|Abstract: ||本研究採集分析東海南端沿岸城市—基隆的雨水樣本，期間涵蓋2012年1月至2013年6月，共18個月，包含5次颱風事件的8個樣本，累計78個雨水樣本，針對雨水中總氮(total dissolved nitrogen, TDN)以及主要離子(Major ions)進行分析；總氮可分成無機氮(Dissolved inorganic nitrogen, DIN)和有機氮(Dissolved organic nitrogen, DON)兩類，其中DIN以銨鹽(NH4+)、硝酸鹽(NO3-)、亞硝酸鹽(NO2-)等三種營養鹽組成，而DON的種類繁多難以單獨定性區別，在本研究中以氧化法定量分析DON，為進一步討論DON的組成，使用超濾法(ultrafiltration)將DON分離成低分子量有機氮(low molecular weight-DON, LMW-DON)和高分子量有機氮(high molecular weight-DON, HMW-DON)。 整體而言，東北季風盛行時，氮物種與非海鹽性離子(nss-ion)濃度較高，並出現明顯的氯虧損現象(Chloride-loss)，此時多發生大陸性與區域性來源；西南季風盛行時，氮物種與非海鹽性離子(nss-ion)濃度偏低，氯虧損的程度輕微，此時多發生海洋性與颱風來源。 從相關性分析中可看出，DIN比DON更能代表TDN的濃度變化，DON、LMW-DON的行為模式與來源與石化燃料燃燒(fossil feul burning)有關，DIN的行為模式與大陸性來源較為有關，HMW-DON的行為模式與來源與生質燃燒(Biomass burning)有關，一般時期，NO3-與Chloride-loss的相關性較高，而在颱風事件中，nss-SO42-與Chloride-loss的相關性較高。 另外以主成分分析(Principal components analysis；PCA)解析各物種的性質，結果顯示全研究期間可解析為：第一主成分為人為活動來源，與燃燒行為有關，並伴隨明顯的氯虧損，佔54%，第二主成分為海洋性來源，氯虧損的程度輕微，佔19%，累積解釋變異量(Explained variance, EV)為73%；颱風事件可解析為：第一主成分為海洋性來源，佔44%，氯虧損的程度輕微，第二主成分為石化燃料燃燒，並伴隨氯虧損現象，佔30%，累積解釋變異量為74%。 本研究溼沉降中TDN的日沉降通量為1743± 1073μmol m-2 day-1，與同地區乾沉降的文獻比較，乾沉降中TDN的日沉降通量為168± 53.4μmol m-2 day-1，僅佔整體沉降中的9%，說明在研究區域濕沉降貢獻的氮物種遠高於乾沉降，氮物種主要以溼沉降的型態從大氣輸送至地表。|
This study analyzed 78 rain samples, including 8 typhoon samples from 5 typhoon events, collected from January 2012 to June 2013 at costal site on the southern East China Sea at Keelung city, Taiwan, for the dissolved nitrogen species and major ions. TDN(total dissolved nitrogen) could classified into DIN(dissolved inorganic nitrogen) and DON(dissolved organic nitrogen), and further, DIN was the combination of ammonium, nitrate and nitrite. DON was quantitated as two species, High molecular weight(HMW)-DON and Low molecular weight(LMW)-DON, after separated by using ultrafiltration technique and oxidize procedure. Genarally, nitrogen species and major ion showed an increasing trend and high concentration in northeast monsoon season which usually derived form continental and region sources. When southwest monsoon season, air mass were more oceanic and typhoon source accompanying with low concentration of nitrogen species. We found DIN was a better indicator to TDN rather than DON. DON and LMW-DON showed high correlation with fossel feul combustion. DIN was more likely to continental derived components. HMW-DON showed high correlation with biomass burning. Nitrate was the major factor with chloride-loss during entire sampling period, nss-SO42- showed higher relationship with chloride-loss during typhoon events on the contrary. Factor analysis revealed that two factors account for 73% of total explained variance for the entire sampling period, while two factors account for 74% of total explained variance for the typhoon events. During the sampling period, factor 1 has high loadings of buring-derived components which was classified into anthropogenic source with obvious chloride-loss and accounted for 54% of total explained variance, factor 2 was classified into marine factor, and explained 19% of total variance. During the typhoon event, factor 1 was classified as an oceanic source, and explained 44% of total variance. Factor 2 attributed to fossil fuel combustion accounted 30% of total explained variance. The flux by wet deposition calculated for TDN was 1743± 1073μmol m-2 day-1 comparing to dry deposition in the same region which was168± 53.4μmol m-2 day-1 only accounted for 9% of total deposition showing that wet deposition was the major deposition form for nitrogen species’ transportation from atmosphere to ground.