基于石生藓类氮含量的贵阳地区大气氮沉降

对贵阳市区到农村地区的石生藓类氮含量进行了系统分析,并根据藓类氮含量(y,%)和大气氮沉降(x, kg hm~(-2) a~(-1))的平均定量关系(y=0.052x+0.7325)计算了各采样点的大气氮沉降值.贵阳地区大气氮沉降的变化范围为0.91～44.69kg hm~(-2) a~(-1),市区大气氮沉降最高平均(29.21±6.17)kg hm~(-2) a~(-1),主要来自城市废水NH3释放;最低平均(11.95±3.95)kg hm~(-2) a~(-1),出现在城市和农村的结合地带,主要原因在于来自市区的氮污染物减少、且大量分布了环城林带、农业活动相对较低;20km以外的农村地区大气氮沉降略微升高(平均(14.31±5.11)kg hm~(-2) a~(-1)),主要反映了农业施肥导致NH3释放的增加.结果表明,石生藓类氮含量是一种经济可靠的大气氮沉降监测工具,能够较准确地量化大气氮沉降的水平,并为深入研究大气氮沉降的生态环境效应提供基础资料.

Quantification of atmospheric nitrogen deposition at Guiyang area based on nitrogen concentration of epilithic mosses

Nitrogen concentration of epilithic mosses from the urban area to rural area at Guiyang was investigated systematically, and the level of atmospheric N deposition at each sampling site was calculated according to the quantitative relationship (y=0.052x+0.7325) between moss N concentration (y,%) and atmospheric N deposition (x, kg hm~(-2) a~(-1)). The level of atmospheric N deposition ranged between 0.91-44.69 kg hm~(-2) a~(-1). The highest value (average (29.21±6.17) kg hm~(-2) a~(-1)) occurred at urban area (0-5km), which was mainly derived from higher NH3 release from city wastewater. The lowest level ((11.95±3.95) kg hm~(-2) a~(-1), 15-30km) at the combining area between the urban and rural area was mainly related to the reduced urban N pollutants, broad distribution of forest belt around the urban and lower agricultural intensity. Slightly higher N deposition ((14.31±5.11) kg hm~(-2) a~(-1)) re-emerged over 20km from the urban center, showing the increase of agricultural NH3 release in rural area caused by fertilizer application. Consequently, N concentration of epilithic mosses was an economic and reliable tool in monitoring atmospheric N deposition, which could exactly quantify the level of atmospheric N deposition and,provide basic information for further studying the ecological and environmental effects of atmospheric N deposition.