鼎湖山无机氮湿沉降来源研究

针对2007年3—8月鼎湖山站的降水资料，分析了鼎湖山春夏两季氮沉降特征及其来源. 结果表明:研究期间鼎湖山NO₃--N和NH₄＋-N的降水量加权平均质量浓度分别为0.59和1.03mg/L，其中春季湿沉降中ρ(NO₃--N)和ρ(NH₄＋-N)的平均值分别为0.78和1.54 mg/L，分别是夏季的2.17和1.67倍；降水ρ(NO₃-)与ρ(NH₄＋)呈显著正相关，与降水pH呈负相关. 利用气团轨迹后推以及天气形势分析得出，影响鼎湖山氮湿沉降的主要因素是陆地性降水，其ρ(NO₃--N)和ρ(NH₄＋-N)分别为0.75和1.43 mg/L，分别是海洋性降水的1.57和2.26倍；氮沉降通量分别为3.28和6.26 kg/hm2，分别占总无机氮沉降负荷的56.0%和64.6%.进一步利用气团后向轨迹对海洋性和陆地性降水进行云下气团分类，结果表明，陆地性NE方向的气团对鼎湖山氮的输送及沉降负荷最大. 

Study on Sources of Inorganic Nitrogen in Wet Deposition in Dinghushan Mountain

Precipitation data from March 2007 to August 2007 in Dinghushan Mountain station were analyzed to study inorganic nitrogen deposition flux and its origin in spring and summer. The results showed that average concentrations of nitrate and ammonium in the rainfall in Dinghushan Mountain station were 0.59 and 1.03 mg/L respectively. In the spring, the concentrations were 0.78 and 1.54 mg/L, which were 2.17 and 1.67 times more than those in summer. ρ(NO₃-) was positively correlated with ρ(NH₄＋), but negatively correlated to rainfall pH. The correlation between nitrate and ammonium in rainfall was positive. It was found that the continental precipitation was the primary factor affecting inorganic nitrogen deposition according to analysis of the backward trajectory and synoptic pattern data of Dinghushan Mountain station. The average concentrations of NO₃--N and NH₄＋-N in continental precipitation were 0.75 and 1.43 mg/L, which were 1.57and 2.26 times more than those in oceanic precipitation, respectively. The deposition fluxes of NO₃--N and NH₄＋-N in continental precipitation were 3.28 and 6.26 kg/hm2, which accounted for 56.0% and 64.6% of total inorganic nitrogen deposition, respectively. Two air masses under clouds in oceanic and continental precipitations were identified according to backward trajectory results. Air mass coming from the northeast in continental precipitation offered the highest contribution to total nitrogen deposition flux.