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.

Microplastic Impacts on Greenhouse Gases Emissions in Terrestrial Ecosystems

Microplastics can influence global climate change by regulating the emissions of greenhouse gases from different ecosystems. The effects of microplastics in terrestrial ecosystems are still not well studied particularly greenhouse gases emissions. Thus, we conducted a laboratory experiment over a period of 90 days with two types of microplastics (differing in their chemical structure), high density polyethylene (HDPE) and low density polyethylene (LDPE), which were applied to the soil at a rate of 0% to 0.1% (w/w). The overarching aim was to investigate the effects of microplastic type, microplastic concentration and days of exposure on greenhouse gases emissions. We also used original and artificially weathered microplastics (the same HDPE and LDPE) to make a comparison of greenhouse gases emissions between the original microplastics treated soils and the soils treated with weathered microplastics. Our findings showed that HDPE and LDPE microplastics significantly increased the emissions of greenhouse gases from the soil than that of the control soils. Emissions were increased with the increases in the level of microplastic in the soil. The weathered microplastic emitted greater quantity of greenhouse gases compared to that of the original microplastics. In contrast to a low initial emission quantity, the emissions were gradually increased at the termination of the experiment. Our experiment on the emissions of greenhouse gases from the soil vis-à-vis microplastic additions indicated that the microplastic increased the emissions of greenhouse gases in terrestrial ecosystems, and pervasive microplastic impacts may have consequences for the global climate change. Greenhouse gases emissions from the soil not only depend on the type and concentration of the microplastic, but also on the days of exposure to the microplastic.

Recovery of greenhouse gas as cleaner fossil fuel contributes to carbon neutrality

Under the context of carbon neutrality of China,it is urgent to shift our energy supply towards cleaner fuels as well as to reduce the greenhouse gas emission.Currently,coal is the main fossil fuel energy source of China.The country is striving hard to replace it with methane,a cleaner fossil fuel.Although China has rich geological resources of methane as coal bed methane(CBM)reserves,it is quite challenging to utilize them due to low concentration.The CBM is however mainly emitted directly to atmosphere during coal mining,causing waste of the resource and huge contribution to greenhouse effect.The recent work by Yang et al.demonstrated a potential solution to extract low concentration methane selectively from CBM through using MOF materials as sorbents.Such kind of materials and associated separation technology are promising to reduce greenhouse gas emission and promote the methane production capability,which would contribute to carbon neutrality in dual pathways.

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 reduction of co-benefit-type wastewater treatment system for fish-processing industry: A real-scale case study in Indonesia

This study examined the application of co-benefit-type wastewater treatment technology in the fish-processing industry. Given that there was a dearth of information on fish-processing industrial wastewater in Indonesia, site surveys were conducted. For the entire fish-processing industry throughout the country, the dissemination rate of wastewater treatment facilities was less than 50%. Using a co-benefit approach, a real-scale swim-bed technology (SBT) and a system combining an anaerobic baffled reactor (ABR) with SBT (ABR–SBT) were installed in a fishmeal processing factory in Bali, Indonesia, and the wastewater system process performance was evaluated. In a business-as-usual scenario, the estimated chemical oxygen demand load and greenhouse gas (GHG) emissions from wastewater from the Indonesian fish-processing industry were 33 000 tons per year and 220 000 tons of equivalent CO_(2) per year, respectively. On the other hand, the GHG emissions in the co-benefit scenarios of the SBT system and ABR–SBT system were 98 149 and 26 720 tons per year, respectively. Therefore, introducing co-benefit-type wastewater treatment to Indonesia’s fish-processing industry would significantly reduce pollution loads and GHG emissions.

Effects of Superphosphate Addition on NH_3 and Greenhouse Gas Emissions During Vegetable Waste Composting

To study the effects of superphosphate（SP） on the NH_3 and greenhouse gas emissions,vegetable waste composting was performed for 27 days using 6 different treatments. In addition to the controls,five vegetable waste mixtures（0.77m^3 each） were treated with different amounts of the SP additive, namely, 5%, 10%,15%, 20% and 25%. The ammonia volatilization loss and greenhouse gas emissions were measured during composting.Results indicated that the SP additive significantly decreased the ammonia volatilization and greenhouse gas emissions during vegetable waste composting. The additive reduced the total NH_3 emission by 4.0% to 16.7%. The total greenhouse gas emissions（CO_2-eq） of all treatments with SP additives were decreased by 10.2% to 20.8%, as compared with the controls. The NH_3 emission during vegetable waste composting had the highest contribution to the greenhouse effect caused by the four different gases.The amount of NH_3（CO_2-eq）from each treatment ranged from 59.90 to 81.58 kg/t; NH_3（CO_2-eq） accounted for 69% to 77% of the total emissions from the four gases. Therefore, SP is a cost-effective phosphorus-based fertilizer that can be used as an additive during vegetable waste composting to reduce the NH_3 and greenhouse gas emissions as well as to improve the value of compost as a fertilizer.

