The onset,cessation,and length of the rainy season are crucial for global water resources,agricultural practices,and food security.However,the response of precipitation seasonality to global warming remains uncertain....The onset,cessation,and length of the rainy season are crucial for global water resources,agricultural practices,and food security.However,the response of precipitation seasonality to global warming remains uncertain.In this study,we analyze how global warming levels(GWLs)of 1.5℃ and 2℃ could affect the timing of rainfall onset(RODs),rainfall cessation(RCDs),and the overall duration of the rainy season(LRS)over global land monsoon(GLM)regions using simulations from CMIP6 under the SSP2-4.5 and SSP5-8.5 scenarios.With high model consensus,our results reveal that RODs are projected to occur later over Southern Africa,North Africa,and South America,but earlier over South Asia and Australia,in a warmer climate.The projected early RODs in Australia are more pronounced at the 2℃ GWL under SSP5-8.5.On the other hand,early RCDs are projected over South America and East Asia,while late RCDs are projected over North Africa,with high inter-model agreement.These changes are associated with a future decrease in LRS in most GLM regions.Additionally,we found that continuous warming over 1.5℃ will further reduce the length of the rainy season,especially over the South America,North Africa,and Southern Africa monsoon regions.The findings underscore the urgent need to mitigate global warming.展开更多
In recent years,there has been an increasing need for climate information across diverse sectors of society.This demand has arisen from the necessity to adapt to and mitigate the impacts of climate variability and cha...In recent years,there has been an increasing need for climate information across diverse sectors of society.This demand has arisen from the necessity to adapt to and mitigate the impacts of climate variability and change.Likewise,this period has seen a significant increase in our understanding of the physical processes and mechanisms that drive precipitation and its variability across different regions of Africa.By leveraging a large volume of climate model outputs,numerous studies have investigated the model representation of African precipitation as well as underlying physical processes.These studies have assessed whether the physical processes are well depicted and whether the models are fit for informing mitigation and adaptation strategies.This paper provides a review of the progress in precipitation simulation overAfrica in state-of-the-science climate models and discusses the major issues and challenges that remain.展开更多
This paper presents a prospective forecast of the locations of the next M_(W)≥6.5 earthquakes in California and Nevada based on the locations and rates of occurrence of M≥4.0 earthquakes during the past 30 years,cal...This paper presents a prospective forecast of the locations of the next M_(W)≥6.5 earthquakes in California and Nevada based on the locations and rates of occurrence of M≥4.0 earthquakes during the past 30 years,called here preshocks.The time period of the forecast is arbitrarily set at 33 years.The forecast faults are the Anza section of the San Jacinto Fault,the Calaveras Fault,the creeping section of the San Andreas Fault,the Maacama Fault,the San Bernardino section of the San Jacinto Fault,and the southern San Andreas Fault,all strike-slip faults in California,and the normal-faulting Wassuk Range Fault in Nevada.The suspected preshocks have occurred randomly along the expected future fault ruptures at rates of at least 0.5 events per year.The temporal history of preshocks for past M≥6.5 earthquakes in California do not indicate when the future mainshock will occur.Outside of California,preshock activity was observed before the 2016 M_(W)7.0 Kumamoto,Japan earthquake,the 2023 M_(W)7.8 Kahramanmaras,Türkiye earthquake,and the 2017 M_(W)6.5 Jiuzhaigou,China earthquake,all strikeslip events,as well as the 2008 M_(W)7.9 Wenchuan,China thrust earthquake.The two mainshocks in China had preshock rates less than 0.5 events per year.By publishing this spatial earthquake forecast,seismologists in the future can evaluate whether or not this forecast was a total success,a total failure,or a partial success.The probability of just one of the forecast events actually taking place during the forecast time period is less than 2%.展开更多
Monitoring the evolution of foreshocks can be a valuable way to analyze the nucleation process.Foreshocks accompanying moderate mainshocks have been recorded in the west of Yunnan Province,China.We obtain the earthqua...Monitoring the evolution of foreshocks can be a valuable way to analyze the nucleation process.Foreshocks accompanying moderate mainshocks have been recorded in the west of Yunnan Province,China.We obtain the earthquake catalog and source parameters of the 2016 Yunlong foreshocks,and discuss the implications for the nucleation processes of the earthquake in western Yunnan,China.By using the matched filter detection,we identify 343 foreshocks with a magnitude of -0.8-4.5,starting with a magnitude 1.0 foreshock approximately 3 months before the 2016 M_(S)5.1 Yunlong mainshock.The spatial distribution of foreshocks doesn’t show localization or directional migration towards the mainshock.Coulomb stress analysis suggests a positive stress perturbation at the mainshock nucleate area.These observations indicate a cascade-triggering mechanism of the 2016 Yunlong earthquakes.We further collect published catalogs of 2021 Yangbi and 2017 Yangbi foreshocks in the adjacent area,and analyze the temporal changes in b values.The temporal changes in b values reveal precursory drops before the mainshocks.展开更多
Many geological and geochemical changes are recorded on Earth between 3 and 2 Ga.Among the more important of these are the following:(1)increasing proportion of basalts with"arc-like"mantle sources;(2)an inc...Many geological and geochemical changes are recorded on Earth between 3 and 2 Ga.Among the more important of these are the following:(1)increasing proportion of basalts with"arc-like"mantle sources;(2)an increasing abundance of basalts derived from enriched(EM)and depleted(DM)mantle sources;(3)onset of a Great Thermal Divergence in the mantle;(4)a decrease in degree of melting of the mantle;(5)beginning of large lateral plate motions;(6)appearance of eclogite inclusions in diamonds;(7)appearance and rapid increase in frequency of collisional orogens;(8)rapid increase in the production rate of continental crust as recorded by zircon age peaks;(9)appearance of ophiolites in the geologic record,and(10)appearance of global LIP(large igneous province)events some of which correlate with global zircon age peaks.All of these changes may be tied directly or indirectly to cooling of Earth's mantle and corresponding changes in convective style and the strength of the lithosphere,and they may record the gradual onset and propagation of plate tectonics around the planet.To further understand the changes that occurred between 3 and 2 Ga,it is necessary to compare rocks,rock associations,tectonics and geochemistry during and between zircon age peaks.Geochemistry of peak and inter-peak basalts and TTGs needs to be evaluated in terms of geodynamic models that predict the existence of an episodic thermal regime between stagnant-lid and plate tectonic regimes in early planetary evolution.展开更多
The rare earth elements are unusual when defining giant-sized ore deposits,as resources are often quoted as total rare earth oxide,but the importance of a deposit may be related to the grade for individual,or a limite...The rare earth elements are unusual when defining giant-sized ore deposits,as resources are often quoted as total rare earth oxide,but the importance of a deposit may be related to the grade for individual,or a limited group of the elements.Taking the total REE resource,only one currently known deposit（Bayan Obo） would class as giant（〉1.7×10^7 tonnes contained metal）,but a range of others classify as large（〉1.7×10^6 tonnes）.With the exception of unclassified resource estimates from the Olympic Dam 10 CG deposit,all of these deposits are related to alkaline igneous activity- either carbonatites or agpaitic nepheline syenites.The total resource in these deposits must relate to the scale of the primary igneous source,but the grade is a complex function of igneous source,magmatic crystallisation,hydrothermal modification and supergene enrichment during weathering.Isotopic data suggest that the sources conducive to the formation of large REE deposits are developed in subcontinental lithospheric mantle,enriched in trace elements either by plume activity,or by previous subduction.The reactivation of such enriched mantle domains in relatively restricted geographical areas may have played a role in the formation of some of the largest deposits（e.g.Bayan Obo）.Hydrothermal activity involving fluids from magmatic to meteoric sources may result in the redistribution of the REE and increases in grade,depending on primary mineralogy and the availability of ligands.Weathering and supergene enrichment of carbonatite has played a role in the formation of the highest grade deposits at Mount Weld（Australia） and Tomtor（Russia）.For the individual REE with the current highest economic value（Nd and the HREE）,the boundaries for the large and giant size classes are two orders of magnitude lower,and deposits enriched in these metals（agpaitic systems,ion absorption deposits） may have significant economic impact in the near future.展开更多
