147 research outputs found

    Rapid Climate Changes in the Westernmost Mediterranean (Alboran Sea) Over the Last 35 kyr: New Insights From Four Lipid Paleothermometers (UK' 37, TEXH 86, RI-OH', and LDI)

    Get PDF
    This study was supported by Grant PID2019-104624RB-I00 funded by MCIN/AEI/ 10.13039/501100011033, Grants FEDER/Junta de Andalucia-Consejeria de Economia y Conocimiento P18-RT-3804 and P18-RT- 4074, and Research Group RNM-179 (Junta de Andalucia). The authors also thank the Unidad Cientifica de Excelencia UCE-PP2016-05 (University of Granada). This study also received funding from the Netherlands Earth System Science Center (NESSC) through a gravitation grant (024.002.001) to J. S. Sinninghe Damste and S. Schouten from the Dutch Ministry for Education, Culture and Science. M. Rodrigo-Gamiz acknowledges funding from the Andalucia Talent Hub Program co-funded by the European Union's Seventh Framework Program (COFUND-Grant Agreement No 291780) and the Junta de Andalucia and from the Juan de la Cierva-Incorporacion program in the University of Granada (IJCI-2017-33,755) from Secretaria de Estado de I + D + i, Spain. We thank the captain, crew, and participants of the Gasalb cruise onboard R/V Pelagia for assistance during sampling. We are also grateful to the Poznan Radiocarbon Laboratory (Poland), the Leibniz Laboratory for Radiometric Dating and Stable Isotope Research (Germany), and the Centre for Scientific Instrumentation (CIC, Spain) for analyses. The authors thank Jort Ossebaar, Anchelique Mets, Marianne Baas and Karsten Dekker (all at NIOZ) for laboratory assistance. Thanks to Prof. Giuseppe Siani (Universite Paris-Sud Orsay) and Jose Manuel Mesa Fernandez for their help and comments on the age model. We thank the Associate Editor, Dr. Yige Zhang, two anonymous reviewers, and Dr. Felix J. Elling for their helpful comments that improved the manuscript substantially. Funding for open access charge from Universidad de Granada/CBUA.The westernmost Mediterranean is one of the most sensitive areas to global climate change and high sedimentation rates allow recording high frequency variability. We present a high-resolution paleotemperature reconstruction over the last 35 kyr using, for the first time, four independent organic sea surface temperature (SST) proxies (UK' 37, TEXH 86, RI-OH' and LDI) based on alkenones, (hydroxy) isoprenoid GDGTs, and long-chain diols. We also generated a δ18O of planktonic foraminifera G. bulloides record together with records of bulk parameters (total organic carbon content, δ13Corg) and the accumulation rates of different biomarkers to provide insights into terrestrial input and primary producers. All derived-SST records showed similar trends over the last 35 kyr, revealing abrupt temperature variations during the last seven Dansgaard- Oeschger (D/O) cycles, the three Heinrich (H) events, the Last Glacial Maximum, and the Younger Dryas. H3 is recognized as the coldest event, while H1 was recorded by all SST proxies as the most abrupt one. In general, TEXH 86-, RI-OH'- and LDI-SST estimates were lower than those obtained from UK' 37. The LDI paleothermometer recorded the largest range of absolute SSTs over the whole period (ca. 20°C) followed by RI-OH' (ca. 16°C). TEXH 86, RI-OH' and LDI proxies reflected sudden SST changes during the D/O 6 and 5 particularly well. Low BIT values and the abundance of C32 1,15-diol in range with typical marine values indicated only minor input of continental organic matter. Accumulation rates of different lipid biomarkers were generally modulated by D/O cycles, suggesting enhanced productivity during D/O interstadials and the Bölling- Alleröd period.Grants FEDER/Junta de Andalucia-Consejeria de Economia y Conocimiento PID2019-104624RB-I00 MCIN/AEI/ 10.13039/501100011033 P18-RT-3804 P18-RT- 4074Research Group RNM-179Unidad Cientifica de Excelencia UCE-PP2016-05Netherlands Earth System Science Center (NESSC) through a gravitation grant 024.002.001Andalucia Talent Hub Program - European Union's Seventh Framework Program (COFUND-Grant) 291780 Junta de AndaluciaJuan de la Cierva-Incorporacion program in the University of Granada from Secretaria de Estado de I + D + i, Spain IJCI-2017-33,755Universidad de Granada/CBU

