Geomagnetic storm events have a strong influence on the ionosphere–thermosphere(I-T)coupling system.Analyzing the regional response process of the I-T system and its differences across the northern and southern hemis...Geomagnetic storm events have a strong influence on the ionosphere–thermosphere(I-T)coupling system.Analyzing the regional response process of the I-T system and its differences across the northern and southern hemispheres is an important but challenging task.In this study,we used a combination of multiple observations and a model simulation to examine the north–south hemispheric difference in the I-T coupling system in the American and Asian sectors during the geomagnetic superstorm that occurred in May 2024.Observations of the total electron content(TEC)showed that the Asian sector had negative storms in the northern hemisphere and positive storms in the southern hemisphere,a process that exacerbated the hemispheric differences in the TEC.However,both hemispheres of the American sector showed negative storms.The thermospheric composition changes also differed between the two sectors,and their variation could partially explain the hemispheric differences caused by positive and negative storms.Moreover,the influence of the thermospheric density change was less than that of the thermospheric composition.Finally,the dynamic effect of the thermospheric wind and the plasma transport processes strongly modulated the north–south differences in the TEC at nighttime in the American and Asian sectors,respectively,during this superstorm.展开更多
The extant literature has produced mixed evidence on the relationship between finan-cial development and ecological sustainability.This work addresses this conundrum by investigating financial development’s direct an...The extant literature has produced mixed evidence on the relationship between finan-cial development and ecological sustainability.This work addresses this conundrum by investigating financial development’s direct and indirect consequences on ecologi-cal quality utilizing the environmental Kuznets curve(EKC)methodological approach.Our empirical analysis is based on the novel dynamic autoregressive distributed lag simulations approach for South Africa between 1960 and 2020.The results,which used five distinct financial development measures,demonstrate that financial develop-ment boosts ecological integrity and environmental sustainability over the long and short terms.In the instance of South Africa,we additionally confirm the validity of the EKC theory.More importantly,the outcomes of the indirect channels demonstrate that financial development increases energy usage’s role in causing pollution while attenuating the detrimental impacts of economic growth,trade openness,and foreign direct investment on ecological quality.Moreover,the presence of an inadequate financial system is a requirement for the basis of the pollution haven hypothesis(PHH),which we examine using trade openness and foreign direct investment variables.PHH for both of these variables disappears when financial development crosses specified thresholds.Finally,industrial value addition destroys ecological quality while tech-nological innovation enhances it.This research provides some crucial policy recom-mendations and fresh perspectives for South Africa as it develops national initiatives to support ecological sustainability and reach its net zero emissions goal.展开更多
The argument over fiscal decentralization and carbon dioxide emission(CO_(2))reduction has received much attention.However,evidence to back this claim is limited.Economic theory predicts that fiscal decentralization a...The argument over fiscal decentralization and carbon dioxide emission(CO_(2))reduction has received much attention.However,evidence to back this claim is limited.Economic theory predicts that fiscal decentralization affects environmental quality,but the specifics of this relationship are still up for debate.Some scholars noted that fiscal decentralization might lead to a race to the top,whereas others contended that it would result in a race to the bottom.In light of the current debates in environmental and development economics,this study aims to provide insight into how this relationship may function in South Africa from 1960 to 2020.In contrast to the existing research,the present study uses a novel dynamic autoregressive distributed lag simulation approach to assess the positive and negative changes in fiscal decentralization,scale effect,technique effect,technological innovation,foreign direct investment,energy consumption,industrial growth,and trade openness on CO_(2)emissions.The following are the main findings:(i)Fiscal decentralization had a CO_(2)emission reduction impact in the short and long run,highlighting the presence of the race to the top approach.(ii)Economic growth(as represented by the scale effect)eroded ecological integrity.However,its square(as expressed by technique effect)aided in strengthening ecological protection,validating the environmental Kuznets curve hypothesis.(iii)CO_(2)emissions were driven by energy utilization,trade openness,industrial value-added,and foreign direct investment,whereas technological innovation boosted ecological integrity.Findings suggest that further fiscal decentralization should be undertaken through further devolution of power to local entities,particularly regarding environmental policy issues,to maintain South Africa’s ecological sustainability.South Africa should also establish policies to improve environmental sustainability by strengthening a lower layer of government and clarifying responsibilities at the national and local levels to fulfill the energy-saving functions of fiscal expenditures.展开更多
The mode-2 internal solitary waves(ISWs)generated by mode-2 internal tide(IT)are identified by mooring observations in the northern South China Sea(SCS)from 2016 to 2017.Two mode-2 ISWs with a re-appearance period of ...The mode-2 internal solitary waves(ISWs)generated by mode-2 internal tide(IT)are identified by mooring observations in the northern South China Sea(SCS)from 2016 to 2017.Two mode-2 ISWs with a re-appearance period of 24.9 h observed on 29 and 30 July 2016 are characterized by type-b ISWs.They occurred when the isotherms compressed obviously in the vertical direction.Modal decomposition of IT horizontal currents shows that the vertical compression of the isotherms is mainly caused by diurnal mode-2 IT.The analysis of the role of the density stratification reveals that a deeper and thinner pycnocline is favorable for generation of mode-2 ISWs rather than pycnocline intensity.By comparing the mode-2 nonlinear,dispersion coefficients and the Ursell numbers calculated based on the stratification associated with different kinds of ITs with the observation results,it is shown that the diurnal mode-2 IT plays a crucial role in the generation of the mode-2 ISWs.When the diurnal mode-2 IT interacts with the semidiurnal IT and causes a deeper and thinner pycnocline,the mode-2 ISWs are easily excited.展开更多
