固相反射散射分光光度法测定化妆品中的铅

在酸性条件下 ,铅 ( )与玫瑰红酸钠形成紫红色络合物沉淀 ,该沉淀能被均匀地抽滤到一定表面积的滤纸上。本文采用固相反射散射分光光度法直接测定滤纸上负载的络合物的反射吸收值 AR,铅的含量在 0～ 8μg/ m L的范围内 AR与浓度有良好的线性关系。方法简便、快速 ,检出限为 0 .0 5μg/ m L。相对标准偏差为3.0 %。方法用于化妆品中铅的测定 ,结果令人满意     

几种新型光催化水质净化反应器的探讨

综述了几种新型光催化反应器的结构、特征，讨论各反应器的应用情况和处理效果，对其优缺点进行评价。指出光催化技术与其它成熟水处理技术的耦合是光催化工艺进入实际应用的重要途径。     

青海省塔拉滩草原利用方向探讨

青海省共和县塔拉滩是一个平坦开阔的大草原，近４０多年来一直有宜农与宜牧之争。本文就此，从３个方面作了重点论述：垦滩种粮的后果严重；超载过牧也有潜在生态危机；最佳出路是将根治沙源与合理利用草原结合起来，发展季节畜牧业，走一条治用结合、滩谷互补、农牧业相互促进的道路，建设一个新型草原。     

共沉淀富集—固相光度法快速测定微量汞

以Cu2 I2 与Cu2 HgI4 共沉淀法富集微量汞 ,采用固相反射散射分光光度法测定沉淀物中微量汞的含量。探讨了该方法的基本原理 ,选择了最佳的反应条件和测定条件。该法具有快速、简便、灵敏等优点 ,可应用于极谱实验室空气中、土壤、水体及植物体中微量汞的测定。     

Influence of surfactant-facilitated interfacial tension reduction on chlorinated solvent migration in porous media: observations and numerical simulation

The ability of a multiphase flow model to capture the migration behavior of chlorinated solvents under conditions of surfactant-facilitated interfacial tension (IFT) reduction is assessed through comparison of model predictions with observations from controlled laboratory experiments. Tetrachloroethene (PCE) was released in two-dimensional saturated systems, packed with sandy media that incorporated rectangular lenses of capillary contrast. Spatially uniform interfacial tension conditions were created in the tanks by pre-flushing the porous medium with either Milli Q water or an aqueous surfactant solution. Experimental observations showed that surfactant-facilitated IFT reductions substantially lowered capillary resistance to the vertical downward migration of PCE and enabled PCE to enter finer grained, less permeable lenses that were not penetrated in the absence of surfactant. An immiscible flow model was used to simulate the conditions of the laboratory experiments. Under higher IFT conditions (47.5 and 5 dyn/cm), the model could successfully predict the general migration behavior of the organic liquid. Model predictions, however, exhibited poorer agreement with observed migration pathways under low IFT conditions (0.5 dyn/cm). In all cases, the predicted PCE distributions were influenced by selection of the parametric model for capillary retention and relative permeability. Simulated migration rates were more consistent with observed behavior when the Brooks-Corey/Burdine model was employed. For low interfacial tensions, improved predictions of migration pathways were obtained through grid refinement and incorporation of small-scale packing variability. Simulations highlight the substantial sensitivity of model predictions to the capillary pressure-scaling factor, grid resolution, and small-scale porosity variations at interfaces of permeability contrast under reduced IFT conditions.     

Simple screening models of NAPL dissolution in the subsurface

Three simple screening models of nonaqueous phase liquid (NAPL) dissolution in the subsurface are proposed based on the NAPL mass conservation and the assumption of proportionality between the residual NAPL source zone concentration and the remaining residual NAPL mass. The purpose of the proposed models is to predict the solute concentration in the zone of the residual NAPL as a result of dissolution. The predicted source zone concentration decrease is used to simulate and account for the decrease of dissolution rate with time. The proposed simple NAPL dissolution models enable the pseudo-equilibrium formulation to be used and therefore the numerical simulations for field application problems can be simplified compared to the non-equilibrium counterpart. With proper choice of empirical parameters, the proposed simple screening models can work as well as more complex dissolution rate correlation models, such as that of Imhoff et al. [Water Resour. Res. 30 (1994) 307-320]. It is found that the proposed models are very good for quantifying non-equilibrium dissolution, which is characterized by tailing of breakthrough curves. The models are especially useful for situations of small residual NAPL saturation, which are typical for many field applications.     

Residual gasoline saturation in unsaturated soil with and without organic matter

The goal of this study was to investigate the influence of one variable, natural organic matter, on residual gasoline saturation in sandy soils. Capillary pressure-saturation (P_c−S) relationships (air-gasoline) were determined for three physically-similar sandy soils, with different organic carbon contents (0.086%, 0.89% and 1.65%) and residual gasoline saturations were compared. Two initial moisture conditions, residual water saturation and air-dry, were evaluated. One soil type was packed to two different bulk densities. Visualization of the soils using cryo-scanning electron microscopy was performed to aid in better understanding the role of the organic matter in the soil. The results showed that soils with higher organic contents had higher residual gasoline saturations when starting with an initially air-dry soil. Increasing the bulk density of the same air-dried soil resulted in an increase in residual gasoline saturation. In the presence of a residual water saturation, however, residual gasoline saturations were virtually identical for the three soils and independent of bulk density; approximately 5–10 times lower than in soil that was initially air-dry. The presence of the residual water effectively coated the surface of the soil thereby reducing or eliminating gasoline/soil interactions. Some residual water may also be occupying very small pore spaces, making these locations inaccessible to the gasoline.     

Infiltration and redistribution of LNAPL into unsaturated layered porous media

Enhanced understanding of light non-aqueous phase liquid (LNAPL) infiltration into heterogeneous porous media is important for the effective design of remediation strategies. We used a 2-D experimental facility that allows for visual observation of LNAPL contours in order to study LNAPL redistribution in a layered porous medium. The layers are situated in the unsaturated zone near the watertable and they are inclined to be able to observe the effect of discontinuities in capillary forces and relative permeabilities. Two experiments were performed. The first experiment consisted of LNAPL infiltration into a fine sand matrix with a coarse sand layer, and the second experiment consisted of a coarse sand matrix and a fine sand layer. The numerical multi-phase flow model STOMP was validated with regard to the experimental results. This model is able to adequately reproduce the experimental LNAPL contours. Numerical sensitivity analysis was also performed. The capillarity contrast between sands was found to be the main controlling factor determining the final LNAPL distribution.     

三相生物流化床处理生活废水

对三相生物流化床处理生活废水进行了实验研究，探讨了生物载体种类、溶解氧、水力停留时间及供气量对处理效果的影响。在选择的实验条件下，对进水CODcr值为600～1700mg／L的选定废水样，CODCr的平均去除率为85．8％。     

新型固相萃取器用于污染水样中痕量杀虫剂的浓缩及热解吸气相色谱-质谱分析

1　IntroductionSolid phasemicro extraction (SPME)asasimpleandrapidextractiontechniqueiswidelyusedinvariousareasforextractingdiluteanalytesfromliquid ,gaseousandsolidsamplesbecauseofitshighextractionefficiency[1 ].Recently ,astirbarsorptiveextraction (SBSE…