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Location of the sediment trap (ST ) and the boxcores ( UM4, UM15, UM35 and ABC39) in the eastern Mediterranean.
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A sediment trap mooring was deployed in the central eastern Mediterranean from November 1991 to August 1994. At 3000 m water depth, total mass, Al, Ca, Mg, Sr and 230Th fluxes recovered by the sediment trap are highly seasonal, with highest fluxes during early spring in 1992 and 1993, and during late-spring/early-summer in 1994. Comparison of histo...
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Context 1
... boxcores, from different water depths and located near the sediment trap, were 2.1.1. Sediment trap Two 1 m2 sediment traps ( Technicap PPS5/2) analysed ( Fig. 1; Table 2). The tops of UM4, UM15 and UM35 contained an oxic, light-brown were deployed in a time series in the southwestern Bannock Basin (34°18∞N, 20°01∞E; Fig. 1). This ooze, which overlay a red-brown, oxidized zone. A double manganese peak, indicative of a burn- basin is filled with a brine below 3150 m water depth (Fig. 2). The ...
Context 2
... boxcores, from different water depths and located near the sediment trap, were 2.1.1. Sediment trap Two 1 m2 sediment traps ( Technicap PPS5/2) analysed ( Fig. 1; Table 2). The tops of UM4, UM15 and UM35 contained an oxic, light-brown were deployed in a time series in the southwestern Bannock Basin (34°18∞N, 20°01∞E; Fig. 1). This ooze, which overlay a red-brown, oxidized zone. A double manganese peak, indicative of a burn- basin is filled with a brine below 3150 m water depth (Fig. 2). The upper trap was located at down front ( Thomson et al., 1995;Van Santvoort et al., 1996), was found in all three cores. Below 3000 m water depth, well above the sea ...
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... The surface chlorophyll concentrations are highest during the late winter-early spring convective mixing period, lowest during the summer months [21], generally remaining below 0.5 mg L −1 in the open sea [22,23]. During winter and spring, the combined effect of the two westerly upper air jet streams namely the polar front jet stream and the subtropical jet stream, result in the east-southeast propagation of subtropical cyclones which outcomes in the fertilization of Mediterranean water by Saharan dust [24], while most of the atmospheric deposition in the Mediterranean Sea occurs as wet deposition [25]. lation, atmospheric input from Sahara with high N/P (100:1), and limited denitrification [26,27]. ...
This study is the first attempt to understand the coccolith flux and its seasonal variability at the deepest part of the Mediterranean Sea. Samples were obtained from the deepest Mediterranean time-series sediment trap (4300 m) moored in the SE Ionian Sea (Nestor site) from January 2015 to November 2017. Throughout the study period, the coccolith fluxes displayed a seasonality signal with high values during the late winter-early spring convective mixing period (February to April) and low flux values during summer except for some solitary peaks in June. The maximum coccolith flux was observed in March 2015 while the minimum value was recorded in November 2017. Among the nineteen identified species of heterococcoliths, the dominant species in all the samples was Emiliania huxleyi reaching up to 79%, followed by Florisphaera profunda that comprised up to 33% of the total coccolith count. For the annual cycle of 2015, the average coccolith flux for the Nestor Site at a relatively shallower depth (2000 m) was comparable and for some time intervals was lower than the coccolith flux recorded in the present study at 4300 m, while coccolith flux peaks appeared simultaneously in both traps indicating a fast sinking rate. The higher E. huxleyi, F. profunda, Gladiolithus flabellatus, and Calciosolenia brasiliensis coccolith flux at 4300 m compared with their corresponding fluxes at 2000 m can be attributed to lateral advection, resuspension, and/or the influence of Eastern Mediterranean Deep Waters (EMDWs).
... Contributors of carbon export have been studied extensively, and often sediment traps are used as a tool (Pejrup et al., 1996;Rutten et al., 2000). Taxonomic identification of the trapped particles is usually analyzed under the microscope or using HPLC for pigment composition Z. Zhang et al., 2015). ...
