Temporal and spatial variations of atmospheric methane concentration and δ13 C-CH4 near the surface on the Millor Peninsula, East Antarctica

During the 22nd Chinese Antarctic Research Expedition (CHINARE222, 2005/06) , the atmospheric gas samples near the surface were taken on the Millor Peninsula and adjacent areas, east Antarctica, using Tedlar gas bags. The methane(CH4) concentration and δ13 C-CH4 in those samples were analyzed in the laboratory. The average value of atmospheric CH4 concentration on this peninsula was (1.87 ± 0.12) × 10(-6) , slightly higher than the global average CH4 concentration. The summertime variation of CH4 concentrations showed a large fluctuation, corresponding to the variation of air temperatures. The average δ13 C-CH4 was ( -38.26 ± 0.52) ‰. CH4 concentrations and δ13 C-CH4 at different sites varied from 1.74 × 10(-6) to 2.56 ×10(-6) and from -39.31‰ to - 31.25‰, respectively. The factors affecting CH4 concentrations and δ13 C-CH4 values have also been discussed in this study

Alkaline phosphatase activity in ornithogenic soils in polar tundra

Phosphatase plays an important role in the microbial liberation of phosphorus in soil systems. In this study, alkaline phosphatase activity (APA) was investigated from tundra ornithogenic soil profiles in Antarctica and Arctic. The organic carbon (TOC), total nitrogen (TN), and phosphorus fractions and pH were also analyzed in these soils. The correlation between APA and soil chemical properties is discussed. In almost all the soil profiles, APA showed the same variation patterns. The maximum APA appeared in the surface layers, and decreased with soil depth. The APA ranged from 1.00 ppm to 1 403.5 ppm with an average of approximately 408.3 ppm. The APA showed a significant positive correlation with TOC (r =0.70, p <0.001), TN (r =0.43, p =0.002), total phosphorus (r =0.39, p <0.05)and inorganic phosphorus (r =0.40, p =0.037), indicating that they were predominant factors affecting APA in the polar tundra soils. In addition, APA showed a significant negative correlation with Cu and Zn concentrations in the soils, indicating that Cu and Zn may inhibit APA. Our results showed that APA could be used as an important indicator for soil fertility in polar tundra ecosystems

Ecological responses of typical Antarctic marine organisms to climate change and anthropogenic impacts

To improve our understanding and ability to predict biological responses to global climate change, it is important to be able to distinguish the influences of natural forcing from anthropogenic impacts. In the ice-free areas of Antarctica, lake and terrestrial sediments that contain penguin guanos, seal excrement and other biological remains provide natural archives of ecological, geological and climatic information that range from hundreds to thousands of years old. Our review focuses on the paleoecology of typical Antarctic marine organisms (penguins, seals and Antarctic krill) and their responses to climate change and human activities over centennial and millennial timescales. Land-based seabirds and marine mammals play an important role in linking the marine and terrestrial ecosystems and act as bio-vectors, transporting large amounts of nutrients and contaminants from ocean to land

Association of Monosodium Glutamate Intake With Overweight in Chinese Adults: The INTERMAP Study

Animal studies indicate that monosodium glutamate (MSG) can induce hypothalamic lesions and leptin resistance, possibly influencing energy balance, leading to overweight. This study examines the association between MSG intake and overweight in the human species. We conducted a cross-sectional study of 752 healthy Chinese (48.7% women), ages 40 to 59 years, randomly sampled from three rural villages in north and south China. The great majority of participants prepared their foods at home, without use of commercially processed foods. Diet was assessed with four in-depth multi-pass 24-hour recalls. Participants were asked to demonstrate MSG amounts added in food preparation. Amounts shaken out were weighed by trained interviewers. Overweight was defined as body mass index ≥25.0 kg/m2 or ≥23.0 (based on World Health Organization recommendations for Asian populations). Eighty-two percent of participants used MSG. Average intake was 0.33 gram/day (standard deviation=0.40). With adjustment for potential confounders including physical activity and total energy intake, MSG intake was positively related to body mass index. Prevalence of overweight was significantly higher in MSG users than non-users. For users in the highest tertile of MSG intake compared to non-users, the multivariable-adjusted odds ratios of overweight (body mass index ≥23.0 and ≥25.0) were 2.10 (95% CI, 1.13–3.90, P for trend across four MSG categories=0.03) and 2.75 (95% CI, 1.28–5.95, P=0.04). This research provides human data that MSG intake may be associated with increased risk of overweight independent of physical activity and total energy intake

The identification and comparison of the bio-elements of the penguin ornithogenic sediments sample from Davis Station and Great Wall Station

During CHINARE-22 in austral summer of 2005-2006, a lake sediment core named DG4, which is impacted by penguin droppings, was retrieved from a lake catchment in Gardner Island of Vestfold Hills, East Antarctica. In this study, the concentrations of characteristic elements in the core, local bedrocks and fresh penguin guanos were determined. P, Se, F, S, As, Sr and Cu in DG4 were identified as the bio-element assemblage by R-clustering analysis and compared with those in the local bedrocks and fresh guanos, the results are similar to Y2 in Ardley Island, Antarctic Peninsula. On this basis, P and Se were identified as the optimum bio-elements in DG4 and F, P and S were identified in Y2, respectively. This work will provide the foundation for reconstructing the past penguin populations in Gardner Island of Vestfold Hills, East Antarctica and comparing the penguin population dynamics between East Antarctica and Antarctic Peninsula

Atmospheric nitrous oxide observations above the oceanic surface during the first Chinese Arctic Research Expedition

339 gas samples above oceanic surface were collected on the cruise of "Xuelong" expeditionary ship and nitrous oxide concentrations were analyzed in the laboratory. Results showed that Atmospheric average N2O concentration was 309 ± 3. 8nL/L above the surface of northern Pacific and Arctic ocean. N2O concentrations were significantly different on the northbound and southbound track in the range of the same tatitude, 308.0 ± 3.5 nL/L from Shanghai harbor to the Arctic and 311.9 ± 2.5 nL/L from the Arctic to Shanghai harbor. N2O concentration had a greater changing magnitude on the mid and high-latitude oceanic surface of northern Pacific Ocean than in the other latitudinal ranges. The correlation between the concentrations of the compositions in the aerosol samples and atmospheric N2O showed that continental sources had a great contribution on atmospheric N2O concentration above the oceanic surface. Atmospheric N2O concentration significantly increased when the expeditionary ship approached Shanghai harbor. The average N2O concentrations were 315.1 ± 2.5 nL/L, 307.2 ± 1.4 nL/L and 306.2 ± 0.7 nL/L, respectively, at Shanghai harbor, at ice stations and at floating ices. The distribution of N2O concentrations was related with air pressure and temperature above the mid and high-latitude Pacific Ocea