Contributions of mobile source emissions to watershed N budgets along an urban to rural gradient

过量的氮（N）是美国大部分河口的一个严重的水质问题，特别是那些发达的沿海流域的下游。虽然氮的主要来源，大气沉降，废水，肥料和其他农业来源是众所周知的，其相对重要性作为氮源，以特定的河口是不。一个问题是，美国大多数研究人员使用的沉积监测网络的设计是为了避免附近来源的影响，如郊区/城市地区。这一点很重要，因为特别是在城市地区，排放的主要来源是机动车辆和建筑设备等移动的来源，其排放的一部分沉积在附近。这项工作将允许更准确地估计氮通量从城市集水区，包括沉积从移动的源排放。作为这项研究的一部分，N预算将构建子流域沿着土地利用梯度从城市核心到农村/郊区边缘的巴尔的摩，考虑到大气N输入的移动的来源的贡献。作为这项研究的一部分，学生将参与收集样本，从收集器放置在整个研究领域的学校与巴尔的摩生态系统研究校园LTER。这项研究的结果将对沿海系统的管理，特别是那些靠近主要城市地区的影响。这一建议是量化一个重要的和以前被忽视的N源对我们的沿海系统的贡献的重要的第一步。由于这种差距，在我们的理解，很难设计一个综合计划来管理N输入河口。这是第一个项目，以考虑移动的源沉积在流域N预算，并与这些估计的两种方法广泛使用的研究人员和管理人员估计沉积（NADP/CASTNet）和排放量（EPA的国家移动的库存模型）。

Excess nitrogen (N) is a serious water-quality problem in most of the estuaries in the US, especially those downstream of developed coastal basins. While the major sources of this N, atmospheric deposition, wastewater, fertilizer, and other agricultural sources are well known, their relative importance as N sources to particular estuaries is not. One trouble is that the deposition monitoring network used by most researchers in the US was designed to avoid influences from nearby sources such as suburban/urban areas. This is significant because a major source of emissions especially in urban areas are mobile sources such as motor vehicles and construction equipment and a portion of their emissions are deposited nearby. This work will allow more accurate estimates of nitrogen fluxes from urban catchments by including deposition from mobile source emissions. As part of this research, N budgets will be constructed for sub-watersheds along a land-use gradient from the urban core to the rural/suburban fringe of Baltimore that take into account the contribution of mobile sources to atmospheric N inputs. As part of this research, students will be involved in collecting samples from collectors placed throughout the study area at schools associated with the Baltimore Ecosystem Study Schoolyard LTER. Results of this study will have implications for the management of coastal systems' especially those near major metropolitan areas. This proposal is an important first step in quantifying the contribution of a significant and previously overlooked source of N to our coastal systems. Because of this gap in our understanding it is difficult to design an integrated plan to manage N inputs to estuaries. This is the first project to consider mobile source deposition in watershed N budgets and to relate these estimates to the two methods widely used by researchers and managers to estimate deposition (NADP/CASTNet) and emissions (EPA's National Mobile Inventory Model).