Atmospheric ammonia distribution and contribution to PM2.5 in typical areas of Pearl River Delta.
To investigate the contribution of NH3 to fine particulate matter(PM2.5)in typical areas of the Pearl River Delta in Southern China,three urban sites(GYQ,MH,and DC)and one suburban site(HGS)in the Pearl River Delta were selected to carry out online monitoring of NH3.Water-soluble inorganic ion,nitric acid(HNO3),PM2.5 and meteorological parameters were collected simultaneously.The characteristics of concentration level and diurnal variation of NH3 were analyzed.The potential contribution of NH3 to PM2.5 was further evaluated.The observed results showed that the annual average of NH3 at GYQ,MH,DC and HGS were(5.74±3.0),(4.70±2.41),(5.09±2.26)and(4.17±1.95)µg/m3 respectively.Except for GYQ,the seasonal variation of NH3 in other sites showed an increasing trend of autumn>spring>summer>winter.The diurnal variation of NH3 concentration is similar to that of temperature,and opposite to that of relative humidity.According to the adjusted gas ratio(AdjGR),all sites exhibited high levels of NH3.With the increase of PM2.5 pollution concentration,AdjGR gradually decreased,while the ammonium-to-total ratio of NH3(NHR)gradually increased.In addition,the NHR>0.5 of the four sites mainly occurred under the meteorological conditions of temperature<25℃and relative humidity<70%.
atmospheric ammoniafine particulate matteradjusted gas ratiosecondary inorganic aerosolgas-to-particle conversion
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