bluuebunny/crossref_metadata_2025 huggingface dataset:
Late Holocene thermohaline perturbation of the N-Atlantic Subpolar Gyre linked to exceptional Greenland Ice Sheet melting between 4.4 and 4.0 ka BP
Authors: Kuijpers Antoon , Seidenkrantz Marit-Solveig , Schneider Ralph , S. Andresen Camilla , Hygom Jacobsen Signe , Oksman Mimmi , C. Orme Lisa , Ren Jian , Solignac Sandrine
Published: March 2020

Knowledge of the impact of past climate warming on Greenland Ice Sheet stability is an important issue for assessing  thresholds that are critical for a potential ice sheet collapse. For the late Holocene, evidence has recently been found of a so-called 4.2 ka BP event(1) including a prominent warming spike in several ice core records from Greenland and Canada (Agassiz).  Also lake records from both Northwest(2) and South Greenland(3) support pronounced summer warming during that time. After c. 4.0 ka BP NW Greenland July air temperature dropped by about 3o C. Coeval with this exceptional atmospheric warming anomaly over northern Canada and parts of Greenland, abrupt cooling and freshening affected  the N-Atlantic subpolar gyre where Labrador Sea deep convection ceased(4). Northern N-Atlantic climate generally deteriorated. With our contribution we present Holocene sub-bottom profiling  and sedimentary shelf and  fjord records from Southwest Greenland and Disko Bay that indicate exceptional Greenland Ice Sheet melting 4.4-4.0 ka BP at a rate and magnitude not recorded since early Holocene deglaciation. Extremely strong melt water discharge resulted in erosion of fjord sediments(5) and local deposition of up to several meters thick meltwater sediment on the shelf(6-8).  Timing of this melting event corresponds to a significant anomaly in hydrographic parameters of the Labrador Current off Newfoundland(9,10), which is concluded to have resulted in thermohaline perturbation of the N-Atlantic Subpolar gyre.   

(1) Weiss, H. 2019. Clim Past doi:10.5194/cp-2018-162-RC2

(2) McFarlin, J.M. et al. 2018. PNAS doi:10.1073/pnas.1720420115

(3) Andresen, C.S. et al. 2004. J Quat Sci 19(8) doi:10.1002/jqs.886

(4) Klus, A. et al. 2018. Clim Past doi:10.5194/cp-14-1165-2018

(5) Ren, J. et al. 2009. Mar Micropal doi:10.1016/j.marmicro.2008.12.003

(6) Hygom Jacobsen, S. 2019. Master Thesis Aarhus Univ, Dept. of Geoscience, pp105

(7) Schneider, R. 2015. Cruise Rep epic.awi.de/id/eprint/37062/131/msm-44-46-expeditionsheft.pdf

(8) Kuijpers, A. et al. 2001. Geol. Greenland Surv Bull 189, 41-47

(9) Solignac, S. et al. 2011. The Holocene, doi: 10.1177/0959683610385720

(10) Orme, L. et al 2019. The Holocene (submitted)
An Observational Study of Macroscopic and Microphysical Characteristics of Clouds and Precipitation on Mount Lu, Jiangxi, China
Authors: Guo Lijun , Guo Xueliang , Lou Xiaofeng , Lu Guangxian , Lyu Kai , Sun Hemin , Li Jun , Zhang Xiaopeng
Published: March 2020

The Mount Lu (Lushan) observational station of cloud and fog in Jiujiang, China was restarted in 2015. The observational experiment of clouds/fog and precipitation was conducted from 2015 to 2018 in Mount Lu station. The observation dataset of clouds/fog on the Mount Lu were collected and established. The observational characteristics of clouds and precipitation were investigated from November 2015 to February 2018, including microphysics properties of clouds/fog and precipitation of 15 months in cold and warm seasons. The statistical results suggested that the heavy precipitation on the Mount Lu was frequent in summer with the maximal daily precipitation exceeding 100 mm. The maximal number of clouds and fogs days reached 25 days per month, with the lowest visibility about 20m. Due to radiative effect of clouds and fog in the (early) morning, the lowest temperature in the diurnal variation of temperature happened at about 9 o’clock, right before the dissipation of clouds and fog. Based on the analysis of radar data, stratiform precipitation, stratocumulus and convective precipitation in the autumn and winter respectively accounted for 29%, 44% and 27% of the total precipitation, and convective and stratocumulus precipitation in the spring and summer respectively accounted for 83% and 17% of the total precipitation. Compared with precipitation in urban areas, the small and medium raindrops were predominant in the precipitation processes on Mount Lu. Compared with fog in urban areas, the clouds and fog were characterized by smaller number concentration, the more significant bimodal and wider spectra. With the increase of precipitation within cloud, the more raindrops in number and larger raindrops in size were easier to initiate the coagulation mechanism, resulting in reduction of cloud droplets smaller than 11μm and larger than 30 μm. As a result, the peak at 11μm became more obvious. During the snowfall periods, the small cloud droplets were abundant, and the solid precipitation growth consumed large freezing cloud droplets through the rimming process.
Preferential fluid flow and chemical transport in saturated fractured porous media and in heterogeneous vadose zones: Two sides of the same coin
Authors: Berkowitz Brian
Published: March 2020

