Earth Processes Research Articles

Stable Sn isotope signatures of Mid-ocean ridge basalts

The constraint of Sn isotope composition of the Earth's mantle is the prerequisite for understanding planet formation with Sn isotopes and Sn isotope fractionation in terrestrial reservoirs. However, previous estimates of the Sn isotope composition of the Earth's mantle are hampered by the small number of mantle-related samples. In this study, we analyzed Sn stable isotope compositions of 27 basalts from geochemically and geologically diverse mid-ocean ridge segments, to constrain the Sn isotope composition of the depleted mantle source. The spread of Sn isotope compositions for the 27 different mid-ocean ridge basalts (MORBs) is limited, with δ122/118SnBHVO-2 (delta notation of 122Sn/118Sn ratios relative to USGS BHVO-2 basalt standard) values ranging from −0.051 ± 0.015‰ to 0.209 ± 0.016‰ (δ122/118Sn3161a from 0.280 ± 0.015 to 0.540 ± 0.016‰), despite great geochemical and geographical diversities of the samples. The slightly higher δ122/118SnBHVO-2 value (up to 0.209 ± 0.016‰ (δ122/118Sn3161a up to 0.540 ± 0.016‰)) of one MORB sample appears to be caused by post-eruptive alteration of the basalts. Other than that, the δ122/118SnBHVO-2 values of the MORB samples do not show correlations with sample latitude, spreading rate of mid-ocean ridge, MgO content of the bulk rock samples, and partial melting index Na8.0 (defined as [Na2O] + 0.373 × [MgO] − 2.98), implying that Sn isotopes do not fractionate significantly during MORB melt generation and evolution processes. This study confirms the limited Sn isotopic variability between fresh MORBs globally, pointing to the Sn isotopic homogeneity of the depleted mantle source. Using these new MORB data, we proposed an estimate of the δ122/118SnBHVO-2 value for the Earth's depleted mantle to be 0.036 ± 0.087‰ (δ122/118Sn3161a of 0.367 ± 0.087‰) (2SD, N = 12). This value provides a reference point for understanding the planetary and magmatic processes of Earth from a Sn isotope perspective.

Large mass strandings of selected odontocete species: statistics, locations, and relation to earth processes

Larger mass strandings of open ocean odontocetes (toothed whales) of 10+ animals are examined with a compilation of 710 worldwide events. Sixspecies form 96% of events (false killer, long-finned pilot, melon-headed, short-finned pilot, sperm and white whales), with beaked, killer, andpygmy killer whales forming 4%. Site type was determined for 630 events – three-quarters (76%) are in bays, 14% in shallow topographicallycomplex areas (estuarine environments, straits, keys, reef and coastal lagoons), 8% on relatively unindented coasts, with ice entrapment (of killerwhales) and miscellaneous categories being 2%. For the 76% of events in bays, sites with headland-bay character make up 42%, spit-bays 20%(even though there are only four of them), indented bays 9% and unspecified bay types 5%. Headland-bays and spit-bays become stranding sitesthrough the properties endowed them by their mechanisms of formation and maintenance, but these mechanisms differ greatly for the two.Breakwaters, groyne series, tides, partial burial, and violent storms also appear as themes. Nearshore slopes are less than 1° for 94 of 105 siteshaving bathymetry information, with only two reaching or exceeding 3°. Some types of potential stranding sites can be identified by simplequantitative specifications for planform, sediment size, and seabed slope, although strandings will not necessarily occur there. There is an indicationthat larger strandings are globally correlated with areas of higher oceanic primary productivity near landmasses and oceanic islands, but quantitativestudies are needed to clarify any such possible relationship. There is also an indication that larger strandings are associated with plate tectonics,with few events being seen on the steeper swell resistant active western margins of South America and South Island (New Zealand) in particular.In contrast several larger events are recorded for the relatively older passive margins of the south-eastern sides of these two landmasses, putativelybecause waves and swell have had time to construct stranding sites on them. Similarly, few larger events are seen for steeper shores adjacent tocoastal highlands, such as those of South Africa and Brazil. These observations indicate previously unsuspected relations between the phenomenonof odontocete mass strandings and global scale earth and ocean processes, but they are essentially hypotheses in need of more quantitativeexamination.

