Core Depth Research Articles

PNS48 DEVELOPMENT OF A BRIEF, GENERIC, MODULAR RESOURCE-USE MEASURE: QUALITATIVE INTERVIEWS WITH HEALTH ECONOMISTS

In healthcare studies, participants often complete resource-use measures (RUMs). RUMs are often adapted on a study-by-study basis, with limited psychometric testing. This study undertook qualitative interviews with experienced health economists to test the usability, face validity and content validity of a newly developed RUM (ModRUM). ModRUM is a brief, generic RUM with a core module (6 questions) on healthcare use and modules to increase depth and breadth. A purposeful sampling strategy was used to recruit health economists with recent experience of implementing RUMs. Health economists were sent two versions of ModRUM (core module and depth extension). During telephone interviews, pre-defined questions on the relevance, clarity, conciseness, and omission of items were asked. Audio-recordings were transcribed and transcripts coded. Analysis drew on methods of constant comparison, where participants’ comments were continually compared to identify common themes. Findings were discussed with the research team, who decided whether ModRUM should be adapted or the suggestion should be explored with patients. Ten health economists from the United Kingdom were interviewed (mean duration: 44 minutes). Common themes emerged for the core module, with most questions considered adequate. Feedback on depth questions varied on whether more, less or alternative detail should be captured. For example, many thought it was inadequate to group community-based non-GP healthcare professionals in one question. ModRUM was revised to incorporate suggested changes agreed by the research team, including for example, an option to pre-specify numerous non-GP healthcare professionals. Our aim is to develop a well-validated, brief, generic RUM, which is needed to increase comparability of health economic research. In previous work, we used consensus methods to identify items and develop ModRUM. In this work, we used qualitative methods to enhance the usability and validity of ModRUM. Our findings in this study suggest that we are closer to achieving a valid measure.

Authigenic formation of Ca–Mg carbonates in the shallow alkaline Lake Neusiedl, Austria

Abstract. Despite advances regarding the microbial and organic-molecular impact on nucleation, the formation of dolomite in sedimentary environments is still incompletely understood. Since 1960, apparent dolomite formation has been reported from mud sediments of the shallow, oligohaline and alkaline Lake Neusiedl, Austria. To trace potential dolomite formation or diagenetic alteration processes in its deposits, lake water samples and sediment cores were analyzed with respect to sediment composition, hydrochemistry and bacterial community composition. Sediments comprise 20 cm of homogenous mud with 60 wt % carbonate, which overlies dark-laminated consolidated mud containing 50 wt % carbonate and plant debris. Hydrochemical measurements reveal a shift from oxic lake water with pH 9.0 to anoxic sediment pore water with pH 7.5. A decrease in SO42- with a concomitant increase in ΣH2S and NH4+ from 0 to 15 cm core depth indicates anaerobic heterotrophic decomposition, including sulfate reduction. The bacterial community composition reflects the zonation indicated by the pore water chemistry, with a distinct increase in fermentative taxa below 15 cm core depth. The water column is highly supersaturated with respect to (disordered) dolomite and calcite, whereas saturation indices of both minerals rapidly approach zero in the sediment. Notably, the relative proportions of different authigenic carbonate phases and their stoichiometric compositions remain constant with increasing core depth. Hence, evidence for Ca–Mg carbonate formation or ripening to dolomite is lacking within the sediment of Lake Neusiedl. As a consequence, precipitation of high-magnesium calcite (HMC) and protodolomite does not occur in association with anoxic sediment and sulfate-reducing conditions. Instead, analytical data for Lake Neusiedl suggest that authigenic HMC and protodolomite precipitate from the supersaturated, well-mixed aerobic water column. This observation supports an alternative concept to dolomite formation in anoxic sediments, comprising Ca–Mg carbonate precipitation in the water column under aerobic and alkaline conditions.

