The sinking of diatoms is critic al to the formation of oceanic biological pumps and coastal hypoxic zones.However,little is known about the effects of different nutrient restrictions on diatom sinking.In this study,w...The sinking of diatoms is critic al to the formation of oceanic biological pumps and coastal hypoxic zones.However,little is known about the effects of different nutrient restrictions on diatom sinking.In this study,we measured the sinking velocity(SV) of Thalassiosira weissflogii using a new phytoplankton video observation instrument and analyzed major biochemical components under varying nutrient conditions.Our results showed that the SV of T.weissflogii under different nutrient limitation conditions varied substantially.The highest SV of(1.77±0.02) m/d was obtained under nitrate limitation,signific antly surpassing that under phosphate limitation at(0.98±0.13) m/d.As the nutrient limitation was released,the SV steadily decreased to(0.32±0.03) m/d and(0.15±0.05) m/d,respectively.Notably;under conditions with limited nitrate and phosphate concentrations,the SV values of T.weissflogii significantly positively correlated with the lipid content(P <0.001),with R^(2) values of 0.86 and 0.69,respectively.The change of the phytoplankton SV was primarily related to the intracellular compo sition,which is controlled by nutrient conditions but did not significantly correlate with transparent extracellular polymer and biosilica contents.The results of this study help to understand the regulation of the vertical sinking process of diatoms by nutrient restriction and provide new insights into phytoplankton dynamics and their relationship with the marine nutrient structure.展开更多
Combined with the advanced drilling of the central return air shaft in Kekegai Coal Mine,the distribution law of slag discharge flow field by drilling method and the influencing factors of slag discharge effect are st...Combined with the advanced drilling of the central return air shaft in Kekegai Coal Mine,the distribution law of slag discharge flow field by drilling method and the influencing factors of slag discharge effect are studied.Firstly,the numerical model of gas–liquid–solid coupling slag discharge is established by CFD-DEM(computational fluid dynamics coupled discrete element method).Then,the flow field distribution law of the site slag outlet layout model and the optimization model is compared and analyzed.Finally,the influence of drilling parameters on slag discharge effect is studied.The results show that the best arrangement of slag suction ports is:the number is two,the length-diameter ratio is 0.4,the area ratio is 1,and the total area ratio is 1.94%.The fluid movement at the bottom of the well is mainly tangential flow,while the fluid in the slag discharge pipe is mainly axial flow.The construction parameters of efficient slag discharge are put forward:bit rotation speed is 8.7 r/min,gas injection rate is 4200 m^(3)/h,air duct sinking ratio is 0.84,and mud viscosity is 165 MPa·s.The research results can provide useful theoretical reference for large-scale sinking construction in deep wells.展开更多
The sinking of phytoplankton is critical to organic matter transportation in the ocean and it is an essential process for the formation of coastal hypoxic zones.This study was based on a field investigation conducted ...The sinking of phytoplankton is critical to organic matter transportation in the ocean and it is an essential process for the formation of coastal hypoxic zones.This study was based on a field investigation conducted during the summer of 2022 in the Changjiang River(Yangtze River) Estuary(CJE) and its adjacent waters.The settling column method was employed to measure the sinking velocity(SV) of different size fractions of phytoplankton at the surface of the sea and to analyze their environmental control mechanisms.The findings reveal significant spatial variation in phytoplankton SV(-0.55-2.41 m/d) within the CJE.High-speed sinking was predominantly observed in phosphate-depleted regions beyond the CJE front.At the same time,an upward trend was more commonly observed in the phosphate-rich regions near the CJE mouth.The SV ranges for different sizefractionated phytoplankton,including micro-(>20 μm),nano-(2-20 μm),and picophytoplankton(0.7-2 μm),were-0.50-4.74 m/d,-1.04-1.59 m/d,and-1.24-1.65 m/d,respectively.Correlation analysis revealed a significant negative correlation between SV and dissolved inorganic phosphorus(DIP),implying that the influence of DIP contributes to SV.The variations in phytoplankton alkaline phosphatase activity suggested a significant increase in SV across all size fractions in the event of phosphorus limitation.Phytoplankton communities with limited photo synthetic capacity(maximum photochemical efficience,Fv/Fm <0.3) were found to have higher SV than that of communities with strong capacity,suggesting a link between sinking and alterations in physiological conditions due to phosphate depletion.The findings from the in situ phosphate enrichment experiments confirmed a marked decrease in SV following phosphate supplementation.These findings suggest that phosphorus limitation is the primary driver of elevated SV in the CJE.This study enhances the comprehension of the potential mechanisms underlying hypoxic zone formation in the CJE,providing novel insights into how nearshore eutrophication influences organic carbon migration.展开更多
Modern aircraft tend to use fuel thermal management systems to cool onboard heat sources.However,the design of heat transfer architectures for fuel thermal management systems relies on the experience of the engineers ...Modern aircraft tend to use fuel thermal management systems to cool onboard heat sources.However,the design of heat transfer architectures for fuel thermal management systems relies on the experience of the engineers and lacks theoretical guidance.This paper proposes a concise graph representation method based on graph theory for fuel thermal management systems,which can represent all possible connections between subsystems.A generalized optimization algorithm is proposed for fuel thermal management system architecture to minimize the heat sink.This algorithm can autonomously arrange subsystems with heat production differences and efficiently utilize the architecture of the fuel heat sink.At the same time,two evaluation indices are proposed from the perspective of subsystems.These indices intuitively and clearly show that the reason for the high efficiency of heat sink utilization is the balanced and moderate cooling of each subsystem and verify the rationality of the architecture optimization method.A set of simulations are also conducted,which demonstrate that the fuel tank temperature has no effect on the performance of the architecture.This paper provides a reference for the architectural design of aircraft fuel thermal management systems.The metrics used in this paper can also be utilized to evaluate the existing architecture.展开更多
This study focuses on urgent research on restoring and enhancing carbon storage capacity in the Beibu Gulf Urban Agglomer-ation of China,a key area in the‘Belt and Road’Initiative,which aligns with carbon peaking an...This study focuses on urgent research on restoring and enhancing carbon storage capacity in the Beibu Gulf Urban Agglomer-ation of China,a key area in the‘Belt and Road’Initiative,which aligns with carbon peaking and neutrality goals.This research ana-lyzes the spatial characteristics of carbon metabolism from 2000 to 2020 and uses models to identify stable carbon sink areas,positive carbon flow corridors,and carbon sequestration nodes.The goal is to construct a carbon metabolism spatial security pattern(CMSSP)and propose territorial ecological restoration strategies under different development demand scenarios.The results show the following:1)in 2020,the study area’s carbon sink decreased by 8.29×10^(4) t C/yr compared with that in 2010 and by 10.83×10^(4) t C/yr compared with that in 2000.High-carbon sinks were found mainly in mountainous areas,whereas low-carbon sinks are concentrated in urban con-struction land,rural residential areas,and land margins.2)From 2000 to 2020,the spatial security pattern of carbon metabolism tended to be‘high in the middle of the east and west and low in the gulf.’In 2000,2010,and 2020,16 stable carbon sinks were identified.The carbon energy flow density in Guangxi was greater than that in Guangdong and Hainan,with positive carbon flow corridors located primarily in Guangxi and Guangdong.The number of carbon sequestration nodes remained stable at approximately 15,mainly in Guangxi and Hainan.3)Scenario simulations revealed that under the Nature-based mild restoration scenario,the carbon sink rate will reach 611.85×10^(4) t C/yr by 2030 and increase to 612.45×10^(4) t C/yr by 2060,with stable carbon sinks increasing to 18.In the restora-tion scenario based on Anti-globalization,the carbon sink will decrease from 610.24×10^(4) t C/yr in 2030 to 605.19×10^(4) t C/yr in 2060,with the disappearance of some positive carbon flow corridors and stable carbon sinks.Under the Human-based sustainable restoration scenario,the carbon sink area will decrease from 607.00×10^(4) t C/yr in 2030 to 596.39×10^(4) t C/yr in 2060,with carbon sink areas frag-menting and positive carbon flow corridors becoming less dense.4)On the basis of the current and predicted CMSSPs,this study ex-plores spatial ecological restoration strategies for high-carbon storage areas in bay urban agglomerations at four levels:the land control region,urban agglomeration structure system,carbon sink structure and bay structure control region.展开更多
