Abstract:Driven by the country's goal of achieving carbon peak and carbon neutrality and to cope with global climate change,the Grass-based Livestock Husbandry (abbreviated as GLiH) must take into account green ecology in order to achieve high-quality development.The life cycle of the GLiH starts from pasture planting and forage grass processing,to animal husbandry,livestock product processing and transportation,then to consumption and ends at waste treatment,all of which are related to carbon emissions.Based on the Material Flow Analysis (MFA),this study constructed the framework of the GLiH research,and analyzed the characteristics,influencing factors and existing problems related with carbon sources and sinks in different links.In view of the key influencing links within the GLiH research framework,some feasible approaches for the ecological development of GLiH were discussed under the carbon neutrality target,which include enhancing the carbon sink of grassland vegetation,regulating the carbon source of livestock production,and improving the efficiency of clean energy.In addition,multi-sectoral joint technical research is needed to systematically plan and advance the green and low-carbon GLiH,thus to provide support for achieving the national carbon neutral targets.

Abstract:The orchard production system is recognized as a source of greenhouse gas (GHG) emissions,but it's also a sector to reduce emissions and increase sinks through soil carbon sequestration.By calculating the net GHG balance and greenhouse gas intensity (GHGI) per unit product of orchard production system under traditional and optimized managements,then identifying the main GHG emission paths and their carbon mitigation potentials,we can provide scientific evidence for the green and low-carbon management of the orchard production system.In this study,we carried out a meta-analysis on the fertilizer input,yield,net GHG balance and GHGI results of 307 conventionally managed orchards and 333 orchards with optimized management measures,both of which were classified into six categories according to the dominating fruit planted:citrus,apple,pear,grape,banana and other fruits.The results showed that the orchard production systems under optimized management have advantages in yield and GHG reduction due to their optimized practices such as nitrogen fertilizer reduction,organic fertilizer application,irrigation reduction,irrigation cycle control,and fertigation.Whether under traditional or optimized management,the net GHG balance of different orchard production systems was ranked as banana > pear > apple > grape > other > citrus,nevertheless,the net GHG balance was significantly reduced by 53.2%-75.8% by the optimized management.Similarly,the GHGI decreased from range of 2.82±0.20 kg(CO₂-eq)·kg^-1-4.32±0.27 kg(CO₂-eq)·kg^-1 under traditional management to range of 0.64±0.19 kg(CO₂-eq)·kg^-1-1.40±0.13 kg(CO₂-eq)·kg^-1 under optimized measures.The dominant components of GHG emissions from orchard production systems were CO₂-eq from nitrogen fertilizer inputs during their production and transportation,N₂O emissions induced by nitrogen application,and CO₂-eq from energy consumption of irrigation machines.GHG emissions from orchard production systems in China can be offset by 38.4% to 66.9% through enhancing soil organic carbon capacity by optimization practices such as straw returning,cover crops and no-tillage.Therefore,China's orchard production system has a large potential in carbon emission reduction.In view of the increasing fruit consumption in the future,GHG emissions from orchard production should be and can be mitigated by optimizing management measures,thus to facilitate the carbon peaking and carbon neutralization targets.

Abstract:Paddy fields are an important source of methane (CH₄) and nitrous oxide (N₂O) emissions.In this study,an in-situ rice field experiment was carried out to investigate the influence of different organic manures on rice yield and greenhouse gas emissions in a typical double-cropping rice field in the Pearl River Delta region.The treatments included no fertilizer (CK),chemical fertilizer (CF),stack organic fertilizer (SOF),rapidly composted organic fertilizer (COF),fresh organic fertilizer (FOF),and sterilized organic fertilizer (STOF).The five fertilization treatments were applied equally at nitrogen level.The static chamber-gas chromatography was used to measure greenhouse gas fluxes in this study.The results are as follows:1) The order of rice yields was STOF>FOF>COF>CF>SOF>CK.Compared with chemical fertilizer treatment,the rice yields under STOF,FOF,and COF increased by 19.3％,17.1％,and 15.5％ (P<0.05),respectively,and their economic benefits increased by 41.2％,69.4％,and 24.2％,respectively.2) The total emissions of CH₄ in the double-cropping rice seasons were in the order of COF>FOF>SOF>STOF>CF>CK.Compared with chemical fertilizer treatments,the total emissions of CH₄ increased by 333.5％,261.3％,154.1％,and 128.6％ under the treatments of COF,FOF,SOF,and STOF,respectively (P<0.05).3) During the rice growing period,the CH₄ was still the main greenhouse gas in this region since the N₂O emissions of various fertilizer treatments were at a low level.4) Compared with chemical fertilizer,the four organic fertilizers significantly increased the global warming potential and greenhouse gas intensity of rice fields.From the perspective of the whole life cycle,the COF has shorter composting time and less greenhouse gas emission,and thus is more economical and environment friendly.

