- Woods Hole Oceanographic Institution
Clark 120A, MS #23
Woods Hole, MA
02543, USA - (+1) 508 289 3418
Historical industrial activities at the Horn Richterwil, on the shore of Lake Zurich (Switzerland), caused widespread metal contamination on land and in the adjacent lake sediments. This study provides an estimation of the age and source... more
Historical industrial activities at the Horn Richterwil, on the shore of Lake Zurich (Switzerland), caused widespread metal contamination on land and in the adjacent lake sediments. This study provides an estimation of the age and source of the contamination by using XRF core scanning, ICP-OES, and Hg-AFS for quantitative measurements of trace metals and MC-ICP-MS for the stable isotope analysis of mercury. Radiometric dating ($$^{137}$$ 137 Cs, $$^{210}$$ 210 Pb, and Pu dating) of two proximal cores and varve chronology in a distal core suggest two different contaminations, one stemming from around 1960 (Zn, Cd) and an earlier one from 1880 (Cr, Cu, Hg, Pb, Sn). The XRF data suggest two different contamination pathways: one by landfill of contaminated soil and another one by industrial wastewater effluents. Maximum concentrations found within all samples are in the range of per mil (dry weight) for Cr, Cu, Hg, Pb, Sn, and Zn and lie within the top 10 cm of the sediment cores. The a...
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Here, we present new results from seismic, geological, and geochemical studies conducted in 2015–2019 in the Petrozavodsk Bay of Lake Onego, NW Russia. The aims of these investigations were to (i) to characterize the structure of... more
Here, we present new results from seismic, geological, and geochemical studies conducted in 2015–2019 in the Petrozavodsk Bay of Lake Onego, NW Russia. The aims of these investigations were to (i) to characterize the structure of Quaternary deposits and (ii) provide new evidence of modern geodynamic movements and gas-seepage in Holocene sediments. The structure of the recovered deposits was composed of lacustrine mud, silt and sands from the Holocene, limno-glacial clays (varved clays) from the Late Glacial–Interglacial Transition, and glacial deposits (till) from the Late Pleistocene. The thickness of these deposits varied in different parts of the bay. Many pockmarks created by gases escaping and reaching sediment-water interface were observed in these deposits. Such pockmarks can play a significant role in the geochemical and biological processes in the bottom sediment surface, and gases that escape might modify the physicochemical characteristics of the environment.
Research Interests: Geology, Geochemistry, Minerals, Pleistocene, Quaternary, and 6 moreHolocene, Sediment, Interglacial, Bay, Varve, and Silt
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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or... more
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
CAPTAGE D’EAU DU LAC DE BIENNE – QUEL EST L’EMPLACEMENT IDEAL? L’actuelle station de conditionnement de l’eau du lac situee a Ipsach et ses points de captage definis en 1974 sont devenus obsoletes, et l’Energie Service Bienne prevoit de... more
CAPTAGE D’EAU DU LAC DE BIENNE – QUEL EST L’EMPLACEMENT IDEAL? L’actuelle station de conditionnement de l’eau du lac situee a Ipsach et ses points de captage definis en 1974 sont devenus obsoletes, et l’Energie Service Bienne prevoit de remplacer les installations du lac de Bienne. La repartition des courants et de la turbidite risquant de se modifier en raison des changements climatiques et de la mise hors service de la centrale nucleaire de Muhleberg, la question se pose de savoir si l’emplacement actuel du captage d’eau du lac de Bienne reste l’emplacement ideal. Selon cette etude de terrain realisee sur deux ans, l’emplacement actuel est favorable a differents titres. La temperature et l’oxygene ainsi que la turbidite generee par les affluents Aar et Suze jouent un role important dans la qualite de l’eau captee. Les conditions ideales de captage se trouvent dans une couche comprise entre 40 et 50 m de profondeur. De plus, dans le lac de Bienne, la stabilite des depots sediment...
