Carbon Monoxide Concentration in a Street Canyon of Buenos Aires City (Argentina)

The analysis of three years of 8-h CO concentration values registered in a deep street canyon downtown shows high frequency of values that exceed WHO health protection guidelines. An inverse relationship between opposing percentiles of the distributions of CO concentrations and mean wind speed could be found. Data also showed a variation of mean CO values with prevailing wind direction. The averaged concentration value obtained when the sampler probe is on the leeward side is lower than the obtained when it is on the windward wall. A preliminary explanation of this feature may be related to the advection of polluted air from a high traffic density area nearby.     

Design of an Air-Quality Surveillance System for Buenos Aires City Integrated by a NO x Monitoring Network and Atmospheric Dispersion Models

This paper presents an air-quality surveillance system designed to detect the occurrence of air pollutant concentrations greater than a reference level in an urban area. The system is integrated by an air-quality monitoring network and atmospheric dispersion models simulations. An objective methodology to design an urban air-quality monitoring network is proposed. This methodology is based on the analysis of air-quality modelling results. The procedure is applied to design an air-quality monitoring network to control NO _x concentration levels in Buenos Aires City. Results indicate that six monitors will detect the occurrence of concentration greater than the air-quality guidelines with an efficiency of about 67%. Once a violation is detected, results of atmospheric dispersion models will help in the determination of affected areas. Four possible examples are included to illustrate the assistance that the results of atmospheric dispersion models can bring to a better estimation of possible affected areas in the city. Combining these results with the last census data, an estimation of the inhabitants possibly exposed is obtained.     

SO2对硫酸雾干扰及其消除研究

针对《固定污染源废气硫酸雾的测定离子色谱法》在污染源测定过程中SO₂引入的正干扰问题,通过实验进行了干扰物确认及消除方式研究。结果表明,在无氧条件下,SO₂不会对硫酸雾产生正干扰,而在有氧气存在条件下标准方法中的碱性吸收液会吸收部分SO₂并最终转化为SO₄^2-,使硫酸雾测定结果偏高。硫酸生产企业测定结果显示被吸收的SO₂约占其排放量的30%⁵9%。在原有吸收液中加入1%甲醛作为改进吸收液,可使采集到的SO₂以SO₃^2-形式稳定存在,不会对目标化合物SO₄^2-产生干扰且稳定时间至少为30 d。采用改进吸收液采集硫酸雾可有效防止SO₂引入正干扰,且对硫酸雾测定结果无影响。     

Spatial and Temporal Trends of Physicochemical Parameters in the Water of the Reconquista River (Buenos Aires, Argentina)

The Reconquista river is one of the most polluted watercourses in Argentina. More than 3 million people and over 10,000 industries are settled on its basin. The available data show that pollution is mainly related to the discharge of domestic and industrial liquid wastes that are poured into the river almost untreated. At present no site of the river can be characterized as free of pollutants. Samples were taken monthly from 5 sites of the river; some 18–20 physicochemical parameters were determined in each sample. Analyses revealed significant differences in the degree of deterioration between sites. Two of them, close to the source of the river (Cascallares-S₁ and Paso del Rey-S₂) resulted less polluted than the two points located close to the mouth of the river (San Martin-S₄ and Bancalari-S₅). The worsening of the water quality in S₄–S₅ was attributed to the discharges of the Moron stream, a tributary that flows into the main course of the river a complex mixture of non treated waste waters. PCA was used in the ordination of samples (sites, season and physicochemical parameters). In the PCA performed using all variables, the first principal component showed positive correlation with N-NH₄ ⁺, conductivity, orthophosphate, BOD₅, COD and alkalinity, and negative correlation with DO. The second principal component was positively correlated with pH, temperature and chlorophyll a and negatively with phenols and hardness. In respect to the spatial distribution, the plot of the scores for the first two components of samples taken in each sampling station showed S₁ and S₂ values displayed farthest at the left side of the X axis with high DO. In contrast, S₄ and S₅ values stayed at the right side of this axis with high N-NH₄ ⁺, conductivity, orthophosphate, BOD₅, COD and alkalinity; data of S₃ were “intermediate". In order to identify seasonal trends in the concentration of contaminants scores of cases labeled by season were plotted. The line drawn on the ordination plane showed that summer samples tended to converge to the upper right portion of the graph where pollution variables had more importance on the first axis, and along the second axis with high correlation with pH, temperature and chlorophyll a. Winter scores were settled in the left lower part of the plot with minor contribution of pollution parameters and more importance of DO on the first axis. Samples of autumn and spring did not fit a clear cut pattern. Deceased     