Abstract:In this paper,a threshold regression model with panel data of 203 prefecture-level cities in China's mainland from 2011 to 2019 is constructed to analyze the relationship between the level of enterprise's Financial Technology (FinTech) development and non-CO₂ greenhouse gas emissions.The structural characteristics and regional heterogeneity of FinTech impact on enterprise's non-CO₂ greenhouse gas emissions were verified.It is found that the FinTech development presents a significant pollution reduction effect and can suppress non-CO₂ greenhouse gas emissions.Specifically,the industrial sulfur dioxide emission reduction is emphasized when the enterprise's FinTech level is low,while the industrial nitrogen oxide emission reduction capacity enhances when the FinTech level is high.In addition,there is a structural effect of the level of FinTech on the role of enterprise's pollution emission reduction.Compared with the depth of FinTech usage and the degree of financial digitalization,the breadth of FinTech coverage poses significantly stronger influence on the emission reduction of non-CO₂ greenhouse gases.Moreover,regional differences are found in the effect of FinTech on non-CO₂ greenhouse gases emission reduction,where it is more significant in the central region than in the eastern and western regions.The results of the study have implications for the implementation of differentiated FinTech development strategies,as well as for the promotion of comprehensive green transformation of socio-economic development,and the achievement of the "double carbon" goal.

Abstract:On a 100-year time scale,the global warming potential of methane (CH₄) is 25 times that of CO₂.Revealing the spatiotemporal dynamics of CH₄ emissions and the composition of emission sources is of great value for the realization of the national dual-carbon goal.Based on the data set in the Emissions Database for Global Atmospheric Research (EDGAR),this paper characterizes the spatiotemporal distribution characteristics of CH₄ emissions in China,and uses spatial autocorrelation and hotspot analysis methods to reveal the spatial agglomeration effect of CH₄ emissions.The data were analyzed for CH₄ emission sources.The results show that the hotspots of CH₄ emissions from 1970 to 2018 mainly distributed in East China,North China and South China,and had a trend of gradually extending to the northwest region.In general,there were three stages from gradual rise to rapid rise and then stable emission;from the perspective of emissions in each administrative region,Shanghai has always been at the highest level,with average emission in ten years being not less than 25 t·km^-2;energy activities and industrial production contributed most to CH₄,especially the transportation and coal mining sectors which held gradually increasing proportions of emissions in recent years.The research results can provide effective guidance for exploring industry emission reduction plans and practicing low-carbon paths.

Abstract:Spatio-temporal change characteristics and driving factors of methane (CH₄) concentration are important to the study of global climate change.Yet few reports have been found to reveal the variation characteristics of methane concentration on different time scales and the contribution of potential climate drivers in the tropics.In this study,based on GHGsat methane concentration products,the seasonal variation characteristics of methane concentration were analyzed by taking Hainan Island as a typical tropical study area.In addition,this study determined the sensitivity of temporal and spatial distribution of methane to climatic factors in Hainan Island,and also analyzed the contribution of climate factors and topographic factors to methane concentration by using Boosted Regression Trees (BRT).The results showed that methane concentration in Hainan Island had significant seasonal variations,which was a significant downward trend from April to August and a significant upward trend from September to December;spatially,the areas with high methane concentration were mainly clustered around coastline,while low methane concentration area was mainly distributed in the middle of Hainan Island.The results of the univariate linear regression model showed that there was a weak positive correlation between air temperature and methane concentration,and a weak negative correlation between rainfall and methane concentration.The results of BRT showed that the contribution of altitude,rainfall and air temperature to methane concentration distribution is 71.95％,20.52％ and 5.66％,respectively.This study can provide a scientific basis for the contribution of climatic factors to methane emissions.

Abstract:This paper used CH4MOD model and emission factor method to calculate and analyze the CH₄ emission from agricultural activities in Yunnan province,and used scenario analysis to project the agricultural CH₄ emission in Yunnan province.The results showed that the total agricultural CH₄ emission in Yunnan province rose in fluctuation,followed by a sharp decrease,and then remained stable from 2010 to 2019,in which the emission from animal intestinal fermentation contributed the most.From 2010 to 2019,the agricultural emission intensity of CH₄ per unit agricultural added value in Yunnan province showed a downward trend,while the agricultural emission intensity per unit agricultural land area was fluctuating.The CH₄ emission from agricultural activities in Yunnan province was projected to be in upward trends under three scenarios from 2020 to 2029.Therefore,CH₄ emission reduction measures should be taken in rice cultivation,livestock and poultry breeding in order to achieve the goal of "double carbon" and build a beautiful China.

