Biogeochemistry

, Volume 89, Issue 2, pp 221–238

Sulphate, dissolved organic carbon, nutrients and terminal metabolic products in deep pore waters of an intertidal flat

  • Melanie Beck
  • Olaf Dellwig
  • Jan M. Holstein
  • Maik Grunwald
  • Gerd Liebezeit
  • Bernhard Schnetger
  • Hans-Jürgen Brumsack
Original Paper

DOI: 10.1007/s10533-008-9215-6

Cite this article as:
Beck, M., Dellwig, O., Holstein, J.M. et al. Biogeochemistry (2008) 89: 221. doi:10.1007/s10533-008-9215-6

Abstract

This study addresses deep pore water chemistry in a permeable intertidal sand flat at the NW German coast. Sulphate, dissolved organic carbon (DOC), nutrients, and several terminal metabolic products were studied down to 5 m sediment depth. By extending the depth domain to several meters, insights into the functioning of deep sandy tidal flats were gained. Despite the dynamic sedimentological conditions in the study area, the general depth profiles obtained in the relatively young intertidal flat sediments of some metres depth are comparable to those determined in deep marine surface sediments. Besides diffusion and lithology which control pore water profiles in most marine surface sediments, biogeochemical processes are influenced by advection in the studied permeable intertidal flat sediments. This is supported by the model setup in which advection has to be implemented to reproduce pore water profiles. Water exchange at the sediment surface and in deeper sediment layers converts these permeable intertidal sediments into a “bio-reactor” where organic matter is recycled, and nutrients and DOC are released. At tidal flat margins, a hydraulic gradient is generated, which leads to water flow towards the creekbank. Deep nutrient-rich pore waters escaping at tidal flat margins during low tide presumably form a source of nutrients for the overlying water column in the study area. Significant correlations between the inorganic products of terminal metabolism (NH4+ and PO43−) and sulphate depletion suggest sulphate reduction to be the dominant pathway of anaerobic carbon remineralisation. Pore water concentrations of sulphate, ammonium, and phosphate were used to elucidate the composition of organic matter degraded in the sediment. Calculated C:N and C:P ratios were supported by model results.

Keywords

Intertidal flatPore waterSulphateNutrientsDOCGeochemistry

Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  • Melanie Beck
    • 1
  • Olaf Dellwig
    • 1
    • 2
  • Jan M. Holstein
    • 3
  • Maik Grunwald
    • 1
  • Gerd Liebezeit
    • 4
  • Bernhard Schnetger
    • 1
  • Hans-Jürgen Brumsack
    • 1
  1. 1.Research Group Microbiogeochemistry, Institute for Chemistry and Biology of the Marine Environment (ICBM)Carl von Ossietzky UniversityOldenburgGermany
  2. 2.Leibniz Institute for Baltic Sea Research IOWRostockGermany
  3. 3.Research Group Mathematical Modelling, Institute for Chemistry and Biology of the Marine Environment (ICBM)Carl von Ossietzky UniversityOldenburgGermany
  4. 4.ICBM-TerramareWilhelmshavenGermany