 |
| Titel |
Coastal hypoxia and sediment biogeochemistry |
| VerfasserIn |
J. J. Middelburg, L. A. Levin |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 6, no. 7 ; Nr. 6, no. 7 (2009-07-28), S.1273-1293 |
| Datensatznummer |
250003913
|
| Publikation (Nr.) |
 copernicus.org/bg-6-1273-2009.pdf |
|
|
|
|
|
| Zusammenfassung |
| The intensity, duration and frequency of coastal hypoxia (oxygen
concentration <63 μM) are increasing due to human alteration of
coastal ecosystems and changes in oceanographic conditions due to global
warming. Here we provide a concise review of the consequences of coastal
hypoxia for sediment biogeochemistry. Changes in bottom-water oxygen levels
have consequences for early diagenetic pathways (more anaerobic at expense
of aerobic pathways), the efficiency of re-oxidation of reduced metabolites
and the nature, direction and magnitude of sediment-water exchange fluxes.
Hypoxia may also lead to more organic matter accumulation and burial and the
organic matter eventually buried is also of higher quality, i.e. less
degraded. Bottom-water oxygen levels also affect the organisms involved in
organic matter processing with the contribution of metazoans decreasing as
oxygen levels drop. Hypoxia has a significant effect on benthic animals with
the consequences that ecosystem functions related to macrofauna such as
bio-irrigation and bioturbation are significantly affected by hypoxia as
well. Since many microbes and microbial-mediated biogeochemical processes
depend on animal-induced transport processes (e.g. re-oxidation of
particulate reduced sulphur and denitrification), there are indirect hypoxia
effects on biogeochemistry via the benthos. Severe long-lasting hypoxia and
anoxia may result in the accumulation of reduced compounds in sediments and
elimination of macrobenthic communities with the consequences that
biogeochemical properties during trajectories of decreasing and increasing
oxygen may be different (hysteresis) with consequences for coastal ecosystem
dynamics. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|