Behaviors of Lanthanum and Cerium on Grain Boundaries in Carbon Manganese Clean Steel

The behaviors of La and Ce on gram boundaries in carbon manganese clean steel were investigated by high-reso- lution transmission elecetron microscope （HRTEM）, scanning elecetron microscopy（SEM ）, energy dispersive spectrometer （EDS） and X-ray diffraction（XRD） analysis. The existing forms of rare earths （RE） in clean steel were as follows： dissolved in sohd solution, forming inclusion or second phase containing RE （RE-Fe-P, La-P, Fe-La eutectic and Fe-Ce phase）. The dissolved La or Ce segregated at grain boundaries. The segregation of both S and P at gram boundaries was reduced with suitable RE content. The impact toughness of the steel was improved obviously. La and Ce had effecets on purifying molten steel and modifying inclusions in clean steel, whereas with excessive La or Ce, La-Fe-P, La-P and Fe-La eutecetic phase or Ce-Fe-P and Fe-Ce intermetallic compound would form along grain boundaries, causing the impact energy to decrease significantly.

A joint use of emergy evaluation, carbon footprint and economic analysis for sustainability assessment of grain system in China during 2000–2015

The rapid growth of grain yield in China accelerates a discussion on whether the grain system in China is sustainable. To answer the question, a comprehensive assessment from economic and environmental points is necessary. This study jointly used economic analysis(ECA), emergy evaluation(EME) and carbon footprint(CF) to analyze the environmental and economic sustainability of the grain production system in China based on the national statistical data during 2000–2015. Results showed that the costs of maize, wheat, rice and soybean had increased by 252-346% from 2000 to 2015, causing the lower profit of grain system in recent years. The situation resulted in a serious problem on economic sustainability of grain system in China. Meanwhile, the emergy sustainability index(ESI) of maize, wheat, rice and soybean systems were increasing during 2000–2015, and the CF on unit yield of the crops had been reduced by 10-30% in the study period. The results reflected the improved environmental sustainability of grain system in China during 2000–2015. Nevertheless, the emergy flow of industrial inputs for the crops were increased by 4-22% in the study period, and the CF from the inputs presented a growth rate of 16-23% as well during the same period. The results implied that the grain system in China was relying more on fossil-based inputs. Finally, according to the key points of cost, emergy and CF, we suggest that improving labor efficiency, advanced agricultural practices and optimizing cropping pattern will be effective ways to further improve the economic and environmental sustainability of grain system in China.

Grain size characteristics of the carbonate-free fraction of surface sediments from the Southwest Indian Ridge area and its geological significance

The carbonate-free fraction of 20 surface sediments collected from the ultraslow-spreading Southwest Indian Ridge(SWIR) was studied by grain size analysis and mineralogical analysis with X-ray powder diffraction(XRD),stereo microscopy and scanning electron microscopy(SEM). The characteristics of the carbonate-free fraction of the sediments were obtained, and related influential factors were discussed. The results show that the mean grain size of this fraction is in 1.96Φ–8.19Φ, with poorly sorting and unimodal, bimodal or irregular bimodal distribution patterns. Four grain size end members of the fraction are derived with the End Member Model method. The finest end member EM1 shows a significant contribution of terrigenous materials of the aeolian input and sediment carried by the bottom current. End member EM2 with medium size mainly reflects sediment of a siliceous bioclast origin. EM3 and EM4 are interpreted as representing the coarser volcanic materials related to bedrock weathering or volcanic activities. Multi-provenance is the dominant factor controlling the grain size pattern of the carbonate-free fraction of the sediments in that area. In addition, sediment transport processes such as the bottom current and wind are the minor factors that influence the grain size distribution of the carbonate-free fraction sediments.

