We conducted a field campaign to investigate the chemical composition,sources,and light absorption of submicron aerosols(PM_(1))from early 2022 in Nanjing,China.The average concentration of PM_(1) was 31μg m^(−3),org...We conducted a field campaign to investigate the chemical composition,sources,and light absorption of submicron aerosols(PM_(1))from early 2022 in Nanjing,China.The average concentration of PM_(1) was 31μg m^(−3),organics(33%)constituted the largest fraction,followed by nitrate(30%),sulfate(18%),ammonium(15%),chloride(3%),and rBC(2%).Four organic aerosol(OA)subcomponents were identified,including two primary OA(POA)and two secondary OA(SOA).The less-oxidized SOA(LO-OOA)contributes the most to the total OA mass(59%).LO-OOA is tightly correlated with the tracer ion C_(2)H_(4)O_(2)^(+)from levoglucosan,and another aged biomass-burning derived species,K_(3)SO_(4)^(+),suggesting it was likely influenced by aged biomass-burning OA.Our study also revealed that fireworks during the Spring Festival have a detrimental impact on air quality,contributing to secondary formation and accumulation under static winter meteorological conditions,prolonging the pollution duration.Also,LO-OOA was found to have the strongest light-absorbing ability.Our results highlight that the light absorption of LO-OOA can mainly be attributed to the C_(x)H_(y)N^(+) family,increased with the double-bond equivalent value.The more-oxidized SOA(MO-OOA)exhibited a negligible light absorption and was strongly correlated with daytime photochemical processes,implying a light-bleaching effect.This study enhances our understanding of the regional contribution of biomass combustion and fireworks to PM_(1) pollution in Nanjing,a typical megacity in the Yangtze River Delta region,during winter,aiding in the development of strategies for long-term air quality improvement in the region.展开更多
Climate change caused by carbon emissions is a hot topic of concern.Enhancing carbon emission performance(CEP)emerges as a pivotal strategy to curtail carbon emissions,with the digital economy recognized as a crucial ...Climate change caused by carbon emissions is a hot topic of concern.Enhancing carbon emission performance(CEP)emerges as a pivotal strategy to curtail carbon emissions,with the digital economy recognized as a crucial instrument for bolstering CEP.Grounded in theoretical analysis,this article takes the Yangtze River Delta region(YRD)as the research object and conducts empirical analysis for the period from 2010 to 2021.The Super Epsilon-Based Measure(EBM)model was employed to assess CEP,while the entropy method was used to quantify the level of the digital economy.Baseline regression models and mediation effect models were constructed to test the research hypotheses.Additionally,the Spatial Durbin Model(SDM)was utilized to analyze the spatial spillover effects of the digital economy.Some conclusions were drawn as follows.Firstly,both the digital economy and CEP exhibit growing trends and demonstrate significant spatial distribution characteristics.Cities with high CEP are increasingly concentrated along the Yangtze River and coastal areas.Meanwhile,the digital economy generally demonstrates a spatial distribution pattern of being higher in the southeast and lower in the northwest.Secondly,the digital economy exerts a notable and consistent positive influence on CEP,but this impact is not primarily achieved through promoting green technology innovation.Instead,the digital economy exhibits a stronger intermediary effect on CEP by facilitating industrial structure upgrading and rationalization.Thirdly,the digital economy significantly enhancing local CEP but having an insignificant impact on neighboring cities'CEP.To address these findings,cities ought to invest in digital infrastructure,incentivize digital innovation through policy and financial backing,and harness advanced technologies like 5G and blockchain to promote low-carbon,intelligent production and lifestyles,while enhancing industrial structure and regional cooperation to foster a low-carbon digital economy network.展开更多
A macro-tidal tropical estuary with high fluvial discharge is characterized by both fragility and remarkable dynamism.This study utilizes the Salween River Delta(SRD)as a case example to examine the interplay between ...A macro-tidal tropical estuary with high fluvial discharge is characterized by both fragility and remarkable dynamism.This study utilizes the Salween River Delta(SRD)as a case example to examine the interplay between morphology and vegetation under similar tidal conditions.Our analysis of correlations and inferences revealed several significant trends in the SRD:(1)an overall expansion of land area and intertidal vegetation,with the most pronounced changes occurring in the eastern sector;(2)the predominance of river discharge influencing the southwestern and northern sectors,contrasted with the primary impact of storm surges in the eastern sector;and(3)three distinct causal relationships among estuarine morphology,vegetation,storm surges,and river discharge:a direct model where river discharge shapes estuarine morphology,a progressive model in which river discharge affects vegetation distribution,subsequently influencing estuarine morphology,and a hybrid model where storm surges directly impact vegetation and indirectly modify its distribution through changes in estuarine morphology.The stability of sediment supply and the role of intertidal vegetation are crucial for the continuous seaward advance,providing a vital foundation for the protection and development of estuarine deltas.展开更多
Scientifically understanding the evolution of urbanization and analysing the coupling mechanism of human-land systems are important foundations for solving spatial conflicts and promoting regional sustainable developm...Scientifically understanding the evolution of urbanization and analysing the coupling mechanism of human-land systems are important foundations for solving spatial conflicts and promoting regional sustainable development.This study analyzed the spatiotemporal evolution and landscape pattern change of construction land in the Yangtze River Delta(YRD)region from 1990 to 2018 by integrating Geographical Information System(GIS)spatial analysis and landscape pattern indices,and revealed its driving mechanism by XGBoost and SHapley Additive ex Planations(SHAP).Moreover,we compared the disparities in the core driving factors for construction land evolution in cities with diverse development orientations within the YRD region.Results show that:1)development intensity of construction land continued to increase from 7.54%in 1990 to 13.44%in 2018,primarily by occupying farmland.The landscape fragmentation of construction land in the YRD region decreased,and landscape dominance increased.Spatially,the eastern part of the YRD exhibits a high degree of spatial agglomeration of construction land,whereas the western part shows a high degree of fragmentation,revealing distinct spatial gradient differentiation characteristics.The landscape dominance of the construction land in the eastern region of the YRD is higher than that in the western and northern regions.2)Transportation and infrastructure exert the highest contribution rate on development intensity changes of construction land in the YRD.The industrial structure significantly influences the conversion of farmland to construction land.Additionally,infrastructure plays a crucial role in shaping the spatial agglomeration patterns of construction land.Population distribution is the dominant factor determining the regularity of the landscape shape of construction land.3)The core driving factors for the development intensity of construction land in central cities primarily lies in transportation,whereas for non-central cities,besides transportation,the year-end balance of per capita savings deposits of urban and rural residents also play a significant role.The area change of construction land occupying farmland in central and non-central cities is mainly driven by industrial structure and economic level,respectively.This study informs refined spatial optimization and regional high-quality integrated development.展开更多
This study focuses on the spatiotemporal distribution,urban-rural variations,and driving factors of ammonia Vertical Column Densities(VCDs)in China’s Yangtze River Delta region(YRD)from 2008 to 2020.Utilizing data fr...This study focuses on the spatiotemporal distribution,urban-rural variations,and driving factors of ammonia Vertical Column Densities(VCDs)in China’s Yangtze River Delta region(YRD)from 2008 to 2020.Utilizing data from the Infrared Atmospheric Sounding Interfer-ometer(IASI),Generalized Additive Models(GAM),and the GEOS-Chem chemical transport model,we observed a significant increase of NH_(3)VCDs in the YRD between 2014 and 2020.The spatial distribution analysis revealed higher NH_(3)concentrations in the northern part of the YRD region,primarily due to lower precipitation,alkaline soil,and intensive agricul-tural activities.NH_(3)VCDs in the YRD region increased significantly(65.18%)from 2008 to 2020.The highest growth rate occurs in the summer,with an annual average growth rate of 7.2%during the period from 2014 to 2020.Agricultural emissions dominated NH_(3)VCDs during spring and summer,with high concentrations primarily located in the agricultural areas adjacent to densely populated urban zones.Regions within several large urban areas have been discovered to exhibit relatively stable variations in NH_(3)VCDs.The rise in NH_(3)VCDs within the YRD region was primarily driven by the reduction of acidic gases like SO_(2),as emphasized by GAM modeling and sensitivity tests using the GEOS-Chem model.The concentration changes of acidic gases contribute to over 80%of the interannual variations in NH_(3)VCDs.This emphasizes the crucial role of environmental policies targeting the reduction of these acidic gases.Effective emission control is urgent tomitigate environmental hazards and secondary particulate matter,especially in the northern YRD.展开更多
