Darwin Harbour is a macrotidal estuary located in the wet–dry tropics of Northern Australia. This largely unmodified oligotrophic harbour is also a working port, where the largest proportion of the Northern Territory population reside and future industrial and urban development are planned. A contemporary examination of nitrogen sources and loading is presented to aid further evaluation of this pressure and infer some of important mechanisms that drive the nutrient status of this estuarine system. Nitrogen inputs as total nitrogen (TN) from watersheds and point-sources, predominantly wastewater treatment plants (WwTP), were modelled for 2007 and 2017 to provide a decadal evaluation of N loads in alignment with the generation of revised regional land use. The model was applied to 21 sub-catchments that have been subject to expanding urbanisation since 2007. Nitrogen yields ranged from 3 kg N ha/y to 23 kg N ha/y increasing with the proportion of urbanisation in the catchment. Comparison between 2007 and 2017 showed that riverine, watershed and point-source inputs had increased by 40% coinciding with urban expansion. Wet season rainfall was a primary means of nitrogen transport, and variability of climate and land use interact to amplify riverine N exports, with urbanisation an important agent of change influencing the contribution of terrestrially derived sources of nitrogen. The last of which contributed approximately 5%–10% of N inputs to the estuary, but was outweighed by oceanic sources (>90%). Current water quality condition and nitrogen limitation of estuarine waters suggests mechanisms, such as watershed nitrogen retention and biogeochemical cycling, particularly denitrification, in receiving waters and sediments remain active despite oceanic inputs and increasing anthropogenic loads.

达尔文港（Darwin Harbour）是一个潮汐河口，位于北澳大利亚的干湿热带地区。这个大体上未经改造的贫营养港也是一个工作港口，北领地人口占最大比例，并且计划未来的工业和城市发展。提出了当代氮源和负荷的检查方法，以帮助进一步评估该压力并推断出一些重要的机制，以驱动该河口系统的营养状况。对流域和点源，主要是废水处理厂（WwTP）的氮输入作为总氮（TN）进行了建模，以针对2007年和2017年进行十年的N负荷评估，以适应修订后的区域土地使用的产生。该模型已应用于自2007年以来一直在扩展城市化进程的21个子集水区。随着集水区中城市化比例的增加，氮的产量范围从3 kg N ha / y到23 kg N ha / y。2007年与2017年之间的比较显示，河流，流域和点源的投入与城市扩张相吻合而增长了40％。湿季降雨是氮素运输的主要手段，气候和土地利用的可变性相互影响，从而增加了河流氮素的输出，而城市化进程是影响陆生氮源贡献的重要变化因子。其中最后一个贡献了河口N投入的5％–10％，但远超过海洋来源（> 90％）。当前的水质状况和河口水的氮限制提示了其机理，