Repositioning fertilizer manufacturing subsidies for improving food security and reducing greenhouse gas emissions in China

China removed fertilizer manufacturing subsidies from 2015 to 2018 to bolster market-oriented reforms and foster environmentally sustainable practices.However,the impact of this policy reform on food security and the environment remains inadequately evaluated.Moreover,although green and low-carbon technologies offer environmental advantages,their widespread adoption is hindered by prohibitively high costs.This study analyzes the impact of removing fertilizer manufacturing subsidies and explores the potential feasibility of redirecting fertilizer manufacturing subsidies to invest in the diffusion of these technologies.Utilizing the China Agricultural University Agri-food Systems model,we analyzed the potential for achieving mutually beneficial outcomes regarding food security and environmental sustainability.The findings indicate that removing fertilizer manufacturing subsidies has reduced greenhouse gas(GHG)emissions from agricultural activities by 3.88 million metric tons,with minimal impact on food production.Redirecting fertilizer manufacturing subsidies to invest in green and low-carbon technologies,including slow and controlled-release fertilizer,organic-inorganic compound fertilizers,and machine deep placement of fertilizer,emerges as a strategy to concurrently curtail GHG emissions,ensure food security,and secure robust economic returns.Finally,we propose a comprehensive set of government interventions,including subsidies,field guidance,and improved extension systems,to promote the widespread adoption of these technologies.

Greenhouse gas emission analysis and measurement for urban rail transit: A review of research progress and prospects

Rail transit plays a key role in mitigating transportation system carbon emissions.Accurate measurement of urban rail transit carbon emission can help quantify the contribution of urban rail transit towards urban transportation carbon emission reduction.Since the whole life cycle of urban rail transit carbon emission measurement involves a wide range of aspects,a systematic framework model is required for analysis.This research reviews the existing studies on carbon emission of urban rail transit.First,the characteristics of urban rail transit carbon emission were determined and the complexity of carbon emission measurement was analyzed.Then,the urban rail transit carbon emission measurement models were compared and analyzed in terms of the selection of research boundaries,the types of greenhouse gas(GHG)emissions calculation,and the accuracy of the measurement.Following that,an intelligent station was introduced to analyze the practical application of digital collaboration technology and energy-saving and carbon-reducing system platforms for rail transit.Finally,the urgent problems and future research directions at this stage were discussed.This research presents the necessity of establishing a dynamic carbon emission factor library and the important development trend of system integration of carbon emission measurement and digital system technology.

Greenhouse gas emissions from a constructed wetland for municipal sewage treatment

The fluxes of greenhouse gases (methane and nitrous oxide) emission from a constructed wetland in the Eastern China as municipal sewage treatment were measured from June 1999 to August 2000 by the closed chamber method. The constructed wetland for municipal sewage treatment is a significant source of methane, up to 976 6×10 6 g CH 4/a, which was emitted from the constructed wetland with the area of 495000 m 2 and wastewater loading rate of 12000 m 3/d. Its daily mean methane flux reached 5 22 g CH 4/(m 2·d), 250 times as much as that in natural wetland in the same latitude region. 227 8 mg CH 4 was produced from the treatment of 1 liter wastewater, up to 700—1000 times as much as that in the secondary treatment. The emission of nitrous oxide from the constructed wetland is not higher than that from secondary treatment of wastewater, only 0 07 mgN 2O/L.

Scenario analysis on abating industrial process greenhouse gas emissions from adipic acid production in China

Adipic acid is an important petrochemical product,and its production process emits a high concentration of greenhouse gas N_2 O.This paper aims to provide quantitative references for relevant authorities to formulate greenhouse gas control roadmaps.The forecasting method of this paper is consistent with the published national inventory in terms of caliber.Based on the N_2 O abatement technical parameters of adipic acid and the production trend,this paper combines the scenario analysis and provides a measurement of comprehensive N_2 O abatement effect of the entire industry in China.Four future scenarios are assumed.The baseline scenario(BAUS) is a frozen scenario.Three emission abatement scenarios(ANAS,SNAS,and ENAS) are assumed under different strength of abatement driving parameters.The results show that China's adipic acid production process can achieve increasingly significant N_2 O emission abatement effects.Compared to the baseline scenario,by 2030,the N_2 O emission abatements of the three emission abatement scenarios can reach 207-399 kt and the emission abatement ratios can reach 32.5%-62.6%.By 2050,the N_2 O emission abatements for the three emission abatement scenarios can reach 387-540 kt and the emission abatement ratios can reach 71.4%-99.6%.