Preferential fluid flow and chemical transport occur on scales ranging from pores to aquifers and catchments, in both fully and partially water-saturated geological formations. Preferential flows can be considered, in a general sense, manifestations of self-organization that hinders perfect mixing within a system, and leads to faster throughput of water and chemicals. However, unified concepts for the onset, spatiotemporal patterning, and magnitude of such preferential flows are generally difficult to define; and this is compounded by the difficulty – or practical impossibility – of obtaining detailed measurements of the structure and hydraulic functioning of vadose zones, catchments, and aquifers. We propose that conceptualizations and quantitative characterizations of preferential fluid flow and chemical transport in all of these systems can be unified in terms of tools that connect them in a dynamic framework. Here, we discuss key, shared features of fluid flow and chemical transport dynamics in each of these two systems, based on both laboratory and field measurements, and numerical simulations. We show how even well-connected fracture networks can display highly non-uniform preferential paths for fluid and chemicals. We then recognize that this behavior is similar to that of rapid infiltration in soils and the vadose zone, which exhibits strongly localized preferential pathways in root channels, cracks, worm burrows or connected inter-aggregate pore networks. Moreover, both types of domains can display “memory effects”, in terms of the location and functioning of preferential paths even during perturbations in the velocity gradient and/or rates of infiltration. We argue that the ubiquity of unresolved (or uncharacterized) heterogeneity at all spatial and temporal scales necessitates the use of effective medium models that enable an accounting of a wide range of flow and transport behaviors. For chemical transport, we focus on a probabilistic modelling framework that can capture the dynamics in heterogeneous vadose zones and fractured (or otherwise heterogeneous) geological formations. We then demonstrate application of this model to interpret field-scale tracer breakthrough curves (concentration vs. time) in a highly fractured karst formation over length scales of up to more than 7 km.
Multidecadal trend analysis of aerosol radiative properties at a global scale
Authors: Collaud Coen Martine , Andrews Elisabeth , Lund Myhre Cathrine , Hand Jenny , Pandolfi Marco , Laj Paolo ,   SARGAN: trend analysis of aerosol radiative properties
Published: March 2020

In order to assess the global evolution of aerosol parameters affecting climate change, a long-term trend analyses of aerosol optical properties were performed on time series from 52 stations situated across five continents. The time series of measured scattering, backscattering and absorption coefficients as well as the derived single scattering albedo, backscattering fraction, scattering and absorption Ångström exponents covered at least 10 years and up to 40 years for some stations. The non-parametric seasonal Mann-Kendall (MK) statistical test associated with several prewhitening methods and with the Sen’s slope were used as main trend analysis methods. Comparisons with General Least Mean Square associated with Autoregressive Bootstrap (GLS/ARB) and with standard Least Mean Square analysis (LMS) enabled confirmation of the detected MK statistically significant trends and the assessment of advantages and limitations of each method. Currently, scattering and backscattering coefficients trends are mostly decreasing in Europe and North America and are not statistically significant in Asia, while polar stations exhibit a mix of increasing and decreasing trends. A few increasing trends are also found at some stations in North America and Australia. Absorption coefficients time series also exhibit primarily decreasing trends. For single scattering albedo, 52% of the sites exhibit statistically significant positive trends, mostly in Asia, Eastern/Northern Europe and Arctic, 18% of sites exhibit statistically significant negative trends, mostly in central Europe and central North America, while the remaining 30% of sites have trends, which are not statistically significant. In addition to evaluating trends for the overall time series, the evolution of the trends in sequential 10 year segments was also analyzed. For scattering and backscattering, statistically significant increasing 10 year trends are primarily found for earlier periods (10 year trends ending in 2010-2015) for polar stations and Mauna Loa. For most of the stations, the present-day statistically significant decreasing 10 year trends of the single scattering albedo were preceded by not statistically significant and statistically significant increasing 10 year trends. The effect of air pollution abatement policies in continental North America is very obvious in the 10 year trends of the scattering coefficient – there is a shift to statistically significant negative trends in 2010-2011 for all stations in the eastern and central US. This long-term trend analysis of aerosol radiative properties with a broad spatial coverage enables a better global view of potential aerosol effects on climate changes.
Regional Mean Sea Surface Model over the Eastern Mediterranean Sea
Authors: Murshan Milaa , Devaraju Balaji , Balasubramanium Nagarajan , Dikshit Onkar
Published: March 2020

The Mean Sea Level is not an equipotential surface because it is subject to several variations, e.g., the tides, currents, winds, etc. Mean Sea Level can be measured either by tide gauges near to coastlines relative to local datum or by satellite altimeter above the reference ellipsoid. From this observable quantity, one can derive a non-observable quantity at which the potential is constant called geoid and differs from mean sea surface by amount of ±1 m. This separation is called Sea Surface Topography. In this research, the data of nine altimetric Exact Repeat Missions (Envisat, ERS_1 of 35 days (phase C and G), ERS_2, GFO, Jason_1, Jason_2, Jason_3, Topex/Poseidon and SARAL) were used for computing the regional mean sea surface model over the eastern Mediterranean Sea. The data of all missions together span approximately 25 years from September -1992 to January-2017 and referenced to Topex ellipsoid.  Which is later transformed to WGS84 ellipsoid, as it is chosen to be a unified datum in this study. Prior to computing the altimetric MSS,  altimetric sea surface height measurements were validated  by comparing  time series of altimetric-MSL with mean sea level time series calculated from three in-situ tide gauge measurements.  The sea surface heights values of the derived MSS model is between 15.6 and 26.7 m. And the linear trend slope is between -3.02 to 6.53 mm/year.

