The World’s Largest Fouta Djallon–Mandingo Bauxite Province (West Africa): Part I. Background     

Mamedov  V. I.  Chausov  A. A.  Okonov  E. A.  Makarova  M. A.  Boeva  N. M. 《Geology of Ore Deposits》2020,62(2):163-176

Geology of Ore Deposits - The recognition of the Fouta Djallon–Mandingo territory as an independent bauxite province is substantiated. It is confined to the morphostructure of the same name...  相似文献   

Impact of COVID-19 Lockdown on Air Quality in Moscow     

Ginzburg  A. S.  Semenov  V. A.  Semutnikova  E. G.  Aleshina  M. A.  Zakharova  P. V.  Lezina  E. A. 《Doklady Earth Sciences》2020,495(1):862-866

Doklady Earth Sciences - The results of an analysis of changes in the atmospheric air quality in Moscow during the lockdown period and the decline in business activity caused by the COVID-19...  相似文献   

Root growth dynamics during recovery of tropical mountain forest in North-east India     

Chalthleng LALNUNZIRA  Francis Q.BREARLEY  Shri Kant TRIPATHI 《山地科学学报》2019,(10)

Ever increasing pressures on tropical forests worldwide due to anthropogenic disturbances have greatly affected both above-and belowground functioning of these forests.While fine roots play major ecological roles in forests through assisting in nutrient and water uptake and returning elements to the soil environment,coarse roots play an important role in C sequestration.We studied changes in fine and coarse root biomass,production,turnover and carbon and nitrogen return to the soil in two regenerating forest stands(RFs)following stonemining that were 5 years(RF-5)and 15 years(RF-15)post-disturbance compared with a natural forest stand(NF)in Mizoram,North-east India.Fine(2mm)and coarse root(2-10 mm)biomass differed significantly among the forest stands and ranged from239(RF-5)to 415(NF)and 230(RF-5)to 436(NF)g m 2,respectively.Total root(fine+coarse)biomass increased during stand development but the proportion of very fine root(0.5 mm)to total root production decreased.Fine root biomass decreased with increasing soil depth.Fine and total root biomass showed strong seasonal correlations with soil moisture,more so than for rainfall and temperature,whereas these relationships were less clear for the coarse root biomass.The amount of N(25-55 kg ha~(-1))and C(1.9-3.6t ha~(-1))stored in root biomass increased with stand age with a corresponding increase in production and turnover of C and N to the soil.Disturbance to these tropical forests negatively affected root dynamics,influenced their spatiotemporal patterns,and reduced the production,amount and availability of nutrients returned to the soil along with a strong reduction in the root biomass carbon pool and sequestration in carbon residence time.We observed that root growth,especially fine roots,is dependent on abiotic variables,and plays a significant role in early stages of secondary succession by adding organic matter and nutrients through high turnover rates in these forests.  相似文献   

Vulnerable groups and preliminary insights into intersecting categories of identity in Laamu Atoll,Maldives     

Karen E. McNamara  Rachel Clissold 《Singapore journal of tropical geography》2019,40(3):410-428

The notion of vulnerability has acquired a significant role in discussions around reducing risk and identifying vulnerable groups, which is particularly important for targeting risk‐reducing policy and practice. Through ten semi‐structured interviews with 24 stakeholders, this study collected local perceptions on the following groups considered most vulnerable in Laamu Atoll, Maldives: youth and children, women, the elderly, people with disabilities, displaced persons and migrants, and farmers. In doing this, the significance of intersecting categories of identity for understanding vulnerability emerged and was explored; an approach that is often absent or scarcely applied in studies that identify vulnerable groups in the Maldives and elsewhere. Intersections between location, youth and gender or disability, as well as gender and marital status emerged as relevant for the Laamu Atoll context. Although this study acknowledges the incompleteness of its intersectional analysis, these findings provide important preliminary insights into the role of intersectionality in shaping vulnerability experience. To enhance scholarship on vulnerability, future studies could further explore intersectionality in Laamu Atoll and the Maldives using this study as a base and also improve its practical applicability for policy and practice.  相似文献   

Petrography of Late Cambrian to Middle Ordovician radiolarian chert in Kazakhstan with special reference to the emergence of benthic animals in the pelagic realm     

