The Emission Reduction Potential of Non-CO_2 Greenhouse Gases in China and Its Policy Implications

Using the improved Energy-Environmental Version of the GTAP Model (GTAP-E) and the sixth version of emission database of non-CO2 greenhouse gases, we simulate the emission reduction potential of non-CO2 greenhouse gases in China and its policy implications. The results show that at present, China is a country with the greatest emission of non-CO2 greenhouse gases in the world, and the emission will account for about 20% of the world's total emission in 2020. The proportion of emission of non-CO2 greenhouse gases from the agricultural sector reaches 73%. In the next 10 years, the emission of non-CO2 gases from cattle and sheep, industry and service industry will experience the highest growth rate; the growth rate of emission from service industry will be higher than that of emission from industry, and the emission from service industry will exceed that from industry after 2010. China can implement emission reduction policy of non-CO2 greenhouse gases to ease the international pressure of CO2 emission reduction. Although the high carbon tax collected can reduce considerable non-CO2 emission, there is little difference in policy efficiency between high carbon tax and low carbon tax. So, in the implementation of emission reduction carbon tax policy of non-CO2 gases, it is necessary to control the carbon tax at a low level.

Progress on Monitoring Methods of Atmospheric Greenhouse Gases

There are many types of methods for monitoring atmospheric greenhouse gases,and the differences between the methods have introduced many uncertainties for the accurate monitoring of atmospheric greenhouse gases.In this paper,the monitoring methods of 7 long-lived greenhouse gases(LLGHG),including carbon dioxide(CO_(2)),methane(CH_(4)),nitrous oxide(N_(2)O),hydrofluorocarbons(HFCs),perfluorocarbons(PFCs),sulfur hexafluoride(SF_(6))and nitrogen trifluoride(NF_(3)),which are regulated and controlled in the Kyoto Protocol and the Doha Amendment,were summarized,and the principle,characteristics and application research progress of each method were systematically studied.Besides,their application scope was analyzed,and the domestication research of relevant instruments was analyzed and prospected.At present,the monitoring methods of atmospheric greenhouse gases are developing towards automation and multi-component simultaneous rapid detection,and are accelerating its integration with new technologies such as big data and satellite remote sensing monitoring;top-down and bottom-up methods are used to provide strong data support for carbon peaking and carbon neutral management decisions in various countries.

Variations in Column Concentration of Greenhouse Gases in China and Their Response to the 2015-2016 El Niño Event

Since the industrial revolution,enhancement of atmospheric greenhouse gas concentrations as a result of human activities has been the primary cause of global warming.The monitoring and evaluation of greenhouse gases are significant prerequisites for carbon emission control.Using monthly data of global atmospheric carbon dioxide(CO_(2))and methane(CH4)column concentrations(hereinafter XCO_(2) and XCH_(4),respectively)retrieved by the Greenhouse Gas Observation Satellite(GOSAT),we analyzed the variations in XCO_(2)and XCH_(4)in China during 2010-2022 after confirming the reliability of the data.Then,the influence of a strong El Niño event in 2015-2016 on XCO_(2) and XCH_(4) variations in China was further studied.The results show that the retrieved XCO_(2) and XCH_(4) from GOSAT have similar temporal variation trends and significant correlations with the ground observation and emission inventory data of an atmospheric background station,which could be used to assess the variations in XCO_(2) and XCH_(4) in China.XCO_(2) is high in spring and winter while XCH_(4) is high in autumn.Both XCO_(2) and XCH_(4) gradually declined from Southeast China to Northwest and Northeast China,with variation ranges of 401-406 and 1.81-1.88 ppmv,respectively;and the high value areas are located in the middle-lower Yangtze River basin.XCO_(2) and XCH_(4) in China increased as a whole during 2010-2022,with rapid enhancement and high levels of XCO_(2) and XCH_(4) in several areas.The significant increases in XCO_(2) and XCH_(4) over China in 2016 might be closely related to the strong El Niño-Southern Oscillation(ENSO)event during 2015-2016.Under a global warming background in 2015,XCO_(2) and XCH_(4) increased by 0.768%and 0.657%in 2016 in China.Data analysis reveals that both the XCO_(2) and XCH_(4) variations might reflect the significant impact of the ENSO event on glacier melting in the Tibetan Plateau.

