Stream chemistry for watershed 263 (urban) sites BES ID 579-

In the Baltimore urban long-term ecological research (LTER) project, (Baltimore Ecosystem Study, BES) we use the watershed approach to evaluate integrated ecosystem function. The LTER research is centered on the Gwynns Falls watershed, a 17,150 ha catchment that traverses a gradient from the urban core of Baltimore, through older urban residential (1900 - 1950) and suburban (1950- 1980) zones, rapidly suburbanizing areas and a rural/suburban fringe. Our long-term sampling network includes four longitudinal sampling sites along the Gwynns Falls as well as several small (40 - 100 ha) watersheds located within or near to the Gwynns Falls. The longitudinal sites provide data on water and nutrient fluxes in the different land use zones of the watershed (rural/suburban, rapidly suburbanizing, old suburban, urban core) and the small watersheds provide more focused data on specific land use areas (forest, agriculture, rural/suburban, urban). Each of the gaging sites is continuously monitored for discharge and is sampled weekly for chemistry. Additional chemical sampling is carried out in a supplemental set of sites to provide a greater range of land use. Weekly analyses includes nitrate, phosphate, total nitrogen, total phosphorus, chloride and sulfate, total suspended solids, turbidity, fecal coliforms, temperature, dissolved oxygen and pH. Cations, dissolved organic carbon and nitrogen and metals are measured on selected samples. This dataset is for Watershed 263, a 364 ha urban storm drain watershed (or sewershed), with 30,000 residents with mixed industrial, institutional, and residential land uses. In March 2004, we established long-term monitoring sites in two sub-watersheds within W283. Both are approximately 17 ha, with 20% impervious surface and 4% vegetation cover. Samples (weekly grab and flow-weighted composite) are taken in a stormwater drainage pipe.巴尔的摩城市长期生态研究（Long-Term Ecological Research, LTER）项目（又称巴尔的摩生态系统研究（Baltimore Ecosystem Study, BES））中，我们采用流域系统方法开展综合生态系统功能评估。该长期生态研究以甘恩斯瀑布（Gwynns Falls）流域为核心，这片面积达17150公顷的集水区，其土地利用梯度覆盖巴尔的摩城市核心区、1900-1950年建成的老旧城市居住区、1950-1980年建成的郊区、快速郊区化区域以及乡村/郊区边缘地带。 我们的长期采样网络包含沿甘恩斯瀑布布设的4个纵向采样点，以及若干位于甘恩斯瀑布流域内部或邻近的40-100公顷小型子流域。纵向采样点可提供该流域不同土地利用分区（乡村/郊区、快速郊区化区域、老旧郊区、城市核心区）的水体与养分通量数据，而小型子流域则可针对特定土地利用类型（森林、农业用地、乡村/郊区、城市区域）提供更聚焦的观测数据。每个水文监测站点均持续监测径流量，并每周采集水样开展化学分析。此外，我们还在补充采样点位开展额外化学采样，以覆盖更广泛的土地利用类型。每周检测指标涵盖硝酸盐、磷酸盐、总氮、总磷、氯化物、硫酸盐、总悬浮物、浊度、粪大肠菌群、水温、溶解氧及pH值。部分选定水样还会检测阳离子、溶解性有机碳、溶解性有机氮以及金属元素。 本数据集对应263号流域（Watershed 263），该流域面积364公顷，为城市雨水管流域（或称污水流域），区内居住人口30000人，土地利用类型为工业、公共设施与住宅混合用地。2004年3月，我们在W283的两个子流域内设立了长期监测点位。两个子流域面积均约为17公顷，不透水面占比20%，植被覆盖率为4%。采样方式为在雨水排水管道中采集每周单次瞬时水样与流量加权混合水样。