The arsenic(As)release from sediments in great lakes is affected by various factors.In this study,the characteristics of As release fromsediments was investigated,and the As sources and sinks with the strengths in sed...The arsenic(As)release from sediments in great lakes is affected by various factors.In this study,the characteristics of As release fromsediments was investigated,and the As sources and sinks with the strengths in sediments from different areas(grass-type,algae-type,and grass-algae alternation areas)in great shallow lakes(Taihu Lake,China)were analyzed,and the influence of P competition in the process of As release was also studied.The results showed that changing trend of the values of equilibrium As concentration in sediments were consistent with the regional changes(0 to 28.12μg/L),and the sediments from algaetype areas had the higher values.The sediments from western lake and northwest lake bay were a strong As and a weak P source,and the north lake bay had the opposite trend of these two regions.Intense P source competition with As from the sediments occurred in algae-type areas.The grass-type areas had strong As and P retention capacities,indicating a sink role of sediment with high As and P sorption capacities.The degree of As and P saturation had similar trend in sediments,and the grass-type areas had the higher values,18.3%-21.4%and 15.31%-20.34%,respectively.Contribution analysis results showed that most of As release contribution was from the bottom(30-50 cm)sediments,and the surface(0-10 cm)sediments from algae-type areas contributed more to the overlying water than other region.展开更多
[Objectives]To assess the carbon sink capacity in seawater suspension cage aquaculture of shellfish in Tianjin from 2015 to 2022.[Methods]The carbon sink capacity of different shellfish species was evaluated using bot...[Objectives]To assess the carbon sink capacity in seawater suspension cage aquaculture of shellfish in Tianjin from 2015 to 2022.[Methods]The carbon sink capacity of different shellfish species was evaluated using both physical and value assessment methods.[Results]The shellfish cultivated in seawater suspension cages in Tianjin exhibited a significant capacity for carbon sinks.The amounts of carbon removed by suspension cage aquaculture of Rapana venosa,Crassostrea gigas,Scapharca subcrenata,Scapharca broughtonii and Argopectens irradias were 448.297,403.398,89.463,40.657,and 106.719 t,respectively.Furthermore,the total volume of shellfish cultivated in seawater exhibited a consistent upward trend over time,correlating with an annual increase in the amount of carbon removed.Among the shellfish cultivated in seawater suspension cages,the order of carbon sink capacity was as follows:C.gigas>R.venosa>A.irradias>S.subcrenata and S.broughtonii.In terms of the carbon sink capacity of soft tissues,the ranking was as follows:A.irradias>R.venosa>C.gigas>S.subcrenata and S.broughtonii.The structural and yield factors associated with seawater suspension cage aquaculture of shellfish significantly influenced the enhancement of the total carbon sink of cultivated shellfish.Notably,structural factors had a greater impact on the increase in the carbon sink of cultivated shellfish compared to total yield factors.[Conclusions]The findings will serve as a reference for enhancing the carbon sink potential of fisheries and achieving sustainable development in seawater aquaculture in Tianjin.展开更多
The experimental analysis takes too much time-consuming process and requires considerable effort,while,the Artificial Neural Network(ANN)algorithms are simple,affordable,and fast,and they allow us to make a relevant a...The experimental analysis takes too much time-consuming process and requires considerable effort,while,the Artificial Neural Network(ANN)algorithms are simple,affordable,and fast,and they allow us to make a relevant analysis in establishing an appropriate relationship between the input and output parameters.This paper deals with the use of back-propagation ANN algorithms for the experimental data of heat transfer coefficient,Nusselt number,and friction factor of water-based Fe_(3)O_(4)-TiO_(2) magnetic hybrid nanofluids in a mini heat sink under magnetic fields.The data considered for the ANN network is at different Reynolds numbers(239 to 1874),different volume concentrations(0%to 2.0%),and different magnetic fields(250 to 1000 G),respectively.Three types of ANN back-propagation algorithms Levenberg-Marquardt(LM),Broyden-Fletcher-Goldfarb-Shanno Quasi Newton(BFGS),and Variable Learning Rate Gradient Descent(VLGD)were used to train the heat transfer coefficient,Nusselt number,and friction factor data,respectively.The ANOVA t-test analysis was also performed to determine the relative accuracy of the three ANN algorithms.The Nusselt number of 2.0%vol.of Fe_(3)O_(4)-TiO_(2) hybrid nanofluid is enhanced by 38.16%without a magnetic field,and it is further enhanced by 88.93%with the magnetic field of 1000 Gauss at a Reynolds number of 1874,with respect to the base fluid.A total of 126 datasets of heat transfer coefficient,Nusselt number,and friction factor were used as input and output data.The three ANN algorithms of LM,BFGS,and VLGD,have shown good acceptance with the experimental data with root-mean-square errors of 0.34883,0.25341,and 1.0202 with correlation coefficients(R2)of 0.99954,0.9967,and 0.94501,respectively,for the Nusselt number data.Moreover,the three ANN algorithms predict root-mean-square errors of 0.001488,0.005041,and 0.006924 with correlation coefficients(R2)of 0.99982,0.99976,and 0.99486,respectively,for the friction factor data.Compared to BFGS and VLGD algorithms,the LM algorithm predicts high accuracy for Nusselt number,and friction factor data.The proposed Nusselt number and friction factor correlations are also discussed.展开更多
The accelerated pace of natural and human-driven climate change presents profound challenges for Earth's systems.Oceans and ice sheets are critical regulators of climate systems,functioning as carbon sinks and the...The accelerated pace of natural and human-driven climate change presents profound challenges for Earth's systems.Oceans and ice sheets are critical regulators of climate systems,functioning as carbon sinks and thermal reservoirs.However,they are increasingly vulnerable to warming and greenhouse gas emissions.展开更多