Nitrogen fixation is one of the most important sources of new nitrogen in the ocean and thus profoundly affects the nitrogen and carbon biogeochemical processes.The distribution,controlling factors,and flux of N2 fixa...Nitrogen fixation is one of the most important sources of new nitrogen in the ocean and thus profoundly affects the nitrogen and carbon biogeochemical processes.The distribution,controlling factors,and flux of N2 fixation in the global ocean remain uncertain,partly because of the lack of methodological uniformity.The^(15)N_(2)tracer assay(the original bubble method→the^(15)N_(2)-enriched seawater method→the modified bubble method)is the mainstream method for field measurements of N2 fixation rates(NFRs),among which the original bubble method is the most frequently used.However,accumulating evidence has suggested an underestimation of NFRs when using this method.To improve the availability of previous data,we compared NFRs measured by three^(15)N_(2)tracer assays in the South China Sea.Our results indicate that the relationship between NFRs measured by the original bubble method and the^(15)N_(2)-enriched seawater method varies obviously with area and season,which may be influenced by incubation time,diazotrophic composition,and environmental factors.In comparison,the relationship between NFRs measured by the original bubble method and the modified bubble method is more stable,indicating that the N2 fixation rates based on the original bubble methods may be underestimated by approximately 50%.Based on this result,we revised the flux of N2 fixation in the South China Sea to 40 mmol/(m2·a).Our results improve the availability and comparability of literature NFR data in the South China Sea.The comparison of the^(15)N_(2)tracer assay for NFRs measurements on a larger scale is urgently necessary over the global ocean for a more robust understanding of the role of N2 fixation in the marine nitrogen cycle.展开更多
Hexangulaconulariids,an extinct family of medusozoan small shelly fossils(SSFs),were a conspicuous component of early Cambrian,shallow marine platform communities in South China.Described herein is Septuconularia cras...Hexangulaconulariids,an extinct family of medusozoan small shelly fossils(SSFs),were a conspicuous component of early Cambrian,shallow marine platform communities in South China.Described herein is Septuconularia crassiformis sp.nov.from Bed 5 of the Yanjiahe Formation(Cambrian Stage 2)in the Three Gorges area of Hubei Province.The new species differs from the type and only other known species,S.yanjiaheensis,in the shape of the abapical portion and in the degree of curvature of the adapertural margin.The anatomy of the apical portion of the new species is unknown.The diagnosis of the genus Septuconularia is emended and the spatio-temporal distribution of hexangulaconulariids in South China is summarized.Finally,S.yanjiaheensis,with its slit-like aperture and very narrow transverse cross-section,may have been better adapted to the shallow platform environment than the broader S.crassiformis,which appears to have been less common than the type species.展开更多
A multilayer study of pCO2 for the Yellow and South China Seas in the surface waters was conducted based on data from four cruises sponsored by the China SOLAS Project in 2005 and 2006,including data for the surface m...A multilayer study of pCO2 for the Yellow and South China Seas in the surface waters was conducted based on data from four cruises sponsored by the China SOLAS Project in 2005 and 2006,including data for the surface microlayer(SML) ,subsurface layer(SSL) and surface layer(SL) . The carbon fluxes across the air-sea interface were calculated. The results showed that the pCO2 values in the surface waters of the study area decreased in the following order:pCO2 SML> pCO2 SSL> pCO2 SL. The highest values were found in March for all SML,SSL and SL,followed by those in April,and the lowest were in May. The pCO2 values had a significant positive correlation with temperature or salinity. While there was no relationship between pCO2 and longitude,there was a significant negative correlation between it and latitude,i.e.,'high latitude low pCO2'. By using four calculation models,the carbon dioxide fluxes(FC O2) in spring in the Yellow and South China Seas,which were found to act as a 'sink' of atmospheric CO2,were preliminarily estimated on the basis of the pCO2 data in the SML to be -7.00×106 t C and -22.35×106 t C,respectively. It is suggested that the FC O2calculated on the basis of pCO2 data in the SML is more reliable than that calculated on the basis of those in the SL.展开更多
The effects of fertilizers and water content on N2O emission were studied using the three most typical plantation soils. Soil incubations were performed and fertilization and water content treatments were designed. At...The effects of fertilizers and water content on N2O emission were studied using the three most typical plantation soils. Soil incubations were performed and fertilization and water content treatments were designed. At 25% of saturated water content（SWC）, N2O emissions from the soil treated with urea, KNO3, （NH4）2 SO, and KH2 PO, were compared at application rates of 0, 100, 200, 300 and 500 kg/hm2. At 80% of SWC, similar experiments were carried out but at only one application rate（500 kg/hm^2）. N2O emissions at various water contents（20%, 35%, 50%, 65%, 80% and 100% of SWC） were studied. At low water content（25% of SWC）, neither nitrogen nor phosphorus（or potassium） fertilizers led to a high level of N2O emission, which generally ranged from 2.03 to 29.02 μg/（m^2·h）. However, at high water content（80% SWC）, the fertilizers resulted in much greater N2O emission irregardless of soil tested. The highest N2O emission rates after 24 h of water addition were 1233 lag/（ m^2 ·h） for S. superba soil, 1507 lag/（m^2 · h） for P. elliottii soil and 1869 lag/ （m^2 h） for A. mangium soil respectively. N2O emission from soils treated with urea, （NH4）2SO, and KH2PO, immediately dropped to a low level but steadily increased to a very high level for the soil treated with KNO3. High NO3^- content was a basis of high level of N2O emission. N2O emission rates from soils peaked shortly after flooding, rapidly dropping to a very low level in soil from non-legume plantations, but lasting for a relatively long period in soil from legume plantations. When soil water content increased equaling to or higher than 65%, the accumulated N2O emission over a period of 13 d ranged from 20.21-29.78 mg/m^2 for S. superba, 30.57-70.12 mg/m^2 for P. elliottii and 300.89-430.51 mg/m^2 for A. mangium. The critical water content was 50% of SWC, above which a high level of N2O emission could be expected, and below which very little N2O emissions were detected. The results suggest that, at low water content（ 〈 50% of SWC）, the fertilization practice is safe with regard to N2O emissions, but at high water content（ 〉 50% of SWC）, nitrogen fertilizer in the form of nitrate could yield a 100-fold increase in N2O emissions. Legume plantations like A. mangium should be avoided in low lands which could easily suffer from flooding or poor drainage.展开更多
