Oil viscosity from experiments and model calculations

Five frequently-used models were chosen and evaluated to calculate the viscosity of the mixed oil. Totally twenty mixed oil samples were prepared with different ratios of light to crude oil from different oil wells but the same oil field. The viscosities of the mixtures under the same shear rates of 10 s**-1 were measured using a rotation viscometer at the temperatures ranging from 30°C to 120°C. After comparing all of the experimental data with the corresponding model values, the best one of the five models for this oil field was determined. Using the experimental data, one model with a better accuracy than the existing models was developed to calculate the viscosity of mixed oils. Another model was derived to predict the viscosity of mixed oils at different temperatures and different values of mixing ratio of light to heavy oil.

(Table) Radiocarbon datings of sediment core BLK-1 obtained from Barkol Lake, China

The Barkol Lake, as a closed inland lake, is located at the northeast Xinjiang in northwest China. A combination of geochemical indicators including d18O and d13C of carbonate, TOC, carbonate contents, as well as grain size proxies and magnetic susceptibility of sediments obtained from a newly recovered section at this lake, provides a high-resolution history of climatic change in the past 9400 years. Multi-indicators reflect that Holocene climatic change in the study region generally follows the Westerly Wind pattern of Holocene, and three climatic periods can be identified. Between 9400 and 7500 cal a B.P., climate was characterized by relatively drier and colder condition. From 7500 to 5800 cal a B.P., a relatively warmer and moister climate prevailed, but between 5800 and 3500 cal a B.P., climate shifted towards warmer and drier conditions. A relatively colder and wetter climate prevailed during 3500~1000 cal a B.P., then it changed towards cold and dry between 1000 and 500 cal a B.P.; after 500 cal a B.P., climate changed towards warm and dry conditions again. This study reflects that during the Middle Holocene (from ca 7000 to 3500 cal a B.P.), variations of carbonate d18O of sediments from several lakes in the northern Xinjiang were synchronous with that of Qinghai Lake, where was strongly influenced by the South Asian monsoon; however, after 3500 cal a B.P. this consistency was interrupted, possibly resulting from a re-domination of the Westerly Wind and the retreat of South Asian monsoon in the northern Xinjiang.

Bomb-tritium input function calculated from the details of the nuclear atmospheric bomb tests released by the UNSCEAR [2000]

Improving the representation of the hydrological cycle in Atmospheric General Circulation Models (AGCMs) is one of the main challenges in modeling the Earth's climate system. One way to evaluate model performance is to simulate the transport of water isotopes. Among those available, tritium (HTO) is an extremely valuable tracer, because its content in the different reservoirs involved in the water cycle (stratosphere, troposphere, ocean) varies by order of magnitude. Previous work incorporated natural tritium into LMDZ-iso, a version of the LMDZ general circulation model enhanced by water isotope diagnostics. Here for the first time, the anthropogenic tritium injected by each of the atmospheric nuclear-bomb tests between 1945 and 1980 has been first estimated and further implemented in the model; it creates an opportunity to evaluate certain aspects of LDMZ over several decades by following the bomb-tritium transient signal through the hydrological cycle. Simulations of tritium in water vapor and precipitation for the period 1950-2008, with both natural and anthropogenic components, are presented in this study. LMDZ-iso satisfactorily reproduces the general shape of the temporal evolution of tritium. However, LMDZ-iso simulates too high a bomb-tritium peak followed by too strong a decrease of tritium in precipitation. The too diffusive vertical advection in AGCMs crucially affects the residence time of tritium in the stratosphere. This insight into model performance demonstrates that the implementation of tritium in an AGCM provides a new and valuable test of the modeled atmospheric transport, complementing water stable isotope modeling.