Data center cooling systems are substantial energy consumers,and managing the heat generated by electronic devices is becoming more complex as chip power levels continue to rise.The single-phase immersion cooling(SPIC...Data center cooling systems are substantial energy consumers,and managing the heat generated by electronic devices is becoming more complex as chip power levels continue to rise.The single-phase immersion cooling(SPIC)server with oil coolant is numerically investigated using the validated Re-Normalization Group(RNG)k-εmodel.For the investigated scenarios where coolant velocity at the tank inlet is 0.004 m/s and the total power is 740 W,the heat transfer between the heat sinks and the coolant is dominated by natural convection,although forced convection mediates the overall heat transfer inside the tank.The maximum velocity of coolant through the heat sink is 0.035 m/s and the average heat transfer coefficient is up to 75.8 W/(m2·K).The geometry of the heat sink is important for the cooling performance.Increasing both the fin thickness and number enhances the natural convection effect of the heat sink,but also increases the flow resistance.The heat sink with a fin thickness of 3 mm performs the best,reducing the average graphics processing unit(GPU)temperature from 71.3℃ to 68.6℃.A heat sink with an optimal fin number of 16 reduces the average GPU temperature to 67.7℃.As for the effect of fin height,increasing it from 15 to 30 mm results in increases in the heat transfer area and flow rate by about 72%and 32%,respectively,which reduces the average GPU temperature to 65.2℃.Therefore,the importance of fin parameters ranks in the following order:fin height,number,and thickness.This study highlights the potential application of oil coolants in SPIC systems and offers theoretical guidance for the efficient design of natural convection cooling solutions.展开更多
Climate change is the most severe ecological challenge faced by the world today.Forests,the dominant component of terrestrial ecosystems,play a critical role in mitigating climate change due to their powerful carbon s...Climate change is the most severe ecological challenge faced by the world today.Forests,the dominant component of terrestrial ecosystems,play a critical role in mitigating climate change due to their powerful carbon sequestration capabilities.Meanwhile,climate change has also become a major factor affecting the sustainable management of forest ecosystems.Climate-Smart Forestry(CSF)is an emerging concept in sustainable forest management.By utilizing advanced technologies,such as information technology and artificial intelligence,CSF aims to develop innovative and proactive forest management methods and decision-making systems to address the challenges of climate change.CSF aims to enhance forest ecosystem resilience(i.e.,maintain a condition where,even when the state of the ecosystem changes,the ecosystem functions do not deteriorate)through climate change adaptation,improve the mitigation capabilities of forest ecosystems to climate change,maintain high,stable,and sustainable forest productivity and ecosystem services,and ultimately achieve harmonious development between humans and nature.This concept paper:(1)discusses the emergence and development of CSF,which integrates Ecological Forestry,Carbon Forestry,and Smart Forestry,and proposes the concept of CSF;(2)analyzes the goals of CSF in improving forest ecosystem stability,enhancing forest ecosystem carbon sequestration capacity,and advocating the application and development of new technologies in CSF,including artificial intelligence,robotics,Light Detection and Ranging,and forest digital twin;(3)presents the latest practices of CSF based on prior research on forest structure and function using new generation information technologies at Qingyuan Forest,China.From these practices and reflections,we suggested the development direction of CSF,including the key research topics and technological advancement.展开更多
Kinetics of the gas-phase reactions of•OH radicals with a series of fluoroesters were studied for the first time at 298±3 K and atmospheric pressure.Relative rate coefficients were determined by in situ FTIR spec...Kinetics of the gas-phase reactions of•OH radicals with a series of fluoroesters were studied for the first time at 298±3 K and atmospheric pressure.Relative rate coefficients were determined by in situ FTIR spectroscopy in nitrogen and GC-FID in air to monitor the decay of reactants and references.The following coefficient values(in 10^(−12)cm^(3)/(molecule•sec))were obtained for ethyl fluoroacetate(EFA),ethyl 4,4,4-trifluorobutyrate(ETB),and butyl fluoroacetate(BFA),respectively:k_(1)(EFA+OH)=1.15±0.25 by FTIR and 1.34±0.23 by GC-FID;k_(2)(ETB+OH)=1.61±0.36 by FTIR and 2.02±0.30 by GC-FID;k_(3)(BFA+OH)=2.24±0.37 by FTIR.Reactivity trends were developed and correlated with the number of CH_(3)and F substituents in the fluoroester,and structure-activity relationships(SARs)calculations were performed.In addition,the tropospheric lifetimes of EFA,ETB,and BFA upon degradation by OH radicals were calculated to be 9,6,and 5 days,respectively,indicating that these fluorinated compounds could have a possible regional effect from the emission source.Relatively small photochemical ozone creation potentials of 9,7,and 19 were estimated for EFA,ETB,and BFA,respectively.The GlobalWarming Potentials(GWPs)for EFA,ETB,and BFA were calculated for different time horizons.For a 20-year time horizon,the GWPs were 1.393,0.063,and 0.062,respectively.In the case of a 100-year time horizon,the GWPs were 0.379,0.017,and 0.017,and for a 500-year time horizon,the GWPs were 0.108,0.005,and 0.005 for EFA,ETB,and BFA.展开更多
Suppressing micro-amplitude vibrations is a critical issue in aerospace engineering.While nonlinear energy sinks(NES)are effective for passive vibration damping,their performance diminishes for micro-amplitude vibrati...Suppressing micro-amplitude vibrations is a critical issue in aerospace engineering.While nonlinear energy sinks(NES)are effective for passive vibration damping,their performance diminishes for micro-amplitude vibrations.This paper introduces a motion-amplified NES(MANES)to address this challenge.The system’s governing equations are derived using Hamilton’s principle,and an approximate analytical solution is validated by numerical methods.The effects of various parameters are explored,with higher vibration reduction efficiency achievable through parameter adjustments.Compared to cubic NES,MANES shows superior vibration suppression and a broader reduction bandwidth for micro-amplitude excitations.Additionally,MANES enters the effective vibration reduction range at lower excitation levels,indicating a reduced threshold for vibration suppression.This study provides insight into the vibration suppression mechanism of MANES,offering a theoretical foundation for mitigating micro-amplitude vibrations in engineering applications.展开更多
Forests play a critical role in mitigating cli-mate change by sequestering carbon,yet their responses to environmental shifts remain complex and multifaceted.This special issue,“Tree Rings,Forest Carbon Sink,and Clim...Forests play a critical role in mitigating cli-mate change by sequestering carbon,yet their responses to environmental shifts remain complex and multifaceted.This special issue,“Tree Rings,Forest Carbon Sink,and Climate Change,”compiles 41 interdisciplinary studies exploring forest-climate interactions through dendrochro-nological and ecological approaches.It addresses climate reconstruction(e.g.,temperature,precipitation,isotopes)using tree-ring proxies,species-specific and age-dependent growth responses to warming and drought,anatomical adap-tations,and methodological innovations in isotope analysis and multi-proxy integration.Key findings reveal ENSO/AMO modulation of historical climates,elevation-and latitude-driven variability in tree resilience,contrasting carbon dynamics under stress,and projected habitat shifts for vulnerable species.The issue underscores forests’dual role as climate archives and carbon regulators,offering insights for adaptive management and nature-based climate solutions.Contributions bridge micro-scale physiological processes to macro-scale ecological modeling,advancing sustainable strategies amid global environmental challenges.展开更多