The South Yellow Sea Basin(SYSB) has multiple sets of proven source rocks and good hydrocarbon prospects,but no industrial oil and gas has been explored at present.To solve this puzzle for petroleum geologists,we syst...The South Yellow Sea Basin(SYSB) has multiple sets of proven source rocks and good hydrocarbon prospects,but no industrial oil and gas has been explored at present.To solve this puzzle for petroleum geologists,we systematically investigated the marine hydrocarbon geological conditions based on cores and testing data from borehole CSDP-2,the first exploration well with continuous coring in SYSB.The qualities of source rocks are evaluated in detail according to organic matter abundance,type,and maturity.The reservoir characterization mainly includes porosity,permeability,and reservoir space.Displacement pressure test and stratum thickness are the main foundations for defining the caprocks.Then,the oil-source rock correlation in the Permian and stratum model are analyzed to determine the favorable source-reservoir-caprock assemblages.The results show that three sets of effective source rocks(the Lower Triassic,Upper Permian,and Lower Permian),two sets of tight sandstone re servoirs(the Upper Permian and Lower Silurian-Upper Devonian),and two sets of caprocks(the Lower Triassic and Carboniferous) combine to constitute the hydrocarbon reservoir-forming as se mblages of "lower-ge neration and upper-accumlation" and "self-generation and self-accumlation",thus laying a solid foundation for promising petroleum prospects.The three sets of marine source rocks are characterized by successive generation and expulsion stages,which guarantees multistage hydrocarbon accumulation.Another three sets of continental source rocks distributed across the Middle Jurassic,Upper Cretaceous,and Paleogene depression areas,especially in the Northern Depression,may supplement some hydrocarbons for the Central Uplift through faults and the Indosinian unconformity.The favorable Permian exploration strata have been identified in the Central Uplift of SYSB.First,the Lower Permian and Upper Permian source rocks with high organic matter abundance and high thermal maturity supply sufficient hydrocarbons.Secondly,the interbedding relationship between the source rocks and sandstones in the Upper Permian strata ensures that hydrocarbons have been migrated into the nearby Upper Permian sandstones,reflecting near-source hydrocarbon accumulation.Finally,the good sealing property of the Lower Triassic Qinglong Formation caprocks plays an indispensable role in hydrocarbon preservation of the Permian reservoirs.This conclusion is supported by direct oil shows,gas logging anomalous layers,and hydrocarbon-bearing fluid inclusions.展开更多
Marginal seas play important roles in regulating the global carbon budget, but there are great uncertainties in estimating carbon sources and sinks in the continental margins. A Pacific basin-wide physical-biogeochemi...Marginal seas play important roles in regulating the global carbon budget, but there are great uncertainties in estimating carbon sources and sinks in the continental margins. A Pacific basin-wide physical-biogeochemical model is used to estimate primary productivity and air-sea CO_2 flux in the South China Sea（SCS）, the East China Sea（ECS）, and the Yellow Sea（YS）. The model is forced with daily air-sea fluxes which are derived from the NCEP2 reanalysis from 1982 to 2005. During the period of time, the modeled monthly-mean air-sea CO_2 fluxes in these three marginal seas altered from an atmospheric carbon sink in winter to a source in summer. On annualmean basis, the SCS acts as a source of carbon to the atmosphere（16 Tg/a, calculated by carbon, released to the atmosphere）, and the ECS and the YS are sinks for atmospheric carbon（–6.73 Tg/a and –5.23 Tg/a, respectively,absorbed by the ocean）. The model results suggest that the sea surface temperature（SST） controls the spatial and temporal variations of the oceanic pCO_2 in the SCS and ECS, and biological removal of carbon plays a compensating role in modulating the variability of the oceanic pCO_2 and determining its strength in each sea,especially in the ECS and the SCS. However, the biological activity is the dominating factor for controlling the oceanic pCO_2 in the YS. The modeled depth-integrated primary production（IPP） over the euphotic zone shows seasonal variation features with annual-mean values of 293, 297, and 315 mg/（m^2·d） in the SCS, the ECS, and the YS, respectively. The model-integrated annual-mean new production（uptake of nitrate） values, as in carbon units, are 103, 109, and 139 mg/（m^2·d）, which yield the f-ratios of 0.35, 0.37, and 0.45 for the SCS, the ECS, and the YS, respectively. Compared to the productivity in the ECS and the YS, the seasonal variation of biological productivity in the SCS is rather weak. The atmospheric pCO_2 increases from 1982 to 2005, which is consistent with the anthropogenic CO_2 input to the atmosphere. The oceanic pCO_2 increases in responses to the atmospheric pCO_2 that drives air-sea CO_2 flux in the model. The modeled increase rate of oceanic pCO_2 is0.91 μatm/a in the YS, 1.04 μatm/a in the ECS, and 1.66 μatm/a in the SCS, respectively.展开更多
In order to understand the water mass exchange between the South China Sea and the West PhilippineSea, and to study the dissolved carbonate system in the seas surrounding Taiwan Island, we participated in five WOCEcru...In order to understand the water mass exchange between the South China Sea and the West PhilippineSea, and to study the dissolved carbonate system in the seas surrounding Taiwan Island, we participated in five WOCEcruises (Cruises 257, 262, 266, 287 and 316) aboard R/V Ocean Researcher 1. The areas studied were the South ChinaSea, the West Philippine Sea and the Bashi Channel. Temperature, salinity, pH, alkalinity and total CO2 were measured.Our data indicate that because of the interference of the submarine topography and the Kuroshio axis, there existsa 'front' south of the Lanyu Islet. East of it, the water mass belongs to the West Philippine Sea, on the west in themixed water of the South China Sea and the West Philippine Sea.The South China Sea deep water should have the characteristics similar to the water at about 2 200 m in the WestPhilippine Sea. The calculated results from the residence time, the inorganic carbon dissolution rate and the organic carbon decomposition rate show that the differences between these two water masses should be between 0. 008～0. 023 inpH, 5. 2～15. 0 μmol/kg in apparent oxygen utilization, 3. 6～10. 2 μmol/kg in alkalinity and 6. 4～18. 4 μmol/kg intotal CO2, respectively. The measured results show that there are no distinguishable differences between these two watermasses, implying a short deep water residence time of approximately 40 a.The anthropogenic CO2 penetrates to roughly 500 m, slightly shallower than found in the West Philippine Sea. Theentire South China Sea contains (0. 38±0. 1 ) × 1015 g excess CO2.展开更多
The large-scale upper oceanic circulation in the South China Sea (SCS) during the northeast monsoon was investigited using a 2 1/2-layer model inrolving entrainment and detraininent at the interface between the upper ...The large-scale upper oceanic circulation in the South China Sea (SCS) during the northeast monsoon was investigited using a 2 1/2-layer model inrolving entrainment and detraininent at the interface between the upper mixed layer and the seasonal thermocline. The model allows heat fluxes at the surface and at the interfaee with a reaxation scheme, the temperatures of the two active layers can vary. The model basin is idenical to the SCS lateral boundary with bottom topography of 50 m or more and is regarded as an enclosed basin by neglecting inflow and outflow through the straits, and is forced by the climetological wind stna of 12 calendar months. It was found tha the upper oceanic currents in winter were mainly wind-driven. Most aspects of streams reported by observations were simulated with eddyresolving.展开更多