    Constraints on the applicability of the organic temperature proxies UK'37, TEX86 and LDI in the subpolar region around Iceland

    Get PDF
    The Supplement related to this article is available online at doi:10.5194/bg-12-6573-2015-supplement.Subpolar regions are key areas for studying natural climate variability due to their high sensitivity to rapid environmental changes, particularly through sea surface temperature (SST) variations. Here, we have tested three independent organic temperature proxies (UK'37; TEX86; and the long-chain diol index, LDI) regarding their potential applicability for SST reconstruction in the subpolar region around Iceland. UK'37, TEX86 and TEXL86 temperature estimates from suspended particulate matter showed a substantial discrepancy with instrumental data, while long-chain alkyl diols were below the detection limit at most of the stations. In the northern Iceland Basin, sedimenting particles revealed a seasonality in lipid fluxes, i.e., high fluxes of alkenones and glycerol dialkyl glycerol tetraethers (GDGTs) were measured during late spring and during summer and high fluxes of long-chain alkyl diols during late summer. The flux-weighted average temperature estimates had a significant negative (ca. 2.3 °C for UK'37) and positive (up to 5 °C for TEX86) offset with satellite-derived SSTs and temperature estimates derived from the underlying surface sediment. UK'37 temperature estimates from surface sediments around Iceland correlate well with summer mean sea surface temperatures, while TEX86-derived temperatures correspond with both annual and winter mean 0–200 m temperatures, suggesting a subsurface temperature signal. Anomalous LDI-SST values in surface sediments and low mass flux of 1,13- and 1,15-diols compared to 1,14-diols suggest that Proboscia diatoms are the major sources of long-chain alkyl diols in this area rather than eustigmatophyte algae, and therefore the LDI cannot be applied in this region.This work was supported by the Earth and Life Sciences Division of the Netherlands Organization for Scientific Research (NWO-ALW) by a grant (ALW 820.01.013) to J. S. Sinninghe Damsté. The research leading to these results has received funding from the European Research Council (ERC) under the European Union’s Seventh Framework Program (FP7/2007-2013) ERC grant agreement 226600

    A solution for robotized sampling in wastewater plants

    Get PDF
    © 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This work presents a solution to automatize the water sampling process of outdoor basins in a wastewater treatment plant. The system proposed is based on the utilization of collaborative robotics: a team of an UAV and a terrestrial robotic platform make a route along the plant collecting and storing the water samples. The architecture of the designed system is described in terms of functional blocks, and implementation details including software frameworks and hardware on the UAV are provided. As the objective of the system is industry levels of robustness and performance, the UAV use is minimized and subjected to control from the robotic ground platform, reducing risks associated with autonomous UAV. To conclude, results from experiments performed to validate the viability of the system and study several design decisions are presented and briefly discussed, including: estimation of the accuracy of several GNSS technologies on the plant, viability of the landing operation over a mobile robotic platform and controlling a quadrotor over waters.Peer ReviewedPostprint (author's final draft

    Algal lipids reveal unprecedented warming rates in alpine areas of SW Europe during the industrial period