Deeper Than Expected: The Finding of a Remarkable Ancient Harbour at Gadir/Gades and an Exceptional Sedimentary Archive (Cádiz, Southern Spain)

Geoarchaeological cores were retrieved in the centre of the old “Bahia-Caleta” palaeochannel located between the Erytheia and Cotinusa islands in the former Cadiz archipelago, in present-day southern Spain. The unprecedented coring depth (~ 35–50 m) allowed us to identify the bottom of a Phoenician–Punic and Roman harbour. Located at 20–40 m b.s.l. in the sedimentary sequence, silty sand deposits reveal a deep semi-protected shelter with abundant ceramic and archaeobotanical findings. Based on these new results, the palaeotopography of the islands of Cadiz is reinterpreted, demonstrating the presence of a harbour accessible from the west and possibly from the east until (at least) the Roman period. This major discovery opens meaningful perspectives for archaeological, geomorphological and palaeoenvironmental research.

Mineralogical and geochemical characterisation of alkaline lake sediments to trace origin, depositional processes, and anthropogenic impacts: Inle Lake (Southern Shan State, Myanmar)

Southeast Asia contains a major portion of wetland areas of international significance, but only 14% of these wetlands are under protection. Inle Lake is the second largest freshwater body in Myanmar and the most important for its environmental, economic, and agricultural values. However, the lake is seriously threatened by anthropic activities as they are dramatically decreasing its open water surface. While water-quality studies have assessed the presence of nutrients and contaminants, little is known about the sediment quality. Therefore, the overall objective of the present study was to analyse the natural sedimentation patterns and the anthropogenic disturbances in this lake. To this end, both grab and core sediments were investigated by combining mineralogical, morphological, and geochemical analyses, and their composition was compared to the composition of rocks and soil from the watershed. Mineralogical data indicate that sediment samples collected at or near the main inflow, and at the outflow show a lower abundance (about 43%) of calcite, which generally increases with depth in sediment cores, reaching more than 90% in the centre of the lake. Lower calcite contents correspond to higher percentages of other minerals. These findings allow us to clearly distinguish the allogenic (quartz, mica/illite, kaolinite, and detrital calcite) from the endogenic (mostly calcite) minerals, as confirmed by the soil and rock mineralogy. The origin of the mineral contents at the different sites is further supported by the observation of the grain morphology and composition. The most abundant metal in the lake sediments is Ca, in agreement with the high calcite content. Following in order of abundance are Al, Fe, and K, which are connected to the detrital input to the lake. In the rock and soil samples, the most abundant trace element is Mn, which is significantly correlated with many other trace elements (e.g., Co, Cr, Cu, Ni, V, Zn, and As), suggesting their common lithogenic origin. Similarly, in the lake sediments, the trace elements Co, Cr, Cu, Ni, Pb, V, Zn, and As display fairly homogenous concentration ranges, in the order of tens of ppm, and are strongly correlated with the detrital minerals (mica, kaolinite, and quartz) and negatively correlated with the calcite content. The mineralogical and elemental distribution in the lakebed area and with depth in the sediment cores allowed us to identify the increased soil and bedrock erosion as a major anthropogenic impact to the lake. The sedimentation disturbance is especially evident at the main inflow, the Nanlit stream, which has caused the development of a large alluvial fan, visible in satellite images. This large sediment input is likely to have accelerated the decrease in open water surface and in depth of this shallow lake. Additionally, when the measured concentrations of Potentially Toxic Elements were compared to consensus-based Sediment Quality Guidelines (SQGs), it was shown that As, Cr, Cu, Ni, Pb, and Zn often exceeded the threshold effect concentration (TEC), and that Cr, Ni, and Pb sometimes exceeded the probable effect concentration (PEC). On the other hand, Enrichment Factors (EFs), calculated with respect to soils of the watershed, showed minimal enrichment and indicated that the potential toxicity effect was primarily a result of detrital sedimentation outpacing carbonate sedimentation. Sediment characterisation allowed us to obtain a better understanding of lake dynamics and environmental impacts, which is fundamental in achieving effective management and maintenance of the ecological character of Inle Lake, in line with the objective set by the Ramsar Convention for wetlands of international relevance.

