The principal objective of the proposed research project is to quantify factors influencing the coupling of nitrification and denitrification during early-diagenetic benthic remineralization processes of organic material. The investigation is located in the Baltic and the White Seas, and includes stations which are characterized by different benthic communities and different physical conditions. Field investigations base on various in situ measurements (chamber incubations, microsensors, nitrogen isotope pairing method) to determine concentrations and flux rates of oxygen and nitrogen species at the sediment-water interface and within the sediment.
A combination of the different in situ methods allows an estimation to what extent biological processes e.g. macrofaunal bioturbation influence turnover rates of organic material. In addition the impact of small scale heterogeneity regarding budget calculations of benthic turnover rates of the carbon and nitrogen cycle can be estimated by comparing fluxes deriving from point measurements (microsensors) and fluxes integrating over sediment-compartments (chambers). Results of budget calculations are important to model impacts of anthropogenic activities in coastal areas. As denitrifiction is a main sink within the nitrogen cycle, a detailed understanding of mechanisms driving this process is necessary to assess consequences of anthropogenic induced input, of organic material, nutrients and pollutants into coastal regions.