AMMONIA NITROGEN AT THE WATER-SEDIMENT INTERFACE IN PUCK BAY (BALTIC SEA)

The magnitude of the exchange flux at the water-sediment interface was determined on the basis of the ammonia concentration gradient at the near-bottom water-interstitial interface and Fick's first law. It was established that in Puck Bay, ammonia almost always passes from the se diment to water. Ammonia flux varied from 5 to 1434 mu mol NH4-N m(-2) day(-1). In total, c. 138.2 tonne ammonia year(-)1 pass from sediment s of Internal Puck Bay to near-bottom water, the equivalent value for External Puck Bay being 686.9 tonne year(-1). In total, about 825 tonn e ammonia year(-1) passes from the sediment to near-bottom water of Pu ck Bay. In interstitial waters, ammonia occurred in concentrations var ying over a wide range (3-1084 mu mol NH4-N dm(-3)). The basic factors affecting the magnitude of ammonia concentration in interstitial wate rs included: oxidation of organic matter, type of sediment, and inflow of fresh underground waters to the region examined. This paper involv es preliminary studies only and constitutes a continuation of the stud ies on ionic macrocomponents and phosphorus in interstitial waters of Puck Bay undertaken previously. (C) 1996 Academic Press Limited