The oldest Asian record of alpheid shrimps,assigned to genus Alpheus,based on snapping claw fingertips from the Miocene Khari Nadi Formation in the Kutch Basin,western India reported herein,extends the fossil record o...The oldest Asian record of alpheid shrimps,assigned to genus Alpheus,based on snapping claw fingertips from the Miocene Khari Nadi Formation in the Kutch Basin,western India reported herein,extends the fossil record of the family Alpheidae from Asia by~22 million years.An early Miocene(Aquitanian)age is estimated based on the associated assemblage of calcareous nannofossils,Sphenolithus disbelemnos,Cyclicargolithus floridanus,and Reticulofenestra haqii.The co-occurring microbiota includes bony fish otolith remains,identified as“genus Gobiidarum”,isolated teeth of Dasyatis rays,Sphyrna sharks,and teleosts,ctenoid and placoid scales,ostracods,belonging to the genera Paractinocythereis,Alocopocythere,Ruggieria,Aglaiocypris,Bairdoppilata,and echinoid spines.Taken together,the microfossil assemblage and data from chemical analyses using Energy Dispersive Spectroscopy,X-Ray Diffraction and Wavelength Dispersive X-Ray Fluorescence of host and associated lithologies suggests prevalence of a shallow(neritic)to coastal marine(intertidal)depositional paleoenvironment.The present investigation also provides the oldest fossil evidence on the co-occurrence of Alpheus and gobiids(based on otoliths)that strongly advocates that the mutualistic association between these animal groups had developed by the Aquitanian.展开更多
The July 2019 M_(W)6.4 Ridgecrest,California earthquake and its distinct foreshocks were well recorded by local and regional stations,providing a great opportunity to characterize its foreshocks and investigate the nu...The July 2019 M_(W)6.4 Ridgecrest,California earthquake and its distinct foreshocks were well recorded by local and regional stations,providing a great opportunity to characterize its foreshocks and investigate the nucleation mechanisms of the mainshock.In this study,we utilized the match-and-locate(M&L)method to build a high-precision foreshock catalog for this M_(W)6.4 earthquake.Compared with the sequential location methods(matched-filter+cross-correlation-based hypoDD),our new catalog contains more events with higher location accuracy.The M_(W)6.4 mainshock was preceded by 40 foreshocks within~2 h(on July 4,2019 from 15:35:29 to 17:32:52,UTC).Their spatiotemporal distribution revealed a complex seismogenic structure consisting of multiple fault strands,which were connected as a throughgoing fault by later foreshocks and eventually accommodated the 2019 M_(W)6.4 mainshock.To better understand the nucleation mechanism,we determined the rupture dimension of the largest M_(L)4.0 foreshock by calculating its initial rupture and centroid points using the M&L method.By estimating Coulomb stress change we suggested that the majority of foreshocks following the M_(L)4.0 event and M_(W)6.4 mainshock occurred within regions of increasing Coulomb stress,indicating that they were triggered by stress transfer.The nucleation process before the M_(L)4.0 event remains unclear due to the insufficient sampling rate of waveforms and small magnitude of events.Thus,our study demonstrates that the M&L method has superior detection and location ability,showing potential for studies that require high-precision location(e.g.,earthquake nucleation).展开更多
Droughts pose significant threats to forest ecosystems globally.Effective forest management strategies,adapted to local conditions,are needed to mitigate negative drought impacts.One proposed strategy is competition r...Droughts pose significant threats to forest ecosystems globally.Effective forest management strategies,adapted to local conditions,are needed to mitigate negative drought impacts.One proposed strategy is competition reduction to increase water availability and,as a result,alleviate drought stress.This study investigates the effect of competition intensity on drought stress and tree growth in European beech(Fagus sylvatica)and pedunculate oak(Quercus robur).We deployed 72 point dendrometers,placed along a competition intensity gradient,in National Park Brabantse Wouden(Belgium),to measure daily minimum tree water deficit(TWD_(min))as a drought stress proxy and daily radial growth at tree level.Our results revealed species-dependent effects of competition intensity(CI).For European beech,competition reductions positively influenced growth and alleviated(1<CI<2)or aggravated(CI<0.5)drought stress.For pedunculate oak,competition intensity did not affect drought stress or growth along the investigated gradient.Environmental variables consistently affected TWDmin and growth of both species.Precipitation reduced TWDmin and increased growth,while vapor pressure deficit led to opposite trends.Thus,environmental conditions and competition can play a critical role in forest dynamics,especially in light of climate change.However,reducing competition through increased management efforts does not seem to be a one-size-fits-all solution to alleviating drought stress.Additionally,there seems to be a trade-off between reducing drought stress and improving tree growth in European beech:tree growth continuously benefited from competition reductions,while under low competition(CI<0.5)drought stress increased.Revisiting or reviving long-term thinning intensity trials encompassing various regions,species,and soil types will be needed to gain comprehensive insights into mitigating drought stress through management interventions under different local stand conditions.展开更多
Mantle plumes and surface erosion and sediment deposition affect the modes of continental lithospheric rupturing in extensional tectonic settings,modulating the evolution of rifting margins.However,their relative cont...Mantle plumes and surface erosion and sediment deposition affect the modes of continental lithospheric rupturing in extensional tectonic settings,modulating the evolution of rifting margins.However,their relative contributions to the overall evolution of rifting margins and possible roles in the formation of microcontinent are still elusive.Here,we use coupled geodynamic and surface processes numerical modeling to assess the extent to which surface processes may determine the formation of microcontinent during lithospheric stretching in presence or absence of a mantle plume underneath.Our modeling results indicate that fast extension rates and hillslope(i.e.,diffusion)erosion promote ridge jump events and therefore the formation of microcontinents.On the contrary,efficient fluvial erosion and far-reaching sediment transport(i.e.,stream power erosion)inhibits ridge jump events and the formation of microcontinents.The ridge jump event and overall evolution in our numerical models is consistent with the shift from the Mascarene Ridge to the Carlsberg Ridge that determined the formation of the Seychelles microcontinent.We therefore speculate that hillslope erosion,rather than fluvial erosion,was predominant during the formation of the Seychelles,a possible indication of overall dry local climate conditions.展开更多
To study the energy evolution and failure characteristics of saturated sandstone under unloading conditions,rock unloading tests under different stress paths were conducted.The energy evolution mechanism of the unload...To study the energy evolution and failure characteristics of saturated sandstone under unloading conditions,rock unloading tests under different stress paths were conducted.The energy evolution mechanism of the unloading failure of saturated sandstone was systematically explored from the perspectives of the stress path,the initial confining pressure,and the energy conversion rate.The results show that(1)before the peak stress,the elastic energy increases with an increase in deviatoric stress,while the dissipated energy slowly increases first.After the peak stress,the elastic energy decreases with the decrease of deviatoric stress,and the dissipated energy suddenly increases.The energy release intensity during rock failure is positively correlated with the axial stress.(2)When the initial confining pressure is below a certain threshold,the stress path is the main factor influencing the total energy difference.When the axial stress remains constant and the confining pressure is unloading,the total energy is more sensitive to changes in the confining pressure.When the axial stress remains constant,the compressive deformation ability of the rock cannot be significantly improved by the increase in the initial confining pressure.The initial confining pressure is positively correlated with the rock's energy storage limit.(3)The initial confining pressure increases the energy conversion rate of the rock;the initial confining pressure is positively correlated with the energy conversion rate;and the energy conversion rate has a high confining pressure effect.The increase in the axial stress has a much greater impact on the elastic energy than the confining pressure.(4)When the deviatoric stress is small,the confining pressure mainly plays a protective role.Compared with the case of triaxial compression paths,the rock damage is more severe under unloading paths,and compared with the case of constant axial stress,the rock damage is more severe under increasing axial stress.展开更多