The exchange of inorganic nutrients at the coastal sediment-water interface(SWI)plays a crucial role in regulating the nutrient budget in overlying water.The related studies mainly focus on the mid-to high-latitude re...The exchange of inorganic nutrients at the coastal sediment-water interface(SWI)plays a crucial role in regulating the nutrient budget in overlying water.The related studies mainly focus on the mid-to high-latitude regions,leaving a significant gap in the quantitative assessment of nutrient exchange and environmental controls at the SWI in lowlatitude coastal regions.We quantitatively assess the exchange of inorganic nutrients at the SWI in three tropical bays(Dongzhai Harbor,Xiaohai Lagoon,Qinglan Harbor).Sediments act as a source of ammonium,phosphate,and silicate,but for nitrate,sediments can be both a source and sink,although with substantial spatial and temporal variations in their fluxes.Labile organic matter is a critical regulator for the fluxes of inorganic nutrients at the SWI.The sedimentary nutrients input with high N/P molar ratio will alter the nutrient stoichiometry to mitigate the nitrogen limitation in coastal waters.However,the internal sediment release in these tropical bays plays a relative weak role in contributing to the nutrient addition in comparison with the other external nutrient sources including riverine input,submarine groundwater discharge,and atmospheric deposition.According to the global compilation on SWI nutrient fluxes,we propose that water column primary production and external inputs to interpret the variation in exchange and fluxes of nutrients at the SWI in different ecosystems.Such a conceptual understanding of these chain biogeochemical processes involving external nutrient input,primary production,particulate organic matter settling,and the accumulation and release of inorganic nutrients in sediments will be helpful for the scientific-based pollution prevent and control in coastal waters.展开更多
China is the world's largest carbon dioxide(CO_(2)) emitter and a major trading country. Both anthropogenic and natural factors play a critical role in its carbon budget. However,previous studies mostly focus on e...China is the world's largest carbon dioxide(CO_(2)) emitter and a major trading country. Both anthropogenic and natural factors play a critical role in its carbon budget. However,previous studies mostly focus on evaluating anthropogenic emissions or the natural carbon cycle separately, and few included trade-related(import and export) CO_(2) emissions and its contribution on global warming. Using the Carbon Tracker CT2019 assimilation dataset and China trade emissions from the Global Carbon Project, we found that the change trend of global CO_(2) flux had obvious spatial heterogeneity, which is mainly affected by anthropogenic CO_(2) flux. From 2000 to 2018, carbon emissions from fossil fuels in the world and in China all showed an obvious increasing trend, but the magnitude of the increase tended to slow down.In 2018, the radiative forcing(RF) caused by China's import and export trade was-0.0038 W m^(-2), and the RF caused by natural carbon budget was-0.0027 W m^(-2), offsetting 1.54% and 1.13% of the RF caused by fossil fuels that year, respectively. From 2000 to 2018, the contribution of China's carbon emission from fossil fuels to global RF was 11.32%. Considering China's import and export trade, the contribution of anthropogenic CO_(2) emission to global RF decreased to 9.50%. Furthermore, taking into account the offset of carbon sink from China's terrestrial ecosystems, the net contribution of China to global RF decreased to 7.63%. This study demonstrates that China's terrestrial ecosystem and import and export trade are all mitigating China's impact on global anthropogenic warming, and also confirms that during the research process on climate change, comprehensively considering the carbon budget from anthropogenic and natural carbon budgets is necessary to systematically understand the impacts of regional or national carbon budgets on global warming.展开更多
As a vital component of the national economic system,the forestry economy plays a significant role in promoting economic and social development.With the increasing emphasis on green and sustainable development,the car...As a vital component of the national economic system,the forestry economy plays a significant role in promoting economic and social development.With the increasing emphasis on green and sustainable development,the carbon sink market has gained widespread attention and experienced rapid expansion,exerting a profound impact on the sustainable development of the forestry economy.In this new stage,deepening the relationship between the carbon sink market and the forestry economy is of great practical significance for enhancing forest coverage,advancing forestry economic growth,and fostering green ecological development.This paper analyzes the impact of the carbon sink market on the sustainable development of the forestry economy and explores specific strategies for its advancement.展开更多
China is the largest emitter of anthropogenic CO_(2) globally,with its cities recognized as significant emission hotspots.Consequently,evaluating anthropogenic CO_(2) emissions and the carbon neutral capability(CNC)of...China is the largest emitter of anthropogenic CO_(2) globally,with its cities recognized as significant emission hotspots.Consequently,evaluating anthropogenic CO_(2) emissions and the carbon neutral capability(CNC)of Chinese cities is critical for climate change mitigation.Despite this importance,no studies to date have assessed recent and future city-scale CNCs using the top-down atmospheric inversion approach,revealing substantial knowledge gaps regarding regional CO_(2) budgets.To address these issues,this research focused on Hangzhou,a megacity known for having the highest forest cover among China’s provincial capitals,as study region.Year-round atmospheric CO_(2) concentration measurements were conducted from December 2020 to November 2021 at two sites:one urban and one suburban.These observations,along with their difference,were utilized to derive city-scale posterior anthropogenic CO_(2) emissions and to evaluate recent and future CNCs.Our key findings are as follows:(1)The manufacturing industry,energy industry and oil refineries/transformation industry were identified as the largest contributors to urban-suburban CO_(2) difference,accounting for 36.5%,21.3%,and 16.6%,respectively.Additionally,82.5%,65.2%,81.2%and 86.3%of total anthropogenic CO_(2) enhancements were attributed to emissions within Hangzhou city in winter,spring,summer and autumn,respectively.(2)The posterior annual anthropogenic CO_(2) emission for Hangzhouwas estimated at 4.65(±0.72)×10^(10) kg/a,indicating significant biases among different prior CO_(2) emission inventories.The annual biological CO_(2) sink,derived from multiple products,was estimated at-0.48(±0.16)×10^(10) kg.(3)The calculated CNC for 2021was 10.3%±3.4%,highlighting a substantial gap towards achieving full carbon neutrality.Considering potential increases in ecosystem carbon sinks due to forest age and uncertainties from climate change,it was predicted that at least 65.2%-82.6%of anthropogenic CO_(2) emissions must be reduced to achieve the goal of full carbon neutrality by year of 2060.展开更多
基金The Key R&D Program of Zhejiang under contract No.2023C03120the Science Foundation of Donghai Laboratory under contract No.DH-2022KF0215+2 种基金the National Key Research and Development Program of China under contract No.2021YFC3101702the National Programme on Global Change and Air-Sea Interaction (PhaseⅡ)—Hypoxia and Acidification Monitoring Warning Project in the Changjiang EstuaryLong-term Observation and Research Plan in the Changjiang Estuary and Adjacent East China Sea (LORCE) Project under contract No.SZ2001。
文摘The sinking of diatoms is critic al to the formation of oceanic biological pumps and coastal hypoxic zones.However,little is known about the effects of different nutrient restrictions on diatom sinking.In this study,we measured the sinking velocity(SV) of Thalassiosira weissflogii using a new phytoplankton video observation instrument and analyzed major biochemical components under varying nutrient conditions.Our results showed that the SV of T.weissflogii under different nutrient limitation conditions varied substantially.The highest SV of(1.77±0.02) m/d was obtained under nitrate limitation,signific antly surpassing that under phosphate limitation at(0.98±0.13) m/d.As the nutrient limitation was released,the SV steadily decreased to(0.32±0.03) m/d and(0.15±0.05) m/d,respectively.Notably;under conditions with limited nitrate and phosphate concentrations,the SV values of T.weissflogii significantly positively correlated with the lipid content(P <0.001),with R^(2) values of 0.86 and 0.69,respectively.The change of the phytoplankton SV was primarily related to the intracellular compo sition,which is controlled by nutrient conditions but did not significantly correlate with transparent extracellular polymer and biosilica contents.The results of this study help to understand the regulation of the vertical sinking process of diatoms by nutrient restriction and provide new insights into phytoplankton dynamics and their relationship with the marine nutrient structure.
