Nutrients that fall on the ground from the atmosphere represent a minor component of the total nitrogen (N) input to soils, especially when compared with agricultural, civil and industrial inputs (i.e. sewage treatment plants or sewage systems, fertilizer and manure applications). However, integrating all nitrogen forms, processes and scales can represent a breakthrough challenge for the understanding and the management of the N cycle. A monitoring experiment was set up to collect wet atmospheric depositions in a human-impacted area with multiple land uses, representing different emission sources. Rainwater collection was executed in the surroundings of Milan, in northern Italy, starting from February 2017 to February 2019. The presence of N compounds and their temporal variations in rainwater are consistent with pollution coming from local anthropogenic emission sources of nitrogen oxides and ammonia, mainly related to the use of the heating systems in the cold seasons and the spreading of fertilizers and manure on agricultural fields. Consequently, the total amount of N wet depositions ranges between 14 and about 30 kg/ha yr in the study area. As leaching of N compounds from soils generally increases at deposition rates higher than about 10 kg(N)/ha yr, this work suggests that the N atmospheric input to soils could not be neglected when evaluating the impacts of N sources to terrestrial and aquatic ecosystems, as well as to groundwater resources. This highlights the need of wisely integrating air, soil and water policies for minimising the risk to deteriorate surficial ecosystems and groundwater.

中文翻译：

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受人类高度影响的区域中的大气氮沉积

从大气中掉落到地面的养分占土壤总氮（N）的一小部分，尤其是与农业，民用和工业投入（如污水处理厂或污水处理系统，化肥和肥料应用）相比。但是，整合所有氮的形式，过程和规模对于理解和管理氮循环而言可能是一项突破性挑战。建立了一个监测实验，以收集具有多种土地用途（代表不同排放源）的人为影响区域的潮湿大气沉积物。从2017年2月至2019年2月，在意大利北部米兰的周边地区进行了雨水收集。N化合物的存在及其在雨水中的时间变化与当地人为排放的氮氧化物和氨的污染相一致，这主要与寒冷季节使用供暖系统以及农田上肥料和肥料的传播有关。因此，研究区域中N湿沉降的总量在14至30 kg / ha yr之间。由于通常以高于约10 kg（N）/ ha yr的沉积速率从土壤中淋溶N化合物，因此这项工作表明，在评估N来源对陆地和水生生态系统的影响时，不能忽略土壤中的N大气输入。以及地下水资源。这凸显了明智地整合空气的需求，