南海东部大气湿沉降中无机氮的研究

Inorganic nitrogen in atmospheric wet deposition in Eastern South China Sea

通过分析2000至2014年菲律宾马尼拉（Manila）和洛斯巴诺斯（Los Banos）大气湿沉降资料,初步探讨近15年湿沉降中无机氮含量特征以及对南海东部海域水生生态系统的影响。结果显示,湿沉降中NO3^-N和NH4^＋-N的浓度均为旱季高雨季低;NO3^-N浓度在近15年虽有波动,但并无明显变化趋势;而洛斯巴诺斯区域的NH4^＋-N浓度自2009后稍有波动上升。NO3^-N和NH4^＋-N的沉降通量与浓度相反,表现为雨季高而旱季低,年际上总体表现为NH4^＋-N的沉降通量大于NO3^-N,马尼拉无机氮的沉降通量大于洛斯巴诺斯,并且在2003年之后,马尼拉和洛斯巴诺斯NH4^＋-N的沉降通量均呈明显上升趋势,菲律宾经济的快速增长及人类活动是主导其上升的主要因素。马尼拉和洛斯巴诺斯湿沉降中NO3^-N/NH4^＋-N值分别为0.33和0.41,该比值和无机氮浓度与南海东部各海区表层海水的值有明显的差别,因此降水可能改变该海域表层水体无机氮的组成结构,进而影响水体中浮游植物的生长及其群落结构。

Based on the collected data for atmospheric wet deposition of Manila and Los Banos in Philippine from 2000 to 2014,characteristics of inorganic nitrogen in wet deposition over the past 15 years and their impacts on the aquatic ecosystem in Eastern South China Sea were primarily discussed. Results show that concentrations of NO3^-N and NH4^＋-N in wet deposition of the two study areas are both higher in dry season whereas lower in rainy season. Although the NO3^-N level has fluctuated during the recent 15 years,obvious variation trends were observed. But the concentrations of NH4^＋-N had showed slightly increased trends from 2009 to 2014 in Los Banos,and the rapid population growth and human activity were dominant factors. The wet deposition fluxes of NO3^-N and NH4^＋-N show higher in wet season whereas lower in dry season. The wet deposition fluxes varied greatly in different years,but with the general performance as NH4^＋-N fluxes NO3^-N,and the deposition fluxes of inorganic nitrogen as Manila Los Banos. In addition,wet deposition fluxed of NH4^＋-N in Manila and Los Banos had been both significantly increased from 2003 to 2014. The average molar ratios of NO3^-N and NH4^＋-N in Manila and Los Banos are 0. 33 and 0. 41 respectively,indicating that inorganic nitrogen composition and their concentration in wet deposition are different from seawater of the eastern South China Sea. This may change the inorganic nitrogen structure and result in changing the phytoplankton production in the surface seawater of Eastern South China Sea.