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排序方式: 共有268条查询结果,搜索用时 31 毫秒
51.
三峡库区大宁河流域非点源污染研究 总被引:3,自引:0,他引:3
以大宁河流域巫溪水文站控制流域为研究对象,应用分布式非点源污染模型SWAT,利用实测流量、泥沙负荷及氮、磷负荷数据对模型进行了率定和验证,并模拟了大宁河流域的径流量和营养物质氮、磷的排放.结果表明,月平均流量在率定期和验证期的效率系数分别达到了0.93和0.62;泥沙负荷的效率系数分别为0.70和0.34;氨氮和总磷的效率系数分别达到了0.31和0.37.大宁河流域污染物质的排放存在着较大的空间差异,有机氮和有机磷的5年平均排放量区间分别为2.01~38.15和0.35~5.89 ks/(hm2·a),其中,流域西南部子流域的有机氮和有机磷平均排放量最大,分别为38.15和5.89 ks/(hm2·a),是大宁河流域污染物排放的最敏感区域. 相似文献
52.
Yao Z Wang Q He K Huo H Ma Y Zhang Q 《Journal of the Air & Waste Management Association (1995)》2007,57(11):1379-1386
On-board emission measurements were performed on 49 light-duty gasoline vehicles in seven cities of China. Vehicle-specific power mode distribution and emission characteristics were analyzed based on the data collected. The results of our study show that there were significant differences in different types of roads. The emission factors and fuel consumption rates on arterial roads and residential roads were approximately 1.4-2 times those on freeways. The carbon monoxide, hydrocarbon, and nitrogen oxides emission factors of Euro II vehicles were on average 86.2, 88.2, and 64.5% lower than those of carburetor vehicles, respectively. The new vehicle emission standards implemented in China had played an important role in reducing individual vehicle emissions. More comprehensive measures need to be considered to reduce the total amount of emissions from vehicles. 相似文献
53.
镁渣配料煅烧硅酸盐水泥熟料的研究 总被引:8,自引:0,他引:8
研究了镁渣矿物组成和镁渣配料煅烧硅酸盐水泥熟料的反应动力在数和物理性能。结果表明:镁渣的主要矿物组成为γ-C2S、β-C2S、MgO、CF、C2F、FeO、CaF2等,并且镁渣可降低熟料形成反应表观活化能,加速熟料矿物的形成,提高熟料的强度。 相似文献
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55.
通过对仪化涤纶厂乙醛废气污染源的调查及监测,分析了其源强、生产车间及厂区内外的分布规律,并进一步作了该厂乙醛废气对环境影响的预测评价。结果表明,周边地区乙醛废气的质量浓度分布均达到《工业企业设汁卫生标准》的要求。 相似文献
56.
成瘾者头发样品中滥用药物的GC—MS鉴定 总被引:2,自引:0,他引:2
本文采用气相色谱-质谱方法分离、鉴定成瘾者头发样品中的滥用药物,样品处理方法简单,甲醇一次超声提取,提取效果较好,样品用量少,仅需20mg。应用该法对几例成瘾者头发样品进行了分析鉴定,不公检出几种代谢产物,而且检出药物的原形。 相似文献
57.
AQI(Air Quality Index,空气质量指数)是一套目前在国际上被广泛应用的大气环境质量评价体系,本文采用这一体系对呼和浩特市的空气质量进行了评价。根据2003年的监测数据,分析了本市2003年的大气环境现状及季节变化趋势;利用1990-2003年14年间的空气中污染物年均值,分析了本市大气环境质量的年际变化趋势。其结论为:呼和浩特市空气的主要污染因子为TSP,而且空气质量虽在逐渐好转,但仍然基本处于“不健康”的状态,因此,需要政府继续采取措施进一步改善。 相似文献
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59.
Shouliang Huo Chunzi M Beidou Xi Yali Zhang Fengchang Wu Hongliang Liu 《环境科学学报(英文版)》2018,30(5):54-66
Nutrient criteria provide a scientific foundation for the comprehensive evaluation, prevention,control and management of water eutrophication. In this review, the literature was examined to systematically evaluate the benefits, drawbacks, and applications of statistical analysis,paleolimnological reconstruction, stressor-response model, and model inference approaches for nutrient criteria determination. The developments and challenges in the determination of nutrient criteria in lakes and reservoirs are presented. Reference lakes can reflect the original states of lakes, but reference sites are often unavailable. Using the paleolimnological reconstruction method, it is often difficult to reconstruct the historical nutrient conditions of shallow lakes in which the sediments are easily disturbed. The model inference approach requires sufficient data to identify the appropriate equations and characterize a waterbody or group of waterbodies, thereby increasing the difficulty of establishing nutrient criteria. The stressor-response model is a potential development direction for nutrient criteria determination, and the mechanisms of stressor-response models should be studied further. Based on studies of the relationships among water ecological criteria, eutrophication, nutrient criteria and plankton, methods for determining nutrient criteria should be closely integrated with water management requirements. 相似文献
60.
To perform a systematic survey on the occurrence and removal of micropollutants during municipal wastewater treatment, 943 semi-volatile organic chemicals in 32 wastewater samples including influents of secondary treatments, secondary effluents and final effluents(effluents of advanced treatments), which were collected from seven full-scale municipal wastewater treatment plants(MWTPs) in China, were examined by gas chromatography-mass spectrometry(GC-MS) coupled with an automated identification and quantification system with a database(AIQS-DB). In total, 196 and 145 chemicals were detected in secondary and final effluents, respectively. The majority of the total concentrations(average removal efficiency, 87.0%±5.9%) of the micropollutants were removed during secondary treatments. However, advanced treatments achieved different micropollutant removal extents from secondary effluents depending on the different treatment processes employed. Highly variable removal efficiencies of total concentrations(32.7%–99.3%) were observed among the different advanced processes. Among them,ozonation-based processes could remove 70.0%–80.9% of the total concentrations of studied micropollutants. The potentially harmful micropollutants, based on their detection frequency and concentration in secondary and final effluents, were polycyclic aromatic hydrocarbons(PAHs)(2-methylnaphthalene, fluoranthene, pyrene, naphthalene and phenanthrene), phosphorus flame retardants(tributyl phosphate(TBP), tris(2-chloroethyl)phosphate(TCEP) and tris(1,3-dichloro-2-propyl) phosphate(TDCP)), phthalates(bis(2-ethylhexyl)phthalate(DEHP)), benzothiazoles(benzothiazole,2-(methylthio)-benzothiazol, and 2(3H)-benzothiazolone) and phenol. This study indicated that the presence of considerable amounts of micropollutants in secondary effluent creates the need for suitable advanced treatment before their reuse. 相似文献