Examining bulk and iron-associated organic carbon through depth in margin sea sediments (China) under contrasting depositional settings: Chemical and NEXAFS spectral characterization

Abstract Marine sediments are the largest sink for organic carbon (OC) on Earth, and iron (Fe) oxides play an important role in stabilization of sedimentary OC. However, the roles of Fe oxides in OC stabilization during prolonged burial, for example, up to tens of thousands of years or more are still poorly constrained. In this study, we used traditional chemical extraction and near-edge X-ray absorption fine structure (NEXAFS) spectroscopic technique to characterize bulk OC and Fe-associated OC (Fe-OC) through depth in gravity cores collected from three sites near the Yangtze River Estuary (YRE), in the South Yellow Sea (SYS), and in the middle Okinawa Trough, which have contrasting depositional environments. Results show that depositional environments have exerted quite different influences on sources and burial of sedimentary OC, and thus on OC degradation during prolonged burial at the three sites. Reactive Fe (FeR) contents at the three sites are greatly influenced by sediment sources, the history of its transport, and its reworking intensity, with FeR contents near the highly dynamic YRE much higher than at the central SYS and the middle Okinawa Trough. The fractions of Fe-OC in total OC (fFe-OC) displayed no clear or consistent trends with depth or by site, probably due to the dual roles of Fe redox cycling in OC protection versus its oxidation. As indicated by the fFe-OC, reactive Fe plays a limited role in OC preservation in margin sea sediments of East China. A combination of NEXAFS spectra and isotopic compositions of bulk OC and Fe-OC indicates that main OC functionalities have not experienced differential alterations and/or no specific OC moieties have been selectively stabilized/released during prolonged burial in the three contrasting depositional environments.

Identification of magnetic minerals in peatland at the section of DD REP B 693 lake Diatas using XRD (X-ray Diffraction)

Volcanic ash is dispersed into the air when an eruption occurs, whilst the magma that reaches the surface of the Earth cools to form igneous rocks before eventually breaking down to form sedimentary rocks. One of the places where the sedimentation of volcanic ash occurs following eruptions are peatlands. This study aims to determine the type of magnetic minerals contained in the peat at Lake Diatas. The identity of the magnetic minerals was determined using the X-Ray Diffraction method. The samples used in this study are taken based on depth of the peat core where a value of magnetic susceptibility had been measured previously. The results of the x-ray diffraction analysis for each sample obtained are the diffraction angle (2θ), distance between fields (dhkl ), diffraction intensity (I) and relative intensity. Data from this measurement are then compared with magnetic mineral data bases in order to identify the identity of the magnetic minerals within the peat. Analysis of the results obtained using X-Ray Diffraction indicate the identity of the magnetic minerals in the peat samples at Lake Diatas. The dominant type of magnetic mineral is magnetite (Fe3O4), along with othermagnetic mineralssuch as hematite. Magnetite diffracts at 18.3773°, 30.9888°, 31.5036°, 53.6169°, 65.7656°, 78.6261°, hematite at 65.9474°, 75.1103°, 78.8619°, while non-magnetic minerals such as quartz diffracts at 28.0575°, 28.2029°, 52.4150°.

Molecular and stable isotopic evidence for anaerobic ammonium-oxidizing bacteria in tidal flow constructed wetlands

The process of anaerobic ammonium oxidation (anammox) plays a significant part in global nitrogen cycling, yet its depth-specific distribution and importance in tidal flow constructed wetlands (TF CWs) remained unclear. Currently, the abundance, biodiversity, vertical distribution, rates and potential role of the anammox process in two TF CWs of the Yangtze Estuary, China, were explored. The results indicated that anammox bacteria were widely distributed in the TF CWs, and Candidatus Brocadia was the dominant group among the anammox genera. The widespread presence of the anammox bacteria was observed at different water depths of the soil cores, and the abundance of total bacterial 16S rRNA and hzsB genes was 4.47–20.08 × 109 and 0.81–5.91 × 105 copies per gram of dry soil (copies g−1 ds), respectively. The homogenized soils were incubated with stable nitrogen isotope to confirm the rates of anammox in the TF CWs, and the anammox activities were 2.38–6.72 nmol of N2 per gram of dry soil per day (nmol N2 g−1 dry soil d−1), with contributions of 2.7–7.5% nitrogen gas production and anammox that was more active in the deeper layer of the two TF CWs.