Detrital zircon geochronology is reported from the c.1200 m thick Cambro-Ordovician sedimentary succession recovered in core from the COSC-2 continental drilling project in the Scandinavian Caledonides.Above a regolit...Detrital zircon geochronology is reported from the c.1200 m thick Cambro-Ordovician sedimentary succession recovered in core from the COSC-2 continental drilling project in the Scandinavian Caledonides.Above a regolith marking the sub-Cambrian peneplain,a lower to middle Cambrian(?)succession comprises conglomerate,sandstone and shale overlain by gravity flows fining upwards into the Alum Shale Formation.First results of detrital zircon geochronology from the Cambrian(?)succession show that the basal section of the autochthonous cover is characterized by mainly late Paleoproterozoic–early Mesoproterozoic detrital grains.The middle part of the succession is dominated by late Paleoproterozoic detritus with minor Mesoproterozoic and Archean input.The upper part of lower Cambrian(?)succession is characterized by Archean to Cambrian detritus.The maximum depositional age is calculated to 530.5±4 Ma for the upper part of the lower Cambrian succession.Two samples from the Lower Ordovician(?)succession above the Alum Shale Formation show predominantly Mesoproterozoic to early Neoproterozoic(1.5–0.9 Ga)ages.The autochthonous lower Cambrian(?)passive margin succession in the lower section is dominated by local detritus,sourced exclusively from the Eastern Segment of the Sveconorwegian Orogen,which includes the basement studied in COSC-2.Up-section,the provenance shifts towards the Transscandinavian Igneous Belt and Svecofennian Orogen sources,with the youngest part of the succession showing a notable input of Neoproterozoic–Cambrian active margin detritus.The Ordovician(?)succession is characterized by populations,likely derived from the Sveconorwegian Orogen,and a minor cratonic contribution.Statistical analysis of detrital zircon datasets across Baltica suggests that the Southern Baltica/Sandomirian Arc,rather than the Timanian Orogen,was a significant source of detrital material across the paleocontinent.The influence of Timanian Orogen grains is limited to northernmost Scandinavia,whereas Sandomirian detritus reached central Scandinavia in the lower to middle Cambrian and remained prevalent in southern Scandinavia into the Lower Ordovician.展开更多
Determining the rupture directivity for small earthquakes is challenging due to the small source dimension and limited resolution of far-field observations.In recent years,the burst of near-source observations provide...Determining the rupture directivity for small earthquakes is challenging due to the small source dimension and limited resolution of far-field observations.In recent years,the burst of near-source observations provides great opportunities to study earthquake rupture.Here we present the rapid determination of the rupture directivity for the 2024 Feidong M4.7 earthquake using only one strong motion station located 4 km from the epicenter.We find that the polarization of S waves evolves during the rupture,indicating an azimuth change during the rupture propagation.Through comparing the data with the synthetic waveforms,we infer that the M4.7 event propagated dominantly to the southwest on the dextral Tanlu fault.Our inference is further validated through comparing the data with records at local stations for M3 earthquakes in the Feidong sequence.Our study highlights the superior application of near-source observations in earthquake source studies.展开更多
Surface ozone(O_(3))pollution showed a continuous increasing trend during the recent decades in China,posing an increasing threat to food security.A wide range of yield reductions have been reported and thus more stud...Surface ozone(O_(3))pollution showed a continuous increasing trend during the recent decades in China,posing an increasing threat to food security.A wide range of yield reductions have been reported and thus more studies are needed to narrow down the uncertainty resulting from spatiotemporal accuracy of O_(3) metrics and extrapolation methods.Based on a high spatial resolution(0.1°)hourly surface O_(3) data,here we analyzed the spatiotemporal O_(3) pollution patterns and impacts on yield,production and economic losses for wheat,rice,and maize in China during 2005–2020.The accumulated O_(3) exposure over a threshold of 40 ppb(AOT40)increased by 10%during 2005–2019,and a decrease of 5.56%was observed in 2020 due to the COVID-19 lockdowns.Rising O_(3) pollution reduced national level wheat,rice and maize yields by 14.51%±0.43%,11.10%±0.6%,and 3.99%±0.11%,respectively.A Business-As-Usual projection suggested that the relative yield loss(RYL)would potentially reach 8%–18%at the national scale by 2050 if no emission control is implemented.COVID-19 lockdowns in 2020 led to significantly reduced RYL for maize(0.52%)and rice(2.17%)but not for wheat(0.11%),with the largest reduction(1.88%–9.4%)in North China Plain,highlighting the potential benefits of emission control.Our findings provided robust evidence that rising O_(3) pollution has significantly affected China’s crop yields,production and economic losses,underscoring the urgent need to curb O_(3) pollution to safeguard food security,particularly in densely populated and industrialized regions.展开更多
The semi-arid mangroves of the Gulf of Kachchh,the largest ecosystems on the west coast of India,are poorly studied in terms of vegetation structure and environmental parameters in spite of their conservation signific...The semi-arid mangroves of the Gulf of Kachchh,the largest ecosystems on the west coast of India,are poorly studied in terms of vegetation structure and environmental parameters in spite of their conservation significance.Therefore,it is necessary to document the structural features of these mangroves in view of ongoing coastal industrial development.Mangrove forest structure in 10 locations on the northern and southern coasts of the Gulf of Kachchh were assessed using the line intercept transect method.Descriptions included density of young and mature age classes,tree heights,diameters at breast height(DBH)and aboveground biomass,along with seven significant environmental variables.Mature tree densities ranged from 350 to 1567 ind.ha-1,while average height and girth at breast height ranged from 1.0 to 6.8 m and 3.0 to 137.0 cm,respectively.The majority of trees(55.6%)were in B 1.8 m height class followed by a 1.9 to 2.4 m class(25.1%).DBH was most often in class 2 cm or lower than that.Among the canopy index classes,more trees were recorded in class ≤2 cm.The regeneration density was greater than the recruitment class.This study indicates that the poor structural attributes of Avicennia marina Vierth.var.acutissima Stapf and Mold dominated mangroves are largely due to aridity induced by scarce and erratic rainfall and high soil and water salinities.The results should be valuable in conserving and sustainably managing these mangroves in the face of developmental activities.展开更多
Covered by ultrabasic units for more than a third of its surface,the New Caledonia(South West Pacific)is one of the largest world producers of Ni-ore from lateritic deposits.Almost all outcrops of geological units and...Covered by ultrabasic units for more than a third of its surface,the New Caledonia(South West Pacific)is one of the largest world producers of Ni-ore from lateritic deposits.Almost all outcrops of geological units and open mines contain serpentine and amphibole,also as asbestos varieties.In this geological context,in which weathering processes had a great contribution in the production and dispersion of mineral fibres into the environment,the development of a routinely analytical strategy,able to discriminate an asbestiform fibre from a non-harmful particle,is a pivotal requisite.However,the acquisition of all these parameters is necessary for determining the risk associated to fibres exposition.A multidisciplinary routinely approach,based on the use of complementary simply-to-use but reliable analytical methods is the only possible strategy.In addition,the instrumental apparatus must be easily transportable on the field,directly on the mining site.The employment of specialized tools such as Polarized Light Microscopy associated to Dispersion Staining method(PLM/DS)and portable Raman spectroscopy for identification of environmental asbestos,are proved extremely effective in the improvement of the performance and rapidity of data acquisition and interpretation.Both PLM/DS and handheld Raman devices confirmed to be discriminant in the detection and characterization of asbestos fibres for both serpentine and amphibole.Furthermore,these techniques proved extremely effective even in the presence of strongly fibrous and altered samples.展开更多