新疆克孜勒苏河喀什市段入河污染物估算及特征分析

依据污染源调查资料,采用距离法对克孜勒苏河喀什市段污染物的入河量进行估算。结果表明:污水处理厂排放口是克孜勒苏河喀什市段最主要的污染源,COD、NH3-N、TN、TP的排放量占研究区域总量的61%~83%;其次是豆腐厂总排口,4项指标占研究区域总排放量的17%~37%,也是该河段的主要污染源。两者各指标排放量之和均超过区域总量的98%。不同类型的污染源中,生活源COD、NH3-N、TN、TP的贡献率分别是工业源的2、5、4和1.6倍。     

桂林市城区大气VOCs污染特征及对O3和SOA的生成潜势

对桂林市城区大气中挥发性有机物(VOCs)的污染特征,以及VOCs对臭氧(O3)和二次有机气溶胶(SOA)的生成潜势进行了研究。结果显示,研究期间,共检出VOCs物种78种,平均体积分数为21.32×10-9,表现为芳香烃(67.82%)烷烃(19.56%)卤代烃(7.50%)烯烃(2.86%)含氧挥发性有机物(1.41%)。VOCs体积分数空间分布呈现市中心和下风向郊区两个高值区。通过苯与甲苯的浓度比值发现,林科所VOCs主要来自交通源和生物源,师专甲山校区VOCs主要是来自交通源,其余测点VOCs主要来自交通源、工业源和外来传输源。分析乙苯和间/对二甲苯的浓度比值发现,电子科大尧山校区气团光化学年龄较大,光化学反应活性相对较强烈;旅游学院、华侨旅游经开区、大埠中心校气团光化学年龄较小,光化学反应活性相对较弱。VOCs对O3生成潜势最大的为芳香烃(93.81%),其次是烷烃(7.22%)和烯烃(4.75%);对SOA生成潜势最大的为芳香烃(97.45%),其次是烷烃(2.55%)。     

Air Quality in Norwich, UK Multi-Scale Modelling to Assess the Significance of City, County and Regional Pollution Sources

Norwich is the eastern most city in the United Kingdom. Despite a population of only 100,000 and very little local industry, studies have shown that the city experiences levels of nitrogen dioxide, ozone, particulates and sulphur dioxide exceeding the UK Air Quality Standards. Because of Norwich's situation within a large, predominantly rural area a large non-resident workforce is one factor that contributes to large, often very congested traffic flows. The city's location close to the European mainland also exposes it to polluted airmasses transported from the continent, especially in the case of particulates and ozone. In order to assess the relative contributions of local and regional sources, data from rural and urban monitoring sites are to be used in conjunction with ADMS-Urban and the UK Meteorological Office's NAME model.     