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Significant uncertainties persist in the reconstruction of past sea surface temperatures in the eastern equatorial Pacific, especially regarding the amplitude of the glacial cooling and the details of the post-glacial warming. Here we... more
Significant uncertainties persist in the reconstruction of past sea surface temperatures in the eastern equatorial Pacific, especially regarding the amplitude of the glacial cooling and the details of the post-glacial warming. Here we present the first regional calibration of alkenone unsaturation in surface sediments versus mean annual sea surface temperatures (maSST). Based on 81 new and 48 previously published data points, it is shown that open ocean samples conform to established global regressions of Uk'37 versus maSST and that there is no systematic bias from seasonality in the production or export of alkenones, or from surface ocean nutrient concentrations or salinity. The flattening of the regression at the highest maSSTs is found to be statistically insignificant. For the near-coastal Peru upwelling zone between 11-15°S and 76-79°W, however, we corroborate earlier observations that Uk'37 SST estimates significantly over-estimate maSSTs at many sites. We posit that this is caused either by uncertainties in the determination of maSSTs in this highly dynamic environment, or by biasing of the alkenone paleothermometer toward El Niño events as postulated by Rein et al. (2005).
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High-resolution proxy-based paleoenvironmental records derived from peatlands provide important insights into climate changes over centennial to millennial timescales. In this study, we present a composite climatic index (CCI) for the... more
High-resolution proxy-based paleoenvironmental records derived from peatlands provide important insights into climate changes over centennial to millennial timescales. In this study, we present a composite climatic index (CCI) for the Hani peatland from northeastern China, based on an innovative combination of pollen-spore, phytolith, and grain size data. We use the CCI to reconstruct variations of the East Asian summer monsoon (EASM) intensity during the Holocene. This is accomplished with complete ensemble empirical mode decomposition (CEEMD), REDFIT, and cross-wavelet coherency analysis to reveal the periodicities (frequencies) of the multi-proxy derived CCI sequences and to assess potential external forcing of the EASM. The results showed that periodicities of ca. 300–350, 475, 600, 1075, and 1875 years were present in the Hani CCI sequence. Those periodicities are consistent with previously published periodicities in East Asia, indicating they are a product of external climate ...
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Autochthonous calcite precipitation is an important process for C-fixation in hard-water lakes, which is mainly induced by the photosynthesis of planktonic microorganisms. Among these, the widespread calcifying green alga Phacotus... more
Autochthonous calcite precipitation is an important process for C-fixation in hard-water lakes, which is mainly induced by the photosynthesis of planktonic microorganisms. Among these, the widespread calcifying green alga Phacotus lenticularis (Ehrenberg) Diesing contributes to biogenic calcite precipitation in temperate regions. Its role in carbonate precipitation needs to be investigated, because there are no studies dedicated to the quantitative contribution of Phacotus shells to long term carbonate sequestration in hard-water lake sediments. In order to fill this gap, the Phacotus shell content in the sediments of four German hard-water lakes was determined and compared to the fraction of Phacotus shells in the total suspended autochthonous calcite of the euphotic zone.It was found that the Phacotus shells contributed at least 10% to the autochthonous carbonate precipitation in the upper water column in three investigated lakes. During a Phacotus mass occurrence with a cell dens...
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The hydrogen isotope composition (δ<sup>2</sup>H) of biomarkers produced by algae is strongly influenced by the δ<sup>2</sup>H values of the water in which they grew. δ<sup>2</sup>H values of algal... more
The hydrogen isotope composition (δ<sup>2</sup>H) of biomarkers produced by algae is strongly influenced by the δ<sup>2</sup>H values of the water in which they grew. δ<sup>2</sup>H values of algal biomarkers preserved in lake sediments are thus a useful tool for reconstructing past changes in lake water δ2H values, which can be used to infer hydroclimate variability. However, studies from laboratory cultures of marine algae have shown that a number of factors can influence the magnitude of hydrogen isotope fractionation between algal lipids and their source water, including temperature and growth rates. Quantifying the natural extent of these changes in freshwater lacustrine settings and identifying their causes is essential for robust application of δ<sup>2</sup>H values of algal lipids as paleohydroclimate proxies, yet the influence of these factors remains poorly constrained.<br><br> This work targets the effect of temp...
