julilili42/papers huggingface dataset:
Cenozoic tectonic evolution of the Pamir-Tian Shan convergence zone: evidence from detrital zircon U-Pb provenance analysis
2020-03-09

&amp;lt;p&amp;gt;&amp;lt;span&amp;gt;The Pamir is an along-strike continuation of the Tibet-Himalaya orogen and penetrated ~300 km into the Tarim and Tajik basins in Cenozoic times. This northward indentation led to regional paleoenvironmental changes and facilitated northward transport of the far-field stress from the India-Asia plate boundary. Due to the compressional stress from the India-Asia boundary and Cenozoic lithosphere delamination, the Pamir underwent intense exhumations, which well recorded its Late Cenozoic mountain building processes. However, the very rapid Late Cenozoic exhumation also erased earlier cooling records and hinders a clear understanding of the Early Cenozoic tectonic evolution of Pamir. Thus, the onset and magnitude of the northward movement of Pamir are loosely constrained (Eocene-Late Oligocene) and long debated. In particular, the Early Cenozoic tectonic evolution of Pamir is unclear.&amp;lt;/span&amp;gt;&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;&amp;lt;span&amp;gt;Provenance study of sediments in the adjacent sediment basins is a widely used method to reconstruct the tectonic-geomorphologic evolution of a mountain range. We carried out paleocurrent measurements and detrital zircon analysis of the Cretaceous-Pliocene sediments in the northern Pamir-Tian Shan convergence zone. Our study area, the Tierekesazi section, is located immediately south to the southern Tian Shan and is evolved in the present foreland basin of the southwestern Tian Shan. The provenance data show that the Tian Shan was the primary source area of the northwestern Tarim basin in the Cretaceous. The appearance of the Triassic-Jurassic detrital zircon grains and northward paleo-flow directions in the Eocene (~41 Ma) to Middle Miocene sediments suggest the Pamir became an important source area of the northwestern Tarim basin. Combining with the regional crustal shortening and paleoclimate data, we speculate that the northward indentation of the Pamir initiated before ~41 Ma. In contrast with the northward movement and Middle-Late Miocene accelerated exhumation of the Pamir, the source area of the studied section shifted back to the Tian Shan after the Middle Miocene. It consists with the Middle-Late Miocene uplift of the southwestern Tian Shan. Simultaneously, the crustal shortening of Pamir propagated to its northern foreland. Newly formed fold-and-thrust zones probably blocked the sediment transport from Pamir to the Tierekesazi section, and the present-day east flowing drainage system in the Pamir-Tian Shan convergence zone was established. We infer, in this period, the Pamir likely reached its present position, which is consistent with the appearance of an extreme arid climate in the Tarim basin.&amp;lt;/span&amp;gt;&amp;lt;/p&amp;gt;
Archaeological Sites and Villages of the Mosul Dam Reservoir Survey (1980)
2020-03-09

The dataset describes the archaeological sites and villages now partially covered by the water of the Mosul Dam Reservoir. The dataset offers for the first time information on c.150 archaeological sites detected during a survey carried out by the Iraqi State Organization for Antiquities and Heritage in 1980.
Does it pay off to link functional gene expression to denitrification rates via modelling?
2020-03-09