Effect of Strain Rate on the Ferrite Grain Refinement in a Low Carbon Nb-Ti Microalloyed Steel during Low Temperature Deformation

Grain refinement is one of the effective methods to develop new generation low carbon microalloyed steels possessing excellent combination of mechanical properties. The microstructural evolution and ferrite grain refinement at the deformation temperature of 865℃, above Ar3, with different strain rates were investigated using single pass isothermal hot compression experiments for a low carbon Nb-Ti microalloyed steel. The physical processes that occurred during deformation were discussed by observing the optical microstructure and analyzing the true stress-true strain responses. At strain rates of 0.001 and 0.01s^-1, there is no evidence of work hardening behavior during hot deformation and strain-induced transformation （SIT） leads to dynamic flow softening in flow curves. Optical microscopy observation shows that ultrafine and equiaxed ferrite with grain sizes of 2μm can be obtained by applying deformation with strain rate of 0.1 s^-1 due to SIT just after deformation. Furthermore, increasing the strain rate from 0.001 to 0.1 s^-1 reduces both the grain size of the equiaxed ferrite and the amount of deformed ferrite.

Grain refinement of Mg-Al magnesium alloys by carbon inoculation

C2Cl6 was used as grain refiner for AM60 magnesium alloys. The effects of grain refinement process on chemical composition, microstructure, impact energy, hardness and mechanical properties of magnesium alloys were investigated with XRF spectrometer, optical and electronic microscopes, pendulum impact tester, hardness tester and MTS material testing machine. The results show that C2Cl6 has good effects on microstructure and mechanical properties of AM60 magnesium alloys. The optimum usage of C2Cl6 in AM60 for getting the best properties is 1.0%. The results of electronic microscopic examination and theoretical analyses show that Al4C3 should be the potent heterogeneous nucleant for Mg-Al magnesium alloys.

Surface Ferrite Grain Refinement and Mechanical Properties of Low Carbon Steel Plates

Considering the specialities of the steel plate production, the TMCP study has been carried out with Gleeble 2000 tester to explore the possibility of fine grained ferrite in the low carbon steel plates with the chemical composition of C 0.13--0.18, Si 0.12-0.18, Mn 0.50-0. 65, P 0. 010-0. 025, and S 0. 005-0. 028. The plates with thickness of 8. 7 mm in which the ferrite grain size is smaller than 8μm have been produced by special de- formation process in the laboratory. Furthermore, the trial production of special plain carbon steel plates of 16-25 mm in thickness and 2 000- 2 800 mm in width with fine grained ferrite has been successfully carried out in the Shougang Steel Plate Rolling Plant. The ferrite grain size is 5.5-7μm in the surface layers and 9.5-15μm in the central layer respectively. The yield strength is 320- 360 MPa, tensile strength is 440-520 MPa and the elongation is 25%- 34 %. It is very important for the rolling plants to improve the low carbon steel plates＇ mechanical properties. The results show that the ferrite grains in the surface layer can be refined effectively by the appropriate rolling process, and the strength can be also increased.

Grain size composition and transport of sedimentary organic carbon in the Changjiang River(Yangtze River) Estuary and Hangzhou Bay and their adjacent waters

Surface sediments from the Changjiang River （Yangtze River） Estuary, Hangzhou Bay, and their adjacent waters were analyzed for their grain size distribution, organic carbon （OC） concentration, and stable carbon isotope composition （δ13C）. Based on this analysis, about 36 surface sediment samples were selected from various environments and separated into sand （〉0.250 ram, 0.125-0.250 ram, 0.063-0.125 mm） and silt （0.025-0.063 mm） fractions by wet-sieving fractionation methods, and further into silt- （0.004-0.025 mm） and clay-sized （〈0.004 mm） fractions by centrifugal fractionation. Sediments of six grain size categories were analyzed for their OC and 613C contents to explore the grain size composition and transport paths of sedimentary OC in the study area. From fine to coarse fractions, the OC content was 1.18%, 0.51%, 0.46%, 0.42%, 0.99%, and 0.48%, respectively, while the δ13C was -21.64‰, -22.03‰, -22.52‰, -22.46‰, -22.36‰, and -22.28%0, respectively. In each size category, the OC contribution was 42.96%, 26.06%, 9.82%, 5.75%, 7.09%, and 8.33%, respectively. The OC content in clay and fine silt fractions （〈0.025 ram） was about 69.02%. High OC concentrations were mainly found in offshore modern sediments in the northeast of the Changjiang River Estuary, in modern sediments in the lower estuary of the Changjiang River and Hangzhou Bay, and in Cyclonic Eddy modern sediments to the southwest of the Cheju Island. Integrating the distribution of terrestrial OC content of each grain size category with the δ13C of the bulk sediment indicated that the terrestrial organic material in the Changjiang River Estuary was transported seaward and dispersed to the Cyclonic Eddy modern sediments to the southwest of the Cheju Island via two pathways： one was a result of the Changjiang River Diluted Water （CDW） northeastward extending branch driven by the North Jiangsu Coastal Current and the Yellow Sea Coastal Current, while the other one was the result of the CDW southward extending branch driven by the Taiwan Warm Current.

