GEOCHEMISTRY OF NITROGEN,PHOSPHORUS AND IRON AT THE WATER-SEDIMENT INTERFACE IN JIAOZHOU BAY

Concentrations of DO, TN, TP, DIN, PO₄-P,and Fe in bottom water,DIN, PO₄-P and Fe in interstitial water and grain size and organic carbon in surface sediments of the Jiaozhou Bay are analyzed. With the exception of NH₄-N, the interstitial water shows NO₃-N concentration 17.8 times,NO₂-N 9.3 times,PO₄-P 12.5 times,and Fe 7.7 times higher than the counterparts of the bottom water. The authors conclude that there is a trend of element releasing from interstitial water into the overlying bottom water. Laterally,concentrations of NO₃-N, NO₂-N, NH₄-N,and PO₄-P in both the interstitial and bottom water as well as Fe in the sediments in the east of the Jiaozhou Bay are higher than those in the west, while the distribution of Fe in both the interstitial and bottom water seems opposed. The results suggest that N, P,and Fe contents in bottom water are mainly controlled by the proximity to the estuary of the east Jiaozhou Bay due to the industrial and agricultural waste discharge and decomposition of marine organism, while the diffusion of the above elements from the interstitial water into the overlying bottom water is significant, and hydrodynamical factor and grain size of sediments should marginally affect the distributions of N, P,and Fe. Moreover, correlation analysis indicates that concentrations of N and P in both bottom and interstitial water are correlated with DO in bottom water,and with organic carbon and Fe in sediments respectively.