Re-investigating Miocene age control and paleoenvironmental reconstructions in western Amazonia (northwestern Solimões Basin, Brazil)

The modern Amazonian rainforest has a great fascination and global significance, but our knowledge of past landscape changes is still limited due to sparse data and the lack of radiometric age constrains. Precise dating in records older than the late Pleistocene are difficult to obtain and often regionally confined, therefore biostratigraphic correlations are used to estimate depositional ages across sedimentary basins. Aiming for a better understanding of the Neogene changes in western Brazil, we studied palynology and ostracod assemblages from the Solimões Formation, a key site for paleoenvironmental models to discuss the biotic changes in Amazonia. Further, we compare the biostratigraphic information of both groups with radiometric maximum deposition ages constrained by U/Pb measurements on detrital zircon grains.Down to the depth of ~95 m, zircon populations show a maximum deposition age of 11.42 ± 0.66 Ma documenting Tortonian (late Miocene) or younger ages for the top of the Solimões Formation. Palynological biostratigraphy show the Psilatricolporites caribbiensis zone (latest Miocene–Pliocene) down to a depth of 181.8 m, where the Grimsdalea magnaclavata zone suggests a late middle Miocene to early late Miocene age. In comparison, ostracod biostratigraphy indicates the Cyprideis cyrtoma zone (late Miocene) down to 176.0 m and the Cyprideis minipunctata (late middle to late Miocene) for the bottom of the section. Thus, both biostratigraphic concepts suggest ages close to the maximum ages indicated by the detrital zircons. This comparison of the biozonations with U/Pb maximum deposition ages represents the first independent calibration of these widely used methods for age determination in the Solimões Basin.Palynological and ostracod data illustrate dynamic environments varying from fluvial settings with wetland forests and swamps to lakes and/or abandoned channels with temporary slightly saline conditions. Instead of a slow evolution of Neogene Amazonian environments, our results show migrating rivers and waterbodies surrounded by rainforest during the period recorded by the base and top of the studied core material, separated by a phase of more extensive lakes and swamps (core depth 90–120 m). Indicators for slightly elevated salinity are found until the topmost sample and thus persisted during the late Miocene.This highlights the importance of new age control to improve the regional biostratigraphic timescale and reconstructed environmental changes.

Visualizing Microbial Community Dynamics via a Controllable Soil Environment.

Understanding the basic biology that underpins soil microbiome interactions is required to predict the metaphenomic response to environmental shifts. A significant knowledge gap remains in how such changes affect microbial community dynamics and their metabolic landscape at microbially relevant spatial scales. Using a custom-built SoilBox system, here we demonstrated changes in microbial community growth and composition in different soil environments (14%, 24%, and 34% soil moisture), contingent upon access to reservoirs of nutrient sources. The SoilBox emulates the probing depth of a common soil core and enables determination of both the spatial organization of the microbial communities and their metabolites, as shown by confocal microscopy in combination with mass spectrometry imaging (MSI). Using chitin as a nutrient source, we used the SoilBox system to observe increased adhesion of microbial biomass on chitin islands resulting in degradation of chitin into N-acetylglucosamine (NAG) and chitobiose. With matrix-assisted laser desorption/ionization (MALDI)-MSI, we also observed several phospholipid families that are functional biomarkers for microbial growth on the chitin islands. Fungal hyphal networks bridging different chitin islands over distances of 27 mm were observed only in the 14% soil moisture regime, indicating that such bridges may act as nutrient highways under drought conditions. In total, these results illustrate a system that can provide unprecedented spatial information about interactions within soil microbial communities as a function of changing environments. We anticipate that this platform will be invaluable in spatially probing specific intra- and interkingdom functional relationships of microbiomes within soil.IMPORTANCE Microbial communities are key components of the soil ecosystem. Recent advances in metagenomics and other omics capabilities have expanded our ability to characterize the composition and function of the soil microbiome. However, characterizing the spatial metabolic and morphological diversity of microbial communities remains a challenge due to the dynamic and complex nature of soil microenvironments. The SoilBox system, demonstrated in this work, simulates an ∼12-cm soil depth, similar to a typical soil core, and provides a platform that facilitates imaging the molecular and topographical landscape of soil microbial communities as a function of environmental gradients. Moreover, the nondestructive harvesting of soil microbial communities for the imaging experiments can enable simultaneous multiomics analysis throughout the depth of the SoilBox. Our results show that by correlating molecular and optical imaging data obtained using the SoilBox platform, deeper insights into the nature of specific soil microbial interactions can be achieved.

