DTU - Biogeochemical implications of coastal anoxia, BioCoast

Project: Research

Project Details

Description

basin Dybet (Mariager Fjord, Denmark) to explore effects of
oxygen depletion on rates and pathways of microbial nitrogen and
carbon cycling.
We will determine rates of key microbial processes at anoxic
depths using a novel oxygen contamination-free in situ incubation
system, and compare these rates to results from parallel
conventional shipboard incubations. This will allow the first
assessment of potential biases associated with conventional
shipboard incubations, which may profoundly influence our
understanding of carbon and nitrogen cycling in anoxic waters,
with important implications for marine biogeochemistry. The
experiments will be supplemented with deliberate oxygen
manipulation experiments for a quantitative assessment of how
oxygen controls carbon and nitrogen cycling across the redoxcline.
Specific questions addressed by our experiments include the
balance between recycling and loss of bioavailable nitrogen, the
effect of oxygen depletion on carbon mineralization kinetics, rates
of dark carbon fixation, and pathways of N2O production. We have
observed a strong oversaturation of N2O in Mariager Fjord and will
deploy a novel in situ N2O sensor to measure distributions at high
spatial resolution as a first step to evaluate the role of Danish
coastal waters as a source of this greenhouse gas.
Experiments will be accompanied by detailed hydrographic,
biogeochemical and community analyses providing a robust
context for generalization to other systems. Thus, the results will
substantially improve our understanding of the biogeochemical
dynamics associated with coastal oxygen depletion, and provide
parameters for predictive modeling of consequences of marine
deoxygenation.
StatusNot started
Effective start/end date01/06/202231/12/2022