中国农业源非CO_(2)温室气体排放核算

中国作为传统的农业大国,高消耗、高投入、高需求的农业发展模式推动着中国农业非CO_(2)温室气体排放总量持续增长。农业源非CO_(2)气体以极具增温潜势的CH_(4)和N2O为主,控制农业源非CO_(2)温室气体排放是我国实现农业绿色发展和“双碳”目标的重要环节。我国农业系统非CO_(2)温室气体核算尚处于不断探索完善的过程之中,在估算方法、模型参数等方面还未形成一套完整和公认的体系。研究参考IPCC分类法建立了适用于中国农业系统的,包括种植业、畜牧业和农业废弃物的农业非CO_(2)温室气体排放核算体系。以2020年为基准对中国农业温室气体排放情况进行了核算。结果显示,我国农业系统非CO_(2)温室气体排放总量为62801.68万t CO_(2)-e,CH_(4)是农业系统排放贡献最大的温室气体。我国农业系统温室气体排放类型具有明显的空间分异特征;西北、华北、西南以畜牧业温室气体为主导,华东、华南地区以种植业为主导,东北、华中地区较为特殊,主导类型相对复杂;农业废弃物排放主要分布在东北、华东地区。研究所构建的温室气体核算体系可充分体现我国农业温室气体排放现状,体现各省域农业温室气体排放结构,有利于各区域制定有针对性的农业规划政策,可为降低我国农业温室气体核算研究中的不确定性、为碳中和实现过程中明确农业系统的温室气体贡献提供方法支持与数据基础。

Decoupling CO2 from Climate Change

This study determines if there is a correlation between rising carbon dioxide levels and global warming. Historical data were reviewed from three different time periods spanning 500 million years. It showed that the curves and trends were too dissimilar to establish a connection. Observations from CO2/temp ratios showed that the CO2 and the temperature moved in opposite directions 42% of the time. Many ratios displayed zero or near zero values, reflecting a lack of response. As much as 87% of the ratios revealed negative or near zero values, which strongly negate a correlation. The infrared spectra showed the Greenhouse Gases had an exceptionally low absorption band between 11.67 μm to 9.1 μm, which is a zone called the infrared atmospheric window. Most of the Greenhouse Gases absorb little infrared inside that zone. And that zone is where the Earth’s surface emits almost all infrared radiation. Even with minimal absorbance, water vapor captures the most infrared radiation. It absorbs 84 times more than CO2, 407 thousand times more than methane, 452 thousand times more than ozone and 2.3 million times more than nitrous oxide. The Intergovernmental Panel on Climate Change (IPCC) and the United States EPA excluded water vapor because it was not associated with man-made activities. They reported that water vapor and clouds were simply feedback mechanisms from CO2. Clouds reflect radiation from the sun. The Northern Hemisphere is 2.7°F warmer than the Southern Hemisphere because of clouds. The world cloud cover has gone down 4.1% from 1982 to 2018. Calculations show that this could be responsible for 2.4°F of the 2.7°F. The research shows that most of the recent increase in temperature (89.9%) is because of fewer clouds.

