Geochemical evidence for high-resolution variations during deposition of the Holocene S1 sapropel on the Cretan Ridge, Eastern Mediterranean

Gennari, Giordana; Tamburini, F.; Ariztegui, Daniel; Hajdas, Irka; Spezzaferri, Silvia

doi:10.1016/j.palaeo.2008.06.007

Cited by 15 publications

(7 citation statements)

References 56 publications

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“…B.P. ), which was deposited during the Early Holocene climate optimum, has been the subject of extensive study [e.g., de Lange et al , 2008; Gennari et al , 2009; Meier et al , 2004; Negri and Giunta , 2001]. An increasingly warmer and wetter climate at the start of the Holocene triggered an increased discharge of freshwater and nutrients from the Nile, which could have resulted in water column stratification and the formation of bottom water anoxia [e.g., de Lange et al , 2008; Emeis et al , 2003; Rohling , 1989], but an enhanced primary production and OM transport also must have played a role in the accumulation of C org ‐rich sapropels [ Calvert , 1983; de Lange and ten Haven , 1983].…”

Section: Introductionmentioning

confidence: 99%

Exploring preserved fossil dinoflagellate and haptophyte DNA signatures to infer ecological and environmental changes during deposition of sapropel S1 in the eastern Mediterranean

et al. 2011

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[1] In this study we used a comparative multiproxy survey (fossil DNA, calcareous nannofossils, and lipid biomarkers) to test whether preserved genetic signatures provide an accurate view of haptophyte and dinoflagellate populations during deposition of the eastern Mediterranean sapropel S1 and the organic carbon-depleted oxidized marls flanking the S1 and to see if we could identify important environmental indicator species that did not fossilize and escaped previous microscopic identification. The marls above and below the S1 contained low concentrations of lipid biomarkers diagnostic for dinoflagellates and haptophytes (i.e., dinosterol and long-chain alkenones), but 500 base pair long ribosomal DNA fragments of these protists were below the detection limit. In contrast, dinoflagellate and haptophyte DNA could be recovered from the organic carbon-rich S1, but the most abundant sequences did not represent species that were part of the nannofossil (this study) or previously described dinocyst composition. The oldest section of S1 (9.8 to ∼814 C kyr B.P.) revealed a predominance of dinoflagellate phylotypes, which were previously only detected in anoxic Black Sea sediments. In the same section of the core, the most abundant haptophyte sequence showed highest similarity with uncultivated haptophytes that were previously shown to grow mixotrophically as predators of picocyanobacteria, an adaptation that promotes growth in oligotrophic marine waters. Sequences with highest similarities to clones found in marine surface waters predominated in the S1 after ∼8 14 C kyr B.P. We discuss whether the shifts in haptophyte and dinoflagellate populations inferred from the preserved DNA reflect known environmental changes that occurred during the formation of sapropel S1.

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Section: Introductionmentioning

confidence: 99%

Exploring preserved fossil dinoflagellate and haptophyte DNA signatures to infer ecological and environmental changes during deposition of sapropel S1 in the eastern Mediterranean

et al. 2011

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“…Röhl and Abrams 2000;2001;Brauer et al 2008a). Latest generation core scanners provide spatial resolutions down to 100 µm but, depending on the focussing device of the µ-XRF instrument, the spot size can be narrowed down to as little as 50 µm (Haug et al 2003;Haschke 2006;Brauer et al 2007aBrauer et al , 2008aGennari et al 2009). Typical spot sizes applied for sediment core analyses vary between 0.5 mm (Yancheva et al 2007) and a few cm (Richter et al 2001).…”

