry. Data evaluation relies (besides the 186.2 keV ²²⁶Ra gamma peak) on the combined analysis of major gamma peaks that are produced by the short-lived radon (²²²Rn) daughters ²¹⁴Pb and ²¹⁴Bi. Precondition for this detection approach is equilibrium decay of all members of the decay chain between ²²⁶Ra and ²¹⁴Bi. In closed systems, this equilibrium is reached after about five half-lives of ²²²Rn (19 days). However, a closed system can only be guaranteed if the capsule which contains the sample prevents diffusive escape of radon. Such radon-tightness cannot be guaranteed for a wide range of plastic materials. Due to its polymer structure, plastic material generally tends to allow radon diffusion and hence radon loss from the sample resulting in a disturbance of the required decay equilibrium. The paper introduces an approach that allows quantifying radon loss from sample capsules by direct radon measurements using mobile radon detection equipment. The experimental findings are supported by theoretical considerations. An examined alternative approach based on the offset of the 186.2 keV data point from an efficiency function that is calculated exclusively from short-lived radon progeny peaks in the gamma-ray spectrum did not prove to be applicable due to a lack of supporting peaks in the low-energy section of the spectrum.

A novel simplified method is presented for the estimation of the metabolism of plasma proteins (albumin, fibrinogen, α, β and γ-globulin, glycoprotein) with regard to the whole body protein metabolism in a young male volunteer (22 years, 81 kg body mass). This method is based on multiple oral administration of [¹⁵N]glycine followed by measurement of ¹⁵N in plasma proteins, total free amino acids, urea and excreted urinary N. The fractional synthesis rate of albumin was estimated to 6.8 % d^-1 based on amino acids and 3.3 % d^-1 based on urea, respectively. The fractional synthesis rate of the other plasma proteins ranged from 4.3 % d^-1 (γ-globulin) to 26.4 % d^-1 (α-globulin, fibrinogen). We conclude that the simplified approach using [¹⁵N]glycine provides results which are similar to results based on the simultaneously applied ¹³¹I-human serum albumin technique as 'gold standard' and to those reported in literature. The compartmental analysis considering comprehensive tracer kinetic data ensures reliable data treatment and enables statistical evaluation. The analytical effort is minimal because the ¹⁵N enrichment of plasma protein after chemical digestion may be directly used. Therefore, the novel stable isotope ¹⁵N method is suitable for studies in clinical and nutritional research and practice.

This study assessed radon (²²²Rn) levels in drinking water sources in the Nizampur basin and their potential health risks for the local community. We analyzed 48 water samples on-site using RAD7. Additionally, we measured pH, temperature (T), total dissolved solids (TDS), redox potential (ORP), and electrical conductivity (EC) with a multiparameter analyzer. Results showed pH, T, TDS, ORP, and EC ranging from 7.2 to 8, 17 to 26 °C, 333 to 1130 mg/l, -56 to 284 mV, and 469 to 2370 µS/cm. ²²²Rn levels varied significantly (0.7-107 Bq/l, mean 23 ± 21, median = 17 Bq/l), with about 65 % exceeding the EPA's limit of 11.1 Bq/l, indicating health risks likely due to local geological conditions. The annual effective doses for ingestion (Ew_Ing) were 0.87 ± 0.01, 0.35 ± 0.006, and 0.13 ± 0.002 µSv/a for adults, infants, and children, respectively. Exposure risk via the inhalation (Ew_Inh) route ranged from 1.75 to 270 µSv/a, with the highest risk in infants, followed by children and adults. Inhalation was the primary exposure route for all age groups. Further, spatial distribution maps and hotspot analysis suggested that the central region characterized by high structural deformation and favorable geology for radon emanation was the area of concern in terms of health risks.

Stable isotope (δ²H, δ¹³C) measurements of wing tissue have been used to determine the natal geographic origin of migrant monarch butterflies that overwinter in Mexico. This study examines the possibility of using δ¹³C and δ¹⁵N to identify the milkweed habitat used by monarchs in their natal region. Milkweeds were common in corn and soybean fields before herbicide use led to their extirpation around 2006, and the loss of those milkweeds has been proposed as a reason for the monarch population decline. If crop-field monarchs can be identified, then historical samples of monarchs could be examined to test that hypothesis. The δ¹⁵N and δ¹³C values of leaves from milkweeds growing in corn fields, soybean fields and non-agricultural habitats were examined as well as monarchs that were raised on those leaves. There were no δ¹⁵N values for leaves or monarchs that were distinctive for crop fields. Milkweeds in corn fields, and monarchs that were raised on those milkweeds, were found to have δ¹³C values distinctly lower than those of other habitats and unlike those of locations within the summer breeding range. Thus, it should be possible to identify monarchs that came from cornfields in samples of overwintering monarchs made before ca. 2006.

It is known that the oxygen isotope composition of CO₂-in-air, when stored over longer time periods in glass sample flasks, tends to drift to more negative values while the carbon isotope composition remains stable. The exact mechanisms behind this drift were still unclear. New experimental results reveal that water already inside the flasks during sampling plays a major role in the drift of the oxygen isotopes. A drying method to remove any water sticking to the inner walls by evacuating the flasks for more than 72 h while heating to 60 °C significantly decreases drift of the oxygen isotopes. Moreover, flasks not dried with this method showed higher differences among drift rates of individual flasks. This is explained through the buildup of H₂O molecules sticking to the inner walls. Humidity of the air samples in the flasks as well as surface characteristics will lead to differences among flasks. Results also show that permeability of water is higher through Viton O-ring flask seals than through polychlorotrifluoroethylene (PCTFE) shaft seals, and that the stability of flasks sealed with the latter is significantly better over time.

Strandings of striped dolphins (SD) and short-finned pilot whales (PW) in Hokkaido, northern Japan, are rare but have recently increased, probably due to global warming. We quantified δ¹³C, δ¹⁵N, and δ¹⁸O in muscles of SD (n = 7) and PW (n = 3) stranded in Hokkaido and compared these values with those in muscles (red meat products) of hunted SD and PW in three areas of central and southern Japan. δ¹⁸O in stranded SD, except for the calf, decreased with increasing body length (BL), whereas δ¹³C increased, with no BL-related changes in δ¹⁵N. The variability of δ¹⁸O (range of maximum and minimum) was larger in the stranded SD (7.5 ‰) than of the hunted SD in three areas (0.9, 1.9, and 1.4 ‰), whereas that of δ¹⁵N was smaller in the stranded SD than in the hunted SD. Similarly, the variability of δ¹⁸O was larger in the stranded PW in Hokkaido (3.3 ‰) than in the hunted PW in central Japan (1.4 ‰). The larger variability of δ¹⁸O and smaller variability of δ¹⁵N in stranded SD imply long-term sojourning in coastal waters and feeding on small amounts of limited prey species at low trophic levels before death.