Hundred years of geophysics (1834–1933)

Geophysics is relatively a new discipline in comparison to physics or geology. Contrary to general perception as an ancillary to geology, the discipline has been developed with a distinct focus of using the principles and methods of physics for the earth processes. Geophysics was born in the nineteenth century as a necessary element of theoretical geography. Academicians and researchers in the field of geography played chief roles from its birth to its present level of maturity. Historical scholarship in this paper provides an account of the development of the discipline over hundred years from its inception in the early nineteenth century. The article covers, how the discipline was conceptualised and what necessary steps were taken, such as establishing learned societies, publishing technical journals and text books, endowing university chairs, opening up departments and course curriculum, and most importantly, appearing as a primary discipline to cater to exploration for mineral resources.

Using acoustic velocities and microimaging to probe microstructural changes caused by thermal shocking of tight rocks

Introduction: Large scale, Earth processes and bulk rock properties are influenced by underpinning, dynamic, microstructures within rocks and geomaterials. Traditionally, the amount of porosity has been considered the primary control on important bulk rock properties like seismic wave velocities (Vp and Vs) and permeability. However, in tight rocks, velocity and permeability (k) can change substantially despite small changes in the amount of porosity during cracking. Therefore, other microstructural features inherent to given lithologies, such as heterogeneity and anisotropy in mineral properties are considered as factors controlling these bulk rock properties. Understanding which microstructural features control Vp, Vs, and permeability in tight rocks is useful in applications like enhanced geothermal systems (EGS), where thermal shocking is used to increase permeability. Thermal shocking involves injecting surface water into the subsurface to cool mineral crystals, induce contraction of crystals, and cause thermal cracking.Methods: We tested three tight lithologies with unique microstructures; granodiorite (SWG), basalt (PTB), and carbonate (MSA). We simulated thermal shocking by slowly heating samples to 350°C and then quenching them. We chose a temperature of 350°C because thermal shocking at this temperature is not well documented in literature, and this temperature is relevant to EGS. Using time-lapse microimaging, we assessed how thermal cracking occurs in each lithology and explored how thermal cracks influence connected porosity, Vp, Vs, and k.Results: Microimaging shows extensive cracking in the SWG and MSA lithologies, and little to no cracking in PTB with thermal shocking treatment. Vp and Vs became more pressure sensitive, and elastic moduli decreased with treatment for all lithologies. This may be caused by reduced stiffness between mineral crystal boundaries with treatment.Discussion: Lithologies with minerals that have anisotropy of or a wide range in thermal conductivity and/or thermal expansion coefficients can have increased thermal cracking. In thermally shocked SWG and MSA, Vp and Vs are good indicators of thermal cracking and k increases, but less so in PTB. Lithologies like PTB may require multiple thermal shock stimulations to increase permeability. Our results highlight how micro-scale changes influence bulk rock properties and when we can monitor permeability increases and microscale thermal cracking with Vp and Vs.

On the Identification of Agroforestry Application Areas Using Object-Oriented Programming

The detection of possible areas for the application of agroforestry is essential and involves the usage of various technics. The recognition of forest types using satellite or aerial imagery is the first step toward this goal. This is a tedious task involving the application of remote sensing techniques and a variety of computer software. The overall performance of this approach is very good and the resulting land use maps can be considered of high accuracy. However, there is also the need for performing high-speed characterization using techniques that can determine forest types automatically and produce quick and acceptable results without the need for specific software. This paper presents a comprehensive methodology that uses Normalized Difference Vegetation Index (NDVI) data derived from the Moderate Resolution Imaging Spectroradiometer instrument (MODIS) aboard the TERRA satellite. The software developed automatically downloads data using Google Earth Engine and processes them using Google Colab, which are both free-access platforms. The results from the analysis were exported to ArcGIS for evaluation and comparison against the CORINE land cover inventory using the latest update (2018).

Discrimination of thermodynamic and kinetic contributions to the heavy rare earth element patterns in metamorphic garnet