Microplastics in sediment cores as indicators of temporal trends in microplastic pollution in Andong salt marsh, Hangzhou Bay, China

Microplastics are widely dispersed in the coastal and marine environment, and sediments are considered to be sinks for microplastics. In this study, a total of 53 sediment samples were removed from different depths of two sediment cores collected in Andong salt marsh, Hangzhou Bay. The microplastics were extracted from the sediment cores through a density floating separation method. The shape, size, and color of the microplastics was then observed under a microscope. Polymer types were identified using micro-Fourier transform infrared spectroscopy. The average abundance of microplastics was 13.2 ± 6.0 items 50 g−1 dry weight. The main components of microplastics were polystyrene, cellophane, polyethylene and polypropylene. The quantities of microplastics at different depths in the sediment cores were consistent with the history of microplastic pollution.

Rapid Loss of CO2 From the South Pacific Ocean During the Last Glacial Termination

AbstractDuring the termination of the last ice age, atmospheric CO2 rose ~80 ppm, but the origin of this carbon has not been fully resolved. Here we present novel constraints on the patterns and processes of deglacial CO2 release using three marine sediment cores from the southwest Pacific. Carbon isotopes (δ13C) and boron to calcium ratios (B/Ca) of benthic foraminiferal calcite provide records of the δ13C of total dissolved inorganic carbon (DIC) and carbonate ion concentrations ([CO32−]) in seawater, respectively. Together these properties indicate enhanced storage of respired CO2 between 1.2‐ and 2.5‐km water depth during the Last Glacial Maximum (19–23 thousand years ago, ka). The first major rise in atmospheric CO2 during the last deglaciation, at the time of Heinrich Stadial 1, was accompanied by increases in δ13C and [CO32−] at all core depths. The initial increases could be attributed to southward shifted westerly winds driving increased upwelling in the Southern Ocean, sending a signal of enhanced ventilation northward into the Pacific. Our results confirm that southern Pacific interior water masses served as an important reservoir for CO2 during the last glacial period, likely extracted from the atmosphere via the biologic pump. Some abrupt changes in Pacific carbon storage coincide with changes in Southern Ocean pH (Rae et al., 2018, https://doi.org/10.1038/s41586‐018‐0614‐0), upwelling indicators (Anderson et al., 2009, https://doi.org/10.1126/science.1167441), and pCO2 (Monnin et al., 2001, https://doi.org/10.1126/science.291.5501.112), indicating that portions of the deep Pacific carbon pool can be ventilated rapidly to the atmosphere via the Southern Ocean.

Digital Drill Core Models: Structure-from-Motion as a Tool for the Characterisation, Orientation, and Digital Archiving of Drill Core Samples