基金supported by the National Natural Science Foundation of China(52174104 and 51674006)Key R&D projects in Anhui Province(202004a07020034)the Graduate Innovation Fund of Anhui University of Science and Technology(2023cx2053and2023cx1006)。
文摘Combined with the advanced drilling of the central return air shaft in Kekegai Coal Mine,the distribution law of slag discharge flow field by drilling method and the influencing factors of slag discharge effect are studied.Firstly,the numerical model of gas–liquid–solid coupling slag discharge is established by CFD-DEM(computational fluid dynamics coupled discrete element method).Then,the flow field distribution law of the site slag outlet layout model and the optimization model is compared and analyzed.Finally,the influence of drilling parameters on slag discharge effect is studied.The results show that the best arrangement of slag suction ports is:the number is two,the length-diameter ratio is 0.4,the area ratio is 1,and the total area ratio is 1.94%.The fluid movement at the bottom of the well is mainly tangential flow,while the fluid in the slag discharge pipe is mainly axial flow.The construction parameters of efficient slag discharge are put forward:bit rotation speed is 8.7 r/min,gas injection rate is 4200 m^(3)/h,air duct sinking ratio is 0.84,and mud viscosity is 165 MPa·s.The research results can provide useful theoretical reference for large-scale sinking construction in deep wells.
基金The National Programme on Global Change and Air-Sea Interaction (PhaseⅡ)—Hypoxia and Acidification Monitoring and Warning Project in the CE under contract No.GASI-01-CJKthe Science Foundation of Donghai Laboratory under contract No.DH-2022KF0215+3 种基金the Oceanic Interdisciplinary Program of Shanghai Jiao Tong UniversityScientific Research Fund of the Second Institute of Oceanography,MNR under contract No.SL2022ZD207the National Key R&D Program of China under contract No.2021YFC3101702the Long-term Observation and Research Plan in the Changjiang Estuary and Adjacent East China Sea (LORCE)Project under contract No.SZ2001。
文摘The sinking of phytoplankton is critical to organic matter transportation in the ocean and it is an essential process for the formation of coastal hypoxic zones.This study was based on a field investigation conducted during the summer of 2022 in the Changjiang River(Yangtze River) Estuary(CJE) and its adjacent waters.The settling column method was employed to measure the sinking velocity(SV) of different size fractions of phytoplankton at the surface of the sea and to analyze their environmental control mechanisms.The findings reveal significant spatial variation in phytoplankton SV(-0.55-2.41 m/d) within the CJE.High-speed sinking was predominantly observed in phosphate-depleted regions beyond the CJE front.At the same time,an upward trend was more commonly observed in the phosphate-rich regions near the CJE mouth.The SV ranges for different sizefractionated phytoplankton,including micro-(>20 μm),nano-(2-20 μm),and picophytoplankton(0.7-2 μm),were-0.50-4.74 m/d,-1.04-1.59 m/d,and-1.24-1.65 m/d,respectively.Correlation analysis revealed a significant negative correlation between SV and dissolved inorganic phosphorus(DIP),implying that the influence of DIP contributes to SV.The variations in phytoplankton alkaline phosphatase activity suggested a significant increase in SV across all size fractions in the event of phosphorus limitation.Phytoplankton communities with limited photo synthetic capacity(maximum photochemical efficience,Fv/Fm <0.3) were found to have higher SV than that of communities with strong capacity,suggesting a link between sinking and alterations in physiological conditions due to phosphate depletion.The findings from the in situ phosphate enrichment experiments confirmed a marked decrease in SV following phosphate supplementation.These findings suggest that phosphorus limitation is the primary driver of elevated SV in the CJE.This study enhances the comprehension of the potential mechanisms underlying hypoxic zone formation in the CJE,providing novel insights into how nearshore eutrophication influences organic carbon migration.
文摘Modern aircraft tend to use fuel thermal management systems to cool onboard heat sources.However,the design of heat transfer architectures for fuel thermal management systems relies on the experience of the engineers and lacks theoretical guidance.This paper proposes a concise graph representation method based on graph theory for fuel thermal management systems,which can represent all possible connections between subsystems.A generalized optimization algorithm is proposed for fuel thermal management system architecture to minimize the heat sink.This algorithm can autonomously arrange subsystems with heat production differences and efficiently utilize the architecture of the fuel heat sink.At the same time,two evaluation indices are proposed from the perspective of subsystems.These indices intuitively and clearly show that the reason for the high efficiency of heat sink utilization is the balanced and moderate cooling of each subsystem and verify the rationality of the architecture optimization method.A set of simulations are also conducted,which demonstrate that the fuel tank temperature has no effect on the performance of the architecture.This paper provides a reference for the architectural design of aircraft fuel thermal management systems.The metrics used in this paper can also be utilized to evaluate the existing architecture.