AbstractVariations of rare earth element (REE) concentrations in metamorphic garnet are an important source of information of geodynamic and geochemical processes in the deeper Earth. In order to extract this information, the thermodynamic equilibrium and kinetic contributions of the REE uptake in garnet must be distinguished and quantified. Utilizing high‐resolution trace element and μ‐Raman mapping together with combined thermodynamic–geochemical–diffusion models, we demonstrate that the equilibrium and kinetic aspects of the REE uptake in metamorphic garnet can be discriminated by interpreting 2D trace element mapping in a single sample. The heavy (H) REE (Tb to Lu) zoning in the investigated garnet from a high‐pressure blueschist comprises an inner part with an overall decrease from core to inner rim, followed by a concentric zone of HREE enrichment and a drastic HREE decrease towards the outermost rim. The central peak in the garnet core decreases in intensity with decreasing atomic number of the REE. The broad overall shape of this pattern resembles those often observed in metamorphic garnet from different rock types and tectonic settings. Superimposed on this trend is a concentric pattern of minor recurring fluctuations in the HREE concentrations with at least six regularly spaced sets of peaks and troughs along the entire garnet radius. Comparison of the observed inclusion suite, the trace element maps and thermodynamic–geochemical models show that the inner part with decreasing HREE concentrations results from fractional garnet growth in an unchanged mineral assemblage, whereas the REE enrichment zone is caused by the breakdown of titanite. We suggest that the width of the central peak is controlled by the bulk permeability of the interconnected transport matrix and the fraction of matrix minerals that the garnet equilibrates with. The superimposed REE fluctuations result from changing element transport properties of the host rock and mark recurring changes from equilibrium REE uptake to transport‐limited REE uptake in garnet. Such fluctuating element transport properties can be best explained by pulse‐like fluid fluxes that rhythmically change the interconnectivity of the intercrystalline transport matrix. Increasing numbers of published spatially highly resolved REE analyses show that such trace element fluctuations are common in metamorphic garnet indicating that recurring changes in rock permeabilities due to pulsed fluid fluxes are a common phenomenon during metamorphism.

How Weather Affects over Time the Repeatability of Spectral Indices Used for Geological Remote Sensing

Geologic remote sensing studies often targets surface cover that is supposed to be invariant or only changing on a geological timescale. In terms of surface material characteristics, this holds for rocks and minerals, but only to a lesser degree for soils (including alluvium, colluvium, regolith or weathered outcrop) and not for vegetation cover, for example. A view unobstructed by clouds, vegetation or fire scars is essential for a persistent observation of surface mineralogy. Sensors with a continuous multi-temporal operation (e.g., Landsat 8 OLI and Sentinel-2 MSI) can provide the data volume needed to come to an optimal seasonal acquisition and the application of data fusion approaches to create an unobstructed view. However, the acquisition environment always changes over time, driven by seasonal changes, illumination changes and the weather. Consequently, the creation of an unobstructed view does not necessarily lead to a repeatable measurement. In this paper, we evaluate the influence of weather and resulting soil moisture conditions over a 3-year period, with alternating dry and wet periods, on the variance of several “geological” spectral indices in a semi-arid area. Sentinel-2 MSI data are chosen to calculate band ratios for green vegetation, ferric and ferrous iron oxide mineralogy and hydroxyl bearing alteration (clay) mineralogy. The data were used “as provided”, meaning that the performance of the atmospheric correction and geometric accuracy is not changed. The results are shown as time-series for selected areas that include solid rock, beach sand, bare soil and natural vegetation surfaces. Results show that spectral index values vary not only between dry and wet periods, but also within dry periods longer than 45 days, as a result of changing soil moisture conditions long after a last rain event has passed. In terms of repeatability of measurements, an overall low soil-moisture level is more important for long-term stability of spectral index values than the occurrence of minor rain events. In terms of creating an unobstructed view, we found that thresholds for NDVI should not be higher than 0.1 when masking vegetation in geological remote sensing, which is lower than what usually is indicated in literature. In conclusion, multi-temporal data are not only important to study dynamic Earth processes, but also to improve mapping of surfaces that are seemingly invariant. As this work is based on a few selected pixels, the obtained results should be considered only indicative and not as a numerical truth. We conclude that multi-temporal data can be used to create an unobstructed view, but also to select the data that give the most repeatability of measurements. Images selection should not be based on a certain number of days without rain in the days preceding data acquisition but aim for the lowest soil moisture conditions. Consequently, weather data should be incorporated to come to an optimal selection of remote sensing imagery, and also when analyzing multi-temporal data.