The South Yellow Sea basin is filled with Mesozoic-Cenozoic continental sediments overlying pre-Palaeozoic and Mesozoic-Palaeozoic marine sediments.Conventional multi-channel seismic data cannot describe the velocity ...The South Yellow Sea basin is filled with Mesozoic-Cenozoic continental sediments overlying pre-Palaeozoic and Mesozoic-Palaeozoic marine sediments.Conventional multi-channel seismic data cannot describe the velocity structure of the marine residual basin in detail,leading to the lack of a deeper understanding of the distribution and lithology owing to strong energy shielding on the top interface of marine sediments.In this study,we present seismic tomography data from ocean bottom seismographs that describe the NEE-trending velocity distributions of the basin.The results indicate that strong velocity variations occur at shallow crustal levels.Horizontal velocity bodies show good correlation with surface geological features,and multi-layer features exist in the vertical velocity framework(depth:0–10 km).The analyses of the velocity model,gravity data,magnetic data,multichannel seismic profiles,and drilling data showed that high-velocity anomalies(>6.5 km/s)of small(thickness:1–2 km)and large(thickness:>5 km)scales were caused by igneous complexes in the multi-layer structure,which were active during the Palaeogene.Possible locations of good Mesozoic and Palaeozoic marine strata are limited to the Central Uplift and the western part of the Northern Depression along the wide-angle ocean bottom seismograph array.Following the Indosinian movement,a strong compression existed in the Northern Depression during the extensional phase that caused the formation of folds in the middle of the survey line.This study is useful for reconstructing the regional tectonic evolution and delineating the distribution of the marine residual basin in the South Yellow Sea basin.展开更多
The monthly prediction skill for tropical cyclone(TC)activity in the South China Sea(SCS)during the typhoon season(July to November)was evaluated using the FGOALS-f2 ensemble prediction system.Specifically,the predict...The monthly prediction skill for tropical cyclone(TC)activity in the South China Sea(SCS)during the typhoon season(July to November)was evaluated using the FGOALS-f2 ensemble prediction system.Specifically,the prediction skill of the system at a 10-day lead time for monthly TC activity is given based on 35-year(1981–2015)hindcasts with 24 ensemble members.The results show that FGOALS-f2 can capture the climatology of TC track densities in each month,but there is a delay in the monthly southward movement in the area of high track densities of TCs.The temporal correlation coefficient of TC frequency fluctuates across the different months,among which the highest appears in October(0.59)and the lowest in August(0.30).The rank correlation coefficients of TC track densities are relatively higher(R>0.6)in July,September,and November,while those in August and October are relatively lower(R within 0.2 to 0.6).For real-time prediction of TCs in 2020(July to November),FGOALS-f2 demonstrates a skillful probabilistic prediction of TC genesis and movement.Besides,the system successfully forecasts the correct sign of monthly anomalies of TC frequency and accumulated cyclone energy for 2020(July to November)in the SCS.展开更多
This study depicts the sub-seasonal prediction of the South China Sea summer monsoon onset(SCSSMO)and investigates the associated oceanic and atmospheric processes,utilizing the hindcasts of the National Centers for E...This study depicts the sub-seasonal prediction of the South China Sea summer monsoon onset(SCSSMO)and investigates the associated oceanic and atmospheric processes,utilizing the hindcasts of the National Centers for Environmental Prediction(NCEP)Climate Forecast System version 2(CFSv2).Typically,the SCSSMO is accompanied by an eastward retreat of the western North Pacific subtropical high(WNPSH),development of the cross-equatorial flow,and an increase in the east-west sea surface temperature(SST)gradient.These features are favorable for the onset of westerlies and strengthening of convection and precipitation over the South China Sea(SCS).A more vigorous SCSSMO process shows a higher predictability,and vice versa.The NCEP CFSv2 can successfully predict the onset date and evolution of the monsoon about 4 pentads(20 days)in advance(within 1–2 pentads)for more forceful(less vigorous)SCSSMO processes.On the other hand,the climatological SCSSMO that occurs around the 27th pentad can be accurately predicted in one pentad,and the predicted SCSSMO occurs 1–2 pentads earlier than the observed with a weaker intensity at longer leadtimes.Warm SST biases appear over the western equatorial Pacific preceding the SCSSMO.These biases induce a weaker-thanobserved WNPSH as a Gill-type response,leading to weakened low-level easterlies over the SCS and hence an earlier and less vigorous SCSSMO.In addition,after the SCSSMO,remarkable warm biases over the eastern Indian Ocean and the SCS and cold biases over the WNP induce weaker-than-observed westerlies over the SCS,thus also contributing to the less vigorous SCSSMO.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 42030202, 42241115, and 42174204)the China Postdoctoral Science Foundation (Grant No. 2023M743467)+2 种基金the Youth Innovation Promotion Association of the Chinese Academy of Sciences (Grant No. Y202021)the National Key R&D Program of China (Grant No. 2022YFF0504400)the Opening Funding of the Chinese Academy of Sciences dedicated to the Chinese Meridian Project
文摘Geomagnetic storm events have a strong influence on the ionosphere–thermosphere(I-T)coupling system.Analyzing the regional response process of the I-T system and its differences across the northern and southern hemispheres is an important but challenging task.In this study,we used a combination of multiple observations and a model simulation to examine the north–south hemispheric difference in the I-T coupling system in the American and Asian sectors during the geomagnetic superstorm that occurred in May 2024.Observations of the total electron content(TEC)showed that the Asian sector had negative storms in the northern hemisphere and positive storms in the southern hemisphere,a process that exacerbated the hemispheric differences in the TEC.However,both hemispheres of the American sector showed negative storms.The thermospheric composition changes also differed between the two sectors,and their variation could partially explain the hemispheric differences caused by positive and negative storms.Moreover,the influence of the thermospheric density change was less than that of the thermospheric composition.Finally,the dynamic effect of the thermospheric wind and the plasma transport processes strongly modulated the north–south differences in the TEC at nighttime in the American and Asian sectors,respectively,during this superstorm.