Keywords: Mean Sea Level, Satellite Altimetry, Tide Gauge, Exact Repeat Missions
Earthquake crisis unveils the growth of an incipient continental fault system
Authors: Gràcia Eulàlia , Grevemeyer Ingo , Bartolomé Rafael , Perea Héctor , Martínez-Loriente Sara , Gómez de la Peña Laura , Villaseñor Antonio , Klinger Yann , Lo Iacono Claudio , Diez Susana , Calahorrano Alcinoe , Camafort Miquel , Costa Sergio , d'Acremont Elia , Rabaute Alain , Ranero César R.
Published: March 2020

Large continental faults extend for thousands of kilometres and often form the tectonic boundaries between plates that are associated with prominent topographic features. In these active areas, well-defined faults produce large earthquakes, and thus imply a high seismic hazard. These paradigms are called into question in the Alboran Sea, which hosts an allegedly complex diffuse boundary between the Eurasia and Nubia plates, and we discovered one of the few examples worldwide of the initial stages of these key tectonic structures. On the 25th January 2016, a magnitude Mw6.4 submarine earthquake struck the north of the Moroccan coast, the largest event ever recorded in the Alboran Sea. The quake was preceded by an earthquake of magnitude Mw5.1 and was followed by numerous aftershocks whose locations mainly migrated to the south. The mainshock nucleated at a releasing bend of the poorly known Al-Idrissi Fault System (AIFS). According to slip inversion and aftershock distribution, we assume a rupture length of 18 km. Here we combine newly acquired multi-scale bathymetric and marine seismic reflection data with a resolution comparable to the studies on land, together with seismological data of the 2016 Mw 6.4 earthquake offshore Morocco – the largest event recorded in the area – to unveil the 3D geometry of the AIFS. We found that, despite its subdued relief, the AIFS is a crustal-scale boundary. We report evidence of left-lateral strike-slip displacement, characterize their fault segments and demonstrate that the AIFS is the source of the 2016 events. The occurrence of the Mw 6.4 earthquake and previous events of 1994 and 2004 supports that the AIFS is currently growing through propagation and linkage of its segments, which eventually might generate a greater rupture (up to Mw 7.6), increasing the potential hazard of the structure. The AIFS provides a unique model of the inception and growth of a young plate boundary system in the Alboran Sea (Western Mediterranean).

This work has been recently published in Nature Communications (IF:12.35), 10, 3482 (2019) doi:10.1038/s41467-019-11064-5. I would like to present our article recently published in NCOMM, so, please consider our work for an ORAL INVITED presentation. Many thanks!
Demonstrating change from a drop-in engagement activity through pre- and post- graffiti walls: Thematic analysis and quantitative linguistics applied to a soundscape exhibit
Authors: Archer Martin
Published: March 2020

Evaluation of drop-in engagement activities, particularly trying to demonstrate impact or change, is difficult given their transient nature and many logistical factors. Many typical evaluation techniques such as surveys are often unsuitable and current best practice recommends integrating evaluation methods into the activity itself. We present a novel implementation and analysis of an established evaluation method, which has the ability to demonstrate change even from a drop-in activity.

A space soundscapes exhibit saw young families taken on a journey experiencing the real sounds of near-Earth space recorded by satellites – normally inaudible to humans due to their weakness and extremely low pitch. Grafitti walls were placed at the start and end of this journey where participants were prompted by event staff to reflect on what they think space is like. Thematic analysis of the words and drawings from the two walls showed a change from obvious space-themed bodies and typical misconceptions of the lack of sound in space to much more reflective and reactionary results afterwards. Applying quantitative linguistics shows an evolution of the distribution of words which demonstrates a greater diversity following the experience. Similar techniques have been applied to evaluating children’s language as they age, however, we are unaware of this being applied to public engagement activities before. We therefore propose that these methods may be useful in evaluating other drop-in engagement activities and demonstrating the impact that they had.
Evolution of Flare-accelerated Electrons in the Solar Corona and Chromosphere Revealed by Spatially Resolved Microwave and Hard X-Ray Analysis
Authors: Kuroda Natsuha , Fleishman Gregory , Gary Dale , Nita Gelu , Chen Bin , Yu Sijie
Published: March 2020

Hard X-ray (HXR) and microwave (MW) observations are highly complementary for studying electron acceleration and transport processes in solar flares. In recent years, a new effort has been made in the MW domain using new high-resolution, multifrequency data from The Expanded Owens Valley Solar Array (EOVSA) and a breakthrough numerical modeling infrastructure that enables us to study properties of high-energy electrons in unprecedented cadence and quantitative detail. This study introduces the observation of an M1.2 flare that occurred on 2017 September 9 and analyzes the evolution of the nonthermal electrons in the corona based on EOVSA MW spectral imaging data. We find a significant spectral hardening of the MWemitting nonthermal electron population in the corona, using EOVSA lower-frequency (<7 GHz) observations over a selected 4-minute window of the flare's impulsive phase. We compare this spectral evolution with the evolution of the spectral index of nonthermal electrons emitting in the chromosphere, derived from HXR observations from the Reuven Ramaty High Energy Solar Spectroscopic Imager. We discuss the general picture of the evolution of the nonthermal electron population in this flare by incorporating observations at the two complementary wavelengths. We also make an estimate of the total energy of the nonthermal electrons contained in the observed coronal low-frequency MW source and discuss its temporal evolution.
Development of plant-available water in soil-like substrate derived from urban wastes and processed by earthworm Dendrobaena veneta
Authors: Willaredt Moreen , Ulrich Susanne , Nehls Thomas , van Scheik Loes
Published: March 2020