The Urban Commune of Maradi in Niger experienced increasingly frequent flooding following rainy episodes generating volumes and water flows that are difficult to control in recent years. This study aims to determine t...The Urban Commune of Maradi in Niger experienced increasingly frequent flooding following rainy episodes generating volumes and water flows that are difficult to control in recent years. This study aims to determine the impacts of runoff water in Commune II of Maradi City and to assess the role of urban planning in runoff management, as well as the strengths and weaknesses of urban sanitation in Maradi. The methodological approach used consisted of: 1) an interpretation of documentary data, 2) gathering information on runoff at several sites in the study area, and 3) interviews and questionnaires with local communities. This approach made it possible to understand the degree of vulnerability of the populations to flooding and then to propose sustainable solutions to reduce the vulnerability of the affected populations, through the implementation of effective urban rainwater management practices (USWMP). The results show that the impacts of runoff are mainly related to the lack of adequate storm water drainage networks in the area, but also to the nature of the habitats. Geomorphological factors such as the nature of the soil, the slope of the terrain and the altitude increase the degree of risk. In addition, the inadequacy and dilapidation of the drainage systems of the canals and above all the anarchic occupation of the land linked to accelerated urbanization are the cause of flooding by stagnation of rainwater. A phenomenon now linked to numerous deteriorations of urban equipment, the runoff of rainwater in the city of Maradi carries so many pollutants that municipalities, businesses and individuals should put in place pollution prevention measures.展开更多
Introduction:Pharmaceuticals are regarded as emerging contaminants in the environment.In recent years,their destiny and removal have piqued people’s interest.Methods:Examine how well conventional wastewater treatment...Introduction:Pharmaceuticals are regarded as emerging contaminants in the environment.In recent years,their destiny and removal have piqued people’s interest.Methods:Examine how well conventional wastewater treatment facilities and cutting-edge technologies(ultrafiltration and reverse osmosis)can remove specific pharmaceutical compounds from water,with a focus on the compounds'environmental status,their origin,deterioration,metabolites,and the capacities of these facilities.Results and discussion:the ability and efficacy of sophisticated treatment technologies such as membrane separation,adsorption,and AOPs(Advanced Oxidation Processes)in eliminating chosen commonly used drugs from water are explored.Batch adsorption experiments were integrated with appropriate adsorption isotherms and appropriate kinetic models to predict the final extent of pollutant removal by this method.Continuous filtration mode was also investigated.Combining filtration(using AC(Activated Carbon)and micelle-clay granule complexes)with AOPs improves the economy of treating wastewater,which contains recalcitrant PhACs(Pharmaceutical Compounds).展开更多
U–Pb analysis of zircons from igneous rocks in the Elashan Mountain,easternmost segment of the East Kunlun Orogen yielded 252–232 Ma.Geochemically,these rocks are mainly high in SiO_(2),K_2O and K_2O+Na_2O contents,...U–Pb analysis of zircons from igneous rocks in the Elashan Mountain,easternmost segment of the East Kunlun Orogen yielded 252–232 Ma.Geochemically,these rocks are mainly high in SiO_(2),K_2O and K_2O+Na_2O contents,low in P_2O_5 and TiO_(2) contents,depleted in Ba,Sr,P,Ti and enriched in U,Hf,Zr,showing features of I–type granite.The zirconεHf(t)values of the Early Triassic Jiamuge'er rhyolite porphyry(252±3 Ma)are positive(+1.6 to+12.1),suggesting a juvenile crustal source mixing with little old crustal component,and the zirconεHf(t)values of the Middle Triassic Manzhang'gang granodiorite(244±3 Ma)and Dehailong diorite(237±3 Ma)are predominately negative(-8.4 to+1.0),indicating an older crustal source.In comparison,the zirconεHf(t)values of the Late Triassic syenogranites from Suigen'ergang(234±2Ma),Ge'ermugang(233±2 Ma)and Yue'ergen(232±3 Ma)plutons vary from-3.8 to+5.0,suggesting a crust-mantle mixing source.From Early–Middle Triassic(252–237 Ma)to Late Triassic(234–232 Ma),the geochemical characteristics of these rocks show the change from a subduction–collision setting to a post-collision or within-plate setting.By comparing of these new age data with 77 zircon U–Pb ages of igneous rocks of the eastern part of East Kunlun orogen from published literatures,we conclude that the igneous rocks of Elashan Mountain and these of the eastern part of East Kunlun Orogen belong to one magmatic belt.All these data indicate that the Triassic magmatic events of the eastern part of East Kunlun Orogen can be divided into three stages:252–238 Ma,238–226 Ma and 226–212 Ma.Statistically,the averageεHf(t)values of the threestage igneous rocks show a tendency,from the old to young,from-0.75±0.25 to lower-2.65±0.52 and then to-1.22±0.25,respectively,which reveal the change of their sources.These characteristics can be explained as a crust-mantle mixing source generated in a subductional stage,mainly crust source in a syn–collisional stage and a crust-mantle mixing source(lower crust with mantle-derived underplating magma)in a post-collisional stage.The identification of these three magmatic events in the Elashan Mountain,including all the eastern part of East Kunlun Orogen,provides new evidence for better understanding of the tectonic evolution of the northward subduction and closure of the Paleo-Tethyan(252–238 Ma),the collision of the Songpan–Ganzi block with the southern margin of Qaidam block(238–226 Ma),and the post–collisional setting(226–212 Ma)during the Early Mesozoic period.展开更多
Pore structure characteristics of rock are a great concern for researchers and practitioners in rock mechanics and rock engineering fields. In this study, mercury intrusion porosimetry（MIP） was used to measure pore ...Pore structure characteristics of rock are a great concern for researchers and practitioners in rock mechanics and rock engineering fields. In this study, mercury intrusion porosimetry（MIP） was used to measure pore size distribution, as well as several important index parameters of pore structure, for seven common types of deep sedimentary rocks with a total of fifty rock samples. Results show a similar pore size distribution pattern of the rock samples in the same lithological group, but remarkable differences among different lithological groups. Among seven investigated rock types, mudstone has the smallest porosity of 3.37%, while conglomerate has the largest value of 18.8%. It is also found that the porosity of rock types with finer grain size is lower than those with coarser grain size. Meanwhile, a comparison of frequency distribution at ten intervals of pore-throat diameter among seven types of sedimentary rocks reveals that different rock types have different dominant pore-size ranges. Furthermore, permeability of the investigated sedimentary rock samples was derived based on MIP data using reported theoretical equations. Among seven rock types, mudstone has the lowest averaged permeability（3.64×10^（-6） mD） while conglomerate has the highest one（8.59×10^（-4） mD）. From mudstone to conglomerate, rock permeability increases with an increase of grain size, with only an exception of siltstone which has a relatively larger porosity value. Finally, regression analysis show that there is a good fitting（R^2=0.95） between permeability and porosity which could be easily used to derive reliable permeability values of similar kinds of engineering rocks.展开更多
基金supported by the Australian Research Council(Grant No.CE230100012)。
文摘The onset,cessation,and length of the rainy season are crucial for global water resources,agricultural practices,and food security.However,the response of precipitation seasonality to global warming remains uncertain.In this study,we analyze how global warming levels(GWLs)of 1.5℃ and 2℃ could affect the timing of rainfall onset(RODs),rainfall cessation(RCDs),and the overall duration of the rainy season(LRS)over global land monsoon(GLM)regions using simulations from CMIP6 under the SSP2-4.5 and SSP5-8.5 scenarios.With high model consensus,our results reveal that RODs are projected to occur later over Southern Africa,North Africa,and South America,but earlier over South Asia and Australia,in a warmer climate.The projected early RODs in Australia are more pronounced at the 2℃ GWL under SSP5-8.5.On the other hand,early RCDs are projected over South America and East Asia,while late RCDs are projected over North Africa,with high inter-model agreement.These changes are associated with a future decrease in LRS in most GLM regions.Additionally,we found that continuous warming over 1.5℃ will further reduce the length of the rainy season,especially over the South America,North Africa,and Southern Africa monsoon regions.The findings underscore the urgent need to mitigate global warming.
