昆明东郊大气氮湿沉降的测定与分析

Atmospheric Wet Nitrogen Deposition in the Eastern Suburb of Kunming

【目的】研究昆明东郊不同形态的氮湿沉降月均浓度变化、各形态氮的沉降量及其与降雨的关系。【方法】以昆明东郊一站点为研究对象,借助自制雨水收集器和PortLog便携式自动气象站进行降水采样与降水量的监测。【结果】总氮月均浓度的范围为（0.54-2.60mg/L）,其中铵态氮月均浓度的范围为（0.16-1.15mg/L）,硝态氮月均浓度的范围为（0.09-0.59mg/L）,可溶性有机氮月均浓度的范围为（0.25-0.94mg/L）。铵态氮、硝态氮、可溶性有机氮与总氮间存在显著正相关关系（P〈0.01）。各形态氮浓度的季节规律为冬春高、秋夏低.年氮沉降总量为5.11kg/hm2,其中铵态氮占37.7%、硝态氮占18.8%、可溶性有机氮占43.4%。【结论】雨水中的各形态氮的浓度随着连续降雨逐渐被稀释,在降雨量较大的情况下,各形态氮月均浓度低。各形态氮沉降量均为夏季最高,冬季最低。全年各形态氮45个样品的沉降量与其降雨量之间呈乘幂型相关。

[Objective]The objective of this study was to investigate monthly dynamics of atmos-pheric wet deposition of different forms nitrogen （N）at a suburb site of Kunming,and to quantify the relationships between wet N deposition and precipitation.[Method]In the experimental site, precipitation was sampled by a custom-designed rain collector and daily precipitation was moni-tored by PORTLOG automatic weather station.[Results]The monthly mean concentrations of total dissolved N （DTN）,ammonium （NH4^＋ -N）,nitrate （NO3^- -N）,and dissolved organic N （DON）ranged from 0.54 to 2.60 mg/L,from 0.16 to 1.15 mg/L,from 0.09 to 0.59 mg/L and from 0.25 to 0.94 mg/L,respectively.There was significant linear correlation （P 〈0.01 ）be-tween DTN and NH4^＋ -N,NO3^- -N and DON.Total wet N deposition was 5.1 kg/（hm^2 ·a）,with NH 4^＋ -N,NO3^- -N and DON accounting for 38%,19% and 43%,respectively.[Conclusion]The results suggested that precipitation had a strong dilution effect on N concentrations,with higher concentrations in winter and spring and lower concentrations in autumn and summer.N deposition rate was highest in summer but lowest in winter.The positive relationship between all forms of N and precipitation was fitted well by a power equation.