Effect of the air pollution on atmospheric visibility in Beijing-Tianjin area

Simultaneous measurements of air pollutant concentrations and atmospheric visibility were made in Beijing and Tianjin areas in 1983-1985. The relationship between air pollution and visibility was studied. It was found that atmospheric particulates have the most high contribution to visibility decreasing. The percentages of contributions of sulfates and soot are 52-58% and 22-29% respectively. According to the results, we suggest that the emission of SO2 and particulates must be controlled in order to improve the atmospheric visibility.     

Status of air pollution in Beijing

A study has been made on elements organic constituents, TSP, SO2,NO2 of atmospheric pollutants in Beijing. 17 elements, and some PAHs, e. g. B(a)P, B(b, j, k)P, and B(g, h, i)P, in airborne particles by X-ray fluorescence spectroscopy and HPLC, GC/MS, have been determined respectively. It has been shown that the elements Pb, Zn, S and Cu were more enriched in fine particles and different valence states of sulfur at various sites. It was found that the concentrations of S6+ and S2-were more than 85% and less than 15% of the total sulfur respectively. Concentrations of major PAHs and sulfur-containing compounds increased in winter and in urban area. High values for Pb and Zn in city, Fe and Mn at industrial area and Cu, Al rural sites were obtained respectively. This implies the functions of different elemental sources of various sites. Thus, elements can be from distingushed anthropogenic and natural sources.The main contribution of SO2 was found of to have same seasonal variation as the anthropogenic el     

Effects of atmospheric gases on terrestrial plants and critical levels of air pollution

An integrated approach was developed to determine the critical levels of air pollution for ecological standard setting based on the unified index of biological response, by taking into account the effects of all pollution components simultaneously. An empirical model of plant productivity was taken as the dose response model for gaseous pollutant effect on the productivity of trees and the annual productivity of plants was used as the above mentioned index. The CO2 increase in the lower atmosphere was considered to potentially increase plant productivity and NO2 was estimated as neutral while being dangerous for plants as a chemical precursor of ozone or as a source of acidification. The maximum permissible chronic O3 and SO2 levels for trees were estimated and it was found that O3 is much more phytotoxic, as compared to SO2 , with a rather narrow range of permissible levels (27-33 ppb) which complicates its monitoring and control.     

GIS-based analysis of population exposure to PM2.5 air pollution—A case study of Beijing

PM_(2.5), formally defined as particulate matter with diameter less than 2.5 μm, is one of most harmful air pollutants threatening human health. Numerous epidemiological studies have shown that both short-term and long-term exposures to PM_(2.5) are strongly linked with respiratory diseases. In this study, various types of spatio-temporal data were collected and used to estimate the spatio-temporal variation of PM_(2.5) exposure in Beijing in 2014. The seasonal and daily variation of the population-weighted exposure level(PWEL) in 2014 was estimated and compared. The results show that the population exposure to ambient air pollution differs significantly in the four seasons, and the exposure levels in winter and spring are notably higher than the other seasons; the exposure level changes greatly from North to South, and each sub-district maintains similarity to neighboring sub-districts.     

Photochemical pollution in Lanzhou, China - A case study

The photochemical air pollution in Xigu district of Lanshou city, Gansu Province was studied during a period of 1981-1984. The extremely high NMHC/NOx ratio and ozone level elevation after rain have been noticed. A series of outdoor and indoor reaction chamber simulation experiments conducted in order to understand the specific conditions. The ozone formation under NMHC/NOx condition and the possible reason for high ozone concentration after rain are discussed.     

Assessing the impact of air pollution sources in Hong Kong, a densely populated city

As the simple dispersion model tested is not sufficiently accurate to predict the SO2 concentration in complex terrain commonly encountered amongst high rise buildings in Hong Kong, and the lack of comprehensive local wind data at most sites prevents the use of more advanced dispersion model to assess the impact of major air pollutant sources, a receptor model approach is adopted for the apportionment of air pollution sources in Hong Kong. The preliminary results obtained are presented and discussed.     

The traffic emission and its impact on air quality in Guangzhou area

A comprehensive field measurement was set up in Guangzhou City of China and the key was placed on NO_x and O₃ pollution. The results indicated that the average driving speed of vehicle was only 14 km/h in downtown with high frequency of idle and acceleration. Upward fluxes of CO and NO were observed in Dongfeng street. NO_x annual mean concentration in urban area increased year by year, and NO_x was identified as the most important pollutant since 1995. Photochemical smog pollution was serious in general,spatial and seasonal distribution of O₃ was observed. O₃ concentration was kept in a high level in autumn, and its formation was restrained in summer due to frequent thunderstorm and high humidity. The numerical simulation showed the average concentration and maximum concentration of O₃ would increase 60%—100% if vehicular emission increased 100% in Guangzhou.     