一氧化氮标准气体中二氧化氮杂质FTIR定量方法研究及标气质量分析

一氧化氮标准气体在我国空气质量监测工作中广泛用于氮氧化物分析仪的校准,标准气体的质量对环境空气中氮氧化物的测量结果也有着显著的影响。利用傅里叶变换红外光谱仪建立了一套精确测量低浓度二氧化氮方法,并对一氧化氮标准气体产品中二氧化氮杂质进行了测量。结果显示有少部分样品中存在较高浓度的二氧化氮杂质。进一步讨论了可能导致一氧化氮标准气体中二氧化氮杂质偏高的原因,及此种情况对化学发光法氮氧化物分析仪准确测量空气中氮氧化物可能产生的影响。为了准确校准化学发光法氮氧化物分析仪,应关注一氧化氮标准气体产品中的二氧化氮杂质的含量。     

Roadside Concentration of Gaseous and Particulate Matter Pollutants and Risk Assessment in Dar-Es-Salaam, Tanzania

This study used manual air sampling method to assess the contribution of road traffic to air pollution level in Dar-es-Salaam City, Tanzania. Samples were collected from 11 different sites. Parameters measured were: sulphur dioxide using pararosaniline method, nitrogen dioxide using saltzman method, particulate matter and particulate lead using filtration method and atomic absorption spectrometric method, respectively. Results showed that hourly average sulphur dioxide concentration range from 127 to 1385 g/m³. The measured values of sulphur dioxide were above the recommended WHO guidelines with an hourly objective value of 350 g/m³ at 87% of the sampling sites. The hourly average nitrogen dioxide concentration ranged from 18 to 53 g/m³. The maximum hourly nitrogen dioxide concentration at 53 g/m³ was below the WHO guideline value of 200 g/m³. The hourly average suspended particulate matter (SPM) ranged from 98 to 1161 g/m³, exceeding the recommended value of 230 g/m³ by WHO at 87% of the sampling sites. The hourly average lead concentration was found to range from 0.60 to 25.6 g/m³, exceeding again the WHO guideline value of 1.5 g/m³at 83% of the sampling sites. Results predicted by Gaussian model when compared with the measured values were found to have a correlation coefficient of 0.8, signifying a good correlation. The risk assessment was undertaken considering the people who spend a significant portion of their time near the roads, such as the Uhuru primary school pupils and the adult population who reside by the roadside. The unit risk realised was 18.2 × 10^–6 for adult population and 2.2 × 10^–6 for pupils, both scenarios showing risk higher than the United Sates of America Environmental Protection Agency (USEPA) acceptable limit of 1× 10^–6. Considering the magnitude of the problem at hand, this study recommends an introduction of mandatory emission tests of SPM, lead and sulphur dioxide (SO₂). The study further recommends the introduction of continuous and/or regular air quality monitoring and the use non-leaded petrol in Tanzania.     

川南6市空气中SO2和NO2空间分布特征

利用简单、方便、不用电源的被动采样技术分别对川南地区6市区域范围内空气中SO2和NO2在雨季和旱季的空间分布特征进行研究。按16 km×16 km的均匀网格布设点位162个,并在雨季于6市各选1个空气自动站布设城区点位采集空气中SO2和NO2。获得的样品经0.3%的双氧水浸提后采用离子色谱法进行分析,经换算后获得空气中SO2和NO2的浓度,了解了其含量水平,绘制了SO2和NO2的空间分布图,掌握了其空间分布特征,并对可能的来源进行了浅析。将被动采样监测结果与自动站监测结果进行相关分析,两者高度线性相关,NO2和SO2线性相关系数分别为0.901 3和0.874 5,均大于r0.05(4)=0.811 4。     

河源夏季臭氧污染特征及其成因

2015年9月至2016年8月,在广东河源城区内采用在线连续观测,分析该地区近地面臭氧(O_3)及其前体物的变化规律和相关性,重点探讨了夏季O_3污染特征及成因。结果表明,河源市城区O_3总超标天数为10 d,主要集中在7—9月。O_3浓度变化呈现明显的春、冬季低,夏、秋季高的季节变化。O_3浓度日变化呈典型单峰特征,前体物主要呈双峰变化。O_3小时浓度和CO无明显的相关性,与NO2浓度呈现较高的负相关关系;气象及HYSPLIT-4模型计算综合分析结果表明,夏季污染时段河源高空、低空气团大部来自西南方向,夏季O_3污染主要来源于珠三角区域传输和本地源排放。     

