In this paper, the characteristics of urban heat island (UHI) and boundary layer structures in the Beijing area, China, are analyzed using conventional and Moderate Resolution Imaging Spectroradiometer (MODIS) observations. The Weather Research and Forecasting (WRF) model coupled with a single-layer urban canopy model (UCM) is used to simulate these urban weather features for comparison with observations. WRF is also used to test the sensitivity of model simulations to different urban land use scenarios and urban building structures to investigate the impacts of urbanization on surface weather and boundary layer structures. Results show that the coupled WRF/Noah/UCM modeling system seems to be able to reproduce the following observed features reasonably well: 1) the diurnal variation of UHI intensity; 2) the spatial distribution of UHI in Beijing; 3) the diurnal variation of wind speed and direction, and interactions between mountain–valley circulations and UHI; 4) small-scale boundary layer conv...

https://opensky.ucar.edu/islandora/object/articles%3A17470/datastream/PDF/view

An Observational and Modeling Study of Characteristics of Urban Heat Island and Boundary Layer Structures in Beijing

Atmospheric nitrogen (N) deposition, an important component in the global N cycle, has increased sharply in recent decades in China. Here, we constructed national-scale inorganic N wet deposition (Ndep) patterns in China based on data from 280 observational sites and analysed the effects of anthropogenic sources and precipitation on Ndep. Our results showed that the mean Ndep over China increased approximately 25%, from 11.11 kg ha−1 a−1 in the 1990s to 13.87 in the 2000s. Ndep was highest over southern China and exhibited a decreasing gradient from southern to western and northern China. The decadal difference in Ndep between the 1990s and 2000s was primarily caused by increases in energy consumption and N fertiliser use. Our findings conformed that anthropogenic activities were the main reason for the Ndep increase and provide a scientific background for studies on ecological effects of N deposition in China.

/pdf/spatial-and-decadal-variations-in-inorganic-nitrogen-wet-cjwy42rvrd.pdf

Spatial and decadal variations in inorganic nitrogen wet deposition in China induced by human activity

A study on the trends of vehicular emissions in the Beijing-Tianjin-Hebei (BTH) region, China

The contribution of fugitive dust from traffic to air pollution can no longer be ignored in China. In order to obtain the road dust loadings and to understand the chemical characteristics of PM10 and PM2.5 from typical road dust, different paved roads in eight districts of Beijing were selected for dust collection during the four seasons of 2005. Ninety-eight samples from 28 roads were obtained. The samples were resuspended using equipment assembled to simulate the rising process of road dust caused by the wind or wheels in order to obtain the PM10 and PM2.5 filter samples. The average road dust loading was 3.82 g m − 2, with the highest of 24.22 g m − 2 being in Hutongs in the rural–urban continuum during winter. The road dust loadings on higher-grade roads were lower than those on lower-grade roads. Attention should be paid to the pollution in the rural–urban continuum areas. The sums of element abundances measured were 16.17% and 18.50% for PM10 and PM2.5 in road dust. The average abundances of OC and EC in PM10 and PM2.5 in road dust were 11.52%, 2.01% and 12.50%, 2.06%, respectively. The abundance of elements, water-soluble ions, and OC, EC in PM10 and PM2.5 resuspended from road dust did not change greatly with seasons and road types. The soil dust, construction dust, dust emitted from burning coal, vehicle exhaust, and deposition of particles in the air were the main sources of road dust in Beijing. Affected by the application of snow-melting agents in Beijing during winter, the amount of Cl −  and Na +  was much higher during that time than in the other seasons. This will have a certain influence on roads, bridges, vegetations, and groundwater.

Determination of road dust loadings and chemical characteristics using resuspension.

Commuters' exposure to PM1 by common travel modes in Shanghai

Pollution property of particulates in the air and its affecting factors at the traffic crossing in Beijing were studied. Particulates samples of different sizes were collected at one of the major traffic crossings, Chongwenmen crossing, in June 2000. The mass concentration, ion concentration and element mass concentration in the particulates were measured. The flux of vehicles through the crossing during sampling was also investigated. Results showed that the pollution of particulates in the air was most serious on June 5. Especially at 0:10—3:50 on June 6, the mass concentration of PM_(2.5( was the highest. There was not obvious relationship between the pollution level of particulates in Chongwenmen crossing and the flux of vehicle. The particulates from traffic were the major factor affecting the pollution level at the traffic crossing. The elements such as Al, Ca, Fe and Mg were mainly from the raised dust carried by vehicles and Cu and Pb were mainly emitted from vehicles. The research direction and technology route in the future were also pointed out.

Pollution Property of Particulates in the Air at the Traffic Crossing in Beijing Part I: Pollution Property of Particulates in the Air and Its Affecting Factors

Studying the environmental effects of toxic air pollutants is currently very important in the world.One of the main sources of air pollutants is vehicular exhaust emissions.In this study,average annual vehicle miles traveled,emission of toxic air pollutants per year and mass fraction of NMVOC emissions were obtained through data investigations.NMVOC emission factors were calculated based on the COPERT Ⅳ model,and vehicle emission inventories of different regions and vehicles in 2005 were established.The results showed that the total amount of benzene,1,3-butadiene,formaldehyde,acetaldehyde and acrolein emitted by vehicles in China were 31.65×104,7.45×104,13.26×104,5.11×104 and 1.65×104 t,respectively,and most of them were emitted by motorcycles,gasoline PC and diesel HDT.As for the regions,the amounts of toxic air pollutants emitted by vehicles were high in Guangdong,Shandong,Jiangsu,Zhejiang,Hebei and Henan Provinces.

Estimation of Vehicle Toxic Air Pollutant Emissions in China

The data analysis of rainwater, fog water and air quality in Minnan area shows that acid rain in Minnan area is caused by the combined pollution of coal combustion and photochemical smog; the ratio of SO 2- 4 to NO - 3 of rainwater in Minnan area is the lowest among those in main acid areas of China; NO x is one of the most important precursors of acid rain; local source emission is the major source of NO - 3 of acid deposition in Minnan area.

Contribution of NO x to Acid Rain in Minnan Area

Pollution property of PAHs in the particulates in the air and its affecting factors at the traffic crossing in Beijing were studied. Samples of TSP, PM_(10( and PM_(2.5( were collected at one of the major traffic crossings, Chongwenmen crossing, in June 2000. The mass concentration of PAHs in the particulates was measured. The flux of vehicles through the crossing during sampling was also investigated. Results showed that vehicle emission was the major source of PAHs in the particulates at the traffic crossing. PAHs were mainly in the particulates of small size. The mass concentration of PAHs went up with the increase of the flux of vehicles in the daytime. At night the mass concentration of PAHs was higher than that in the daytime. The identification of pollution sources showed that a small part of PAHs in the particulates at the traffic crossing came from the raised dust in the street beside the emission of the vehicles.

Pollution Property of Particulates in the Air at the Traffic Crossing in Beijing Part II: Pollution Property of Non-Hydrocarbons in the Particulates in the Air

Tang Da-gang

Papers

Pollution Property of Particulates in the Air at the Traffic Crossing in Beijing Part I: Pollution Property of Particulates in the Air and Its Affecting Factors

Estimation of Vehicle Toxic Air Pollutant Emissions in China

Contribution of NO x to Acid Rain in Minnan Area

Pollution Property of Particulates in the Air at the Traffic Crossing in Beijing Part II: Pollution Property of Non-Hydrocarbons in the Particulates in the Air