&amp;lt;p&amp;gt;The abundances of functional genes and transcripts have provided new insights into microbially mediated biogeochemical processes and might improve quantitative predictions of turnover rates.&amp;lt;br&amp;gt;However, the relationship between reaction rates and the gene and transcript abundances may not be a simple correlation.&amp;lt;br&amp;gt;Most mechanistic reaction models cannot predict molecular-biological data, and it is unclear how they can be informed by such data.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;We developed a mechanistic model that considers transcript abundances of denitrification genes, enzyme concentrations, biomass, and solute concentrations as state variables that are interrelated by ordinary differential equations, and thus mechanistically links molecular-biological data to reaction rates.&amp;lt;br&amp;gt;Important features of transcript dynamics can be reproduced with the transcript-based model.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;We calibrated the model using data from a batch experiment with a denitrifying organism at the onset of anoxia.&amp;lt;br&amp;gt;We explored the relationship between transcript abundances and reaction rates by analyzing the model results.&amp;lt;br&amp;gt;The transcript abundances reacted very quickly to substrate concentrations so that we could simplify the model by assuming a quasi steady state of the transcripts.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;We compared our model to a classical Monod-type formulation, which was as good at simulating the concentrations of nitrogen species as the transcript-based model, but it cannot make use of any molecular-biological data.&amp;lt;br&amp;gt;Our results, thus, suggest that enzyme kinetics (substrate limitation, inhibition) control denitrification rates more strongly than the dynamics of gene expression.&amp;lt;/p&amp;gt;
Neogene Exhumation History along TRANSALP: Insights from Low Temperature Thermochronology and Thermo-Kinematic Models
2020-03-09

&amp;lt;p&amp;gt;Many convergent orogens such as the eastern European Alps display an asymmetric doubly-vergent wedge geometry. Loci of deepest exhumation are located above the overriding retro-wedge, whereas increased fault activity occurs in the pro-wedge on the subducting plate. The main drainage divide separates steeper from more gently sloping topography on the two wedges of different critical taper. We performed apatite and zircon (U-Th)/He analyses densely spaced along the TRANSALP geophysical transect in combination with thermo-kinematic models based on cross-section balancing. Our new low temperature thermochronology data and thermo-kinematic model results underline (i) deepest levels of exhumation across the Tauern Window until the Pliocene and (ii) higher Late Neogene exhumation rates south of the Periadriatic Fault relative to the north, while seismic activity is focussed across the Southern Alps. Our proposed mantle-to-surface link positions the retro-wedge north of the Periadriatic Fault subsequent to subduction polarity reversal during continental collision. Present-day drainage divide migration trends and imaged locations of mantle-lithospheric slabs beneath TRANSALP suggest ongoing, slow slab reversal since Adriatic indentation in the Eastern Alps.&amp;amp;#160;&amp;lt;/p&amp;gt;
The upper 2121 m at EastGRIP - Results from physical properties of NEGIS
2020-03-09

&amp;lt;div&amp;gt; &amp;lt;div&amp;gt; &amp;lt;div&amp;gt; &amp;lt;p&amp;gt;Here we present the ice microstructure and CPO (c-axes fabric) data from the upper 2121 m of the EastGRIP ice core, an on-going deep drilling project on the North East Greenland Ice Stream. Understanding ice flow behaviour of fast flowing ice streams is crucial for accurate projections of future global sea level rise, but is still poorly understood due to e.g. missing observational fabric data from ice streams.&amp;lt;/p&amp;gt; &amp;lt;p&amp;gt;The presented CPO patterns found at EastGRIP show (1) a rapid evolution of c-axes anisotropy compared to deep ice cores from less dynamic sites, (2) a CPO evolution towards a strong vertical girdle and (3) CPO patterns that have not previously been directly observed in ice. Furthermore, data regarding grain properties (e.g. grain size) and indications of dynamic recrystallization, already at shallow depths, are presented.&amp;lt;/p&amp;gt; &amp;lt;p&amp;gt;The ice CPO shows a clear evolution with depth. In the first measurements at 111 m depth a broad single maximum distribution is observed, which transforms into a crossed girdle CPO (196-294 m). With increasing depth, an evolution towards a vertical girdle c-axes distribution occurs. Below 1150 m the CPO evolves into a vertical girdle with a higher density of c-axes oriented horizontally, a novel CPO in ice. These CPO patterns indicate a depth-related change in deformation modes, from vertical compression to extensional deformation along flow.&amp;lt;/p&amp;gt; &amp;lt;p&amp;gt;Grain size values are similar to results from other Greenlandic deep ice cores. Grain size evolution is characterized by an increase until 500 m depth, a decrease until 1360 m depth and mainly constant values in the Glacial. These findings are accompanied by indications of an early onset of dynamic recrystallisation e.g. irregular grain shapes, protruding grains and island grains.&amp;lt;/p&amp;gt; &amp;lt;p&amp;gt;The presented high-resolution data enable, for the very first time, a detailed and data- based look into a fast-flowing ice stream and are an important step towards a better understanding of the rheology of ice and its flow behaviour.&amp;lt;/p&amp;gt; &amp;lt;/div&amp;gt; &amp;lt;/div&amp;gt; &amp;lt;/div&amp;gt;
Urban tracers for the characterization of particle transport processes in an agricultural catchment
2020-03-09