文摘The extant literature has produced mixed evidence on the relationship between finan-cial development and ecological sustainability.This work addresses this conundrum by investigating financial development’s direct and indirect consequences on ecologi-cal quality utilizing the environmental Kuznets curve(EKC)methodological approach.Our empirical analysis is based on the novel dynamic autoregressive distributed lag simulations approach for South Africa between 1960 and 2020.The results,which used five distinct financial development measures,demonstrate that financial develop-ment boosts ecological integrity and environmental sustainability over the long and short terms.In the instance of South Africa,we additionally confirm the validity of the EKC theory.More importantly,the outcomes of the indirect channels demonstrate that financial development increases energy usage’s role in causing pollution while attenuating the detrimental impacts of economic growth,trade openness,and foreign direct investment on ecological quality.Moreover,the presence of an inadequate financial system is a requirement for the basis of the pollution haven hypothesis(PHH),which we examine using trade openness and foreign direct investment variables.PHH for both of these variables disappears when financial development crosses specified thresholds.Finally,industrial value addition destroys ecological quality while tech-nological innovation enhances it.This research provides some crucial policy recom-mendations and fresh perspectives for South Africa as it develops national initiatives to support ecological sustainability and reach its net zero emissions goal.
文摘The argument over fiscal decentralization and carbon dioxide emission(CO_(2))reduction has received much attention.However,evidence to back this claim is limited.Economic theory predicts that fiscal decentralization affects environmental quality,but the specifics of this relationship are still up for debate.Some scholars noted that fiscal decentralization might lead to a race to the top,whereas others contended that it would result in a race to the bottom.In light of the current debates in environmental and development economics,this study aims to provide insight into how this relationship may function in South Africa from 1960 to 2020.In contrast to the existing research,the present study uses a novel dynamic autoregressive distributed lag simulation approach to assess the positive and negative changes in fiscal decentralization,scale effect,technique effect,technological innovation,foreign direct investment,energy consumption,industrial growth,and trade openness on CO_(2)emissions.The following are the main findings:(i)Fiscal decentralization had a CO_(2)emission reduction impact in the short and long run,highlighting the presence of the race to the top approach.(ii)Economic growth(as represented by the scale effect)eroded ecological integrity.However,its square(as expressed by technique effect)aided in strengthening ecological protection,validating the environmental Kuznets curve hypothesis.(iii)CO_(2)emissions were driven by energy utilization,trade openness,industrial value-added,and foreign direct investment,whereas technological innovation boosted ecological integrity.Findings suggest that further fiscal decentralization should be undertaken through further devolution of power to local entities,particularly regarding environmental policy issues,to maintain South Africa’s ecological sustainability.South Africa should also establish policies to improve environmental sustainability by strengthening a lower layer of government and clarifying responsibilities at the national and local levels to fulfill the energy-saving functions of fiscal expenditures.
基金The National Science and Technology Major Project under contract No.2016ZX05057015the National Natural Science Foundation of China(NSFC)under contract Nos 41376038+6 种基金4040600941806123 and 41506038the NSFC-Shandong Joint Fund for Marine Science Research Centers under contract No.U1606405the National Program on Global Change and Air-Sea Interaction under contract Nos GASI-03-01-01-02GASI-02-IND-STSsum and GASI-IPOVAI-01-05the Public Science and Technology Research Funds Projects of Ocean under contract No.200905024the National Key Scientific Instrument and Equipment Development Projects under contract No.2012YQ12003908。
文摘The mode-2 internal solitary waves(ISWs)generated by mode-2 internal tide(IT)are identified by mooring observations in the northern South China Sea(SCS)from 2016 to 2017.Two mode-2 ISWs with a re-appearance period of 24.9 h observed on 29 and 30 July 2016 are characterized by type-b ISWs.They occurred when the isotherms compressed obviously in the vertical direction.Modal decomposition of IT horizontal currents shows that the vertical compression of the isotherms is mainly caused by diurnal mode-2 IT.The analysis of the role of the density stratification reveals that a deeper and thinner pycnocline is favorable for generation of mode-2 ISWs rather than pycnocline intensity.By comparing the mode-2 nonlinear,dispersion coefficients and the Ursell numbers calculated based on the stratification associated with different kinds of ITs with the observation results,it is shown that the diurnal mode-2 IT plays a crucial role in the generation of the mode-2 ISWs.When the diurnal mode-2 IT interacts with the semidiurnal IT and causes a deeper and thinner pycnocline,the mode-2 ISWs are easily excited.
基金The National Natural Science Foundation of China under contract Nos 42076042 and 41721005the Fund of Ministry of Science and Technology of China under contract No.2017FY201403the Fund of China Ocean Mineral Resources R&D Association under contract No.DY135-13-E2-03.
