The distributions, seasonal variations and influence factors of dissolved iron in the Sanggou bay

Four cruises were carried out in April, August, October 2011 and January 2012 in the Sanggou bay.The concentrations of dissolved iron (DFe) were measured by catalytic kinetic spectrophotometry.The average concentrations of DFe were 3.8 ±0.7 nmml/L, 3.3 ±1.8 nmol/L, 2.6 ±1.0 nmol/L, and 1.8 ±0.6 nmol/L respectively, which showed significant seasonal difference among the four cruises (t-test, p < 0.05, n=19).The distributions of DFe were similar during the study periods, with the high concentrations occupying the estuaries and coastal area, and decreased towards the offshore.A preliminary box model was established to estimate the budgets of DFe for the Sanggou Bay, which demonstrated that the major sources for DFe in the Sanggou bay included the inputs from riverine and groundwater discharge, atmospheric deposition.The main sinks included the output into Yellow Sea and the absorption or accumulation by biological activities.The residence time of DFe in the Sanggou bay is much shorter than the open ocean, which might be related to the special hydrological condition and the absorption concerning aquaculture activities.