    Get PDF
    Alpine ecosystems of the southern Iberian Peninsula are among the most vulnerable and the first to respond to modern climate change in southwestern Europe. While major environmental shifts have occurred over the last ~ 1500 years in these alpine ecosystems, only changes in the recent centuries have led to abrupt environmental responses, but factors imposing the strongest stress have been unclear until now. To understand these environmental responses, this study, for the first time, has calibrated an algal lipid-derived temperature proxy (based on long-chain alkyl diols) to instrumental historical data extending alpine temperature reconstructions to 1500 years before present. These novel results highlight the enhanced effect of greenhouse gases on alpine temperatures during the last ~ 200 years and the longterm modulating role of solar forcing. This study also shows that the warming rate during the 20th century (~ 0:18 ºC per decade) was double that of the last stages of the Little Ice Age (~ 0:09 ºC per decade), even exceeding temperature trends of the high-altitude Alps during the 20th century. As a consequence, temperature exceeded the preindustrial record in the 1950s, and it has been one of the major forcing processes of the recent enhanced change in these alpine ecosystems from southern Iberia since then. Nevertheless, other factors reducing the snow and ice albedo (e.g., atmospheric deposition) may have influenced local glacier loss, since almost steady climate conditions predominated from the middle 19th century to the first decades of the 20th century.This research has been supported by the Seventh Framework Programme (grant no. NAOSIPUK (623027)), the Ministerio de Economía y Competitividad, Secretaría de Estado de Investigación, Desarrollo e Innovación (grant no. CGL2017-85415- R), the Ministerio de Economía y Competitividad, Secretaría de Estado de Investigación, Desarrollo e Innovación (grant no. CGL2013- 47038-R), the Ministerio de Economía y Competitividad, Secretaría de Estado de Investigación, Desarrollo e Innovación (grant no. CGL2011-23483), and the Consejería de Economía, Innovación, Ciencia y Empleo, Junta de Andalucía, Agencia de Innovación y Desarrollo de Andalucía (grant no. P11-RNM 7332). This research has also been supported by grant no. 87/2007 of the Organismo Autónomo Parques Nacionales (OAPN)-Ministerio de Medio Ambiente, the research group no. RNM-190 of the Plan Andaluz de Investigación, Desarrollo e Innovación (Junta de Andalucía), and the Ramón y Cajal Fellowship (fellowship no. RYC-2015-18966) of the Ministerio de Economía y Competitividad, Secretaría de Estado de Investigación, Desarrollo e Innovación

    Sea surface temperature variations in the western Mediterranean Sea over the last 20 kyr: A dual-organic proxy (U<super>K'</super><sub>37</sub> and LDI) approach

    Get PDF
    A high-resolution sea surface temperature (SST) reconstruction of the western Mediterranean was accomplished using two independent, algae-based molecular organic proxies, i.e., the U-37(K) index based on long-chain unsaturated ketones and the novel long-chain diol index (LDI) based on the relative abundances of C-28 and C-30 1,13- and 1,15-diols. Two marine records, from the western and eastern Alboran Sea basin, spanning the last 14 and 20kyr, respectively, were studied. Results from the surface sediments suggest that the two proxies presently reflect seasons with similar SST or simply annual mean SST. Both proxy records reveal the transition from the Last Glacial Maximum to the Holocene in the eastern Alboran Sea with an SST increase of approximately 7 degrees C for U-37(K) and 9 degrees C for LDI. Minimum SSTs (10-12 degrees C) are reached at the end of the Last Glacial Maximum and during the last Heinrich event with a subsequent rapid SST increase in LDI-SST toward the beginning of the Bolling period (20 degrees C), while U-37(K)-SST remains constantly low (similar to 12 degrees C). The Bolling-Allerod period is characterized by a rapid increase and subsequent decrease in U-37(K)-SST, while the LDI-SST decrease continuously. Short-term fluctuations in U-37(K)-SST are probably related to the availability of nutrients and seasonal changes. The Younger Dryas is recorded as a short cold interval followed by progressively warmer temperatures. During the Holocene, the general lower U-37(K)-derived temperature values in the eastern Alboran (by approximately 1.5-2 degrees C) suggest a southeastward cold water migration by the western Alboran gyre and divergence in the haptophyte blooming season between both basins.<br>Key Points<br><list list-type="bulleted" id="palo20073-list-0001"> <list-item id="palo20073-li-0001">High-resolution SST reconstruction is performed in the westernmost Mediterranean <list-item id="palo20073-li-0002">Two algae-based proxies show the temperature evolution for the last 20 kyr <list-item id="palo20073-li-0003">Derived SSTs suggest different growth seasons of alkenone and diol producer

    Evaluation of long chain 1,14-alkyl diols in marine sediments as indicators for upwelling and temperature