Structure-from-motion (SfM) photogrammetry enables the cost-effective digital characterisation of seismic- to sub-decimetre-scale geoscientific samples. The technique is commonly used for the characterisation of outcrops, fracture mapping, and increasingly so for the quantification of deformation during geotechnical stress tests. We here apply SfM photogrammetry using off-the-shelf components and software, to generate 25 digital drill core models of drill cores. The selected samples originate from the Longyearbyen CO2 Lab project’s borehole DH4, covering the lowermost cap rock and uppermost reservoir sequences proposed for CO2 sequestration onshore Svalbard. We have come up with a procedure that enables the determination of bulk volumes and densities with precisions and accuracies similar to those of such conventional methods as the immersion in fluid method. We use 3D printed replicas to qualitatively assure the volumes, and show that, with a mean deviation (based on eight samples) of 0.059% compared to proven geotechnical methods, the photogrammetric output is found to be equivalent. We furthermore splice together broken and fragmented core pieces to reconstruct larger core intervals. We unwrap these to generate and characterise 2D orthographic projections of the core edge using analytical workflows developed for the structure-sedimentological characterisation of virtual outcrop models. Drill core orthoprojections can be treated as directly correlatable to optical borehole-wall imagery data, enabling a direct and cost-effective elucidation of in situ drill core orientation and depth, as long as any form of borehole imagery is available. Digital drill core models are thus complementary to existing physical and photographic sample archives, and we foresee that the presented workflow can be adopted for the digitisation and digital storage of other types of geological samples, including degradable and dangerous ice and sediment cores and samples.

Organic-walled dinoflagellate cyst biostratigraphy of the upper Eocene to lower Oligocene Yazoo Formation, US Gulf Coast

Abstract. New data from a continuously cored succession, the Mossy Grove core, near Jackson, central Mississippi, recovered ∼137 m of marine clays (Yazoo Formation), spanning ∼5 Ma and including the critical Eocene–Oligocene transition (EOT) event. These clay-rich sediments yield well-preserved calcareous microfossil and palynomorph assemblages. Here, we present a new organic-walled dinoflagellate cyst (dinocyst) biostratigraphic framework, including the recognition of 23 dinocyst bioevents. These are integrated with new age constraints based on calcareous nannofossil biostratigraphy and a reassessment of the existing radiometric dates and planktonic foraminiferal biostratigraphy, permitting the establishment of a robust and significantly refined age model for the core. According to this new age model, a major increase in sedimentation rate – from ∼2.1 to ∼4.7 cm kyr−1 – is observed at a core depth of ∼89.1 m (∼34.4 Ma). In the new age model the section is significantly older than previously thought, by up to 1 Ma, with the Eocene-Oligocene boundary (∼33.89 Ma) placed ∼34 m below the level previously identified. With these more accurate age estimates, future isotopic and palaeoecological work on this core can be more precisely integrated with other, globally distributed records of the EOT.

Association of Horizontal Silo Pad Type, Elevation and Core Depth With Indicators of Silo Ramp Hygiene, Forage Quality, and Digestibility

Association of Horizontal Silo Pad Type, Elevation and Core Depth With Indicators of Silo Ramp Hygiene, Forage Quality, and Digestibility

Potential and limits of benthic foraminiferal ecological indices in paleoenvironmental reconstructions: a case from a Holocene succession of the Po Delta, Italy

Classical (paleo-)ecological indices extracted from benthic foraminiferal assemblages are commonly applied to determine past environmental conditions.We tested the efficiency of selected indices (including wall type proportion, epifaunal/infaunal ratio and pooled diversity indices) on benthic foraminifera from a Holocene shallow marine succession of the Po Delta, in order to evaluate their advantages, limits and differences. The paleoenvironmental record was determined integrating species composition of assemblages. All indices clearly discriminated between low and high riverine influence, even though the boundary at three different core depths revealed their different sensitivity to the faunal response under hanging environmental conditions in terms of organic matter and sediment supply. Specifically, the lowest boundary was highlighted by wall structural types and epifaunal/infaunal ratio that were able to track the first inputs of organic matter provided by the prograding Po River mouths. Upward, low sand concentration and moderate foraminiferal abundance (expressed as Total Foraminiferal Number) indicated significant supplies of fine-grained sediments within a prodelta paleoenvironment. Lastly, diversity indices revealed stressful prodelta conditions with remarkable low diversity and high dominance values. We show that high paleoenvironmental resolution can be obtained through the integration of faunal indices, species composition and sediment grain size within deltaic successions, where many indices should be considered to comprehensively understand the onset of riverine influenced conditions.

