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排序方式: 共有1492条查询结果,搜索用时 31 毫秒
911.
污染物在水体中的扩散规律研究已引起越来越多人的关注。通过现场扩散示踪实验求得扩散系数,进而对污染物的扩散规律予以定量描述,是一种可靠易行的方法。对黄河托克托至河曲段的实际研究表明,以Cr2O或F-为示踪剂,运用Taylor模型进行多沙大河的污染物扩散规律研究可以取得满意的结果。同时,利用现场示踪实验结果与经验公式的结合可以预测不同情况下的纵向扩散系数,从而得出污染物的允许排放量,这将有利于污染物在水体中行为的深入研究。  相似文献   
912.
A generalized quantitative risk assessment for the use of source-segregated green waste (SSGW) compost use in livestock production is presented. This assessment focussed on potential risks associated with a specific product, PAS100 compost that meets the UK publicly available specification 100 and represents the majority of compost available for use in extensive Scottish livestock systems. A hazard screening approach was used to identify all potentially hazardous agents present in compost. A total of 497 potentially hazardous agents were screened, with 147 finally put forward for quantitative risk assessment. Scenarios modelled in the assessment included surface application of compost to grazing land and also incorporation into soil and subsequent uptake by fodder crops. Risk estimates were compared to those associated with six comparator materials, including various sludges, slurries and farm yard manures. Overall, five potentially hazardous agents (PCB28, PCB138, PCB153, 1,2,3,4,6,7,8-HpCDD, Clopyralid) returned a hazard quotient >1 but within margins of uncertainty, indicating that further investigation may be required. Within the limitations of available information, SSGW compost was found to pose less risk to grazing livestock, or the environment, than other commonly-used soil amendments. While this assessment relates to a specific product/standard used in the UK, the methodology could easily be applied to other composts/products/situations. Therefore these results have wider applicability.  相似文献   
913.
Clay minerals modified with organic ions, also known as organoclays, have found applications in a wide range of organic pollution control fields because of their excellent sorption capacity towards organic pollutants. Regeneration of the spent organoclays after the sorption of organic pollutants is of great importance during their application in pollution control. In this review, the reported methods for the regeneration of the spent organoclays are summarized, including biological degradation, photo-assisted oxidation, chemical extraction/desorption, supercritical extraction, thermal desorption, et al. The characteristics and applications of these methods are briefly described. It shows that most of these methods have been developed for regenerating spent organoclays from wastewater treatment. The biological regeneration method, as an in situ, low cost and easy-operating method, is applicable for regenerating spent organoclays not only from wastewater treatment, but also from soil and groundwater remediation.  相似文献   
914.
We evaluated the suitability of single and multiple cell type cultures as model systems to characterise cellular kinetics of highly lipophilic compounds with potential ecotoxicological impact. Confluent mono-layers of human skin fibroblasts, rat astrocytoma C6 cells, non-differentiated and differentiated mouse 3T3 cells were kept in culture medium supplemented with 10% foetal calf serum. For competitive uptake experiments up to four different cell types, grown on glass sectors, were exposed for 3 h to 14C-labelled model compounds, dissolved either in organic solvents or incorporated into unilamellar lecithin liposomes. Bromo-, or chloro-benzenes, decabromodiphenylether (DBP), and dichlorodiphenyl ethylene (DDE) were tested in rather high concentration of 20 μM. Cellular toxicity was low. Compound levels were related to protein, DNA, and triglyceride contents. Cellular uptake was fast and dependent on physico-chemical properties of the compounds (lipophilicity, molecular size), formulation, and cell type. Mono-halogenated benzenes showed low and similar uptake levels (= low accumulation compounds). DBP and DDE showed much higher cellular accumulations (= high accumulation compounds) except for DBP in 3T3 cells. Uptake from liposomal formulations was mostly higher than if compounds were dissolved in organic solvents. The extent of uptake correlated with the cellular content of triglycerides, except for DBP. Uptake competition between different cell types was studied in a sectorial multi-cell culture model. For low accumulation compounds negligible differences were found among C6 cells and fibroblasts. Uptake of DDE was slightly and that of DBP highly increased in fibroblasts. Well-defined cell culture systems, especially the sectorial model, are appropriate to screen for bioaccumulation and cytotoxicity of (unknown) chemical entities in vitro.  相似文献   
915.