Extensive spatiotemporal analyses of long-trend surface ozone in the Yangtze River Delta(YRD)region and itsmeteorology-related and emission-related have not been systematically analyzed.In this study,by using 8-year-l...Extensive spatiotemporal analyses of long-trend surface ozone in the Yangtze River Delta(YRD)region and itsmeteorology-related and emission-related have not been systematically analyzed.In this study,by using 8-year-long(2015–2022)surface ozone observation data,we attempted to reveal the variation ofmultiple timescale components using the Kolmogorov–Zurbenko filter,and the effects of meteorology and emissions were quantitatively isolated using multiple linear regression with meteorological variables.The results showed that the short-term,seasonal,and long-term components accounted for daily maximum 8-hr average O_(3)(O_(3–8)hr)concentration,46.4%,45.9%,and 1.0%,respectively.The meteorological impacts account for an average of 71.8%of O_(3–8)hr,and the YRD’s eastern and northern sections aremeteorology-sensitive areas.Based on statistical analysis technology with empirical orthogonal function,the contribution of meteorology,local emission,and transport in the long-term component of O_(3–8)hr were 0.21%,0.12%,and 0.6%,respectively.The spatiotemporal analysis indicated that a distinct decreasing spatial pattern could be observed from coastal cities towards the northwest,influenced by the monsoon and synoptic conditions.The central urban agglomeration north and south of the YRD was particularly susceptible to local pollution.Among the cities studied,Shanghai,Anqing,and Xuancheng,located at similar latitudes,were significantly impacted by atmospheric transmission—the contribution of Shanghai,the maximum accounting for 3.6%.展开更多
Agricultural production(especially intensive rice production)is a primary income source for over 2.0×10^(7) people in the Vietnamese Mekong River Delta.However,adverse climate change impacts,socio-economic change...Agricultural production(especially intensive rice production)is a primary income source for over 2.0×10^(7) people in the Vietnamese Mekong River Delta.However,adverse climate change impacts,socio-economic change,and high dependence on farm inputs for intensive production constrain the longer-term sustainability of rice systems.Government and agribusiness actors are encouraging more farmers to grow non-rice crops and supporting the upscaling of alternative crops to paddy rice.We used a qualitative approach to investigate the value chain characteristics,as well as constraints and opportunities of alternative crops via two case studies(baby corn and honeydew melon)in An Giang and Hau Giang provinces,Vietnam.Data collection involved focus group discussions with local farmers and interviews with farmers and industry experts.Thematic analysis was used to compile the findings,and the results were validated with local government staff.The baby corn value chain featured on-going and stable market demand(including value-addition)and better vertical coordination(e.g.,written contracts and financial support).The honeydew melon value chain featured positive relationships between farmers and traders despite less-developed vertical coordination.There are opportunities for value chain engagement through product quality certification,value-addition,and accessing high-value domestic and export markets.However,farmers require crop-specific and generic support from private and public sectors.Increased labour requirements and limited access to finance and credit limit value chain participation.Upscaling and marketing alternative crops can enhance farmer profitability and support non-farming agricultural business establishment,economic growth,and community development.Efficient value chains will be critical to ensure the adoption of alternative crops and development of crop-specific agribusiness models.These findings can inform policy-makers and change facilitators in designing targeted interventions to support the adoption of alternative crops in the study area as well as in Vietnam and globally.展开更多
Urban lakes are vital components of the modern urban water system and landscape design.They play an important role in the construction of urban ecological civilization.However,in recent years,the urban lake ecosystem ...Urban lakes are vital components of the modern urban water system and landscape design.They play an important role in the construction of urban ecological civilization.However,in recent years,the urban lake ecosystem has been increasingly degraded,especially with the frequent cyanobacteria blooms,which directly threatens the maintenance of ecosystem service function and sustainable urban development.In this study,several sedimentary cores were collected from Hudie Lake located in the Yangtze River Delta in China that had not been dredged for centuries.Using one of the sediment cores that spans the past 200 years,we reconstructed the long-term environmental changes and examined the driving mechanisms of both human activities and natural factors affecting the lake's dynamics.Our results indicated that,with the growth of the city,organic matter and nutrients in the lake had gradually increased.Notably,the significant increase in phosphorus had been a key factor driving cyanobacteria blooms in Hudie Lake.Since the 1960s,urban development and changes in land use around the lake had severely disturbed its natural habitats,leading to peak nutrient levels during the period from 2000 to 2010.展开更多
Digital transformation,as a recent trend in socioeconomic development,is considered as a critical pathway for urban carbon reduction because of its potential to increase productivity and energy efficiency.However,few ...Digital transformation,as a recent trend in socioeconomic development,is considered as a critical pathway for urban carbon reduction because of its potential to increase productivity and energy efficiency.However,few studies have explored the relationship between urban digitalization and carbon emissions(CE).Therefore,this study systematically analyzed the spatiotemporal distribution and interaction mechanism between digitalization and CE in the Yangtze River Delta(YRD)urban agglomerations of China during 2006-2020 based on a multidimensional indicator system,including digitalization industry level,digitalization application level,and urban green digitalization willingness.The findings revealed that both digitalization and CE in the YRD exhibit a significant and synchronously evolving“core-periphery”spatial pattern.Core cities generated substantial positive spillover effect on periphery cities through technology diffusion and policy demonstration,advancing both regional digitalization and the collaborative governance of CE.However,digitalization had dual impact on CE.On the one hand,it promoted the reduction of CE by enhancing energy efficiency,optimizing industrial structures,and promoting the application of green technologies.On the other hand,the expansion of digital infrastructure introduced a potential risk of increased energy consumption.Therefore,targeted policy recommendations are proposed to facilitate the coordination of environmental sustainability and digitalization in the YRD.This study provides empirical support and policy insights for advancing the coordinated development of regional digital transformation and green low-carbon initiatives.展开更多
Organic amine pesticides(OAPs)are widely used in modern agriculture and these compounds can contaminate drinking water sources in different ways.However,there is a lack of data on the occurrence of OAPs in drinking wa...Organic amine pesticides(OAPs)are widely used in modern agriculture and these compounds can contaminate drinking water sources in different ways.However,there is a lack of data on the occurrence of OAPs in drinking water and their potential human health risks.In this study,tapwater(TW)and bottledwater(BW)sampleswere collected from eight cities in the Yangtze River Delta urban agglomeration in China,and their OAP levelswere analyzed using high-throughput organic analysis testing coupled with high-volume solid-phase extraction(Hi-throat/Hi-volume SPE techniques).This study is the first to systematically characterize the trace levels of OAPs in drinking water in China.Our findings indicated that the total concentration of OAPs(OAPs)in TW(average 11.06±4.99 ng/L)was 29.4%higher than in BW(average 8.55±3.98 ng/L)and fewer kinds(7)of OAPs were detected in BW.Furthermore,the long-term intake of TW in some areas was linked to carcinogenic risks even at an acceptable OAP range,particularly in males,with molinate being the major contributor(61.3%)to OAP exposure.Further analysis revealed that the occurrence and health risks of OAPs in drinking water were mainly influenced by the quality of water sources and the technologies adopted in drinking water treatment plants(DWTPs).Furthermore,our findings demonstrated that advanced treatment technologies such as nanofiltration could more effectively remove OAPs in raw water(up to 87.5%).Therefore,our findings highlighted the importance of selecting appropriate advanced treatment technologies in DWTPs.展开更多