Electrochemical Detection of Zeranol and Zearalenone Metabolic Analogs in Meats and Grains by Screen-Plated Carbon-Plated Disposable Electrodes

Zeranol (Z) is an estrogenic growth-promoting agent synthesized from mycotoxin zearalenone (Zen). Inadvertent consumption of Z and its structural analogs from meat or grain products remain a food safety concern. An economic and rapid high performance liquid chromatography method with electrochemical detection using disposable screen-printed carbon electrode is developed for determination of Z, Zen and 3 major metabolic analogs α-zearalenol (α-Ze), β-zearalenol (β-Ze), and β-zearalanol (β-Za). The electrochemical method was validated for application in food matrices including beef, pork, feed and cereal after optimized liquid and/or solid-phase extraction procedures. All 5 Z analogs were separated in 10 minutes with the limits of detection ranging from 15 ng/ml for α-Ze and 25 ng/ml for Z and Zen;the limit of quantitation ranged from 40 50 ng/ml. The recoveries were all above 75% regardless of matrix types and extraction procedures. The intra and inter day variations were both less than 6% at the nominal concentration of 1 μg/ml and less than 13% at 100 ng/ml level. Chromatographically time-matched peaks of Z, α-Ze and β-Za were observed in moldy feed, cereal and rice with high productivity, indicating possible grain-specific Zs exposure for animals and human. Proper exercise of preservative procedures for grain and grain products to prevent it from mold production is imperative. The simplicity and reproducibility of this method affords quick and reliable quantitation of multiple types of Z analogs in food products and can offer semi-confirmative information comparable to UV detection and supplementary to ELISA screening.

Estimate the influence of snow grain size and black carbon on albedo

Estimation of the influence of snow grain size and black carbon on albedo is essential in obtaining the accurate albedo. In this paper, field measurement data, including snow grain size, snow depth and density was obtained. Black carbon samples were collected from the snow surface. A simultaneous observation using Analytical Spectral Devices was employed in the Qiyi Glacier located in the Qilian Mountain. Analytical Spectral Devices spectrum data were used to analyze spectral re- flectance of snow for different grain size and black carbon content. The measurements were compared with the results obtained from the Snow, Ice, and Aerosol Radiation model, and the simulation was found to correlate well with the ob- served data. However, the simulated albedo was near to 0.98 times of the measured albedo, so the other factors were as- sumed to be constant using the corrected Snow, Ice, and Aerosol Radiation model to estimate the influence of measured snow grain size and black carbon on albedo. Field measurements were controlled to fit the relationship between the snow grain size and black carbon in order to estimate the influence of these factors on the snow albedo.

