Geoscience

Large Amounts of Gas Methane in the Central Arctic Ocean Found

Recently, Sun Liguang, Xie Zhouqing and their colleagues, from the Institute of Polar Environment, University of Science and Technology of China, published online the paper “Sea ice in the Arctic Ocean: Role of shielding and consumption of methane” in Atmospheric Environment. The paper reports methane emissions for the first time in the central Arctic Ocean through in-site sampling and analysis, indicating considerable methane storage in this region. The Sea ice in Arctic Ocean may regulate atmospheric methane level by shielding methane emission from the ocean, and consumption of methane in the surface or interior of sea ice. This finding provides basic knowledge to scientific evaluation on the contribution of methane from the Arctic Ocean. The experiment was performed in the summer of 2010 during the Fourth Chinese National Arctic Research Expedition. Researchers determined the flux of methane using closed chamber technique and collected the gas sample by vacuum vials. When the sea ice is broken, methane is emitted significantly. The methane flux from the undersea ice water was estimated to be 0.56 mg·m-2·d-1 on average, relatively higher than that in other oceans, indicating considerable methane storage below sea ice, which could limit methane emission. In addition, negative fluxes were observed above sea ice, suggesting that there are methane absorption and consuming processes over the sea ice. “Methane-oxidizing bacteria, which can consume methane, may exist in sea ice, and/or, methane possibly can be consumed by photochemical oxidation in the surface of sea ice.” said He Xin, co-first author of the paper. This result implies that the reduction of sea ice in the Arctic Ocean will result in the increase of the atmospheric methane concentrations, which in turn will further accelerate the process of sea ice melting.

Climate and Environment Changes in Qinghai-Tibetan Plateau Since Last Glacial Maximum Discovered

The Last Glacial Maximum refers to the period, during which the coldest climate by the deep-sea oxygen isotope record 2 occurs with largest glacier and desert area globally. The literature on the periglacial landform, paleosol-loess-aeolian sand and lake sediment of Gonghe Basin in northeastern Qinghai–Tibetan plateau have been collected by the researchers from the Cold and Arid Environmental and Engineering Research Institute, CAS. The regional climate and environment were reconstructed by cross-correlation method and the corresponding driving mechanisms are also analyzed. Results show that: before 14 ka BP, 14C age or the 16 ka cal BP, the stratum consists of aeolian sand and loess, and the climate was cold and dry, with developed periglacial landform and the vegetation feature of arid desert or desert steppe; During the last Deglaciation period (14 ka BP, 14C age or 16 ka cal BP to the Younger Dryas event, abbreviated as the YD), the climate tended to be warm and wet with the lake level obviously increased and the paleosol developed. The warm and cold climate (the B?lling–Aller?d and the YD) was found, with the vegetation of desert steppe; Before 8.5 ka BP (14C age) in Holocene, the temperature and humidity increased with higher lake level and the paleosol is developed with the vegetation of desert steppe or the dry steppe; in 8.5-7.0 ka BP, the climate is cold and dry, corresponding to the 1st Neoglaciation in Holocene. The development of paleosol was interrupted and the aeolian sand was formed; in 7.0–3.0 ka BP, the optimum warm and humid degree was found but the millennial–centennial scale cold events (2nd Neoglaciation) also exist, with developed paleosol, higher lake level and dry steppe vegetation. The climate tended to be arid and cool (cold) since the 3.0 ka BP (14C ages). The primary driving force is the variation of external factors e.g., the solar radiation, and the induced interaction of different circles in earth system.