Topsoil and peat are often taken from intact rural ecosystems to supply the urban demand for fertile soils and soil-like substrates. One way of reducing this exploitation is to recycle suitable urban wastes to produce Technosols and technogenic soil-like sub­strates. In this study we investigate the role earthworms can play in improving the hydraulic properties of such a soil-like substrate.

In a four-month microcosm experiment, the influence of the earthworm species D.veneta on the hy­draulic properties of brick-compost mixture was examined. Of the ten boxes filled with ca. 11 dm³ of ground bricks (0.7 cm³ cm-3) and green waste compost (0.3 cm³ cm-3), five contained earthworms (W-boxes) and the re­maining five were used as controls (C-boxes). The substrate was periodically irrigated and the weight of the boxes and of the drained water was monitored. At the same time, images were taken from the front of the boxes to quantify the activity of the earthworms by image analysis. Before and after the experiment, water retention curves were determined from disturbed samples of the substrate using the simplified evaporation method.

After six weeks, differences between the C- and the W-boxes were evident. Micrographs showed brick-compost aggregates only for the substrates processed by earthworms. The earthworm activity leads to reduced evaporation and an increased water content in the respec­tive microcosms. The effect persists even after disturbing the substrate. The propor­tion of plant-available soil water is about 0.02 cm³ cm-3 higher for the substrate processed by earthworms (0.250 ±0.009 cm³ cm-3) compared to the control (0.230 ±0.008 cm³ cm-3).

This study shows that earthworms are capable of ingesting and processing crushed bricks together with compost. The earthworms produced aggregates which persisted after disturbance and had a positive influence on the water retention capacity of such a soil-like substrate constructed from waste.
Biological weathering by the Devonian trees
Authors: Pawlik Lukasz , Buma Brian , Samonil Pavel , Kvacek Jiri , Galazka Anna , Kohout Petr , Malik Ireneusz
Published: March 2020

We applied the biogeomorphic ecosystem engineers concept to the Devonian Plant Hypotheses. By linking these two ideas we want to explore how recent discoveries on the role of trees in weathering processes could support the explanation of global environmental changes in the Devonian period. The occurrence of first land plants, vascular plants, trees, and complex forest ecosystems likely changed the nature and pace of many geomorphic and pedogenic processes. For instance, intensification of biological weathering driven by vascular plants might have influenced the global climate through consumption and accumulation of a large volume of atmospheric CO2. Innovation in the form and function of trees likely strongly influenced these processes, including soil stabilization via deep root systems. Mycorrhizal relationships further influenced weathering via chemical processes. While the lack of solid evidence in the fossil record still pose a problem, the progress in our understanding of soil-weathering processes induced by trees and root systems has expanded greatly in recent years, especially in terms of their biogeomorphic functions (e.g. tree uprooting, pedoturbations, biomechanical weathering, etc.), and can provide insights and testable hypotheses regarding the role of trees in the Late Devonian.
Modelling Fluid Migration and Seismicity in an Active Volcano: A Case Study of Campi Flegrei Caldera, Southern Italy
Authors: Akande Waheed Gbenga , Gan Quan , Cornwell David G. , De Siena Luca
Published: March 2020

Several observables from geological, geophysical and geochemical studies (e.g., seismic velocities, seismic amplitudes/attenuation, isotopic ratios, and gas composition from fumaroles) have indicated that activities at active volcanoes change over different time scales. We have modelled the cause of this spatiotemporal evolution of deformation and seismicity at Campi Flegrei caldera (southern Italy) as two high coda wave attenuation anomalies (at ~ 1 km and ~2-3 km, respectively) separated by ca 0.5-km-thick low seismic attenuation layer “caprock”, which acts as a major blocking interface for the uprising hot magmatic fluids. We have used these observations along with rock physics data as constraints to conduct fluid flow simulation studies to gain more insights into how this active volcano works. We adopt a coupled modelling approach using mechanical (deformation) and fluid low simulators (TOUGH2-FLAC3D) to simulate seismic slips in the caldera’s computational domain both in isothermal and non-isothermal modes. The method allows us to investigate the roles of both hydromechanical and thermal effects of fluid injections in triggering seismicity at the caldera. The magnitudes of seismicity generated are comparable to the field observations and records of the major seismicity for the caldera in the 1980s.
Pannotia didn’t exist, but the “Pannotian geodynamic cell” formed as the Mozambique Ocean closed and Gondwana amalgamated—the view from Arabia and the East African Orogen
Authors: Collins Alan , Blades Morgan , Foden John , Armistead Sheree , Razakamanana Théodore , Alessio Brandon , Merdith Andrew
Published: March 2020

There is a view that a supercontinent, called Pannotia, existed for a short time at the end of the Neoproterozoic. This hypothetical continent requires collision between Neoproterozoic India, Australia-Mawson and the African and South American continents to occur before formation of Iapetus as Laurentia rifted off Amazonia.

