Spatial variation in mercury concentrations in polar bear (Ursus maritimus) hair from the Norwegian and Russian Arctic.

We examined spatial variation in total mercury (THg) concentrations in 100 hair samples collected between 2008 and 2016 from 87 polar bears (Ursus maritimus) from the Norwegian (Svalbard Archipelago, western Barents Sea) and Russian Arctic (Kara Sea, Laptev Sea, and Chukchi Sea). We used latitude and longitude of home range centroid for the Norwegian bears and capture position for the Russian bears to account for the locality. We additionally examined hair stable isotope values of carbon (δ13C) and nitrogen (δ15N) to investigate feeding habits and their possible effect on THg concentrations. Median THg levels in polar bears from the Norwegian Arctic (1.99 µg g-1 dry weight) and the three Russian Arctic regions (1.33-1.75 µg g-1 dry weight) constituted about 25-50% of levels typically reported for the Greenlandic or North American populations. Total Hg concentrations in the Norwegian bears increased with intake of marine and higher trophic prey, while δ13C and δ15N did not explain variation in THg concentrations in the Russian bears. Total Hg levels were higher in northwest compared to southeast Svalbard. δ13C and δ15N values did not show any spatial pattern in the Norwegian Arctic. Total Hg concentrations adjusted for feeding ecology showed similar spatial trends as the measured concentrations. In contrast, within the Russian Arctic, THg levels were rather uniformly distributed, whereas δ13C values increased towards the east and south. The results indicate that Hg exposure in Norwegian and Russian polar bears is at the lower end of the pan-Arctic spectrum, and its spatial variation in the Norwegian and Russian Arctic is not driven by the feeding ecology of polar bears.

New on-line methods for determining the deuterium/hydrogen composition of water and hydrocarbon gases using O(2-) ion-conducting solid electrolyte reactor.

RATIONALE: The deuterium/hydrogen (D/H) composition of water and hydrocarbon gases is widely used in geological, environmental and petroleum studies. The aim of this work was to develop a simple reduction zirconium dioxide solid electrolyte reactor (SER) for water decomposition and new methods for measuring hydrogen isotope ratios in water and hydrocarbon gases. METHODS: δ(2)H(VSMOW) values were determined using two new different on-line methods: solid electrolyte reactor isotope ratio mass spectrometry (SER-IRMS) for water and gas chromatography combustion solid electrolyte reactor isotope ratio mass spectrometry (GC-C-SER-IRMS) for hydrocarbon gases. RESULTS: We have designed a solid electrolyte reactor based on oxygen ion-conducting zirconium dioxide stabilized by yttria (Y(2)O(3)). The reactor was used for catalytic electrochemical decomposition of water in a helium carrier gas. The solid electrolyte reactor has a small internal volume of 0.1 cm(3). It was operated at a temperature of ~950 °C. The total time of analysis for determining the hydrogen isotope ratio in water was 150 s. A typical water sample volume was about 0.2 µL (split ratio 500:1). The precision of the δ(2) H(VSMOW) measurements for water was better than or equal to 2.2‰ and that for hydrocarbon gases was within 0.5-3.0‰. CONCLUSIONS: Fast, simple and accurate on-line methods (SER-IRMS and GC-C-SER-IRMS) were developed. The SER-IRMS method makes it possible to work with small water samples. Although the GC-C-SER-IRMS method was developed for hydrocarbons, it can also be used for other organic gases and their mixtures. The new solid electrolyte reactor for water decomposition is low cost and the ceramic tube is inexpensive.

On the application of a ZrO2-based solid electrolyte in isotope ratio mass spectrometry.

The application of a high-temperature electrochemical reactor based on stabilized zirconium dioxide (0.9 ZrO(2)0.1 Y(2)O(3)) for organic gas sampling in continuous-flow isotope-ratio mass spectrometry (CF-IRMS) has been found to be efficient. This solid electrolyte reactor (SER) can also be used as a chromatographic detector for the quantitative measurements of organic gases. A three-electrode SER system was studied. Complete stoichiometric oxidation of organic gases has been achieved at 900-950 degrees C due to the large catalytic surface area of the porous platinum coating. At this temperature, the oxygen ions formed from the oxygen of ambient air on the outer surface of the reactor migrate through the solid electrolyte under the action of the applied electric field and allow combustion of gases being analyzed to be effected. It should be noted that oxygen gas was not introduced into the gas-carrier flow. Similar results for the measurements of carbon isotope ratios were obtained at the oxidation of hydrocarbon gases in both the standard and the solid electrolyte reactors.