“双碳”背景下主产区粮食生产减污降碳综合效益评价

基于2002—2021年中国13个粮食主产区的面板数据,采用熵权TOPSIS法、障碍因子诊断模型与Dagum基尼系数,实证分析主产区粮食生产减污降碳综合效益及其时空演化。结果表明:2002—2021年粮食主产区综合效益指数由0.388提高至0.878,整体为上升态势;主产区综合效益水平呈现“东高西低”的空间分布特征;核心障碍因素存在由粮食产出效率与粮食产出水平向粮食生产投入集约化水平与粮食生产碳排放强度集中的转变过程;总体差异水平未出现进一步缓解的趋势,空间差异主要来源于区域间差异,样本期贡献率均值为56.89%,东西部间差异最大,东部、中部地区区域内的基尼系数水平也存在上升趋势,说明缓解区域内差异同样不容忽视。据此,建议切实提高资源投入集约化程度,统筹协调各区域综合效益均衡发展,建立绿色粮食生产体系,强化绿色低碳收益,进而实现农业高质量发展。

Grain refinement of low carbon steel produced by CSP process

In comparison with conventional production for hot strips, compact strip production (CSP) brings about some new micro-structural phenomena. Investigations were carried out to clarify the grain refinement mechanism of low carbon steel strips produced by the EAF-CSP process. Samples, obtained from the same rolling stock during continuous rolling, were examined through SEM, TEM and XEDS. Thin slabs have a dominant columnar structure and the spacing of the secondary dendrite arms ranges from 90 to -125 μm. The average grain sizes for the central area of the samples from the 1st to 6th pass are 41.6, 25.2, 21.4, 20.2, 13.1, 6.7 μm, respectively. Large number of nanometer oxide and sulfide have been found in the low carbon steel produced by the CSP process. The grain refinement mechanism can be summarized as follows: finer solidification structure of the thin slab; austenite recrystalliza-tion at higher temperature and stain accumulation at lower temperature caused by the great reduction of single rolling pass during continuous rolling; nano-scaled precipitates of sulfide and oxide which drag grain boundaries of austenite or ferrite to prevent the grain coarsening.

Tillage, <i>Desmodium intortum</i>, Fertilizer Rates for Carbon Stock, Soil Quality and Grain Yield in Northern Guinea Savanna of Nigeria

Northern Guinea Savanna of Nigeria soils are continuously and intensively cultivated, resulting in soil quality degradation, carbon stock depletion, accelerated soil erosion and soil nutrient depletion. Effects of land use change on soil carbon stocks (SOC) are of concern regarding greenhouse gas emissions mitigation and sustainable crop production, because there is a need for food sufficiency while conserving the environment. Also, managing soils under intensive use and restoring degraded soils are top priorities for a sustained agronomic production while conserving soil and water resources. Hence, this study;“Tillage, Desmodium intortum, fertilizer rates for carbon stock, soil quality and grain yield in Northern Guinea Savanna” is aimed at devising possible mitigating measures for soil quality degradation, carbon stock depletion and impoverished crop yields using Zea mays as test crop. The study was a Randomized Complete Block Design (RCBD) in split-split plot arrangement with four replicates. The four main tillage and Desmodium intortum combination treatments were: 1) Maize &#8722;without Desmodium + Conventional tillage (MC), 2) Maize + Desmodium live-mulch incorporated and relayed + Conservation tillage (MDIC), 3) Maize + Desmodium in no-tillage system (MDNT), 4) Maize + Desmodium in strip tillage (MDST). The main treatment plots were each divided to accommodate four (4) rates of N (60, 80, 100 and 120 kg·ha&#8722;1) as sub plots, while the N rate plots were further divided to accommodate three (3) rates of P (6.6, 13.2, and 26.4 kg·ha&#8722;1) as sub-subplots. Findings support that Desmodium intercrops with Maize treatments (MDIC, MDNT, and MDST) resulted in increased organic carbon contents in 2013, with MDNT resulting in significantly higher organic carbon content (7.37 g·kg&#8722;1 in 2012 and 8.37 g·kg&#8722;1 in 2013) than the other treatments. Also, zero tillage practice (MDNT) sequestered significantly higher carbon stock (18.06 t C ha&#8722;1), followed by minimum tillage (MDIC) that sequestered 15.99 t C ha&#8722;1 than the other treatments. Highest grain yield of 2.61 tha&#8722;1 under MDIC and MDNT was followed by MDST and least under MC. Total score of soil quality assessment gave least score values of 13 under MDIC and MDNT;thus best soil quality (SQ1) was ascribed to the minimum tillage with D. intortum intercrop and relayed (MDIC) and Zero tillage with D. intortum (MDNT) treatments. Maize Strip cropped with D. intortum treatment (MDST) was ranked SQ2.

