The impact of sedimentary alkalinity release on the water column CO<sub>2</sub> system in the North Sea
It has been previously proposed that alkalinity release from sediments can play an important role in the carbonate dynamics on continental shelves, lowering the <i>p</i>CO<sub>2</sub> of seawater and hence increasing the CO<sub>2</sub> uptake from the atmosphere....
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-02-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/13/841/2016/bg-13-841-2016.pdf |
| Summary: | It has been previously proposed that alkalinity release from sediments can
play an important role in the carbonate dynamics on continental shelves,
lowering the <i>p</i>CO<sub>2</sub> of seawater and hence increasing the CO<sub>2</sub> uptake
from the atmosphere. To test this hypothesis, sedimentary alkalinity
generation was quantified within cohesive and permeable sediments across the
North Sea during two cruises in September 2011 (basin-wide) and June 2012
(Dutch coastal zone). Benthic fluxes of oxygen (O<sub>2</sub>), alkalinity
(<i>A</i><sub>T</sub>) and dissolved inorganic carbon (DIC) were determined using
shipboard closed sediment incubations. Our results show that sediments can
form an important source of alkalinity for the overlying water, particularly
in the shallow southern North Sea, where high <i>A</i><sub>T</sub> and DIC fluxes
were recorded in near-shore sediments of the Belgian, Dutch and German
coastal zone. In contrast, fluxes of <i>A</i><sub>T</sub> and DIC are substantially
lower in the deeper, seasonally stratified, northern part of the North Sea.
Based on the data collected, we performed a model analysis to constrain the
main pathways of alkalinity generation in the sediment, and to quantify how
sedimentary alkalinity drives atmospheric CO<sub>2</sub> uptake in the southern North
Sea. Overall, our results show that sedimentary alkalinity generation should
be regarded as a key component in the CO<sub>2</sub> dynamics of shallow coastal
systems. |
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| ISSN: | 1726-4170 1726-4189 |