北方某市环境空气颗粒物中重金属污染状况研究

对我国北方某市大气颗粒物的污染状况进行了研究。在主导风向上设置采样点,于冬季、夏季分别采集TSP、PM₁₀、PM_2.5 3种不同动力学直径的大气颗粒物。采用ICP-MS对TSP、PM₁₀、PM_2.5中的元素浓度进行分析,并对3种不同粒径颗粒物中的10种重金属采用富集因子法进行评价。结果表明,北方某市环境空气颗粒物中富集程度最严重的为Cd、Pb;在采暖期,随着颗粒物粒径变小,Pb、Cd的富集指数呈现逐渐增大的趋势;非采暖期则无此趋势。     

PM<Subscript>10</Subscript> and Ultrafine Particles Counts In-Vehicle and On-Road in the Athens Area

This work presents the first results of a study concerning on-road and in-vehicle exposure to particulate matter in the area of Athens. PM₁₀ concentration measurements were conducted by TSI DustTrak, while driving along routes with different characteristics of traffic density, during September 2003–March 2004. Concurrent measurements of the ultrafine particles (UFPs) number concentration were also conducted, by condensation particle counter during part of the days. Pedestrian exposure to PM₁₀ and UFPs was also studied through stationary measurements on the kerbside of selected roads on November 2003 and February 2004. A major avenue, a heavy-trafficked road across a children hospital and two central roads, one in a residential and one in a commercial area were selected for measurement. The results indicate that every day commuters are exposed to significant concentration levels. Higher exposures were observed in heavy-trafficked areas and during rush hours. Mean PM₁₀ in-vehicle and on-road concentrations ranged from 30–320 μg/m³ and 70–285 μg/m³, respectively. The ultrafine particles number concentrations were in the range of 5.0 × 10⁴–17.3 × 10⁴ particles/cm³ in-vehicle and 3.1 × 10⁴–7.3 × 10⁴ particles/cm³ on the kerbside of a central residential road. Both PM₁₀ and UFPs concentrations presented repeated short-term peak exposures. The results clearly point out the importance of the road microenvironment (in-vehicle and on kerbside) for population exposure in urban areas.     

Coliforms removal in full-scale activated sludge plants in India

This paper investigates the removal of coliforms in full-scale activated sludge plants (ASP) operating in northern regions of India. Log2.2 and log2.4 removal were observed for total coliforms (TC) and fecal coliforms (FC), respectively. However, the effluent still contained a significant number of TC and FC which was greater than the permissible limit for unrestricted irrigation as prescribed by WHO. The observations also suggest that extended aeration (EA) process operating under high mixed liquor suspended solids (MLSS) and sludge retention time (SRT) is more efficient in the removal of coliforms. Further attempts have been made to establish the relationship between two key wastewater parameters, i.e. biochemical oxygen demand (BOD) and suspended solids (SS) with respect to fecal and TC. The relationships were observed to be linear with a good coefficient of correlation. The interrelationship of BOD and SS with coliforms manifest that improvement of the microbiological quality of wastewater could be linked with the removal of SS. Therefore, SS can serve as a regulatory tool in lieu of an explicit coliforms standard.     

Using turbidity and acoustic backscatter intensity as surrogate measures of suspended sediment concentration in a small subtropical estuary

The suspended sediment concentration is a key element in stream monitoring, although the turbidity and acoustic Doppler backscattering may be suitable surrogate measures. Herein a series of new experiments were conducted in laboratory under controlled conditions using water and mud samples collected in a small subtropical estuary of Eastern Australia. The relationship between suspended sediment concentration and turbidity exhibited a linear relationship, while the relationships between suspended sediment concentration and acoustic backscatter intensity showed a monotonic increase. The calibration curves were affected by both sediment material characteristics and water quality properties, implying that the calibration of an acoustic Doppler system must be performed with the waters and soil materials of the natural system. The results were applied to some field studies in the estuary during which the acoustic Doppler velocimeter was sampled continuously at high frequency. The data yielded the instantaneous suspended sediment flux per unit area in the estuarine zone. They showed some significant fluctuations in instantaneous suspended mass flux, with a net upstream-suspended mass flux during flood tide and net downstream sediment flux during ebb tide. For each tidal cycle, the integration of the suspended sediment flux per unit area data with respect of time yielded some net upstream sediment flux in average.     

A long-term survey on anthropogenic impacts to the water quality of coral reefs, southern Taiwan

Before 2001, the ecological protection area in the Kenting National Park (KTNP), southern Taiwan, was poorly described. In this study, a set of four-year data (2001-2004) of seawater qualities at 19 sampling sites around the Nanwan Bay in the KTNP was used to explore anthropogenic impacts to ecological environment, especially coral reefs. The parameters of water quality were analyzed immediately after collection. The results showed that higher values of nutrients and suspended solids were attributed to the higher run-off around Nanwan Bay. The fluxes of nutrients and suspended solids were consistently correlated to rainfall. Hence, equations were developed to calculate nutrient fluxes and suspended solids by using only rainfall data. Our results show that suspended solids and ammonia were the dominant factors leading to the drop in coral coverage. In summary, the water quality in the intertidal zone of Nanwan Bay has been degraded and required greater attention.     