基金Under the auspices of the National Natural Science Foundation of China(No.52268008)。
文摘This study focuses on urgent research on restoring and enhancing carbon storage capacity in the Beibu Gulf Urban Agglomer-ation of China,a key area in the‘Belt and Road’Initiative,which aligns with carbon peaking and neutrality goals.This research ana-lyzes the spatial characteristics of carbon metabolism from 2000 to 2020 and uses models to identify stable carbon sink areas,positive carbon flow corridors,and carbon sequestration nodes.The goal is to construct a carbon metabolism spatial security pattern(CMSSP)and propose territorial ecological restoration strategies under different development demand scenarios.The results show the following:1)in 2020,the study area’s carbon sink decreased by 8.29×10^(4) t C/yr compared with that in 2010 and by 10.83×10^(4) t C/yr compared with that in 2000.High-carbon sinks were found mainly in mountainous areas,whereas low-carbon sinks are concentrated in urban con-struction land,rural residential areas,and land margins.2)From 2000 to 2020,the spatial security pattern of carbon metabolism tended to be‘high in the middle of the east and west and low in the gulf.’In 2000,2010,and 2020,16 stable carbon sinks were identified.The carbon energy flow density in Guangxi was greater than that in Guangdong and Hainan,with positive carbon flow corridors located primarily in Guangxi and Guangdong.The number of carbon sequestration nodes remained stable at approximately 15,mainly in Guangxi and Hainan.3)Scenario simulations revealed that under the Nature-based mild restoration scenario,the carbon sink rate will reach 611.85×10^(4) t C/yr by 2030 and increase to 612.45×10^(4) t C/yr by 2060,with stable carbon sinks increasing to 18.In the restora-tion scenario based on Anti-globalization,the carbon sink will decrease from 610.24×10^(4) t C/yr in 2030 to 605.19×10^(4) t C/yr in 2060,with the disappearance of some positive carbon flow corridors and stable carbon sinks.Under the Human-based sustainable restoration scenario,the carbon sink area will decrease from 607.00×10^(4) t C/yr in 2030 to 596.39×10^(4) t C/yr in 2060,with carbon sink areas frag-menting and positive carbon flow corridors becoming less dense.4)On the basis of the current and predicted CMSSPs,this study ex-plores spatial ecological restoration strategies for high-carbon storage areas in bay urban agglomerations at four levels:the land control region,urban agglomeration structure system,carbon sink structure and bay structure control region.
基金supported by the National Natural Science Foundation(Nos.52000024 and 41907335)the Natural Science Foundation of Shanghai(No.23ZR1400700).
文摘The arsenic(As)release from sediments in great lakes is affected by various factors.In this study,the characteristics of As release fromsediments was investigated,and the As sources and sinks with the strengths in sediments from different areas(grass-type,algae-type,and grass-algae alternation areas)in great shallow lakes(Taihu Lake,China)were analyzed,and the influence of P competition in the process of As release was also studied.The results showed that changing trend of the values of equilibrium As concentration in sediments were consistent with the regional changes(0 to 28.12μg/L),and the sediments from algaetype areas had the higher values.The sediments from western lake and northwest lake bay were a strong As and a weak P source,and the north lake bay had the opposite trend of these two regions.Intense P source competition with As from the sediments occurred in algae-type areas.The grass-type areas had strong As and P retention capacities,indicating a sink role of sediment with high As and P sorption capacities.The degree of As and P saturation had similar trend in sediments,and the grass-type areas had the higher values,18.3%-21.4%and 15.31%-20.34%,respectively.Contribution analysis results showed that most of As release contribution was from the bottom(30-50 cm)sediments,and the surface(0-10 cm)sediments from algae-type areas contributed more to the overlying water than other region.
基金Supported by Science and Technology Commissioner Project of Tianjin Science and Technology Bureau(22ZYCGSN00630).
文摘[Objectives]To assess the carbon sink capacity in seawater suspension cage aquaculture of shellfish in Tianjin from 2015 to 2022.[Methods]The carbon sink capacity of different shellfish species was evaluated using both physical and value assessment methods.[Results]The shellfish cultivated in seawater suspension cages in Tianjin exhibited a significant capacity for carbon sinks.The amounts of carbon removed by suspension cage aquaculture of Rapana venosa,Crassostrea gigas,Scapharca subcrenata,Scapharca broughtonii and Argopectens irradias were 448.297,403.398,89.463,40.657,and 106.719 t,respectively.Furthermore,the total volume of shellfish cultivated in seawater exhibited a consistent upward trend over time,correlating with an annual increase in the amount of carbon removed.Among the shellfish cultivated in seawater suspension cages,the order of carbon sink capacity was as follows:C.gigas>R.venosa>A.irradias>S.subcrenata and S.broughtonii.In terms of the carbon sink capacity of soft tissues,the ranking was as follows:A.irradias>R.venosa>C.gigas>S.subcrenata and S.broughtonii.The structural and yield factors associated with seawater suspension cage aquaculture of shellfish significantly influenced the enhancement of the total carbon sink of cultivated shellfish.Notably,structural factors had a greater impact on the increase in the carbon sink of cultivated shellfish compared to total yield factors.[Conclusions]The findings will serve as a reference for enhancing the carbon sink potential of fisheries and achieving sustainable development in seawater aquaculture in Tianjin.
基金supported by the Recovery and Resilience Plan(PRR)and by European Funds Next Generation EU under the Project“AET—Alliance for Energy Transition,”no.C644914747-00000023,investment project no.56 of the Incentive System“Agendas for Business Innovation”.
文摘The experimental analysis takes too much time-consuming process and requires considerable effort,while,the Artificial Neural Network(ANN)algorithms are simple,affordable,and fast,and they allow us to make a relevant analysis in establishing an appropriate relationship between the input and output parameters.This paper deals with the use of back-propagation ANN algorithms for the experimental data of heat transfer coefficient,Nusselt number,and friction factor of water-based Fe_(3)O_(4)-TiO_(2) magnetic hybrid nanofluids in a mini heat sink under magnetic fields.The data considered for the ANN network is at different Reynolds numbers(239 to 1874),different volume concentrations(0%to 2.0%),and different magnetic fields(250 to 1000 G),respectively.Three types of ANN back-propagation algorithms Levenberg-Marquardt(LM),Broyden-Fletcher-Goldfarb-Shanno Quasi Newton(BFGS),and Variable Learning Rate Gradient Descent(VLGD)were used to train the heat transfer coefficient,Nusselt number,and friction factor data,respectively.The ANOVA t-test analysis was also performed to determine the relative accuracy of the three ANN algorithms.The Nusselt number of 2.0%vol.of Fe_(3)O_(4)-TiO_(2) hybrid nanofluid is enhanced by 38.16%without a magnetic field,and it is further enhanced by 88.93%with the magnetic field of 1000 Gauss at a Reynolds number of 1874,with respect to the base fluid.A total of 126 datasets of heat transfer coefficient,Nusselt number,and friction factor were used as input and output data.The three ANN algorithms of LM,BFGS,and VLGD,have shown good acceptance with the experimental data with root-mean-square errors of 0.34883,0.25341,and 1.0202 with correlation coefficients(R2)of 0.99954,0.9967,and 0.94501,respectively,for the Nusselt number data.Moreover,the three ANN algorithms predict root-mean-square errors of 0.001488,0.005041,and 0.006924 with correlation coefficients(R2)of 0.99982,0.99976,and 0.99486,respectively,for the friction factor data.Compared to BFGS and VLGD algorithms,the LM algorithm predicts high accuracy for Nusselt number,and friction factor data.The proposed Nusselt number and friction factor correlations are also discussed.
文摘The accelerated pace of natural and human-driven climate change presents profound challenges for Earth's systems.Oceans and ice sheets are critical regulators of climate systems,functioning as carbon sinks and thermal reservoirs.However,they are increasingly vulnerable to warming and greenhouse gas emissions.
