Analysis Of Aerosol Optical Properties And Particulate Pollution At Background Station In The Pearl River Delta Region

Aerosol plays an important role in global and regional environment change. It has a significant impact on the solar radiation budget. Aerosols influence the radiation balance of the earth-atmosphere system by direct and indirect radiation effect, which is one of the most important factors in weather and climate change. As one of primary gaseous contaminant in urban ambient, Aerosol has an important effect on the atmospheric environment. Based on the data of air pollutants and meteorological parameter collected at a background station in the Pearl River Delta region, Characteristics of trace gases (O3, NOx SO2and CO), particulate matter and aerosol optical properties are explored. The levels and variations of O3, NOx, SO2and CO are analyzed and their possible causes are discussed. The major contents and conclusions are presented as follows:Measurements of gaseous pollutants (O3, NOx, SO2and CO) were conducted at Dinghushan background station in Southern China from Jan.2013to Dec.2013. The annual average concentrations of O3, NOx, SO2and CO are24.6±23.9,12.8±10.2,4.0±4.8and348±185ppbv, respectively. The observed levels of the gaseous pollutants are comparable to those at other background sites of China. The most obvious diurnal variation of O3is observed in autumn, with minima in the early morning and maxima in the afternoon. The diurnal variations of SO2show high values during the daytime. The diurnal cycles of NOx show higher values in the morning and lower values during the night. Higher CO concentrations were observed in spring followed by winter, autumn and summer. The biomass burning, in combination with the transport of regional pollution, is an important source for CO, SO2and NOx in spring and winter. Backward trajectories were calculated and analyzed together with corresponding pollutant concentrations. The results indicate that the air masses passing the polluted areas are responsible for the high concentrations of the gaseous pollutants at Dinghushan background station.Measurements of fine particles (PM2.5), coarse particles (PM10) and aerosol optical properties were carried out at a background station-Dinghushan in the Pearl River Delta (PRD) region from2009to2012. It showed that the long-term mean concentrations of PM2.5and PM10were as high as (51±31)μg/m3and (76±43)μg/m3, respectively. Particulate pollution in the PRD region was mitigated over the last four years, and the annual mean concentrations of PM2.5was decreased to (39±25)μg/m3in2012from (65±33)μg/m3in2009. The concentrations of PM2.5and PM10were low in summer and high in the other three seasons. The correlation between the daily concentrations of PM2.5and PM10was generally high (R>0.90). The long-term mean PM2.5/PM10ratio reached up to0.67, the ratio was high in autumn (0.71) and low in summer (0.57). Atmospheric visibility was poor, the long-term mean of aerosol optical depth (AOD) at500nm was0.91±0.40, Angstrom exponent was0.97±0.36. The values of AOD were low in winter and summer, high in spring and autumn. The correlation between particulate matter (PM) concentrations and AOD was high. The correlation coefficient in dry season (October-next March) was better than that was in wet season (April-September). In addition, the correlation also demonstrated great differences for different air masses.