基金the World Climate Research Programme(WCRP),Climate Variability and Predictability(CLIVAR),and Global Energy and Water Exchanges(GEWEX)for facilitating the coordination of African monsoon researchsupport from the Center for Earth System Modeling,Analysis,and Data at the Pennsylvania State Universitythe support of the Office of Science of the U.S.Department of Energy Biological and Environmental Research as part of the Regional&Global Model Analysis(RGMA)program area。
文摘In recent years,there has been an increasing need for climate information across diverse sectors of society.This demand has arisen from the necessity to adapt to and mitigate the impacts of climate variability and change.Likewise,this period has seen a significant increase in our understanding of the physical processes and mechanisms that drive precipitation and its variability across different regions of Africa.By leveraging a large volume of climate model outputs,numerous studies have investigated the model representation of African precipitation as well as underlying physical processes.These studies have assessed whether the physical processes are well depicted and whether the models are fit for informing mitigation and adaptation strategies.This paper provides a review of the progress in precipitation simulation overAfrica in state-of-the-science climate models and discusses the major issues and challenges that remain.
文摘This paper presents a prospective forecast of the locations of the next M_(W)≥6.5 earthquakes in California and Nevada based on the locations and rates of occurrence of M≥4.0 earthquakes during the past 30 years,called here preshocks.The time period of the forecast is arbitrarily set at 33 years.The forecast faults are the Anza section of the San Jacinto Fault,the Calaveras Fault,the creeping section of the San Andreas Fault,the Maacama Fault,the San Bernardino section of the San Jacinto Fault,and the southern San Andreas Fault,all strike-slip faults in California,and the normal-faulting Wassuk Range Fault in Nevada.The suspected preshocks have occurred randomly along the expected future fault ruptures at rates of at least 0.5 events per year.The temporal history of preshocks for past M≥6.5 earthquakes in California do not indicate when the future mainshock will occur.Outside of California,preshock activity was observed before the 2016 M_(W)7.0 Kumamoto,Japan earthquake,the 2023 M_(W)7.8 Kahramanmaras,Türkiye earthquake,and the 2017 M_(W)6.5 Jiuzhaigou,China earthquake,all strikeslip events,as well as the 2008 M_(W)7.9 Wenchuan,China thrust earthquake.The two mainshocks in China had preshock rates less than 0.5 events per year.By publishing this spatial earthquake forecast,seismologists in the future can evaluate whether or not this forecast was a total success,a total failure,or a partial success.The probability of just one of the forecast events actually taking place during the forecast time period is less than 2%.
基金supported by the Laoshan Laboratory project(LSKJ202204100)National Natural Science Foundation of China(Nos.U2344221,92158205,42406064)+2 种基金Hong Kong Research Grant Council Grants(14306122)the Taishan Scholar Foundation of Shandong Province(tstp20230638)Shandong Province Outstanding Youth Science Fund Project Overseas(2023HWYQ-099).
文摘Monitoring the evolution of foreshocks can be a valuable way to analyze the nucleation process.Foreshocks accompanying moderate mainshocks have been recorded in the west of Yunnan Province,China.We obtain the earthquake catalog and source parameters of the 2016 Yunlong foreshocks,and discuss the implications for the nucleation processes of the earthquake in western Yunnan,China.By using the matched filter detection,we identify 343 foreshocks with a magnitude of -0.8-4.5,starting with a magnitude 1.0 foreshock approximately 3 months before the 2016 M_(S)5.1 Yunlong mainshock.The spatial distribution of foreshocks doesn’t show localization or directional migration towards the mainshock.Coulomb stress analysis suggests a positive stress perturbation at the mainshock nucleate area.These observations indicate a cascade-triggering mechanism of the 2016 Yunlong earthquakes.We further collect published catalogs of 2021 Yangbi and 2017 Yangbi foreshocks in the adjacent area,and analyze the temporal changes in b values.The temporal changes in b values reveal precursory drops before the mainshocks.
文摘Many geological and geochemical changes are recorded on Earth between 3 and 2 Ga.Among the more important of these are the following:(1)increasing proportion of basalts with"arc-like"mantle sources;(2)an increasing abundance of basalts derived from enriched(EM)and depleted(DM)mantle sources;(3)onset of a Great Thermal Divergence in the mantle;(4)a decrease in degree of melting of the mantle;(5)beginning of large lateral plate motions;(6)appearance of eclogite inclusions in diamonds;(7)appearance and rapid increase in frequency of collisional orogens;(8)rapid increase in the production rate of continental crust as recorded by zircon age peaks;(9)appearance of ophiolites in the geologic record,and(10)appearance of global LIP(large igneous province)events some of which correlate with global zircon age peaks.All of these changes may be tied directly or indirectly to cooling of Earth's mantle and corresponding changes in convective style and the strength of the lithosphere,and they may record the gradual onset and propagation of plate tectonics around the planet.To further understand the changes that occurred between 3 and 2 Ga,it is necessary to compare rocks,rock associations,tectonics and geochemistry during and between zircon age peaks.Geochemistry of peak and inter-peak basalts and TTGs needs to be evaluated in terms of geodynamic models that predict the existence of an episodic thermal regime between stagnant-lid and plate tectonic regimes in early planetary evolution.
基金the support of the NERC SoS:RARE consortium grant(NE/ M011267/1)the support of a postgraduate fellowship from the College of Engineering,Mathematics and Physical Sciences at the University of Exeter
文摘The rare earth elements are unusual when defining giant-sized ore deposits,as resources are often quoted as total rare earth oxide,but the importance of a deposit may be related to the grade for individual,or a limited group of the elements.Taking the total REE resource,only one currently known deposit（Bayan Obo） would class as giant（〉1.7×10^7 tonnes contained metal）,but a range of others classify as large（〉1.7×10^6 tonnes）.With the exception of unclassified resource estimates from the Olympic Dam 10 CG deposit,all of these deposits are related to alkaline igneous activity- either carbonatites or agpaitic nepheline syenites.The total resource in these deposits must relate to the scale of the primary igneous source,but the grade is a complex function of igneous source,magmatic crystallisation,hydrothermal modification and supergene enrichment during weathering.Isotopic data suggest that the sources conducive to the formation of large REE deposits are developed in subcontinental lithospheric mantle,enriched in trace elements either by plume activity,or by previous subduction.The reactivation of such enriched mantle domains in relatively restricted geographical areas may have played a role in the formation of some of the largest deposits（e.g.Bayan Obo）.Hydrothermal activity involving fluids from magmatic to meteoric sources may result in the redistribution of the REE and increases in grade,depending on primary mineralogy and the availability of ligands.Weathering and supergene enrichment of carbonatite has played a role in the formation of the highest grade deposits at Mount Weld（Australia） and Tomtor（Russia）.For the individual REE with the current highest economic value（Nd and the HREE）,the boundaries for the large and giant size classes are two orders of magnitude lower,and deposits enriched in these metals（agpaitic systems,ion absorption deposits） may have significant economic impact in the near future.