Potential of Earth-Based Bamboo Bio-Concrete in the Search for Circular and Net-Zero Carbon Solutions to Construction Industry

In order to limit climate change by achieving goals of cutting emissions down to net-zero by 2050, stronger efforts are needed to reduce the whole life cycle emissions of buildings. Integrating residual bio-based and earth-based solutions to concrete seems to stand out in the sector since these solutions have the potential of lowering materials embodied emissions, and enhancing building thermal performance. However, it is still unclear how environmentally beneficial bio-based and earth-based materials are and how they behave mechanically when they are both integrated into concrete. In order to know their potential applications in the sector, this study aims to evaluate and compare the mechanical performance and environmental profile of Earth-based Bamboo Bio-Concretes (EBBCs) with different earth fractions as partial replacements of the cementitious matrix, by evaluating its Greenhouse Gas (GHG) emissions. For that, it was considered the use of only bio-based aggregates (bamboo waste) instead of mineral ones at a fixed volume fraction of 45%. The methodology involved the: processing and characterization of earth and bamboo; EBBCs dosage study and mechanical testing; consideration of fixed proportions of binders of 30:30:40 (cement: metakaolin: fly ash) which were replaced gradually by earth in the volume fractions of 10%, 15%, and 20%. The Life Cycle Assessment (LCA) was used for accounting GHG emissions. LCA scope was from cradle-to-gate considering biogenic carbon methodology and avoided impacts of incinerating bamboo waste. A sensitive analysis was performed to evaluate the impact of transport distances variation of bamboo waste. Mechanical results point to an increase in EBBCs compressive strength with the increase of earth content until 15% of cementitious matrix replacement. LCA results showed negative embodied GHG emissions in all mixtures with an average of -115,7 kgCO2-eq/m3 mainly due to the high biomass content in mixtures. The increase of earth content from 0% to 20% in the mixtures reduced emissions by 59,7 kgCO2-eq/m3 since the binder’s content was reduced. With that, EBBC seems to be a promising innovative material to help achieve net-zero carbon emission targets and a circular pathway in the building and construction sectors.

A review of the 19th International Symposium on geodynamics and earth tide, Wuhan 2021

Modern geodetic technologies such as high-precision ground gravity measurements, satellite gravity measurements, the global navigation satellite system, remote sensing methods, etc. provide rich observation data for monitoring various geodynamic processes of the global Earth and its surface. The 19th International Symposium on Geodynamics and Earth Tides brought together scientific researchers from 26 countries around the world, shared the application of various measurements in different geoscience issues, covering Earth tidal deformation, oceanic and atmospheric loading effects, earthquake cycle, hydrology, Earth rotation changes, etc., and provided a precious exchange platform for global peers.

The impact of objective and subjective valuations on behaviours: A case study of a rare earth processing plant

Despite the importance of rare earth elements in modern technologies, the establishment of rare earth plants often faces strong opposition from the community due to a fear of environmental impacts. This study examines information about actual and perceived pollution produced by a rare earth plant in Malaysia, Lynas Advanced Material Plant (LAMP), and the community's response to it. A survey of 570 respondents reveals that LAMP is perceived to have a high environmental impact in the long run, although its pollution levels are mostly below the limit set by the authorities. About 18% of respondents have undertaken averting behaviours (AB) such as protest, reduction in outdoor activities, and increased health expenditure. The estimated averting expenditure, excluding migration cost, is about 0.06% of household monthly income. Logit estimations show that perception is a significant determinant of AB, while Tobit estimations indicate that young, male, non-Malays and those exposed to poor surrounding air quality, low levels of trust and perceived high levels of environmental impact will incur additional cost. Rare earth companies and the authorities should therefore find ways to communicate with and gain trust from the locals to reduce their fear and to avoid unnecessary protective actions.

A quantitative recovery process of rare earth in bastnaesite leachate for energy saving and emission reduction

Extraction-precipitation method is a novel separation strategy, a new extraction-precipitant N-lauroyl sarcosine (NLSA) is synthesized in this article. It was found that the extraction-precipitant has a task-specific precipitation ability for rare earth (RE). RE(III) can be recovered quantitatively in the presence of Ca(II), Mg(II), Al(III). When the precipitation rate of RE is 96 %, the precipitation rate of Al is only 6.8 %. The separation coefficient (βRE/Al) reaches 375, and the precipitation of Ca(II) and Mg(II) is negligible. The solid complex produced in the precipitation process has a large particle size which is easy to be separated. In addition, the precipitation can be completely stripped with 6 mol/L hydrochloric acid, and the REO concentration of stripping solution reaches 255 g/L. After 5 cycles of extraction-precipitation, the specific precipitation of NLSA on RE remains basically unchanged. Mechanism analyses indicate that the extraction-precipitation process is cation exchange. The specificity of the precipitation process can be attributed to the steric hindrance of amide bonds hindering the coordination of Al (III). Finally, a novel enrichment process of bastnaesite leachate is developed to enrich RE, which can effectively remove impurities, so as to effectively avoid the generation of impurity removal residue. Also the enrichment process can reduce energy consumption and carbon emission. The pulverized coal consumption in this process is only 6.25 % of the existing industrial process, and the carbon emission has been decreased by 93.75 %.