塔里木盆地富满地区一间房组颗粒滩类型及分布

为明确富满地区中奥陶统一间房组颗粒滩类型及其分布,应用岩心、岩石薄片、碳同位素、测井、地震等资料,对其沉积相及其展布开展了研究。研究区一间房组沉积相类型可分为斜坡—盆地、台地边缘和开阔台地,后两者是颗粒滩的主要发育区;颗粒滩包括砂屑滩、鲕粒滩、生屑滩、过渡类型等,厚度占比普遍大于80%,部分井区大于90%,具浅颗粒滩化,其分布受快速海侵及缓慢海退背景下侧向迁移为主的沉积方式控制。开阔台地大面积分布的砂屑滩及生屑砂屑滩具备良好的储集性能,可作为下一步油气勘探的重要领域。

中国设施农业的减碳增汇效应分析——基于1828个县域面板数据的实证研究

设施农业作为中国现代农业的重要标志,揭示其时空格局演变及减碳增汇效应对实现“双碳”目标、促进绿色转型发展具有重要意义。本文应用空间经济计量方法,采用2013—2017年中国1828个县域面板数据,分析中国县域碳排放、固碳量及设施农业的时空演变特征,在此基础上实证分析了设施农业的减碳增汇效应,并从区域和粮食产区角度进行了异质性分析。结果表明:1)中国县域碳排放总体呈东高西低的空间格局,固碳量则显示出西高东低的特点,设施农业面积空间格局也为东高西低,三者均具有显著的空间正相关性及高-高空间集聚特征。2)设施农业面积对碳排放的直接和间接效应都呈“U”型,存在显著减碳效应,但设施农业面积对固碳量的直接和间接效应都显著为负,增汇效应不明显。3)设施农业面积对于减碳增汇的作用存在显著的异质性。就区域层面而言,设施农业面积显著促进东部和东北部地区碳减排,显著抑制中部和西部地区碳汇;就粮食产区而言,设施农业面积对粮食主产区和主销区存在显著的减碳效应,对三大粮食产区的增汇效应均不明显。研究认为,各县应当加快推进设施农业绿色发展,因地制宜发展低碳农业,加强区域间减碳增汇合作交流,以此有力地推进设施农业绿色可持续发展,实现减碳增汇的愿景。

川西北晚三叠世卡尼期浅水碳酸盐生产工厂构成及其转换过程定量化研究

【目的】准确识别碳酸盐工厂类型并阐明其发育控制因素,定量化评价工厂发育过程的环境条件,厘清其在沉积体系转换过程中的古生态学和沉积学信号是探究碳酸盐岩沉积体系演化的关键。【方法】以川西北绵竹市汉旺镇观音崖剖面的马鞍塘组为例,通过系统的碳酸盐岩微相分析,结合粒径统计分析方法对20391个颗粒定量分析,在此基础上对该时期热带浅水碳酸盐生产工厂的构成、特征、转变过程、驱动因素等进行了详细阐述。【结果】研究区热带浅水碳酸盐生产工厂可进一步划分为似球粒、鲕粒、生屑及生物礁等多个细分特异化工厂类型,指示多样化的碳酸盐生产路径。通过分析研究区热带浅水工厂的构成,沉积环境、水动力条件和营养水平等因素,发现各个细分工厂类型有着非常强烈的“生境”特点,工厂类型的转变更多地受区域海平面变化控制。【结论】频繁的海平面变化导致营养水平、水动力条件和碳酸盐矿物饱和度等因素快速变化,进而驱动了具体细分工厂的转变。而众多细分工厂在沉积序列上的快速变化指示了它们在横向上的共生关系。因此,较短时间尺度下细分工厂类型的转变主要与区域海平面控制的横向生产工厂类型的迁移有关,与极端事件和沉积体系的转变可能无关。