文摘Nitrogen fixation is one of the most important sources of new nitrogen in the ocean and thus profoundly affects the nitrogen and carbon biogeochemical processes.The distribution,controlling factors,and flux of N2 fixation in the global ocean remain uncertain,partly because of the lack of methodological uniformity.The^(15)N_(2)tracer assay(the original bubble method→the^(15)N_(2)-enriched seawater method→the modified bubble method)is the mainstream method for field measurements of N2 fixation rates(NFRs),among which the original bubble method is the most frequently used.However,accumulating evidence has suggested an underestimation of NFRs when using this method.To improve the availability of previous data,we compared NFRs measured by three^(15)N_(2)tracer assays in the South China Sea.Our results indicate that the relationship between NFRs measured by the original bubble method and the^(15)N_(2)-enriched seawater method varies obviously with area and season,which may be influenced by incubation time,diazotrophic composition,and environmental factors.In comparison,the relationship between NFRs measured by the original bubble method and the modified bubble method is more stable,indicating that the N2 fixation rates based on the original bubble methods may be underestimated by approximately 50%.Based on this result,we revised the flux of N2 fixation in the South China Sea to 40 mmol/(m2·a).Our results improve the availability and comparability of literature NFR data in the South China Sea.The comparison of the^(15)N_(2)tracer assay for NFRs measurements on a larger scale is urgently necessary over the global ocean for a more robust understanding of the role of N2 fixation in the marine nitrogen cycle.
基金This study was financially supported by the Natural Science Foundation of China(Grant Nos.42172016,41890844,41890840,41621003,41772010,41720104002)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB26000000)the Key Scientific and Technological Innovation Team Project in Shaanxi Province and the State Key Laboratory of Palaeobiology and Stratigraphy(Nanjing Institute of Geology and Palaeontology,CAS,Grant Nos.203106,163107).
文摘Hexangulaconulariids,an extinct family of medusozoan small shelly fossils(SSFs),were a conspicuous component of early Cambrian,shallow marine platform communities in South China.Described herein is Septuconularia crassiformis sp.nov.from Bed 5 of the Yanjiahe Formation(Cambrian Stage 2)in the Three Gorges area of Hubei Province.The new species differs from the type and only other known species,S.yanjiaheensis,in the shape of the abapical portion and in the degree of curvature of the adapertural margin.The anatomy of the apical portion of the new species is unknown.The diagnosis of the genus Septuconularia is emended and the spatio-temporal distribution of hexangulaconulariids in South China is summarized.Finally,S.yanjiaheensis,with its slit-like aperture and very narrow transverse cross-section,may have been better adapted to the shallow platform environment than the broader S.crassiformis,which appears to have been less common than the type species.
基金This work was supported by the Key Project of the National Natural Science Foundation of China(No.40490263)the National Natural Science Foundation of China(Nos.40706040,40376022 and 40606023)+1 种基金the Doctoral Program for Higher Education(20030423007)Scientific Research Promotional fund for Middle-age and Young Scientist of Shandong Province(2007BS08015).
文摘A multilayer study of pCO2 for the Yellow and South China Seas in the surface waters was conducted based on data from four cruises sponsored by the China SOLAS Project in 2005 and 2006,including data for the surface microlayer(SML) ,subsurface layer(SSL) and surface layer(SL) . The carbon fluxes across the air-sea interface were calculated. The results showed that the pCO2 values in the surface waters of the study area decreased in the following order:pCO2 SML> pCO2 SSL> pCO2 SL. The highest values were found in March for all SML,SSL and SL,followed by those in April,and the lowest were in May. The pCO2 values had a significant positive correlation with temperature or salinity. While there was no relationship between pCO2 and longitude,there was a significant negative correlation between it and latitude,i.e.,'high latitude low pCO2'. By using four calculation models,the carbon dioxide fluxes(FC O2) in spring in the Yellow and South China Seas,which were found to act as a 'sink' of atmospheric CO2,were preliminarily estimated on the basis of the pCO2 data in the SML to be -7.00×106 t C and -22.35×106 t C,respectively. It is suggested that the FC O2calculated on the basis of pCO2 data in the SML is more reliable than that calculated on the basis of those in the SL.
文摘The effects of fertilizers and water content on N2O emission were studied using the three most typical plantation soils. Soil incubations were performed and fertilization and water content treatments were designed. At 25% of saturated water content（SWC）, N2O emissions from the soil treated with urea, KNO3, （NH4）2 SO, and KH2 PO, were compared at application rates of 0, 100, 200, 300 and 500 kg/hm2. At 80% of SWC, similar experiments were carried out but at only one application rate（500 kg/hm^2）. N2O emissions at various water contents（20%, 35%, 50%, 65%, 80% and 100% of SWC） were studied. At low water content（25% of SWC）, neither nitrogen nor phosphorus（or potassium） fertilizers led to a high level of N2O emission, which generally ranged from 2.03 to 29.02 μg/（m^2·h）. However, at high water content（80% SWC）, the fertilizers resulted in much greater N2O emission irregardless of soil tested. The highest N2O emission rates after 24 h of water addition were 1233 lag/（ m^2 ·h） for S. superba soil, 1507 lag/（m^2 · h） for P. elliottii soil and 1869 lag/ （m^2 h） for A. mangium soil respectively. N2O emission from soils treated with urea, （NH4）2SO, and KH2PO, immediately dropped to a low level but steadily increased to a very high level for the soil treated with KNO3. High NO3^- content was a basis of high level of N2O emission. N2O emission rates from soils peaked shortly after flooding, rapidly dropping to a very low level in soil from non-legume plantations, but lasting for a relatively long period in soil from legume plantations. When soil water content increased equaling to or higher than 65%, the accumulated N2O emission over a period of 13 d ranged from 20.21-29.78 mg/m^2 for S. superba, 30.57-70.12 mg/m^2 for P. elliottii and 300.89-430.51 mg/m^2 for A. mangium. The critical water content was 50% of SWC, above which a high level of N2O emission could be expected, and below which very little N2O emissions were detected. The results suggest that, at low water content（ 〈 50% of SWC）, the fertilization practice is safe with regard to N2O emissions, but at high water content（ 〉 50% of SWC）, nitrogen fertilizer in the form of nitrate could yield a 100-fold increase in N2O emissions. Legume plantations like A. mangium should be avoided in low lands which could easily suffer from flooding or poor drainage.