Mitigation of greenhouse gases released from mining activities:A review

Climate changes that occur as a result of global warming caused by increasing amounts of greenhouse gases(GHGs)released into the atmosphere are an alarming issue.Controlling greenhouse gas emissions is critically important for the current and future status of mining activities.The mining industry is one of the significant contributors of greenhouse gases.In essence,anthropogenic greenhouse gases are emitted directly during the actual mining and indirectly released by the energy-intensive activities associated with mining equipment,ore transport,and the processing industry.Therefore,we reviewed both direct and indirect GHG emissions to analyze how mining contributes to climate change.In addition,we showed how climate change impacts mineral production.This assessment was performed using a GHG inventory model for the gases released from mines undergoing different product life cycles.We also elucidate the key issues and various research outcomes to demonstrate how the mining industry and policymakers can mitigate GHG emission from the mining sector.The review concludes with an overview of GHG release reduction and mitigation strategies.

Preparation of activated carbons and their adsorption properties for greenhouse gases:CH_4 and CO_2

Three kinds of activated carbons were prepared using coconut-shells as carbon precursors and characterized by XRD, FT-IR and texture property test. The results indicate that the prepared activated carbons were mainly amorphous and only a few impurity groups were adsorbed on their surfaces. The texture property test reveals that the activated carbons displayed different texture properties, especially the micropore size distribution. The adsorption capacities of the activated carbons were investigated by adsorbing CH4, CO2, N2 and O2 at 25 ？C in the pressure range of 0-200 kPa. The results reveal that all the activated carbons had high CO2 adsorption capacity, one of which had the highest CO2 adsorption value of 2.55 mmol/g at 200 kPa. And the highest adsorption capacity for CH4 of the activated carbons can reach 1.93 mmol/g at 200 kPa. In the pressure range of 0-200 kPa, the adsorption capacities for N2 and O2 were increased linearly with the change of pressure and K-AC is an excellent adsorbent towards the adsorption separation of greenhouse gases.

Deep placement of nitrogen fertilizer increases rice yield and nitrogen use efficiency with fewer greenhouse gas emissions in a mechanical direct-seeded cropping system

Deep placement of nitrogen fertilizer is a key strategy for improving nitrogen use efficiency. A two-year field experiment was conducted during the early rice growing seasons(March–July) of 2016 and 2017.The experimental treatments comprised two rice cultivars: Wufengyou 615(WFY 615) and Yuxiangyouzhan(YXYZ), and three N treatments: mechanical deep placement of all fertilizers as basal dose at 10 cm soil depth(one-time deep-placement fertilization, namely OTDP fertilization);manual surface broadcast(the common farmer practice) of 40% N fertilizer at one day before sowing(basal fertilizer)followed by broadcast application of 30% each at tillering and panicle initiation stages;and no fertilizer application at any growth stage as a control. One-time deep-placement fertilization increased grain yield of both rice cultivars by 11.8%–19.6%, total nitrogen accumulation by 10.3%–13.1%, nitrogen grain production efficiency by 29.7%–31.5%, nitrogen harvest index by 27.8%–30.0%, nitrogen agronomic efficiency by 71.3%–77.2%, and nitrogen recovery efficiency by 42.4%–56.7% for both rice cultivars, compared with the multiple-broadcast treatment. One-time deep-placement fertilization reduced CH4-induced global warming potential(GWP) by 20.7%–25.3%, N2O-induced GWP by 7.2%–12.3%, and total GWP by 14.7%–22.9% for both rice cultivars relative to the multiple-broadcast treatment. The activities of glutamine synthetase and nitrate reductase were increased at both panicle-initiation and heading stages in both rice cultivars following one-time deep-placement fertilization treatment. Larger leaf area index at heading stage and more favorable root morphological traits expressed as larger total root length, mean root diameter, and total root volume per hill were also observed. One-time deep-placement fertilization could be an effective strategy for increasing grain yield and nitrogen use efficiency and lowering greenhouse-gas emissions under mechanical direct-seeded cropping systems.