天文旋回约束下东营凹陷中始新统含碳酸盐细粒沉积岩成因分析

【目的】通过对中国东部渤海湾盆地东营凹陷发育的大套具有韵律特征的富含碳酸盐物质和有机质的湖相细粒沉积岩进行深入研究,以期探究其成因机制以及古气候、古环境的变化特征。【方法】基于岩心和薄片观察,依据沉积构造特征和矿物组分含量进行岩相划分。结合沉积环境和沉积速率的差异,将目标层段划分为四个单元,采取Multi-Taper Method(MTM)方法对樊页1井(FY1)沙四上(Esu4)到沙三下(Esl3)亚段的自然伽马(GR)测井曲线进行分段频谱分析。【结果】通过宏观和微观沉积观察,将东营凹陷地区发育的细粒岩划分为纹层状泥质灰岩、纹层状灰质泥岩、弱纹层状灰质泥岩、透镜状泥质灰岩和块状泥岩五种岩相。频谱分析结果显示,四个单元均记录了米兰科维奇旋回信号,包括125 kyr、38.7 kyr和18.7 kyr的周期。基于火山灰测年数据,我们建立了精度为38.7 kyr的“浮动”天文年代标尺,并确定东营凹陷沙四上到沙三下细粒岩沉积的总持续时间为5.3 Myr。进一步分析发现,18.7 kyr岁差旋回与碳酸盐岩含量变化之间存在良好的对应关系,表明地球轨道参数对含碳酸盐细粒沉积岩的沉积作用具有显著影响。【结论】本研究利用旋回地层学理论,从天文周期控制沉积作用的角度,揭示了湖泊沉积的古气候、古环境变化特征。通过分析,我们发现地球轨道参数(特别是18.7 kyr岁差旋回和125 kyr偏心率旋回)共同驱动了气候的变化,进而控制了含碳酸盐细粒沉积岩的沉积作用。具体表现为,在岁差极大值点或偏心率极小值处,日照量增多,湖盆水体温度升高,有利于方解石结晶和灰岩沉积;而在岁差极小值或偏心率极大值处,日照量减少,湖盆水体温度降低,细粒物质主要来自陆源输入,以泥岩沉积为主。这一研究成果对于非常规油气勘探开发具有重要的科学和指导意义。

碳酸盐工厂的精细刻画:定量化重建视角

【意义】碳酸盐工厂为碳酸盐岩沉积体系提供了物质基础,与海洋演化、元素循环、表生地质过程等密切相关,是反映地球系统演化的重要环节。因此,定量化表征碳酸盐工厂及其主控因素是深入理解碳酸盐岩所记录的地质信息的关键。【进展】总结了半定量—定量表征碳酸盐工厂的研究方法进展,结合对沉积过程正演模拟方法的介绍,从定量重建的角度为精细刻画碳酸盐工厂提供了思路。【展望】针对碳酸盐工厂的研究,应在传统碳酸盐岩沉积学的基础上加深对其主控因素的定量评估,特别是直接影响生态的因素。但在套用基于碎屑岩沉积体系所建立的定量分析方法时,需要考虑碳酸盐岩与碎屑岩的差异,并进一步完善适用于碳酸盐岩的模型和分析方法。此外,在应用地球化学指标反演碳酸盐工厂及其主控因素时,要加强对成岩作用改造程度的定量评估,以降低成岩作用对地球化学信号的影响。而在开发和应用新的碳酸盐岩地球化学代用指标时,需明确其赋存或分馏机理,从而更准确地解读其所反映的古气候和古环境信息。同时,在利用沉积过程正演模拟研究工厂的演化和生产机制时,需评估从现代环境中获取的参数在深时地质记录中的适用性,并在建模过程中考虑早期成岩作用及海水化学演化的影响。

