XCOOH(X=F,Cl,Br)热分解反应的理论研究

用密度泛函理论(DFT)B3LYP方法,在6 311 G 基组水平上,计算了反应XCOOH(X=F,Cl,Br)HX CO2.优化了反应物 中间体 过渡态和产物的几何构型,并用频率分析和内禀坐标法(IRC)验证了各鞍点构型和反应路径,计算了不同温度(200 15～450 15K)下慢反应经零点能校正的活化热力学量、反应过程热力学改变量、正逆反应的速率常数和频率因子以及平衡常数,得到了各反应的动力学信息.     

华南黑色岩系铂多金属矿成矿流体地球化学及其矿床成因意义

较系统的流体包裹体观测显示:①华南黑色岩系铂多金属矿中存在两种不同体系的流体包裹体,一为具中低盐度、NaCl-H2O体系者(Ⅰ型);二为具中高盐度、CaCl2-NaCl-H2O体系者(Ⅱ型);其中后者为该类矿床中首次确定;②存在2个不同期次的成矿流体,其中铂多金属矿层和其下伏磷块岩中碳酸盐石英网脉的流体包裹体特征基本一致,可能代表主成矿期流体,其均一温度峰值为170℃左右,而盐度具双峰式特征,峰值分别为27%～31%和4%～6%;矿层之上碳酸盐石英脉中流体包裹体可能代表了晚期成矿流体,其均一温度多为130～170℃左右,盐度峰值在12%～14%;③在早寒武世,接受了巨厚沉积的扬子克拉通南缘加里东冒地槽中的盆地热卤水受挤压而顺层侧向迁移,从地层中汲取Ni、Mo、V和PGE等成矿元素,形成中高盐度的CaCl2-NaCl-H2O体系成矿热液,沿断裂上升并与NaCl-H2O体系海水混合,形成黑色岩系中的铂多金属矿床(点).     

Analysis of carbon isotopes in airborne carbonate and implications for aeolian sources

Methods were developed to determine the mass ratios of carbon isotopes in trace amounts of aerosol carbonate. A Finnigan MAT 252 mass spectrometer fitted with an on-line Kiel device was to determine the ^13C/^12C ratio in CO2 produced from the carbonate. A study using these methods was conducted to characterize the carbonate carbon isotopes in aerosol samples collected in Xi‘an on dusty and normal days during March and April 2002. Results of the study demonstrate that insights into the origin of the dust can be deduced from its isotopic composition. That is, the δ^13C ofcarbonate for dust storm samples ranged from -1.4‰ to -4.2‰, and this is consistent with sandy materials in dust source regions upwind. In contrast, for non-dusty days δ^13C ranged from -7.5% to -9.3‰, which is more similar to fine particles emitted from local surface soils. Comparisons of dust storm aerosols with surface soils from source regions and with aerosol samples collected downwind indicate that the δ^13C values did not change appreciably during longrange transport. Therefore, carbon isotopes have the potential for distinguishing among source materials, and this approach provides a powerful new tool for identifying dust provenance.     

Deep-water Earliest Oligocene Glacial Maximum （EOGM） in South Atlantic

The most prominent cooling event of the Earth surface during Cenozoic in the long-term transition from a non-glaciated planet, or “green-house world”, to a polar, glaciated planet, or “ice-house world”, is the Earliest Oligocene Glacial Maximum (EOGM) above the Eocene/Oligocene boundary at about 33.7 Ma. Planktonic and benthic foraminiferal oxygen and carbon isotopes, carbonate content, and coarse fraction, along with high-resolution color reflectance and magnetic susceptibility records during 35-30 Ma, from deep-water Sites 1262 and 1265, Ocean Drilling Program (ODP) Leg 208 in South Atlantic, reveal the global cooling event occurring in both surface and deep oceans. The results show that the earliest Oligocene δ^18O values during 33.5-33.1 Ma represent the magnitude of continental ice sheets on east Antarctica and indicate the large decrease in both surface and deep water temperatures of worldwideoceans. The δ^13C records show the large excursion during the period of EOGM event and indicate some types of shift in global carbon reservoir, probably demonstrating the sudden increase in organic carbon burial rates and the changes in the distribution and timing of production. At the same time, lithologic composition, carbonate content, color reflectance, and coarse fraction brought about significant changes close to the Eocene/Oligocene boundary, reflecting the abrupt deepening in the carbonate compensation depth (CCD). Changes in carbonate content were revealed from the color reflectance identify periodicities associated with eccentricity of the Earth‘s orbit (100 and 400 ka), further indicating orbitally forced global climate variations in the Early Oligocene.     