基金supported by the Basic Research Funds for the Central Government“Innovative Team of Zhejiang University”under contract number(2022FZZX01-09).
文摘Data center cooling systems are substantial energy consumers,and managing the heat generated by electronic devices is becoming more complex as chip power levels continue to rise.The single-phase immersion cooling(SPIC)server with oil coolant is numerically investigated using the validated Re-Normalization Group(RNG)k-εmodel.For the investigated scenarios where coolant velocity at the tank inlet is 0.004 m/s and the total power is 740 W,the heat transfer between the heat sinks and the coolant is dominated by natural convection,although forced convection mediates the overall heat transfer inside the tank.The maximum velocity of coolant through the heat sink is 0.035 m/s and the average heat transfer coefficient is up to 75.8 W/(m2·K).The geometry of the heat sink is important for the cooling performance.Increasing both the fin thickness and number enhances the natural convection effect of the heat sink,but also increases the flow resistance.The heat sink with a fin thickness of 3 mm performs the best,reducing the average graphics processing unit(GPU)temperature from 71.3℃ to 68.6℃.A heat sink with an optimal fin number of 16 reduces the average GPU temperature to 67.7℃.As for the effect of fin height,increasing it from 15 to 30 mm results in increases in the heat transfer area and flow rate by about 72%and 32%,respectively,which reduces the average GPU temperature to 65.2℃.Therefore,the importance of fin parameters ranks in the following order:fin height,number,and thickness.This study highlights the potential application of oil coolants in SPIC systems and offers theoretical guidance for the efficient design of natural convection cooling solutions.
基金financially supported by the National Natural Science Foundation of China(32192435)the Application and Demonstration Project of Network Security and Informatization Technology,Chinese Academy of Sciences(CAS-WX2022SF-0101)+1 种基金the Liaoning Provincial Key Research and Development Program(2023021230-JH2/1018)the Youth Innovation Promotion Association of CAS(2023205).
文摘Climate change is the most severe ecological challenge faced by the world today.Forests,the dominant component of terrestrial ecosystems,play a critical role in mitigating climate change due to their powerful carbon sequestration capabilities.Meanwhile,climate change has also become a major factor affecting the sustainable management of forest ecosystems.Climate-Smart Forestry(CSF)is an emerging concept in sustainable forest management.By utilizing advanced technologies,such as information technology and artificial intelligence,CSF aims to develop innovative and proactive forest management methods and decision-making systems to address the challenges of climate change.CSF aims to enhance forest ecosystem resilience(i.e.,maintain a condition where,even when the state of the ecosystem changes,the ecosystem functions do not deteriorate)through climate change adaptation,improve the mitigation capabilities of forest ecosystems to climate change,maintain high,stable,and sustainable forest productivity and ecosystem services,and ultimately achieve harmonious development between humans and nature.This concept paper:(1)discusses the emergence and development of CSF,which integrates Ecological Forestry,Carbon Forestry,and Smart Forestry,and proposes the concept of CSF;(2)analyzes the goals of CSF in improving forest ecosystem stability,enhancing forest ecosystem carbon sequestration capacity,and advocating the application and development of new technologies in CSF,including artificial intelligence,robotics,Light Detection and Ranging,and forest digital twin;(3)presents the latest practices of CSF based on prior research on forest structure and function using new generation information technologies at Qingyuan Forest,China.From these practices and reflections,we suggested the development direction of CSF,including the key research topics and technological advancement.
文摘Kinetics of the gas-phase reactions of•OH radicals with a series of fluoroesters were studied for the first time at 298±3 K and atmospheric pressure.Relative rate coefficients were determined by in situ FTIR spectroscopy in nitrogen and GC-FID in air to monitor the decay of reactants and references.The following coefficient values(in 10^(−12)cm^(3)/(molecule•sec))were obtained for ethyl fluoroacetate(EFA),ethyl 4,4,4-trifluorobutyrate(ETB),and butyl fluoroacetate(BFA),respectively:k_(1)(EFA+OH)=1.15±0.25 by FTIR and 1.34±0.23 by GC-FID;k_(2)(ETB+OH)=1.61±0.36 by FTIR and 2.02±0.30 by GC-FID;k_(3)(BFA+OH)=2.24±0.37 by FTIR.Reactivity trends were developed and correlated with the number of CH_(3)and F substituents in the fluoroester,and structure-activity relationships(SARs)calculations were performed.In addition,the tropospheric lifetimes of EFA,ETB,and BFA upon degradation by OH radicals were calculated to be 9,6,and 5 days,respectively,indicating that these fluorinated compounds could have a possible regional effect from the emission source.Relatively small photochemical ozone creation potentials of 9,7,and 19 were estimated for EFA,ETB,and BFA,respectively.The GlobalWarming Potentials(GWPs)for EFA,ETB,and BFA were calculated for different time horizons.For a 20-year time horizon,the GWPs were 1.393,0.063,and 0.062,respectively.In the case of a 100-year time horizon,the GWPs were 0.379,0.017,and 0.017,and for a 500-year time horizon,the GWPs were 0.108,0.005,and 0.005 for EFA,ETB,and BFA.
基金supported by the China National Funds for Distinguished Young Scholars(Grant No.12025204)the Shanghai Municipal Education Commission(Grant No.2019-01-07-00-09-E00018)。
文摘Suppressing micro-amplitude vibrations is a critical issue in aerospace engineering.While nonlinear energy sinks(NES)are effective for passive vibration damping,their performance diminishes for micro-amplitude vibrations.This paper introduces a motion-amplified NES(MANES)to address this challenge.The system’s governing equations are derived using Hamilton’s principle,and an approximate analytical solution is validated by numerical methods.The effects of various parameters are explored,with higher vibration reduction efficiency achievable through parameter adjustments.Compared to cubic NES,MANES shows superior vibration suppression and a broader reduction bandwidth for micro-amplitude excitations.Additionally,MANES enters the effective vibration reduction range at lower excitation levels,indicating a reduced threshold for vibration suppression.This study provides insight into the vibration suppression mechanism of MANES,offering a theoretical foundation for mitigating micro-amplitude vibrations in engineering applications.
基金supported by the Outstanding Action Plan of Chinese Sci-tech Journals(Grant No.OAP-C-077).
文摘Forests play a critical role in mitigating cli-mate change by sequestering carbon,yet their responses to environmental shifts remain complex and multifaceted.This special issue,“Tree Rings,Forest Carbon Sink,and Climate Change,”compiles 41 interdisciplinary studies exploring forest-climate interactions through dendrochro-nological and ecological approaches.It addresses climate reconstruction(e.g.,temperature,precipitation,isotopes)using tree-ring proxies,species-specific and age-dependent growth responses to warming and drought,anatomical adap-tations,and methodological innovations in isotope analysis and multi-proxy integration.Key findings reveal ENSO/AMO modulation of historical climates,elevation-and latitude-driven variability in tree resilience,contrasting carbon dynamics under stress,and projected habitat shifts for vulnerable species.The issue underscores forests’dual role as climate archives and carbon regulators,offering insights for adaptive management and nature-based climate solutions.Contributions bridge micro-scale physiological processes to macro-scale ecological modeling,advancing sustainable strategies amid global environmental challenges.