Data from the last decade demonstrate the complexity of consumption of the Mozambique Ocean that separated Neoproterozoic India from the African Neoproterozoic continents (Congo-Tanzania-Bangweulu, the Sahara Metacraton and Kalahari). In particular, the presence of pre-Neoproterozoic terranes that lie within the East African Orogen of Arabia, east Africa, Madagascar and South India demonstrate the multi-phase collision of the this ocean closure?. Here we examine the Cryogenian to Cambrian tectonic geography of the closure of the Mozambique Ocean from a full-plate perspective. We focus on the northern East African Orogen, where Gondwana-formation shortening and crustal thickening has been considerably less than seen in East Africa/Madagascar/South India. We focus on the Neoproterozoic India–Azania–Sahara Metacraton collision represented by the northernmost part of Madagascar (the Bemarivo Domain), and throughout Arabia. We conclude that final ocean closure and formation of central Gondwana occurred in the latest Ediacaran and into the Cambrian, along a suture that passes under the Rub' al Khali region of Arabia and through the northeast of Madagascar. It separates the extended Neoproterozoic India margin (now in Oman, The Seychelles and the northern Bemarivo Domain), from the growing kernel of Gondwana (the east-most parts preserved in Saudi Arabia, Yemen and Central Madagascar).

Considering the early Ediacaran formation of Iapetus, there is growing evidence that Pannotia never existed as connected continental crust, yet the ‘Pannotian geodynamic cell’ with lithosphere divided into continental and oceanic hemispheres had formed. The closure of the Mozambique Ocean represented the termination of >500 million years of subduction at this locale. The termination of this subduction with the formation of Gondwana, and the initiation of the Terra Australis Orogen led to the present geodynamic configuration.
Sub-Ice Sheet Environments in North Victoria Land during the Last Glacial Maximum
Authors: Augustinus Paul C , Frisia Silvia , Borsato Andrea
Published: March 2020

Subglacial calcite precipitates from Boggs Valley (71o55’S; 161o31’E; elevation 1,160 m asl., Northern Victoria Land, Antarctica), provided the first radiometrically-dated petrographic, geochemical and genomic evidence of thermogenic subglacial drainage events linked to subglacial eruptions during the Last Glacial Maximum (LGM). The crusts consist of two fabrics: i) a dirty (particulate-rich) microsparite, which marks catastrophic subglacial discharges of meltwater and a ii) dark columnar calcite that formed in pockets of basal melt. Synchrotron Radiation-based micro X-Ray fluorescence reveal that the dirty microsparite is S-rich, and embeds particulates characterized by high Manganese (Mn), Yttrium (Y) and Iron (Fe) concentrations. From previous work, we also know that the microsparite layers contain organic compounds, including amino acids, from which we extracted DNA fragments of microorganisms that lived in diverse sub-Antarctic environments (Frisia et al., 2017). The elongated columnar calcites are characterized by the presence of Arsenic (As) associated with low concentrations of  Mn. Both elements suggest local anaerobic, chemolitothrophic metabolism. Columnar calcite becomes increasingly rich in S near the “discharge” layers.  

Our preliminary interpretation is that during the LGM subglacial volcanism was crucial to sustain life in sub-ice sheet refugia by injecting both nutrients and diverse microbes into the basal ecosystem. The otherwise nutrient-poor, anoxic subglacial environment sustained a population of chemolithotrophs, which may have also been “allochthonous”.   
The State-of-play of geochronology and provenance in the Neoproterozoic Adelaide Rift Complex
Authors: Lloyd Jarred , Blades Morgan , Counts John , Collins Alan , Amos Kathryn , Hall James , Hore Stephen , Wade Benjamin , Job Ashleigh , Shahin Sameh , Drabsch Matthew
Published: March 2020

The Adelaide Rift Complex is a large sedimentary superbasin in South Australia that formed resultant of Rodinia’s breakup and subsequent evolution of the Australian passive margin of the Pacific basin. It holds a globally significant and exceptionally well-preserved Neoproterozoic–early Cambrian succession. Much work has been done over the last century describing the lithostratigraphy and sedimentology of this vast basin. The rift complex contains evidence for major changes in Earth’s systems, yet, the rocks are poorly dated, and the sediment provenance, and link with tectonic evolution, is remarkably poorly known.

This work provides a centralised database of the currently available, and previously unpublished, detrital zircon geochronology for the Neoproterozoic of the Adelaide Rift Complex, highlighting where the available data is from, and the stratigraphic and spatial gaps in our knowledge. By subjecting the U–Pb detrital zircon data to data analytical techniques, we provide a first look overview of the change in provenance, and subsequently (generalised) palaeo-tectonogeography that this suggests during the Neoproterozoic. These data show a change from dominantly local sources in the middle Tonian, to dominantly far-field sources as the rift-basin develops over time. The Cryogenian icesheets punctuate this with an ephemeral return to more local sources from nearby rift shoulders. This effect is particularly apparent during the Sturtian Glaciation than in the younger Marinoan Glaciation. In the Ediacaran, we see an increasingly stronger influence of younger (<700 Ma) detrital zircons from an enigmatic source that we interpret to be from southern (i.e. Antarctic) sources. We also note that we see a slight shift in the late Mesoproterozoic age peaks, from ca. 1170 Ma to ca. 1090 Ma, with a corresponding decrease in older ca. 1600 Ma detritus.