The Yellow River Delta(YRD)of China is one of the most active land-sea interaction deltas in the world.However,due to human activities and climate change,it has undergone significant changes,including the degradation ...The Yellow River Delta(YRD)of China is one of the most active land-sea interaction deltas in the world.However,due to human activities and climate change,it has undergone significant changes,including the degradation of natural wetlands and saltwater intrusion.As an integral part of soil microorganisms,fungi play a crucial role in maintaining and stabilizing the function of wetland ecosystems.To better understand the composition and diversity changes of fungal communities along a salinity gradient in the YRD of China and their relationship with environmental factors,fungal diversity,abundance,and composition in the sediments of four typical vegetation communities spanning from the riverbank to the seaside were investigated.The results showed that the electrical conductivity(EC)increased significantly from the riverbank to the coastal area(P<0.05),but the levels of total nitrogen(TN),total carbon(TC),total sulfur(TS),available phosphorous(AP),and ammonium(NH_(4)^(+)-N)increased in Phragmites australis community and then experienced a significant decrease in Tamarix chinensis community and Suaeda salsa community(P<0.05).The alpha diversity(Shannon and Simpson indices)of the soil fungal community exhibited a negative correlation with EC.There was a significant alteration in the structure of the fungal community,primarily influenced by EC and NO_(3)^(-)-N.Ascomycota was found to be the most abundant phylum,and its relative abundance is positively correlated with pH and TS.The relative abundance of Sordariomycetes,the second-largest class of Ascomycota,reached 38.95%.Salinity was identified as the most important factor driving changes in soil fungal community composition.In summary,the fungal community changed significantly along the salinity gradient,and different environmental factors impacted various tiers of fungal populations differently.The findings of this study lay the groundwork for comprehending soil fungal communities and their primary influencing factors in newly formed wetlands.展开更多
The Yellow River Delta(YRD)is rich in oil,natural gas,and land resources.With the expansion of an important oil production base in North China,the increased discharge of Polycyclic aromatic hydrocarbons(PAHs)and alkyl...The Yellow River Delta(YRD)is rich in oil,natural gas,and land resources.With the expansion of an important oil production base in North China,the increased discharge of Polycyclic aromatic hydrocarbons(PAHs)and alkylated/nitrated/oxygenated PAHs(APAHs/NPAHs/OPAHs)into the Yellow River poses a potential risk to the aquatic ecosystem and human health.A total of 42 samples were gathered from trunk streams and tributaries within the YRD region during the wet and dry seasons,and 19 PAHs,5 APAHs,16 NPAHs,and 7 OPAHswere measured.The concentrations of ƩPAHs,ƩAPAHs,ƩNPAHs and ƩOPAHs ranged between 29 and 620 ng/L,6.9–81 ng/L,0.64–9.0 ng/L,and 7.2–81 ng/L in water,respectively,and 27–420 ng/g,5.1–130 ng/g,0.19–1.8 ng/g and 3.9–51 ng/g in sediment,respectively.The oil extraction activities resulted in an increased presence of middle-high molecular weight PAHs and APAHs in sediment,and port activities had a notable influence on the proportion of 1-methylpyrene in both water and sediment.The fugacity fraction analysis suggested that sediment was a secondary source of OPAHs,while benzo[k]fluoranthene,benzo[e]pyrene,benzo[a]pyrene,and 5-methylchrysene migrated from water to sediment.The main contributors to PAHs,APAHs,NPAHs,and OPAHs in water and sediment were combustion and petroleum sources.Compared to water,sediment displayed a heightened ecological risk associated with PAHs,APAHs,NPAHs,and OPAHs.Adults residing in the YRD region were at higher risk of cancer than children,which deserves special attention.展开更多
The Pearl River Delta(PRD)region has been identified as a significant hotspot of wet ammonium deposition.However,the absence of long-term monitoring data in the area hinders the comprehension of the historical trends ...The Pearl River Delta(PRD)region has been identified as a significant hotspot of wet ammonium deposition.However,the absence of long-term monitoring data in the area hinders the comprehension of the historical trends and changes in wet NH_(4)^(+)-N deposition in response to emissions,which interferes with the ability to make effective decisions.This study has analyzed the long-term trends of wet NH_(4)^(+)-N deposition flux and has quantified the effect of anthropogenic emissions and meteorological factors at a typical urban site and a typical forest site in the PRD region from 2009 to 2020.It revealed a significant decreasing trend in wet NH_(4)^(+)-N flux in both the typical urban and forest areas of the PRD region,at-6.2%/year(p<0.001)and-3.3%/year(p<0.001),respectively.Anthropogenic emissions are thought to have contributed 47%–57%of the wet NH_(4)^(+)-N deposition trend over the past 12 years compared to meteorological factors.Meteorological conditions dominated the interannual fluctuations in wet NH_(4)^(+)-N deposition with an absolute contribution of 46%–52%,while anthropogenic emissions change alone explained 10%–31%.NH_(3)emissions have the greatest impact on the urban area among anthropogenic emission factors,while SO_(2)emissions have the greatest impact on the forest area.Additionally,precipitation was identified as the primary meteorological driver for both sites.Our findings also imply that the benefits of NH_(3)emissions reductions might not immediately emerge due to interference from weather-related factors.展开更多
The perfection of the cross-border regional innovation system of the Pearl River Delta(PRD)and Hong Kong region remarkably underpins the construction of the Guangdong-Hong Kong-Macao Greater Bay Area(GBA)towards an in...The perfection of the cross-border regional innovation system of the Pearl River Delta(PRD)and Hong Kong region remarkably underpins the construction of the Guangdong-Hong Kong-Macao Greater Bay Area(GBA)towards an international technological innovation hub.This paper focuses on the relational characteristics of the usage of technological innovation functions and elements,including labor force,technology,and producer services from Hong Kong region by high-technology firms in the PRD,and probes into the influencing factors by integrating the objective perspective on the impact of firm-level socioeconomic attributes and subjective perspective on the open interpretations on the reasons by using or not using technological innovation functions and elements from Hong Kong region by various stakeholders in high-technology domains in the PRD.Key research findings are fourfold.First,Hong Kong's technological innovation functions primarily ride on its institutional advantages under the“One Country,Two Systems”framework to empower high-technology firms in the PRD by expanding their international market,international business operation,and financing,but cross-border investment and entrepreneurship has retrieved to a relatively marginalized position.The degree of supply-demand relations of producer services is the highest,followed by labor force and technology.Second,Hong Kong-invested,large-sized,and long-standing high-technology firms in the PRD are more inclined to use technological innovation elements from Hong Kong region,while domestic,small-and-medium-sized,and start-up high-technology firms in the PRD are in turn,gradually unhooked from the supply of technological innovation elements from Hong Kong region.Third,Hong Kong enjoys both advantages and disadvantages in supplying labor forces,technologies,and producer services to high-technology firms in the PRD,with advantages in competitiveness,international linkages and visions,and disadvantages in high cost,lack of more profound mutual understanding between Hong Kong and the PRD,and the imperfect cooperation mechanisms.Fourth,interactions among the transitioning role of Hong Kong region in the macro-level global and national economic development landscape,meso-level cross-border regional specificities under the“One Country,Two Systems”framework,and micro-level heterogeneous practices and capabilities of firms influence the usage of technological innovation functions and elements from Hong Kong region by high-technology firms in the PRD.展开更多
The river plume front between the diluted ocean water and salty ocean water in the Changjiang(Yangtze)River Delta(CRD)is well studied.Comparatively,less is known about the estuarine front in the CRD,which is formed be...The river plume front between the diluted ocean water and salty ocean water in the Changjiang(Yangtze)River Delta(CRD)is well studied.Comparatively,less is known about the estuarine front in the CRD,which is formed between the riverine freshwater and the diluted ocean water and has the highest magnitude of salinity gradient(SG)in the CRD.Estuarine fronts are of great significance to the riverine material transport in the estuary.Many biogeochemical processes are enhanced in estuarine fronts,which have brought about environmental problems.In this study,the seasonal variations of the estuarine fronts in the CRD were studied in wet(July)and dry(January)seasons in 2017,based on model simulations with high spatiotemporal resolutions using the Finite-Volume Community Ocean Model(FVCOM).The estuarine front included several sharp fronts with a SG>4(/500 m),and was bottom-trapped on the submerged delta front.Seasonal changes mainly occurred off the Jiangsu coast,where a significant estuarine front was formed in July.The estuarine fronts generated around the submerged delta topography were accompanied by the offshore extension of older estuarine fronts,which were diluted and evolved into plume fronts over a tidal cycle.The simulated estuarine fronts had a salinity range of 6 to 22 in the dry season and 6 to 14 in wet season 2017.The estuarine fronts hindered the residual current by altering its flow direction to the southeast.展开更多
The historical movements of relative sea level(RSL)reflect the geomorphological dynamics around coastal regions in the past,and reconstructing the RSL curve contributes to the prediction of future RSL movements.On the...The historical movements of relative sea level(RSL)reflect the geomorphological dynamics around coastal regions in the past,and reconstructing the RSL curve contributes to the prediction of future RSL movements.On the basis of the sediment sequence and optical stimulated luminescence(OSL)dating data of three boreholes in the Yellow River Delta(YRD),the positions of paleo-coastlines and the movements of RSL in the last 2000 years were reconstructed.The main results are as follows:1)the YRD coast transformed from a tide-dominated silty coast to a wave-dominated sandy coast and back to a tide-dominated silty coast in the last 2000 years.2)The sand layers consisting of shell fragments indicated the locations of the coastline in 1855 AD,893 AD,and 40 BC,and their top elevations were close to the mean high water level in the corresponding years.3)The mean sea level elevation in 79 BC,1019 AD,and 1800 AD relative to the modern sea level was -4.52,-4.52,and-2.92 m,respectively.4)The RSL was almost stagnant during 79 BC-1019 AD,rose slowly during 1019-1800 AD due to the reverse change of global climate from the Little Ice Age to the Medieval Warm Period,and rose significantly after 1800 AD due to the warm period.5)The movement of RSL controlled the surface slope of YRD,which was a slope of approximately 0.022‰ at 893 AD,an inverted slope of 0.144‰ at 1855 AD,and a slope of 0.075‰ recently.These findings indicate that the modern YRD is far from being abandoned in the future,providing a historical geomorphological basis for the management of the Yellow River Estuary.展开更多
