The evaluation of nitrogen (N) removal in aquatic ecosystems within human exploited watersheds may allow the setting of upper limits of N use in agriculture. However, such an evaluation is complex owing to the small scale heterogeneity of aquatic ecosystems, including dominant vegetation and inherent N-related processes. In this work, microbial denitrification and primary producer assimilation were estimated in fluvial wetlands and irrigation canals of the Mincio River watershed (~ 850 km², Italy), and scaled-up to the whole watershed using GIS and remote-sensing techniques. Denitrification in the fluvial wetland area which covered only ~ 3% of the watershed was estimated to permanently remove 80% of the excess N, defined as N soil surplus (~ 5500 t N y⁻¹) minus N river export (~ 1300 t N y⁻¹). Adding the estimated N uptake by primary producers in the wetland system, approximately all the N excess produced in adjacent agricultural land of the Mincio watershed can be retained or removed by internal processes. In contrast, the canal network had a linear extent of over 1770 km but its estimated denitrification capacity was comparatively much smaller (up to 7% of the excess N). Combinations of N-budgeting at the whole basin scale, experimental data, GIS and remote sensing techniques offer the possibility to analyze N retention capacity in heterogeneous aquatic environments. The application of such approach to the Mincio watershed stresses the functional relevance of even small wetland areas in agricultural settings.

中文翻译：

---

河流湿地和斑驳的农业流域中的灌溉渠的氮去除工艺升级

对人类开发的流域内水生生态系统中氮（N）去除的评估可以确定农业中氮的使用上限。然而，由于水生生态系统的小规模异质性，包括优势植被和与氮有关的固有过程，这种评估是复杂的。在这项工作中，对Mincio河流域（〜850 km ²，意大利）的河流湿地和灌溉渠中的微生物反硝化作用和主要生产者同化进行了估算，并使用GIS和遥感技术将其扩大到整个流域。估计仅覆盖约3％流域的河流湿地地区的反​​硝化作用将永久去除80％的过量N，这被定义为N土壤剩余（约5500 t N y ^-1）减去北河流量（〜1300 t N y ^-1）。加上湿地系统中初级生产者的估计氮吸收量，Mincio流域相邻农田中生产的几乎所有氮过量都可以通过内部过程保留或清除。相比之下，渠道网络的线性范围超过1770公里，但其估计的反硝化能力相对要小得多（最多为过量氮的7％）。整个流域尺度上的氮肥预算，实验数据，GIS和遥感技术的结合为分析非均质水生环境中的氮保留能力提供了可能性。这种方法在Mincio流域中的应用强调了在农业环境中即使是很小的湿地地区的功能相关性。