青藏高原中部水蒸发过程中的氧稳定同位素变化

作为青藏高原稳定同位素水文循环的一个重部分 ,1 998年夏首次在青藏高原中部的那曲和安多两地同时进行了水蒸发过程中氧稳定同位素变化观测研究 .模拟和实验结果都显示出了大气相对湿度对水蒸发过程中氧稳定同位素变化的显著影响 .模拟结果还显示剩余水中δ18O与剩余水比率呈指数关系 ,但实验分析结果表明 ,蒸发过程中剩余水中δ18O与剩余水比率更接近于线性关系 ,这种关系可以定量地表示出来 .从理论上与实验中都可以计算出不同相对湿度下蒸发分馏因子的大小 .并且实验结果与理论模拟结果较一致 .

Assessment of semi-empirical mass transfer correlations for pervaporation treatment of wastewater contaminated with chlorinated hydrocarbons

Assessment of mass transfer characteristics of pervaporation （PV） treatment of wastewater contaminated with chlorinated hydrocarbons is of great importance for water treatment plant operators conducting initial evaluation, process optimization, and process economics. While a membrane plays a central role in pervaporation processes and separation efficiency, the mass transfer in the liquid layer next to the membrane surface is of equal, if not greater importance. It is one of the few process parameters that can be adjusted in situ to manipulate the outcome of a pervaporation process. In this study, a bench scale pervaporation experiment of removing a common chlorinated hydrocarbon from water was carried out and the results of it were compared to the ones based on well-known semi-empirical correlations. The mass transfer coefficients from the experiments, ranging from 0.8× 10^-5-2.5× 10^-5 m/s under the operating conditions, are higher than those predicted by the correlation. The corresponding separation factors under varying flow velocities are determined to be between 310-950.

Effects of Spatial Information of Soil Physical Properties on Hydrological Modeling Based on a Distributed Hydrological Model

The spatial distribution of soil physical properties is essential for modeling and understanding hydrological processes. In this study, the different spatial information (the conventional soil types map-based spatial information (STMB) versus refined spatial information map (RSIM)) of soil physical properties, including field capacity, soil porosity and saturated hydraulic conductivity are used respectively as input data for Water Flow Model for Lake Catchment (WATLAC) to determine their effectiveness in simulating hydrological processes and to expound the effects on model performance in terms of estimating groundwater recharge, soil evaporation, runoff generation as well as partitioning of surface and subsurface water flow. The results show that: 1) the simulated stream flow hydrographs based on the STMB and RSIM soil data reproduce the observed hydrographs well. There is no significant increase in model accuracy as more precise soil physical properties information being used, but WATLAC model using the RSIM soil data could predict more runoff volume and reduce the relative runoff depth errors; 2) the groundwater recharges have a consistent trend for both cases, while the STMB soil data tend to produce higher groundwater recharges than the RSIM soil data. In addition, the spatial distribution of annual groundwater recharge is significantly affected by the spatial distribution of soil physical properties; 3) the soil evaporation simulated using the STMB and RSIM soil data are similar to each other, and the spatial distribution patterns are also insensitive to the spatial information of soil physical properties; and 4) although the different spatial information of soil physical properties does not cause apparent difference in overall stream flow, the partitioning of surface and subsurface water flow is distinct. The implications of this study are that the refined spatial information of soil physical properties does not necessarily contribute to a more accurate prediction of stream flow, and the selection of appropriate soil physical property data needs to consider the scale of watersheds and the level of accuracy required.

Experimental investigation and cost assessment of the salt production by solar assisted evaporation of saturated brine

The technical feasibility and economy of solar heat collection-forced evaporation process are the keys to its practicality,especially its application in strong brine treatment.The operation cost of applying solar collection in salt manufacturing through depth evaporation of brine has been studied.For Na^＋,K^＋,Mg^2＋//Cl^-,SO4^2--H2O salt–water system,most of the Na Cl and all of the Carnallite were separated.The operation cost reached the optimum when the heat collection and evaporation were controlled at 75 and 55℃,respectively.When the solar radiation amount was 19557 kJ·m^-2·d^-1,the solar collector area for producing Carnallite was about 34.27 m^2·（t salt）^-1,and the operation cost was 13 USD·（t salt）^-1.The energy consumption of salt manufacturing is at least 25%higher than that of natural evaporation.Regarding the economy,the solar assisted salt manufacturing process is recommended to be performed at a production scale of more than 20 tons per day.

Evaporating behaviors of water droplet on superhydrophobic surface

We investigated the dynamic evaporating behaviors of water droplet on superhydrophobic surfaces with micropillars.Our experimental data showed that receding contact angles of the water droplet increased with the decreasing of the scale of the micropillars during evaporation,even though the solid area fractions of the microstructured substrates remained constant.We also experimentally found that the critical contact diameters of the transition between the Cassie-Baxter and Wenzel states are affected not only by the geometrical parameters of the microstructures,but also by the initial volume of the water droplet.The measured critical pressure is consistent with the theoretical model,which validated the pressure-induced impalement mechanism for the wetting state transition.