Flux and efficiency of carbon export in the ocean has been widely studied using sediment traps, but due to limitations of traditional methods, differential contribution of different organisms is poorly understood. Here, we used DNA metabarcoding to document taxonomic composition for sediment traps deployed at a continental shelf (C6) and a continental slope (C9) site in the South China Sea. The results indicated that metazoans (mainly copepods) and dinoflagellates were the most dominant contributors overall, while dinoflagellates, diatoms, and haptophytes dominated the photosynthetic assemblage. For prokaryotes, Gammaproteobacteria dominated all samples. Furthermore, comparing the trap flora to overlying plankton revealed that metazoans and Polycystinea from Eukaryota and Gammaproteobacteria and Bacteroidetes from Prokaryota were enriched in the trap at both stations whereas haptophytes and Dinophyceae were consistently attenuated during sinking. In addition, Oceanospirillaceae and Rhodobacteraceae exhibited negative correlations with dinoflagellates, and based on overlying plankton metatranscriptomes, were most transcriptionally active lineages for metabolizing labile and semi‐labile organic carbon, potentially contributing to the Martin's decay of sinking particulate organic carbon. Using DNA and RNA sequencing technologies, this study provides novel insights into the lineage‐specific contribution and dynamic impacts of microbes to carbon export in a subtropical marginal sea.
... Today, deposition of Saharan dust is a dominant (> 90%) detrital component to sediments in the Eastern Mediterranean basin (Guerzoni et al., 1999), and its distribution is approximately uniform in an east-west direction (Krom et al., 1999a;Rutten et al., 2000). Compared to EMS surface sediments, representing typical arid climate conditions, sapropel S5 samples have a distinctly lower 87 Sr/ 86 Sr and a slightly higher ε Nd isotopic composition (Figs. 2 and 6). ...
... Moreover, the irregularly active river/wadi systems can provoke turbid flows associated with high detrital fluxes into the Ionian Sea (Weldeab et al., 2002a; Zielhofer et al., 2008). Saharan dust is the dominant source of the EMS detrital sediment (~25e100 Mt/yr) (see compilations in Goudie and Middleton, 2001), notably for the Ionian Sea receiving low riverine input (Guerzoni et al., 1997; Rutten et al., 2000). Dust from the northern and eastern EMS borderlands is quantitatively negligible (Guerzoni et al., 1997; Ehrmann et al., 2007a). ...
... Titanium and Zr mainly reside in heavy minerals and can be transported with coarse quartz in wind-blown Saharan materials (see Scheuvens et al., 2013). At present, riverine supplies to the central Mediterranean are low compared to eolian fluxes (Guerzoni et al., 1997; Rutten et al., 2000). Using Sr and Nd isotopes, it has been shown that minor amounts of Nile sedimentsdif anydmay be deposited in the areas west of Crete (Krom et al., 1999a; Weldeab et al., 2002a) (c.f. ...
Hydroclimate variability has exerted a fundamental control on the alternating deposition of organic-lean marl and organic-rich sapropel sediments in the eastern Mediterranean Sea (EMS). However, the exact mechanisms regarding the freshwater sources and related changes are still debated. Here, Sr and Nd isotopes and high-resolution elemental data are used to constrain different riverine and eolian supplies to the central Mediterranean over the past 9.8 ka. The detrital sediments in core CP10BC, taken at the margin of the Libyan shelf in the southwestern Ionian Sea, can be described by a three-endmember mixing system based on Sr and Nd isotopic compositions. The same systematics can also be deduced from Ti and K compositional variability. The endmembers comprise: Saharan Dust, Aegean/Nile, and Libyan Soil, representing the eolian supply from North Africa, the riverine inputs from the Aegean/Nile areas, as well as the riverine and shelf-derived fluxes from the Libyan-Tunisian margin, respectively. For the sapropel S1 period in particular, we find important detrital supplies from fossil river/wadi systems along the Libyan-Tunisian margin, activated by intensified African monsoon precipitation. Combining the temporal profiles with the consistent variability observed in the ⁸⁷Sr/⁸⁶Sr–1000/Sr diagram, such Libyan contribution has been most prominent during the uppermost period of sapropel S1 in core CP10BC. This observation is in agreement with hydroclimate reconstructions of northwestern Libya. Comparison of the Sr-Nd isotope data between core CP10BC and four cores taken along a west–east transect throughout the EMS shows that this detrital supply originated mainly from western Libya/Tunisia, and was transported as far eastward as ∼25°E while being diluted by an increasing Nile contribution.
... Rothwell et al. (2006) and Thomson et al. (2004) report Sr/Ca peaks in Mediterranean sediments as indicating high Sr aragonite requiring shallow-water source, and Rothwell et al. (2006) describe pelagic intervals containing abundant pteropods registering high Sr/Ca. This may be texturally-related artefact considering reports that pteropod shells in E Mediterranean are low-Sr aragonite (Krinsley and Bieri 1959;Kinsman 1969;Rutten et al. 2000) Applications and literature ...
