Modeling the response of water quality in the Seine River Estuary to human activity in its watershed over the last 50 years

摘要: The unique database of water quality measurements made in the Seine estuary over 45 years by Service de la Navigation at Rouen is used here to reconstruct evolution oxygen status and nutrient fluxes Bight during last half century. Riverstrahler model establish link between these long-term trends functioning system agricultural, domestic, industrial activity watershed this period taking into account natural man-induced hydrological variations. Oxygenation fluvial sector below Paris has increased considerably owing improved wastewater treatment, but a large part remains completely anoxic spring summer months. Nitrogen input surface waters from urban sources remained essentially constant while diffuse inputs agricultural soils have 5-fold as result more intensive practices well loss retention capacity riparian zones. Phosphorus domestic 3-fold 1950 1980, decreased gradually recent years. generally high level phosphorus contamination favored strong algal development all tributaries River upstream paris since 1960s. Silica inputs, originating mainly weathering rocks, fluctuate widely depending on hydrology. In-stream silica, linked diatom blooms, limited. These changes induced several shifts limitation conditions Bight.