Yoshitaka Kakuwa  Olga I. Nikitina 《Sedimentology》2020,67(5):2764-2776

Upper Cambrian to Middle Ordovician radiolarian chert successions from Kazakhstan were studied to clarify the history of the emergence of benthic animals in ocean floor sediments. Radiolarian tests and clay were deposited for a period of 30 Myr without experiencing an influx of continent-derived coarse clastic materials. Red, grey and black cherts of the Upper Cambrian to the upper mid-Darriwilian are thinly laminated, and no trace of benthic animal activity is recognized in that time interval. Bioturbation structures and burrow traces in mid-Darriwilian stage red chert in Kazakhstan suggest that benthic animals colonized the location where radiolarian chert formed, but that there was a significant delay in colonization when compared with similar reported occurrences in Australia and Canada.  相似文献   

Salt-induced crestal faults control the formation of Quaternary tunnel valleys in the southern North Sea     

Stefan Wenau  Tiago M. Alves 《Boreas: An International Journal of Quaternary Research》2020,49(4):799-812

Tunnel valleys are major features of glaciated margins and they enable meltwater expulsion from underneath a thick ice cover. Their formation is related to the erosion of subglacial sediments by overpressured meltwater and direct glacial erosion. Yet, the impact of pre-existing structures on their formation and morphology remains poorly known. High-quality 3D seismic data allowed the mapping of a large tunnel valley that eroded underlying preglacial delta deposits in the southern North Sea. The valley follows the N–S strike of crestal faults related to a Zechstein salt wall. A change in downstream tunnel valley orientation towards the SE accompanies a change in the strike direction of salt-induced faults. Fault offsets indicate important activity of crestal faults during the deposition of preglacial deltaic sediments. We propose that crestal faults facilitated tunnel valley erosion by acting as high-permeability pathways and allowing subglacial meltwater to reach low-permeability sediments in the underlying Neogene deltaic sequences, ultimately resulting in meltwater overpressure build-up and tunnel valley excavation. Active faults probably also weakened the near-surface sediment to allow a more efficient erosion of the glacial substrate. This control of substrate structures on tunnel valley morphology is considered as a primary factor in subglacial drainage pattern development in the study area.  相似文献   

New Circulation Features in the Okhotsk Sea from a Numerical Model     

Fayman  P. A.  Prants  S. V.  Budyansky  M. V.  Uleysky  M. Yu. 《Izvestiya Atmospheric and Oceanic Physics》2020,56(6):618-631

Izvestiya, Atmospheric and Oceanic Physics - Using the eddy-permitting model, circulation in the Okhotsk Sea and in an adjacent area of the Pacific Ocean is retrospectively simulated from 1991 to...  相似文献   

Algorithm for the Atmospheric Correction of Shortwave Channels of the MSU-MR Radiometer of the Meteor-M No. 2 Satellite     

Kuchma  M. O.  Bloshchinskiy  V. D. 《Izvestiya Atmospheric and Oceanic Physics》2020,56(9):909-915

Izvestiya, Atmospheric and Oceanic Physics - The problem of atmospheric correction for shortwave channels of a multispectral low-resolution scanning radiometer onboard the Meteor-M No. 2 satellite...  相似文献   

Traces of Seismic Activity in Architectural Monuments in Derbent,Dagestan     

Korzhenkov  A. M.  Gadzhiev  M. S.  Ovsyuchenko  A. N.  Lar’kov  A. S.  Rogozhin  E. A. 《Izvestiya Atmospheric and Oceanic Physics》2020,56(7):633-656

Izvestiya, Atmospheric and Oceanic Physics - As a result of studies conducted in the city of Derbent, it is established that its monumental fortification structures erected at the end of the 560s...  相似文献   

Earth’s Climate Does Not Depend on Variations in Cosmic Rays and Cloud Coverage     

Abdussamatov  H. I. 《Geomagnetism and Aeronomy》2019,59(7):935-941

Geomagnetism and Aeronomy - The hypothesis put forward by Svensmark and Friis-Christensen (1997), Svensmark (2007), Svensmark et al. (2017), and Stozhkov et al. (2017) assumes while completely...  相似文献