| In August,2013, We selected the typical urban roads forest belt—An Li Road section of the Beijing Olympic Forest Park as experimental plots, studied the diurnal and spatial variation of air particulate matter of urban trunk road in the summer, the influence of different configuration modes on the road's PM diffusion, correlation analysis around the small environment, traffic volume and other non-biological factors while making the air particulate matter. Preliminary draw the following conclusions:(1)The diurnal variation of summer urban trunk air particulate matter TSP, PM10 are consistent, showing approximate "two peak two valley"-type "?"-type changes. Two peaks appeared at 7:00 to 9:00 and 1:00-3:00. The two valleys appeared at 13:00 to 15:00 and 5:00. The diurnal variation of PM2.5 and PM1.0 are similar, which is "a single peak-valley" shape in the day. And both the peak occured at 3:00 am, the valley occurred at 15:00.(2) The proportion of diurnal variation of particulate matter smaller particle size, PM10/TSP, PM2.5/PM10, PM1.0/PM2.5 caught three showed significant diurnal variation. PM10/TSP diurnal variation of a "V"-type or "single peak-valley" type, PM2.5/PM10 was similar to "W" type, diurnal variation PM1.0/PM2.5 around 13:00 in the emergence of a distinct peak.(3)The level of variation of particulate matter in the air: the trend level four different size particles are not identical, but it generally shows that the level change of the four kind of PM in different size in the overall observation points is higher than the observation points in the road next to the shelter and it in line with the way the air horizontal diffusion of the general rules to pollution as the center to the sides of a decreasing trend.(4) The vertical variation of particulate matter in the air: the vertical variation of TSP and PM10 are basically the same, both during the day showed elevated particulate matter concentrations decreased with height, usually at night variation increased with height increased. In forest, the vertical variation of PM2.5, PM1.0 was 4m at the highest concentration, followed by 6m, 1.5m at the lowest concentration and the lowest concentration of CK was 1.5m, 4m at the second, the highest concentration of was 6m.(5) The highest levels of the proportion concentration of PM10/TSP, PM2.5/PM10, PM1.0/PM2.5 typically appeared at those areas which in or around pollution sources or close to high plant density place, the minimum value often appeared at open areas, which conducive to the particle spread.(6) The same road green belt around the different plant configuration mode air particulate matter concentration were different, which Joe Grass-type mode TSP and PM10 was significantly less than the shrub and tree, shrub and grass grass type, PM2.5 and PM1.0 both were slightly smaller. Open lawn lush vegetation than stand around four kinds of particle concentration of particulate matter were small.(7) Environmental factors and the four PM concentrations correlation were analyzed, we found that the temperature, humidity and traffic had great impact on the concentrations of particulate matter, including temperature and four particles showed a significant negative correlation; humidity showed a significant positive correlation with PM2.5, PM1.0 but showed a significant correlation with TSP, PM10; traffic was significantly positively correlated with TSP, PM10, while it only showed significant correlation with PM2.5 and PM1.0. |
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