念青唐古拉山沼泽土壤微生物群落和酶活性随海拔变化特征

选取青藏高原念青唐古拉山地处不同海拔的高寒沼泽土壤作为研究对象,测定土壤理化指标以及土壤酚氧化酶、脲酶、过氧化物酶、蛋白酶、L-天冬酰胺酶和碱性磷酸酶活性,提取土壤微生物磷脂脂肪酸量,得到土壤微生物生物量,研究沼泽土壤微生物群落和土壤酶活性随着海拔增加的变化特征,探讨土壤微生物群落和土壤酶活性与环境因子之间的关系。结果表明,高寒沼泽土壤理化指标、土壤酶活性和土壤微生物量都随海拔增加而明显减小。相关分析与典范对应分析结果显示,年平均气温与大多数土壤物理化学指标、土壤酶活性和土壤微生物量显著正相关。年平均气温是影响念青唐古拉山地区高寒沼泽生态系统土壤微生物群落结构和土壤酶活性变化的重要因子。     

Investigation of mechanisms of formation of biphenyls and benzonaphthothiophenes by simulation experiment

The formation mechanisms of biphenyl series and benzonaphthothiophene series are investigated by means of simulation experiment. Biphenyl series are likely formed in two ways: one is the aromatization of the chain compounds containing conjugated C== C double bonds or the compounds with such a kind of sidechains, and the other is the reaction of sulfur with ordinary chain compounds, in which sulphur acts on ordinary sidechain compounds by seizing some hydrogens and forming (H2S and) the intermediates with conjugated C== C double bonds first, and then the intermediates are aromatized. One of the basic precursors of benzonaphthothiophenes is likely the phenylnaphthalenes which may originate from the chain compounds containing conjugated C== C double bonds, the compounds with such sidechains and saturate or unsaturate chain compounds. Thermal stability of biphenyls is high, but they can become dibenzothiophenes and polycyclic aromatic hydrocarbons or dibenzofurans and polycyclic aromatic hydrocarbons respectively in the presence of sulphur or oxygen. The ratio of biphenyl and m-biphenyl to biphenyls may be employed to indicate the depositional environment in the mild to medium maturation, of which the higher value indicates a fresh water depositional environment and the lower indicates a saline depositional environment. The relative high content of benzonaphthothiophenes in the crude oil indicates that the crude oil has undergone an intense sulfurization in the source rock or reservoir.     

Oxidant-elemental sulfur as an effective promoter for transformation of organic matter to hydrocarbons at moderate-low temperatures

Elemental sulfur is widely dispersed in the hydrocarbon source rocks and its depositional environment is usually thought as a reducing environment. The presence or absence of free oxygen is a key to identify oxidizing or reducing environment. But elemental sulfur is often present as an oxidant in this environment. When elemental sulfur meets with organic matter, redox reaction will occur. In our simulation experiments at 200 -400℃ , the existence of elemental sulfur can sharply increase the amounts of hydrocarbons, hence leading to the production of immature or low-mature oils and natural gases. At the temperature of 300℃ , the addition of elemental sulfur will further enhance the relative yields of hydrocarbons,and the final yield of total extracts and gaseous hydrocarbons of similitude kerogens by more than 463% and 2760% , respectively, while those of oil shales are increased by about 71% and 2044% , respectively. But at the temperature of 450℃, elemental sulfur plays a negative role in liquid hydrocarbon formation. The presence of elemental sulfur is probably a key factor in the gypsolyte environment leading to the formation of immature or low-mature oils, as well as the coexistence of immature or low-mature oils and natural gases.