2009-2019年黑龙江龙凤山区域大气本底站CO_(2)浓度变化特征

利用2009—2019年黑龙江龙凤山区域大气本底站CO_(2)浓度长期监测数据,分析了中国东北区域大气本底站CO_(2)浓度的日变化、月变化以及年际变化趋势,探讨了影响龙凤山区域大气本底站CO_(2)浓度的气象驱动因子。结果表明:龙凤山大气本底站CO_(2)浓度日变化表现为在夏季变化幅度最大,其次是秋季,春季次之,冬季变化幅度最小,每日峰值出现在08:00之前,16:00左右出现最低值。CO_(2)浓度月变化表现为最大值出现在1月,平均值约为416.1×10^(-6),最小值出现在7月,平均值为391.1×10^(-6)。CO_(2)浓度季节变化表现为冬季CO_(2)浓度明显高于其他季节,平均值为415.4×10^(-6),夏季出现最低值,其平均值为395.8×10^(-6)。研究期内龙凤山区域大气本底站CO_(2)平均浓度呈现增长趋势,增长率为2.45×10^(-6)/a。龙凤山区域大气本底站春季最大频率风向出现在SSW方向(21.0%),夏季最大频率风向出现在SSW和S方向(23.1%和22.7%),秋季最大频率风向出现在SSW方向(23.4%),冬季风向频率最大值出现在SW方向(31.6%),不同季节CO_(2)浓度高值均出现在北风主导条件下。龙凤山区域大气本底站CO_(2)浓度与温度呈负相关(-0.54),相对湿度与CO_(2)浓度在春季和秋季呈显著负相关(-0.44和-0.55),CO_(2)浓度与风速相关性较小,可能与较高浓度CO_(2)源输送有关。

施氮和增温对鄱阳湖灰化薹草(Carex cinerascens Kukenth.)湿地秋草生长期氧化亚氮排放的影响

湿地是地球上十分重要的氮库,而且对大气氮沉降增加、气候变暖等全球变化响应非常敏感。目前关于湿地氧化亚氮(N_(2)O)的研究还存在较大的区域不均衡性,湿地N_(2)O排放对全球变化的响应也具有很大的不确定性。因此,本研究通过在鄱阳湖灰化薹草(Carex cinerascens Kukenth.)湿地开展N_(2)O通量原位监测及全球变化模拟实验,以揭示鄱阳湖灰化薹草湿地N_(2)O排放变化特征及其对施氮和增温的响应关系。结果表明,鄱阳湖灰化薹草湿地总体上是N_(2)O弱源,平均N_(2)O通量为(5.77±1.45)μg/(m^(2)·h)。施氮对鄱阳湖灰化薹草湿地N_(2)O通量有显著影响,相对于不施氮,施氮可显著提升2.7倍的N_(2)O排放通量。增温及其与施氮的交互作用对N_(2)O通量的影响不显著。鄱阳湖灰化薹草湿地N_(2)O排放过程主要由湿地植物调节,而与空气温度、土壤温度、土壤水分等非生物因素无显著相关关系。研究结果有利于深入认识全球变化与湖泊湿地N_(2)O排放的互馈作用,并为评估全球变化背景下湖泊湿地N_(2)O收支平衡提供重要支撑;未来还需要加强多因子交互作用研究并开展长期连续监测,从而为阐明湿地氮循环对全球变化的响应机制和构建气候预测模型提供验证数据和理论依据。

北京城市大气CO_2浓度变化特征及影响因素

北京大气CO2 浓度日变化强烈 ,全年北京时间 1 5 :0 0时前后为全天最低值 ,最高值则出现在夜间 ,日变化幅度为 2 3 2～ 3 9 0 μmol·mol- 1,夏季和秋季日变化幅度比冬季和春季大 .北京城区大气CO2 浓度季节变化明显 ,最大值出现在冬季 ,月平均浓度为 42 1 5～ 441 0 μmol·mol- 1;最小值则在夏季 ,月平均浓度 3 67 4～ 3 71 6μmol·mol- 1.北京CO2 浓度的季节变化幅度明显高于附近的华北兴隆区域站和瓦里关山大陆本底站等的相应值 ,其原因是北京CO2 浓度季节变化主要受人为取暖活动控制 ,同时植被的季节变化也起一定作用 .1 993～ 1 995年北京大气CO2 浓度上升较快 ,平均增长率为 3 7%·a- 1,1 995年平均浓度达到最高 ,为 40 9 7± 2 5 9μmol·mol- 1。