Analysis of air quality characteristics of Beijing–Tianjin–Hebei and its surrounding air pollution transport channel cities in China

Beijing–Tianjin–Hebei(BTH) and its surrounding areas are very important to air pollution control in China.To analyze the characteristics of BTH and its surrounding areas of China,we collected 5,641,440 air quality data from 161 air monitoring stations and 37,123,000 continuous monitoring data from air polluting enterprises in BTH and surrounding cities to establish an indicator system for urban air quality portraits.The results showed that particulate matter with aerodynamic diameters of 2.5 μm(PM_(2.5)),particulate matter with aerodynamic diameters of 10 μm(PM_(10)) and SO_2 improved significantly in 31 cities from2015 to 2018,but ozone deteriorated.Air quality in BTH and the surrounding areas showed obvious seasonal characteristics,among which PM_(2.5),PM_(10),SO_2,and NO_2 showed a "U" type distribution from January to December,while O_3 had an "inverted U" distribution.The hourly changes in air quality revealed that peaks of PM_(2.5),PM_(10) and NO_2 appeared from 8:00 to 10:00,while those for O_3 appeared at 15:00–16:00.The exposure characteristics of the 31 cities showed that six districts in Beijing had the highest air quality population exposure,and that exposure levels in Zhengzhou,Puyang,Anyang,Jincheng were higher than the average of the 31 investigated cities.Additionally,multiple linear regression revealed a negative correlation between meteorological factors(especially wind and precipitation) and air quality,while a positive correlation existed between industrial pollution emissions and air quality in most of BTH and its surrounding cities.     

Regional assessment of cadmium pollution in agricultural lands and the potential health risk related to intensive mining activities： A case study in Chenzhou City, China

The purpose of this study was to assess the extent of cadmium （Cd） contamination in agricultural soil and its potential risk for people. Soils, rice, and vegetables from Chenzhou City, Southern China were sampled and analyzed. In the surface soils, the 95% confidence interval for the mean concentration of Cd varied between 2.72 and 4.83 mg/kg （P 〈 0.05） in the survey, with a geometric mean concentration of 1.45 mg/kg. Based on the GIS map, two hot spot areas of Cd in agricultural soils with high Cd concentrations were identified to be located around the Shizhuyuan, Jinshiling, and Yaogangxian mines, and the Baoshan and Huangshaping mines, in the center of the city. About 60% of the total investigated area, where the agricultural soil Cd concentration is above 1 mg/kg, is distributed in a central belt across the region. The critical distances, at which the soil Cd concentration were increased by the mining activities, from the mines of the soils were 23 km for the Baoshan mine, 46 km for the Huangshaping mine, and 63 km for the Shizhuyuan mine, respectively. These are distances calculated from models. The Cd concentrations in rice samples ranged from 0.01 to 4.43 mg/kg and the mean dietary Cd intake from rice for an adult was 191 μg/d. Results of risk indexes showed that soil Cd concentrations possessed risks to local residents whose intake of Cd from rice and vegetables grown in soils in the vicinity of the mine was 596 μg/d.     

Treatment of desizing wastewater from the textile industry by wet air oxidation

This paper describes the application of wet air oxidation to the treatment of desizing wastewater from two textile companies. A two-liter high temperature, high pressure autoclave reactor was used in the study. The range of operating temperatures examined was between 150 and 290℃, and the partial pressure of oxygen ranged from 0. 375 to 2.25 MPa. Variations in pH,CODCr and TOD content were monitored during each experiment and used to assess the extent of conversion of the process. The effects of temperature, pressure and reaction time were explored extensively. More than 90 ％ CODCr reduction and 80 ％ TOC removal have been obtained. The results have also been demonstrated that WAO is a suitable pre-treatment methods due to improvement of the BOD5/CODCr ratio of desizing wastewater. The reaction kinetics of wet air oxidation of desizing wastewater has been proved to be two steps, a fast reaction followed by a slow reaction stage.     

沈阳市空气污染特征

以沈阳市8个国控环境空气监测点位和一个清洁对照点位2004年全年小时浓度为基础数据,研究了沈阳市空气PM₁₀、SO₂和NO₂的季节变化、日变化、空间分布及综合污染指数(API)等空气污染特征,并用1995～2004年的监测数据,分析了沈阳市空气质量的总体变化趋势.结果表明,首要污染物为PM₁₀,其空气污染具有典型的煤烟型污染季节特征,环境空气质量在1995～2004年期间逐年好转.     

