中文摘要：

有机氮是海洋大气气溶胶和雨水中的重要氮组分,其中的尿素氮由于具有生物可利用性以及广泛的自然源和人为源,故其沉降入海后可能对海洋生态系统产生重要影响.利用2006年11～12月和2007年2～3月在东海航次中采集的23个总悬浮颗粒物样品、4套安德森分级样品以及10个雨水样品,分析了其中尿素氮、氨氮和硝氮的浓度.在冬、春季节,气溶胶中尿素氮的浓度分别为0.2～17.7 nmol·m^-3和6.5～14.6 nmol·m^-3,雨水中的浓度分别为7.8～18.1μmol·L^-1和12.1～35.3μmol·L^-1.在气溶胶和雨水中,尿素氮的浓度均表现为春季高于冬季.相对于氨氮和硝氮,尿素氮在气溶胶中对氮组分的贡献约为5%,在雨水中的贡献接近20%.与氨氮、硝氮的粒径谱分布不同,尿素氮在各粒径段所占的比例相差不大.春季,尿素氮在0.43～0.65μm细粒子上的贡献稍高,为19.8%,冬季,在3.3～4.7μm粗粒子上的贡献稍高,为20.0%.因子分析结果表明气溶胶中尿素的浓度在冬季主要来自土壤尘的贡献,春季则主要与土壤中尿素的升华有关.

英文摘要：

Organic nitrogen is a quantitatively important component of fixed nitrogen in atmospheric aerosol and rainwater. Urea as a possible candidate of organic nitrogen component might have a significant influence to the marine ecosystem since its bioavailability and broad range of natural and anthropogenic sources. 23 total suspended particulate samples, 4 size-segregated particles samples and 10 rainwater samples collected over the East China Sea from Nov. to Dec. , 2006 and Feb. to Mar. , 2007 were applied to analyze the concentrations of urea, nitrate and ammonium in aerosols and rainwater, respectively. In winter and spring, the concentrations of urea nitrogen were from 0.2 nmol·m^-3 to 17.7 nmal·m^-3and 6.5 nmol·m^-3 to 14.6 nmol·m^-3 in bulk aerosols, respectively and the corresponding concentrations were from 7.8μmol·L^-1 to 18.1 μmol·L^-1 and 12.1 μmol·L^-1 to 35.3 μmol·L^-1 in rainwater. In both aerosols and rainwater over the East China Sea, the concentrations of urea nitrogen were higher in spring than those in winter. Urea nitrogen in aerosols contributed about 5 % to the three measured nitrogen species and it was about 20% in rainwater. The size distribution of urea was markedly different from those of nitrate and ammonium,which had no pronounced difference among cascade stages. A slightly enhance urea contribution presented in the range of 0.43- 0.65μm in spring, which was 19.8%. In contrast, an enhancement presented in the range of 3.3-4.7 μm in winter, which was 19.8%. Factor analysis indicated that the sources of urea in aerosols were dominated by wind-blown soils in winter and sublime of urea in soils in spring, respectively.