基金The Major Science and Technology Plan of Hainan Province under contract No.ZDKJ2021008the Hainan Provincial Natural Science Foundation of China under contract No.623RC456+1 种基金the Hainan Province Science and Technology Special Fund under contract Nos ZDYF2021SHFZ064 and ZDYF2022SHFZ056the Collaborative Innovation Center of Marine Science and Technology in Hainan University under contract No.XTCX2022HYC19.
文摘The exchange of inorganic nutrients at the coastal sediment-water interface(SWI)plays a crucial role in regulating the nutrient budget in overlying water.The related studies mainly focus on the mid-to high-latitude regions,leaving a significant gap in the quantitative assessment of nutrient exchange and environmental controls at the SWI in lowlatitude coastal regions.We quantitatively assess the exchange of inorganic nutrients at the SWI in three tropical bays(Dongzhai Harbor,Xiaohai Lagoon,Qinglan Harbor).Sediments act as a source of ammonium,phosphate,and silicate,but for nitrate,sediments can be both a source and sink,although with substantial spatial and temporal variations in their fluxes.Labile organic matter is a critical regulator for the fluxes of inorganic nutrients at the SWI.The sedimentary nutrients input with high N/P molar ratio will alter the nutrient stoichiometry to mitigate the nitrogen limitation in coastal waters.However,the internal sediment release in these tropical bays plays a relative weak role in contributing to the nutrient addition in comparison with the other external nutrient sources including riverine input,submarine groundwater discharge,and atmospheric deposition.According to the global compilation on SWI nutrient fluxes,we propose that water column primary production and external inputs to interpret the variation in exchange and fluxes of nutrients at the SWI in different ecosystems.Such a conceptual understanding of these chain biogeochemical processes involving external nutrient input,primary production,particulate organic matter settling,and the accumulation and release of inorganic nutrients in sediments will be helpful for the scientific-based pollution prevent and control in coastal waters.
基金National Natural Science Foundation of China,No.42071415National Key Research and Development Program of China,No.2021YFE0106700Outstanding Youth Foundation of Henan Natural Science Foundation,No.202300410049。
文摘China is the world's largest carbon dioxide(CO_(2)) emitter and a major trading country. Both anthropogenic and natural factors play a critical role in its carbon budget. However,previous studies mostly focus on evaluating anthropogenic emissions or the natural carbon cycle separately, and few included trade-related(import and export) CO_(2) emissions and its contribution on global warming. Using the Carbon Tracker CT2019 assimilation dataset and China trade emissions from the Global Carbon Project, we found that the change trend of global CO_(2) flux had obvious spatial heterogeneity, which is mainly affected by anthropogenic CO_(2) flux. From 2000 to 2018, carbon emissions from fossil fuels in the world and in China all showed an obvious increasing trend, but the magnitude of the increase tended to slow down.In 2018, the radiative forcing(RF) caused by China's import and export trade was-0.0038 W m^(-2), and the RF caused by natural carbon budget was-0.0027 W m^(-2), offsetting 1.54% and 1.13% of the RF caused by fossil fuels that year, respectively. From 2000 to 2018, the contribution of China's carbon emission from fossil fuels to global RF was 11.32%. Considering China's import and export trade, the contribution of anthropogenic CO_(2) emission to global RF decreased to 9.50%. Furthermore, taking into account the offset of carbon sink from China's terrestrial ecosystems, the net contribution of China to global RF decreased to 7.63%. This study demonstrates that China's terrestrial ecosystem and import and export trade are all mitigating China's impact on global anthropogenic warming, and also confirms that during the research process on climate change, comprehensively considering the carbon budget from anthropogenic and natural carbon budgets is necessary to systematically understand the impacts of regional or national carbon budgets on global warming.
文摘As a vital component of the national economic system,the forestry economy plays a significant role in promoting economic and social development.With the increasing emphasis on green and sustainable development,the carbon sink market has gained widespread attention and experienced rapid expansion,exerting a profound impact on the sustainable development of the forestry economy.In this new stage,deepening the relationship between the carbon sink market and the forestry economy is of great practical significance for enhancing forest coverage,advancing forestry economic growth,and fostering green ecological development.This paper analyzes the impact of the carbon sink market on the sustainable development of the forestry economy and explores specific strategies for its advancement.
基金supported by the National Natural Science Foundation of China(Nos.42475125,42105117,42021004 and 41975143)the National Key R&D Program of China(Nos.2019YFA0607202 and 2020YFA0607501)+4 种基金Jiangsu Science Foundation for Distinguished Young Scholar(No.BK20220055)the 333 Project of Jiangsu Province(No.BRA2017402)the R&D Foundation of Jiangsu Province,China(No.BK20220020)Zhejiang Provincial Basic Public Welfare Research Project(No.LGF22D050004)the Key Laboratory of Ecosystem Carbon Source and Sink,China Meteorological Administration(ECSSCMA).
文摘China is the largest emitter of anthropogenic CO_(2) globally,with its cities recognized as significant emission hotspots.Consequently,evaluating anthropogenic CO_(2) emissions and the carbon neutral capability(CNC)of Chinese cities is critical for climate change mitigation.Despite this importance,no studies to date have assessed recent and future city-scale CNCs using the top-down atmospheric inversion approach,revealing substantial knowledge gaps regarding regional CO_(2) budgets.To address these issues,this research focused on Hangzhou,a megacity known for having the highest forest cover among China’s provincial capitals,as study region.Year-round atmospheric CO_(2) concentration measurements were conducted from December 2020 to November 2021 at two sites:one urban and one suburban.These observations,along with their difference,were utilized to derive city-scale posterior anthropogenic CO_(2) emissions and to evaluate recent and future CNCs.Our key findings are as follows:(1)The manufacturing industry,energy industry and oil refineries/transformation industry were identified as the largest contributors to urban-suburban CO_(2) difference,accounting for 36.5%,21.3%,and 16.6%,respectively.Additionally,82.5%,65.2%,81.2%and 86.3%of total anthropogenic CO_(2) enhancements were attributed to emissions within Hangzhou city in winter,spring,summer and autumn,respectively.(2)The posterior annual anthropogenic CO_(2) emission for Hangzhouwas estimated at 4.65(±0.72)×10^(10) kg/a,indicating significant biases among different prior CO_(2) emission inventories.The annual biological CO_(2) sink,derived from multiple products,was estimated at-0.48(±0.16)×10^(10) kg.(3)The calculated CNC for 2021was 10.3%±3.4%,highlighting a substantial gap towards achieving full carbon neutrality.Considering potential increases in ecosystem carbon sinks due to forest age and uncertainties from climate change,it was predicted that at least 65.2%-82.6%of anthropogenic CO_(2) emissions must be reduced to achieve the goal of full carbon neutrality by year of 2060.
