Print PageExcess nitrogen (N) is a serious water-quality problem in most of the estuaries in the US. A first step in addressing this problem is to quantify the fluxes of N in coastal watersheds. This typically involves constructing input-output N budgets in which a single estimate of N deposition (usually from the nearest NADP/CASTNet site) is used. However, recent studies have documented that a portion of the emissions from mobile sources (cars and trucks, construction equipment, planes, boats, etc) is deposited near where they are produced potentially resulting in an underestimate of N inputs in urban areas. In this study we assessed this variability by measuring throughfall N deposition using mixed bed ion exchange resins in urban, suburban, agricultural and forested watersheds, along a 30 km urban-rural land use gradient in Baltimore Md.
Results/Conclusions
Deposition was the lowest (9.65 ± 0.5 kg N ha (-1) y(-1) in the completely forested watershed. It was ~28% higher in the suburban watershed (12.40 ± 0.75 kg N ha (-1) y(-1) and 54% higher in the urban (14.62 ± 0.87 kg N ha(-1) y(-1)) and agricultural (14.88 ± 1.0 kg N ha (-1) y(-1) watersheds. These differences need to be taken into account when constructing watershed N budgets especially in urban coastal areas.