Topographic gradients of soil physical, chemical, and mineralogical properties in central Kentucky sinkholes

AbstractAn estimated 20% of the world's land surface is underlain by lithologies favorable for karst formation. Karst features (e.g., sinkholes) and soils coevolve, likely influencing local pedogenesis, soil carbon storage, and hydrologic patterns. While karst is widespread, our understanding of the influence of karst geomorphology on pedogenesis remains limited. To better estimate the impact of karst geomorphology on pedogenesis, we characterized nine pedons as a function of landscape position (i.e., toposequence) in two subsidence sinkholes located in the Inner Bluegrass physiographic region of central Kentucky; we characterized a suite of soil physical, chemical, and mineralogical properties. The Inner Bluegrass is underlain by a phosphatic limestone and is susceptible to karst formation. Expectedly, total carbon was greater in lowland positions relative to upland landscape positions. However, inverse relationships between elevation and clay content, selective iron, aluminum, and silicon extracts contradicted previous toposequence trends. Clay mineralogy differences between toeslope and summit positions suggested sediment transport from summit to toeslope positions. Karst geomorphology may limit pedogenesis and facilitate more rapid material export through karst conduits compared to other lithologies. Given the extent of karst terrains and lithologies susceptible to karst formation, future work is needed to understand the magnitude of the impact of karst on pedogenesis and other earth system processes.

Analysis of category level performance on the Praxis® earth and space science: Content knowledge test: Implications for professional learning

A large body of work has shown that science teacher knowledge is one of the most fundamental components of effective teaching and learning. Our study analyzes the Praxis® Earth and Space Science Content Knowledge Test (ESS CKT) from May 2006 to June 2016. We present one of the largest datasets comprising 11,273 ESS teacher candidates in order to provide information about their demonstrated ESS CK. Understanding that the benefits associated with teacher retention outweigh the cost of hiring new teachers, our results can be used to design targeted professional learning (PL) experiences for pre- and inservice teachers. Findings from this study are particularly useful while planning inservice topic specific PL for teachers pre- and inservice ESS teachers by answering the following research questions (1) How have examinees performed as a whole in each category on the Praxis® ESS CKT? (2) Which personal and/or professional characteristics are most associated with examinee performance in each category and how does this inform professional learning? Examinee performance at the category level was analyzed through a five-part process: 1. Confirmatory Factor Analysis: 2. Percent correct; 3. Regression; 4. ANOVA; 5. Scaled points lost. Our findings revealed that examinees demonstrated strongest performance in the topics assessing Earth’s Atmosphere & Hydrosphere, Earth Materials & Surface Processes, and Tectonics & Internal Earth Processes and identity History of the Earth and its Life-Forms as topics in need of support. Across categories, we found differences in achievement associated with undergraduate major, gender, and ethnicity. Test-takers with geoscience majors consistently lost fewer points than their out-of-field counterparts, that men outperformed women in the study, and White test-takers lost fewer scaled points than Black and Hispanic candidates. Our recommendations include reviewing our results for alignment with state standards in order to develop comprehensive CK development that will be used as an anchor for focused support on those topics where test-takers tend to demonstrate lowest proficiency.

Understanding of mobility limiting factors in solution grown Al doped ZnO thin film and its low temperature remedy

The solution grown doped ZnO based transparent electrode has shown great potential in future generation flexible and smart devices due to its abundance in earth, low cost, simple and low temperature synthesis process. But solution grown doped ZnO possesses one major drawback, its mobility decreases rapidly with an increase in doping concentration. To eliminate this issue, the understanding of factors that limiting mobility is a prerequisite. But till date, there are very limited resources with detailed understanding of mobility limiting factors in solution grown TCO. Here in this report, with the morphological, optical and electrical investigations, the mobility limiting factor comes out to be surface related property and assigned to be the defects related to surface adsorbed oxygen and oxygen species at the surface. Furthermore, we have modified the surface to remove the surface adsorbed oxygen species by a low temperature (70 °C) simple solution process. Surface modified sample shows more than two orders of improvement in resistivity without any significant change in the transparency in visible range.