中国粮食种植业碳效应时空演化及碳排放公平性

农业低碳转型背景下,准确把握粮食种植业碳效应时空演化及碳排放公平性特征对实现地区生态正义具有重要意义。基于2000—2021年省域面板数据,采用碳排放因子法测算中国30个省区的粮食种植业碳效应,利用核密度估计方法探析时空演化,运用Dagum基尼系数法刻画并解构全国粮食种植业碳排放公平性。研究表明:(1)从时空特征看,粮食种植业碳效应呈现波动上升的净碳汇特征,具体表现为“东强西弱,北高南低”的空间格局,且伴随明显的“马太效应”。在碳效应结构上,秸秆燃烧与玉米种植分别是粮食种植业最主要的碳源与碳汇。(2)从演化趋势来看,全国粮食种植业碳效应的非均衡性呈扩大趋势;在三大主粮中,水稻碳效应非均衡性有所减弱,小麦与玉米碳效应非均衡性均持续上升。(3)从碳排放公平性来看,区域间碳排放差异已成为影响公平性的最主要因素,基尼系数呈“快速上升-波动震荡-缓慢回落”特征,全国粮食种植业碳排放始终处于较公平区间,整体公平性呈改善态势;在三大主粮中,水稻碳排放公平性最低,玉米碳排放公平性最高。最后,提出了采取差异化固碳减排策略、构建低碳发展跨区协作机制、完善碳排放责任分摊机制、探索粮食碳汇交易试点等建议,以期推动我国粮食种植业实现低碳转型发展。

财政激励下主产区粮食低碳生产“稳中求进”策略——基于演化博弈模型的分析

2022年“中央一号文件”提出要牢牢守住保障国家粮食安全这条底线,而提升粮食综合生产能力是国家粮食安全、有效防范和抵御各类风险挑战、促进粮食生态可持续发展和推动农业领域碳排放目标的重要保障。本文以提升粮食综合生产能力、粮食低碳可持续发展能力的财政专项补贴为激励手段,构建粮食主产区政府、粮食生产者和社会组织三方演化博弈模型,通过模拟仿真分析在不同财政激励程度下对提升粮食综合生产能力、粮食低碳生态可持续发展能力的政策影响。研究结果表明:三方博弈主体在财政激励影响下,最终可达到粮食主产区政府激励、粮食生产者支持和社会组织保障的稳定均衡状态。故此,应强化粮食增产财政激励、加强财政转移支付精度、优化财政资金导向作用和注重粮食保障财政倾斜等发展策略,实现粮食低碳生产“稳中求进”。

增产与减碳能否兼得?——粮食主产区设立的农业碳减排效应研究

在粮食安全底线和“双碳”任务双重压力下,准确把握粮食增产政策与农业碳排放的关系,对于推进农业高质量发展具有重要意义。把设立粮食主产区视为一项外生政策干预的准自然实验,运用双重差分法和中介效应模型,考察粮食主产区设立对农业碳排放的影响及其作用机制。研究发现:粮食主产区设立在筑牢粮食安全底线的同时,还对粮食种植环节的农业碳排放具有显著的削减效应,被划定为主产区使得该省份粮食生产碳排放强度和密度分别下降了2.61%和3.58%,而且这一碳排放削减效应表现出逐渐增强的长期动态特征。异质性检验发现,粮食主产区设立对不同来源碳排放的削减效应存在明显差异,对化学制品类排放源削减作用最大,土地利用类排放源次之,化石燃料类排放源不明显。作用机制分析证明,农作物种植结构优化的“结构效应”、粮食种植规模扩大的“规模效应”和农业技术进步的“技术效应”,是粮食主产区设立削减农业碳排放的重要机制,三种效应联合可以解释碳排放削减总效应的64%左右。