Source characterization of fine and coarse particles at the East Mediterranean coast

Fine and coarse atmospheric particles were collected in Ashdod—a midsize industrial city on the southeastern Mediterranean coast, and in Gedera—a rural site, to characterize ambient particles and to determine their long-range transport during two major seasons—winter and summer. Manual PM2.5 and PM10 samplers, dichotomous samplers, continuous automated PM10 samplers, and denuders were used to sample particulate and gaseous pollutants.Fine and coarse concentrations in Ashdod were 21.2 and 39.6 μg m⁻³, and 23.9 and 30.5 μg m⁻³ in the fall–winter and summer campaigns, respectively. Crustal material, as calcites or dolomites mixed with silicates, dominated the coarse fraction and also the fine fraction on dusty days. In the fall–winter, S, P, and Ni were coupled with minerals. Coarse Ni was associated with crustal material during dust storms, while P originated from shipping and deposition of phosphates in the urban area around.Sulfates dominated the fine fractions in the summer season averaging 12 μg m⁻³. Multivariate analysis indicated that S was associated with As and Se, V and Ni, both associated with heavy fuel combustion, and Zn and Pb. In winter, those mixed sources were local, but in summer they were part of long-range transport. In the fall–winter, Zn and Pb were strongly associated with Mn, Ga, and Cu—elements emitted from either traffic or metal processing plants.Although the influence of crustal material on both size fractions was significant, most heavy metals were associated with PM2.5. Higher concentrations were linked to a larger number of particles in this fraction, to a larger surface area available for biochemical reaction [Harrison, R., Shi, J., Xi, S., Khan, A., Mark, D., Kinnersley, R., Yin, J., Philos, T., 2000. Measurement of number, mass and size distribution of particles in the atmosphere. Philosophical Transactions of the Royal Society 358, 2567–2579], and finally to a larger concern in regards to health effects.     

Assessment of sediment concentration and nutrient loads in effluents drained from extensively managed fishponds in France

Expansion of aquaculture has increased concern over its environmental impact. The composition of effluents from intensive aquaculture is well documented, but few data on extensive aquaculture are available. During 12 draining operations, 523 water samples were collected downstream from six extensively-managed fishponds in northeastern France. Study ponds had surface areas of 2-620 ha and were managed for production of Cyprinids and Percids. Concentrations of total suspended solids, total phosphorus, and Kjeldahl nitrogen in effluents from the ponds were greatest during the final stage of draining. Loads of phosphorus were higher than those reported for effluents of more intensive aquaculture ponds in the USA, but the source of the potential pollutants was catchments and sediment rather than feeds and fertilizer. It will be necessary to reduce the water drawdown rate during the fishing stage and possibly implement other best management practices to prevent the TSS concentration from exceeding 1 g/L.     

亚微米颗粒物和微米颗粒物中的铅在水稻叶片中的富集比较

叶片对大气颗粒物中铅的吸收富集会对水稻本身产生毒性效应,然而目前关于叶片对不同粒径颗粒物中铅富集能力的研究较少.因此,本研究采用叶片喷施等铅浓度飞灰颗粒物的方法,探讨水稻生长后期剑叶对亚微米颗粒物和微米颗粒物中铅的吸收作用,讨论不同粒径颗粒物中铅向叶片迁移的可能机制.结果表明,向水稻剑叶分别喷施等铅浓度的亚微米飞灰颗粒物和微米颗粒物后,亚微米颗粒物处理组的剑叶和稻米的铅含量均显著高于微米颗粒物处理组.亚微米颗粒物中的铅从叶片反面表皮向内扩散,富集在维管束中,并引起叶肉中铅含量的显著升高.相比之下,微米颗粒物处理组的铅向植物叶片内迁移扩散趋势较弱.基于铅同位素分析,亚微米颗粒物组飞灰源对叶肉中铅含量的贡献为80%,而微米颗粒物组飞灰源的贡献仅为31%～42%.亚微米颗粒物组铅在细胞质中的含量比例升高,由此产生的毒性作用会更大.因此,关注大气亚微米颗粒物中铅在水稻叶片的迁移富集具有一定的必要性.     

缸内直喷汽油车细小颗粒物排放特性研究

选取三辆满足国六排放标准的缸内直喷汽油车进行常温冷启动WLTC循环排放试验,研究不同车辆排放的粒径在23nm以上的固态颗粒物、6nm以上包含挥发性/半挥发性组分的颗粒物数量排放特性,并进行了比较研究.结果发现,在缸内直喷汽油车排放的6~30nm范围内包含挥发性/半挥发性物质的细颗粒物主要产生在WLTC循环减速段､高速段和超高速段;30~2500nm范围的挥发性/半挥发性的颗粒物主要在超高速段生成;其它工况下,23nm以上固态颗粒物在颗粒物数量排放中占主体.试验研究还发现GPF对6~30nm大小的细颗粒物捕集效果不佳,并且GPF再生时会产生高浓度6~30nm大小的细颗粒物排放.颗粒物碳质成分分析表明挥发性/半挥发性细颗粒物对法规测量的23~2500nm颗粒物的数量排放影响甚微,但对颗粒物质量排放影响明显.