Reorganization of continent‐scale sediment routing based on detrital zircon and rutile multi‐proxy analysis

AbstractThe duration and extent of sediment routing systems are intrinsically linked to crustal‐ to mantle‐scale processes. Therefore, distinct changes in the geodynamic regime may be captured in the detrital record. This study attempts to reconstruct the sediment routing system of the Canning Basin (Western Australia) during the Early Cretaceous to decipher its depositional response to Mesozoic‐Cenozoic supercontinent dispersal. Specifically, we reconstruct source‐to‐sink relationships for the Broome Sandstone (Dampier Peninsula) and proximal modern sediments through multi‐proxy analysis of detrital zircon (U–Pb, Lu–Hf and trace elements) and detrital rutile (U–Pb and trace elements). Multi‐proxy comparison of detrital signatures and potential sources reveals that the majority of the detrital zircon and rutile grains are ultimately sourced from crystalline basement in central Australia (Musgrave Province and Arunta region) and that proximal sediment supply (i.e., Kimberley region) is negligible. However, a significant proportion of detritus might be derived from intermediate sedimentary sources in central Australia (e.g., Amadeus Basin) rather than directly from erosion of crystalline basement. Broome Sandstone data are consistent with a large‐scale drainage system with headwaters in central Australia. Contextualization with other broadly coeval drainage systems suggests that central Australia acted as a major drainage divide during the Early Cretaceous. Importantly, reorganization after supercontinent dispersal is characterized by the continuation of a sediment pathway remnant of an earlier transcontinental routing system originating in Antarctica that provided a template for Early Cretaceous drainage. Review of older Canning Basin strata implies a prolonged denudation history of central Australian lithologies. These observations are consistent with the long‐lived intracontinental tectonic activity of central Australia governing punctuated sediment generation and dispersion more broadly across Australia and emphasize the impact of deep Earth processes on sediment routing systems.

An energy-based theory of rock faulting

Faulting of rocks is a dominant earth process that governs small-scale fracturing, formation of tectonic plate boundaries, and earthquakes occurrence. Since the 18th century, the mechanics of rock faulting was commonly analyzed with the Coulomb criterion that offers empirical, useful tools for scientific and engineering applications. Here we revisit the processes of rock faulting by an alternative approach that incorporates elastic energy, strain-state, and three-dimensional deformation; these mechanical fundamentals are missing in Coulomb criterion. We propose that a stressed rock-body fails as two conditions are met: (A) The elastic energy generated by the loading system equals or exceeds a critical energy intensity that is required for the faulting process; (B) To maintain physical continuity, the internal strain of the stressed rock-body due to slip and dilation along the developing faults equals the strain-state created by the loading system. Our simulations reveal that meeting these energy and strain conditions requires an orthorhombic, polymodal fault geometry that is comparable to natural and experimental fault systems. The application of our formulation to hundreds of rock-mechanics experiments provides a new, comprehensive benchmark for rock-faulting.

An undergraduate research experience in earth science education that benefits pre-service teachers and in-service earth science teachers

Three cohorts of six pre-service Earth Science teachers (undergraduate majors in Earth Science Education) participated in summer research experiences focused on developing dynamic physical models of Earth processes to help middle and high school students understand complex concepts and confront misconceptions. The pre-service teachers used published criteria for evaluating models. Participants deepened their understanding of specific Earth Science concepts and broadened their perceptions of effective, student-centered, constructivist pedagogical practices through the use of models and model-based learning. Our pre-service Earth Science teachers achieved the same benefits that STEM majors report from their undergraduate research experiences, including better understanding of the nature of science, gains in problem-solving and communication skills, increased confidence, collaborative skills and comfort in working independently. Evaluation of the research experience via the Undergraduate Research Student Self-Assessment indicated that pre-service teachers reported higher gains than STEM majors in nearly all categories. The pre-service teachers presented the results of their projects to in-service teachers in professional development workshops at a science teachers’ conference. In-service teachers’ responses to these workshops were uniformly positive (98.2%; n = 57). Unlike most professional development activities in which participants benefit, but presenters may not, these professional development activities benefited participants and presenters alike.

Coffee Silverskin: Chemical and Biological Risk Assessment and Health Profile for Its Potential Use in Functional Foods.