This work forms the basis of continuing work to improve our understanding of the geochronology, provenance and palaeo-tectonogeography of the Adelaide Rift Complex.
Analyzing impacts of seasonality and landscape gradient on event scale nitrate-discharge dynamics based on nested high-frequency monitoring
Authors: Zhang Xiaolin , Yang Xiaoqiang , Jomaa Seifeddine , Rode Michael
Published: March 2020

Strom event-scale analysis provides insights into nitrate transport dynamics at catchment scale. Investigating different hysteretic relationships between nitrate and discharge can disentangle catchment nitrate functioning both spatially and temporally. In this study, we explored seasonality and landscape gradiemt effects on nitrate concentration-discharge (C-Q) hysteresis patterns based on six-year (2012-2017), high-frequency (15 min) data in the Selke catchment (central Germany). The Selke catchment exhibits heterogeneous combinations of meteorological, hydrogeological, and anthropogenic conditions. Three nested gauging stations were built along the main Selke River, capturing discharge and nitrate concentration from the dominant uppermost mixed forest and arable land, middle catchment pure steep forest and lowland arable and urban land areas, respectively. Amongst the 227 storm events that have been detected, anticlockwise and accretion of C-Q relationships accounted for 76.6% and 75.3%, respectively, while the proportions decreased with the increasing areal share of arable land during summer season. Accretion pattern predominated forest areas (e.g., the middle catchment) throughout the whole year suggesting higher nitrate concentration in dominating interflow than baseflow. In contrast, dilution pattern was almost exclusively observed in lowland areas (dominated by arable and urban areas) in dry periods, indicating lower nitrate concentration in quick runoff components like surface runoff. We further investigated the consistency and variability of hysteresis patterns from upstream to downstream based on shared events. Results indicated hysteresis patterns seemed to be consistent at the three stations when discharge was high enough. Moreover, we found that nitrate load contributions from the upper and lower areas changed seasonally, albeit the dominant share of runoff volume from the upper area throughout the whole year. Such a comprehensive analysis (i.e., clockwise vs. anticlockwise, accretion vs. dilution) enables in-deep discussion of the plausible mechanisms of nitrate dynamics under different landscape conditions. We are also aware of limitations of such statistical data analysis, which can likely be tackled by mechanistic modelling at higher temporal resolutions.
Formation and stability of water dispersible biochar colloids in soil-water systems
Authors: Fang Jing
Published: March 2020

Pathways for the physical disintegration of biochar (BC) and the release of water dispersible BC colloids (WDBC) have received much attention due to their unique impacts on carbon loss and contaminant. However, the current understanding of the mechanisms involved in WDBC formation and associated influencing factors is rather limited. This study systematically explored the formation and colloidal stability of WDBC in various solutions. Results showed that the WDBC yield decreased in the order BC400 (400℃)> BC700 (℃)> BC200(200℃) at a solution ionic strength (IS) ≤ 1 mM （NaCl）. With the exception of BC200, increasing IS (0.1–20 mM NaCl) and decreasing pH (3.0–10.0) significantly inhibited WDBC yield. Release and sedimentation dominated the WDBC formation processes with the former being more susceptible to solution chemistry. The test results of 22 soil solutions showed that the yields of WDBC from BC400 were considerable, while the yield of WDBC from BC700 could be neglected. Principal component analysis showed that the yield of WDBC in soil solutions was closely related to the contents of dissolved organic carbon, Fe and Al ions of soil solutions. WDBC had high colloidal stability and could stabilize well in natural surface waters and soil solutions. These findings represent new knowledge regarding the physical decomposition and the fate of BC in the environment.
The mineralogical, microstructural, chemical characteristics of Recently Formed Fulgurite in Kinmen, Taiwan
Authors: Ting-Ju Meng , Li-Wei Kuo , Chien-Chih Chen , Wen-Jeng Huang , Tze-Yuan Chen
Published: March 2020