填闲作物对烤烟生长和温室气体排放的影响

为了解填闲作物对烤烟生长和温室气体排放的影响,本研究以潮土烟田为研究对象,在冬季休闲期分别种植光叶紫花苕(Vicia villosa var.glabrescens)、小黑麦(×Triticale Wittmack)和油菜(Brassica napus),地上部分饲用,残茬还田,分析各处理间填闲作物及烤烟生物学产量、土壤CO_(2)和N_(2)O排放的差异。结果表明:(1)3种填闲作物处理烤烟总生物量和烟叶产量均显著高于对照,其中光叶紫花苕最高、油菜次之;(2)光叶紫花苕-烤烟、小黑麦-烤烟和油菜-烤烟土壤CO_(2)排放量分别略高于、显著高于和显著低于对照,土壤N_(2)O排放量均显著低于对照,其中油菜-烤烟差异最大;(3)烟田土壤CO_(2)的全球增温潜势远大于N_(2)O,光叶紫花苕、小黑麦和油菜处理土壤的全球增温潜势分别是对照的106.1%、116.2%和78.1%。综上所述,黄淮烟区潮土烟田油菜-烤烟种植模式既能提高烤烟收益又可降低烟田土壤的全球增温潜势,光叶紫花苕-烤烟在不显著提高烟田土壤全球增温潜势的同时可更大幅度提高烤烟收益,因此,可因地制宜发展油菜-烤烟或光叶紫花苕-烤烟等种植模式。

金融科技水平影响企业非CO_(2)温室气体排放的实证研究

针对企业非CO_(2)温室气体排放,以2011—2019年中国内地203个地级市面板数据为样本,构建面板门限回归模型,分析企业金融科技发展水平与非CO_(2)温室气体之间的关系.本文验证了金融科技水平影响企业非CO_(2)温室气体排放的结构特征及区域异质性影响.本研究的主要发现包括三个方面:1)金融科技的发展呈现出显著的污染减排效果,能够抑制非CO_(2)温室气体排放.企业的金融科技较低时,其工业二氧化硫减排作用较强,但更一般的情况是,在企业的金融科技水平较高时企业的工业氮氧化物减排效果大多呈现好转的态势.2)企业金融科技发展水平对企业污染减排的作用存在结构效应.金融科技覆盖广度对企业非CO_(2)温室气体的减排强度显著强于金融科技使用深度和金融数字化程度.3)金融科技对非CO_(2)温室气体减排作用存在区域差异,整体来看,中部地区显著高于东西部地区.研究结果对于各地实行差异化金融科技发展策略,推动社会经济发展全面绿色转型,实现“双碳”目标具有一定的指导价值.

江汉平原秸秆还田配合氮肥减施对稻田CH_(4)和N_(2)O排放的影响

为研究江汉平原秸秆还田配合氮肥减施对稻田温室气体排放的影响,设置常规施肥(N)、油菜秸秆加常规施肥(S+N)、油菜秸秆加减氮20%施肥(S+N 80%)3种模式,采用静态暗箱气相色谱法监测稻田CH_(4)与N_(2)O排放速率和累积排放量,结果表明不同施肥处理CH_(4)排放总量范围为69.69~166.97kg/hm^(2),S+N处理较N处理CH_(4)累计排放量增加50.26%,S+N 80%处理较N处理减排CH_(4)达37.28%,以S+N 80%处理减排效果最好;各施肥处理N_(2)O累积排放量为0.49~0.72kg/hm^(2),S+N处理较N处理N_(2)O减排达27.28%,S+N 80%处理较N处理减排N_(2)O达31.94%,以S+N 80%处理减排效果最佳。此外,CH_(4)与N_(2)O之间存在极显著负相关(P<0.01),与NH_(4)^(+)-N存在极显著正相关(P<0.01),与土温存在极显著正相关(P<0.01),N_(2)O与土温存在极显著负相关(P<0.01)。进一步计算100a尺度下CH_(4)和N_(2)O的全球增温潜势(GWP)和温室气体排放强度(GHGI)可知,S+N处理较N处理GWP增加了44.75%,S+N 80%处理相较于N处理GWP减少了36.92%;S+N处理较N处理GHGI上升了32%,S+N 80%处理较N处理GHGI下降了36%,3种施肥模式对产量均无显著影响。由此可知,S+N 80%处理是一种值得推广的施肥方式。