This study examines the degree of urban‒rural integrated development(URID)and its determinants across 41 cities within the YRDR during the period spanning from 2012 to 2021 by employing the entropy weighting method an...This study examines the degree of urban‒rural integrated development(URID)and its determinants across 41 cities within the YRDR during the period spanning from 2012 to 2021 by employing the entropy weighting method and geodetic detector model.The results reveal the following.First,the overall URID in the Yangtze River Delta region(YRDR)accelerated.Cities in the central and eastern parts exhibit a greater URID,which decreases toward the west,north,and south,highlighting prominent developmental imbalances between cities.Second,integrated economic development between urban and rural areas(URAs)has consistently demonstrated superior performance.Social integration in URA has exhibited a steady upward trajectory,whereas the integration and improvement of urban and rural residents'quality of life have advanced at a comparatively modest pace.Third,the factors that significantly influence the URID within the YRDR include per capita GDP,postal and telecommunication services per capita,and the proportion of private car ownership.Conversely,the impact of governmental intervention and agricultural security appears to be comparatively diminished.Moreover,the combined influence of interacting dual factors surpasses that of individual elements,with the influence gradually stabilizing over time.Ultimately,this study provides policy suggestions to foster integrated urban and rural development in the Yangtze River Delta(YRD)with a focus on regional collaboration and development strategies.展开更多
Under the new development pattern,promoting the balanced development of the regional life service level is the key to attaining the goal of meeting people’s need for an improved life.This study constructed an index s...Under the new development pattern,promoting the balanced development of the regional life service level is the key to attaining the goal of meeting people’s need for an improved life.This study constructed an index system with six dimensions,namely,economic base,innovation drive,living environment,transportation,public services and life security,and explored the balanced characteristics and obstacles of the life service level in the Yangtze River Delta,China in 2020 using the Gini coefficient,the standard deviation ellipse,the global spatial autocorrelation,the equilibrium entropy and the obstacle degree model.Results show that:1)the current overall level of life services in the Yangtze River Delta is in relative equilibrium,and the Gini coefficient of three dimensions,namely,economic base,innovation drive and life security,is relatively low and on the verge of imbalance.2)The spatial pattern of the six dimensions of the overall level of the life service is oriented toward the‘southeast-northwest’direction with significant spatial differentiation and spatial agglomeration.3)At present,most of the cities have a comparative advantage in the coordination of their life services,and the potential of their life service system shows room for further improvement in the future.4)Currently,the quality of economic development,talent concentration,innovation inputs,innovation outputs,basic education,health care,cultural sharing,the living standards of the urban and rural residents and the construction of a transportation system are the main factors constraining the improvement of the level of life services in the Yangtze River Delta.This study attempts to research on the evaluation and measurement of regional life service level in the new era,and provides a reference for the promotion of regional coordination and sustainable development.展开更多
Based on the chemical composition data of a regional long-lasting haze event that occurred in the Yangtze River Delta(YRD)region from 17 December 2023 to 8 January 2024,the evolutionary characteristics of the chemical...Based on the chemical composition data of a regional long-lasting haze event that occurred in the Yangtze River Delta(YRD)region from 17 December 2023 to 8 January 2024,the evolutionary characteristics of the chemical components and sources of fine particulate matter(PM2.5)under different pollution levels were comparatively analyzed using PMF(Positive Matrix Factorization)and backward trajectory analysis.SNA(NO_(3)^(-),NH_(4)^(+),SO_(4)^(2-))was found to be the primary chemical component of PM2.5,making up 63.6%(clean days)to 69.7%(heavy pollution)of it.The NO_(3)^(-)concentration was 3.14(clean days)to 6.01(heavy pollution)times higher than that of SO_(4)^(2-).NO_(3)^(-),POC,Fe,Mn,Al concentrations increased,while SOC,EC,crustal elements(Ca,Si)and other water-soluble ions(WSIs)concentrations decreased as the pollution level increased.The contribution of secondary inorganics and biomass-burning emissions and industrial and ship emissions increased significantly as the pollution level increased,which accounted for 40.3%and 36.7%,respectively,in the heavy pollution stage.The contribution of traffic sources decreases gradually with increasing pollution levels,accounting for only 59.1%of the light pollution stage in the heavy pollution stage.PM_(2.5) and its main chemical components showed similar potential source distribution,located in the northwest(Fuyang,Huainan,Nanjing),south(Taizhou,Lishui,Jiande)and north(Taizhou,Yancheng).However,distinct transport routes were observed under the different air quality levels.During the heavy pollution period,the polluted air masses primarily came from the harbor regions,whereas during the light pollution period they were transported from the southeast(Taizhou)and the North China Plain.展开更多
Accurate mapping of wetlands is crucial for wetlands conservation, as well as for monitoring and assessing coastal resources and the environment. Multispectral(MSI) satellite image time series have rich temporal evolu...Accurate mapping of wetlands is crucial for wetlands conservation, as well as for monitoring and assessing coastal resources and the environment. Multispectral(MSI) satellite image time series have rich temporal evolution characteristics, which can reveal dynamic changes in surface cover and environmental conditions. However, due to the limited number of bands, the ability to express the difference of ground features is limited, resulting in an inability to capture surface objects' changes in the finer spectral range. Therefore,this paper proposed a dual-branch spatial-temporal spectral feature fusion network(Fusion-Former), which combined MSI time series data with hyperspectral(HSI) data to achieve accurate mapping of wetlands in Liaohe River Delta, China in 2022. Fusion-Former achieved an overall accuracy(OA) of 96.36% in the Liaohe River Delta wetland, significantly outperforming all benchmark methods.Experimental results demonstrate that utilizing the temporal phenological information from multi-temporal MSI and the fine-grained spatial-spectral features from HSI can effectively resolve the misclassification between spectrally similar vegetation and water bodies.Furthermore, a continuous improvement in accuracy was observed as the length of the input time series increased, underscoring the critical role of temporal information. Therefore, by integrating these complementary information sources, the proposed method enables the generation of accurate wetland maps to support decision-makers in formulating more precise conservation and management strategies.展开更多
基金support from the Natural Science Foundation of Jiangsu Province(Grant No.BK20240036)the National Natural Science Foundation of China(Grant Nos.U24A20515,22276099,and 22361162668)Guangxi Key Research and Development Program,China(Grant No.Guike AB24010074)。
文摘We conducted a field campaign to investigate the chemical composition,sources,and light absorption of submicron aerosols(PM_(1))from early 2022 in Nanjing,China.The average concentration of PM_(1) was 31μg m^(−3),organics(33%)constituted the largest fraction,followed by nitrate(30%),sulfate(18%),ammonium(15%),chloride(3%),and rBC(2%).Four organic aerosol(OA)subcomponents were identified,including two primary OA(POA)and two secondary OA(SOA).The less-oxidized SOA(LO-OOA)contributes the most to the total OA mass(59%).LO-OOA is tightly correlated with the tracer ion C_(2)H_(4)O_(2)^(+)from levoglucosan,and another aged biomass-burning derived species,K_(3)SO_(4)^(+),suggesting it was likely influenced by aged biomass-burning OA.Our study also revealed that fireworks during the Spring Festival have a detrimental impact on air quality,contributing to secondary formation and accumulation under static winter meteorological conditions,prolonging the pollution duration.Also,LO-OOA was found to have the strongest light-absorbing ability.Our results highlight that the light absorption of LO-OOA can mainly be attributed to the C_(x)H_(y)N^(+) family,increased with the double-bond equivalent value.The more-oxidized SOA(MO-OOA)exhibited a negligible light absorption and was strongly correlated with daytime photochemical processes,implying a light-bleaching effect.This study enhances our understanding of the regional contribution of biomass combustion and fireworks to PM_(1) pollution in Nanjing,a typical megacity in the Yangtze River Delta region,during winter,aiding in the development of strategies for long-term air quality improvement in the region.
