摘要
我们制定了一种简单的模型,将硝酸盐(NO_3)输出与点源氮负荷和来自化学肥料和氮氧化物(NO_y)沉降的非点源氮负荷联系起来,并利用分布于全球的35条大河流得出的数据对模型进行全球规模的检验。该模型对世界不同地区近千倍变化的硝酸盐输出作了良好的解释(r^2>0.8)。此模型说明人类活动是硝酸盐输出的主要控制因子,即使现在每年100Tg N中只有不到20Tg N是施到土地的肥料和氮氧化物沉降物以硝酸盐形态由河流输出的。将来,流域向河流输出的硝酸盐量有可能增加,因为对流域的负荷增加或者流域的氮滞留减少。简单的模型,与河流中硝酸盐连续测量相结合,将用来对这些区域变化做出解释。
We developed a simple model that related NO3 export to point-source N loading and nonpoint source N loads from chemical fertilizers and NO, deposition and tested it at the global scale using data from 35 large rivers with a global distribution. The model explained well (r2>0.8) the nearly 1000-fold variation in NO3 export from different regions world. The model suggests that human activity is the dominant control of NO3 export ever though less than 20 of the 100 Tg N yr-1 added to land in fertilizer and NO, deposition at present exported from rivers as NO3. Watershed export to rivers may increase in future due to either increased loads to the watershed or decreased watershed retention Simple models, coupled with continued measurements of NO3 in rivers, will be of use in interpreting these regional changes.
