bluuebunny/crossref_metadata_2025 huggingface dataset:
Raman Spectral Trends in ‘low-temperature’ Carbonaceous Materials.
Authors: Muirhead David
Published: March 2021

Amorphous carbonaceous materials are typically those that would be considered immature, at temperatures below 300°C, in a typical sedimentary basin burial setting. Only recently has there been much discussion on the efficacy of Raman spectroscopy on amorphous carbon at temperatures below 300°C. Here we present data from a variety of published sources alongside our own data reviewing the apparent trends in amorphous carbon with some discussion related to thermal regime (intensity, duration), with case studies including intruded host rocks, fold and thrust belts and wildfires. We conclude that Raman spectroscopy can be applied successfully to ‘low-temperature’ carbonaceous material whilst noting the challenges faced to fully understand the physio-chemical mechanisms at these temperature ranges.
ArcticDEM in Google Earth Engine: tools for rapid analysis of multi-temporal data covering glacial environments
Authors: Lea James , Shiggins Connor , Brough Stephen , Livingstone Stephen , McNabb Robert
Published: March 2021

ArcticDEM data products include timestamped high spatial resolution (2 and 10 m) digital elevations models (DEMs) covering the period 2009-2017, offering the potential for monitoring ice surface change, structural evolution, geomorphological and proglacial change. However, their varying quality, spatial and temporal data coverage, large file size and requirement for co-registration provide challenges to user accessibility and interrogation of these datasets. Inclusion of these data in the cloud computing based Google Earth Engine (GEE) platform provides opportunities for rapid analysis, though poses its own barriers to access for users through the necessity for familiarity with either JavaScript or Python coding environments. Here we present tools that allow ArcticDEM data to be rapidly queried by users with no coding background through an intuitive graphical user interface, with the aim of improving the accessibility of these datasets for the glacial and earth surface process communities.

 

The tools are intended to provide a means for users to perform basic data extraction from available DEMs of a given area. These include the extraction of elevation changes occurring along user defined transects, and simple DEM differencing of areas of interest. As part of data pre-processing in GEE, tiles are co-registered using dX, dY and dZ corrections provided within the ArcticDEM metadata, while areas of poor data quality are automatically detected and masked out. A full range of metadata associated with each DEM are also appended to outputs, that will allow users to undertake post-processing of results where needed. While provisional results indicate that the tools perform well, due to inaccuracies in co-registration metadata they are not yet suitable for applications where high levels of precision are required (e.g. snow depth) and in areas of very steep terrain (e.g. rock face changes). We hope to address these issues in the future, though it should be noted that such modifications are likely to significantly increase computation time.
Plasma Diagnostics of Microflares observed by STIX and AIA
Authors: Saqri Jonas , Veronig Astrid , Dickson Ewan , Krucker Säm , Battaglia Andrea Francesco , Battaglia Marina , Xiao Hualin , Warmuth Alexander , STIX Team the
Published: March 2021

Solar flares are generally thought to be the impulsive release of magnetic energy giving rise to a wide range of solar phenomena that influence the heliosphere and in some cases even conditions of earth. Part of this liberated energy is used for particle acceleration and to heat up the solar plasma. The Spectrometer/Telescope for Imaging X-rays (STIX) instrument onboard the Solar Orbiter mission launched on February 10th 2020 promises advances in the study of solar flares of various sizes. It is capable of measuring X-ray spectra from 4 to 150 keV with 1 keV resolution binned into 32 energy bins before downlinking. With this energy range and sensitivity, STIX is capable of sampling thermal plasma with temperatures of≳10 MK, and to diagnose the nonthermal bremsstrahlung emission of flare-accelerated electrons. During the spacecraft commissioning phase in the first half of the year 2020, STIX observed 68 microflares. Of this set, 26 events could clearly be identified in at least two energy channels, all of which originated in an active region that was also visible from earth. These events provided a great opportunity to combine the STIX observations with the multi-band EUV imagery from the Atmospheric Imaging Assembly (AIA) instrument on board the earth orbiting Solar Dynamics Observatory (SDO). For the microflares that could be identified in two STIX science energy bands, it was possible to derive the temperature and emission measure (EM) of the flaring plasma assuming an isothermal source. For larger events where more detailed spectra could be derived, a more accurate analysis was performed by fitting the spectra assuming various thermal and nonthermal sources. These results are compared to the diagnostics derived from AIA images. To this aim, the Differential EmissionMeasure (DEM) was reconstructed from AIA observations to infer plasma temperatures and EM in the flaring regions. Combined with the the relative timing between the emission seen by STIX and AIA, this allows us to get deeper insight into the flare energy release and transport processes.
Geoclimatic, demographic and socio-economic determinants of the Covid-19 prevalence
Authors: Demongeot Jacques , Oshinubi Kayode , Rachdi Mustapha , Seligmann Herve
Published: March 2021

We propose a panorama of already known Covid-19 determinants and some other new factors depending on three families of variables, i.e., geoclimatic (like temperature or elevation), demographic (like population density or median age) and socio-economic (like Gini' index or health expenditures as percentage of GDP) parameters. The influence of these determinants differs between the first and the second wave and we give some explanation of this phenomenon, which takes into account various geographical, political and biological characteristics of the populations concerned by the Covid-19 outbreak.