Effects of Biochar Application on Soil Properties, Plant Biomass Production, and Soil Greenhouse Gas Emissions: A Mini-Review

Biochar has been applied extensively as a soil amendment over the past decades. This review summarizes the general findings of the impacts of biochar application on different aspects from soil physical, chemical, and microbial properties, to soil nutrient availabilities, plant growth, biomass production and yield, greenhouse gases (GHG) emissions, and soil carbon sequestration. Due to different biochar pyrolysis conditions, feedstock types, biochar application rates and methods, and potential interactions with other factors such as plant species and soil nutrient conditions, results from those studies are not inclusive. However, most studies reported positive effects of biochar application on soil physical and chemical properties, soil microbial activities, plant biomass and yield, and potential reductions of soil GHG emissions. A framework of biochar impacts is summarized, and possible mechanisms are discussed. Further research of biochar application in agriculture is called to verify the proposed mechanisms involved in biochar-soil-microbial-plant interactions for soil carbon sequestration and crop biomass and yield improvements.

Energy return on investment, energy payback time, and greenhouse gas emissions of coal seam gas(CSG) production in China: a case of the Fanzhuang CSG project

The studies and development of coal seam gas（CSG） have been conducted for more than 30 years in China, but few of China＇s CSG projects have achieved large-scale commercial success; faced with the boom of shale gas, some investors are beginning to lose patience and confidence in CSG. China currently faces the following question： Should the government continue to vigorously support the development of the CSG industry？ To provide a reference for policy makers and investors, this paper calculates the EROI_（stnd）[a standardized energy return on investment（EROI） method], EROI_（ide）（the maximum theoretical EROI）, EROI_（3,i）（EROI considering the energy investment in transport）, and EROI_（3,1＋e）（EROI with environmental inputs） of a single vertical CSG well in the Fanzhuang CSG project in the Qinshui Basin. The energy payback time（EPT） and the greenhouse gas（GHG） emissions of the CSG systems are also calculated. The results show that over a 15-year lifetime, EROI_（stnd）, EROI_（ide）, EROI_（3,1）, and EROI_（3,1＋e）are expected to deliver EROIs of approximately11：1, 20：1, 7：1, and 6：1, respectively. The EPT within different boundaries is no more than 2 years, and the life-cycle GHG emissions are approximately 18.8 million kg CO_2 equivalent. The relatively high EROI and short EPT indicate that the government should take more positive measures to promote the development of the CSG industry.

Cooperative prediction method of gas emission from mining face based on feature selection and machine learning

Collaborative prediction model of gas emission quantity was built by feature selection and supervised machine learning algorithm to improve the scientifc and accurate prediction of gas emission quantity in the mining face.The collaborative prediction model was screened by precision evaluation index.Samples were pretreated by data standardization,and 20 characteristic parameter combinations for gas emission quantity prediction were determined through 4 kinds of feature selection methods.A total of 160 collaborative prediction models of gas emission quantity were constructed by using 8 kinds of classical supervised machine learning algorithm and 20 characteristic parameter combinations.Determination coefcient,normalized mean square error,mean absolute percentage error range,Hill coefcient,mean absolute error,and the mean relative error indicators were used to verify and evaluate the performance of the collaborative forecasting model.As such,the high prediction accuracy of three kinds of machine learning algorithms and seven kinds of characteristic parameter combinations were screened out,and seven optimized collaborative forecasting models were fnally determined.Results show that the judgement coefcients,normalized mean square error,mean absolute percentage error,and Hill inequality coefcient of the 7 optimized collaborative prediction models are 0.969–0.999,0.001–0.050,0.004–0.057,and 0.002–0.037,respectively.The determination coefcient of the fnal prediction sequence,the normalized mean square error,the mean absolute percentage error,the Hill inequality coefcient,the absolute error,and the mean relative error are 0.998%,0.003%,0.022%,0.010%,0.080%,and 2.200%,respectively.The multi-parameter,multi-algorithm,multi-combination,and multijudgement index prediction model has high accuracy and certain universality that can provide a new idea for the accurate prediction of gas emission quantity.