基金granted by the BSIP LucknowIndia in the form of an In-house Project No. 3 (2021–2025)
文摘The oldest Asian record of alpheid shrimps,assigned to genus Alpheus,based on snapping claw fingertips from the Miocene Khari Nadi Formation in the Kutch Basin,western India reported herein,extends the fossil record of the family Alpheidae from Asia by~22 million years.An early Miocene(Aquitanian)age is estimated based on the associated assemblage of calcareous nannofossils,Sphenolithus disbelemnos,Cyclicargolithus floridanus,and Reticulofenestra haqii.The co-occurring microbiota includes bony fish otolith remains,identified as“genus Gobiidarum”,isolated teeth of Dasyatis rays,Sphyrna sharks,and teleosts,ctenoid and placoid scales,ostracods,belonging to the genera Paractinocythereis,Alocopocythere,Ruggieria,Aglaiocypris,Bairdoppilata,and echinoid spines.Taken together,the microfossil assemblage and data from chemical analyses using Energy Dispersive Spectroscopy,X-Ray Diffraction and Wavelength Dispersive X-Ray Fluorescence of host and associated lithologies suggests prevalence of a shallow(neritic)to coastal marine(intertidal)depositional paleoenvironment.The present investigation also provides the oldest fossil evidence on the co-occurrence of Alpheus and gobiids(based on otoliths)that strongly advocates that the mutualistic association between these animal groups had developed by the Aquitanian.
基金This work was co-supported by the National Natural Science Foundation of China(Nos.U1939203 and 41874063)China Earthquake Science Experiment project,China Earthquake Administration(No.2019CSES0113)+2 种基金the Fundamental Research Funds for the Central Universities of China(2-9-2019-172)Engineering Research Council of Canada Discovery Grant(RGPIN-2019-04297)the Ocean Frontier Institute International Postdoctoral Program.
文摘The July 2019 M_(W)6.4 Ridgecrest,California earthquake and its distinct foreshocks were well recorded by local and regional stations,providing a great opportunity to characterize its foreshocks and investigate the nucleation mechanisms of the mainshock.In this study,we utilized the match-and-locate(M&L)method to build a high-precision foreshock catalog for this M_(W)6.4 earthquake.Compared with the sequential location methods(matched-filter+cross-correlation-based hypoDD),our new catalog contains more events with higher location accuracy.The M_(W)6.4 mainshock was preceded by 40 foreshocks within~2 h(on July 4,2019 from 15:35:29 to 17:32:52,UTC).Their spatiotemporal distribution revealed a complex seismogenic structure consisting of multiple fault strands,which were connected as a throughgoing fault by later foreshocks and eventually accommodated the 2019 M_(W)6.4 mainshock.To better understand the nucleation mechanism,we determined the rupture dimension of the largest M_(L)4.0 foreshock by calculating its initial rupture and centroid points using the M&L method.By estimating Coulomb stress change we suggested that the majority of foreshocks following the M_(L)4.0 event and M_(W)6.4 mainshock occurred within regions of increasing Coulomb stress,indicating that they were triggered by stress transfer.The nucleation process before the M_(L)4.0 event remains unclear due to the insufficient sampling rate of waveforms and small magnitude of events.Thus,our study demonstrates that the M&L method has superior detection and location ability,showing potential for studies that require high-precision location(e.g.,earthquake nucleation).
基金supported by the Fonds Wetenschappelijk Onderzoek(FWO)[grant number 1S16824N]the Cost Action CLEANFOREST[E-COST-GRANT-CA21138-c4968ca1].
文摘Droughts pose significant threats to forest ecosystems globally.Effective forest management strategies,adapted to local conditions,are needed to mitigate negative drought impacts.One proposed strategy is competition reduction to increase water availability and,as a result,alleviate drought stress.This study investigates the effect of competition intensity on drought stress and tree growth in European beech(Fagus sylvatica)and pedunculate oak(Quercus robur).We deployed 72 point dendrometers,placed along a competition intensity gradient,in National Park Brabantse Wouden(Belgium),to measure daily minimum tree water deficit(TWD_(min))as a drought stress proxy and daily radial growth at tree level.Our results revealed species-dependent effects of competition intensity(CI).For European beech,competition reductions positively influenced growth and alleviated(1<CI<2)or aggravated(CI<0.5)drought stress.For pedunculate oak,competition intensity did not affect drought stress or growth along the investigated gradient.Environmental variables consistently affected TWDmin and growth of both species.Precipitation reduced TWDmin and increased growth,while vapor pressure deficit led to opposite trends.Thus,environmental conditions and competition can play a critical role in forest dynamics,especially in light of climate change.However,reducing competition through increased management efforts does not seem to be a one-size-fits-all solution to alleviating drought stress.Additionally,there seems to be a trade-off between reducing drought stress and improving tree growth in European beech:tree growth continuously benefited from competition reductions,while under low competition(CI<0.5)drought stress increased.Revisiting or reviving long-term thinning intensity trials encompassing various regions,species,and soil types will be needed to gain comprehensive insights into mitigating drought stress through management interventions under different local stand conditions.
基金financially supported by the National Science Foundation of China(No.41920104010)the China Postdoctoral Science Foundation(No.2024M762767)+3 种基金the Fundamental Research Funds for the Central University,CHD(No.300102264104)by the Postdoctoral Fellowship Program of CPSF(No.GZC20241444)supported by Fondazione Cariplo and Fondazione CDP(No.2022-1546_001)by the Italian Ministry of Education,MUR(Project Dipartimenti di Eccellenza,TECLA,Department of Earth and Environmental Sciences,University of Milano-Bicocca)。
文摘Mantle plumes and surface erosion and sediment deposition affect the modes of continental lithospheric rupturing in extensional tectonic settings,modulating the evolution of rifting margins.However,their relative contributions to the overall evolution of rifting margins and possible roles in the formation of microcontinent are still elusive.Here,we use coupled geodynamic and surface processes numerical modeling to assess the extent to which surface processes may determine the formation of microcontinent during lithospheric stretching in presence or absence of a mantle plume underneath.Our modeling results indicate that fast extension rates and hillslope(i.e.,diffusion)erosion promote ridge jump events and therefore the formation of microcontinents.On the contrary,efficient fluvial erosion and far-reaching sediment transport(i.e.,stream power erosion)inhibits ridge jump events and the formation of microcontinents.The ridge jump event and overall evolution in our numerical models is consistent with the shift from the Mascarene Ridge to the Carlsberg Ridge that determined the formation of the Seychelles microcontinent.We therefore speculate that hillslope erosion,rather than fluvial erosion,was predominant during the formation of the Seychelles,a possible indication of overall dry local climate conditions.
基金Anhui Natural Science Foundation Youth Program,Grant/Award Number:2208085QE142National Natural Science Foundations of China,Grant/Award Numbers:52004003,52304073Opening Foundation of Anhui Province Key Laboratory of Building Structure and Underground Engineering,Grant/Award Number:KLBSUE-2022-04。
文摘To study the energy evolution and failure characteristics of saturated sandstone under unloading conditions,rock unloading tests under different stress paths were conducted.The energy evolution mechanism of the unloading failure of saturated sandstone was systematically explored from the perspectives of the stress path,the initial confining pressure,and the energy conversion rate.The results show that(1)before the peak stress,the elastic energy increases with an increase in deviatoric stress,while the dissipated energy slowly increases first.After the peak stress,the elastic energy decreases with the decrease of deviatoric stress,and the dissipated energy suddenly increases.The energy release intensity during rock failure is positively correlated with the axial stress.(2)When the initial confining pressure is below a certain threshold,the stress path is the main factor influencing the total energy difference.When the axial stress remains constant and the confining pressure is unloading,the total energy is more sensitive to changes in the confining pressure.When the axial stress remains constant,the compressive deformation ability of the rock cannot be significantly improved by the increase in the initial confining pressure.The initial confining pressure is positively correlated with the rock's energy storage limit.(3)The initial confining pressure increases the energy conversion rate of the rock;the initial confining pressure is positively correlated with the energy conversion rate;and the energy conversion rate has a high confining pressure effect.The increase in the axial stress has a much greater impact on the elastic energy than the confining pressure.(4)When the deviatoric stress is small,the confining pressure mainly plays a protective role.Compared with the case of triaxial compression paths,the rock damage is more severe under unloading paths,and compared with the case of constant axial stress,the rock damage is more severe under increasing axial stress.