基金Under the auspices of the National Natural Science Foundation of China(No.42101164)Major Project of Philosophy and Social Sciences in Colleges and Universities by Jiangsu Province(No.2024SJZD025)。
文摘Climate change caused by carbon emissions is a hot topic of concern.Enhancing carbon emission performance(CEP)emerges as a pivotal strategy to curtail carbon emissions,with the digital economy recognized as a crucial instrument for bolstering CEP.Grounded in theoretical analysis,this article takes the Yangtze River Delta region(YRD)as the research object and conducts empirical analysis for the period from 2010 to 2021.The Super Epsilon-Based Measure(EBM)model was employed to assess CEP,while the entropy method was used to quantify the level of the digital economy.Baseline regression models and mediation effect models were constructed to test the research hypotheses.Additionally,the Spatial Durbin Model(SDM)was utilized to analyze the spatial spillover effects of the digital economy.Some conclusions were drawn as follows.Firstly,both the digital economy and CEP exhibit growing trends and demonstrate significant spatial distribution characteristics.Cities with high CEP are increasingly concentrated along the Yangtze River and coastal areas.Meanwhile,the digital economy generally demonstrates a spatial distribution pattern of being higher in the southeast and lower in the northwest.Secondly,the digital economy exerts a notable and consistent positive influence on CEP,but this impact is not primarily achieved through promoting green technology innovation.Instead,the digital economy exhibits a stronger intermediary effect on CEP by facilitating industrial structure upgrading and rationalization.Thirdly,the digital economy significantly enhancing local CEP but having an insignificant impact on neighboring cities'CEP.To address these findings,cities ought to invest in digital infrastructure,incentivize digital innovation through policy and financial backing,and harness advanced technologies like 5G and blockchain to promote low-carbon,intelligent production and lifestyles,while enhancing industrial structure and regional cooperation to foster a low-carbon digital economy network.
基金National Natural Science Foundation of China,No.41906148,No.42271086Rejuvenating Yunnan Talents Support Plan Young Talent Program,No.XDYC-QNRC-2023-0322。
文摘A macro-tidal tropical estuary with high fluvial discharge is characterized by both fragility and remarkable dynamism.This study utilizes the Salween River Delta(SRD)as a case example to examine the interplay between morphology and vegetation under similar tidal conditions.Our analysis of correlations and inferences revealed several significant trends in the SRD:(1)an overall expansion of land area and intertidal vegetation,with the most pronounced changes occurring in the eastern sector;(2)the predominance of river discharge influencing the southwestern and northern sectors,contrasted with the primary impact of storm surges in the eastern sector;and(3)three distinct causal relationships among estuarine morphology,vegetation,storm surges,and river discharge:a direct model where river discharge shapes estuarine morphology,a progressive model in which river discharge affects vegetation distribution,subsequently influencing estuarine morphology,and a hybrid model where storm surges directly impact vegetation and indirectly modify its distribution through changes in estuarine morphology.The stability of sediment supply and the role of intertidal vegetation are crucial for the continuous seaward advance,providing a vital foundation for the protection and development of estuarine deltas.
基金Under the auspices of the National Natural Science Foundation of China(No.42301470,42171389)。
文摘Scientifically understanding the evolution of urbanization and analysing the coupling mechanism of human-land systems are important foundations for solving spatial conflicts and promoting regional sustainable development.This study analyzed the spatiotemporal evolution and landscape pattern change of construction land in the Yangtze River Delta(YRD)region from 1990 to 2018 by integrating Geographical Information System(GIS)spatial analysis and landscape pattern indices,and revealed its driving mechanism by XGBoost and SHapley Additive ex Planations(SHAP).Moreover,we compared the disparities in the core driving factors for construction land evolution in cities with diverse development orientations within the YRD region.Results show that:1)development intensity of construction land continued to increase from 7.54%in 1990 to 13.44%in 2018,primarily by occupying farmland.The landscape fragmentation of construction land in the YRD region decreased,and landscape dominance increased.Spatially,the eastern part of the YRD exhibits a high degree of spatial agglomeration of construction land,whereas the western part shows a high degree of fragmentation,revealing distinct spatial gradient differentiation characteristics.The landscape dominance of the construction land in the eastern region of the YRD is higher than that in the western and northern regions.2)Transportation and infrastructure exert the highest contribution rate on development intensity changes of construction land in the YRD.The industrial structure significantly influences the conversion of farmland to construction land.Additionally,infrastructure plays a crucial role in shaping the spatial agglomeration patterns of construction land.Population distribution is the dominant factor determining the regularity of the landscape shape of construction land.3)The core driving factors for the development intensity of construction land in central cities primarily lies in transportation,whereas for non-central cities,besides transportation,the year-end balance of per capita savings deposits of urban and rural residents also play a significant role.The area change of construction land occupying farmland in central and non-central cities is mainly driven by industrial structure and economic level,respectively.This study informs refined spatial optimization and regional high-quality integrated development.
基金supported by the Joint Funds of the National Natural Science Foundation of China(No.U21A2027)the New Cornerstone Science Foundation through the XPLORER PRIZE(2023-1033).
文摘This study focuses on the spatiotemporal distribution,urban-rural variations,and driving factors of ammonia Vertical Column Densities(VCDs)in China’s Yangtze River Delta region(YRD)from 2008 to 2020.Utilizing data from the Infrared Atmospheric Sounding Interfer-ometer(IASI),Generalized Additive Models(GAM),and the GEOS-Chem chemical transport model,we observed a significant increase of NH_(3)VCDs in the YRD between 2014 and 2020.The spatial distribution analysis revealed higher NH_(3)concentrations in the northern part of the YRD region,primarily due to lower precipitation,alkaline soil,and intensive agricul-tural activities.NH_(3)VCDs in the YRD region increased significantly(65.18%)from 2008 to 2020.The highest growth rate occurs in the summer,with an annual average growth rate of 7.2%during the period from 2014 to 2020.Agricultural emissions dominated NH_(3)VCDs during spring and summer,with high concentrations primarily located in the agricultural areas adjacent to densely populated urban zones.Regions within several large urban areas have been discovered to exhibit relatively stable variations in NH_(3)VCDs.The rise in NH_(3)VCDs within the YRD region was primarily driven by the reduction of acidic gases like SO_(2),as emphasized by GAM modeling and sensitivity tests using the GEOS-Chem model.The concentration changes of acidic gases contribute to over 80%of the interannual variations in NH_(3)VCDs.This emphasizes the crucial role of environmental policies targeting the reduction of these acidic gases.Effective emission control is urgent tomitigate environmental hazards and secondary particulate matter,especially in the northern YRD.