Abstract:Rice straw and pig manure are the important exogenous organic substances for the improvement of Soil Organic carbon (SOC) storage capacity in upland red soil.Different amounts of rice straw and pig manure with equal carbon were mixed with tested soils and incubated indoor for 235 days,after which the SOC was divided into Particulate Organic carbon (POM),Sand & stable Aggregate carbon (S+A),Dissolved Organic Carbon (DOC),readily oxidizable organic carbon (s+c-rSOC) and inert organic carbon (rSOC) components according to the physiochemical fractionation method,and then various SOC fractions were reclassified as the Decomposable Plant Material (DPM),Resistant Plant Material (RPM),Humified organic matter (HUM),microbial biomass (BIO) and Inert Organic Matter (IOM) based on the RothC model.The results show that the soil Total Carbon (TC) and various organic carbons were significantly increased by the equal-carbon additions of rice straw and pig manure,but the effect of rice straw addition on the TC,DPM,RPM and IOM was significant higher than that of pig manure,while its effect on the BIO and HUM was significantly lower than that of pig manure.As the incubation continued,the proportion of IOM in TC gradually increased,while the proportions of DPM,RPM,BIO and HUM in TC gradually decreased.The increase of f-Fe₂O₃ could significantly increase the DOC in upland red soil (P<0.05).The increase of a-Fe₂O₃ could significantly promote the decrease of DOC and the increase of IOM component (P<0.05),while the increase of a-Al₂O₃ could significantly increase the POM,BIO and HUM (P<0.05),and significantly reduce the DOC (P<0.01).It can be concluded that in short term,the addition of rice straw with equal carbon content is more beneficial to the storage of TC,DPM,RPM and IOM (rSOC),while the addition of pig manure is more beneficial to the storage of BIO and HUM.However,with the prolonging of the incubation time,the active carbon pools such as DOC,IOM (rSOC) and chemically protected carbon pools in upland red soil would significantly increase by the equal-carbon additions of rice straw and pig manure.

Abstract:In order to clarify the effects of microbial agents combined with urea on reactive gaseous nitrogen (N₂O and NH₃) emissions and vegetable yield,a field experiment was designed to simultaneously measure N₂O and NH₃ fluxes using the static opaque chamber-gas chromatograph and ventilation chamber-ammonia capture method,respectively.Three following field treatments were set up including control (CK),urea (U),and urea combined with microbial agents (EM).The results showed that compared with CK treatment,the U treatment increased vegetable yield as well as reactive gaseous nitrogen emissions,though the increase trends were not significant.However,the combination of microbial agents with urea markedly enhanced both the vegetable yield and reactive gaseous nitrogen emissions (P<0.05),specifically,the vegetable yield,cumulative N₂O emission,cumulative NH₃ emission,reactive gaseous nitrogen emission and emission intensity were significantly increased by 22.28%,103.46%,45.07%,92.80% and 57.14%,respectively.It can be concluded that,besides the economic benefits by increasing vegetable yield,the enhancement of reactive gaseous nitrogen emissions and the resulting environmental losses need to be carefully evaluated for application of microbial agents in vegetable fields.

Abstract:Agricultural land consolidation is closely related to aspects of regional food security,ecological protection,and sustainable economic development.This paper evaluated the potential of agricultural land consolidation in Pucheng county of Fujian province,aiming to provide data basis and planning references for the comprehensive land consolidation work in Pucheng.The potential of agricultural land consolidation was measured by an index system and methods of deviation standardization,entropy weight,and K-means clustering.According to the comprehensive potential score,Pucheng’s agricultural land consolidation can be ranked into four grades,and the consolidation work can be carried out according to respective functional zones including agricultural tourism,agricultural economy,agricultural ecology and agricultural production.The consolidation potential is high in central and eastern regions,and slightly lower in the northern regions than in the southern regions.It can be concluded that Pucheng county has potential in agricultural land consolidation though there are differences in spatial distribution,and the insufficient consolidation potential in some regions can be attributed to restrictions by ecological space and population density,which can be offset by stimulating endogenous potential and improving ecological service function.In addition,the planning of agricultural land consolidation should pay attention to the coherence and integrity of the consolidation areas.

