Forms and functions of inorganic carbon in the Jiaozhou Bay sediments

Inorganic carbon forms and their influencing factors, mutual transformation and contribution to carbon cycling in the Jiaozhou Bay sediments were discussed. The results show that inorganic carbon in sediments could be divided into five forms: NaCl form, NH3 center dot H2O form, NaOH form, NH2OH center dot HCl form and HCl form. Thereinto, NH2OH center dot HCl form and HCl form account for more than 70% of total inorganic carbon. There was close relationship among every form of inorganic carbon and their correlativity was clearly different with different sedimentary environment except the similar strong positive correlation among NH2OH center dot HCl form, HCl form and total inorganic carbon in all regions of the Jiaozhou Bay. All forms of inorganic carbon were influenced by organic carbon, pH, Eh, Es, nitrogen and phosphorus in sediments, but their influence had different characteristics in different regions. Every farm of inorganic carbon transformed into each other continuously during early diagenesis of sediments and the common phenomenon was that NaCl form, NH3 center dot H2O form, NaOH form and NH2OH center dot HCl form might transform into steady HCl form. NaCl form, NH3 center dot H2O form, NaOH form and NH2OH center dot HCl form could participate in carbon recycle and they are potential carbon source; HCl form may be buried for a long time in sediments, and it may be one of the final resting places of atmospheric CO2. Inorganic carbon which entered into sediments was about 4.98 x 10(10) g in the Jiaozhou Bay every year, in which about 1.47x10(10) g of inorganic carbon might be buried for a long time and about 3.51. x 10(10) g of inorganic carbon might return into seawater and take part in carbon recycling.

A Simulative Study on Effects of Climate Warming on Nutrient Contents and In Vitro Digestibility of Herbage Grown in Qinghai-Xizang Plateau

The increasing trend of air temperature along with the climate warming has been accepted gradual-ly by scientists and by the general public. Qinghai-Xizang Plateau, a unique geographic unit due to high-altitude climate, is one of the most susceptible regions to climate warming. Its ecosystem is very fragile and sensi-tive to climate change. In order to get a better understanding of the impacts of climate warming on the nutrient contents of herbage grown in Qinghai-Xizang Plateau, a simulative study was implemented at Daban Moutain by using temperature differences resulted from sites selected at different altitudes and nutrient contents and in vitro digestibility were determined for assessing the quality of the grown herbage. There were significant downtrends in crude protein (CP), ether extract (EE) and nitrogen free extract (NFE) contents of herbage along with the increase of temperature. It had a positive correlation between temperature and content of acid detergent fibre (ADF), acid detergent lignin (ADL) in herbage. In vitro digestibility of herbage decreased along with the in-crease of temperature. The results of this study indicated that climate warming significantly influence nutrient contents and in vitro digestibility of herbage grown in Qinghai-Xizang Plateau. It is suggested that the future climate warming especially the gradual rise of the night temperature could cause negative effect on herbage quality grown in Qinghai-Xizang Plateau by decreasing CP, EE, and NFE contents and increasing some indi-gestible ingredients such as crude fibre (CF), neutral detergent fibre (NDF), ADF, and ADL. This, conse-quently, decreases the ruminant assimilation ability.

南海天然气水合物地热学研究

Through generalizing the thermal field characteristics in gas hydrates distribution area in the world, the favorable thermal conditions for gas hydrates in the South China Sea are analyzed firstly. On the basis of above analysis, focused on the gas hydrates stability zone (GHSZ), the dissertation initiated the gas hydrates studies with geothermal methods in the South China Sea which will provide useful information for gas hydrates resource exploration and evaluation in the future. On the basis of study on hydrates phase equilibrium and the GHSZ affecting factors, the potential planar distribution of gas hydrates is determined by studying the temperature and pressure conditions in the sea bottom with different water depth, and the thickness of GHSZ is attained by solving the hydrates phase boundary curve equation and geothermal gradient curve equation. The result shows that, if the chemical composition of hydrocarbons contains methane only and the salt content of water is 3.5%, hydrates can form and keep stable at sea bottom at water depth not less than 550m, and the thickness of GHSZ is more than 200m in Xisha Through, Southeastern area of Dongsha Islands, Southwestern basin of Taiwan Island, northern area of Nansha Trough. The GHSZ is thicker with heat flow, geothermal gradient, and thermal conductivity decreasing, and with water depth increasing. Geothermal field simulating also attains the base of GHSZ in Xisha through, which is less than the depth of BSR. Although the present T-P conditions is not the most favorable for gas hydrates through 6Ma history, gas hydrates are still profitable in Xisha Through, Southeastern area of Dongsha Islands, Southwestern basin of Taiwan Island, Luzon Trough and northern area of Nansha Trough by systemic study on the sedimentary and structural characteristics, the conditions of T-P and natural gas source, considering geochemical and geophysical indications found in the South China Sea.