二氧化碳的捕集与矿化利用研究进展

随着全球气候变化日益严峻,有效降低大气中的CO_(2)浓度已成为全球关注的焦点。本文梳理了目前主流的CO_(2)捕集技术,包括液体基CO_(2)捕集、固体基CO_(2)捕集、膜基分离等方法,并详细分析了其优缺点;深入探讨了矿化利用技术,其主要原理是将捕集的CO_(2)转化为稳定的碳酸盐矿物,从而实现碳的永久封存。矿化技术不仅能有效减少温室气体排放,还能为建筑材料等行业提供新的原料来源。随着科学技术的不断进步,CO_(2)的捕集与矿化技术将在应对全球气候变暖中发挥重要作用。

农牧交错带草地生态系统N_(2)O通量对短期氮、磷添加的响应

氮(N)、磷(P)是维持陆地生态系统生产力的重要营养元素,为探求磷添加和氮、磷的交互作用如何影响农牧交错带草地生态系统N_(2)O通量及调控机制,本研究设置对照(CK)、氮添加(N:缓释尿素10 g·m^(-2)·a^(-1))、磷添加(P:磷酸二氢钙10 g·m^(-2)·a^(-1))以及氮、磷同时添加(NP)4个处理,通过静态暗箱-气相色谱法测定2018和2019年生长季N_(2)O通量,通过结构方程模型等寻求氮、磷及其互作效应对N_(2)O通量的影响。结果表明:氮添加显著降低了2018年生长季N_(2)O排放,而磷添加显著降低了两年生长季N_(2)O排放;氮、磷同时添加削弱了单独氮或磷添加对N_(2)O排放的抑制作用;硝态氮、铵态氮和土壤含水量是N_(2)O通量的主要影响因素。因此,氮、磷添加对农牧交错带草地N_(2)O通量的影响存在显著的交互作用,并且受年际间温度和降水的调控,农牧交错带草地养分管理对N_(2)O通量的影响应考虑降水格局的变化。

秸秆还田下大气CO_(2)浓度升高对水稻生长和CH4排放的影响

【目的】明确秸秆还田下大气CO_(2)浓度升高对水稻生长和稻田CH_(4)排放的影响,为气候变化下温室气体排放评估和丰产低碳的稻作技术创新提供理论参考和科学依据。【方法】利用开顶式气室(Open top chamber,OTC)进行田间试验,设置两个CO_(2)浓度处理,分别为正常大气CO_(2)浓度处理(简称aCO_(2),CO_(2)浓度约为0.04%)和大气CO_(2)浓度升高处理(简称eCO_(2),CO_(2)浓度约为0.055%),每个处理的田块混入等量的前茬小麦秸秆,探明秸秆还田下大气CO_(2)浓度升高对水稻产量等生长特性、稻田CH_(4)排放及微生物丰度的影响,揭示秸秆还田下大气CO_(2)浓度升高对CH_(4)排放的影响机制。【结果】大气CO_(2)浓度升高显著促进水稻的生长,使剑叶叶面积增加25.0%,地上生物量增加22.0%,产量提高29.0%。大气CO_(2)浓度升高显著增加了穗数、结实率和千粒重,但对穗粒数影响不显著。秸秆还田下,大气CO_(2)浓度升高有降低稻田CH_(4)排放的趋势,使单位产量CH_(4)排放量降低了39.4%。大气CO_(2)浓度升高使土壤甲烷氧化关键基因pmoA的拷贝数增加了20.0%,但对甲烷产生关键基因mcrA的拷贝数影响较小。【结论】秸秆还田条件下,未来大气CO_(2)浓度升高不仅提高了水稻产量,而且有利于减少稻田温室气体CH_(4)的排放。