Changes in Grain Yield of Rice and Emission of Greenhouse Gases from Paddy Fields after Application of Organic Fertilizers Made from Maize Straw

A field experiment was conducted at the farm of Yangzhou University, Yangzhou, China, to study the effects of organic fertilizers made from maize straw on rice grain yield and the emission of greenhouse gases. Four organic fertilizer treatments were as follows： maize straw （MS）, compost made from maize straw （MC）, methane-generating maize residue （MR）, and black carbon made from maize straw （BC）. These organic fertilizers were applied separately to paddy fields before rice transplanting. No organic fertilizer was applied to the control （CK）. The effects of each organic fertilizer on rice grain yield and emission of greenhouse gases were investigated under two conditions, namely, no nitrogen （N） application （ON） and site-specific N management （SSNM）. Rice grain yields were significantly higher in the MS, MC and MR treatments than those in CK under either ON or SSNM. The MS treatment resulted in the highest grain yield and agronomic N use efficiency. However, no significant difference was observed for these parameters between the BC treatment and CK. The changes in the emissions of methane （CH4） carbon dioxide （CO2）, or nitrous oxide （N20） from the fields were similar among all organic fertilizer treatments during the entire rice growing season. The application of each organic fertilizer significantly increased the emission of each greenhouse gas （except N20 emission in the BC treatment） and global warming potential （GWP）. Emissions of all the greenhouse gases and GWP increased under the same organic fertilizer treatment in the presence of N fertilizer, whereas GWP per unit grain yield decreased. The results indicate that the application of organic fertilizer （MS, MC or MR） could increase grain yield, but also could enhance the emissions of greenhouse gases from paddy fields. High grain yield and environmental efficiency could be achieved by applying SSNM with MR.

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.

Response of Mode Water and Subtropical Countercurrent to Greenhouse Gas and Aerosol Forcing in the North Pacific

The response of the North Pacific Subtropical Mode Water and Subtropical Countercurrent (STCC) to changes in greenhouse gas (GHG) and aerosol is investigated based on the 20th-century historical and single-forcing simulations with the Geo-physical Fluid Dynamics Laboratory Climate Model version 3 (GFDL CM3). The aerosol effect causes sea surface temperature (SST) to decrease in the mid-latitude North Pacific, especially in the Kuroshio Extension region, during the past five decades (1950-2005), and this cooling effect exceeds the warming effect by the GHG increase. The STCC response to the GHG and aerosol forcing are opposite. In the GHG (aerosol) forcing run, the STCC decelerates (accelerates) due to the decreased (increased) mode waters in the North Pacific, resulting from a weaker (stronger) front in the mixed layer depth and decreased (increased) subduction in the mode water formation region. The aerosol effect on the SST, mode waters and STCC more than offsets the GHG effect. The response of SST in a zonal band around 40?N and the STCC to the combined forcing in the historical simulation is similar to the response to the aerosol forcing.

Greenhouse gas emissions from shallow uncovered coal seams

This study discusses a method of quantifying emissions from surface coal mining that has been trialled in Australia. The method is based on direct measurement of surface emissions from uncovered coal seams in mine pits, concurrent measurement of residual gas content of blasted coal in mine pits, and measurement of pre-mining gas content of the same seam from cores retrieved from exploration boreholes drilled away from active mining. The results from one of the mines studied are presented in this paper. In this mine,the pre-mining gas content of the target seam was measured using cores from an exploration borehole away from active mining. Gas content varied from 0.7 to 0.8 m3/t and gas composition varied from16% to 21% CH4(84–79% CO2). In-pit measurements included seam surface emissions and residual gas content of blasted and ripped coal. Residual gas content varied from 0.09 to 0.15 m3/t, less than twofold across the mine pit. Composition of the residual gas was in general 90% CO2and 10% CH4, with slight variation between samples. Coal seam surface emissions varied from 1.03 to 7.50 mL of CO2-e per minute and per square meter of the coal seam surface, a sevenfold variation across the mine pit.

Greenhouse gas emissions from pig and poultry production sectors in China from 1960 to 2010

Pig and poultry production in China had experienced considerable changes from 1960 to 2010. The present study aimed to evaluate the effects of these changes on greenhouse gas emission inventeries （expressed as CO2 equivalent） from these two sectors. The inventories included methane emissions from enteric fermentation, methane and nitrous oxide production from manure management. The greenhouse gas emissions from these sources in 2010 in pig sector were 17, 62 and 21%, respectively, and that in poultry sector （including chicken, duck, goose and others） were 1, 18 and 81%, respectively. Total CO2 equivalent increased from 1960 to 2010 in both pig （11 582 to 55564 Gg yr-1） and poultry （1 497 to 14 873 Gg yr-1） sectors. Within poultry sector, emissions from chicken, duck, goose and others accounted for 74, 15, 11 and 0.01% in 2010, respectively. However, during the last 50 years, these emissions continuously reduced when related to production of I kg of pork （8.01 to 1.14 kg kg-1）, poultry meat （1.19 to 0.37 kg kg-1） and egg （0.47 to 0.33 kg kg-1）, which is mainly associated with the continuous improvement in production efficiency in all management systems. These results provide benchmark information for Chinese authorities to develop appropriate policies and mitigation strategies to reduce greenhouse gas emissions from pig and poultry sectors.