The coffee supply chain is characterized by a complex network with many critical and unsustainable points producing a huge amount of waste products. Among these, coffee silverskin (CS), the only by-product of the coffee roasting phase, has an interesting chemical profile that suggests potential use as a food ingredient. However, few data on its safety are available. For this reason, the purpose of the study was to assess the occurrence of chemical and biological contaminants in CS, and the resulting risk due to its potential consumption. Essential, toxic, and rare earth elements, polycyclic aromatic hydrocarbons (PAHs), process contaminants, ochratoxin A (OTA), and pesticides residues were analyzed in three classes of samples (Coffea arabica CS, Coffea robusta CS, and their blend). Furthermore, total mesophilic bacteria count (TMBC) at 30 °C, Enterobacteriaceae, yeasts, and molds was evaluated. The risk assessment was based upon the hazard index (HI) and lifetime cancer risk (LTCR). In all varieties and blends, rare earth elements, pesticides, process contaminants, OTA, and PAHs were not detected except for chrysene, phenanthrene, and fluoranthene, which were reported at low concentrations only in the arabica CS sample. Among essential and toxic elements, As was usually the most representative in all samples. Microorganisms reported a low load, although arabica and robusta CS showed lower contamination than mixed CS. Instead, the risk assessment based on the potential consumption of CS as a food ingredient did not show either non-carcinogenic or carcinogenic risk. Overall, this study provides adequate evidence to support the safety of this by-product for its potential use in functional foods.

Urban land use land cover mapping in tropical savannah using Landsat-8 derived normalized difference vegetation index (NDVI) threshold

Generation of land use/land cover map at different spatial scales using satellite remote sensing data has been in practice as far back as early 1970s. Since then, research focus has been on the development of classification steps and improving the quality of the resulting maps. In recent times, the demand for detailed high accuracy land-use and land-cover (LULC) data has been on the increase due to the growing complexity of earth processes, while, at the same time, processing step is becoming more complex. This paper explores Landsat 8 derived normalized difference vegetation index (NDVI) threshold for the purpose of simplifying land cover classification process. NDVI images of January, May and December, 2018, representing dry, wet and harmattan seasons were generated. Thereafter, NDVI values corresponding to the location of a set of training data representing the target urban land covers (water, built-up area, soil, grassland and shrub) were extracted. Using the statistics of the extracted values, NDVI threshold for the respective land cover type were determined for the classification process. Finally, the classification accuracy was evaluated using the unbiased matrix coefficient technique which produced overall accuracy of 71.3%, 46.4% and 75.6% at 95% confidence limit for the months of January, May and December of the year review respectively. The result has shown that NDVI threshold is a simple and practical alternative to obtain LULC map at a reasonable time with a few data.

Achievements and Prospects of Global Broadband Seismographic Networks After 30 Years of Continuous Geophysical Observations

AbstractGlobal seismographic networks (GSNs) emerged during the late nineteenth and early twentieth centuries, facilitated by seminal international developments in theory, technology, instrumentation, and data exchange. The mid‐ to late‐twentieth century saw the creation of the World‐Wide Standardized Seismographic Network (1961) and International Deployment of Accelerometers (1976), which advanced global geographic coverage as seismometer bandwidth increased greatly allowing for the recording of the Earth's principal seismic spectrum. The modern era of global observations and rapid data access began during the 1980s, and notably included the inception of the GEOSCOPE initiative (1982) and GSN (1988). Through continual improvements, GEOSCOPE and the GSN have realized near‐real time recording of ground motion with state‐of‐art data quality, dynamic range, and timing precision to encompass 180 seismic stations, many in very remote locations. Data from GSNs are increasingly integrated with other geophysical data (e.g., space geodesy, infrasound and Interferometric Synthetic Aperture Radar). Globally distributed seismic data are critical to resolving crust, mantle, and core structure; illuminating features of the plate tectonic and mantle convection system; rapid characterization of earthquakes; identification of potential tsunamis; global nuclear test verification; and provide sensitive proxies for environmental changes. As the global geosciences community continues to advance our understanding of Earth structure and processes controlling elastic wave propagation, GSN infrastructure offers a springboard to realize increasingly multi‐instrument geophysical observatories. Here, we review the historical, scientific, and monitoring heritage of GSNs, summarize key discoveries, and discuss future associated opportunities for Earth Science.