基金funded by the National Science Centre(NCN,Poland)project nos.2018/29/B/ST10/02315 and 2019/33/B/ST10/01728 and the Swedish Research Council(Vetenskapsrådet)grant no.2019-03688.OL is grateful to the Deutsche Forschunggemeinschaft for the support of his COSC-2 research(DFG 867/12-1,13-1,and 13-2)supported by a National Science Foundation(USA)grant EAR2050246.
文摘Detrital zircon geochronology is reported from the c.1200 m thick Cambro-Ordovician sedimentary succession recovered in core from the COSC-2 continental drilling project in the Scandinavian Caledonides.Above a regolith marking the sub-Cambrian peneplain,a lower to middle Cambrian(?)succession comprises conglomerate,sandstone and shale overlain by gravity flows fining upwards into the Alum Shale Formation.First results of detrital zircon geochronology from the Cambrian(?)succession show that the basal section of the autochthonous cover is characterized by mainly late Paleoproterozoic–early Mesoproterozoic detrital grains.The middle part of the succession is dominated by late Paleoproterozoic detritus with minor Mesoproterozoic and Archean input.The upper part of lower Cambrian(?)succession is characterized by Archean to Cambrian detritus.The maximum depositional age is calculated to 530.5±4 Ma for the upper part of the lower Cambrian succession.Two samples from the Lower Ordovician(?)succession above the Alum Shale Formation show predominantly Mesoproterozoic to early Neoproterozoic(1.5–0.9 Ga)ages.The autochthonous lower Cambrian(?)passive margin succession in the lower section is dominated by local detritus,sourced exclusively from the Eastern Segment of the Sveconorwegian Orogen,which includes the basement studied in COSC-2.Up-section,the provenance shifts towards the Transscandinavian Igneous Belt and Svecofennian Orogen sources,with the youngest part of the succession showing a notable input of Neoproterozoic–Cambrian active margin detritus.The Ordovician(?)succession is characterized by populations,likely derived from the Sveconorwegian Orogen,and a minor cratonic contribution.Statistical analysis of detrital zircon datasets across Baltica suggests that the Southern Baltica/Sandomirian Arc,rather than the Timanian Orogen,was a significant source of detrital material across the paleocontinent.The influence of Timanian Orogen grains is limited to northernmost Scandinavia,whereas Sandomirian detritus reached central Scandinavia in the lower to middle Cambrian and remained prevalent in southern Scandinavia into the Lower Ordovician.
基金Suli Yao is partially supported by a Postdoc Fellowship from Faculty of Science,CUHK.Hongfeng Yang acknowledged the support from National Key R&D Program of China(No.2023YFF0803202)and HKSAR RGC(No.14308523)Zhigao Yang acknowledged the support from the Earthquake Spark Technology Project(No.XH23051B).
文摘Determining the rupture directivity for small earthquakes is challenging due to the small source dimension and limited resolution of far-field observations.In recent years,the burst of near-source observations provides great opportunities to study earthquake rupture.Here we present the rapid determination of the rupture directivity for the 2024 Feidong M4.7 earthquake using only one strong motion station located 4 km from the epicenter.We find that the polarization of S waves evolves during the rupture,indicating an azimuth change during the rupture propagation.Through comparing the data with the synthetic waveforms,we infer that the M4.7 event propagated dominantly to the southwest on the dextral Tanlu fault.Our inference is further validated through comparing the data with records at local stations for M3 earthquakes in the Feidong sequence.Our study highlights the superior application of near-source observations in earthquake source studies.
基金supported by the National Key R&D Program of China(No.2018YFA0606001)the Ozone Formation Mechanism and Control Strategies Project of Research Center of Eco-Environmental Sciences+3 种基金Chinese Academy of Sciences(No.RCEES-CYZX-2020)the Natural Science Foundation of China(No.42171463)H.T.and S.P.were supported by the US National Science Foundation(No.1903722)Andrew Carnegie Fellowship(No.G-F-19–56910).
文摘Surface ozone(O_(3))pollution showed a continuous increasing trend during the recent decades in China,posing an increasing threat to food security.A wide range of yield reductions have been reported and thus more studies are needed to narrow down the uncertainty resulting from spatiotemporal accuracy of O_(3) metrics and extrapolation methods.Based on a high spatial resolution(0.1°)hourly surface O_(3) data,here we analyzed the spatiotemporal O_(3) pollution patterns and impacts on yield,production and economic losses for wheat,rice,and maize in China during 2005–2020.The accumulated O_(3) exposure over a threshold of 40 ppb(AOT40)increased by 10%during 2005–2019,and a decrease of 5.56%was observed in 2020 due to the COVID-19 lockdowns.Rising O_(3) pollution reduced national level wheat,rice and maize yields by 14.51%±0.43%,11.10%±0.6%,and 3.99%±0.11%,respectively.A Business-As-Usual projection suggested that the relative yield loss(RYL)would potentially reach 8%–18%at the national scale by 2050 if no emission control is implemented.COVID-19 lockdowns in 2020 led to significantly reduced RYL for maize(0.52%)and rice(2.17%)but not for wheat(0.11%),with the largest reduction(1.88%–9.4%)in North China Plain,highlighting the potential benefits of emission control.Our findings provided robust evidence that rising O_(3) pollution has significantly affected China’s crop yields,production and economic losses,underscoring the urgent need to curb O_(3) pollution to safeguard food security,particularly in densely populated and industrialized regions.
基金financially supported by the Marine National Park and Sanctuary(MNP&S)Jamnagar,Gujarat State,India through the project,"Mangrove Vegetation Characteristics of Gulf of Kachchh"
文摘The semi-arid mangroves of the Gulf of Kachchh,the largest ecosystems on the west coast of India,are poorly studied in terms of vegetation structure and environmental parameters in spite of their conservation significance.Therefore,it is necessary to document the structural features of these mangroves in view of ongoing coastal industrial development.Mangrove forest structure in 10 locations on the northern and southern coasts of the Gulf of Kachchh were assessed using the line intercept transect method.Descriptions included density of young and mature age classes,tree heights,diameters at breast height(DBH)and aboveground biomass,along with seven significant environmental variables.Mature tree densities ranged from 350 to 1567 ind.ha-1,while average height and girth at breast height ranged from 1.0 to 6.8 m and 3.0 to 137.0 cm,respectively.The majority of trees(55.6%)were in B 1.8 m height class followed by a 1.9 to 2.4 m class(25.1%).DBH was most often in class 2 cm or lower than that.Among the canopy index classes,more trees were recorded in class ≤2 cm.The regeneration density was greater than the recruitment class.This study indicates that the poor structural attributes of Avicennia marina Vierth.var.acutissima Stapf and Mold dominated mangroves are largely due to aridity induced by scarce and erratic rainfall and high soil and water salinities.The results should be valuable in conserving and sustainably managing these mangroves in the face of developmental activities.