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Research Interests: Geochemistry, Prediction, Productivity, Sea Ice, Concentration, and 15 moreGrowth, Atmospheric sciences, Atmosphere, Global, Exportation, Last Glacial Maximum, Nutrients, Physiological Response, Marine Isotope Stage, Leakage, Deep water, Deglaciation, Global Biogeochemical Cycles, Ratio, and Glacial periods
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Research Interests: Geology and Geochemistry
The Joux Valley (Swiss Jura Mountains) has a rather unusual history of human occupation, characterized by tardive but extensive settlement since the Late Middle Ages, followed by an intensive period of industrial development. To estimate... more
The Joux Valley (Swiss Jura Mountains) has a rather unusual history of human occupation, characterized by tardive but extensive settlement since the Late Middle Ages, followed by an intensive period of industrial development. To estimate the links between human activities and environmental consequences, sediment cores were retrieved in Lake Joux and submitted to a multiproxy analysis (high-resolution photographs, magnetic susceptibility, density, x-ray fluorescence, grain size, organic geochemistry, 14C, 210Pb and 137Cs dating). The diversity of anthropication phases, defined from historical data, is clearly recognized in the lake archive. The record suggests the region was mainly under climatic influence until the end of the 13th century. The growth of settlements in the valley and the associated massive deforestation is recorded by increasing terrestrial inputs, reflecting large-scale soil destabilization, which subsequently persists despite the transition from farming to industri...
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The western equatorial Pacific is a highly dynamic region, playing a significant role in both tropical and extra-tropical climates through its strong influence on the El Niño-Southern Oscillation (ENSO) phenomenon and the position of the... more
The western equatorial Pacific is a highly dynamic region, playing a significant role in both tropical and extra-tropical climates through its strong influence on the El Niño-Southern Oscillation (ENSO) phenomenon and the position of the Inter-tropical Convergence Zone (ITCZ). While the modern behaviours of these climate systems are reasonably well understood, past behaviours are subject to debate. N-alkanes (biomarkers that
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ABSTRACT Reconstruction of past ocean and climate conditions from marine sediments relies on proxies, measurable descriptors of past environmental conditions preserved in the sedimentary record. One such proxy is alkenone unsaturation,... more
ABSTRACT Reconstruction of past ocean and climate conditions from marine sediments relies on proxies, measurable descriptors of past environmental conditions preserved in the sedimentary record. One such proxy is alkenone unsaturation, expressed as the UK37 index. Alkenones are synthesized mainly by a specific group of marine phytoplankton called coccolithophorids, and their degree of unsaturation has been established to be intimately linked with mean annual sea surface temperatures (maSST) during coccolithophorid growth. However, recent studies have hinted at a seasonal bias of coccolithophorid growth and/or non-thermal effects, such as salinity or nutritional status, to also affect alkenone unsaturation, possibly explaining subtle deviations from the tight linear correlation between maSST and UK&#39;37. Here we present new results from culture studies and a compilation of UK&#39;37 in surface sediments from the eastern tropical Pacific (ETP). Cultures of marine Prymenesiophyceae Emiliania huxleyi (CCMP1742 and CCMP1516) and Gephyrocapsa oceanica (CCMP2054) were grown at 22°C at 3 different salinities (28, 32, 36 psu). E.hux (CCMP1742) was also cultured at 10°C and 16°C in these same salinities. The tetraunsaturated methyl alkenone (C37:4me) was observed only in the cultures grown at 10°C, and the results show that salinity has no significant effect on UK&#39;37 or on the relative abundance of C37:4 to the total abundance of C37 alkenones (37:4%). The UK&#39;37 in surface sediments from the ETP does largely follow established global calibrations of UK&#39;37 versus maSST, without obvious ``warm-end bias&#39;&#39;, but strong seasonality in coccolithophorid growth does appear to skew the sedimentary UK&#39;37 record toward warmer SSTs during the non-upwelling season. This latter effect, however, appears to be limited to a few sites in the upwelling region off Peru.