&amp;lt;p&amp;gt;Well-established relations between concentrations of total suspended solids (TSS) and the hydrophobic polycyclic aromatic hydrocarbons (PAHs) in bulk water samples make PAH ideal tracers to understand water and solid transport in catchments during high discharge events. In the study presented here, we trace particle-bound PAH concentrations in the Ammer River, Germany (annual mean discharge of 0.87 m&amp;amp;#179; s&amp;lt;sup&amp;gt;-1&amp;lt;/sup&amp;gt;), during a rain event to deepen knowledge on particle origin and hydrological processes in the catchment. High-resolution temporal monitoring of discharge, TSS, particle characteristics, and PAHs was conducted over the course of an event at two sampling sites at the Ammer River. The sampling sites are located in the upper catchment and ~ 8km downstream of the upper sampling site at the outlet of the gauged catchment (134 km&amp;amp;#178;), while the downstream sampling sites integrates inflowing water from tributaries and a wastewater treatment plant. High PAH particle loading demonstrates that particles in the river originate mainly from urban areas, introduced into the stream via combined sewer systems located in the upper catchment. These particles dominate the suspended particle flux over the temporal course of the event. Despite the integral suspended particle flux being nearly constant in between both sampling sites, particle quality changes which is represented by a decreased integral PAH flux and an increasing proportion of particulate organic carbon in the suspended particles. Decrease of PAH particle loading in the downstream direction suggest dilution by &amp;amp;#8216;cleaner&amp;amp;#8217; particles from either un- or less contaminated or possibly leached sediments entering into the river. This shows that particle exchange between suspended and river bed sediments is more pronounced in downstream direction, demonstrating that sediment mobilisation plays a role for the overall particle flux. These results suggest that the catchment response of the Ammer River regarding the particle flux during rainfall is mainly dominated by the combined sewer system though particle exchange processes are also relevant. Urban tracers are hence helpful for understanding solid transport in catchments.&amp;lt;/p&amp;gt;
Synthetic sampling for spatio-temporal land cover mapping with machine learning and the Google Earth Engine in Andalusia, Spain
2020-03-09

&amp;lt;p&amp;gt;Land cover information plays an essential role for resource development, environmental monitoring and protection. Amongst other natural resources, soils and soil properties are strongly affected by land cover and land cover change, which can lead to soil degradation. Remote sensing techniques are very suitable for spatio-temporal mapping of land cover mapping and change detection. With remote sensing programs vast data archives were established. Machine learning applications provide appropriate algorithms to analyse such amounts of data efficiently and with accurate results. However, machine learning methods require specific sampling techniques and are usually made for balanced datasets with an even training sample frequency. Though, most real-world datasets are imbalanced and methods to reduce the imbalance of datasets with synthetic sampling are required. Synthetic sampling methods increase the number of samples in the minority class and/or decrease the number in the majority class to achieve higher model accuracy. The Synthetic Minority Over-Sampling Technique (SMOTE) is a method to generate synthetic samples and balance the dataset used in many machine learning applications. In the middle Guadalquivir basin, Andalusia, Spain, we used random forests with Landsat images from 1984 to 2018 as covariates to map the land cover change with the Google Earth Engine. The sampling design was based on stratified random sampling according to the CORINE land cover classification of 2012. The land cover classes in our study were arable land, permanent crops (plantations), pastures/grassland, forest and shrub. Artificial surfaces and water bodies were excluded from modelling. However, the number of the 130 training samples was imbalanced. The classes pasture (7&amp;amp;#160;samples) and shrub (13&amp;amp;#160;samples) show a lower number than the other classes (48, 47 and 16&amp;amp;#160;samples). This led to misclassifications and negatively affected the classification accuracy. Therefore, we applied SMOTE to increase the number of samples and the classification accuracy of the model. Preliminary results are promising and show an increase of the classification accuracy, especially the accuracy of the previously underrepresented classes pasture and shrub. This corresponds to the results of studies with other objectives which also see the use of synthetic sampling methods as an improvement for the performance of classification frameworks.&amp;lt;/p&amp;gt;
Soil formation and biological soil crust development in glacier forelands of Svalbard (High Arctic)
2020-03-09