Abstract:Rice is the largest grain crop in China,and its unique flooded paddy soil provides necessary condition for the occurrence of denitrification.However,the problems of nitrogen utilization decline and greenhouse gas emissions caused by denitrification have gained increasing concern.As a biological process driven by microorganisms,denitrification is affected by many factors such as soil pH and organic carbon sources.To reveal the effect of exogenous organic carbon on the functional activity and potential of denitrifying microorganisms in paddy soils with different pH values,this study added glucose to two paddy soils with different initial pH values and analyzed the abundance of key functional genes (nirK/S,nosZ) for denitrification at DNA and RNA levels.The results showed that the glucose reduced soil pH,the degree of which rose with the increase of the glucose concentration.The added glucose also enhanced soil denitrification,which was observed only in alkaline paddy soil.The responses of number and expression of nirK and nirS genes to glucose addition were significantly different between the two soils with different pH values,and the response degree of nirK gene was relatively higher.In acidic paddy soil,the number and expression of nosZ gene decreased with the increase of carbon source concentration;while in alkaline paddy soil,low concentration glucose significantly stimulated the number and expression of nosZ gene,but high concentration glucose caused soil acidification,which then inhibited the number and expression of nosZ gene.This study shows that exogenous organic carbon source affects the function and activity of denitrifying microorganisms in paddy soil from aspects of carbon source supply and soil acidification,which in turn influences the occurrence of denitrification and subsequent nitrous oxide emission.

Abstract:The proposal of carbon peak and carbon neutrality goals will have a transformative impact on the socio-economic development of China.It is of great significance to clarify the agricultural N₂O emissions for the realization of the dual carbon goal.Here,we calculate the N₂O emissions from agricultural system using China's crop planting and manure management data from 2000 to 2019,use the Theil index to explore the difference in N₂O emission among four major regions and eight economic zones,and propose suggestions for China's low-carbon production of staple grains.The results showed an increasing then decreasing trend in N₂O emissions from China's agricultural system during 2000-2019.The N₂O emissions increased during 2000-2015 from 699,800 tons in 2000 to 860,100 tons in 2015,and then declined to 764,300 tons in 2019.The N₂O emission significantly varied between provinces,which was 560 tons in Beijing in 2019 and 56 900 tons in Henan in 2019.Along with the concentrated trend,diverse variations in N₂O emission were observed between provinces and regions.The provincial differences first expanded and then narrowed,and have stabilized since 2009.For the eight economic zones,the Theil index showed a downward trend in the northern coast,eastern coast,northwest zone,and an upward trend in other zones.To reduce N₂O emission,it is necessary to carry out low-carbon production of major grains targeted for different regions and economic zones,especially for the central region,western region,northeast zone and southwest zone.

Abstract:Increasing greenhouse gas emissions has become an important factor affecting global warming.The spatial heterogeneity of CH₄ concentration and its relationship with local climate and social economy are important factors affecting the ecological policy formulation.Greenhouse gas emission reduction is a challenging and imperative task for Hainan Island,which is a pilot zone for the national ecological protection drive.Here,the trend and driving factors of CH₄ concentration in Hainan Island during 2020-2021 were analyzed through the Geographically Weighted Regression (GWR) model,which was established by using GHGSat CH₄ product,temperature,rainfall,GDP and population datasets,as well as Theil-Sen trend analysis and Mann-Kendall test.The results showed a slight decreasing trend of CH₄ concentration in Hainan Island from 2020 to 2021 with the mean value of 1 848.40×10^-9 mol／mol;as for its spatial distribution,no obvious variation in 52.95％ areas and a significant decrease in 46.42％ areas were observed in Hainan Island.In addition,the GWR can reveal the response of CH₄ concentration distribution to climate factors on pixel scale,specifically,the regression coefficients between CH₄ concentration and temperature ranged from -114.92 to 127.80,and those between CH₄ concentration and rainfall ranged from -297.40 to 399.91;the regression coefficients of CH₄ concentration with GDP and population were relatively high,ranged at -4 125.55-4 509.07 and -1 751.43-1 556.41,respectively,suggesting possible big impacts of GDP and population on CH₄ concentration distribution.The R² of Ordinary Least Squares (OLS) and GWR for CH₄ concentration with temperature,rainfall,GDP and population were 0.14 and 0.83 respectively,indicating that GWR model outperformed the OLS model in explaining the spatial pattern of CH₄ concentration.This study revealed the trend and driving factors of CH₄ concentration in Hainan Island,thus provides a method guidance for evaluation of the dynamic CH₄ concentration in Hainan.

Abstract:In order to improve the attitude control accuracy and anti-disturbance performance of the quad-rotor UAV,the disturbance observer and the extended state observer are combined,and a sliding mode anti-disturbance control approach based on dual observers is proposed.First,the disturbance with part of the known information is described by the exogenous system model and estimated by the disturbance observer;then the extended state observer is used for the estimation of the complex nonlinear differentiable disturbance;then a sliding mode control law is designed to compensate for the disturbance estimated by the dual observers to achieve attitude control;finally,the stability of the system is proved by the Lyapunov theory.The simulation results show that this method has higher tracking accuracy and better anti-disturbance ability than traditional PID control.