基金the National Natural Science Foundation of China(Nos.41906188,41806057,41776081)the National Marine Geology Project of China(Nos.DD20160147,DD20190365)+1 种基金the National Program on Global Change and Air-Sea Interaction(No.GASI-GEOGE-02)the Special Fund for the Taishan Scholar Program of Shandong Province(No.ts201511061)。
文摘The South Yellow Sea Basin(SYSB) has multiple sets of proven source rocks and good hydrocarbon prospects,but no industrial oil and gas has been explored at present.To solve this puzzle for petroleum geologists,we systematically investigated the marine hydrocarbon geological conditions based on cores and testing data from borehole CSDP-2,the first exploration well with continuous coring in SYSB.The qualities of source rocks are evaluated in detail according to organic matter abundance,type,and maturity.The reservoir characterization mainly includes porosity,permeability,and reservoir space.Displacement pressure test and stratum thickness are the main foundations for defining the caprocks.Then,the oil-source rock correlation in the Permian and stratum model are analyzed to determine the favorable source-reservoir-caprock assemblages.The results show that three sets of effective source rocks(the Lower Triassic,Upper Permian,and Lower Permian),two sets of tight sandstone re servoirs(the Upper Permian and Lower Silurian-Upper Devonian),and two sets of caprocks(the Lower Triassic and Carboniferous) combine to constitute the hydrocarbon reservoir-forming as se mblages of "lower-ge neration and upper-accumlation" and "self-generation and self-accumlation",thus laying a solid foundation for promising petroleum prospects.The three sets of marine source rocks are characterized by successive generation and expulsion stages,which guarantees multistage hydrocarbon accumulation.Another three sets of continental source rocks distributed across the Middle Jurassic,Upper Cretaceous,and Paleogene depression areas,especially in the Northern Depression,may supplement some hydrocarbons for the Central Uplift through faults and the Indosinian unconformity.The favorable Permian exploration strata have been identified in the Central Uplift of SYSB.First,the Lower Permian and Upper Permian source rocks with high organic matter abundance and high thermal maturity supply sufficient hydrocarbons.Secondly,the interbedding relationship between the source rocks and sandstones in the Upper Permian strata ensures that hydrocarbons have been migrated into the nearby Upper Permian sandstones,reflecting near-source hydrocarbon accumulation.Finally,the good sealing property of the Lower Triassic Qinglong Formation caprocks plays an indispensable role in hydrocarbon preservation of the Permian reservoirs.This conclusion is supported by direct oil shows,gas logging anomalous layers,and hydrocarbon-bearing fluid inclusions.
基金The National Key Research and Development Program of China under contract No.2016YFC1401605the Strategic Priority Research Program of the Chinese Academy of Sciences under contract No.XDA 1102010403+1 种基金the National Natural Science Foundation of China under contract Nos 41222038,41206023 and 41406036the Guangdong Provincial Key Laboratory of Fishery Ecology and Environment under contract No.LFE-2015-3
文摘Marginal seas play important roles in regulating the global carbon budget, but there are great uncertainties in estimating carbon sources and sinks in the continental margins. A Pacific basin-wide physical-biogeochemical model is used to estimate primary productivity and air-sea CO_2 flux in the South China Sea（SCS）, the East China Sea（ECS）, and the Yellow Sea（YS）. The model is forced with daily air-sea fluxes which are derived from the NCEP2 reanalysis from 1982 to 2005. During the period of time, the modeled monthly-mean air-sea CO_2 fluxes in these three marginal seas altered from an atmospheric carbon sink in winter to a source in summer. On annualmean basis, the SCS acts as a source of carbon to the atmosphere（16 Tg/a, calculated by carbon, released to the atmosphere）, and the ECS and the YS are sinks for atmospheric carbon（–6.73 Tg/a and –5.23 Tg/a, respectively,absorbed by the ocean）. The model results suggest that the sea surface temperature（SST） controls the spatial and temporal variations of the oceanic pCO_2 in the SCS and ECS, and biological removal of carbon plays a compensating role in modulating the variability of the oceanic pCO_2 and determining its strength in each sea,especially in the ECS and the SCS. However, the biological activity is the dominating factor for controlling the oceanic pCO_2 in the YS. The modeled depth-integrated primary production（IPP） over the euphotic zone shows seasonal variation features with annual-mean values of 293, 297, and 315 mg/（m^2·d） in the SCS, the ECS, and the YS, respectively. The model-integrated annual-mean new production（uptake of nitrate） values, as in carbon units, are 103, 109, and 139 mg/（m^2·d）, which yield the f-ratios of 0.35, 0.37, and 0.45 for the SCS, the ECS, and the YS, respectively. Compared to the productivity in the ECS and the YS, the seasonal variation of biological productivity in the SCS is rather weak. The atmospheric pCO_2 increases from 1982 to 2005, which is consistent with the anthropogenic CO_2 input to the atmosphere. The oceanic pCO_2 increases in responses to the atmospheric pCO_2 that drives air-sea CO_2 flux in the model. The modeled increase rate of oceanic pCO_2 is0.91 μatm/a in the YS, 1.04 μatm/a in the ECS, and 1.66 μatm/a in the SCS, respectively.
文摘In order to understand the water mass exchange between the South China Sea and the West PhilippineSea, and to study the dissolved carbonate system in the seas surrounding Taiwan Island, we participated in five WOCEcruises (Cruises 257, 262, 266, 287 and 316) aboard R/V Ocean Researcher 1. The areas studied were the South ChinaSea, the West Philippine Sea and the Bashi Channel. Temperature, salinity, pH, alkalinity and total CO2 were measured.Our data indicate that because of the interference of the submarine topography and the Kuroshio axis, there existsa 'front' south of the Lanyu Islet. East of it, the water mass belongs to the West Philippine Sea, on the west in themixed water of the South China Sea and the West Philippine Sea.The South China Sea deep water should have the characteristics similar to the water at about 2 200 m in the WestPhilippine Sea. The calculated results from the residence time, the inorganic carbon dissolution rate and the organic carbon decomposition rate show that the differences between these two water masses should be between 0. 008～0. 023 inpH, 5. 2～15. 0 μmol/kg in apparent oxygen utilization, 3. 6～10. 2 μmol/kg in alkalinity and 6. 4～18. 4 μmol/kg intotal CO2, respectively. The measured results show that there are no distinguishable differences between these two watermasses, implying a short deep water residence time of approximately 40 a.The anthropogenic CO2 penetrates to roughly 500 m, slightly shallower than found in the West Philippine Sea. Theentire South China Sea contains (0. 38±0. 1 ) × 1015 g excess CO2.
