Nitrogen loading into an urban estuary: Lake Pontchartrain (Louisiana, U.S.A.)

摘要: We constructed a nitrogen loading budget for the Lake Pontchartrain watershed located north of New Orleans, Louisiana (U.S.A.). Water quality measurements, discharge estimates, and literature values were used to establish annual seasonal variations in rates total nitrate. The relatively stable loadings (million kg N) are about 10× that pre-settlement loading, come from atmosphere (1.3), (7.8), pumped urban runoff Orleans (1.0), leakage through Bonnet Carre flood control structure (0.5–0.9). Relatively minor additional amounts fixation Lake. Occasional openings Spillway (for protection) could triple average within 1–2 months. Proposed smaller diversions wetland restoration) raise present N by 50%. results water management, protection restoration may thus have conflicting effects on Lake's phytoplankton community, which is primarily limited. Lowering however, seems quite possible, especially given almost all reducible existing technology, sewerage treatment. analysis demonstrates consequences ecosystem efforts, continued population growth estuarine budgets intertwined with each other, component, changing as policies evolve.