Geoscience

Major Biogenic Elements in South Yellow Sea

Recently, the research project on the balance and evolution process of important biogenic elements in the South Yellow Sea completed by Dr. Song Jinming and other researchers from the Institute of Oceanology, CAS.

The results established an analytical approach for the patterns of inorganic carbon in offshore sediments, improved the in-situ simple and direct method for determining seawater DIC (dissolved inorganic carbon). It was found that Jiaozhou Bay was a source of atmospheric CO2 in spring, summer and autumn, whereas it was a weak sink in winter. In dry season, the Yangtze River estuary gradually transited from strong source of atmospheric CO2 in low salinity zone to weak source in high salinity zone, whereas it was a net source of atmospheric CO2 in high water season. This revealed the strength and control process of carbon sources and sinks in South Yellow Sea. The simulation showed that nutrient salts and heavy metals have major impact on the strength of carbon sources and sinks in sea. It revealed different patterns of inorganic carbon in sediments and its contribution to carbon cycle in sea and concluded that hydrochloric acid-phase in sediments might be one of final patterns of atmospheric CO2. It elaborated the biogeochemical characteristics and ecological environmental significance of nitrogen and phosphate in sediments from Jiaozhou Bay and revealed the evolution process of sedimentary environment in Jiaozhou Bay. The results of this research have so far produced 47 papers (including 19 SCI or EI papers) and a monograph.

Contribution of Alpine Meadow Ecosystem to Global Change

On Dec. 28, 2008, the research on “The Relationship between Alpine Meadow Ecosystem and Global Change” accomplished by the Northwest Institute of Plateau Biology, CAS. Response of species to light and response of community structure and pasture grass quality to temperature increment in alpine meadow ecosystem were studied using the methods of intensified field ultraviolet radiation and experimental warming. It revealed that alpine meadow plants have strong adaptive capacity to strong ultraviolet radiation and light; temperature increment can reduce the species diversity of alpine meadow plants and nutritional quality of pasture grass on Tibetan Plateau and proper grazing can reduce the negative effects on diversity loss caused by temperature increment. Using eddy covariance method, it confirmed for the first time that the alpine meadow on the Tibetan Plateau has strong carbon sink capacity. Its carbon-capturing capacity is limited by soil carbon storage and interference of grazing, while proper use of natural meadow can improve carbon sequestration of ecosystem. It was found for the first time that herbaceous plant on alpine meadow releases methane and woody plant potentilla truticosa assimilates methane. This provides new evidence for the emission of methane on alpine meadow area. Through research on the response of alpine meadow to human activities and climatic change, it confirmed that alpine meadow ecosystem has strong restorability and stability and put forward the hypothesis of passive-active retrogression on retrogressive succession of alpine Kobresia meadow, which provides important theoretical basis for the restoration and management of degraded alpine meadow and sustainable management of ecosystem.