文摘The large-scale upper oceanic circulation in the South China Sea (SCS) during the northeast monsoon was investigited using a 2 1/2-layer model inrolving entrainment and detraininent at the interface between the upper mixed layer and the seasonal thermocline. The model allows heat fluxes at the surface and at the interfaee with a reaxation scheme, the temperatures of the two active layers can vary. The model basin is idenical to the SCS lateral boundary with bottom topography of 50 m or more and is regarded as an enclosed basin by neglecting inflow and outflow through the straits, and is forced by the climetological wind stna of 12 calendar months. It was found tha the upper oceanic currents in winter were mainly wind-driven. Most aspects of streams reported by observations were simulated with eddyresolving.
基金The National Natural Science Foundation of China under contract No.41806048the Open Fund of the Hubei Key Laboratory of Marine Geological Resources under contract No.MGR202009+2 种基金the Fund from the Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resource,Institute of Geology,Chinese Academy of Geological Sciences under contract No.J1901-16the Aoshan Science and Technology Innovation Project of Pilot National Laboratory for Marine Science and Technology(Qingdao)under contract No.2015ASKJ03-Seabed Resourcesthe Fund from the Korea Institute of Ocean Science and Technology(KIOST)under contract No.PE99741.
文摘The South Yellow Sea basin is filled with Mesozoic-Cenozoic continental sediments overlying pre-Palaeozoic and Mesozoic-Palaeozoic marine sediments.Conventional multi-channel seismic data cannot describe the velocity structure of the marine residual basin in detail,leading to the lack of a deeper understanding of the distribution and lithology owing to strong energy shielding on the top interface of marine sediments.In this study,we present seismic tomography data from ocean bottom seismographs that describe the NEE-trending velocity distributions of the basin.The results indicate that strong velocity variations occur at shallow crustal levels.Horizontal velocity bodies show good correlation with surface geological features,and multi-layer features exist in the vertical velocity framework(depth:0–10 km).The analyses of the velocity model,gravity data,magnetic data,multichannel seismic profiles,and drilling data showed that high-velocity anomalies(>6.5 km/s)of small(thickness:1–2 km)and large(thickness:>5 km)scales were caused by igneous complexes in the multi-layer structure,which were active during the Palaeogene.Possible locations of good Mesozoic and Palaeozoic marine strata are limited to the Central Uplift and the western part of the Northern Depression along the wide-angle ocean bottom seismograph array.Following the Indosinian movement,a strong compression existed in the Northern Depression during the extensional phase that caused the formation of folds in the middle of the survey line.This study is useful for reconstructing the regional tectonic evolution and delineating the distribution of the marine residual basin in the South Yellow Sea basin.
基金funded by the Na-tional Natural Science Foundation of China[grant number 42005117]the Strategic Priority Research Program of the Chinese Academy of Sciences[grant number XDB40030205]the Key Special Project for the Introducing Talents Team of the Southern Marine Science and Engineering Guangdong Laboratory(Guangdong)[grant number GML2019ZD0601]。
文摘The monthly prediction skill for tropical cyclone(TC)activity in the South China Sea(SCS)during the typhoon season(July to November)was evaluated using the FGOALS-f2 ensemble prediction system.Specifically,the prediction skill of the system at a 10-day lead time for monthly TC activity is given based on 35-year(1981–2015)hindcasts with 24 ensemble members.The results show that FGOALS-f2 can capture the climatology of TC track densities in each month,but there is a delay in the monthly southward movement in the area of high track densities of TCs.The temporal correlation coefficient of TC frequency fluctuates across the different months,among which the highest appears in October(0.59)and the lowest in August(0.30).The rank correlation coefficients of TC track densities are relatively higher(R>0.6)in July,September,and November,while those in August and October are relatively lower(R within 0.2 to 0.6).For real-time prediction of TCs in 2020(July to November),FGOALS-f2 demonstrates a skillful probabilistic prediction of TC genesis and movement.Besides,the system successfully forecasts the correct sign of monthly anomalies of TC frequency and accumulated cyclone energy for 2020(July to November)in the SCS.
基金jointly supported by the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2020B0301030004)the National Natural Science Foundation of China(Grant Nos.42088101,41975074 and 42175023)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA20100304)the Second Comprehensive Scientific Investigation on the Tibetan Plateau of China(2019QZKK0208)the Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies(Grant No.2020B1212060025)。
文摘This study depicts the sub-seasonal prediction of the South China Sea summer monsoon onset(SCSSMO)and investigates the associated oceanic and atmospheric processes,utilizing the hindcasts of the National Centers for Environmental Prediction(NCEP)Climate Forecast System version 2(CFSv2).Typically,the SCSSMO is accompanied by an eastward retreat of the western North Pacific subtropical high(WNPSH),development of the cross-equatorial flow,and an increase in the east-west sea surface temperature(SST)gradient.These features are favorable for the onset of westerlies and strengthening of convection and precipitation over the South China Sea(SCS).A more vigorous SCSSMO process shows a higher predictability,and vice versa.The NCEP CFSv2 can successfully predict the onset date and evolution of the monsoon about 4 pentads(20 days)in advance(within 1–2 pentads)for more forceful(less vigorous)SCSSMO processes.On the other hand,the climatological SCSSMO that occurs around the 27th pentad can be accurately predicted in one pentad,and the predicted SCSSMO occurs 1–2 pentads earlier than the observed with a weaker intensity at longer leadtimes.Warm SST biases appear over the western equatorial Pacific preceding the SCSSMO.These biases induce a weaker-thanobserved WNPSH as a Gill-type response,leading to weakened low-level easterlies over the SCS and hence an earlier and less vigorous SCSSMO.In addition,after the SCSSMO,remarkable warm biases over the eastern Indian Ocean and the SCS and cold biases over the WNP induce weaker-than-observed westerlies over the SCS,thus also contributing to the less vigorous SCSSMO.