Urban structure and air pollution

Representative driving cycles across the Perth, Western Australia, metropolitan region illustrate a direct relationship to urban land use. Movement away from the central business district results in fewer traffic events, higher speeds, longer cruise periods and shorter stops. The consequent reduction in root mean square acceleration leads to a corresponding reduction in vehicle emission factors. Urban planning implications are pursued and highlight the importance of public transport as an option in reducing urban air pollution.     

Intercontinental transport of air pollution

There is an increasing interest on the intercontinental transport of air pollution among the three main emission regions at northern mid-latitudes: North America, Europe, and East Asia. Air pollutants with sufficient long lifetime can be transported from one continent to another. Observations from ground sites, aircraft and satellites have demonstrated this intercontinental-scale transport of air pollutants in the free troposphere. Numerical models have been applied to understand the pathways of the transport and the impact of intercontinental pollution transport. This paper reviews current observational evidence and modeling studies of intercontinental transport of ozone and its precursors, and the resulting impacts on air quality.     

Sodar in air pollution meteorology

Information concerning atmospheric stability and turbulence is basic in studies related to air pollution meteorology. In this context a monostatic sodar has been operating at the National Physical Laboratory, New Delhi, for many years to probe the thermal structure of the lower atmosphere in real time and space.Various observed thermal structures viz. nocturnal inversion, thermal plumes, formation and break-up of inversion, orographical mixing, multilayered structures and waves etc., are the result of the different atmospheric stabilities and turbulence conditions. These structures have been studied in the light of surface measurements of wind speed and direction for organized indexing of the structural details to infer meteorological conditions concerning Pasquill stability classifications.The height of the ground-based thermal structure has been correlated with the Richardson number, Ri, for quantitative estimation of the turbulence parameter. Estimated values of Ri have been further used to determine the cross wind dispersion coefficient, σ_y. The results obtained are realistic and can be used as input parameters for air pollution modelling.     

京津冀大气污染传输通道区大气污染时空格局研究

客观理解京津冀大气污染传输通道城市（“2+26”城市）空气污染时空格局对于区域大气污染联合防治具有重要意义.本研究采用遥感数据反演的PM_2.5浓度产品，利用趋势分析法和重心分析法，揭示了京津冀城市大气污染传输通道区2000~2015年大气污染时空格局演化特征.结果表明：（1）区域PM_2.5平均浓度整体呈现出太行山脉区域较低，太行山脉以东较高的格局，城镇地区明显高于周边地区.（2）2000~2015年区域PM_2.5年均浓度总体呈增加趋势，主要表现在2000~2007年，呈显著增加趋势的面积占全区的88.48%，之后呈稳定状态.（3）区域PM_2.5污染重心位于衡水、邢台和德州3市交界处，区域北部大气污染较严重.本研究可为京津冀及周边地区大气污染防治政策制定和措施实施提供参考与支持.     

京津冀地区重污染天气过程的污染气象条件数值模拟研究

通过采用全球再分析格点资料的统计分析和WRF中尺度数值模拟,从天气学和大气边界层气象学角度分析了2013年12月和2014年2月两次重污染过程中京津冀地区天气尺度大气停滞气象条件和大气污染扩散气象条件的特征及其作用,并根据WRF模式精细化模拟结果分析了太行山和燕山对京津冀地区城市大气污染形成的作用.研究结果表明,两次重污染天气过程中京津冀地区500 h Pa等压面上的平均风速均表现为明显的气候异常特征,500 h Pa平均风速较近10年同期分别下降了约30.8%和50.4%,大气停滞系数较近5年同期分别偏高10%和20%以上;京津冀地区发生严重污染时,WRF模式模拟的日平均混合层高度低于200 m,日平均地面10 m风速低于2 m·s-1,日平均通风量可降低到1000 m2·s-1以下,空气质量指数与日平均通风量成负相关,重污染期间的平均通风量比近5年同期平均通风量偏低29.3%~52.8%,这些不利于污染扩散的天气条件持续数日,导致了重污染天气的发生.此外,太行山对西风气流的阻挡是河北中南部地区大气污染加剧的一个重要原因,而当主导风向为偏南风时,偏南气流遇燕山后或转向回流、或爬坡,导致近地面风速减小,不利于污染物扩散,亦加剧了京津冀地区中南部城市的大气污染.     

室内空气质量及污染控制

分析了室内空气污染的成因及影响 ,论述了我国室内空气污染的基本特征及污染现状 ,提出了控制室内空气污染、改善室内空气质量的措施。