- DOI: http://dx.doi.org/10.1065/espr2006.01.011 Goal, Scope and Background Chile signed the Stockholm Convention, which establishes measures to reduce or eliminate Persistent Organic Pollutants (POPs) release into the environment, including the prohibition of their use and reduction of secondary products release, as well as management related with waste treatment. Among POPs, PCBs are a family of 209 compounds that differ in chlorine level and position. These substances present a wide variability in their physicochemical properties such as vapor pressure, water solubility and partition coefficients that determine their behavior and mobility within the different environmental compartments. In Chile, as in other countries, the use of these compounds were and continue to occur in diverse industrial applications such as dielectric fluid in transformers and condensers, with a use in Chile of approximately 550,000 L. A sampling of bivalves was performed during the years 2000-2002 in order to obtain information on the spatial distribution of the PCB levels for the length of the long Chilean coast (180–540 South latitude, 4,200 km), contributing in this way to a better understanding of the PCB trend and eventual fractionation along latitudinal gradients in Chile, using as the bivalve Perumytilus purpuratus ('Chorito Maico') bioindicator. Methods The marine bivalves Perumytilus purpuratus were collected in 16 localities in northern and southern Chile. All samples were lyophilized, and PCBs (51 congeners) were extracted in a Soxhlet system (24 h) with n-hexane. Samples were cleaned in florisil and analyzed by GC-ECD. Blanks, certified reference materials and standards were processed along with the samples. Results and Discussion The results obtained for P. purpuratus indicate a congeneric distribution profile associated to a latitudinal gradient, and the statistical analysis of the congeneric composition of the PCBs indicated five groups in relation to the molecular weight (number of chlorines), where the lighter congeners were observed in areas corresponding to high latitudes with total PCB values of 298 ng/g dry weight. Conclusion P. purpuratus turns out to be a good bioindicator of PCB levels in the coastal areas of Chile due to its wide distribution. The highest concentrations and the more volatile congeners were found in southern Chile, which could be the result of processes of long-range transport or illegal discharge occurring in such remote areas. These results confirm previous data from the International Mussel Watch project ten years ago. Recommendation and Outlook Future studies are needed to confirm our findings utilizing another environmental matrix such as soil/sediments and air samples.  相似文献   
916.
臭氧多相催化氧化处理微污染水中试研究   总被引:5,自引:1,他引:4  
通过中试系统初步比较了非均相催化剂催化臭氧化与传统中间臭氧化在饮用水深度处理中的净化效能.结果表明,对有机物污染宏观指标CODMn、TOC的控制,催化臭氧化具有明显优势,降低了后续处理工艺的有机物负荷;催化臭氧化与中间臭氧化对UV254的去除率相当;催化剂能够强化臭氧氧化,使其进一步去除水中持久性有毒有害有机物,并且显著地提高了臭氧氧化氨氮生成硝酸盐氮的能力,催化剂也强化了臭氧的传质与利用.  相似文献   
917.
Abstract

The traditional evaluation of energy consumption mostly introduces pollutants as a negative economic output into evaluating model, ignoring the configuration relationship among the energy input, pollutants as well as economic output. This paper considers the overall process of energy consumption and constructs an evaluation indication system of energy consumption level combined with endogenous pollutants based on entropytopsis method, then makes empirical research. The results show that China’s energy consumption level presents a fluctuant rise in the premise of emission. Energy consumption level depends on the relationship among energy input, pollutants and economic output. The raise of energy consumption level should not increase economic output and reduce pollutant emission at the expense of environment. Finally, the whole paper puts forward the countermeasures to improve the overall level of energy consumption.  相似文献   
918.
武汉城市住宅室内空气质量现状调查与研究   总被引:1,自引:0,他引:1  
通过对武汉城市住宅室内装修情况及室内空气质量的调查,反映了武汉城市住宅室内装修的总体特征及室内空气质量的现状,探讨了室内装修影响室内空气质量的主要因素。  相似文献   
919.
实验从锦州石化长期被高浓度的烃类化合物污染的土壤中采取土样,经反复富集培养后分离得到降解原油的单一菌株X2,并对菌株X2生长条件进行了优化,其优化后的最佳生长条件为:温度30℃,pH值为7,恒温摇床转速为190 r/min,盐度为2.5%。同时,实验利用最佳条件下培养获得的对数生长期降解菌X2降解处理含原油1.0%的无机培养液,经过24 h处理,测得降解菌X2对原油的降解能力达到60.6%。  相似文献   
920.
江苏省作为我国的经济大省,对其进行环境持久性药物污染物(EPPPs)的污染特征与生态风险评估研究很有必要.本研究以江苏省1~4级河流和面积≥50 km2的湖泊为研究目标,对EPPPs的污染现状进行检测和分析.结果表明,江苏省地表水中共检出35种EPPPs,浓度范围为66.74~2189.83 ng·L-1;该研究主要对检出率大于25%的17种EPPPs进行了探讨,其浓度水平为72.48~1142.79 ng·L-1,浓度均值为345.20 ng·L-1.EPPPs总浓度水平苏北和苏南浓度水平高于苏中地区.其中扬州市EPPPs浓度全省最高,可能主要污染来源为生活污水、航运污水排放及渔业养殖中的药物使用.EPPPs总浓度整体以京杭运河、废黄河为中线向两侧递减.对17种EPPPs的生态风险评估表明,单一目标药物对江苏省水生态风险较小;采用简单叠加模型计算出的联合毒性风险商范围为0.03~0.52,联合毒性对水生生物表现为低至中等风险.  相似文献   
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