&amp;lt;p&amp;gt;Over the last decades, a progressive glacier melting has been detected induced by climate change which cause a rapid enlargement of ice-free areas in glacier forelands in Arctic, Antarctic and Alpine regions. These recently deglaciated areas represent highly dynamic environments in terms of vegetation development and soil formation. Tundra plant communities of glacier forelands mainly consist of cryptogamic species forming biological soil crusts (BSCs) on the surface. These BSCs are known to promote the accumulation of aeolian particles and organic material being relevant to soil formation. It is important to understand both BSC development and soil formation in glacier forelands as fundamental to future development of mature tundra which contributes to an increase in soil organic carbon (SOC) and nitrogen (N) stocks in soil. The heterogeneous terrain of glacier forelands affects the spatial variation in both soil and vegetation characteristics which are additionally influenced by the distance to the glacier terminus. This study focuses on the spatial variation in soil and BSC characteristics in Arctic glacier forelands of Svalbard using multi-scale contextual soil mapping (CSM) and Euclidean distance fields (EDF). The data set comprises of soil (SOC, N, texture) and BSC characteristics (species composition, percent cover) from 168 sampling locations as well as terrain covariates (elevation, slope, aspect, curvature) at several scales using CSM and spatial covariates (EDF). Random forests (RF) are used to analyse the relationships between the covariates and soil and BSC characteristics, respectively.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;Preliminary results show a good quality of the RF models (R&amp;amp;#178;/RMSE) which is similar for SOC (0.41/6.19) and N (0.44/0.22). Elevation, curvature and slope at large scales are the most important covariates to explain the spatial variation in SOC and N. On large scales, these covariates represent the distance to the glacier terminus and generally explain the increase in SOC and N with increasing distance from the glacier terminus.&amp;amp;#160; Additionally, elevation at small scales represents relevant issues of predominant geomorphologic features signature (e.g. moraine topography) to soil formation and BSC development. Analyses of the spatial variation and interrelationships of soil and BSC characteristics are still ongoing and further results will be presented at EGU 2020.&amp;lt;/p&amp;gt;
Characterize the catchment regime by applying optimal monitoring strategies
2020-03-09

&amp;lt;p&amp;gt;Commonly, chemical catchment regimes are described by a simple regression slope of log-concentrations versus log-discharges measured in the catchment outlet river. The slope value of these plots defines the chemical regime of a catchment. A slope=-1 corresponds to a constant contaminant release subject to dilution by rainfall (an unrealistic extreme but needed as a base flow); whereas a slope=0 means that there are chemostatic effects in the catchment or a washout of contaminants at a constant concentration. However, reality shows that actual time-series measurements of discharge and concentrations conflict with this naive representation since the measurements show temporal hysteresis that defies regression assumptions (i.e. that regression residuals must be uncorrelated). To represent this time interaction beyond regression, we design a simple stochastic time-series model that accounts for fluctuating concentration release and transport with memory. In this work, we also establish how to get the observation data required for a robust estimation of the slope with the least effort. To show the capability of our proposed model and method, we apply a retrospective optimal design of experiments to a high-frequency data series of nitrate concentration (collected by online probes) and discharge of a real catchment in Germany. We thin out the data by applying frequency and event-based monitoring strategies to find out the key components of the strategies that best predict the catchment behavior. Results indicate that our catchment under study (the Ammer catchment in southwestern Germany) is relatively close to a chemostatic type catchment and that our stochastic model, in fact, provides more accurate results for small data sets. Also, optimal data collection schemes for this purpose should be event-based, considering both high and low extremes of discharge that are spread out over time.&amp;lt;/p&amp;gt;
Organic carbon sorbed to reactive iron minerals released during permafrost collapse
2020-03-09