西秦岭中生代花岗岩锆石U-Pb-Lu-Hf同位素特征及地质意义

对西秦岭地区中川岩体、柏家庄岩体和教场坝花岗岩体进行LA-ICP-MS锆石U-Pb同位素年代学分析, 获得其岩浆侵位年龄分别为220±1, 216±6和222±3 Ma, 表明3个岩体均形成于中?晚三叠世。样品的全岩地球化学分析结果表明, 3个岩体具有相似的稀土及微量元素特征, 均表现为显著亏损高场强元素Nb, Ti和P等, 具有明显的右倾式球粒陨石标准化稀土元素配分模式。锆石Lu-Hf同位素分析结果表明, 3个岩体锆石测年样品的ε_Hf(t)值介于?3.31~+1.68之间, 二阶段模式年龄介于1151~1456 Ma之间。岩石成因分析表明, 这些印支期花岗岩体的母岩浆主要来源于新元古代地壳物质的部分熔融。结合岩体形成时代、岩石成因和区域岩浆作用, 认为这些岩体形成于南秦岭与华南板块沿勉略缝合带相碰撞的造山动力学背景, 可能与华南板块的俯冲板片断离有关。     

[bmim]Zn_2Cl_5/NH_3溶液的比热容和过量焓

测定了离子液体[bmim]Zn_2Cl_5在T=(323.15~1 173.15)K范围内的热重曲线,结果显示[bmim]Zn_2Cl_5在T637.15 K时具有很高的热稳定性。通过DSC测试得到[bmim]Zn_2Cl_5的比热容数据,在T=(251.15~383.15)K范围内可以用一个圆锥曲线很好地拟合。实验测定了[bmim]Zn_2Cl_5(2)+NH3(1)二元体系溶液的摩尔过量焓,其中氨的摩尔分数x1=(0.60~0.95),温度值为T=288.15 K,303.15 K,318.15 K,333.15 K。采用NRTL模型对过量焓数据进行拟合,得出二元可调参数和非随机参数。过量焓数据的测量误差和最大拟合偏差分别小于4.8%和4.3%。在[bmim]Zn_2Cl_5比热容和[bmim]Zn_2Cl_5/NH3过量焓数据的基础上,计算了氨质量分数w1=(0~1)、温度范围T=(273.15~343.15)K条件下[bmim]Zn_2Cl_5/NH3溶液的焓,所得焓浓图对于研究[bmim]Zn_2Cl_5/NH3吸收式制冷系统性能至关重要。     

离子液体中纤维素的溶解及再生特性

探讨了不同来源纤维素在离子液体1-丁基-3-甲基咪唑氯代盐(［bmim］Cl)中的溶解性能,并采用红外光谱、X-射线衍射及热重分析等手段对木浆纤维素在离子液体［bmim］Cl中溶解和再生前后的结构变化进行了分析。结果表明,未经活化的纤维素可直接溶解于离子液体［bmim］Cl 而不发生其它衍生化反应,原纤维素聚合度越低,溶解越容易。再生纤维素分子量较原纤维素有所降低,结晶状态由纤维素Ⅰ转变为纤维素Ⅱ,再生后纤维素热分解温度降低,热稳定性略有下降。     

Carbon and hydrogen isotopic compositions and their evolutions of gases generated by herbaceous swamp peat at different thermal maturity stages

Coalbed methane (CBM) accumulation models include continuous gas accumulation and staged gas accumulation.However,studied on the geochemical characteristics and indices to evaluate staged accumulation CBM are lacking.This study for the first time obtained the carbon and hydrogen isotopic compositions of methane and ethane generated at different evolution stages using thermal simulation of samples prepared by treating an herbaceous swamp peat at different temperatures.The results showed that the carbon isotopic compositions of methane and ethane were obviously affected by the thermal evolution level of the starting sample,while the hydrogen isotopic compositions were closely related to the maturity of gases.The carbon and hydrogen isotopic compositions of gases generated by coal-forming organic matter with Ro values from 1.2%,1.7%,2.4%,3.2% and 3.7% to 5.2% were determinated.The relationship between Ro values and the carbon and hydrogen isotopic compositions of gases generated by coal-forming organic matter at different evolution stages as well as the carbon or hydrogen isotopic relationships between methane and ethane were established.The results provide a scientific basis for studying the genesis of CBM generated at different maturity intervals and understanding the geochemical characteristics of staged accumulation CBM.These results were applied to a case study on CBM from the southern Qinshui basin,and it was found that the CBM accumulated after the Middle Jurassic and was characteristic of staged gas accumulation.This is consistent with the result of geological studies,and further showed that the results of thermal simulation experiments are very important for evaluating the genesis of natural CBM.     

Potential influence of water level changes on energy flows in a lake food web

Large seasonal water-level fluctuations may influence isotopic signatures of primary producers and the types and amounts of these potential food sources accessible to aquatic fauna of Poyang Lake,the largest freshwater lake in China.In this study,the isotopic signatures of primary producers and consumers were determined,stable carbon and nitrogen isotope analysis and mixing models were combined to investigate the influence of water levels on the diet and isotopic composition of Poyang Lake fish and inverteb...     

川东北宋家洞石笋氧碳同位素周期分析

对采自川东北宋家洞的石笋SJ3的氧碳同位素值进行了小波分析和REDFIT分析,得到以下结果:(1)氧同位素值在18.3～17.5 ka有显著的174 a的周期,碳同位素值在16.2～15.4ka、18.3～17.8ka有显著的174 a的周期;(2)氧碳同位素值的周期与太阳活动周期有关。这些表明石笋记录在短时间尺度上与太阳活动存在显著关联。