 

 

 

 

 

 

 

 

What do you want to do ?

New mail
Experimental rooftop rainwater harvesting by shallow well infiltration – A case study from the Duna-Tisza Interfluve, Hungary
Authors: Szabó Zsóka , Pedretti Daniele , Masetti Marco , Ridavits Tibor , Csiszár Endre , Mádl-Szőnyi Judit
Published: March 2021

In the Duna-Tisza Interfluve area, groundwater levels have declined significantly in the last decades, due to anthropogenic activities (e.g. water abstraction, canalization, and forestation) and climate change. In the past, several replenishment plans have been prepared, involving large, cross-regional technical investments, but have not been implemented due to the lack of adequate financial resources and environmental concerns. The aim of this study is to demonstrate a local scale solution by experimental research, which has several environmental and economic benefits and could contribute to ease the water shortage of the area.
Three approaches were used during the experimental research: (i) on-site field observations and measurements, (ii) time series analyses of the monitored data and (iii) transient numerical simulations to understand on-site processes. A field experiment was set up to lead rainwater from the roof of a family house to the dug well in the yard. Furthermore, two observation wells were established where the water level, temperature and electrical conductivity were recorded every half hour. Water samples were taken from the dug well and the monitoring wells for laboratory measurements. Precipitation was measured on a daily basis. The effects of shallow water injection on water level and water quality have been monitored for a year and the project is planned to be continued for at least one more year. In the second step, geomathematical methods have been applied to analyze time-series data and assess the effects of injected water on water levels and water quality. Moreover, a transient MODFLOW model was built (i) to evaluate the impact of the injected roof water on the groundwater level, (ii) to separate the influence of natural infiltration from the injected water, and (iii) to better understand the seasonal differences related to artificial and natural infiltration processes.
The obtained results can help to understand the effects of rainwater harvesting through shallow well infiltration, provide background information for further numerical simulations and contribute to expand the design of similar systems on settlement and regional level. In the Duna-Tisza Interfluve, rooftop rainwater harvesting and Managed Aquifer Recharge can be effective tools for climate change adaptation and increasing groundwater resilience.

This research is part of a project that has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 810980.
Biogeochemical carbon transformations in a drained coastal peatland of the southern Baltic Sea: An isotope and trace element perspective
Authors: Jenner Anna-Kathrina , Schmiedinger Iris , Kallmeyer Jens , Gutekunst Cordula , Jurasinski Gerald , Böttcher Michael Ernst
Published: March 2021

Peatlands serve as important ecosystems since they store a substantial fraction of global soil carbon. Through draining the internal biogeochemical processes may be changed impacting the transformation of stored carbon and plant material. Pristine peatlands are primarily associated with methanogenic and iron-cycling conditions, however, minor sulfur cycling may contribute to carbon mineralization in these ecosystems depending on the amount of atmospheric sulfur deposition and accumulation. In near coastal peatlands the element budget may be altered through natural or artificial flooding by brackish/marine waters. When introducing sulfate-bearing solutions, the concentrations of electron acceptors for anaerobic mineralization or organic matter increase when compared to fresh water conditions. The investigated area is planned to be flooded by Baltic Sea coastal waters in the near future.

Here we present results from a study from a drained peatland located in the southern part of the Baltic Sea. In the past the area was agriculturally used as grassland. Soil cores were retrieved along a transect perpendicular to the coast line for (isotope) biogeochemical analyses of pore water and solid phases. Analyses included the CNS composition of soils, and dissolved major elements, nutrients, sulphide, trace metals and stable isotopes of water, DIC, and sulfate (H, O, C, S). Furthermore, acid-extractions of metals were carried out to identify zones of dissolution and formation of authigenic phases. For quantification of microbial sulphate reduction rates (SRR) additional cores were retrieved and SRR were measured in whole-core incubations. 

The pore water isotopic composition is close to the local meteoric water line at the German Baltic Seas coast line. Concentration and stable isotope composition of DIC indicate mineralization of C3 type organic matter. Pore water trace metals content indicates the importance of anaerobic mineralization for release of metals into the pore and surface waters.

 

Acknowledgement: This study is supported by the DFG research training group BALTIC TRANSCOAST and Leibniz IOW.
Fast Plasma Flows Downstream of the Bow Shock Using MMS: Correlations and Generation Mechanisms
Authors: Raptis Savvas , Karlsson Tomas , Plaschke Ferdinand , Kullen Anita , Lindqvist Per-Arne
Published: March 2021

Fast plasma flows (magnetosheath jets) are localized and transient dynamic pressure enhancements found downstream of the Earth’s bow shock, in the magnetosheath region. They can be attributed to density and/or density enhancements and they are an energetic manifestation of the solar wind-magnetosphere coupling. They have been associated to several phenomena such as magnetopause reconnection, direct magnetosphere plasma inflow and the energization of the outer radiation belt electrons.

In this work, we are investigating the properties of a dataset of 9196 jets found by Magnetospheric Multiscale (MMS) from 09/2015 to 09/2020. These jets are classified into different classes based on their associated bow shock configuration. From the full dataset, about 300 jets are distinguished by being in very close proximity to a bow shock transition.