基金supported by the National Natural Science Foundation of China(No.42075177)the National Key Research and Development Program of China(No.2017YFC0210003).
文摘Extensive spatiotemporal analyses of long-trend surface ozone in the Yangtze River Delta(YRD)region and itsmeteorology-related and emission-related have not been systematically analyzed.In this study,by using 8-year-long(2015–2022)surface ozone observation data,we attempted to reveal the variation ofmultiple timescale components using the Kolmogorov–Zurbenko filter,and the effects of meteorology and emissions were quantitatively isolated using multiple linear regression with meteorological variables.The results showed that the short-term,seasonal,and long-term components accounted for daily maximum 8-hr average O_(3)(O_(3–8)hr)concentration,46.4%,45.9%,and 1.0%,respectively.The meteorological impacts account for an average of 71.8%of O_(3–8)hr,and the YRD’s eastern and northern sections aremeteorology-sensitive areas.Based on statistical analysis technology with empirical orthogonal function,the contribution of meteorology,local emission,and transport in the long-term component of O_(3–8)hr were 0.21%,0.12%,and 0.6%,respectively.The spatiotemporal analysis indicated that a distinct decreasing spatial pattern could be observed from coastal cities towards the northwest,influenced by the monsoon and synoptic conditions.The central urban agglomeration north and south of the YRD was particularly susceptible to local pollution.Among the cities studied,Shanghai,Anqing,and Xuancheng,located at similar latitudes,were significantly impacted by atmospheric transmission—the contribution of Shanghai,the maximum accounting for 3.6%.
基金funded by the 2022-2023 Australian Centre for International Agricultural Research(ACIAR)Alumni Research Support Facility(ARSF)programme:“Farmers’adaptive capacity and agricultural transformation in the Vietnamese Mekong Delta:understanding and supporting value chain engagement”the ACIAR-funded project“Farmer options for crops under saline conditions(FOCUS)in the Mekong River Delta,Vietnam”(SLaM/2018/144)to this study.
文摘Agricultural production(especially intensive rice production)is a primary income source for over 2.0×10^(7) people in the Vietnamese Mekong River Delta.However,adverse climate change impacts,socio-economic change,and high dependence on farm inputs for intensive production constrain the longer-term sustainability of rice systems.Government and agribusiness actors are encouraging more farmers to grow non-rice crops and supporting the upscaling of alternative crops to paddy rice.We used a qualitative approach to investigate the value chain characteristics,as well as constraints and opportunities of alternative crops via two case studies(baby corn and honeydew melon)in An Giang and Hau Giang provinces,Vietnam.Data collection involved focus group discussions with local farmers and interviews with farmers and industry experts.Thematic analysis was used to compile the findings,and the results were validated with local government staff.The baby corn value chain featured on-going and stable market demand(including value-addition)and better vertical coordination(e.g.,written contracts and financial support).The honeydew melon value chain featured positive relationships between farmers and traders despite less-developed vertical coordination.There are opportunities for value chain engagement through product quality certification,value-addition,and accessing high-value domestic and export markets.However,farmers require crop-specific and generic support from private and public sectors.Increased labour requirements and limited access to finance and credit limit value chain participation.Upscaling and marketing alternative crops can enhance farmer profitability and support non-farming agricultural business establishment,economic growth,and community development.Efficient value chains will be critical to ensure the adoption of alternative crops and development of crop-specific agribusiness models.These findings can inform policy-makers and change facilitators in designing targeted interventions to support the adoption of alternative crops in the study area as well as in Vietnam and globally.
基金State Key Laboratory of Lake and Watershed Science for Water Security,No.2024SKL016National Natural Science Foundation of China,No.42002204,No.42373060+1 种基金Innovative Training Program for University Students,No.2024219,No.2024224Jiangsu Provincial Government Scholarship Program for Studying Abroad,No.2024-075。
文摘Urban lakes are vital components of the modern urban water system and landscape design.They play an important role in the construction of urban ecological civilization.However,in recent years,the urban lake ecosystem has been increasingly degraded,especially with the frequent cyanobacteria blooms,which directly threatens the maintenance of ecosystem service function and sustainable urban development.In this study,several sedimentary cores were collected from Hudie Lake located in the Yangtze River Delta in China that had not been dredged for centuries.Using one of the sediment cores that spans the past 200 years,we reconstructed the long-term environmental changes and examined the driving mechanisms of both human activities and natural factors affecting the lake's dynamics.Our results indicated that,with the growth of the city,organic matter and nutrients in the lake had gradually increased.Notably,the significant increase in phosphorus had been a key factor driving cyanobacteria blooms in Hudie Lake.Since the 1960s,urban development and changes in land use around the lake had severely disturbed its natural habitats,leading to peak nutrient levels during the period from 2000 to 2010.
文摘Digital transformation,as a recent trend in socioeconomic development,is considered as a critical pathway for urban carbon reduction because of its potential to increase productivity and energy efficiency.However,few studies have explored the relationship between urban digitalization and carbon emissions(CE).Therefore,this study systematically analyzed the spatiotemporal distribution and interaction mechanism between digitalization and CE in the Yangtze River Delta(YRD)urban agglomerations of China during 2006-2020 based on a multidimensional indicator system,including digitalization industry level,digitalization application level,and urban green digitalization willingness.The findings revealed that both digitalization and CE in the YRD exhibit a significant and synchronously evolving“core-periphery”spatial pattern.Core cities generated substantial positive spillover effect on periphery cities through technology diffusion and policy demonstration,advancing both regional digitalization and the collaborative governance of CE.However,digitalization had dual impact on CE.On the one hand,it promoted the reduction of CE by enhancing energy efficiency,optimizing industrial structures,and promoting the application of green technologies.On the other hand,the expansion of digital infrastructure introduced a potential risk of increased energy consumption.Therefore,targeted policy recommendations are proposed to facilitate the coordination of environmental sustainability and digitalization in the YRD.This study provides empirical support and policy insights for advancing the coordinated development of regional digital transformation and green low-carbon initiatives.
基金supported by the National Key Research and Development Program of China(No.2019YFD1100203).
文摘Organic amine pesticides(OAPs)are widely used in modern agriculture and these compounds can contaminate drinking water sources in different ways.However,there is a lack of data on the occurrence of OAPs in drinking water and their potential human health risks.In this study,tapwater(TW)and bottledwater(BW)sampleswere collected from eight cities in the Yangtze River Delta urban agglomeration in China,and their OAP levelswere analyzed using high-throughput organic analysis testing coupled with high-volume solid-phase extraction(Hi-throat/Hi-volume SPE techniques).This study is the first to systematically characterize the trace levels of OAPs in drinking water in China.Our findings indicated that the total concentration of OAPs(OAPs)in TW(average 11.06±4.99 ng/L)was 29.4%higher than in BW(average 8.55±3.98 ng/L)and fewer kinds(7)of OAPs were detected in BW.Furthermore,the long-term intake of TW in some areas was linked to carcinogenic risks even at an acceptable OAP range,particularly in males,with molinate being the major contributor(61.3%)to OAP exposure.Further analysis revealed that the occurrence and health risks of OAPs in drinking water were mainly influenced by the quality of water sources and the technologies adopted in drinking water treatment plants(DWTPs).Furthermore,our findings demonstrated that advanced treatment technologies such as nanofiltration could more effectively remove OAPs in raw water(up to 87.5%).Therefore,our findings highlighted the importance of selecting appropriate advanced treatment technologies in DWTPs.