&amp;lt;p&amp;gt;The release of vast amounts of organic carbon during thawing of high-latitude permafrost is an urgent issue of global concern, yet it is unclear what controls how much carbon will be released and how fast it will be subsequently metabolized and emitted as greenhouse gases. Binding of organic carbon by iron(III) oxyhydroxide minerals can prevent carbon mobilization and degradation. This &amp;amp;#8220;rusty carbon sink&amp;amp;#8221; has already been suggested to protect organic carbon in soils overlying intact permafrost. However, the extent to which iron-bound carbon will be mobilized during permafrost thaw is entirely unknown. We have followed the dynamic interactions between iron and carbon across a thaw gradient in Abisko (Sweden), where wetlands are expanding rapidly due to permafrost retreat. Using both bulk (selective extractions, EXAFS) and nanoscale analysis (correlative SEM and nanoSIMS), we found that up to 19.4&amp;amp;#177;0.7% of total organic carbon is associated with reactive iron minerals in palsa underlain by intact permafrost. However, during permafrost collapse, the rusty carbon sink is lost due to more reduced conditions which favour microbial Fe(III) mineral dissolution. This leads to high dissolved Fe(II) (2.93&amp;amp;#177;0.42 mM) and organic carbon concentrations (480.06&amp;amp;#177;34.10 mg/L) in the porewater at the transition of desiccating palsa to waterlogged bog. Additionally, by combining FT-ICR-MS and greenhouse gas analysis both in the field and in laboratory microcosm experiments, we are currently determining the fate of the mobilized organic carbon directly after permafrost collapse. Our findings will improve our understanding of the processes controlling organic carbon turnover in thawing permafrost soils and help to better predict future greenhouse gas emissions.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;&amp;amp;#160;&amp;lt;/p&amp;gt;
Comparison of seismic velocities derived from crystal orientation fabrics and ultrasonic measurements on an ice core
2020-03-09

&amp;lt;p&amp;gt;Understanding the internal structure of glacier ice is of high interest for studying ice flow mechanics and glacier dynamics. The micro-scale deformation mechanisms cause a reorientation and alignment of the ice grains resulting in a polycrystalline structure with a strong anisotropy. By studying the crystal orientation fabric (COF), details about past and ongoing ice deformation processes can be derived. Usually, obtaining COF requires a work-intensive ice core analysis, which is typically carried out only at a few ice core samples. When similar information can be obtained from geophysical, for example, seismic experiments, a more detailed and more continuous image about the ice deformation would be available. &amp;lt;br&amp;gt;For checking the suitability of seismic data for such purposes, we have analysed the COF of several ice core samples extracted from Rhone Glacier, a temperate glacier located in the Central Swiss Alps. The COF analysis yield a polycrystalline elasticity tensor for a given volume of ice, from which we predicted seismic velocities for acoustic waves originating from any azimuth and inclination. The seismic data predicted were then verified with ultrasonic experiments conducted along the ice core in the vicinity of the analysed COF. Additional X-ray tomographic measurements yield further constraints about the microstructure, especially about the air bubble content in the ice affecting the data of the ultrasonic experiments. Predicted and measured velocities generally show a good match. This is a very encouraging result, because it suggests that in-situ measurements of seismic velocities can be employed for studying ice deformation. A possible option is to perform seismic cross-hole measurements within an array of boreholes drilled into the glacier ice.&amp;lt;/p&amp;gt;