Section: Introductionmentioning

confidence: 99%

Combined µ-XRF and Microfacies Techniques for Lake Sediment Analyses

Dulski

Brauer

Mangili

2015

Micro-XRF Studies of Sediment Cores

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This contribution presents an evaluation of still unexplored potentials, limitations and technical details of µ-XRF element scanning particularly for varved sediment analyses using the vacuum device EAGLE III XL. For this case study a 33 cm long interval of exceptionally well-preserved sub-millimetre scale calcite varves of the interglacial lake deposits from Piànico has been selected. In addition to the demonstration of the very good repeatability of XRF element scans, one focus of this paper is on discussing a suitable scanner resolution in terms of a compromise between short analyses times and a resolution that allows capturing the geochemical signature even of seasonal sub-layers. By combining scanner data with microscopic sediment inspection geochemical signatures of various micro-facies as, for example, varves, detrital layers and matrix-supported and clay layers are explored. The potential of counting varves using the seasonal signature of specific elements is discussed and potential error sources are disclosed by comparison with microscopic varve counts. Detailed grid-µXRF-scanning provides for the first time an insight into the internal structure of varves presented as high-resolution 3D-images. Finally, an approach of calibrating scanner data through comparison with ICP-MS analyses is introduced. Sensitivity factors for each element have been defined as ratios between mean count rates and bulk element concentrations.

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“…Nowadays, solar cycle influence on sediment records is under debate because the above variabilities are also present in the modern climate records. In recent years, several periodicities have been identified in major elements levels (Dean et al 2004;Gennari et al 2009;Shanahan et al 2009). It has also been recently shown, in processes involved in sapropel formation (Gennari et al 2009), that the solar activity could affect not only the sedimentation rate but also the chemical composition of the sediment.…”

Section: Introductionmentioning

confidence: 99%

Cyclic influences on the heavy metal chronology in a Central Mediterranean area (Palermo Gulf, Italy)

et al. 2010

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PurposeThe evaluation of long-term heavy metal concentrations in the Gulf of Palermo (Italy) has been carried out in order to investigate how changes of pollution levels in the last 50 years can be reflected in marine sediments. Measurements of Cr, Cu, Hg, Pb, and Zn concentrations were performed on dated fractions of a sediment core. Time series analysis has allowed to obtain information on the chronology of the heavy metal pollution of the area and to identify seasonal components and trends.Materials and methodsHeavy metal concentrations in the <63 μm fraction of core sections were obtained by Atomic Absorption Spectrophotometry, after wet sieving, drying, and digestion procedures. Dating of sediment core had been previously achieved by excess 210Pb method. A methodological approach based on the time series analysis was used in order to investigate the presence of heavy metal cyclic variations and to outline the trend of each pollutant. A spectral analysis was performed on concentration data to investigate the presence of seasonal components. The additive component model, widely used to estimate seasonal and long-term behavior, was chosen for the time series analysis. R statistical software and advanced toolkits have been used.Results and discussionSediment core has been found to provide information for years from 1959 to 2004. Time series analysis results showed the presence of statistically significant cycles, of about 10.3, 7.2, and 4.8 years. Seasonal components of heavy metals concentrations and well known cycles have been compared. In particular, correlations with seasonal components of Sun Spot Number Cycle, Multivariate ENSO Index, and Winter North Atlantic Oscillation Index have been investigated. Moreover, the presence of trends in heavy metal concentration data has been highlighted.ConclusionsTime series analysis on the concentrations of heavy metals from a dated sediment core sampled in the Palermo Gulf (Italy) has been carried out. Cyclical pattern over a time of about 50 years have been identified thanks to spectral analysis. Statistically significant cycles have been detected, showing how metal concentrations in sediments also depend on natural cycles. Seasonal and trend components have been extracted, through time series decomposition by the LOESS procedures. Seasonal components of our data and of natural cycles show a good agreement in terms of series correlations. Sediment core, on a local scale and with good reliability, records the dynamics of heavy metal pollution of the area, also allowing comparisons on a much larger scale

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Geochemical evidence for high-resolution variations during deposition of the Holocene S1 sapropel on the Cretan Ridge, Eastern Mediterranean

Cited by 15 publications

References 56 publications

Exploring preserved fossil dinoflagellate and haptophyte DNA signatures to infer ecological and environmental changes during deposition of sapropel S1 in the eastern Mediterranean

Exploring preserved fossil dinoflagellate and haptophyte DNA signatures to infer ecological and environmental changes during deposition of sapropel S1 in the eastern Mediterranean

Combined µ-XRF and Microfacies Techniques for Lake Sediment Analyses

Cyclic influences on the heavy metal chronology in a Central Mediterranean area (Palermo Gulf, Italy)

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