Greenhouse gas emission reduction in public buildings according to greenhouse gas reduction policies in Daegu

The issues related to climate change such as depletion of energy resources and continuous high oil prices,global warming,and development of clean energy are adopted and discussed as a national agenda internationally.To cope with these domestic and foreign energy and environmental problems actively,government must prepare prudently in methodology of greenhouse gas reduction.Especially,as energy consumption of buildings accounts for 26 of national consumption,plans to reduce energy consumption of buildings are needed.Each region has a unique nature of energy consumption or consumption patterns,thus an appropriate policy or goal to reduce greenhouse gas (GHG) should be selected.For this,effects on the current policies for GHG as well as nature of energy consumption of buildings should be analyzed.We analyzed quantitatively the effectiveness of policies to reduce GHG emission in public buildings.

Analysis of Agricultural Commodities Value Chains and Greenhouse Gas Emission in Rice and Maize in West Africa: Impact on Food Security

This paper analyses the greenhouse gas (GHG) emission along the value chains of two strategic commodities in West Africa (rice and maize) in four pilot countries: Ghana, Senegal Benin and Cote D’Ivoire. The Value Chains Analysis and Greenhouse model used in this study, provides insight into the relationship between output maximization and GHG emissions to help define optimal intervention approaches that minimize emissions while maximizing the potential yield, hence boost food security. It highlights intervention measures for improvement of production and productivity along with the identification of mitigation measures to reduce GHG emissions. It also revealed that the largest GHG emission factor from maize farming in the selected countries is from the application of nitrogen fertilizers (NO2), and for rice farming, depending on the systems, e.g. rain fed, irrigated or multiple aeration, the emission is mostly due to anaerobic decomposition of methane (CH4) which increases with flooding practice.

Greenhouse gas emissions from Daihai Lake,China:Should eutrophication and salinity promote carbon emission dynamics?

Greenhouse gases(GHGs)emitted or absorbed by lakes are an important component of the global carbon cycle.However,few studies have focused on the GHG dynamics of eutrophic saline lakes,thus preventing a comprehensive understanding of the carbon cycle.Here,we conducted four sampling analyses using a floating chamber in Daihai Lake,a eutrophication saline lake in Inner Mongolia Autonomous Region,China,to explore its carbon dioxide(CO_(2))and methane(CH_(4))emissions.The mean CO_(2)emission flux(FCO_(2))and CH_(4)emission flux(FCH_(4))were 17.54±14.54 mmol/m^(2)/day and 0.50±0.50 mmol/m^(2)/day,respectively.The results indicated that Daihai Lake was a source of CO_(2)and CH_(4),and GHG emissions exhibited temporal variability.The mean CO_(2)partial pressure(p CO_(2))and CH_(4)partial pressure(p CH_(4))were 561.35±109.59μatm and 17.02±13.45μatm,which were supersaturated relative to the atmosphere.The regression and correlation analysis showed that the main influencing factors of p CO_(2)were wind speed,dissolved oxygen(DO),total nitrogen(TN)and Chlorophyll a(Chl.a),whereas the main influencing factors of p CH_(4)were water temperature(WT),Chl.a,nitrate nitrogen(NO_(3)^(-)-N),TN,dissolved organic carbon(DOC)and water depth.Salinity regulated carbon mineralization and organic matter decomposition,and it was an important influencing factor of p CO_(2)and p CH_(4).Additionally,the trophic level index(TLI)significantly increased p CH_(4).Our study elucidated that salinity and eutrophication play an important role in the dynamic changes of GHG emissions.However,research on eutrophic saline lakes needs to be strengthened.