This subset of jet is then carefully pre-processed and statistically analyzed, providing information regarding the likelihood of existent (bow shock ripples, SLAMS penetration) and newly proposed (magnetic reconnection, magnetic islands) generation mechanisms for these jets. The initial results of these events support the pre-existing generation mechanism while giving indications to other possible effects that may take place.
Surface- and deep-water response to the Early Aptian OAE 1a in the western Tethys
Authors: Bottini Cinzia , Giraldo-Gómez Victor M. , Petrizzo Maria Rose , Erba Elisabetta
Published: March 2021

The Cretaceous was punctuated by interludes of widespread deposition of organic-rich sediments (black shales) in the oceans and epicontinental seas, named Oceanic Anoxic Events (OAE)s, representing major alterations in the global carbon budget. The early Aptian OAE 1a (ca. 120 Ma) coincided with a global paleoclimatic and paleoenvironmental perturbation which lasted for ca. 1.1 Myrs probably triggered by volcanogenic CO2 emissions associated with the emplacement of the Ontong Java Plateau. To date, there is a comprehensive characterization of OAE 1a paleoceanographic conditions and paleoecology of surface-waters while less information is available for bottom-water evolution. In this regard, benthic foraminifera are ideal to characterize deep-water oxygen levels and the organic carbon flux. We present a high-resolution study of benthic foraminiferal assemblages across OAE 1a in the Cismon Core (western Tethys, Lombardy Basin, Northern Italy). Contrarily to many sites, the Cismon Core yields benthic foraminifera also in the Selli Level thus providing information about deep-water conditions during OAE 1a. Our data are indicative of fluctuations in bottom-water oxygenation and organic-matter flux to the sea-floor prior to, during and after OAE 1a. The integration of the new benthic foraminiferal data with calcareous nannofossil and planktonic foraminiferal datasets is here used to produce a model of surface- to bottom-water paleowater evolution through the latest Barremian-early late Aptian. In particular, the new data show coeval changes in bottom- and surface-waters conditions prior to and at the onset of OAE 1a. Anoxia was reached during the core of the negative carbon isotope anomaly, under maximum warming and higher surface-water fertility. Conversely, the repopulation of benthic foraminifera postponed the plankton recovery. Benthic foraminifera data at Cismon show, for the first time, evidence of a repopulation event during the OAE 1a suggestive for a slight increase in the supply of oxygen to the seafloor during the Selli Level deposition.
Further validation of an open-source low-cost GNSS-R remote sensor for coastal sea level altimetry
Authors: Fagundes Manuella , Geremia-Nievinski Felipe
Published: March 2021

Contemporary sea level rise renders tide gauging essential in support of adaptation and mitigation strategies and to minimize its economic and societal impacts. Global Navigation Satellite System Reflectometry (GNSS-R) has been widely demonstrated for coastal sea level monitoring. One particular configuration of GNSS-R, called GNSS multipath reflectometry (GNSS-MR), is based on the combined tracking of direct and reflected radio waves against a single signal replica. The most common observable in GNSS-MR is the signal-to-noise ratio (SNR), which records the constructive/destructive interference pattern arising from the superposition of the two coherent ray paths. Recently we reported the development of a complete hardware and software system for SNR-based GNSS-R. We made it freely available as open-source based on low-cost commercial off-the-shelf components. We have deployed multiple working units of the sensor in the field, where they have operated uninterruptedly 24/7 for years, having resisted severe weather conditions. Initial validation was done by a lake (30.0277° S, 51.2287° W) for 317 days by comparison to a co-located radar-type tide gauge. Statistics confirmed that the sensor can retrieve water level with a very high correlation (0.989) and centimeter-level RMSE (2.9 cm). Here we report further coastal validation results of our GNSS-R sensor. The experiment was setup in a port (28.232019° S, 48.651064° W) with several co-located tide gauges within 100-m distance, including a radar sensor with 5-minute update interval and millimeter numerical resolution. We analyzed the time series of one week (June 19-25, 2019), and found a correlation of 0.885 and RMSE of 8.0 cm. We should emphasize this is the instantaneous sea level results and results for daily mean sea level would be improved. Although the location is sheltered from breaking waves, wind-driven waves are much greater, compared to the initial lake experiment. The increased surface roughness affects the coherence of radio wave reflections, which may eventually hamper the interferometric superposition principle, essential in GNSS-MR. This is part of ongoing validation efforts to quantity how correlation and RMSE in sea level altimetry are degraded due to the above error sources.
Reconstruction of the last three millennia South American Monsoon variability over the Amazon basin using speleothem isotope records 
Authors: Della Libera de Godoy Marcela Eduarda , Novello Valdir F. , Cruz Francisco William
Published: March 2021

South American Monsoon System (SAMS) and its main feature, the South American Convergence Zone (SACZ) are responsible for the major distribution of moisture in South America. The current work presents a novel high-resolution oxygen isotope record (δ18O) based on speleothems from southwest Amazon basin (Brazil), right at SAMS' core region and SACZ onset, where there is still a gap of high resolution paleoclimate records. The novel δ18O record presents an average of 3 year-resolution, composed by 1344 stable isotope analysis performed in two speleothems with a well-resolved chronology (37 U/Th ages) with average errors <1%. This work aims to describe the rainfall variability of the core region of the South American monsoon for the last 3k years and to take a broader look at precipitation patterns over Amazon basin. The Rondônia δ18O record shows three main stages throughout this time period. The first is from -1000 to ~400 CE, where it’s in accordance with most of other paleorecords from the Amazon basin. the second segment  is from ~400 to 1200 CE, when there is a continuous increase in the δ18O record until it reaches its highest values around 850 CE during the MCA (800-1200 CE), which is in accordance with western Amazon records, whilst the record in eastern Amazon presents an opposite trend. Thus, a precipitation dipole over Amazon emerges from ~400 CE onwards, majorly triggered by anomalous climate changes such as MCA, where western (eastern) Amazon is drier (wetter). During LIA (1450-1800 CE), on the other hand, Rondônia record presents its lowest values, also agreeing with western records and with records under the influence of SACZ whilst on eastern Amazon a drier period is established. Therefore, with this novel paleoclimate record located at the core region of SAMS, it's possible to evidence the dynamics of the precipitation dipole over the Amazon region, as well as understand the SACZ intensity variations.
Subduction zone heterogeneity observed across the magnitude spectrum for megathrust earthquakes
Authors: Bilek Susan , Morton Emily
Published: March 2021

Observations from recent great subduction zone earthquakes highlight the influence of spatial geologic heterogeneity on overall rupture characteristics, such as areas of high co-seismic slip, and resulting tsunami generation.  Defining the relevant spatial heterogeneity is thus important to understanding potential hazards associated with the megathrust. The more frequent, smaller magnitude earthquakes that commonly occur in subduction zones are often used to help delineate the spatial heterogeneity.  Here we provide an overview of several subduction zones, including Costa Rica, Mexico, and Cascadia, highlighting connections between the small earthquake source characteristics and rupture behavior of larger earthquakes.  Estimates of small earthquake locations and stress drop are presented in each location, utilizing data from coastal and/or ocean bottom seismic stations.  These seismicity characteristics are then compared with other geologic and geophysical parameters, such as upper and lower plate characteristics, geodetic locking, and asperity locations from past large earthquakes.  For example, in the Cascadia subduction zone, we find clusters of small earthquakes located in regions of previous seamount subduction, with variations in earthquake stress drop reflecting potentially disrupted upper plate material deformed as a seamount passed.  Other variations in earthquake location and stress drop can be correlated with observed geodetic locking variations. 
Heterogeneous uptake of NH3 on ambient PM2.5 in Beijing and Shijiazhuang: Possible influence of aerosol acidity
Authors: Liu Yongchun , Feng Zeming , Zhan Junlei , Bao Xiaolei
Published: March 2021

Ammonium salts (NH4+) is the important component of PM2.5 and has a significant impact on air quality, climate, human health, and natural ecosystems. The contribution of NH4+ to PM2.5 is increasing at urban sites. Ammonia (NH3) with global emissions estimated at greater than 33 Tg(N) Yr-1 is the only precursor of particulate NH4+ in the atmosphere. Thus, it is important to understand the conversion kinetics from NH3 to NH4+ in the atmosphere. However, the uptake coefficient of NH3 (γNH3) on aerosol particles are scarce at the present time. In this work, we reported the γNH3 on ambient PM2.5 in Beijing and Shijiazhuang in China. The γNH3 values on ambient PM2.5 are (1.13±12.4)×10-4 and (6.88±40.7)×10-4 in Shijiazhuang and Beijing, respectively. They are significantly lower than those on sulfuric acid droplet (0.1-1), aqueous surface (~5×10-3-0.1) and acidified secondary organic aerosol (~10-3-~10-2), while are comparable with that on ice surface (5.3±2.2 ×10-4) and on sulfuric acid in the presence of organic gases (2×10-4-4×10-3). An annual increase of γNH3 in the statistic sense is observed and the possible reason related to the aerosol acidity has also been discussed.
Living Well Within Planetary Limits: is it possible? And what will it take?
Authors: Steinberger Julia
Published: March 2021

This talk will report on the multiple research streams resulting from the Living Well Within Limits project. The Living Well Within Limits project investigates the energy requirements of well-being, from quantitative, participatory and provisioning systems perspectives. In this presentation, I will communicate individual and cross-cutting findings from the project, and their implications for the engineering research community. In particular, I will share our most recent results on global energy footprint inequality, implications of redistribution, as well as modelling the minimum energy demand that would provide decent living standards for everyone on earth by 2050. I will show that achieving low-carbon well-being, both from the beneficiary (“consumer”) and supply-chain (producer) sides, involves strong distributional and political elements. Simply researching this area from a technical, social or economic lens is insufficient to draw out the reasons for poor outcomes and most promising avenues for positive change. I thus argue for the active engagement of the research community.
Capon’s method for planetary magnetic field analysis 
Authors: Töpfer Simon , Narita Yasuhito , Heyner Daniel , Kolhey Patrick , Motschmann Uwe
Published: March 2021

Minimum variance distortionless projection, the so-called Capon method, serves as a powerful and robust data analysis tool when working on various kinds of ill-posed inverse problems. The method has not only successfully been applied to multipoint wave and turbulence studies in the context of seismics and space plasma physics, but it is also currently being considered as a technique to perform the multipole expansion of planetary magnetic fields from a limited data set, such as Mercury’s magnetic field analysis. The mathematical foundations and the practical application of the Capon method are discussed in a rigorous fashion by extending its linear algebraic derivation in view of planetary magnetic field studies. Furthermore, the optimization of Capon’s method by making use of diagonal loading is considered.
Quantifying the ITCZ using wind convergence
Authors: Elsemüller Lea , Goswami Bedartha
Published: March 2021

The intertropical convergence zone (ITCZ) expresses itself as a band of strong convection around the equator with associated heavy precipitation. The ITCZ migrates annually to the warmer hemisphere, and the extent to which it ventures away from the equator varies from year to year and across the different oceans and continents. These variations drastically affect rainfall and droughts in the equatorial area and beyond.Till now, various approaches have been proposed to quantify the ITCZ, e.g. based on maximum precipitation or energy budgets. However, a robust quantifier of the actual convergence of surface winds around the equator is still lacking. Here, we propose to quantify ITCZ mid position with a fundamental and intuitive definition using surface wind data and wind convergence only. We use surface wind data from ERA5 reanalysis at 0.25 degree grid resolution as a proxy for calculating the ITCZ mid position on a global scale. Given the u and v components of the wind we calculate the convergence of the windfields around the equator between 20° North and 20° South. We define the latitudinal ITCZ mid position as the maximum convergence on each longitude. We then validate our approach by comparing it to the ITCZ location as given by existing ITCZ position proxies. We also look at characteristics of the ITCZ width to learn more about the influence of wind fields on the extent of the ITCZ. Our results reveal the interannual variability and trends in the ITCZ in the last half century. It also highlights the different characteristics of the ITCZ over the different oceans and continents.
Recurrent global carbon cycle disturbances during the Aalenian: Evidence from France and Chile
Authors: Fantasia Alicia , Adatte Thierry , Spangenberg Jorge E. , Mattioli Emanuela , Bernárdez Enrique , Thibault Nicolas , Krencker François-Nicolas , Bodin Stéphane
Published: March 2021

The Jurassic was punctuated by several episodes of abrupt environmental changes associated with climatic instabilities, severe biotic crisis, and perturbations of the global carbon cycle. Over the last decades, the Toarcian Oceanic Anoxic Event (Early Jurassic, ~183 Ma) and the early Bajocian Event (Middle Jurassic, ~170–168 Ma) have attracted much attention because they represent such episodes of global and severe environmental change. Bracketed in between the Toarcian and the Bajocian, the Aalenian stage (Middle Jurassic, ~174-170 Ma) has received less attention, although there is some evidence from Tethyan and Boreal records that it was a time of environmental changes marked by marine biotic turnovers. The lack of knowledge about the Aalenian palaeoenvironments leaves a gap in our understanding of the wider context of the Toarcian and Bajocian events and hence of environmental feedback mechanisms surrounding Mesozoic carbon cycle perturbations. In this study, we provide a high-resolution, biostratigraphically well-defined carbon isotope records (δ13Corg and δ13Ccarb) combined to Rock-Eval data for the upper Toarcian–lower Bajocian interval from two expanded marl/limestone alternation successions from France (French Subalpine Basin) and Chile (Andean Basin). The comparison with available records from the Tethyan and Boreal domains highlights that medium-term δ13C fluctuations are reproducible across different palaeoceanographic settings from both hemispheres and between different carbon substrates. The new high-resolution dataset highlights the complexity of the Aalenian δ13C record, including previously identified δ13C shifts and hitherto undescribed fluctuations. This study provides one of the most expanded high-resolution chemostratigraphic reference records for the entire Aalenian stage, and shows compelling evidence from both hemispheres that it was a time marked by recurrent perturbations to the global carbon cycle and environmental changes.

 
Focal mechanism of intermediate depth earthquakes in the Alboran Sea (Western Mediterranean)
Authors: López-Sánchez Carolina , Buforn Elisa , Mattesini Maurizio , Cesca Simone , Cantavella Juan Vicente , Lozano Lucia , Udías Agustín
Published: March 2021

One of the characteristics of the seismicity in the Ibero-Maghrebian region is the occurrence of intermediate depth earthquakes (50<h<100 km), their largest concentration located at the western part of the Alboran Sea, with epicenters following an NNE-SSW alignment. In this study, we have relocated over 200 intermediate depth earthquakes (M≥3) occurred in this region in the period 2000-2020, using a non-linear probabilistic approach (NonLinLoc algorithm) together with a recent regional 3D tomography lithospheric velocity model for the Alboran-Betic Rif Zone. Maximum likelihood hypocenters confirm the NNE-SSW distribution in a depth range between 50 and 100 km. We have determined the focal mechanisms of 26 of these earthquakes with magnitudes (mb) greater than 3.9. We first derived focal mechanisms using the P-wave first motion polarity method and then performed a moment tensor inversion, using a probabilistic inversion approach based on the simultaneous fit of waveforms and amplitude spectra of P and S phases. We performed an accurate resolution study, by repeating the inversion using different 1-D velocity models and testing different moment tensor (MT) constraints: a full moment tensor, a deviatoric moment tensor and a pure double couple (DC). Misfit values are similar for different MT constraints. Most solutions have a non-DC component larger than 30%. This may be due to the tectonic complexity of the region and the use on the inversion of 1-D Earth model. The DC components obtained from the inversion show different orientations of the nodal planes. A first group of events to the northern part with epicenters inland on south Spain have horizontal tension axes in NE-SW direction. A second group of earthquakes with epicenters off-shore, but close to the Spanish coast, presents near-vertical pressure axes. The third group, formed by deeper earthquakes, with epicenters on the center of the Alboran sea have dip slip focal mechanisms of either normal or reverse motion with planes either vertical or dipping 45º plane oriented in NNE-SSW direction, approximately the same orientation as the alignment of their epicenters. The distribution of these intermediate depth earthquakes and their focal mechanisms evidence the seismotectonic complexity of the region related with a possible subduction.
Risks associated with the presence of cyanide in waste materials in an abandoned gold mine, Panama
Authors: González Valoys Ana Cristina , Monteza-Destro Tisla , Esbrí José María , Vargas-Lombardo Miguel , Garcia-Ordiales Efrén , Arrocha Jonatha , Jiménez-Ballesta Raimundo , Garcia-Navarro Francisco Jesús , Higueras Pablo
Published: March 2021

The inadequate treatment of waste materials in mine tailings, the closure stage not carried out correctly, carries risks due to the residues of potentially toxic elements (PTEs) that it may contain. In Panama, environmental regulations are recent, and even so the regulations are not strictly enforced, leaving a problem for the adjacent communities. Such is the case of the Remance Gold Mine, in Veraguas, Panama; this area has been exploited intermittently for over a hundred years, by different companies; the last period of exploitation was between 1989 and 1999, through a cyanidation process to extract the precious metal. Currently three tailing dams with mining waste are exposed to climatic conditions such as rain and wind, in addition to this, within the mine area and its surroundings live peasants who carry out subsistence activities such as agriculture and livestock. The purpose of this study was to evaluate the remaining potentially toxic elements and the persistence of cyanide in the tailings, and whether the remaining quantity represents a risk to human health and the environment, according to current environmental regulations in Panama and America. For this purpose, samples have been taken from the tailings and adjacent areas that could be directly related to the cyanidation process, geochemical analysis such as pH, CEC, conductivity, organic matter, potentially toxic elements and total cyanide have been carried out. The most concerning aspects of the results obtained here have been the contents of Ba (between 55 and 610 mg kg-1), Zn (between 12 and 153 mg kg-1), Sb (between 0.6 and 25.5 mg kg-1) and Hg (between 0.1 and 3.2 mg kg-1), which, according to the criteria of land use quality standards in Panama and American countries, correspond to values above the permissible limits for agricultural and residential land use. Meanwhile the levels of As (between 17.3 and 5030 mg kg-1) and Cu (between 5.4 and 403 mg kg-1) are higher than the legally established values for industrial land use. Far more significant are the values for total cyanide (between 1.4 and 518 mg kg-1), revealing the persistence of this chemical over time. These cyanide values are far higher than those reported in the literature for solid tailings from an abandoned gold mine and the values for gold mine tailings in the Americas, thus representing a serious threat to the environment.
Climate change impact on the hydrometeorological drought propagation 
Authors: Meresa Hadush , Murphy Conor , Fealy Rowan
Published: March 2021

Hydrometeorological droughts are complex hazards that cover wide areas with typically slow-onset and can affect different social, economic, environmental sectors at different spatial and temporal scales. However, it is challenging to investigate changes in hydrometeorological drought and their propagation from precipitation deficit, to soil moisture, discharge and groundwater deficits and to ascertain to what extent climatic change may affect drought characteristics (e.g. magnitude, frequency and duration). This research explores changes in hydrometeorological drought characteristics and their propagation from meteorological to hydrological drought states using climate model simulations from CMIP6 to force a conceptual hydrological model. Using a sample of 30 catchments in Ireland, we examine changes in hydrometeorological drought using standardised indices of precipitation (SPI), soil moisture deficits (SPEI), runoff (SRI) and baseflow (SBI). We find that downscaled CMIP6 projections are poor at capturing droughts at shorter timescales, however performance increases depending on bias correction technique and drought accumulation period. Largest uncertainties in drought projections emanate from climate models, outweighing the role of hydrological model parameter uncertainty, bias correction and emissions scenarios. Projected changes in drought characteristics strongly covary for SPI and SPEI, however covariation in changes is weaker for SRI and SBI. The propagation of meteorological to hydrological drought increases over time, with proportional increases for moderate, severe and extreme droughts. Across the catchment sample the average lag time between meteorological and hydrological drought occurrence in the baseline period is 3-5 months, with lag times likely to increase with climate change. Therefore, results suggest that while the propagation of meteorological droughts to hydrological events (SRI/SBI), increases, the time taken for precipitation anomalies to become apparent in hydrological variables increases. Such changes in drought propagation need to be considered in adaptation planning.
Investigating nutrient controls over microbial activity in tropical soils
Authors: Fuchslueger Lucia
Published: March 2021

The Amazon rainforest is an important sink for atmospheric CO2 counteracting increased emissions from anthropogenic fossil fuel combustion and land use change storing large amounts of carbon in plant biomass and soils. However, large parts of the Amazon Basin are characterized by highly weathered soils (ultisols and oxisols) with low availability of rock-derived phosphorus (and cations), which are mostly occluded in soil or bound in organic matter. Such low phosphorus availability is thought to be (co-)limiting plant productivity. However, much less is known whether low phosphorus availability influences the activity of heterotrophic microbial communities controlling litter and soil organic matter decomposition and thereby long-term carbon sequestration in tropical soils.

In tropical soils high temperature and humid conditions allow overall high microbial activity. Over a larger soil phosphorus fertility gradient across several Amazonian rainforest sites, at low P sites almost 40 % of total P was stored in microbial biomass, highlighting the competitive strength of microorganisms and their importance as P reservoir. Across all sites soil microbial biomass was a significant predictor for soil microbial respiration, but mass-specific respiration rates (normalized by microbial biomass C) rather decreased at higher soil P. Using the incorporation of 18O from labelled water into DNA (i.e., a substrate-independent method) to determine microbial growth, we found significantly lower microbial growth rates per unit of microbial biomass at higher soil P. This resulted in a lower microbial carbon use efficiency, at a narrower C:P stoichiometry in soils with higher P levels, and pointed towards a microbial co-limitation of phosphorus and carbon at low soil P levels. Furthermore, data from a multi-year nutrient manipulation experiment in French Guiana and from short-term lab incubations suggest that microbial communities thriving at low P levels are highly efficient in taking up and storing added P, but do not necessarily respond with increased growth.

Soil microbial communities play a crucial role in soil carbon and phosphorus cycling in tropical soils as potent competitors for available P. They also play an important role in storing and buffering P losses from highly weathered tropical soils. The potential non-homoeostatic stoichiometric behavior of microbial communities in P cycling is important to consider in soil and ecosystem models based on stoichiometric relationships.
Using 1D-modelling to study Arctic chlorine activation, transport and VOC oxidation during Arctic springtime
Authors: Ahmed Shaddy , Thomas Jennie , Tuite Katie , Stutz Jochen , Flocke Frank , Orlando John , Hornbrook Rebecca , Apel Eric
Published: March 2021

Polar halogen chemistry has long been known to be active, especially in spring, and is known to have an important influence on the lifetime of some volatile organics, ozone and mercury. Our understanding of polar halogen chemistry is changing, including the recognition that there is active chlorine, bromine and iodine chemistry occurring within the polar boundary. Recently, very high concentrations of molecular chlorine (Cl2) were recorded at Utqiaġvik, Alaska during the Ocean-Atmosphere-Sea Ice-Snowpack (OASIS) campaign in spring 2009, with a correlation between daytime Cl2 mixing ratios, ozone concentrations and sunlight. However, the chlorine radical concentrations inferred from these Cl2 measurements, with the observed VOC abundances and lifetimes, cannot yet be fully explained via chemical box modelling alone. To explain these discrepancies, modelling that includes surface snow Cl2 formation processes, subsequent atmospheric chemistry and vertical mixing is needed and is an essential tool in quantifying impacts on VOC lifetimes and the role of vertical mixing in controlling boundary layer chemistry.

In this work, we use a one-dimensional atmospheric chemistry and transport model (Platform for Atmospheric Chemistry and Transport in 1-Dimension, PACT-1D) to investigate surface Cl2 production from snow, snowpack recycling, vertical transport and reactivity with VOCs at Utqiaġvik, Alaska during the OASIS campaign. We implement a new surface parameterization of chlorine emissions from the snowpack based on the solar irradiance and surface ozone levels and consider the role of vertical mixing processes. By considering both production and transport mechanisms, we are able to obtain good agreement between the model predicted Cl2 mixing ratios and observations at 1.5 meters. The model predicts that nearly all reactive chlorine resides within the lowest 15 m of the boundary layer, resulting in increased chemical reactivities and oxidation rates in the lowest part of the atmosphere. VOC abundances near the surface that are co-located with elevated chlorine can be explained by downward mixing of VOCs from aloft, which replenishes VOCs from free tropospheric reservoirs. The proposed surface emission parameterization of chlorine in this work could be used to develop current 3D numerical models in order to explore chlorine emissions and reactivity over the entire Arctic as well as the effects of future Arctic climate scenarios on atmospheric halogen chemistry.
Simulation of indoor radon and ventilation systems in a scale model room to assess the contribution of high activity building materials to indoor radon. 
Authors: Tuccimei Paola , Lucchetti Carlo , Galli Gianfranco , Soligo Michele
Published: March 2021

Indoor radon accumulation is considered the main source of human exposition to ionizing radiation. The main sources of indoor radon are soil gas, the building materials and tap water, especially when they are enriched in 226Ra and 232Th, which are the precursors of main radon isotopes: 222Rn and 220Rn, respectively.

In the frame of RESPIRE (Radon rEal time monitoring System and Proactive Indoor Remediation), a LIFE project funded by European Commission, a scale model-room of 62 cm x 50 cm x 35 cm (inner length x width x height) was manufactured with a very porous and highly radioactive lithoid ignimbrite to evaluate the contribution of building materials to indoor radon accumulation, simulating the effect of a ventilation system to reduce indoor radon levels.

A series of experiments was designed where either outdoor air was introduced in the model room or indoor air was extracted from the room, at different flow rates (from 0.15 to 0.82 liters per minute) to evaluate how air exchange and mixing affect indoor radon level. In the first group of tests, the introduction of outdoor air strongly reduced indoor radon concentration, with radon relative decrease directly proportional to the air flow. In the second set of experiments, the extraction of indoor air very moderately lowered radon levels. Finally, a modified version of Fick’s second law was used to model experimental data, describing how radon diffused through the very porous room walls under different experimental conditions.

 

 

 
“Perspicacity… and a degree of good fortune”: opportunities for revealing the natural world
Authors: Harrison R.Giles
Published: March 2021

Experimental science is now more possible and accessible than ever, due to the ready abundance of sensors and recording systems. However, as commercial development of sensors generally follows demand and profitability, most of the options are restricted to devices sensing the most commonly monitored physical quantities. A scientific need can therefore still arise - which Christiaan Huygens would no doubt recognise, and indeed confronted so ably - for an entirely new instrument. As for Huygens’ era, the role of the experimentalist includes seeking and exploiting the best method available for each scientific investigation. This includes modern advances in electronics, materials and production. I will describe some of my own work in atmospheric electricity to try to illustrate the continued value of this approach, in which scientific objectives have driven the design, development and deployment of new instruments for which there were no commercial options. Existing measurement infrastructures, for example surface meteorological observing systems and weather balloon networks, can be enhanced as a result, from embedding and including new sensors, instruments and devices.
Influence of Different Phases of Quasi-Biennial Oscillation on the Evolution of Polar Stratospheric Zonal Winds 
Authors: Ozturk Rahan , Demirhan Deniz , Unal Yurdanur , Topcu Sema
Published: March 2021

Stratospheric zonal winds are disturbed by tropospheric forced planetary waves which modulate the quasi-biennial oscillation (QBO) in the northern hemisphere during winter. QBO is the quasi periodic oscillation of zonal winds in the lower stratosphere with an average recurrence of 28 months. QBO is mainly characterized by zonal mean circulation in the equatorial and low latitudes of middle atmosphere. Investigations indicate that although QBO is an equatorial oscillation there is a strong correlation between QBO and stratospheric polar wind patterns. Additionally, westerly and easterly phases of QBO alter the strength of these winds differently. During the westerly phase of QBO, northern stratospheric zonal winds are stronger whereas the easterly phase coincides with the weaker stratospheric zonal winds.

In this study, easterly and westerly zonal winds at 30hPa for the latitudes between 5°S and 5°N which characterize the westerly (QBO-W) and easterly (QBO-E) phases of the QBO is examined using CMIP5 MPI-ESM-MR RCP4.5 scenario for the years between 2006 and 2099 for winter. It is found that climatic changes in the zonally asymmetric zonal wind characteristics in both phases of QBO modulates the polar stratospheric zonal winds differently. A prominent wave-1 structure in QBO-E phase and a wave-2 structure in QBO-W phase are apparent and effect the strength of the polar stratospheric zonal winds.

This study is a supported by TUBİTAK (The Scientific and Technology Research Council of Turkey), The Scientific and Technological Research Projects Funding Program, 1001.The project number is 117Y327.

 

 
Model-data comparison in a strongly eddying Eocene ocean
Authors: Nooteboom Peter , Baatsen Michiel , Bijl Peter , van Sebille Erik , Sluijs Appy , Dijkstra Henk , von der Heydt Anna
Published: March 2021

Simulations of the geological past using General Circulation Models (GCMs) are computationally expensive. Mainly because of the long equilibration time scales, most of these GCMs have ocean components with a horizontal resolution of 1° or coarser. Such models are non-eddying and the effects of mesoscale ocean eddies on the transport of heat and salt are parameterized. However, from present-day ocean modeling studies, it is known that eddying ocean models better represent regional and time-mean ocean flows compared to non-eddying models. At the same time, proxy data from sediment sample sites represent climate at specific locations. Hence, the coarse ocean resolution of typical palaeo-GCMs lead to a challenge for model-data comparison in past climates.

Here we present the first simulations of a global eddying Eocene ocean with a 0.1° (horizontal) resolution model, which are initialized and forced with data from a coarser resolution (1° horizontally) equilibrated coupled ocean-atmosphere GCM. We investigate the response of the model equilibrium state to the change in ocean resolution and the consequences this has for model-data comparison in the middle-late Eocene (38Ma). We find that, compared to the non-eddying model, the eddying ocean resolution of palaeomodels reduce the biases in both sea surface temperatures and biogeographic patterns which are derived from proxy data.