XRF core scanners represent a major innovation in the analysis of cored sediment sequences and have revolutionised palaeoenvironmental research over the last decade. Such scanners provide capability to rapidly and non-destructively record element proxy variations at decadal, annual and even sub-annual scales. Their use, initially by the marine science community, was soon taken up by lake core researchers, particularly after the advent of high-resolution models incorporating x-radiography, particularly suited for analysis of varved sequences. Their impact on the environmental sciences is seen in the exponential rise in research papers published since 2005 involving their use. Although their main application has been in the study of Quaternary marine and lake cores, they have also been used in the analysis of terrestrial hard rock cores in mining applications, analysis of loess cores, speleothems, cores from peat bogs and river banks and cores collected for environmental forensics and pollution studies. Further, an important cohort of papers has addressed interpretation and calibration issues, increasing the robustness of acquired datasets. In this paper we review marine and lacustrine applications of XRF core scanning, together with environmental forensics applications and research into data optimisation and calibration presented in the current volume. We provide synopses of the principal findings and a concise summary of the current work.
... Comparison with recent and modern varved pelagic and hemipelagic sediments (e.g. Bull and Kemp, 1995;Thunnell et al., 1995;Kemp et al., 2000;Rutten et al., 2000) suggests that the alternation of biogenic and terrigenous laminae observed in whitish packets (Fig. 4A, B) records seasonal variations of the quantity and composition of the sediments delivered to the basin floor (red curve, Fig. 11). Terrigenous laminae may reflect the humid season, when precipitation and runoff were greatest; biogenic whitish laminae deposited during the high productive less humid season, following episodes of phytoplankton bloom in the upper photic water layers, fuelled by nutrients influxes (Thunnell et al., 1995). ...
... Comparison with recent and modern varved pelagic and hemipelagic sediments (e.g. Bull and Kemp, 1995;Thunnell et al., 1995;Kemp et al., 2000;Rutten et al., 2000) suggests that the alternation of biogenic and terrigenous laminae observed in whitish packets (Fig. 4A, B) records seasonal variations of the quantity and composition of the sediments delivered to the basin floor (red curve, Fig. 11). Terrigenous laminae may reflect the humid season, when precipitation and runoff were greatest; biogenic whitish laminae deposited during the high productive less humid season, following episodes of phytoplankton bloom in the upper photic water layers, fuelled by nutrients influxes (Thunnell et al., 1995). ...
The recognition of peculiar laminated layers atypically rich in a biogenic intrabasinal component in the mudstone intervals from the Messinian (late Miocene) Primary Lower Gypsum unit (5.97-5.60 Ma) of the Piedmont basin (NW Italy) provides information on the palaeoenvironmental evolution at precessional insolation maxima. These cyclic layers consist of irregular alternation of cm-thick grey terrigenous laminae and whitish composite packets; the latter is in turn composed of sub mm-thick wrinkled dolomite-rich laminae that alternate with terrigenous ones. Two types of layers can be distinguished: i) peloidal layers, composed of faecal pellets and irregular diatom-rich aggregates, interpreted as marine snow floccules; ii) filament bearing layers, composed of interwoven filaments up to 150 μm across, corresponding to remains of Beggiatoa-like giant sulphide-oxidizing bacteria. By comparison with present-day settings, the peloidal layers are interpreted as flocculent layers, deposited on anoxic sea bottoms, following episodes of phytoplankton bloom in the upper water column. The filament-bearing layers are considered as chemotrophic microbial mats, growing on dysaerobic sea bottoms. The uncommon preservation of both kinds of layers is the result of extensive dolomite precipitation in the shallow subsurface, induced by bacterial sulphate reduction. The laminated layers are the first reported example of a high frequency climate-driven cyclicity in the non-evaporitic portion of the Primary Lower Gypsum unit. Their stacking pattern within the mudstone intervals reflects the gradual increase of the oxygen content of bottom waters during the humid precessional hemicycle, culminating with gypsum deposition at the onset of the arid phase.
... As a consequence, the marine vertical export flux in the Northwestern Mediterranean Sea is strongly dependent on climatic and meteorological conditions as well. Therefore, the understanding of the interannual/decadal variability of vertical export fluxes of elements in relation with climatic and meteorological changes requires (i) reliable measurements of vertical export fluxes, including the use of proxies such as 234 Th and 230 Th to minimize possible bias in the measurements (Rutten et al., 2000;Roy-Barman et al., 2009), and (ii) good knowledge of physical (climatic and meteorological) parameters that determine the magnitude of dense water formation, as well as their interannual/decadal variability (Stabholz et al., 2013). This is important in terms of ongoing global change, because any alteration of the climatic/meteorological conditions would significantly impact the marine vertical export flux, and this would ultimately determine the evolution of metal cycling in the Northwestern Mediterranean, independently from changes in the atmospheric (metal) deposition. ...
