Study On Atmospheric Deposition Of Inorganic Nitrogen In Qingdao And Over China Sea

Atmospheric deposition was one of the main nitric sources of the marine and terrestrial ecosystem. The study on the atmospheric deposition of nitrogen in Qingdao offshore have an important significance on understanding the atmospheric nitrogen input to the yellow sea and the influence to the marine primary production. Aerosol samples were taken on Baguan Mountain in Qingdao from December 2004 to August 2006, rainwater samples were collected from August 2004 to August 2006 in the same region. Aerosol samples and the rainwater samples were also taken over the Yellow Sea and South China Sea. Inorganic nitrogen components (nitrate, nitrite, ammonium nitrogen) were analyzed with Ion Chromatography (IC). The concentration and the size distribution of the inorganic nitrogen in Qingdao and offshore aerosol were obtained, as well as wet deposition. The inorganic nitrogen seasonal variety and special distribution in atmospheric dry and wet deposition over the China Sea were also discussed.The results of TSP (Total Suspended Particulates) on Baguan Mountain indicated that the concentration of TSP and inorganic nitrogen were higher in winter and spring, while the concentration being the lowest in summer. The concentration of NH4+-N, NO3--N showed the similar variation with that of TSP. Sand dust weather made an obvious influence on the aerosol particle and inorganic nitrogen components in the atmosphere. There was a direct correlation between NO3- and NOx in Qingdao atmosphere.In Qingdao, the size distribution of aerosol particle presented obvious double peaks. The max peak was presented in the accumulate mode. And the lower existed in the coarse mode, and the peak in the coarse mode was especially obvious in spring dust weather. NH4+-N presented single peak in the accumulate mode. The size distribution of NO3--N was complex, presenting double peak in spring and summer, single peak in autumn and winter. Sand dust weather made an obvious influence on the aerosol particle and inorganic nitrogen components size distributions in the aerosol .After the sand dust, there were different increasing in the different size for the NO3--N and NO2--N ,but NH4+-N did not present obvious increasing except for the section of 0.43~0.65μm.NH4+-N was the major inorganic nitrogen in the rainwater collected in Qingdao, except for the individual samples. The next is NO3--N and the concentration of NO2--N was very low. There was accordant tendency between NO3--N and NH4+-N, the concentration in summer was the lowest, that in winter the highest. Also there was an anti-relation between the concentration of the inorganic components and the rainfall.Overall, the concentration of TSP and inorganic nitrogen in the aerosol over the Yellow Sea were higher than that in the South China Sea, the concentration of TSP over the Yellow Sea in spring was higher than that in summer, which was due to the sand dust weather as well as in the rain. As to the size distribution of the inorganic nitrogen in the aerosol, NO3--N presented two peaks, and most NH4+-N existed in the fine particles less than 1.1μm. In spring, NO3--N showed a peak in fine mode 0.43~0.65μm when there was no sand-dust, but presented a peak in the range of 1.1~2.1μm and 2.1~3.3μm under the sand-dust weather. In summer, the ratios of aerosol particle in fine section were lower than that in spring, otherwise, ratios in coarse section was higher. In summer, the NO3--N presented max peak value in the coarse mode and the proportions of the NH4+-N in fine section decreased.The results on the island Qianliyan indicated that in spring the concentration of TSP and inorganic nitrogen in the aerosol were higher than that in summer, as well as in the rain. In spring, particles and NO3--N in the aerosol presented double peak values, NH4+-N presented single peak in the fine mode. In summer, the peak value of the particle in the coarse mode rose obviously, NO3--N presented single peak value in the coarse mode, otherwise, extremely low value in the fine mode 0.43~0.65μm. NH4+-N presented single peak in the fine particles less than 1.1μm.The comparison was made among the samples collected at three sampling sites. The TSP concentration reduced in the order of Qingdao>Qianliyan≈Yellow sea, the concentration of NO3--N and NH4+-N decreased in the order of Qingdao>Yellow sea> Qianliyan. In spring the peak of the particle presented in the coarse mode was more obvious in Qingdao than that over the Yellow Sea, while in summer that of island Qianliyan was more obvious. In the summer, the size distribution of the NO3--N on the island Qianliyan was similar to that over the Yellow Sea, the max peak value was presented in the coarse mode, while in the fine mode in Qingdao. NH4+-N showed the same size distribution at three sampling sites, presenting single peak. The proportion of NH4+-N in the fine particles to in the coarse particles deceased in the order of Qingdao>Qianliyan>Yellow sea, which may be due to the source of the NH3. At the three sampling sites, the proportion of NO3--N accounting for total inorganic nitrogen in the rainwater was higher than that in the aerosol.The concentration of the NO2--N was very low, and the size distribution was also complex because of its unstable property.