We developed a simple model that related NO3export to point-source N loading and nonpoint source Nloads from chemical fertilizers and NOy deposition andtested it at the global scale using data from 35 largerivers with a global distribution. The model explainedwell( r2 > 0.8 ) the nearly 1000-fold variation in NO3export from different regions of the world. The modelsuggests that human activity is the dominant control ofNO3 export even though less than 20 of the 100 Tg N yr2added to land in fertilizer and NOy deposition is atpresent exported from rivers as NO3. Watershed exportto rivers may increase in the future due to eitherincreased loads to the watershed or decreased watershedretention. Simple models, coupled with continuedmeasurements of NO3 in rivers, will be of use ininterpreting these regional changes.
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机译：我们开发了一个简单的模型，将NO3出口与化肥和NOy沉积的点源氮负荷和非点源氮负荷相关联，并使用来自全球的35个更大生产国的数据在全球范围内对其进行了测试。该模型很好地解释了（r2> 0.8）来自世界不同地区的NO3出口变化了将近1000倍。这些模型建议即使在肥料中添加到土地的100 Tg N yr2中不到20吨Ny2目前从河流中以NO3的形式出口，人类活动仍是NO3出口的主要控制。流域向河流的流域出口将来可能会由于流域负荷增加或流域保留减少而增加。简单的模型，加上对河流中NO3的持续测量，将可用于解释这些区域变化。
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