Abstract: Benthic nutrient fluxes and early diagentic processes were investigated in the east Chongming tidal flat of Yangtze estuary in winter. 〖JP2〗Significantly nutrient influxes from water column to sediment are observed in high marsh: benthic fluxes of NO-3, NO-2, NH+4, PO3-4 and SiO2-3 are (-0.896±0.540) mmol/m2/d,(-0.089±0.049) mmol/m2/d,〖JP〗(-2.002±0.642) mmol/m2/d,(-0.068±0.006) mmol/m2/d and (-1.334±0.381) mmol/m2/d individually (negative indicate nutrient absorption from water column to sediment and positive indicate nutrient release from sediment to water column). The exflux of NO-3 ((0.203±0.112) mmol/m2/d) and influxes of NO-2 ((-0.010±0.005) mmol/m2/d) and PO3-4 ((-0.005±0.002) mmol/m2/d) are observed in middle marsh. In low marsh, only PO3-4 ((-0.047±0.009) mmol/m2/d) influx is significant and there are large uncertainty in other nutrient fluxes due to strong wave disturbance. Diffusional nutrient fluxes contribute to the benthic nutrient fluxes slightly. Due to benthic flux differences among nutrients, benthic nutrient exchanges promote the growths of N/P and Si/P ratios in water column.

Key words: estuary, salt marsh, east Chongming tidal flat, benthic nutrient fluxes, estuary, salt marsh, east Chongming tidal flat