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991.
W. Scott Hall Kenneth L. Dickson Farida Y. Saleh John H. Rodgers Douglas Wilcox Azam Entazami 《Journal of the American Water Resources Association》1986,22(6):913-920
ABSTRACT: Current procedures for setting site-specific water quality criteria consider abiotic and biotic factors. Suspended solids were shown to be important in reducing zinc toxicity to water column organisms. At zinc concentrations of ~ 1 mg/L in solutions with < 100 mg/L of all suspended solids tested, zinc toxicity to D. magna was reduced. Sorption of zinc to suspended solids and/or changes in water chemistry due to the addition of suspended solids appear to have been the factors causing reductions in zinc toxicity to D. magna. Only suspended solids levels of 483–734 mg/L of a type that increased total alkalinity, total hardness, and total dissolved carbon clearly reduced the toxicity of ~ 20 mg/L zinc to P. promelas. The toxic form of zinc to these organisms appears to reside in the aqueous phase. Characteristics of suspended solids did not influence the partition coefficient of zinc in sorption experiments of 96 h. The slopes of dose-response curves proved to be useful for assessing the potential of an organism to respond to changes in aqueous phase zinc concentrations, and may be a useful biological parameter when considering site-specific water quality criteria for chemicals. 相似文献
992.
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
993.
994.
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
995.
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
996.
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
997.
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
998.
999.
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
1000.
基于SPSS聚类分析的企业职业伤害风险分级标准研究 总被引:1,自引:2,他引:1
对不同行业和不同规模的221家企业基础数据的调研分析,借助sPSS的聚类分析功能,对企业职业伤害风险分级进行研究,通过综合分析认为将企业职业伤害风险分为4类较为合理,并给出了企业职业伤害风险分级建议标准。根据该标准对在广西壮族自治区A市和辽宁省B市调研获取的661家企业职业伤害风险进行分级分析,从而验证分级标准的合理性和可行性。 相似文献