Internal structure of rock glaciers in Altai (The case of talus rock glacier in Dzhelo River Valley)

In 2019, a comprehensive study of the internal structure of the talus rock glacier in the Dzhelo River valley was carried out (North-Chuya Range). The identification of the internal structure was performed using electrical resistivity tomography and GPR sounding. In order to compare the internal structure of the rock glacier with its surface morphology, we carried out aerial photography and constructed a digital terrain model. The study revealed that the depth of the rock-ice core varies from 2.5-3 m to 10 m, and the thickness ranges from 7 m to 30 m. The consolidation cores of the rock-ice material are confined to inter-ridge depressions in the rock glacier body. The potential volume of a rock-ice core is 800 thousand m3, which is 53% of the rock glacier total volume, the ice volume in the rock-ice core can be as much as 400 thousand m3.

Small-scale heterogeneity of trace metals including rare earth elements and yttrium in deep-sea sediments and porewaters of the Peru Basin, southeastern equatorial Pacific

Abstract. Due to its remoteness, the deep-sea floor remains an understudied ecosystem of our planet. The patchiness of existing data sets makes it difficult to draw conclusions about processes that apply to a wider area. In our study we show how different settings and processes determine sediment heterogeneity on small spatial scales. We sampled solid phase and porewater from the upper 10 m of an approximately 7.4×13 km2 area in the Peru Basin, in the southeastern equatorial Pacific Ocean, at 4100 m water depth. Samples were analyzed for trace metals, including rare earth elements and yttrium (REY), as well as for particulate organic carbon (POC), CaCO3, and nitrate. The analyses revealed the surprisingly high spatial small-scale heterogeneity of the deep-sea sediment composition. While some cores have the typical green layer from Fe(II) in the clay minerals, this layer is missing in other cores, i.e., showing a tan color associated with more Fe(III) in the clay minerals. This is due to varying organic carbon contents: nitrate is depleted at 2–3 m depth in cores with higher total organic carbon contents but is present throughout cores with lower POC contents, thus inhibiting the Fe(III)-to-Fe(II) reduction pathway in organic matter degradation. REY show shale-normalized (SN) patterns similar to seawater, with a relative enrichment of heavy REY over light REY, positive LaSN anomaly, negative CeSN anomaly, and positive YSN anomaly and correlate with the Fe-rich clay layer and, in some cores, also correlate with P. We therefore propose that Fe-rich clay minerals, such as nontronite, as well as phosphates, are the REY-controlling phases in these sediments. Variability is also seen in dissolved Mn and Co concentrations between sites and within cores, which might be due to dissolving nodules in the suboxic sediment, as well as in concentration peaks of U, Mo, As, V, and Cu in two cores, which might be related to deposition of different material at lower-lying areas or precipitation due to shifting redox boundaries.

Trace metals in core sediments from a deep lake in eastern Turkey: Vertical concentration profiles, eco-environmental risks and possible sources.

The contents of 12 trace metals (Hg, As, Pb, Cd, Ni, Cr, Zn, Cu, Co, Mn, Al and Fe) in two sediment cores (Hz11-P02 and Hz11-P09) from the Lake Hazar, one of the deepest natural lakes in Turkey, were examined to evaluate vertical concentration profiles, possible sources, pollution status and eco-environmental risks of these metals. The highest concentrations of Cd and As were detected in the upper part (0-10cm depths) of core Hz11-P02, while Hg concentration was at a maximum in the upper part of core Hz11-P09. The concentrations of other metals except Cr were the highest in the bottom layer (depths below 100cm) of both cores. Among trace metals (TMs), Cr, Ni, Al and Mn in core Hz11-P02 and Mn in core Hz11-P09 showed statistically significant correlations with core depth (p<0.01). The mean concentrations of Hg, Pb, Cd, Cu, Zn, Co, Mn, Al and Fe in core Hz11-P02 were significantly higher than those in core Hz11-P09 (p<0.01). Also, the mean enrichment factor, geoaccumulation index and contamination factor values of As, Cu, Cd, Zn, Pb and Hg were higher in core Hz11-P02. The ecological risk index (RI) values for core Hz11-P02 were between 150 and 300 in 40.3% of the samples, indicating "moderate ecological risk", whereas the RI values for core Hz11-P09 were <150 in 100% of the samples, indicating "low ecological risk". Factor, cluster and correlation analyses, and contamination indices indicated that As and Hg in core Hz11-P02 predominantly originated from anthropogenic sources, while 12 trace metals in core Hz11-P09 derived from natural sources.

