A preliminary carbon budget for a part of the Ems estuary: The Dollard

Abstract

During 1975, measurements were made to quantify all sources of input of organic matter in the Dollard. This made a comparison possible between in situ primary production, import from natural sources and organic waste discharges in terms of organic carbon. In order to make a carbon budget, mineralization and the amount of organic matter buried in the sediment was also measured. Input of organic carbon was mainly based on primary production on the tidal flats (measured in situ as O₂ production, 9.3×10⁶ kg C · year⁻¹), accumulation of suspended matter originating from the North Sea and the River Ems (maximal 37.1×10⁶ kg C · year⁻¹) and discharge of heavily polluted water (33.0×10⁶ kg C · year⁻¹). Input from primary production in the water phase was negligibly low (0.7×10⁶ kg C · year⁻¹). Loss of organic carbon was due to mineralization in the sediment (measured in situ as oxygen consumption, 18.2×10⁶ kg C · year⁻¹), mineralization in the water phase (using the BOD technique, 7.2×10⁶ kg C · year⁻¹) and burying of organic matter in the sediment (9.9·10⁶ kg C · year⁻¹). The loss of dissolved organic matter to the adjacent Waddensea was not measured but must be considerable. Allochthonous detritus was the main source of energy for the food-webs in the Dollard. The role of bacteria as an important source of food for higher organisms in the Dollard is discussed.