Lightning is a common high-energy phenomenon. In particular, cloud-to-ground lightning (CG lightning) generates shock wave and electrical discharge on the ground and forms the associated geological evidence including melting and shock lamella on rocks, termed fulgurites. Because lightning strikes on different protolith (cohesive or non-cohesive rocks), Pasek et al. (2012) divided the fulgurites into four types: (I) sand fulgurites, (ii) soil/clay fulgurites, (iii) calcic-soil fulgurites, and (iv) rock fulgurites. Compared with the reported fulgurites derived from non-cohesive rocks, the recognition of rock fulgurites was rare and remains unclear. Here we report the detailed characterization of rock fulgurites formed in a very recent CG lightning event with microanalytical methods including optical microscope, Field-Emission Scanning Electron Microscope (FESEM), Transmission Electron Microscope (TEM), regular and synchrotron X-ray Powder Diffraction (XRD), and Raman spectroscope. We also provide a CG lightning energy dissipation model constrained by the observed current values. The CG lightning event (the current value is ~ 162 kA) took place on granitic gneiss in Kimen county, Taiwan, on May. 7th, 2018. Our results show that the rock fulgurites were characterized with a black-to-brown thin (~10 μm in thickness) glassy crust with some vesicles covering on the host rock. Hydrous sulfates, including jarosites and gypsums, were recognized to locally deposit on fulgurites, likely suggesting the presence of hydrothermal condition in near-surface exposures after the cessation of the CG lightning. Planer deformation features derived from high pressures (up to several GPa) were found in k-feldspar located beneath the glassy crust, suggesting the presence of shock waves also on the surface. In addition, the estimated melting energy for the observed fulgurite (~20 m2 in area with the thickness of 100 μm) is much less than one one-hundredth of the observed CG lightning. It supports the previous studies that documented most of the electrical discharge was dissipated into ground. Our study establishes a reference rock fulgurites data originated from CG lighting on granitic rocks set for future on-site drilling and presents an application of these data for studies of ancient rock fulgurite relicts.
Imaging fine seismic structures of faults with fault-zone trapped waves
Authors: Su Hui , Zhou Yuanze
Published: March 2020

A fault is a low-velocity zone with widely distributed scatterers compared to the surrounding uniform materials because of the highly damaged rocks in its core. When seismic waves travel through faults, they will reflect on boundaries multiply and be trapped in the fault zones which cause the energy redistribution and generate coda waves with complicated characteristics after the direct P- and S- waves. The coda is named fault-zone trapped waves (FZTWs) (Li et al., 1990). The amplitude and duration characteristics of FZTWs (Li et al., 2016) can be used to constrain the geometric features of the fault and the physical parameters of the scatterers, so the fine structure of the fault can be finally obtained. We observed some FZTWs at several Hi-net stations in Japan, which were generated by low magnitude aftershocks following large earthquakes. Relatively strong FZTWs can be recorded by the seismic stations near or on the fault where the events happened. In this study, we simulate the theoretic envelops of FZTWs with radiative transport theory (Sanborn et al., 2017) for possible velocity models with scatterers described with von Karman distribution (Sato et al., 2012). While the theoretical envelops of FZTWs fit the observed ones well,  the fine fault model is determined. The FZTWs from different events before and after the main shock can be used to determine the physical properties of faults and their adjoint area varied in the seismogenic process, then we can deeply understand the fault evolutions before and after earthquakes. The varying properties of faults can provide a new perspective for earthquake preparation and a new reference for earthquake prediction and promotes the development of earthquake prediction.
Li, Y. G., R. D. Catchings, and M. R. Goldman. 2016, Subsurface Fault Damage Zone of the 2014Mw 6.0 South Napa, California, Earthquake Viewed from Fault‐Zone Trapped Waves. Bulletin of the Seismological Society of America, 106, no. 6,2747-2763. doi: 10.1785/0120160039.
Li, Y. G., P. Leary, K. Aki, and P. Malin. 1990, Seismic Trapped Modes in the Oroville and San-Andreas Fault Zones. Science, 249, no. 4970,763-766. doi: 10.1126/science.249.4970.763.
Sanborn, C. J., V. F. Cormier, and M. Fitzpatrick. 2017, Combined Effects of Deterministic and Statistical Structure on High-frequency Regional Seismograms. Geophysical Journal International, 210, no. 2,1143-1159. doi: 10.1093/gji/ggx219.
Sato H., Fehler M.C. 2012, Seismic Wave Propagation and Scattering in the Heterogeneous Earth, 2nd edn, Springer-Verlag.
Analysis of the Czech magnetic anomaly data obtained by ground-based and airborne magnetic surveys
Authors: Hejda Pavel , Čápová Dana , Hudečková Eva , Kolejka Vladimír
Published: March 2020

The modern epoch of ground magnetic surveying activity on the Czech territory was started by the Institute of Geophysics by setting up a fundamental network of the 1st order in 1957-58. It consists of 199 points and was reoccupied in 1976-78 and 1994-96. The anomaly maps were constructed by subtraction of the IGRF model.

Extensive aeromagnetic measurements have been performed from 1959 to 1972 by permalloy probe of Soviet provenience. The accuracy of the instrumentation was about (and often above) 10 nT. The second period of airborne survey started in 1976. Thanks to the deployment of proton precession magnetometer, the accuracy improved to ~ 2 nT. Since 2004 the measurements were carried out by caesium magnetometer. The data were digitized, known anthropogenic anomalies were cleared away and data were transformed to the regular grid with step 250 m. The final data file of magnetic anomalies ΔT, administered by the Czech Geological Survey, represents a substantial contribution to the exploration of ore deposits and to the structure geology in general.

