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901.
902.
903.
A novel method for assaying and calculating the toxicity of water-insoluble pesticides to green algae has been put forward in this work. First, a solvent is selected for use in bioassays; there should be a detailed screening to identify a solvent with inherently low toxicity to the test organism. Second, the EC50 is determined for selected pesticides by measuring the toxicity of various concentrations of each of the selected pesticides in a fixed concentration of selected solvent. Third, concentrations of the selected solvent are varied and the EC50 of each pesticide tested is assayed at a fixed concentration. Fourth, several suitable groups of solvent concentrations are selected and the corresponding EC50 values of tested pesticides are considered to establish the linear regression equation. Letting the solvent concentration be zero, one calculates the corresponding EC50 value, which corresponds to the inherent toxicity of the tested pesticide. 相似文献
904.
Zhou Xiaoxiao Chen Siyu Zhang Hua 《Environmental science and pollution research international》2023,30(1):501-514
Environmental Science and Pollution Research - Following a Chinese saying: To be rich, roads first, high-speed rail (HSR) opening and station construction are indispensable for economic developing.... 相似文献
905.
稠油污水处理系统改造与絮凝剂筛选试验研究 总被引:2,自引:1,他引:2
河南油田井楼稠油联合站含油污水中的污油和悬浮物含量较高,超过150mg/L。为此,对该处理系统进行了改造,并对絮凝剂的筛选进行了试验。结果表明:无机絮凝剂与有机絮凝剂联合作用,可对污水中所含有的污油和有机物杂质的悬浮物产生很好的絮凝沉降效果。加药浓度、加药顺序及沉降时间均对絮凝沉降效果有一定的影响。改造后的污水处理系统实现了污水达标回注,降低了无效回注费用。同时还回收了污油,降低了药剂成本,产生了十分明显的经济效益,每年节约成本约500万元。 相似文献
906.
907.
γ-BHC在稻田壤和水稻上有不同程度异构化为α、β、δ-BHC的趋势,但强度不大,其异构化程度随土壤的基本理化性状和水稻植株各部位的差异而不同。由此推在正常使用的情况下,γ-BHC不至于因其异构化而构成对农田土壤与水稻的污染危害。 相似文献
908.
Chao‐Hsien Liaw Liang‐Ching Chen 《Journal of the American Water Resources Association》2004,40(4):971-979
ABSTRACT: This work begins by defining rational water use, and then discusses important factors that most strongly influence it. A general model is then developed to enable factories to quantify the ratio of rational industrial water reuse based on the least cost method. The model is established to minimize the cost of water with reference to gross water use and three subsystems ‐ the intake, reuse, and discharge of industrial water. Discharge cost is determined using data from a 1997 survey of 38 factories, and reuse costs are ranked and expressed by a step function. The model is verified using data from a typical semiconductor factory in northern Taiwan's Hsinchu Science Based Industrial Park, whose effective rational water reuse ratio is about 38 percent. A sensitivity analysis shows that improving water reuse technology is the most important factor in determining the rational water reuse ratio, and the price of water is the second most important. When water costs over NT$30 (New Taiwan Dollar, US$1 = NT$34) per cubic meter, increasing reuse becomes significant. The model provides a step towards the scientific management of industrial water. 相似文献
909.
910.
Hongyu Liu Hu Zhang Shan Chen Dongbo Liu Hongmei Xia 《Journal of Polymers and the Environment》2006,14(4):419-426
An extracellular poly (β-hydroxybutyrate) (PHB) depolymerase was purified from a Penicillium sp. DS9701-09a by centrifugation, ultrafiltration, precipitation and gel filtration chromatography. The specific activity of the purified enzyme was 37.9-folds higher than that of the culture supernatant and the recovery yield was 11.8%. The PHB deploymerase molecular mass was 44.8 kDa from analysis of both Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Matrix-assisted laser desorption-time-of-flight (MALDI-TOF) mass spectrometer. The isoelectric point of 6.7 for the enzyme was determined by a two-dimensional electrophoresis. The optimum enzyme activity was observed at a temperature of 50 °C and pH 5.0. The apparent K
m of the enzyme was found to be 1.35 mg/mL. The PHB depolymerase consisted of 16 kinds of normal amino acids. The secondary structure of the enzyme was determined by CD spectrum. α-helix and β-turn were found to be 66% and 34% for the enzyme without ammonium sulphite. Chemical inhibition on the PHB depolymerase activity was examined and EDTA was found to have a significantly inhibitory effect. 相似文献