基金Under the auspices of the National Natural Science Foundation of China(No.42471111,42107419)the Natural Science Foundation of Shandong Province(No.ZR2023MD076)+2 种基金Talent Induction Program for Youth Innovation Teams in Colleges and Universities of Shandong Province(No.2022-2024)Youth Innovation Teams in Colleges and Universities of Shandong Province(No.2022KJ118)Jilin Provincial Department of Science and Technology Project(No.20230203174SF)。
文摘The Yellow River Delta(YRD)of China is one of the most active land-sea interaction deltas in the world.However,due to human activities and climate change,it has undergone significant changes,including the degradation of natural wetlands and saltwater intrusion.As an integral part of soil microorganisms,fungi play a crucial role in maintaining and stabilizing the function of wetland ecosystems.To better understand the composition and diversity changes of fungal communities along a salinity gradient in the YRD of China and their relationship with environmental factors,fungal diversity,abundance,and composition in the sediments of four typical vegetation communities spanning from the riverbank to the seaside were investigated.The results showed that the electrical conductivity(EC)increased significantly from the riverbank to the coastal area(P<0.05),but the levels of total nitrogen(TN),total carbon(TC),total sulfur(TS),available phosphorous(AP),and ammonium(NH_(4)^(+)-N)increased in Phragmites australis community and then experienced a significant decrease in Tamarix chinensis community and Suaeda salsa community(P<0.05).The alpha diversity(Shannon and Simpson indices)of the soil fungal community exhibited a negative correlation with EC.There was a significant alteration in the structure of the fungal community,primarily influenced by EC and NO_(3)^(-)-N.Ascomycota was found to be the most abundant phylum,and its relative abundance is positively correlated with pH and TS.The relative abundance of Sordariomycetes,the second-largest class of Ascomycota,reached 38.95%.Salinity was identified as the most important factor driving changes in soil fungal community composition.In summary,the fungal community changed significantly along the salinity gradient,and different environmental factors impacted various tiers of fungal populations differently.The findings of this study lay the groundwork for comprehending soil fungal communities and their primary influencing factors in newly formed wetlands.
基金supported by the Natural Science Foundation of Qingdao(No.23-2-1-224-zyyd-jch).
文摘The Yellow River Delta(YRD)is rich in oil,natural gas,and land resources.With the expansion of an important oil production base in North China,the increased discharge of Polycyclic aromatic hydrocarbons(PAHs)and alkylated/nitrated/oxygenated PAHs(APAHs/NPAHs/OPAHs)into the Yellow River poses a potential risk to the aquatic ecosystem and human health.A total of 42 samples were gathered from trunk streams and tributaries within the YRD region during the wet and dry seasons,and 19 PAHs,5 APAHs,16 NPAHs,and 7 OPAHswere measured.The concentrations of ƩPAHs,ƩAPAHs,ƩNPAHs and ƩOPAHs ranged between 29 and 620 ng/L,6.9–81 ng/L,0.64–9.0 ng/L,and 7.2–81 ng/L in water,respectively,and 27–420 ng/g,5.1–130 ng/g,0.19–1.8 ng/g and 3.9–51 ng/g in sediment,respectively.The oil extraction activities resulted in an increased presence of middle-high molecular weight PAHs and APAHs in sediment,and port activities had a notable influence on the proportion of 1-methylpyrene in both water and sediment.The fugacity fraction analysis suggested that sediment was a secondary source of OPAHs,while benzo[k]fluoranthene,benzo[e]pyrene,benzo[a]pyrene,and 5-methylchrysene migrated from water to sediment.The main contributors to PAHs,APAHs,NPAHs,and OPAHs in water and sediment were combustion and petroleum sources.Compared to water,sediment displayed a heightened ecological risk associated with PAHs,APAHs,NPAHs,and OPAHs.Adults residing in the YRD region were at higher risk of cancer than children,which deserves special attention.
基金supported by the National Natural Science Foundation(Nos.42275107,42121004,and 42375109)the National Key Research and Development Plan(No.2023YFC3706202)+1 种基金the Foundational and Applied Basic Research in Guangzhou in 2023(No.2023A04J0251)the Special Fund Project for Science and Technology Innovation Strategy of Guangdong Province(No.2019B121205004).
文摘The Pearl River Delta(PRD)region has been identified as a significant hotspot of wet ammonium deposition.However,the absence of long-term monitoring data in the area hinders the comprehension of the historical trends and changes in wet NH_(4)^(+)-N deposition in response to emissions,which interferes with the ability to make effective decisions.This study has analyzed the long-term trends of wet NH_(4)^(+)-N deposition flux and has quantified the effect of anthropogenic emissions and meteorological factors at a typical urban site and a typical forest site in the PRD region from 2009 to 2020.It revealed a significant decreasing trend in wet NH_(4)^(+)-N flux in both the typical urban and forest areas of the PRD region,at-6.2%/year(p<0.001)and-3.3%/year(p<0.001),respectively.Anthropogenic emissions are thought to have contributed 47%–57%of the wet NH_(4)^(+)-N deposition trend over the past 12 years compared to meteorological factors.Meteorological conditions dominated the interannual fluctuations in wet NH_(4)^(+)-N deposition with an absolute contribution of 46%–52%,while anthropogenic emissions change alone explained 10%–31%.NH_(3)emissions have the greatest impact on the urban area among anthropogenic emission factors,while SO_(2)emissions have the greatest impact on the forest area.Additionally,precipitation was identified as the primary meteorological driver for both sites.Our findings also imply that the benefits of NH_(3)emissions reductions might not immediately emerge due to interference from weather-related factors.
基金National Natural Science Foundation of China,No.42301203Strategic Public Policy Research Grant of the Policy Innovation and Coordination Office of the Hong Kong SAR Government,No.S2017.A8.007.17S+2 种基金Guangdong Basic and Applied Basic Research Foundation,No.2022A1515110969Major Program of National Social Science Foundation of China,No.21&ZD107GDAS’Project of Science and Technology Development,No.2023GDASZH-2023010101。
文摘The perfection of the cross-border regional innovation system of the Pearl River Delta(PRD)and Hong Kong region remarkably underpins the construction of the Guangdong-Hong Kong-Macao Greater Bay Area(GBA)towards an international technological innovation hub.This paper focuses on the relational characteristics of the usage of technological innovation functions and elements,including labor force,technology,and producer services from Hong Kong region by high-technology firms in the PRD,and probes into the influencing factors by integrating the objective perspective on the impact of firm-level socioeconomic attributes and subjective perspective on the open interpretations on the reasons by using or not using technological innovation functions and elements from Hong Kong region by various stakeholders in high-technology domains in the PRD.Key research findings are fourfold.First,Hong Kong's technological innovation functions primarily ride on its institutional advantages under the“One Country,Two Systems”framework to empower high-technology firms in the PRD by expanding their international market,international business operation,and financing,but cross-border investment and entrepreneurship has retrieved to a relatively marginalized position.The degree of supply-demand relations of producer services is the highest,followed by labor force and technology.Second,Hong Kong-invested,large-sized,and long-standing high-technology firms in the PRD are more inclined to use technological innovation elements from Hong Kong region,while domestic,small-and-medium-sized,and start-up high-technology firms in the PRD are in turn,gradually unhooked from the supply of technological innovation elements from Hong Kong region.Third,Hong Kong enjoys both advantages and disadvantages in supplying labor forces,technologies,and producer services to high-technology firms in the PRD,with advantages in competitiveness,international linkages and visions,and disadvantages in high cost,lack of more profound mutual understanding between Hong Kong and the PRD,and the imperfect cooperation mechanisms.Fourth,interactions among the transitioning role of Hong Kong region in the macro-level global and national economic development landscape,meso-level cross-border regional specificities under the“One Country,Two Systems”framework,and micro-level heterogeneous practices and capabilities of firms influence the usage of technological innovation functions and elements from Hong Kong region by high-technology firms in the PRD.
基金Supported by the National Natural Science Foundation of China(No.U2240220)。
文摘The river plume front between the diluted ocean water and salty ocean water in the Changjiang(Yangtze)River Delta(CRD)is well studied.Comparatively,less is known about the estuarine front in the CRD,which is formed between the riverine freshwater and the diluted ocean water and has the highest magnitude of salinity gradient(SG)in the CRD.Estuarine fronts are of great significance to the riverine material transport in the estuary.Many biogeochemical processes are enhanced in estuarine fronts,which have brought about environmental problems.In this study,the seasonal variations of the estuarine fronts in the CRD were studied in wet(July)and dry(January)seasons in 2017,based on model simulations with high spatiotemporal resolutions using the Finite-Volume Community Ocean Model(FVCOM).The estuarine front included several sharp fronts with a SG>4(/500 m),and was bottom-trapped on the submerged delta front.Seasonal changes mainly occurred off the Jiangsu coast,where a significant estuarine front was formed in July.The estuarine fronts generated around the submerged delta topography were accompanied by the offshore extension of older estuarine fronts,which were diluted and evolved into plume fronts over a tidal cycle.The simulated estuarine fronts had a salinity range of 6 to 22 in the dry season and 6 to 14 in wet season 2017.The estuarine fronts hindered the residual current by altering its flow direction to the southeast.
