氮和磷污染是水生生物和人类福祉的重要问题。虽然这些营养素大部分应用于景观,对营养素应用之间复杂的相互作用知之甚少,传输衰减过程,和沿海负荷。这里,我们增强和应用空间显式营养源估算和通量模型(SENSEflux)来模拟从美国大湖盆地到海岸线的年度总氮和磷负荷,确定营养输送热点,并在高分辨率(120米)下估计不同来源和路径的相对贡献。除了在流吸收之外,该模型的主要新颖之处在于SENSEflux明确描述了通过四种不同途径的养分衰减,而这些途径在其他模型中很少共同描述:来自瓷砖排水的农田的径流,陆上径流,地下水流量,和地下水中的化脓液。我们的分析表明,农业来源在向大湖区输送的总氮(TN)(58%)和总磷(TP)(46%)中占主导地位。此外,这项研究表明,表面途径(陆流和瓷砖田地排水的总和)主导着养分输送,将66%的TN和76%的TP负荷运输到美国大湖海岸线。重要的是,这项研究提供了第一个全流域范围内的非感染性地下水(TN:26%;TP:5%)和化粪池地下水(TN:4%;TP:2%)向湖泊输送养分的估计。这项工作为环境管理者提供了有价值的信息,以减少五大湖的营养负荷。可以转移到全球其他面临类似营养素管理挑战的地区。
Nitrogen and phosphorus pollution is of great concern to aquatic life and human well-being. While most of these nutrients are applied to the landscape, little is known about the complex interplay among nutrient applications, transport attenuation processes, and coastal loads. Here, we enhance and apply the Spatially Explicit Nutrient Source Estimate and Flux model (SENSEflux) to simulate the total annual nitrogen and phosphorus loads from the US Great Lakes Basin to the coastline, identify nutrient delivery hotspots, and estimate the relative contributions of different sources and pathways at a high resolution (120 m). In addition to in-stream uptake, the main novelty of this model is that SENSEflux explicitly describes nutrient attenuation through four distinct pathways that are seldom described jointly in other models: runoff from tile-drained agricultural fields, overland runoff, groundwater flow, and septic plumes within groundwater. Our analysis shows that agricultural sources are dominant for both total nitrogen (TN) (58%) and total phosphorus (TP) (46%) deliveries to the Great Lakes. In addition, this study reveals that the surface pathways (sum of overland flow and tile field drainage) dominate nutrient delivery, transporting 66% of the TN and 76% of the TP loads to the US Great Lakes coastline. Importantly, this study provides the first basin-wide estimates of both nonseptic groundwater (TN: 26%; TP: 5%) and septic-plume groundwater (TN: 4%; TP: 2%) deliveries of nutrients to the lakes. This work provides valuable information for environmental managers to target efforts to reduce nutrient loads to the Great Lakes, which could be transferred to other regions worldwide that are facing similar nutrient management challenges.