The radiolarian fauna during the Younger Dryas–Holocene transition in Andfjorden, northern Norway

We report on the changing radiolarian faunas from the Younger Dryas (ca.12.9 calibrated thousands of years BP [cal. Ky BP]) and into the Holocene (ca. 10.3 cal. Ky BP) in the core JM99-1200 from Andfjorden, northern Norway. Temperature reconstructions using both the Q-mode factor analysis and modern analogue technique methods show stable, cold temperatures below ca. 410 cm core depth, followed by abrupt warming into a relatively stable Holocene temperature regime. Age-depth modelling with three different methods gives an age of ca. 11.9–12.0 cal. Ky BP at this core depth, clearly older than the Younger Dryas–Holocene transition at ca. 11.65 cal. Ky BP according to ice core chronology. Considering that the age models may be insufficiently informed in an interval without radiometric dates, it is possible that the base of the Holocene is indeed at 410 cm, as indicated by the radiolarian and other core data. Such a change in the chronology would have implications for previously published work on the JM99-1200 core. Alternatively, the abrupt warming in Andfjorden predated the Younger Dryas–Holocene transition by a few hundred years. A distinct cold pulse at ca. 315–335 cm, or 11.4–11.5 cal. Ky BP is interpreted as the Preboreal Oscillation. The Preboreal Oscillation has not previously been detected in temperature curves based on planktic foraminifera in the same core, indicating that Radiolaria may be a more sensitive temperature indicator in this region.

Seasonal variations of biochemical and optical properties, physical dynamics and N stable isotopic composition in three northeastern Mediterranean basins (Aegean, Cretan and Ionian Seas)

Multidisciplinary surveys were conducted in October 2014, May 2015 and December 2015 in three major deep basins of the Eastern Mediterranean Sea (EMED) - the north Aegean Sea, the south Aegean (Cretan Sea) and its straits, and the south Ionian Sea - providing the most recent information on physical, biochemical and particle dynamics, along with nitrogen stable isotope composition. A north-south gradient in oligotrophy was observed, presumably related to more pronounced nutrient supply through the inflow of Black Sea Water and riverine inputs in the surface waters of the north Aegean Sea, coinciding with the relatively higher productivity in this area. Consumption rates of Dissolved Oxygen (DO) in the deep waters of the north Aegean Sea reveal the physical dynamics of the subsurface layers. According to this, it seems that no deep water formation has occurred in the Athos basin after 2008. In the Cretan Sea, the Transitional Mediterranean Water mass was identified at the layer 700-1200 m showing a slight decrease in its core depth, when compared with previous studies in the area. Seasonal variations of DO and salinity in the deep waters of the Ionian Sea indicate the intrusion of more oxygenated and less saline waters of Adriatic origin in the bathypelagic layer of the south Ionian Sea. Detailed determination of stable isotope ratios for nitrate (δ15N-NO3) and suspended particulate nitrogen (δ15N-PN) in various water column depth of the three basins showed a further decrease of the overall low EMED δ15N signal, when compared with previous studies in the area. This trend can be attributed to the onward atmospheric deposition of anthropogenic N to the EMED. The δ15N-PN depth profiles exhibited clear Rayleigh-type isotope fractionation and associated with remineralisation throughout the water column, implying that the unique, isolated oceanic basins of the Eastern Mediterranean serve as important marine observatories of anthropogenic influences on marine nutrient budgets.