基金supported financially by the National Natural Science Foundation of China(Nos.42330406 and 42476163)。
文摘The historical movements of relative sea level(RSL)reflect the geomorphological dynamics around coastal regions in the past,and reconstructing the RSL curve contributes to the prediction of future RSL movements.On the basis of the sediment sequence and optical stimulated luminescence(OSL)dating data of three boreholes in the Yellow River Delta(YRD),the positions of paleo-coastlines and the movements of RSL in the last 2000 years were reconstructed.The main results are as follows:1)the YRD coast transformed from a tide-dominated silty coast to a wave-dominated sandy coast and back to a tide-dominated silty coast in the last 2000 years.2)The sand layers consisting of shell fragments indicated the locations of the coastline in 1855 AD,893 AD,and 40 BC,and their top elevations were close to the mean high water level in the corresponding years.3)The mean sea level elevation in 79 BC,1019 AD,and 1800 AD relative to the modern sea level was -4.52,-4.52,and-2.92 m,respectively.4)The RSL was almost stagnant during 79 BC-1019 AD,rose slowly during 1019-1800 AD due to the reverse change of global climate from the Little Ice Age to the Medieval Warm Period,and rose significantly after 1800 AD due to the warm period.5)The movement of RSL controlled the surface slope of YRD,which was a slope of approximately 0.022‰ at 893 AD,an inverted slope of 0.144‰ at 1855 AD,and a slope of 0.075‰ recently.These findings indicate that the modern YRD is far from being abandoned in the future,providing a historical geomorphological basis for the management of the Yellow River Estuary.
基金supported by the Anhui University Philosophy and Social Science Research Major Project[grant numbers:2023AH040033]the Anhui Housing Urban and Rural Construction Science and Technology Plan Project[grant number:2023-RK059]the Anhui Jianzhu University quality engineering project,economic management innovation team construction project[grant number:LJ22087].
文摘This study examines the degree of urban‒rural integrated development(URID)and its determinants across 41 cities within the YRDR during the period spanning from 2012 to 2021 by employing the entropy weighting method and geodetic detector model.The results reveal the following.First,the overall URID in the Yangtze River Delta region(YRDR)accelerated.Cities in the central and eastern parts exhibit a greater URID,which decreases toward the west,north,and south,highlighting prominent developmental imbalances between cities.Second,integrated economic development between urban and rural areas(URAs)has consistently demonstrated superior performance.Social integration in URA has exhibited a steady upward trajectory,whereas the integration and improvement of urban and rural residents'quality of life have advanced at a comparatively modest pace.Third,the factors that significantly influence the URID within the YRDR include per capita GDP,postal and telecommunication services per capita,and the proportion of private car ownership.Conversely,the impact of governmental intervention and agricultural security appears to be comparatively diminished.Moreover,the combined influence of interacting dual factors surpasses that of individual elements,with the influence gradually stabilizing over time.Ultimately,this study provides policy suggestions to foster integrated urban and rural development in the Yangtze River Delta(YRD)with a focus on regional collaboration and development strategies.
基金Under the auspices of National Natural Science Foundation of China(No.42371185)。
文摘Under the new development pattern,promoting the balanced development of the regional life service level is the key to attaining the goal of meeting people’s need for an improved life.This study constructed an index system with six dimensions,namely,economic base,innovation drive,living environment,transportation,public services and life security,and explored the balanced characteristics and obstacles of the life service level in the Yangtze River Delta,China in 2020 using the Gini coefficient,the standard deviation ellipse,the global spatial autocorrelation,the equilibrium entropy and the obstacle degree model.Results show that:1)the current overall level of life services in the Yangtze River Delta is in relative equilibrium,and the Gini coefficient of three dimensions,namely,economic base,innovation drive and life security,is relatively low and on the verge of imbalance.2)The spatial pattern of the six dimensions of the overall level of the life service is oriented toward the‘southeast-northwest’direction with significant spatial differentiation and spatial agglomeration.3)At present,most of the cities have a comparative advantage in the coordination of their life services,and the potential of their life service system shows room for further improvement in the future.4)Currently,the quality of economic development,talent concentration,innovation inputs,innovation outputs,basic education,health care,cultural sharing,the living standards of the urban and rural residents and the construction of a transportation system are the main factors constraining the improvement of the level of life services in the Yangtze River Delta.This study attempts to research on the evaluation and measurement of regional life service level in the new era,and provides a reference for the promotion of regional coordination and sustainable development.
基金supported by the National Key Research and Development Program of China(No.2022YFC3701204)the Natural Science Foundation of Jiangsu Province(No.BK20231300).
文摘Based on the chemical composition data of a regional long-lasting haze event that occurred in the Yangtze River Delta(YRD)region from 17 December 2023 to 8 January 2024,the evolutionary characteristics of the chemical components and sources of fine particulate matter(PM2.5)under different pollution levels were comparatively analyzed using PMF(Positive Matrix Factorization)and backward trajectory analysis.SNA(NO_(3)^(-),NH_(4)^(+),SO_(4)^(2-))was found to be the primary chemical component of PM2.5,making up 63.6%(clean days)to 69.7%(heavy pollution)of it.The NO_(3)^(-)concentration was 3.14(clean days)to 6.01(heavy pollution)times higher than that of SO_(4)^(2-).NO_(3)^(-),POC,Fe,Mn,Al concentrations increased,while SOC,EC,crustal elements(Ca,Si)and other water-soluble ions(WSIs)concentrations decreased as the pollution level increased.The contribution of secondary inorganics and biomass-burning emissions and industrial and ship emissions increased significantly as the pollution level increased,which accounted for 40.3%and 36.7%,respectively,in the heavy pollution stage.The contribution of traffic sources decreases gradually with increasing pollution levels,accounting for only 59.1%of the light pollution stage in the heavy pollution stage.PM_(2.5) and its main chemical components showed similar potential source distribution,located in the northwest(Fuyang,Huainan,Nanjing),south(Taizhou,Lishui,Jiande)and north(Taizhou,Yancheng).However,distinct transport routes were observed under the different air quality levels.During the heavy pollution period,the polluted air masses primarily came from the harbor regions,whereas during the light pollution period they were transported from the southeast(Taizhou)and the North China Plain.
基金Under the auspices of the National Natural Science Foundation of China(No.42471380,42325104,42101350)。
文摘Accurate mapping of wetlands is crucial for wetlands conservation, as well as for monitoring and assessing coastal resources and the environment. Multispectral(MSI) satellite image time series have rich temporal evolution characteristics, which can reveal dynamic changes in surface cover and environmental conditions. However, due to the limited number of bands, the ability to express the difference of ground features is limited, resulting in an inability to capture surface objects' changes in the finer spectral range. Therefore,this paper proposed a dual-branch spatial-temporal spectral feature fusion network(Fusion-Former), which combined MSI time series data with hyperspectral(HSI) data to achieve accurate mapping of wetlands in Liaohe River Delta, China in 2022. Fusion-Former achieved an overall accuracy(OA) of 96.36% in the Liaohe River Delta wetland, significantly outperforming all benchmark methods.Experimental results demonstrate that utilizing the temporal phenological information from multi-temporal MSI and the fine-grained spatial-spectral features from HSI can effectively resolve the misclassification between spectrally similar vegetation and water bodies.Furthermore, a continuous improvement in accuracy was observed as the length of the input time series increased, underscoring the critical role of temporal information. Therefore, by integrating these complementary information sources, the proposed method enables the generation of accurate wetland maps to support decision-makers in formulating more precise conservation and management strategies.
