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821.
正辛醇/水分配系数的测定及估算方法 总被引:1,自引:0,他引:1
介绍了正辛醇/水分配系数的测定和估算方法。将现有的测定方法分成直接法和间接测定法进行了介绍和评价。直接法主要介绍了摇瓶法、两相滴定法和萃取法;间接法主要介绍了产生柱法和色谱法。给出了不同测定方法的使用范围及其局限性。在估算方法介绍中,将现有的辛醇/水分配系数的估算方法按其对溶质的处理方法不同分为两大类进行了介绍,一类是以整个分子为研究对象的分子法,如摩尔体积法;另一类是根据分子的结构信息进行估算的结构性能法,如分子连接性指数法,基因贡献法。介绍了现有基团贡献法如Leo碎片常数法、Meylan和Howard的AFC基因贡献法、三水平基团贡献法、基团贡献溶剂化模型法、UNIFAC基团贡献法的优缺点及其使用局限性。提出了估算方法的发展方向。 相似文献
822.
ABSTRACT: The longitudinal dispersion of tracer material in rivers is simulated by a dead-zone model that involves two coupled differential equations. For an instantaneous injection of tracer material, the problem is solved by the Laplace. Transform and numerical inversion to obtain the time-concentration curve at any sampling station. The optimal values of the model parameters are estimated from field measurements. Applications of the model to three different rivers generally show that the model reproduces the longitudinal dispersion characteristics in natural streams with sufficient accuracy. 相似文献
823.
本文根据(环境科学概论)的水质基本方程,对江水分段水质管理提出数学模型,用线性规划和最优化方法提出控制江水污染的决策措施,我们可以根据这些数据有计划地提出治理方案,使江水水质符合国家标准,同时使资金投入最省。 相似文献
824.
825.
回归反射材料光度测试探讨 总被引:1,自引:0,他引:1
本文根据回归反射材料所特有的反光性能,对其三种测试方法及可能出现的影响测试结果的因素进行了分析讨论,为测试系统的设计、测试方法和仪器的选择及测试结果的不确定度评估提供参考。 相似文献
826.
油气生产危险源的评价方法研究 总被引:1,自引:3,他引:1
针对油气生产危险源的种种特性和规律,运用HSE管理体系的核心理念和管理原则,对生产场所从高能量物质的性质和状态进行分类和确定,记录其所在地点、数量、性质、流向或扩散方向和周围环境,形成一个危险源集合;组织相关专家和机构,对该集合进行系统分析、科学评价;制定风险控制措施和风险削减措施并记录在案,适时实施以求风险最小。该方法的一些作法已在大庆油田等诸多油气生产企业使用且行之有效。 相似文献
827.
An attempt was made to judge the environmental compatibility, the governing leaching mechanism, and mobility patterns in a
waste–cement solidified/stabilized matrix after 21 days of curing. The mixed sludge from a steel pickling facility was stabilized
by ordinary Portland cement. Iron was the major leachable metal, along with Pb, Zn, and Mn. To characterize the leaching behavior,
the mobility and mechanism of leaching were determined by diffusion leaching tests. In the solidified/stabilized matrix, the
mobility of all the elements studied was reduced, and average to low mobility was observed. Values for the negative log of
the effective diffusion coefficient of more than 12.5 were obtained for the metals. The dominant leaching mechanisms were
surface wash off in the initial stage, followed by diffusion. The environmental performance of the solidified/stabilized product
when considered in terms of mass leached over 64 days was found to be satisfactory for consideration for the safe disposal
and reuse of waste. 相似文献
828.
Marcel van der Perk Philip N. Owens Lynda K. Deeks Barry G. Rawlins 《Water, Air, & Soil Pollution: Focus》2006,6(5-6):443-451
A spatially extensive geochemical data set of stream water and bed sediment composition across the Tamar catchment in south-west
England was analysed to identify the key bed sediment properties that control the in-stream dissolved reactive phosphorus
(DRP) concentrations during baseflow conditions. Linear regression analysis of the streamwater DRP concentrations and the
distribution coefficient K
d for DRP revealed that the former is positively correlated with total SiO2 and Al2O3, and negatively correlated with K2O. The primary control on these major element distributions is the dominant bedrock geology. The data suggest that streamwater
DRP concentrations are mainly controlled by adsorption to clay minerals. Where P concentrations in streamwater were considerably
elevated by inputs from point sources, DRP concentrations are also controlled by precipitation of hydroxyapatite. 相似文献
829.
830.
ABSTRACT: The Soil and Water Assessment Tool (SWAT) has been used for hydrologic analyses at various watershed scales. However, little is known about the model's performance in coastal watersheds. In this study SWAT was evaluated for its applicability in three Louisiana coastal watersheds: the Amite, Tickfaw, and Tangipahoa River watersheds. The model was calibrated with daily discharge from 1976 to 1977 and validated from 1979 to 1999 for the Amite and Tangipahoa and with daily discharge from 1979 to 1989 for the Tickfaw. Deviation of mean discharge and the Nash‐Sutcliffe model efficiency were used to evaluate model behavior. The study found that Manning's roughness coefficient for the main channel, SCS curve number, and soil evaporation compensation factor were the most sensitive parameters for these coastal watersheds. The Manning's roughness coefficient showed the greatest effect on the response time of surface runoff, suggesting the critical role of channel routing in hydrologic modeling for lowland watersheds. The SWAT model demonstrated an excellent performance, with Nash‐Sutcliffe efficiencies of 0.935, 0.940, and 0.960 for calibrations of the Amite, Tickfaw, and Tangipahoa watersheds, respectively, and of 0.851, 0.811, and 0.867 for validations. The modeling results demonstrate that SWAT is capable of simulating hydrologic processes for medium scale to large scale coastal lowland watersheds in Louisiana. 相似文献