Investigation of CO2 solubility in monoethanolamine hydrochloride based deep eutectic solvents and physical properties measurements

Deep eutectic solvents(DESs)have drawn a growing research interest for applications in a wide range of scientific and industrial arenas.However,a limited effort has been reported in the area of gas separation processes and particularly the carbon dioxide capture.This study introduces a novel set of DESs that were prepared by complexing ethylenediamine(EDA),monoethanolamine(MEA),tetraethylenepentamine(TEPA),triethylenetetramine(TETA)and diethylenetriamine(DETA)as hydrogen bond donors to monoethanolamide hydrochloride(EAHC)salt as a hydrogen bond acceptor.The absorption capacity of CO2 was evaluated by exploiting a method based on measuring the pressure drop during the absorption process.The solubility of different DESs was studied at a temperature of 313.15 K and initial pressure of 0.8 MPa.The DES systems 1 EAHC:9 DETA,1 EAHC:9 TETA and 1 EAHC:9 TEPA achieved the highest CO2 solubility of 0.6611,0.6572 and 0.7017 mol CO2·(mole DES)-1 respectively.The results showed that CO2 solubility in the DESs increased with increasing the molar ratio of hydrogen bond donor.In addition,the CO2 solubility increased as the number of amine groups in the solvent increases,therefore,increasing the alkyl chain length in the DESs,resulted in increasing the CO2 solubility.FTIR analysis confirms the DES synthesis since no new functional group was identified.The FTIR spectra also revealed the carbamate formation in DES-CO2 mixtures.In addition,the densities and viscosities of the synthesized DESs were also measured.The CO2 initial investigation of reported DESs shows that these can be potential alternative for conventional solvents in CO2 capture processes.

CO_2,CH_4 and N_2O flux changes in degraded grassland soil of Inner Mongolia,China

The main purpose of this study was to explore the dynamic changes of greenhouse gas（GHG）from grasslands under different degradation levels during the growing seasons of Inner Mongolia, China.Grassland degradation is associated with the dynamics of GHG fluxes, e.g., CO2, CH4 and N2O fluxes. As one of the global ecological environmental problems, grassland degradation has changed the vegetation productivity as well as the accumulation and decomposition rates of soil organic matter and thus will influence the carbon and nitrogen cycles of ecosystems, which will affect the GHG fluxes between grassland ecosystems and the atmosphere. Therefore, it is necessary to explore how the exchanges of CO2,CH4 and N2O fluxes between soil and atmosphere are influenced by the grassland degradation. We measured the fluxes of CO2, CH4 and N2O in lightly degraded, moderately degraded and severely degraded grasslands in Inner Mongolia of China during the growing seasons from July to September in 2013 and 2014. The typical semi-arid grassland of Inner Mongolia plays a role as the source of atmospheric CO2 and N2O and the sink for CH4. Compared with CO2 fluxes, N2O and CH4 fluxes were relatively low. The exchange of CO2, N2O and CH4 fluxes between the grassland soil and the atmosphere may exclusively depend on the net exchange rate of CO2 in semi-arid grasslands. The greenhouse gases showed a clear seasonal pattern, with the CO2 fluxes of –33.63–386.36 mg/（m·h）, CH4 uptake fluxes of 0.113–0.023 mg/（m·h） and N2O fluxes of –1.68–19.90 μg/（m·h）. Grassland degradation significantly influenced CH4 uptake but had no significant influence on CO2 and N2O emissions. Soil moisture and temperature were positively correlated with CO2 emissions but had no significant effect on N2O fluxes.Soil moisture may be the primary driving factor for CH4 uptake. The research results can be in help to better understand the impact of grassland degradation on the ecological environment.