Effects of plastic film mulching on soil greenhouse gases(CO2,CH4 and N2O) concentration within soil profiles in maize fields on the Loess Plateau,China

To better understand the effects of plastic film mulching on soil greenhouse gases（GHGs） emissions,we compared seasonal and vertical variations of GHG concentrations at seven soil depths in maize（Zea mays L.） fields at Changwu station in Shaanxi,a semi-humid region,between 2012 and 2013.Gas samples were taken simultaneously every one week from non-mulched（BP） and plastic film-mulched（FM） field plots.The results showed that the concentration of GHGs varied distinctly at the soil-atmosphere interface and in the soil profile during the maize growing season（MS）.Both carbon dioxide（CO_2） and nitrous oxide（N_2O） concentrations increased with increasement of soil depth,while the methane（CH_4）concentrations decreased with increasement of soil depth.A strong seasonal variation pattern was found for CO_2 and N_2O concentrations,as compared to an inconspicuous seasonal variation of CH_4 concentrations.The mean CO_2 and N_2O concentrations were higher,but the mean CH_4 concentration in the soil profiles was lower in the FM plots than in the BP plots.The results of this study suggested that plastic film mulching significantly increased the potential emissions of CO_2and N_2O from the soil,and promoted CH_4 absorption by the soil,particularly during the MS.

Life Cycle Assessment,Estimation and Comparison of Greenhouse Gas Mitigation Potential of New Energy Power Generation in China

From the perspective of life cycle assessment （LCA）, the development, construction, and operation of all kinds of new energy power generation technologies release greenhouse gas （GHG） emissions. This sparks concerns about the lowcarbon nature of the new energy power generation technologies. Based on national and international literature review, this paper estimates and compares the GHG emission factors of traditional thermal power generation and new energy power generation technologies in China with the LCA approach. The GHG mitigation potential of new energy power generation technologies as substitution for traditional thermal power generation in China was evaluated, according to the objectives of new energy power generation of the national development planning. The results show that the GHG emission factors of new energy power generation axe much lower than that of traditional thermal power generation even with LCA accounting, and the GHG mitigation potential of new energy substitution is huge.

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%.

Development of National Greenhouse Gas Emissions Inventories in the Context of International Climate Negotiations

Based on the principle of common but differentiated responsibilities, the UNFCCC has different requirements on national GHG inventories submitted by Annex I and non-Annex I parties. Since 2007, the transparency of mitigation actions by developing countries, the submission frequency of national communications cored on national inventory and the relevant international consultation and analysis have become the key issues in climate negotiations. Relevant responsibilities of developing countries showed an increasing trend. Through the analysis of these different requirements, particularly on technical review system of national inventories on developed countries and of the current situation of China's inventory development, the challenges faced by China are identified and the corresponding countermeasures are also put forward, including improving institutional arrangements and statistic system, building country-specific and comprehensive database and preparing for time-series inventory development.

Energy Consumption and Greenhouse Gas Emission of Korean Offshore Fisheries

This paper presents the energy and greenhouse gas(GHG) emission assessments of Korean offshore fisheries. The consumption of energy by fisheries is a significant concern because of its attendant environmental effect, as well as the cost of the fuel consumed in fishing industry. With the global attention of reducing GHG emission and increasing energy efficiency of fuel, the seafood industry needs to further understand its energy use and reduce its GHG emission. In the present study, the amount of energy consumed and the GHG emission of Korean offshore fisheries in a period from 2009 to 2013 were examined. Offshore fisheries accounted for 24% of Korean production in 2013 and 60% of fuel consumption related GHG emission. Whereas the total GHG emission intensity of this sector improved slightly between 2009 and 2012; as such emission decreased by approximately 1.9%, which increased again in 2013. The average amount of total GHG emission in this five years period was 1.78 × 10~6 tons of carbon dioxide equivalent/year(tCO_2eq. y^(-1)). Active fishing gear was found to consume 20% more fuel than passive gear. However, the production from passive gear was 28%, lower than 72% from active gear. The reason for this is that less abundant stationary resources are harvested using passive gear. Furthermore, the consumption of fuel was significantly influenced by the fishing method. Implementation and development of new fishing technologies and methods are important for improving energy efficiency and reducing the climate impact on fisheries. To realize these purposes, the fishery management system needs to be established by centralizing on energy efficiency and climate effect.

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.