全国火电厂二氧化硫污染现状及其控制对策

火电行业飞速发展的同时引发了二氧化硫的大量排放。文章在总结全国火电厂二氧化硫排放现状的基础上提出,火电厂二氧化硫是全国二氧化硫排放大户,其排放量占全国工业二氧化硫排放量的42%,且有逐年递增的趋势,而其去除率却一直保持一个较低的水平;大型火电厂又是电厂中二氧化硫的排放大户,且主要集中在广东、江苏、河北、山东、河南等几个省,这几个省应成为火电厂二氧化硫排放的重点监控对象。文章最后提出了电厂减排二氧化硫的几点对策和建议。     

Using improved neural network model to analyze RSP,NOx and NO2 levels in urban air in Mong Kok,Hong Kong

As the health impact of air pollutants existing in ambient addresses much attention in recent years, forecasting of airpollutant parameters becomes an important and popular topic inenvironmental science. Airborne pollution is a serious, and willbe a major problem in Hong Kong within the next few years. InHong Kong, Respirable Suspended Particulate (RSP) and NitrogenOxides NO_x and NO₂ are major air pollutants due to thedominant diesel fuel usage by public transportation and heavyvehicles. Hence, the investigation and prediction of the influence and the tendency of these pollutants are ofsignificance to public and the city image. The multi-layerperceptron (MLP) neural network is regarded as a reliable andcost-effective method to achieve such tasks. The works presentedhere involve developing an improved neural network model, whichcombines the principal component analysis (PCA) technique and theradial basis function (RBF) network, and forecasting thepollutant levels and tendencies based in the recorded data. Inthe study, the PCA is firstly used to reduce and orthogonalizethe original input variables (data), these treated variables arethen used as new input vectors in RBF neural network modelestablished for forecasting the pollutant tendencies. Comparingwith the general neural network models, the proposed modelpossesses simpler network architecture, faster training speed,and more satisfactory predicting performance. This improvedmodel is evaluated by using hourly time series of RSP, NO_x and NO₂ concentrations collected at Mong Kok Roadside Gaseous Monitory Station in Hong Kong during the year 2000. By comparing the predicted RSP, NO_x and NO₂ concentrationswith the actual data of these pollutants recorded at the monitorystation, the effectiveness of the proposed model has been proven.Therefore, in authors' opinion, the model presented in the paper is a potential tool in forecasting air quality parameters and hasadvantages over the traditional neural network methods.     

Seasonal Differences in the Levels of Gaseous Air Pollutants in the Vicinity of a Waste Dump

Hydrogen sulphide, ammonia, nitrogen dioxide, mercaptans and sulphur dioxide (H₂S, NH₃, NO₂, R-SH, SO₂) concentrations were measured at the location in the vicinity of the waste dump to determine the air pollution level of these pollutants prior to the operation of the Mobile Thermal Treatment Plant. Samples were collected over one year period. Seasonal differences, and the influence of meteorological parameters (temperature, relative humidity, pressure and wind direction) on the air pollution levels were studied. Results show relatively low concentrations of H₂S, NO₂, R-SH and SO₂, while NH₃ levels were higher compared to the guideline values. Good weather conditions (high air pressure and low relative humidity) are connected to long range transport of NO₂, while higher temperatures result in elevated NH₃ and R-SH concentrations. Because of the predominant northeast wind direction (the same as the waste dump direction), the contribution of air pollution from the direction of the waste dump at the measuring site is significant, but that does not necessarily mean that the pollutants originated from that source.     

