Characterization and consequences of intermittent sediment oxygenation by macrofauna: interpretation of high-resolution data sets
Abstract
Mineralization of organic matter in marine sediments leads to the depletion of oxygen, while activities of infauna introduce oxygenated seawater to the subsurface. In permeable sediments solutes can be transported from animals and their burrows into the surrounding sediment through advection over several centimeters. The intermittency of pumping leads to a spatially heterogeneous distribution of oxidants, with the temporal dynamics depending on sediment reactivity and activity patterns of the macrofauna. Here, we present results from a series of experiments in which these dynamics are studied at high spatial and temporal resolution using planar optodes. From O2, pH and pCO2 optode data, we quantify rates of O2 consumption and dissolved inorganic carbon production, as well alkalinity dynamics, with millimeter-scale resolution. Simulating intermittent irrigation by imposed pumping patterns in thin aquaria, we derive porewater flow patterns, which together with the production and consumption rates cause the chemical distributions and the establishment of reaction fronts. Our analysis thus establishes a quantitative connection between the locally dynamic redox conditions relevant for biogeochemical transformations and macroscopic observations commonly made with sediment cores.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFM.B51M..05M
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES;
- 0491 Food webs and trophodynamics;
- BIOGEOSCIENCES;
- 0497 Wetlands;
- BIOGEOSCIENCES;
- 4806 Carbon cycling;
- OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL