bluuebunny/crossref_metadata_2025 huggingface dataset:
Late Quaternary vegetation dynamics in interior Alaska revealed by sedimentary ancient DNA (sedaDNA) from lake sediment and unfrozen (loessic) archaeological sediments
Authors: Edwards Mary , Clarke Charlotte , Bigelow Nancy , Heintzman Peter , Potter Ben , Alsos Inger , Reuther Joshua
Published: March 2021

About 14,000 years ago, on the cusp of major environmental changes that affected the distribution of animals, vegetation cover and hydrology, humans entered interior Alaska for the first time.  A sedimentary ancient DNA (sedaDNA) record from a lake in the Tanana valley, which lies close to several of the oldest dated archaeological sites, documents plant community changes over the past ca. 15,000 years and makes an important contribution towards resolving late MIS-2 floristic composition of the northern, ice-free region of northwest North America.  Macroscopic charcoal and sediment properties provide further information on changes in climate and fire regimes.

For sedaDNA analysis, we amplified a short locus of the plant chloroplast genome in all samples, and a total of 167 vascular plant and 14 bryophyte taxa were detected in the lake sedaDNA record. A rich herbaceous flora, including taxa typical of open tundra habitats, dominates the record until ca. 14,000 cal yr BP; diverse grass taxa are present, and Salicaceae is recorded in every sample in this period. This flora continued (though with compositional changes) as a dominant element in the following period, which was also characterized by the presence of shrub and/or tree birch, and which ended with the establishment of coniferous forest ca. 10,000-11,000 yr BP. This last change is also reflected in sediment organic content, sedimentation rate, and the addition of a diverse range of shrubs, sub-shrubs, boreal forbs, spore-plants and aquatic macrophytes, all reflecting profound alterations in both terrestrial and lacustrine plant communities. Macro-charcoal is present in all floristic zones, with higher concentrations afterca. 14,000 yr BP, indicating that both deciduous and evergreen woody communities burned.  

This lake record provides a picture of key landscape-scale changes experienced by early human populations.SedaDNA results obtained from contemporaneous cultural and non-cultural layers at nearby archaeological sites in the Tanana Valley can provide further complementary information on natural resource use by early human communities in response to a changing environment. The loessal sediments at these archaeological sites present challenges to sedaDNA studies, including anthropogenic disturbance of the matrix, rootlet penetration, and unfrozen conditions for around four months of the year that may accelerate bacterial degradation and fragmentation of DNA. We present here some preliminary results from these archaeological localities.
The First STIX Coarse Flare Locations
Authors: Dickson Ewan ,   STIX team
Published: March 2021

The Spectrometer/Telescope for Imaging X-rays (STIX) on board Solar Orbiter (Krucker et al., 2020) uses an indirect imaging system to measure flare location, size and morphology. Pairs of tungsten grids create Moiré fringes on its coarsely pixelated CdTe detectors. Images are then reconstructed on the ground, using sophisticated imaging algorithms, after the data containing the counts in each pixel for 30 imaging detectors has been download. 

STIX therefore uses a dedicated sub-collimator to estimate a rough (within a few arcminutes), but unambiguous, flare location on board in near real time. The Coarse Flare Locator (CFL) consists of a single grid with a specific pattern which selectively illuminates pixels of a dedicated detector based on the source location. The correlation between the counts in the pixels of this detector, combined with sums of counts from the other detectors, and a look up table of pre-caculated expectations allows the location to be estimated promptly, within the constraints of on board processing. 

Using the downloaded measured counts in each pixel the coarse flare location can also be reconstructed on the ground. This allows for more sophisticated algorithms which require greater computational power than is available on board; greater flexibility as to which time and energy intervals are combined; and more careful background subtraction possible. 

The first estimates of STIX flare locations calculated using the STIX Ground Processing Software (GSW) from data taken during commissioning and subsequent Remote Sensing Checkout Windows are presented here. Comparisons are made to the expected active region and source locations, using data from several other instruments. 

References 

Krucker, S et al. The Spectrometer/Telescope for Imaging X-rays (STIX). Astronomy and Astrophysics, v. 642, Oct. 2020. DOI: 10.1051/0004-6361/201937362.
A first look at the SuperCam RMI images aboard Perseverance
Authors: Gasnault Olivier , Virmontois Cedric , Maurice Sylvestre , Wiens Roger C. , Le Mouelic Stephane , Bernardi Pernelle , Forni Olivier , Pilleri Paolo , Daydou Yves , Rapin William , Cais Philippe
Published: March 2021

Starting in February 2021, the Perseverance rover will characterize a new landing site, the Jezero crater on Mars, and assemble a returnable cache of samples [1]. Among the remote sensing instruments, SuperCam combines chemical, mineralogical and organic spectroscopy, sound recording and imaging [2, 3, 4]. SuperCam’s RMI (Remote Micro-Imager) provides pictures for local context and site imaging at high-resolution.

The 110-mm SuperCam telescope with a focal length of 563 mm allows to take color images of 2048x2048 pixels with a CMOS camera on a bandwidth from ~375 to ~655 nm. The images will be divided by a reference flat-field to correct the attenuation factor of ~5 due to vignetting. The diameter of the circular field-of-view is ~18.8 mrad. The angular size of the RMI pixels is slightly less than 10 microrads, and the effective image resolution is better than 80 microrads, which represents 0.24 mm at 3 m.

Images will be taken at the start and end of the SuperCam raster observations [3] and assembled into annotated mosaics, which will provide information on the nature of the targets at the scale of the SuperCam investigation. Images will also be taken to study remote outcrops. At the time of the conference, Perseverance will have been on Mars for 2 months. Although the first images of the RMI will be used to check the health of the instrument, we also hope to have a first view of the landing site by then.

References: [1] Farley K.A. et al. (2020) SSR, 216, 142. [2] Maurice S. et al. (in revision) SSR. [3] Wiens R.C. et al. (2021) SSR, 217, 4. [4] Maurice S. et al. (this issue). 
Soils training and research: Who's legacy?
Authors: Mezeli Malika , Evans Daniel , Jones Davey , Lawrenson Olivia , Haygarth Philip
Published: March 2021

Soils Training and Research Studentships (STARS) is a NERC and BBSRC funded Centre for Doctoral Training (CDT).  The consortium comprises of four universities and four research institutes from around England, Scotland and Wales who are collaborating to offer training to PhD students in soil science. The program offered forty PhD studentships over four cohorts, which started in 2016 and due to complete in 2022. The ambitious program aimed to address the under representation of soil science and graduates in UK higher education institutes.

The comprehensive CDT supports cross-institute participation which allows a sharing of resources both human and physical promoting a cross-disciplinary research environment. Students have received group training from experts across the respective establishments encouraging inter-institute collaboration and support. Centralised funding has supported a range of outside training from motion graphic skills to clowning in public to genomics and statistics and the production of video media products by students and staff communicating their research and knowledge. In addition, the managerial structure at STARS has allowed for easy access to professional and industry placements for students. By building upon the traditional PhD experience, STARS has been able to facilitate not only quality doctoral research but also graduates with the skill set and networks required by the next generation of soils scientists to help achieve the 2030 Sustainable Development Goals.

Collectively, the STARS consortium has amassed a vast range of soils research, knowledge, skills and training resources. To remain ambitious and forward focused our legacy project will bring together these resources and continue to work to build on the relationships forged under STARS and into the broader soil community.   These resources will be accessible to those outside of STARS and outside of the research community because resources that offer the tools to support healthy soils, clean water, access to healthy food is not our legacy, it is everyone’s.  The legacy we are left with will not only be comprised of our journal publications but our success in sharing our knowledge, translating our findings and being active participants in global dialogues.
Synergistic use of SMOS and Sentinel-3 for retrieving spatiotemporally estimates of surface soil moisture and evaporative fraction
Authors: Piles Maria , Pablos Hernandez Miriam , Vall-llossera Mercè , Portal Gerard , Sandric Ionut , Petropoulos George P. , Hristopulos Dionisis
Published: March 2021

Earth Observation (EO) makes it possible to obtain information on key parameters characterizing interactions among Earth’s system components, such as evaporative fraction (EF) and surface soil moisture (SSM). Notably, techniques utilizing EO data of land surface temperature (Ts) and vegetation index (VI) have shown promise in this regard. The present study presents an implementation of a downscaling method that combined the soil moisture product from SMOS and the Fractional Vegetation Cover provided by Sentinel 3 ESA platform.

The applicability of the investigated technique is demonstrated for a period of two years (2017-2018) using in-situ data acquired from five CarboEurope sites and from all the sites available in the REMEDHUS soil moisture monitoring network, representing a variety of climatic, topographic and environmental conditions. Predicted parameters were compared against co-orbital ground measurements acquired from several European sites belonging to the CarboEurope ground observational network.

Results indicated a close agreement between all the inverted parameters and the corresponding in-situ data. SSM maps predicted from the “triangle”  SSM showed a small bias, but a large scatter. The results of this study provide strong supportive evidence of the potential value of the investigated herein methodology in accurately deriving estimates of key parameters characterising land surface interactions that can meet the needs of fine-scale hydrological applications. Moreover, the applicability of the presented approach demonstrates the added value of the synergy between ESA’s operational products acquired from different satellite sensors, namely in this case SMOS & Sentienl-3. As it is not tight to any particular sensor can also be implemented with technologically advanced EO sensors launched recently or planned to be launched.

In the present work Dr Petropoulos participation has received funding from the European Union’s Horizon 2020 research and innovation programme ENViSIoN under the Marie Skłodowska-Curie grant agreement No 752094.
Projecting Future Air Quality Under Energy Transition Scenarios over the U.S. using Online-Coupled Models
Authors: Zhang Yang , Wang Kai , Schuch Daniel
Published: March 2021

 

Online-coupled meteorology-chemistry models provide powerful tools for more realistically simulation of current and future air quality with feedbacks between atmospheric composition and meteorology that cannot be considered in offline-coupled models. In this work, several state-of-science online-coupled models are applied to generate the best possible predictions of surface ozone (O3) and fine particulate matter (PM2.5) concentrations under current emission and climate conditions. Two ensemble methods are used to further reduce the model biases and errors including a simple ensemble mean based on an average of ensemble members, and a weighted ensemble mean based on the multi-linear regression. The skills of individual models and their ensembles are evaluated using available surface network data.  Compared to individual models and the simple ensemble mean, the weighted ensemble predictions based on the multi-linear regression perform the best overall for both O3 and PM2.5. The model with best performance is selected to apply for future years to project the changes in air quality under various energy transition scenarios to support the development of emission control strategies. These results illustrate the current capability of the online-coupled models and the potential of weighted ensemble in generating the best possible estimates of air pollutant concentrations under current and future atmospheric conditions. 
Transboundary human-water systems
Authors: Wei Jing , Elshorbagy Amin
Published: March 2021

Transboundary rivers flow across political boundaries, requiring riparian countries to share a complex network of environmental, economic, political, social and security interdependencies. Transboundary river fluctuates in both space and time, and have multiple and conflicting demands on its uses, which have often resulted in tensions between riparian countries. Conflict and cooperation is thus an emergent phenomena of this co-evolved human-water systems. The choice of cooperative or conflictive behaviours from riparian countries is not only related to the nature of the water issue itself, but it attains more to the political, cultural, institutional, and socioeconomic conditions of the upstream and downstream countries involved. Understanding of the feedback mechanism is thus needed to be able to develop the understanding of how different actors cake to cooperation of conflict and knowledge to manage it effectively. As part of Panta Rhei Synthesis book, this study provides case study of transboundary human-water system by reviewing knowledge of conflict and cooperation dynamic from various disciplines, existing models and frameworks developed.  
Seascape ecological view as a new insight of benthic foraminiferal community
Authors: Kitazato Hiroshi
Published: March 2021

Foraminifers secrete various chemicals for chamber walls. They are calcium carbonates such as calcite, aragonite, Mg-calcite, organic compounds for agglutinated chambers and/or organic cemented test walls.  Foraminiferal test walls basically form according to genetic information.  However, same test group is tended to gather at specific microenvironments.  For instance, turf shaped algal microhabitat such as coralline algae at rocky shore is composed of both frond and thallus parts as microhabitat.  Frond part is open space where fresh seawater moves inbetween one frond and the other.  Elphidium crispum, Pararotalia nipponica and Patellina corrugate and other calcareous foraminifers dwell at frond surface.  In contrast, thallus part is muddy and high concentration of organic matters.  The thallus part shows less oxygenated than frondal part as the space is close.  Microbial cascades are developed at thallus part.  Minor elements such as Mg or Sr are relatively high in sediment.  Soft-shelled forms such as Allogromia, gromiid, agglutinated forms and miliolids groups with high magnesian calcite tests flourish at the thallus part.

Microhabitat segregation and microenvironmental differences may cause similar biomineralization of benthic foraminiferal tests.  I would like to stress that micro-seascape should be important to characterize benthic foraminiferal assemblages.
Time to "Rewet the Swamp" – Application of Georgian Data Cube to Elucidate Drainage Patterns and Potential for Wet Agriculture and Forestry on Kolkheti Lowland
Authors: Matchutadze Izolda , Bakuridze Aliosha , Abuladze Ira , Shakarishvili Nana , Gvilava Mamuka
Published: March 2021

It was established recently that gravity drainage is inefficient on Kolkheti Lowland along the Black Sea coast of Georgia and that novel approaches are urgently recommend, such as implementing rewetting schemes to restore ecosystem services and enhance economic values of these areas through wet agriculture, biofuel production with native wetland species, and/or afforestation, to achieve sustainable outcomes in both ecologic and economic terms. Water Detection, Fractional Cover and Urbanization remote sensing tools, provided by Georgian Data Cube (comprising Landsat sensor Analysis Ready Data), developed recently with UNEP/GRID support, were applied on multi-year timescale basis for Kolkheti lowland to identify priority areas with high potential for rewetting. Water Detection tool allowed establishment of low effectiveness drainage areas, as demonstrated by high cumulative values for the presence of water, indicating water-logged areas as potential intervention sites for wet agroforestry. Water Detection combined with Fractional Cover tool allowed comparative analysis of non-photosynthetic vegetation and bare soil areas versus high water detection areas to single out those lands on the Kolkheti lowland, where drainage seems effective and dry agriculture is pursued versus those lands where drainage is not effective and dry agriculture is not actually happening. Urbanization tool can also be applied to detect human activities, such as agricultural activities, visualising those areas, which are subjected to active vegetation removal on an annual basis due to crop harvesting and those areas, where vegetation was not removed, staying vegetated most of the time, interpreted as abandoned agricultural lands. Regular patters combining non-use agricultural with cumulative water covered areas could thus help locate candidate sites for piloting wet agriculture on Kolkheti Lowland in Georgia. In addition to sustainable economic practices, rewetting could certainly benefit core ecological areas of Kolkheti Lowland, protected by both national designation as Kolkheti National Park and international designation as Central Kolkheti Ramsar Site.
African Epeirogeny in the Geomorphic Record
Authors: O'Malley Conor , White Nicky , Roberts Gareth , Stephenson Simon
Published: March 2021

A range of geological evidence documents the growth of African topography as a result of sub-plate support throughout Cenozoic times. Recent studies used inverse modeling of drainage networks governed by the linear stream power law to quantify the spatio-temporal history of uplift and erosion across the continent. Here, we test predictions of this uplift rate history by applying it as tectonic forcing to naturalistic landscape evolution simulations. These simulations parameterise dynamic drainage reorganisation, track sedimentary flux, and permit variable erodibility, none of which are feasible in inverse models. Modelled topography, river profiles, drainage planforms and sedimentary flux patterns broadly match observations. We test the sensitivity of forward model prediction to variations in erodilibity by employing spatio-temporally variable precipitation rate. Forward model predictions are relatively robust to even large excursions, suggesting landscapes contain internal feedbacks which modulate these effects and permit close recovery of the geomorphic record of uplift. Wavelet power spectral analysis reveals observed African river profiles are self-similar at wavelengths >~ 100 km, meaning longest-wavelength features have the highest amplitudes. At shorter wavelengths, spectral slopes increase, implying sharper features are generated only at wavelengths <~ 100km. Synthetic fluvial profiles recovered from simple landscape evolution models driven by uplift forcing obtained from inverse modeling of observed river profiles are self-similar across all wavelengths. This self-similarity solely reflects the tectonic forcing applied. When noise in erodibility or uplift rate forcing is added to forward simulations, power spectra of resulting fluvial profiles more closely approximate spectra of observed profiles. Thus sharp signals in observed river profiles arise from factors which do not correlate between neighbouring tributaries, e.g. lithological constrasts, self-forming hydraulic shocks, or human alteration. The recoverability of regional uplift from observed fluvial profiles is made possible by the fact that most topographic power is generated by regional uplift and resides at long-wavelengths.
A Revised Complex Refractive Index Model for Inferring the Permittivity of Heterogeneous Concrete Models
Authors: Zadhoush Hossain , Giannopoulos Antonios , Giannakis Iraklis
Published: March 2021

The estimation of the bulk permittivity of heterogeneous mixtures is of great interest for many Ground Penetrating Radar (GPR) and electromagnetic sensing applications [1], [2]. The most used method for estimating the bulk permittivity is the Complex Refractive Index Model (CRIM). The simplicity of this method is one its advantages however, the accuracy of the permittivity estimation has not been tested. Here, the CRIM model’s shape factor is examined and optimised in order to achieve a more accurate concrete bulk permittivity estimation. The concrete components are aggregate particles, cement particles, air-voids and moisture content; and they are randomly distributed with different volume percentages to produce various combinations. These combinations are modelled using the Finite-Difference Time-Domain (FDTD) method as it is an accurate and computationally efficient method [3]. The numerical modelling is then used to predict the bulk permittivity allowing to fine-tune CRIM model’s shape factor. The models are modelled in 3D and a GSSI-like antenna structure is used as the transmitting source [4]. The permittivity estimation uses an accurate time-zero method, which increases the accuracy of the estimated bulk permittivity hence, the shape factor [5], [6]. The results have shown that the optimised CRIM model over-performs the original CRIM model shape factor therefore, a better and more accurate bulk permittivity estimation is achieved for concrete mixtures.

 

References

[1] Daniels, D. J., (2004), Ground Penetrating Radar, 2nd ed. London, U.K., Institution of Engineering and Technology.

[2] Annan, A. P., (2005), Ground Penetrating Radar,  in Investigations in Geophysics, Society of Exploration Geophysicists, pp. 357-438.

[3] Taflove, A., Hagness, S. C., (2005), Computational electromagnetic: The Finite-Difference Time-Domain Method, Artech House, Norwood.

[4] Warren, C., & Giannopoulos, A., (2011), Creating Finite-Difference Time-Domain Models of Commercial Ground Penetrating Radar Antenna Using Taguchi’s Optimization Method, Geophysics, 76(2), G37-G47.

[5] Zadhoush, H., Giannopoulos, A., Giannakis, I., (2020), Optimising GPR time-zero adjustment and two-way travel time wavelet measurement using a realistic 3D numerical model, Near Surface Geophysics, Under review (Minor revisions).

[6] Zadhoush, H., (2020), Numerical Modelling of Ground Penetrating Radar for Optimization of the Time-zero Adjustment and Complex Refractive Index Model, PhD Thesis Submitted at The University of Edinburgh.
Short Review of True-North Alignment Method on the Field Demonstrating the benefits of the use of an Optical Gyrocompass
Authors: Guattari Frédéric , Auregan Pierrick , de Toldi Elliot , Laudat Theo , Mattio Laurent
Published: March 2021

To install a seismometer with a properly defined orientation - inside a vault or into a borehole - as a single station including various instruments or as a part of an array - an ‘adequate’ tool and an ‘absolute’ reference are needed.

In the past, and sometimes it persists nowadays, magnetic North have been used as a reference for Z-orientation of seismic station. Several studies have extensively measured the orientation error that have been made with this method, using an optical gyrocompass providing True-North as a reference, and their work will be summarized here.

In these studies, optical Gyrocompass is said to be the good solution, even if it is too heavy, expensive, and difficult to export. This paper will explain how iXblue has overcome these limitations to design the new-born Seistans Optical Gyrocompass.

Moreover, to aim True-North with a reliable accuracy is not the only think you need to do on the field. The method to transfer the North-line from the gyrocompass to the instrument to aligned must not induce errors that ruined the accuracy obtained using state-of-the-art gyrocompass. So an exhaustive study of the different ways to transfer the orientation from the compass to the aligned sensor will be presented, and corresponding added uncertainty will be evaluated, which is a good way to promote good practice on the field.

Finally, some figures will be gathered and shared from literature to quantify the precision needed for the alignment of a seismic sensor. There are today so few papers about this important matter that it is worth to spread their information.
Multiscale modelling of a (semi-)urbanised catchment with the help of the Multi-Hydro model
Authors: Ribeiro-de-Moura Rodrigo
Published: March 2021

The fully distributed and scalable model Multi-Hydro (MH) enables a high resolution hydro-dynamic modelling of surface flow, infiltration, sewer flow and their interactions, including the retroaction of sewer overflows on surface. Its modular structure simplifies the introduction of new numerical engines, e.g., to simulate air quality or microclimate, to test implementation methodologies and/or develop user-friendly tools for urban management and design, going well beyond the flood control purposes.

Several extensions of MH were recently developed and greatly widened its functionalities. To give an example, they could be used for modelling and visualisation of climatic stress in the built environment and the resulting outdoor comfort, with an identification of cool corridors and climate safe paths.

By considering the high-resolution distributed rainfall, but also the layout of impervious and green areas on a range of representative streetscapes of a (semi-)urbanised catchment, this presentation addresses the questions on efficiency of additional ecosystem performances related to water availability (as cooling effect). Several scenarios were considered regarding possible adaption strategies, with a particular emphasis on  a multiscale analysis of :

the confrontation between models and experimental data;

the model induced structural choices and resulting limitations, in particular on the relevant space-time scales, as well their capacity to represent the extreme heterogeneity of the fields;

the modelling of environmental variability across scales rather than at a given scale.
Microaggregate in soil: Current concepts, topics, and challenges in a nutshell
Authors: Totsche Kai Uwe , Kögel-Knabner Ingrid ,   MADSoil Research Consortium
Published: March 2021

Microaggregate development and turnover and its linkage to the function of soils is a major research field in soil science. Microaggregates are deemed the most stable and persistent compound structures in soils and are conceptually considered as the fundamental structural building units of a – frequently even hierarchically structured – soil (Totsche et al. 2018). Most of the research on microaggregates has been motivated by the search for a better understanding of the storage and dynamics of soil organic matter. Fueled by the advent of instrumental analytical tools that allow to study soil structural and chemical heterogeneity, biodiversity and biogeography on the submicron scale, and expedited by the advancement of theoretical approaches for joint reconstruction and interpretation in-silico  recent direction changed: New foci are the formation, stability and turnover of microaggregates, their composite building units, the patterns of spatial allocation of the various inorganic, organic and biotic materials involved, and the role microaggregates might have in and for the functioning of soil. This presentation will give a compact overview on the current topics, challenges and concepts in microaggregate research and the role of microaggregates for the architecture, properties and functions of soils.
Methane in frozen and thawed soils of the western sector of Russian Arctic
Authors: Zadorozhnaia Nataliia , Oblogov Gleb , Vasiliev Alexander , Streletskaya Irina
Published: March 2021

Many researchers study the Earth's climate change and the impact of the greenhouse effect on this process. The large amount of methane (CH4) is preserved in permafrost. In this regard, scientists recently pay a great attention to the problem of methane emission during the permafrost degradation in the Arctic zone. Until now, the methane content in underground ice, frozen Quaternary sediments has been studied insufficiently. The methane content in the active layer is especially poorly studied.

The authors researched methane content in frozen grounds of the upper permafrost horizon (transition zone) and in thawed sediments of the active layer for different tundra landscapes near the Marre-Sale polar station on the western coast of the Yamal peninsula and for landscapes of the Pechora river estuary area (Russia).

More than 420 samples of gas from sediments in active and transient layer were collected in Marre-Sale and 36 samples in Pechora area. To determine the methane content, the samples were placed in syringes and degassed using the “head space” technique. CH4 measurements were carried out on a chromatograph with flame ionization detector (FID) Shimadzu GC-2014 (Japan) in the laboratory of Federal State Institution “VNIIOkeangeologiya” (Saint-Petersburg, Russia).

Methane content in the frozen and thawed sediments of different dominant landscapes of typical tundra on Yamal peninsula and landscapes of southern tundra on Pechora area is extremely variable. The greatest amount of methane is typical for the most wet landscapes with primarily of silt loam soils. In dry primarily sandy well-drained landscapes, the methane content is low. The highest methane content is measured within the low floodplain of river, water tracks, swampy depressions of polygonal relief, and lake basins landscapes (mean varied from 0.8 to 2.5 ml [CH4] / kg, with a maximum of 9.0 ml [CH4] / kg). For landscapes of the moist surface of typical tundra, the average values of methane content were approximately 0.4 ml [CH4] / kg (with a maximum of 3.4 ml [CH4] / kg). The lowest methane contents in soils were characteristic of the landscapes of well-drained tundra, and sand fields where the average values do not exceed 0.2 ml [CH4] / kg. Mean methane content in soils of Pechora river mouth landscapes varied from 0.05 to 4.5 ml [CH4] / kg, with a maximum of 15.8 ml [CH4] / kg.

Determined that methane contents in the frozen soils of the transition zone is 2 to 5 times higher than in the soils of the active layer. High content of methane in upper layers of permafrost should be considered as a significant source of methane, which can be involved in emission of greenhouse gases into the atmosphere during permafrost degradation.
Distorsion of Croatian national positional reference system CROPOS after the earthquake M6.2 in NW Croatia
Authors: Bjelotomić Oršulić Olga , Varga Matej , Bašić Tomislav , Korbar Tvrtko
Published: March 2021

The precision of geodetic measurements is reliable as much as the reference on which the measurements relies on. From the aspect of todays' most used geodetic method, the GNSS measurements, its reference is defined through a national reference frame established with corresponding reference stations. Hazardous earthquake of M=6.2 occurred in NW Croatia at the very end of year 2020. Earthquake was one of the most hazardous natural phenomena in Croatia in the last century. Due to the tremendous damages left behind, in which also one of the national GNSS reference station temporarily out of the service, we analyzed how much earthquake had impacted the surrounding reference stations and overall the Croatian national reference frame CROPOS. The presentation shows the analysis of GNSS time series in order to determine the scale of displacement of the CROPOS CORS GNSS reference stations due to the earthquake. The results show the greatest shift of 5 cm east on Sisak reference station, with stations in circumstances of 100 km impacted by the earthquake and shifted between 1 and 2.5 cm positional and 2-4 cm in height. Identified displacement of national reference frame and the ground displacement over the affected area will have domino effect on the geodetic field measurements and cadastral survey on that area.
Seismic observations of the 2021 Uttarakhand landslide/debris flow and flood events
Authors: Pilz Marco , Cotton Fabrice , Cook Kristen , Dieze Michael , Hovius Niels , Rekapalli Rajesh , Vempati Venkatesh , Singh Ravi Prakash , Rao N. Purnachandra , Srinagesh Davuluri , Tiwari Virendra M.
Published: March 2021

Debris flows and corresponding floods are a significant natural hazard for downstream communities in vulnerable regions, as yet unpredictable triggers and remote source locations might cause dynamics which are difficult to measure and quantify. Continuous observational coverage offered by seismic monitoring is one potential avenue for addressing this problem. Displacement of mass at Earth’s surface generates elastic seismic waves, which carry information about the temporal and spatial variability of the source and which can be recorded by seismometers at high temporal resolution across large spatial scales. Here, we report on seismic observations of the destructive 2021 Uttarakhand (India) debris flow and flood events. By means of a dense regional seismic network, we track and quantify the spatial and temporal evolution of the flood. Using continuous time-stamped seismic observations, a coherent signal of the flood movement is observed in a limited frequency band which can be tracked down the valley during the flood duration. Our analysis highlights potential benefits of using a network-wide seismic monitoring systems.
Snow as environmentally low-impact sampling media for mineral exploration - a case study from Northern Finland
Authors: Pospiech Solveig , Taivalkoski Anne , Lahaye Yann , Sarala Pertti , Kinnunen Janne , Middleton Maarit
Published: March 2021

Modern mineral exploration is required to be conducted in a sustainable, environmentally friendly and socially acceptable way. Especially for the geochemical exploration on ecologically sensitive areas this poses a challenge because any heavy machinery or invasive methods might cause long-lasting damage to nature. One way of reducing the impact of mineral exploration on the environment during the early stages of exploration is to use surface sampling media, such as upper soil horizons, water, plants and, on high latitudes, also snow. Of these options, snow has several advantages: Sampling and analysing snow is fast and low in costs, it has no impact on the environment, and in wintertime it is ubiquitous and available independent of the ecosystem.
In the “New Exploration Technologies (NEXT)” project*, snow samples were collected in March-April 2019 to evaluate the usage of snow as a sampling material for mineral exploration. The test site was the Rajapalot Au-Co prospect in northern Finland, located 60 km west from Rovaniemi and operated by Mawson Oy. A stratified random sampling strategy was applied to place the sampling stations on the test site. The sampling comprised 94 snow samples and 12 field replicates. The samples were analysed at the GTK Research laboratory using a Nu AttoM single collector inductively coupled plasma mass spectrometry (SC-ICPMS) which returned analytical results for 52 elements at the ppt level. After applying quality control to the data, the elements Ba, Ca, Cd, Cr, Cs, Ga, Li, Mg, Rb, Sr, Tl and V showed good quality and were used in the final data analysis.
Geochemical data of drill cores were used to train a model to predict bedrock geochemistry based on the 12 available element concentrations of snow analysis. Prior to statistical methods, all geochemical data was transformed to log-ratio scores in order to ensure that results are independent of the selection of elements and to avoid spurious correlations (compositional data approach). Results show that snow data provide reasonable predictions of bedrock geochemistry for elements such as Ca, Cr, Li and Mg, but also for elements not used in snow data, such as Mn and Na. This suggests that snow can serve as a lithogeochemical mapping tool for potential geological domains. For the ore related elements Au, Ag, Co, and U the model provided predictions with higher uncertainty. Yet, the pattern of the predicted values of ore related elements show that snow can also be used to delineate prospective areas for continuing exploration with more sensitive methods.
*) This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 776804.
Geophysical and geomatic recent surveys at Whymper hanging Glacier (Aosta Valley – Italy)
Authors: Troilo Fabrizio , Gottardelli Simone , Giordan Daniele , Dematteis Niccolò , Godio Alberto , Vincent Christian
Published: March 2021

The Grandes Jorasses Massif culminates at 4203m at the Punta Walker summit on the border between France and Italy. The south slope of Grandes Jorasses is widely glaciated and overlies a populated and highly frequented area, the Val Ferret, presenting the main infrastructure being the road in the valley bottom and different hamlets the most important being Planpincieux village. Located at an altitude between 3900 and 4100 m, the Whymper Serac is a hanging glacier that undergoes periodic gravity-driven instabilities. On 1st June of 1998, 150.000m3 of ice fell, and the resulting ice avalanche reached 1750m, at a mere 400m from houses of the Le Pont village and the main Road. The monitoring activity started in 1997: a  series of boreholes had been drilled to assess the basal thermal regime of the Serac and subsequently install a monitoring system for failure prediction time. Since then, no other thermal investigation was repeated.

In September 2020, three thermistor chains in three different boreholes were installed by means of hot water diesel-powered drill machine on Whymper Serac. Geophysical and topographic reconstructions at Whymper Serac are crucial for the volume estimation of possible instabilities; therefore, to assess ice thickness changes and morphological modifications, different geophysical soundings and topographical surveys were performed in 2020. The ice thicknesses were estimated employing a first airborne GPR survey on the 4th of July 2020 using a pair of orthogonal 25 MHz antennas; a second airborne GPR survey was performed using a single 40 MHz antenna on 14/12/2020. Moreover, an in-situ measure was performed through passive seismic sounding later processed as HVSR analysis to assess ice thickness estimation.

The geomatic analysis was performed by aero photogrammetric UAV surveys, and additional GCPs were materialized. The first assessment of thermal regime variation on the Serac suggests that risk scenarios, as well as monitoring possibilities, are rapidly evolving. According to these findings, bigger volumes could be involved in the destabilization of the Serac, and the evolution of the Serac from cold-based to polythermal poses a big challenge in the monitoring of deformations for the possibility of time prediction of failures. Therefore, experimentation of a long-range GB-InSAR surface deformations measures has begun to implement the existing monitoring network based on a robotized total station with reflective prisms used on the Serac. The installation of more thermistor chains is planned for summer 2021, to validate the previous results. Ground-based GPR soundings and more HVSR seismic measurements have as well been planned for 2021 for the more robust reconstruction of the bedrock geometry.
Measurable impact of river incision on rift tectonics
Authors: Olive Jean-Arthur , Malatesta Luca , Behn Mark , Buck Roger
Published: March 2021

Models that couple tectonics and surface processes commonly predict that efficient erosion and sedimentation help focus crustal deformation onto fewer, longer-lived faults. However, because their geomorphic parameters are difficult to calibrate against real landscapes, the sensitivity of tectonic deformation to a realistic range of surface process efficiencies remains poorly known. Here we model the growth of structurally simple half-graben structures subjected to fluvial incision of specified efficiency and sedimentation. Numerical simulations predict that infinitely-efficient erosion and deposition (i.e., complete surface leveling) can more than double the maximum offset reached on a master normal fault before crustal strain localizes elsewhere. Further, leveling footwall relief tends to promote the migration of strain towards the hanging wall to form new grabens instead of horsts. 

         To test whether the efficiency of river incision can vary sufficiently across real rifts to exert a control on tectonic styles, we analyze the profiles of rivers draining half-graben footwalls and horst blocks in the Basin & Range, Taupo, Rio Grande, and East African Rift. We adapt the standard methodology of equilibrium river profile analysis to account for spatial variations in uplift expected from crustal flexure in a fault-bounded block. Erosional efficiency (EE) is defined as the inverse of the (dimensionless) slope of uplift- and drainage area-corrected river elevation plots.  Measured EEs range between ~0.1 and ~4, reflecting natural variability in lithology, climate, and uplift rates across sites. Incorporating EEs within this documented range in numerical simulations, we find that increasing EE can increase the maximum throw on half-graben master faults by ~50%. Changing EE also affects the geometry of subsequent faults, with lower EEs favoring the transition from half-graben to horsts. These models predict that rifting in a colder, stronger continental crust is less sensitive to surface processes and requires even lower EE to develop horst structures. Our simulations are consistent with a compilation of EE, crustal strength proxies, and fault characteristics across real rift zones. These results suggest that natural variability in climatic conditions and surface erodibility has a measurable impact on the tectonic makeup of Earth's plate boundaries.
Microbial inputs at the litter layer translate climate into altered organic matter properties
Authors: Kohl Lukas , Myers-Pigg Allison , Edwards Kate A. , Billings Sharon A. , Warren Jamie , Podrebarac Frances A. , Ziegler Susan A.
Published: March 2021

Plant litter chemistry is altered during decomposition but it remains unknown if these alterations, and thus the composition of residual litter, will change in response to climate. Selective microbial mineralization of litter components and the accumulation of microbial necromass can drive litter compositional change, but the extent to which these mechanisms respond to climate remains poorly understood. We addressed this knowledge gap by studying needle litter decomposition along a boreal forest climate transect. Specifically, we investigated how the composition and/or metabolism of the decomposer community varies with climate, and if that variation is associated with distinct modifications of litter chemistry during decomposition. We analyzed the composition of microbial phospholipid fatty acids (PLFAs) in the litter layer and measured natural abundance δ13CPLFA values as an integrated measure of microbial metabolisms. Changes in litter chemistry and δ13C values were measured in litterbag experiments conducted at each transect site. A warmer climate was associated with higher litter nitrogen concentrations as well as altered microbial community structure (lower fungi:bacteria ratios) and microbial metabolism (higher δ13CPLFA). Litter in warmer transect regions accumulated less aliphatic‐C (lipids, waxes) and retained more O‐alkyl‐C (carbohydrates), consistent with enhanced 13C‐enrichment in residual litter, than in colder regions. These results suggest that chemical changes during litter decomposition will change with climate, driven primarily by indirect climate effects (e.g., greater nitrogen availability and decreased fungi:bacteria ratios) rather than direct temperature effects. A positive correlation between microbial biomass δ13C values and 13C‐enrichment during decomposition suggests that change in litter chemistry is driven more by distinct microbial necromass inputs than differences in the selective removal of litter components. Our study highlights the role that microbial inputs during early litter decomposition can play in shaping surface litter contribution to soil organic matter as it responds to climate warming effects such as greater nitrogen availability.
Reconstruction of the entire rift architecture of Theistareykir Fissure Swarm (northeast Iceland): integration between extensive UAV and field surveys
Authors: Russo Elena , Corti Noemi , Bonali Fabio Luca , Tibaldi Alessandro , Pasquaré Mariotto Federico , Fallati Luca , Marchese Fabio
Published: March 2021

Reconstructing the origin and kinematics of structures along active rifts is essential to gain a deeper knowledge on rifting processes, with important implications for the assessment of volcanic and seismic hazard. Here we reconstruct the architecture of an entire rift, the 70-km-long Theistareykir Fissure Swarm (ThFS) within the Northern Volcanic Zone of Iceland, through the collection of an extensive amount of 7500 quantitative measurements along extension fractures and normal faults, thanks to the integration between Unmanned Aerial Vehicles (UAV) mapping with centimetric resolution through Structure from Motion (SfM) techniques and extensive field surveys with classical methods. Quantitative measurements, collected across a wide area during several campaigns, comprise strike, opening direction and amount of opening at extension fractures, and strike and offset values at faults, along 6124 post-Late Glacial Maximum (LGM) and 685 pre-LGM structures.

The extent of the area covered by our data allowed us to pinpoint differences in the structural architecture of the rift. From south to north: i) extension fractures and faults strike ranges from mainly N10°-20°, to N00-10°, to N30-40°; ii) the opening direction starts from N110°, reaches N90-100° in the center and amounts to N125° in the northernmost sector; and iii) the dilation amount is in the range 0.1–10 m, then 0.1–9 m and it finally reaches 0.1–8 m. We explore such differences as due to the interaction with the WNW-ESE-striking Husavik-Flatey transform fault and the Grímsey Oblique Rift (Grímsey lineament), and to the structural inheritance of older NNE- to NE-striking normal faults. The reconstruction of the stress field resulting from such data allows the interpolation of the σhmin values, through the unpublished software ATMO-STRESS, prepared in the framework of the EU NEANIAS project, in order to plot and examine the strain field.

Furthermore, mechanisms of rift propagation and the relation between magma systems are here investigated through the analysis of 281 slip profiles of the main Pleistocene-Holocene faults. Our data show a mechanism of along-axis propagation of the rift outward from the volcano: in fact, north of the volcano, 75% of the asymmetric faults propagated northward, whereas south of the volcano 47% of the asymmetric faults propagated southward. This can be due to the combination between the development of faults following lateral dyke propagation outward from the magma chamber, and faults nucleation near the volcano as a consequence of the different crustal rock rheology produced by a higher heat flux.