青藏高原典型城市拉萨市近地面臭氧污染特征

拉萨市作为青藏高原典型城市,环境空气质量相对较好,但臭氧污染近年来有所凸显。对拉萨市臭氧的现状与污染特征进行分析基础上,探讨臭氧污染的影响因素。结果表明:拉萨市臭氧污染表现出"来得早,去得快"的特征,与内地城市相比,拉萨市臭氧质量浓度在3月即可达到全年平均值(2015年为105μg/m~3),而9月以后将低于全年平均值,并在春末夏初达到峰值;由于青藏高原海拔高,紫外线强,相对内陆地区臭氧均值偏高,2015年拉萨市臭氧年均值比北京市和成都市分别高出7.7%、29.0%,其小时浓度变化呈中午高、早晚低的特征;拉萨市臭氧的浓度变化受空气湿度、日照时间和日均气温的影响;生物质燃料的跨界传输可能也对青藏高原地区臭氧的来源产生一定影响。     

长江南京段重点污染源有机污染物的定性分析

参考美国EPA相关分析方法,利用气相色谱-质谱联用仪对沿江重点污染源入江废水中有机物状况进行定性分析,共检出18类82种有机物,其中13种属中国优先控制污染物,分属6类有机物;10种属美国EPA优先控制污染物,分属7类有机物。通过查明入江污染源有机污染状况,为环境风险事故防范和应急预案的建立提供了科学依据。     

南京市一次连续空气污染过程的气象条件分析

利用空气污染资料、常规气象观测资料、NCEP每6h一次2.5°×2.5°再分析资料及NOAA（美国国家海洋和大气管理局）的GDAS（全球同化数据）资料,对2009年10月16日—30日南京市出现一次连续15d的空气污染过程的天气特征进行诊断分析,同时使用HYSPLIT-4后向轨迹模式对污染物来源进行模拟。结果表明：不利于污染物扩散的大气环流形势和气象要素是造成此次污染的主要原因。南京污染物的来源可以大致分为3类：一类是海上来源;一类是南京本地的局地污染来源;还有一类是北方污染物的输送。这为进一步研究长三角地区城市的空气污染来源和成因提供理论依据。     

苏州市机动车尾气中主要污染物特征分析

为了解苏州市机动车尾气中主要污染物浓度特征,运用SPSS19.0时间序列建模器,预测了未来5年(2017—2021年)苏州市机动车保有量,分析和对比了苏州市路边站点和国控站点的主要污染物数据。结果表明,未来5年,苏州市机动车保有量呈现上升趋势,2020年机动车保有量将达到373.1万辆,相比2014年增加约37.5%;路边站点NO2值略高于国控站点,但差异不显著;路边站点CO值明显高于国控站点;路边站点PM10和PM2.5值总体略高于国控站点;路边站点苯系物值高于国控站点。     

南京市机动车污染物减排因素分析

以南京市机动车排污监控系统的实时检测数据为基础,简述了南京市机动车减排效果,在“十二五”期间南京市机动车保有量增长71.8%的背景下,实现了污染物排放量削减18.8%,单车平均排放CO、HC、NOx较3年前分别下降了33%,31%和36%;排放标准和使用年限二因素方差分析表明,其对NOx、CO和HC排放值的影响由大到小排序均为：油品质量〉排放标准〉使用年限。提出,进一步提升油品质量至关重要。     

Measurements and Modelling of Air Pollution in a Street Canyon in Helsinki

A measuring campaign was conducted in the street canyon 'Runeberg street' in Helsinki in 1997. Hourly concentrations of carbon monoxide (CO), nitrogen oxides (NO_X), nitrogen dioxide (NO₂) and ozone (O₃) were measured at the street and roof levels, and the relevant hourly meteorological parameters were measured at the roof level. The hourly street level measurements and on-site electronic traffic counts were conducted during the whole year 1997, and roof level measurements were conducted during approximately two months, from 3 March to 30 April in 1997. The Operational Street Pollution Model (OSPM) was used to calculate the street concentrations and the results were compared with the measurements. The overall agreement between measured and predicted concentrations was good for CO and NO_x, but the model slightly overestimated the measured concentrations of NO₂. The database, which contains all measured and predicted data, is available for a further testing of other street canyon dispersion models.