Split Addition of Nitrogen-Rich Substrate at Thermophilic and Mesophilic Stages of Composting: Effect on Green House Gases Emission and Quality of Compost

Composting as a solution to the increasing generation of municipal solid waste (MSW), also contribute to GHGs emission when not controlled and could lack some basic nutrients, especially nitrogen. This study assessed the split-additions of nitrogen-rich substrate to composting materials and their effect on GHGs emissions as well as the quality of the composts. Nitrogen-rich substrates formulated from pig and goat manure were co-composted with MSW for a 12-weeks period by split adding at mesophilic (˚C) and thermophilic (>50˚C) stages in five different treatments. Representative samples from the compost were taken from each treatment for physicochemical, heavy metals and bacteriological analysis. In-situ CH4, CO2, N2O gas emissions were also analyzed weekly during composting. It was observed that all the treatments showed significant organic matter decomposition, reaching thermophilic temperatures in the first week of composting. The absence affects the suitable agronomic properties. All nitrogen-rich substrate applied at thermophilic stage (Treatment two) recorded the highest N, P and K concentrations of 1.34%, 0.97% and 2.45%, respectively with highest nitrogen retention. In terms of GHG emissions, CO2 was highest at the thermophilic stage when N-rich substrate was added in all treatment, while CH4 was highest in the mesophilic stage with N-rich substrate addition. N2O showed no specific trend in the treatments. Split addition of the N-rich substrate for co-composting of MSW produced compost which is stable, has less nutrient loss and low GHG emissions. Split addition of a nitrogen-rich substrate could be an option for increasing the fertilizer value of MSW compost.

Effect of rice cultivar on greenhouse-gas emissions from rice-fish co-culture

In aquaculture,co-culturing rice with fish may mitigate greenhouse-gas emissions.In this study,co-culture of four rice cultivars in a laboratory-scale rice–fish system reduced CH_(4)and N_(2)O emissions relative to fish monoculture.Differences in CH_(4)and N_(2)O emissions among rice cultivars primarily stem from the differential effects of rice plants on plant-mediated CH_(4)transport,CH_(4)oxidation and nitrogen absorption.

Energy use efficiency and greenhouse gas emissions(GHG)analysis of garlic cultivation in Turkey

This study has been conducted with the purpose of determining energy use efficiency and greenhouse gas emissions of garlic cultivation during the 2020-2021 cultivation season in Adıyaman province of Turkey.Questionnaires,observations and field works were performed in 134 garlic farms in the region through simple random method.In garlic cultivation,energy input was calculated as 32103.20 MJ/hm^(2)and energy output was calculated as 30096 MJ/hm^(2).With regards to the three highest inputs in garlic production,46.66%of the energy inputs consisted of chemical fertilizers energy(14979.26 MJ/hm^(2)),11.29%consisted of farmyard manure energy(3625.71 MJ/hm^(2))and 10.48%consisted of human labour energy(3363.36 MJ/hm^(2)).Energy use efficiency,specific energy,energy productivity and net energy in garlic cultivation were calculated as 0.94,1.71 MJ/kg,0.59 kg/MJ,and−2007.20 MJ/hm^(2),respectively.The total energy input consumed in garlic cultivation was classified as 27.19%direct energy,72.81%indirect energy,35.17%renewable energy and 64.87%nonrenewable energy.Total GHG emissions and GHG ratio were calculated as 8636.60 kg CO_(2)-eq/hm^(2)and 0.46 kg CO_(2)-eq/kg,respectively.

Determination of energy use efficiency and greenhouse gas emissions in peach production

The purpose of this study was to determine the energy use efficiency and greenhouse gas(GHG)emissions in peach production that took place in Kırklareli province of Turkey during the 2020-2021 production season.This study included calculations of energy input,energy output,energy use efficiency,specific energy,energy productivity,net energy,energy input types,GHG emissions and GHG ratio.Survey,observation and data calculations are related to the 2020-2021 production season.The data obtained from the study were collected from 16 different farms(reachable)through face-to-face surveys with full count method.Energy input and energy output were calculated as 19570.58 MJ/hm^(2) and 19471.94 MJ/hm^(2),respectively.With regards to production inputs,55.70% of the energy inputs consisted of chemical fertilizers energy(10900.03 MJ/hm^(2)),9.46% consisted of chemicals energy(1852.10 MJ/hm^(2)),9.32% consisted of human labour energy(1823.13 MJ/hm^(2)),7.65% consisted of electricity energy(1497.28 MJ/hm^(2)),6.91% consisted of diesel fuel energy(1351.52 MJ/hm^(2)),4.73% consisted of irrigation water energy(926.10 MJ/hm^(2)),3.43% consisted of machinery energy(671.98 MJ/hm^(2)),1.88% consisted of transportation energy(367.72 MJ/hm^(2)),0.88% consisted of farmyard manure energy(171.80 MJ/hm^(2))and 0.05%consisted of lime energy(8.94 MJ/hm^(2)).Energy use efficiency,specific energy,energy productivity and net energy were calculated as 0.99,1.91 MJ/kg,0.52 kg/MJ and-98.64 MJ/hm^(2),respectively.The consumed total energy input in production was classified as 28.60% direct energy,71.40% indirect energy,14.93% renewable energy and 85.07% non-renewable.Total GHG emissions and GHG ratio were calculated as 1683.24 kgCO_(2)-eq/hm^(2) and 0.16 kg CO_(2)-eq/kg,respectively.

Evaluation of greenhouse gas emission reduction potential of a demand–response solution:a carbon handprint case study of a virtual power plant

The transition towards zero-carbon energy production is necessary to limit global warming.Smart energy systems have facilitated the control of demand-side resources to maintain the stability of the power grid and to provide balancing power for increasing renewable energy production.Virtual power plants are examples of demand–response solutions,which may also enable greenhouse gas(GHG)emission reductions due to the lower need for fossil-based balancing energy in the grid and the increased share of renewables.The aim of this study is to show how potential GHG emission reductions can be assessed through the carbon handprint approach for a virtual power plant(VPP)in a grid balancing market in Finland.According to our results,VPP can reduce the hourly based GHG emissions in the studied Finnish grid systems compared with the balancing power without the VPP.Typical energy sources used for the balance power are hydropower and fossil fuels.The reduction potential of GHG emissions varies from 68%to 98%depending on the share of the used energy source for the power balancing,thus VPPs have the potential to significantly reduce GHG emissions of electricity production and hence help mitigate climate change.

Assessments on emergy and greenhouse gas emissions of internal combustion engine automobiles and electric automobiles in the USA

Increasing energy consumption in the transportation sector results in challenging greenhouse gas(GHG)emissions and environmental problems.This paper involved integrated assessments on GHG emissions and emergy of the life cycle for the internal combustion engine(ICE)and electric automobiles in the USA over the entire assumed fifteen-year lifetime.The hotspots of GHG emissions as well as emergy indices for the major processes of automobile life cycle within the defined system boundaries have been investigated.The potential strategies for reducing GHG emissions and emergy in the life cycle of both ICE and electric automobiles were further proposed.Based on the current results,the total GHG emissions from the life cycle of ICE automobiles are 4.48 E+07 kg CO2-e which is320 times higher than that of the electric automobiles.The hotspot area of the GHG emissions from ICE and electric automobiles are operation phase and manufacturing process,respectively.Interesting results were observed that comparable total emergy of the ICE automobiles and electric automobiles have been calculated which were 1.54 E+17 and 2.20 E+17 sej,respectively.Analysis on emergy index evidenced a better environmental sustainability of electric automobiles than ICE automobiles over the life cycle due to its higher ESI.To the authors’knowledge,it is the first time to integrate the analysis of GHG emissions together with emergy in industrial area of automobile engineering.It is expected that the integration of emergy and GHG emissions analysis may provide a comprehensive perspective on eco-industrial sustainability of automobile engineering.

A study of emissions and marker gases from smouldering combustion in Larix gmelinii plantations of the Daxing'an Mountains

Underground fires are characterized by smouldering combustion with a slow rate of spread rate and without flames.Although smouldering combustion releases large amounts of gaseous pollutants,it is difficult to discover by today's forest fire monitoring technologies.Carbon monoxide(CO),nitrogen oxides(NO_(x))and sulfur dioxide(SO_(2))were identified as high concentration marker gases of smouldering combustion-easily-be monitored.According to a two-way ANOVA,combustion time had a significant impact on CO and NO_(x) emissions;smoldering-depth also had a significant impact on NO_(x) emissions but not on CO emissions.Gas emission equations were established by multiple linear regression,C_(co)=156.989-16.626 t and C_(NOx)=3.637-0.252 t-0.039 h.

Excessive greenhouse gas emissions from wastewater treatment plants by using the chemical oxygen demand standard

Chemical oxygen demand(COD)is widely used as an organic pollution indicator in wastewater treatment plants.Large amounts of organic matter are removed during treatment processes to meet environmental standards,and consequently,substantial greenhouse gases(GHGs)such as methane(CH_(4))are released.However,the COD indicator covers a great amount of refractory organic matter that is not a pollutant and could be a potential carbon sink.Here,we collected and analysed COD data from 86 worldwide municipal wastewater treatment plants(WWTPs)and applied a model published by the Intergovernmental Panel on Climate Change to estimate the emission of CH_(4) due to recalcitrant organic compound processing in China’s municipal wastewater treatment systems.Our results showed that the average contribution of refractory COD to total COD removal was55%in 86 WWTPs.The amount of CH_(4) released from the treatment of recalcitrant organic matter in 2018 could have been as high as 38.22 million tons of carbon dioxide equivalent,which amounts to the annual carbon sequestered by China’s wetlands.This suggests that the use of COD as an indicator for organic pollution is undue and needs to be revised to reduce the emission of GHG.In fact,leaving nontoxic recalcitrant organic matter in the wastewater may create a significant carbon sink and will save energy during the treatment process,aiming at carbon neutrality in the wastewater treatment industry.

Current status of greenhouse gas emissions from aquaculture in China

Aquaculture and mariculture are becoming an increasingly important source of food supply in many countries and regions.However,with the expansion of aquaculture and mariculture comes increasing emissions of greenhouse gases(GHG)which contribute to global warming and climate change.China leads the world in aquaculture and mariculture production,but there are no studies that systematically assess China's overall carbon footprint from these industries.This study quantified GHG emissions from aquaculture and mariculture by four source phases(feed,energy use,nitrous oxide and fertilizers),and then analyzed the carbon footprint of each of these phases for GHG production of nine major species groups over the past ten years to show the spatial distribution of GHG emissions from aquaculture and mariculture in China.Our results showed that the production of feed materials contributed most to the GHG emissions and found that crop energy use,crop land use changes(LUC),fertilizer production,crop nitrous oxide production and rice methane production were the main sources of feed emissions.The total GHG emissions of the nine species groups were 112 Mt(10^(9) kg)CO_(2)e,the nine species accounting for approximately 86%of aquaculture and mariculture production.GHG emissions of cyprinids had the highest contribution at 47%.Spatial analysis based on our study showed Guangdong,Hubei,Jiangsu and Shandong had the highest GHG emissions of all the provinces in this study,and they accounted for approximately 46%of all emissions.The regional Gross Domestic Product(GDP)was significantly positively correlated with GHG emissions in every province,with a correlation coefficient higher than 0.6.Our results showed for the first time the relationship between the relative production by species composition and spatial distribution of GHG emissions from aquaculture and mariculture in China.Our findings provide the scientific basis for reduction of GHG emissions within a broader context of expanding aquaculture in the future.

Changes in Stratospheric Cl O and HCl Concentrations Under Different Greenhouse Gas Emission Scenarios

In this study, comparison of model results and satellite observations reveals that the Whole-Atmosphere Community Climate Model （WACCM-3） reasonably well reproduced the distributions and seasonal vari- ations of C10 and HC1 concentrations. In three greenhouse gas emission scenarios （A1B, A2, and B1）, the C10, C1, C1ONO2, and HC1 concentrations would gradually decrease with time as emissions of ozone depleting substances （ODS） steadily decrease. The rates of the changes in the C10, C1, C1ONO2, and HC1 concentrations are different in the same emission scenario and the rates of change in the same composition concentration are different for different emission scenarios. The C10, C1, and C1ONO2 concentrations de- crease fastest in scenario A2, next fastest in scenario A1B, and slowest in scenario B1. In contrast, the HC1 concentration decreases fastest in scenario B1. The ozone concentration recovers quickly, and is highest in scenario A2. The results show that a rapid decrease in the C10 concentration is an important reason for the accelerated recovery of the ozone layer in scenario A2.