基金supported by the CNRT "Nickel and its environment" of New Caledonia
文摘Covered by ultrabasic units for more than a third of its surface,the New Caledonia(South West Pacific)is one of the largest world producers of Ni-ore from lateritic deposits.Almost all outcrops of geological units and open mines contain serpentine and amphibole,also as asbestos varieties.In this geological context,in which weathering processes had a great contribution in the production and dispersion of mineral fibres into the environment,the development of a routinely analytical strategy,able to discriminate an asbestiform fibre from a non-harmful particle,is a pivotal requisite.However,the acquisition of all these parameters is necessary for determining the risk associated to fibres exposition.A multidisciplinary routinely approach,based on the use of complementary simply-to-use but reliable analytical methods is the only possible strategy.In addition,the instrumental apparatus must be easily transportable on the field,directly on the mining site.The employment of specialized tools such as Polarized Light Microscopy associated to Dispersion Staining method(PLM/DS)and portable Raman spectroscopy for identification of environmental asbestos,are proved extremely effective in the improvement of the performance and rapidity of data acquisition and interpretation.Both PLM/DS and handheld Raman devices confirmed to be discriminant in the detection and characterization of asbestos fibres for both serpentine and amphibole.Furthermore,these techniques proved extremely effective even in the presence of strongly fibrous and altered samples.
文摘The Urban Commune of Maradi in Niger experienced increasingly frequent flooding following rainy episodes generating volumes and water flows that are difficult to control in recent years. This study aims to determine the impacts of runoff water in Commune II of Maradi City and to assess the role of urban planning in runoff management, as well as the strengths and weaknesses of urban sanitation in Maradi. The methodological approach used consisted of: 1) an interpretation of documentary data, 2) gathering information on runoff at several sites in the study area, and 3) interviews and questionnaires with local communities. This approach made it possible to understand the degree of vulnerability of the populations to flooding and then to propose sustainable solutions to reduce the vulnerability of the affected populations, through the implementation of effective urban rainwater management practices (USWMP). The results show that the impacts of runoff are mainly related to the lack of adequate storm water drainage networks in the area, but also to the nature of the habitats. Geomorphological factors such as the nature of the soil, the slope of the terrain and the altitude increase the degree of risk. In addition, the inadequacy and dilapidation of the drainage systems of the canals and above all the anarchic occupation of the land linked to accelerated urbanization are the cause of flooding by stagnation of rainwater. A phenomenon now linked to numerous deteriorations of urban equipment, the runoff of rainwater in the city of Maradi carries so many pollutants that municipalities, businesses and individuals should put in place pollution prevention measures.
文摘Introduction:Pharmaceuticals are regarded as emerging contaminants in the environment.In recent years,their destiny and removal have piqued people’s interest.Methods:Examine how well conventional wastewater treatment facilities and cutting-edge technologies(ultrafiltration and reverse osmosis)can remove specific pharmaceutical compounds from water,with a focus on the compounds'environmental status,their origin,deterioration,metabolites,and the capacities of these facilities.Results and discussion:the ability and efficacy of sophisticated treatment technologies such as membrane separation,adsorption,and AOPs(Advanced Oxidation Processes)in eliminating chosen commonly used drugs from water are explored.Batch adsorption experiments were integrated with appropriate adsorption isotherms and appropriate kinetic models to predict the final extent of pollutant removal by this method.Continuous filtration mode was also investigated.Combining filtration(using AC(Activated Carbon)and micelle-clay granule complexes)with AOPs improves the economy of treating wastewater,which contains recalcitrant PhACs(Pharmaceutical Compounds).
基金supported by China Geological Survey(Nos.12120113094000,1212010811033 and 12120113093600)National Natural Science Foundation of China(Nos.41172062 and 41572052)
文摘U–Pb analysis of zircons from igneous rocks in the Elashan Mountain,easternmost segment of the East Kunlun Orogen yielded 252–232 Ma.Geochemically,these rocks are mainly high in SiO_(2),K_2O and K_2O+Na_2O contents,low in P_2O_5 and TiO_(2) contents,depleted in Ba,Sr,P,Ti and enriched in U,Hf,Zr,showing features of I–type granite.The zirconεHf(t)values of the Early Triassic Jiamuge'er rhyolite porphyry(252±3 Ma)are positive(+1.6 to+12.1),suggesting a juvenile crustal source mixing with little old crustal component,and the zirconεHf(t)values of the Middle Triassic Manzhang'gang granodiorite(244±3 Ma)and Dehailong diorite(237±3 Ma)are predominately negative(-8.4 to+1.0),indicating an older crustal source.In comparison,the zirconεHf(t)values of the Late Triassic syenogranites from Suigen'ergang(234±2Ma),Ge'ermugang(233±2 Ma)and Yue'ergen(232±3 Ma)plutons vary from-3.8 to+5.0,suggesting a crust-mantle mixing source.From Early–Middle Triassic(252–237 Ma)to Late Triassic(234–232 Ma),the geochemical characteristics of these rocks show the change from a subduction–collision setting to a post-collision or within-plate setting.By comparing of these new age data with 77 zircon U–Pb ages of igneous rocks of the eastern part of East Kunlun orogen from published literatures,we conclude that the igneous rocks of Elashan Mountain and these of the eastern part of East Kunlun Orogen belong to one magmatic belt.All these data indicate that the Triassic magmatic events of the eastern part of East Kunlun Orogen can be divided into three stages:252–238 Ma,238–226 Ma and 226–212 Ma.Statistically,the averageεHf(t)values of the threestage igneous rocks show a tendency,from the old to young,from-0.75±0.25 to lower-2.65±0.52 and then to-1.22±0.25,respectively,which reveal the change of their sources.These characteristics can be explained as a crust-mantle mixing source generated in a subductional stage,mainly crust source in a syn–collisional stage and a crust-mantle mixing source(lower crust with mantle-derived underplating magma)in a post-collisional stage.The identification of these three magmatic events in the Elashan Mountain,including all the eastern part of East Kunlun Orogen,provides new evidence for better understanding of the tectonic evolution of the northward subduction and closure of the Paleo-Tethyan(252–238 Ma),the collision of the Songpan–Ganzi block with the southern margin of Qaidam block(238–226 Ma),and the post–collisional setting(226–212 Ma)during the Early Mesozoic period.
基金supported by the National Natural Science Foundation of China(Nos.41502264,51134005)the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20130023120016)the Fundamental Research Funds for the Central Universities of China(No.2010QL07)
文摘Pore structure characteristics of rock are a great concern for researchers and practitioners in rock mechanics and rock engineering fields. In this study, mercury intrusion porosimetry（MIP） was used to measure pore size distribution, as well as several important index parameters of pore structure, for seven common types of deep sedimentary rocks with a total of fifty rock samples. Results show a similar pore size distribution pattern of the rock samples in the same lithological group, but remarkable differences among different lithological groups. Among seven investigated rock types, mudstone has the smallest porosity of 3.37%, while conglomerate has the largest value of 18.8%. It is also found that the porosity of rock types with finer grain size is lower than those with coarser grain size. Meanwhile, a comparison of frequency distribution at ten intervals of pore-throat diameter among seven types of sedimentary rocks reveals that different rock types have different dominant pore-size ranges. Furthermore, permeability of the investigated sedimentary rock samples was derived based on MIP data using reported theoretical equations. Among seven rock types, mudstone has the lowest averaged permeability（3.64×10^（-6） mD） while conglomerate has the highest one（8.59×10^（-4） mD）. From mudstone to conglomerate, rock permeability increases with an increase of grain size, with only an exception of siltstone which has a relatively larger porosity value. Finally, regression analysis show that there is a good fitting（R^2=0.95） between permeability and porosity which could be easily used to derive reliable permeability values of similar kinds of engineering rocks.
