Pollution survey of polycyclic aromatic hydrocarbons in surface water of Hangzhou, China

The concentrations of 10 polycyclic aromatic hydrocarbons (PAHs) were simultaneously measured for five times (July and November 1999–2002) in four water bodies of Hangzhou, China. To investigate possible sources of PAH contamination, sediments, soils, runoff water and atmospheric particles of the region were also analyzed for their PAH contents. The maximum levels of PAHs in the water bodies (34.4–67.7 μg/l) were found in July, while significantly lower PAH concentrations (4.7–15.3 μg/l) were measured in November. The contamination is substantial and it may have resulted in acute toxic effects on aquatic organisms. The measured PAH concentrations in sediments and soils (224–4222 ng/g), runoff water (8.3 μg/l) and air particles (2.3 μg/m³) are discussed in relation to concentrations and patterns found in the surface water bodies. Comparison of PAH levels in sediments and soils led to the conclusion that the erosion of soil material does not contribute significantly to the contamination of sediments. The atmospheric PAH deposition to water bodies in the city area of Hangzhou was estimated to be 530 tons/a, while the contribution of surface runoff water was estimated to be 30.7 tons/a. The ratios of selected PAH were then used to illuminate the possible origin of PAHs in the examined samples (petrogenic, pyrogenic).     

Estimation and validation of PM2.5/PM10 exhaust and non-exhaust emission factors for practical street pollution modelling

In order to carry out efficient traffic and air quality management, validated models and PM emission estimates are needed. This paper compares current available emission factor estimates for PM₁₀ and PM_2.5 from emission databases and different emission models, and validates these against eight high quality street pollution measurements in Denmark, Sweden, Germany, Finland and Austria.The data sets show large variation of the PM concentration and emission factors with season and with location. Consistently at all roads the PM₁₀ and PM_2.5 emission factors are lower in the summer month than the rest of the year. For example, PM₁₀ emission factors are in average 5–45% lower during the month 6–10 compared to the annual average.The range of observed total emission factors (including non-exhaust emissions) for the different sites during summer conditions are 80–130 mg km⁻¹ for PM₁₀, 30–60 mg km⁻¹ for PM_2.5 and 20–50 mg km⁻¹ for the exhaust emissions.We present two different strategies regarding modelling of PM emissions: (1) For Nordic conditions with strong seasonal variations due to studded tyres and the use of sand/salt as anti-skid treatment a time varying emission model is needed. An empirical model accounting for these Nordic conditions was previously developed in Sweden. (2) For other roads with a less pronounced seasonal variation (e.g. in Denmark, Germany, Austria) methods using a constant emission factor maybe appropriate. Two models are presented here.Further, we apply the different emission models to data sets outside the original countries. For example, we apply the “Swedish” model for two streets without studded tyre usage and the “German” model for Nordic data sets. The “Swedish” empirical model performs best for streets with studded tyre use, but was not able to improve the correlation versus measurements in comparison to using constant emission factors for the Danish side. The “German” method performed well for the streets without clear seasonal variation and reproduces the summer conditions for streets with pronounced seasonal variation. However, the seasonal variation of PM emission factors can be important even for countries not using studded tyres, e.g. in areas with cold weather and snow events using sand and de-icing materials. Here a constant emission factor probably will under-estimate the 90-percentiles and therefore a time varying emission model need to be used or developed for such areas.All emission factor models consistently indicate that a large part (about 50–85% depending on the location) of the total PM₁₀ emissions originates from non-exhaust emissions. This implies that reduction measures for the exhaust part of the vehicle emissions will only have a limited effect on ambient PM₁₀ levels.     

铬渣与生活垃圾混合堆置时Cr^6＋的迁移转化规律

以实验室模拟试验探讨含Cr~(6+)的铬渣与生活垃圾、建筑弃料混合堆置时,Cr~(6+)的迁移转化规律。试验结果表明,铬渣与生活垃圾或建筑弃料进行混合堆置时,生活垃圾和建筑弃料均具有截留Cr~(6+)的能力。而生活垃圾的截留能力强于建筑弃料;生活垃圾等废弃物对Cr~(6+)还原、吸附后,转化为难以再溶出的结合态铬,吸附态铬所占比例<1.0％。     

葫芦岛市城市生活垃圾成分分析及处置对策

通过对葫芦岛市城市生活垃圾成分调查分析,基本掌握了垃圾物理成分组成、无机物百分比和有毒有害化学物质的含量,提出了对丹东市城市垃圾处置的建议.     

城市高架道路对局地大气环境影响的数值模拟研究

根据城市高架和街道的布局与几何特点,设计了多种典型的街道峡谷模型。应用k-ε湍流模型和污染物浓度扩散方程,采用数值模拟技术预测了这些带高架的城市街道峡谷内湍流流场和污染物浓度场。研究表明,高架道路的存在改变了街道峡谷内大气的流动结构和汽车排放污染物的传输扩散特性。高架道路空间位置的布设及高架与街道建筑物间的间隙,对城市街道峡谷的局地大气环境有显著影响。因此,在确定布设高架位置和设计规划街道布局时,应尽量避免引起“盖子效应”而造成严重的地面局地大气污染。     

城市建设项目环境影响评价的探讨

新一轮经济发展带动城市建设将以更高起点和速度跨入新的历史阶段。随着《环境影响评价法》的实施，城市建设项目的环境影响评价工作日益增多，在实践工作的基础上，根据这类项目的特点，提出了一些新的思路。     

活性污泥二次污染问题的探讨

讨论了城市污水经过A／O工艺处理时活性污泥的二次污染问题。所采用的方法是将原水、处理后的出水及活性污泥用乙酸丁酯萃取、萃取相经过真空浓缩后，采用GC／MS测定了样品中的有机化合物。结果表明，在A／O工艺处理城市污水过程中，活性污泥的吸附作用是主要的，降解作用是次要的：A／O工艺所排放的活性污泥仍然是一种危险的污染物。     

南京城市建设中突出的环境问题及管理对策

分析了南京市城市建设中出现的突出环境问题并提出了解决这些问题应采取的管理对策．     

浅谈城市现代化过程中的生态问题

城市现代化是社会发展的必然要求，是城市化发展的总体趋势，本文提出了城市现代化的概念，并以广州市为例，注重从生态角度上分析了城市现代化进程中存在的生态问题，指出城市现代化建设所必须遵循的生态原则，并给出了广州市目前城市现代化建设应采取的一些生态措施。     

基于循环经济的城市生活垃圾综合处理研究

城市生活垃圾是指在城市日常生活中或者为城市日常生活提供服务的活动中产生的固体废物以及法律、行政规定视为城市生活垃圾的固体废物,它和废气、废水一样,都是人类生产和生活的代谢产物.随着社会和经济的高速发展,生活垃圾已经成为了一个普遍的环境问题.在对城市生活垃圾的处理过程中,依据循环经济理论,并引入城市生活垃圾的生命周期评价,对城市生活垃圾进行综合处理,以达到垃圾处理的减量化、无害化和资源化,实现城市人与社会、环境的和谐发展.