In view of the fact that data file of magnetic anomalies was compiled from data acquired by heterogeneous methods in the course of more than 50 years, our recent study is aimed at looking into the homogeneity of the data by comparison them with ground-based magnetic survey. A simple comparison of the contour maps showed good similarity of the large regional anomalies. For more detailed analysis, the variation of ΔT in the neighbourhood of all points of the fundamental network was inspected and the basic statistic characteristics were computed. Summary results as well as several examples will be presented accordingly as the INSPIRE compliant services and eventually as the user-friendly web map application and made available on the CGS Portal http://mapy.geology.cz/ and on the updated web of the CzechGeo/EPOS consortium www.czechgeo.cz. Incorporating the map into the World Digital Magnetic Anomaly Map (WDMAM – IAGA) is also under consideration. This data will also be interesting for the EPOS.
Seasonal variation in inorganic carbon parameters in the southwestern Yellow Sea
Authors: Seok Minwoo , Mo Ahra , Park Seunghee , Ko Young Ho , Yun Seongtae , Kim Dayoung , Kim Tae-Wook
Published: March 2020

To better understand carbon cycles in coastal and marginal seas, time-series monitoring is essential because of large temporal variabilities. In this regard, we conducted monthly field researches from April 2017 to May 2019 at the Socheongcho (SCC) Ocean Research Site (37°N‚124°E) in the Yellow Sea located between Korea and China. At each survey, we collected surface seawater samples during approximately 7 days with an sampling interval of two hours (except for spring 2017). Total alkalinity (TA) and dissolved inorganic carbon (DIC) were analyzed by using VINDTA 3C system, Apollo SciTech DIC analyzer and Apollo SciTech Alkalinity Titrator. In addition, a pH sensor (SeapHOx) was installed at the surface layer from September 2018 to June 2019 which is also capable of measuring salinity, temperature and oxygen. Based on the observations, we estimated a partial pressure of carbon dioxide (pCO2) and aragonite saturation state. As expected, seasonal variations in TA and DIC were strongly associated with those of salinity. We also detected a sudden increase DIC in October when vertical mixing was greatly enhanced. Despite a large outgassing during the fall season, annual mean air--sea influx of CO2 was ∼0.61mol·m−2·year−1, suggesting that the study area was a weak sink for atmospheric CO2. Aragonite was enerally reduced during winter (∼1.5). However, no undersaturation event was found during the whole investigation.
Modeling and Data Assimilation of the Ring Current, Relativistic and Ultra-relativistic Electrons in the Inner Magnetosphere
Authors: Shprits Yuri , Aseev Nikita , Drozdov Alexander , Cervantes Villa Juan Sebastian , Castillo Tibocha Angelica Maria , Zhelavskaya Irina , Vasile Ruggero , Effenberger Frederic , Soergel Dominika , Michaelis Ingo , Saikin Anthony
Published: March 2020

Dynamics of energetic and relativistic particles have received a lot of attention in recent years. Significant efforts have been focused on the understanding of the acceleration and loss processes of relativistic electrons and their dynamic evolution, as well as the understanding of ring-current injections in variable magnetic and electric fields. More recently, observations have been used systematically with the aid of data assimilation tools that allow to reconstruct the state of the system by blending models and various observations, and also allow to infer unknown physics and quantify various physical processes. In this study, we present an overview of recent modeling efforts with the VERB-3D and VERB-4D codes. We also show data assimilation from ring current to multi-MeV energies. We present a systematic comparative analysis of the dominant acceleration and loss processes for ring current, relativistic, and ultra-relativistic electrons and compare them. In particular, modeling and data assimilation reveal the missing physical processes at these three ranges of energies. Sensitivity simulations show that the background plasma density, location of the magnetopause, accurate description of electric and magnetic fields, and the description of the not well sampled high latitude wave environment play a crucial role for the dynamics of various electron populations in the inner magnetosphere. In summary, we present the recently funded EU Horizon 2020 project led by GFZ that will produce a chain of probabilistic modeling forecasts from the Sun to the inner magnetosphere.
Locating the rock hazard and understanding its physical process using seismic signals
Authors: Chang Jui-Ming , Chao Wei-An , Chen Hongey
Published: March 2020

Rock hazard is a common geohazard event that occurs in the orogenic mountain belt and often causes the destruction of road and casualties. The steep topography, fractured bedrock and frequent earthquakes favor to happen. Those are usually fast and unpredictable, leading a lack of direct observation of physical process. Recent seismological studies highlighted the rock hazard induced seismic signals could improve understanding of its dynamics. This study focuses on the three provincial highways that cross the Taiwan Island from east to west. The regions along the highways have the complexity in tectonic structure and extreme climate-forced erosion, causing the hazard frequently occurred. In order to understanding seismic features and physical process of rock hazard, we conducted a series of seismic analyses using the seismic records collected form regional seismic network for ten events, which were reported by the government agency. Four of them have the video recordings, which would be helpful to understanding the relationships between physical process (falling, rolling, bouncing and fragmentation), movement type (fall, topple, slump, slide, avalanche or complex) and seismic features. We developed the hybrid method of determination of geohazard event location (GeoLoc) that combines the cross-correlation-based method and the amplitude-attenuation-based approach. We apply the GeoLoc scheme to locate the events recorded by the seismic station with epicentral distance ranging from 2 to 56 kilometers (km) and it helps to reduce the location error. The leading seismic signals of the mass detachment linked to the crack propagation or slope response can be observed, and we also found that the seismic feature caused by fragment of rock block exhibits the higher frequency than the seismic signals corresponding to impaction of rock particles. Our results highlight the possibility of the seismic technique for locating rock hazards distributed along highways in a regional scale and further understanding its physical process. The aforementioned results would be helpful to build the near-real-time monitoring system along the highways for hazard mitigation of events.