Radiocarbon, stable isotopic compositions and seawater chemical properties of Black Sea core-top sediments and CTD stations

DOI

Chloropigments and their derivative pheopigments preserved in sediments can directly be linked to photosynthesis. Their carbon and nitrogen stable isotopic compositions have been shown to be a good recorder of recent and past surface ocean environmental conditions tracing the carbon and nitrogen sources and dominant assimilation processes of the phytoplanktonic community. In this study we report results from combined compound-specific radiocarbon and stable carbon and nitrogen isotope analysis to examine the time-scales of synthesis and fate of chlorophyll-a and its degradation products pheophytin-a, pyropheophytin-a, and 132,173-cyclopheophorbide-a-enol until burial in Black Sea core-top sediments. The pigments are mainly of marine phytoplanktonic origin as implied by their stable isotopic compositions. Pigment ?15N values indicate nitrate as the major uptake substrate but 15N-depletion towards the open marine setting indicates either contribution from N2-fixation or direct uptake of ammonium from deeper waters. Radiocarbon concentrations translate into minimum and maximum pigment ages of approximately 40 to 1200 years. This implies that protective mechanisms against decomposition such as association with minerals, storage in deltaic anoxic environments, or eutrophication-induced hypoxia and light limitation are much more efficient than previously thought. Moreover, seasonal variations of nutrient source, growth period, and habitat and their associated isotopic variability are likely at least as strong as long-term trends. Combined triple isotope analysis of sedimentary chlorophyll and its primary derivatives is a powerful tool to delineate biogeochemical and diagenetic processes in the surface water and sediments, and to assess their precise time-scales.

Identifier
DOI https://doi.org/10.1594/PANGAEA.758107
Related Identifier References https://nbn-resolving.org/urn:nbn:de:gbv:46-diss000119049
Related Identifier References https://doi.org/10.5194/bg-7-4105-2010
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.758107
Provenance
Creator Kusch, Stephanie ORCID logo; Kashiyama, Y ORCID logo; Ogawa, Nanako O ORCID logo; Altabet, Mark A ORCID logo; Butzin, Martin ORCID logo; Friedrich, Jana; Ohkouchi, Naohiko ORCID logo; Mollenhauer, Gesine (ORCID: 0000-0001-5138-564X)
Publisher PANGAEA
Publication Year 2011
Rights Creative Commons Attribution 3.0 Unported; https://creativecommons.org/licenses/by/3.0/
OpenAccess true
Representation
Resource Type Publication Series of Datasets; Collection
Format application/zip
Size 4 datasets
Discipline Earth System Research
Spatial Coverage (29.191W, 43.981S, 31.514E, 45.078N); Black Sea; NW Black Sea
Temporal Coverage Begin 2008-03-11T16:16:00Z
Temporal Coverage End 2008-03-21T10:05:00Z