... Previous studies on biogenic fluxes in the eastern Mediterranean are mostly related to their chemical composition (carbonate vs. silica) and report on the abundance of the main planktonic groups (Boldrin et al., 2002; De Lazzari et al., 1999; Socal et al., 1999; Turchetto et al., 2012), but without a detailed quantification of the contribution from the different species. Specific assessments of coccolithophore sinking assemblage composition and seasonal variations have been performed in several coastal settings offshore Crete (Malinverno et al., 2009; Triantaphyllou et al., 2004 ), while for the pelagic environment, the only study performed up to now refers to the Bannock Basin area (34°18′N, 20°01′E, i.e. Rutten et al., 2000;). To date, little is known about seasonal/interannual variations of diatom assemblages from the pelagic eastern Mediterranean, due to their secondary role in the total primary production of this basin. ...
... Very strong seasonal variations characterize the total particle flux pattern during the investigated time interval. The average total particle flux (23 and 15 mg m −2 day −1 at 500 and 2800 m, respectively) is close to the values recorded at the nearby Bannock Basin location at 3000 m (16 mg m −2 day −1 (i.e. Rutten et al., 2000) and in open areas of the north-western Mediterranean (i.e. offshore Corsica: 22 mg m −2 day −1 , Miquel et al., 1994) and 1–2 orders of magnitude lower than what is found in other areas of the Mediterranean, influenced by coastal proximity and/or bottom transport, (De Lazzari et al., 1999; Fabres et al., 2002; Heussner and Monaco, 1996; Heussner et al., , 2006 Kerhervé et al., 1999 Kerhervé et al., , 2001 Malinverno et al., 2009; Miserocchi et al., 1999; Sanchez-Vidal et al., 2004; Stavrakakis et al., 2000; Sternberg et al., 2007 ). ...
... Previous estimates of total particle sinking speed indicate similar values for the northern Ionian Sea (N140 m day −1 , i.e. Boldrin et al., 2002) but much lower values for the nearby Bannock Basin location (17–25 m day − 1 for coccoliths and lithogenic particles, i.e. Rutten et al., 2000;). However, the latter estimates are not based on the correlation of fluxes from different depths but rather on the calculation of the time lag between biogenic fluxes at 3000 m and the timing of satellite-sensed sea surface Chl-a maxima and may therefore suffer some biases. ...
... The terrigenous solid-phase fluxes can potentially originate from re-sedimentation of shelf sediments, and from input by local and by more remote (Adriatic) riverine systems, all of which are influenced by prevailing current directions and strengths (see Section 2: Regional setting). In addition, a minor eolian (Saharan) contribution is possible: for the present day, 2/3 of the terrigenous fluxes to the central Ionian Sea sediments have been reported to result from eolian dust (e.g., Correggiari et al., 1989;Rutten et al., 2000). This eolian dust flux is equivalent to a sedimentation rate of~10 mm/ka (Rutten et al., 2000) which is negligible compared to the total sedimentation rate of 600 mm/ka in our study area, the Gulf of Taranto (Fig. 2). ...
... In addition, a minor eolian (Saharan) contribution is possible: for the present day, 2/3 of the terrigenous fluxes to the central Ionian Sea sediments have been reported to result from eolian dust (e.g., Correggiari et al., 1989;Rutten et al., 2000). This eolian dust flux is equivalent to a sedimentation rate of~10 mm/ka (Rutten et al., 2000) which is negligible compared to the total sedimentation rate of 600 mm/ka in our study area, the Gulf of Taranto (Fig. 2). Therefore, we will not further discuss this option. ...
An extensive, high-resolution, sedimentological–geochemical survey was done using geo-acoustics, XRF-core scans, ICP-AES, AMS 14C-dating and grain size analyses of sediments in 11 cores from the Gulf of Taranto, the southern Adriatic Sea, and the central Ionian Sea spanning the last 16 cal. ka BP. Comparable results were obtained for cores from the Gallipoli Shelf (eastern Gulf of Taranto), and the southern Adriatic Sea suggesting that the dominant provenance of Gallipoli Shelf sediments is from the western Adriatic mud belt. The 210Pb and 14C-dated high-accumulation-rate sediments permit a detailed reconstruction of climate variability over the last 16 cal. ka BP.
