Study On Distribution Of Atmospheric Particulate Inorganic Nitrogen In Qingdao And The Yellow Sea

The atmospheric aerosol samples were collected in Qingdao coastal region from June 2007 to Febrerary 2008, Qianliyan Island in 2006 and the Yellow Sea during 2007-2008. The inorganic nitrogen components were analyzed using IC (Ion Chromatography). The concentration and the size distribution of the atmospheric inorganic nitrogen and impact of weather conditions on distribution were discussed.The results of atmospheric aerosols in Qingdao coastal region showed that particle concentration distribution was spring (257.82μg/m3)>winter (207.72μg/m3)>autumn (154.54μg/m3)>summer (143.78μg/m3) in Qingdao region from June 2007 to Febrerary 2008. NO3--N concentration had the same distribution with that of aerosol particulates. NO3--N concentration was the highest in spring(4.54μg/m3) and lowest(1.66μg/m3) in summer. The seasonal distribution of NH4+-N was different with that of particulate matter and NO3--N. The NO3--N concentration had the highest value (7.90μg/m3) in winter and the lowest one(2.89μg/m3) in summer. The aerosol concentration distribution was affected by the weather conditions. The concentration of particulate matter, NH4+-N and NO3--N were lower in sunny or partly cloudy days. The concentration of particulate matter was highest in dust weather, whereas the concentration of NH4+-N and NO3--N was increased greatly in the foggy days.The mass concentration of particulate matter, NH4+-N and NO3--N increased by 82%,79% and 48% respectively in the heating period than before heating. The concentrations of particles were higher, but the NH4+-N and NO3--N concentrations were lower in sunny days during the heating period. Particulate inorganic nitrogen mainly originate from the formation of secondary aerosols by local NH3, NOx, HNO3 gas, and Qingdao was controlled mainly by air mass from the north-west, long-distance transmission,which had no significant effect on inorganic nitrogen concentration. The concentrations of particles, NH4+-N and NO3--N increased by 1-2 times in the foggy days but decreased greatly under a synoptic condition with a sharp temperature drop and a strong wind. It was mainly because that high humidity was helpful for the formation of particulate inorganic nitrogen components in the foggy day.Atmospheric size distribution of particles in the sampling period showed a bimodal distribution, with one accumulation mode peak appears in the range of 0.65-1.1μm and the coarse peak in the range of 3.3-4.7μm. NH4+-N, a major inorganic nitrogen component in the particulate matter, showed single peak in the accumulation mode of 0.43-1.1μm. NO3--N size distribution was similar to that of particles, which showed a bimodal distribution, the main peak in the accumulation mode. The proportion of fine particles to total ones has little variation in seasons except for summer being relatively high. NH4+-N was mainly existed in fine particles and the size distribution of NO3--N has clear seasonal variation. The proportion of fine particles to toal ones was the lowest in summer, higher in autumn and the highest in winter.The concentration of particulate matter had seasonal distribution, which had a higher value in winter and spring(168.30μg/m3 and 158.46μg/m3 respectively) , a lower one in autumn(115.51μg/m3) and the lowest in summer(63.81μg/m3) over the North Yellow Sea. The inorganic nitrogen accounted for 1.98 ~ 13.64% of the total mass of particulate for aerosol samples over the Yellow Sea. NH4+-N and NO3--N were major contributors of inorganic nitrogen. NH4+-N was the most important component of total inorganic nitrogen(TIN), and NO2--N was found only in some samples and contributed little to TIN over the North Yellow Sea. The seasonal distribution of inorganic nitrogen concentration were different with that of particulates, and varied in order of winter> spring> autumn> summer. The ratio of TIN to particulate matter was higher in the winter season than that in the other three seasons.The concentrations of particulate matter and inorganic nitrogen (IN) were higher in winter than in autumn on the Qianliyan island, which was the same as samples in Qingdao, but the concentrations of TSP and IN on the Qianliyan island were smaller than in Qingdao and Yellow Sea. The average concentration of particulate matter was in the range of 41.41-243.19μg/m3 with a average value of 95.84μg/m3 in the autumn. NH4+-N and NO3--N had the same variation trends as that of particles and the average concentration was 1.96(0.80-3.78μg/m3) and1.25(0.70-2.90μg/m3) respectively.The average concentrations of ammonium and nitrate were 3.80 and 2.24μg/m3, and the concentration range were 1.27-5.71μg/m3 and 0.84-4.16μg/m3 respectively in winter. NO2--N was not detected in the samples collected in autumn. The particulate inorganic nitrogen accounted for 2.90%~7.68% of particles mass in the island, which was lower than that in Qingdao. While ammonium accounted for 56.56~71.73% of TIN in the island, lower than that in Qingdao.