ABSTRACT The hydrologic response to climate forcing in the Indo-Pacific warm pool region has varied spatially over the past 25,000 years1, 2, 3, 4, 5. For example, drier conditions are inferred on Java and Borneo for the period following... more
ABSTRACT The hydrologic response to climate forcing in the Indo-Pacific warm pool region has varied spatially over the past 25,000 years1, 2, 3, 4, 5. For example, drier conditions are inferred on Java and Borneo for the period following the end of the Last Glacial Maximum, whereas wetter conditions are reconstructed for northwest Australia4. The response of vegetation to these past rainfall variations is poorly constrained. Using a suite of 30 surface marine sediment samples from throughout the Indo-Pacific warm pool, we demonstrate that today the stable isotopic composition of vascular plant fatty acids (δ13Cfa) reflects the regional vegetation composition. This in turn is controlled by the seasonality of rainfall consistent with dry season water stress6. Applying this proxy in a sediment core from offshore northeast Borneo, we show broadly similar vegetation cover during the Last Glacial Maximum and the Holocene, suggesting that, despite generally drier glacial conditions1, 7, there was no pronounced dry season. In contrast, δ13Cfa and pollen data from a core off the coast of Sumba indicate an expansion of C4 herbs during the most recent glaciation, implying enhanced aridity and water stress during the dry season. Holocene vegetation trends are also consistent with a response to dry season water stress. We therefore conclude that vegetation in tropical monsoon regions is susceptible to increases in water stress arising from an enhanced seasonality of rainfall, as has occurred8 in past decades.
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ABSTRACT Paleoceanography aims to unravel information on the state of the oceans from the pelagic sediments deposited on the ocean floor, but the record is complicated. Pelagic sediments are popularly perceived to accumulate by particles... more
ABSTRACT Paleoceanography aims to unravel information on the state of the oceans from the pelagic sediments deposited on the ocean floor, but the record is complicated. Pelagic sediments are popularly perceived to accumulate by particles falling vertically to deposit simply draping their underlying basin topography and that their properties reflect their overlying water columns. However, our work on the equatorial Pacific region with seismic data and that of others with radiogenic isotopes such as Th230 suggests that their accumulation can be far less regular. At an abyssal hill scale, sediments drape or preferentially fill basins, as might be expected from gravity-driven transport. At a larger 50-100 km scale, their accumulation also varies significantly, suggesting varied affects of carbonate dissolution and particle transport by currents, processes that could strongly affect paleoceanographic information inferred from cores. The origin of this variability lies in how both the physical and chemical state of the ocean has changed throughout the Neogene but is very poorly understood. In this project, we aim to tackle the issue of how pelagic sediments accumulate, using seismic reflection data combined with ground truth from scientific drilling, in particular, from recent expeditions 320 and 321 of the Integrated Ocean Drilling Program. The main dataset to be studied comprises new high-resolution seismic reflection data collected on R/V Roger Revelle in 2006, jointly funded by the UK&#39;s NERC and the USA&#39;s NSF. Those data, along with seismic data collected during previous expeditions of R/V Washington, now provides information on pelagic deposits across a region of the central Pacific more than 3000 km across, allowing variability potentially to be analysed across a vast range of scales.
Lake sediments constitute natural archives of past environmental changes. Historically, research has focused mainly on generating regional climate records, but records of human impacts caused by land use and exploitation of freshwater... more
Lake sediments constitute natural archives of past environmental changes. Historically, research has focused mainly on generating regional climate records, but records of human impacts caused by land use and exploitation of freshwater resources are now attracting scientific and management interests. Long-term environmental records are useful to establish ecosystem reference conditions, enabling comparisons with current environments and potentially allowing future trajectories to be more tightly constrained. Here we review the timing and onset of human disturbance in and around inland water ecosystems as revealed through sedimentary archives from around the world. Palaeolimnology provides access to a wealth of information reflecting early human activities and their corresponding aquatic ecological shifts. First human impacts on aquatic systems and their watersheds are highly variable in time and space. Landscape disturbance often constitutes the first anthropogenic signal in palaeoli...
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Six sediment cores from a transect spanning 11? of latitude across the equator in the EEP were examined in an effort to reconstruct changes in sea surface temperatures, nutrient supply and utilization, primary productivity, and... more
Six sediment cores from a transect spanning 11? of latitude across the equator in the EEP were examined in an effort to reconstruct changes in sea surface temperatures, nutrient supply and utilization, primary productivity, and denitrification rates in the adjacent oxygen minimum ...