Ammonia Nitrogen at the Water–Sediment Interface in Puck Bay (Baltic Sea)

Abstract

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 sediment to water. Ammonia flux varied from 5 to 1434 μmol NH 4-N m −2 day −1. In total, c. 138·2 tonneammonia year −1pass from sediments 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 tonne ammonia year −1passes from the sediment to near-bottom water of Puck Bay. In interstitial waters, ammonia occurred in concentrations varying over a wide range (3–1084 μmol NH 4-N dm −3). The basic factors affecting the magnitude of ammonia concentration in interstitial waters included: oxidation of organic matter, type of sediment, and inflow of fresh underground waters to the region examined. This paper involves preliminary studies only and constitutes a continuation of the studies on ionic macrocomponents and phosphorus in interstitial waters of Puck Bay undertaken previously.