2003-2014年珠江口香洲大气无机氮湿沉降变化研究

Deposition of Atmospheric wet Inorganic Nitrogenous Compounds in the Xiangzhou of Pearl River Estuary from 2003 to 2014

目的】研究了珠江口区域近年来大气湿沉降中无机氮的变化特征及其对近海海水生态系统的影响。【方法】对2003-2014年珠海市香洲地区湿沉降中NO_3^--N和NH_4^+-N浓度及湿沉降通量的变化特征进行了分析。【结果】香洲地区湿沉降中NO_3^--N和NH_4^+-N的浓度均有明显的季节变化,表现为旱季高而雨季低,与降雨量呈相反的变化趋势;氮素的浓度在年际变化有波动,但无明显变化趋势;氮素湿沉降通量与浓度变化相反,雨季明显高于旱季;降水量、当地污染状况、大气中污染物(气溶胶粒子)浓度、降雨类型以及气象条件等因素是造成季节差异的主要原因;此外,香洲地区大气无机氮湿沉降具有很强的事件特征。【结论】香洲地区氮素湿沉降浓度春秋季高于海水,且DIN成分比例与海水有差异,可能改变表层水体营养盐结构,影响浮游植物的生长。

【Objective】To study the characteristics of atmospheric inorganic nitrogenous wet deposits and its impacts on the Pearl River estuary and the nearby ecosystems.【Method】The variations characteristics of NO3--N and NH4+-N concentration and wet deposition flux in Xiangzhou,Guangdong Province,during2003to2014were analyzed.【Result】The results showed that the concentrations of NO3--N and NH4+-N in Xiangzhou areas have obviously seasonal changes,with the higher level in dry season and lower in wet season,and changed conversely to rainfall.No obvious annual variation was observe for NO3--N and NH4+-N.However,the wet depositin flux was opposite to the variation of concentrations,and the fluxes in wet season is obviously higher than that in dry season.Precipitations,local pollution,levels of atmospheric aerosol particles,types of rainfall and meteorological conditions are the main reasons variations.In addition,the atmospheric wet deposits in Xiangzhou area had a very strong event characteristics.【Conclusion】The concentration of wetnitrogenous deposits in Xiangzhou areas is higher than that in the sea during spring and autumn;and the composition ratio of precipitation is different from that of the sea;which may change the nutrient salt structure of surface waters and have a great effect on the growth of phytoplanktons.