    Get PDF
    Long chain alkyl diols form a group of lipids occurring widely in marine environments. Recent studies have suggested several palaeoclimatological applications for proxies based on their distributions, but have also revealed uncertainty about their applicability. Here we evaluate the use of long chain 1,14-alkyl diol indices for reconstruction of temperature and upwelling conditions by comparing index values, obtained from a comprehensive set of marine surface sediments, with environmental factors such as sea surface temperature (SST), salinity and nutrient concentration. Previous studies of cultures indicated a strong effect of temperature on the degree of saturation and the chain length distribution of long chain 1,14-alkyl diols in Proboscia spp., quantified as the diol saturation index (DSI) and diol chain length index (DCI), respectively. However, values of these indices for surface sediments showed no relationship with annual mean SST of the overlying water. It remains unknown as to what determines the DSI, although our data suggest that it may be affected by diagenesis, while the relationship between temperature and DCI may be different for different Proboscia species. In addition, contributions from algae other than Proboscia diatoms may affect both indices, although our data provide no direct evidence for additional long chain 1,14-alkyl diol sources. Two other indices using the abundance of 1,14-diols vs. 1,13-diols and C30 1,15-diols have been applied previously as indicators for upwelling intensity at different locations. The geographical distribution of their values supports the use of 1,14 diols vs. 1,13 diols [C28 + C30 1,14-diols]/[(C28 + C30 1,13-diols) + (C28 + C30 1,14-diols)] as a general indicator for high nutrient or upwelling conditions

    Recent Progress on Tau Lepton Physics

    Get PDF
    Some important aspects of hadronic tau decays are reviewed: the determination of alpha_s from the inclusive tau hadronic width, the measurement of |V_{us}| through the Cabibbo-suppressed decays of the tau, and the theoretical description of the tau -> nu_tau K pi spectrum. The present status of other relevant electroweak topics, such as charged-current universality tests or bounds on lepton-flavour violation, has been already summarized in a previous review.Comment: Proc. 14th International QCD Conference (QCD08), Montpellier, 7-12th July 200

    Tau Physics: Theory Overview

    Get PDF
    The present status of some selected topics on tau physics is presented: charged-current universality tests, bounds on lepton-flavour violation, the determination of alpha_s from the inclusive tau hadronic width, the measurement of |V_{us}| through the Cabibbo-suppressed decays of the tau, and the theoretical description of the "tau -> nu_tau K pi" spectrum.Comment: Invited talk at the 2008 International Workshop on e+e- collisions from Phi to Psi (PhiPsi08, Frascati, Italy, 7-10 April 2008

    Holocene summer temperature reconstruction based on a chironomid record from Sierra Nevada, southern Spain

