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| Titel |
Diagenetic control of nitrogen isotope ratios in Holocene sapropels and recent sediments from the Eastern Mediterranean Sea |
| VerfasserIn |
J. Möbius, N. Lahajnar, K.-C. Emeis |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 7, no. 11 ; Nr. 7, no. 11 (2010-11-30), S.3901-3914 |
| Datensatznummer |
250005078
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| Publikation (Nr.) |
 copernicus.org/bg-7-3901-2010.pdf |
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| Zusammenfassung |
| The enhanced accumulation of organic matter in Eastern Mediterranean
sapropels and their unusually low δ15N values have been
attributed to either enhanced nutrient availability which led to elevated
primary production and carbon sequestration or to enhanced organic matter
preservation under anoxic conditions. In order to evaluate these two
hypothesis we have determined Ba/Al ratios, amino acid composition, N and
organic C concentrations and δ15N in sinking particles, surface
sediments, eight spatially distributed core records of the youngest sapropel
S1 (10–6 ka) and older sapropels (S5, S6) from two locations. These data
suggest that (i) temporal and spatial variations in δ15N of
sedimentary N are driven by different degrees of diagenesis at different
sites rather than by changes in N-sources or primary productivity and (ii)
present day TOC export production would suffice to create a sapropel like S1
under conditions of deep-water anoxia. This implies that both enhanced TOC
accumulation and δ15N depletion in sapropels were due to the absence of
oxygen in deep waters. Thus preservation plays a major role for the
accumulation of organic-rich sediments casting doubt on the need of enhanced
primary production for sapropel formation. |
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