SENSEflux-USGLB: Nitrogen and Phosphorus Loads, Sources and Pathways

SENSEflux-USGLB, the Spatially Explicit Nutrient Source Estimate and Flux for the United States Great Lakes Basin estimates total annual nitrogen and phosphorus loads from the US Great Lakes Basin to the coastline, as well as sources and pathways at 120 meter resolution for an average year during 2008 - 2015 period (ca. 2010). The SENSEflux model uses a GIS and mass balance approach to simulate nutrient fate and transport from point and nonpoint sources across the landscape through rivers to lakes and wetlands. It includes four components: (1) nutrient applications, (2) in situ losses, (3) basin attenuation through surface and subsurface pathways, and (4) stream and lake attenuation. This resource includes 120-meter maps of nitrogen and phosphorus loads, mass balance components (total applied nutrient, crop harvest, basin loss, river uptake, soil and groundwater storage), sources (atmospheric deposition, chemical agricultural fertilizer, chemical nonagricultural fertilizer, manure, septic tanks, nitrogen fixation from legumes, and point sources) and pathways (overland flow, tile drainage, groundwater, septic plumes, point) along with corresponding watershed summaries at the Hydrologic Unit Code 12 (HUC12) and HUC8 levels, as defined in the USGS 2014 Watershed Boundary Dataset. Sources are separated by subsurface (groundwater flow and septic plumes within groundwater) pathway and surface (overland and tile fields) pathway, so total nutrient delivery through a specific nutrient source can be computed as the sum of each source (i.e., gQAgComm + sQAgComm) through the pathways if applicable. Watershed summaries (kg/day) derived from those 120-meter maps (kg/day/cell) using the zonal statistics method with the 'SUM' function. SENSEflux-USGLB is described in full detail in the manuscript and supporting information of Wan et al. (2023) \"Important Role of Overland Flows and Tile Field Pathways in Nutrient Transport in Environmental Science & Technology. https://doi.org/10.1021/acs.est.3c03741.

美国五大湖流域空间显性养分源估算与通量数据集（SENSEflux-USGLB）旨在估算2008-2015年（约2010年）平均年份下，美国五大湖流域向海岸线输送的年度总氮、总磷负荷，并以120米分辨率刻画其养分来源与运移路径。SENSEflux模型采用地理信息系统（Geographic Information System, GIS）与质量平衡方法，模拟景观尺度上点源与非点源养分的归宿与运移过程，经河流最终汇入湖泊与湿地。该模型包含四大组分：（1）养分施用强度；（2）原位养分损失；（3）地表与地下路径下的流域养分衰减；（4）河流与湖泊养分衰减。本数据集包含120米分辨率的氮、磷负荷图，以及质量平衡组分图（包括总施用养分、作物收获量、流域养分损失、河流摄取量、土壤与地下水储量）、养分来源（包括大气沉降、农用化肥、非农用化肥、粪肥、化粪池、豆科植物固氮以及点源）与运移路径（包括地表径流、暗管排水、地下水、化粪池羽流、点源路径），同时附带基于美国地质调查局（United States Geological Survey, USGS）2014年流域边界数据集所定义的水文单元代码12级（HUC12）与8级（HUC8）尺度的对应流域汇总数据。养分来源按地下路径（地下水流动与地下水中的化粪池羽流）与地表路径（地表径流与暗管田块）分别归类，因此若有需要，可通过对应路径下各来源的通量之和（例如gQAgComm + sQAgComm）计算特定养分来源的总输送量。流域汇总数据单位为千克/日，其通过对120米分辨率栅格图（单位：千克/日/栅格）采用分区统计工具的“求和（SUM）”函数计算得到。该数据集的详细信息可参见Wan等人（2023）发表于《环境科学与技术》（Environmental Science & Technology）的论文及其补充材料，论文标题为《地表径流与暗管田块路径在养分运移中的重要作用》，DOI链接：https://doi.org/10.1021/acs.est.3c03741。