Nutrient Transformation and Retention by Coastal Prairie Wetlands, Upper Gulf Coast, Texas

摘要

Coastal prairie wetlands (CPWs) are small, rain-fed depressions and flats that, together with their catchments, occupy approximately 40 % of the landscape around Galveston Bay, Texas, USA. Many CPWs are unregulated because they are perceived as "isolated" and a significant nexus has not been established. Results from sampling of precipitation and surface water of 12 CPWs revealed that CPWs had lower concentrations of nitrate- nitrogen (mean 18 μg L~(-1)) than precipitation (342 μg L~(-1)). A similar trend was observed for ammonia-N. Organic nutrient concentrations were several times higher in wetlands than in precipitation. Based on water budgets for six CPWs, net annual nutrient export rates indicate that CPWs are strong sinks for inorganic N and P; moderate sinks for organic N and P, and sources of dissolved organic carbon. Capture, storage, transformation, and pulsed releases of nutrients to Galveston Bay and its tributaries emphasize the role of CPWs in regulating water quality on a landscape scale. These finding demonstrate a nexus with navigable waters.