    Get PDF
    This study was supported by projects CGL2013-47038-R, CGL2017-85415-R and PID2021-125619OB-C21/C22, funded by the Ministerio de Ciencia e Innovación of Spain, the Agencia Estatal de Investigación and the Fondo Europeo de Desarrollo Regional FEDER MCIN/AEI/10.13039/501100011033/FEDER, UE”; Junta de Andalucía I + D + i Junta de Andalucía 2020 Retos P-20-00059, UGR-FEDER B-RNM-144-UGR18, UGR-FEDER A-RNM-336-UGR20, Project cofinanced by FEDER and LifeWatch-Eric LifeWatch-2019-10-UGR-01 and the research group RNM-190 (Junta de Andalucía). RSA acknowledges several travel grants from Northern Arizona University to support this work. JC thanks the Ministerio de Ciencia e Innovación of Spain for the Juan de la Cierva Formación postdoctoral fellowship. ALA acknowledges the predoctoral fellowship BES-2018-084293 provided by the MCIN/AEI/10.13039/501100011033/. CLB acknowledges the European Union for her Marie Sklodowska-Curie grant agreement number 892487 under Horizon 2020 funds. LJ acknowledges the Ministry of Universities of Spain for her Margarita Salas grant (MS2021-204) financed by the European Union -Next Generation EU funds.Obtaining accurate temperature reconstructions from the past is crucial in understanding the consequences of changes in external climate forcings, such as orbital-scale insolation or multidecadal to centennial-scale variability on the climate system and the environment. In addition, these reconstructions help in comprehending the amplitude of natural temperature changes in the past, which can assist in evaluating the amplitude and rate of recent anthropogenic global warming. Here we present the first detailed Holocene mean July air temperature reconstruction based on chironomid assemblages from sediments retrieved from Laguna de Río Seco, an alpine lake in Sierra Nevada, southern Spain. Coldest climate conditions are recorded during the last glacial maximum and the last deglaciation. Warming occurred in the Early Holocene and warmest summer temperature conditions and the Holocene thermal maximum (HTM) occurred in the interval roughly between 9000 and 7200 cal yr BP, concurrent with summer insolation maxima. Rapid cooling of ∼1.5 °C occurred after the warmest maximum and between ∼7200 and 6500 cal yr BP, and temperatures stabilized between ∼6500 and 3000 cal yr BP. A further cooling began ∼3000 cal yr BP and culminated with coldest summer conditions during the Dark Ages (DA) and Little Ice Age (LIA) at ∼1550 cal yr BP (∼400 CE) and ∼200 cal yr BP (∼1750 CE), respectively. This cooling temperature trend was interrupted by warmer conditions during the Iberian-Roman Humid Period (IRHP) ∼2000 cal yr BP and during the Medieval Climate Anomaly (MCA) at ∼1000 cal yr BP. Our reconstruction shows a greater than two-degree cooling during the Middle and Late Holocene, agreeing with global mean surface temperature (GMST) reconstructions. Modern climate warming (MCW) during summer exceeds the two-degree Celsius forecasted for the future due to anthropogenic greenhouse gases, suggesting that recent warming is amplified at high elevations. Alpine environments and the biodiversity contained there are thus in danger if the observed temperature trend continues in the next decades.Ministerio de Ciencia e Innovación of Spain CGL2013-47038-R, CGL2017-85415-R, PID2021-125619OB-C21/C22Agencia Estatal de InvestigaciónFondo Europeo de Desarrollo Regional FEDER MCIN/AEI/10.13039/501100011033/FEDER, UEJunta de Andalucía P-20-00059, UGR-FEDER B-RNM-144-UGR18, UGR-FEDER A-RNM-336-UGR20FEDERLifeWatch-Eric LifeWatch-2019-10-UGR-01Research group RNM-190 (Junta de Andalucía)Northern Arizona UniversityMinisterio de Ciencia e Innovación of SpainMCIN/AEI/10.13039/501100011033/ BES-2018-084293Horizon 2020 European Union Marie Sklodowska-Curie 892487European Union -Next Generation EU funds MS2021-20

    Algal lipids reveal unprecedented warming rates in alpine areas of SW Europe during the industrial period

    Get PDF
    Alpine ecosystems of the southern Iberian Peninsula are among the most vulnerable and the first to respond to modern climate change in southwestern Europe. While major environmental shifts have occurred over the last similar to 1500 years in these alpine ecosystems, only changes in the recent centuries have led to abrupt environmental responses, but factors imposing the strongest stress have been unclear until now. To understand these environmental responses, this study, for the first time, has calibrated an algal lipid-derived temperature proxy (based on long-chain alkyl diols) to instrumental historical data extending alpine temperature reconstructions to 1500 years before present. These novel results highlight the enhanced effect of greenhouse gases on alpine temperatures during the last similar to 200 years and the long-term modulating role of solar forcing. This study also shows that the warming rate during the 20th century (similar to 0.18 degrees C per decade) was double that of the last stages of the Little Ice Age (similar to 0.09 degrees C per decade), even exceeding temperature trends of the high-altitude Alps during the 20th century. As a consequence, temperature exceeded the preindustrial record in the 1950s, and it has been one of the major forcing processes of the recent enhanced change in these alpine ecosystems from southern Iberia since then. Nevertheless, other factors reducing the snow and ice albedo (e.g., atmospheric deposition) may have influenced local glacier loss, since almost steady climate conditions predominated from the middle 19th century to the first decades of the 20th century.Peer reviewe
    corecore