基于生物固碳技术的CO_(2)资源化利用研究进展

温室气体CO_(2)积累而导致的全球性气候变化引起了人们的广泛重视,目前全球已有超过120个国家和地区提出了碳中和目标。生物固碳技术因具有反应条件温和、产品多样性等优点,使其在CO_(2)资源化利用方面表现出优异的应用前景。分别对光合作用固碳原理和微生物电化学固碳原理进行了阐述,主要介绍了光合作用固碳资源化利用方式,如微藻固碳制甲烷、微藻固碳制生物燃料、微藻处理废水等,以及其他生物固碳及资源化利用方式,并对未来基于生物固碳技术的CO_(2)资源化利用技术的重点研究方向进行了展望。

2016—2020年常州市温室气体浓度及相关因素分析

基于2016—2020年常州市主要温室气体的监测数据,采用长时间序列分析和相关性分析等方法,研究了二氧化碳(CO_(2))和甲烷(CH_(4))浓度的变化趋势,分析了CO_(2)和CH_(4)与污染物和气象要素的相关性,初步探讨了生物源和人为源的影响。结果表明:常州市大气CO_(2)和CH_(4)年平均浓度分别为416.4 ppm和1635.7 ppb,上升速率均高于青海瓦里关全球大气本底站同期水平。CO_(2)和CH_(4)浓度整体表现为夏季低、冬季高的季节变化,CO_(2)浓度在8月和12月分别达到最小和最大值,CH_(4)浓度7月和10月分别达到最小和最大值。夏季光合作用、植物生长等生物源对CO_(2)和CH_(4)浓度影响较大,冬季人类活动、工业生产等影响增加。CO_(2)浓度日变化呈现为早晚高、午后低的双峰结构,春季受光合作用影响有更明显的日变化规律。CH_(4)浓度表现单峰的日变化特征,秋季CH_(4)浓度最高,且日变化最明显,表明秋季生物源对CH_(4)影响更明显。CO_(2)和CH_(4)与NO_(2)、NOx、PM_(2.5)和PM_(10)均有较强的正相关性,两者与NO_(2)和NOx相关性最强,表明受机动车影响较大;与气象参数的相关性则明显减弱,在风速增大时,扩散条件有利于CO_(2)和CH_(4)浓度降低。

极端降水条件下土壤中O_(2)浓度对CO_(2)和N_(2)O浓度变化的调控作用

在干旱和半干旱区,降水是农田土壤温室气体排放的重要驱动因素,但极端降水条件下温室气体(CO_(2)、N_(2)O)浓度、排放特征及其与土壤O_(2)动态变化的关系尚不清楚。针对3种土壤管理措施(不施肥、施氮肥、秸秆还田),模拟极端降水(单次100 mm)条件下,高频率监测3种管理措施土壤O_(2)、CO_(2)和N_(2)O浓度及其地表CO_(2)、N_(2)O通量。与对照(单次10 mm)相比,极端降水条件下不施肥、施氮肥、秸秆还田3种处理N_(2)O累积排放量分别增加310%、440%和190%;CO_(2)累积排放量分别增加27%、1%和−11%;地表CO_(2)、N_(2)O通量与土壤CO_(2)、N_(2)O浓度动态变化基本一致,并存在显著正相关关系(P<0.05)。极端降水后土壤中O_(2)浓度呈现先降低后升高的趋势,而CO_(2)、N_(2)O浓度变化则呈相反趋势;土壤中CO_(2)、N_(2)O浓度与O_(2)浓度均呈显著负相关关系(P<0.05);但随着O_(2)浓度的降低,CO_(2)呈生长曲线型增长,而N_(2)O呈指数型增长。极端降水条件下土壤中O_(2)、CO_(2)和N_(2)O浓度变化达到峰值的时间较早。极端降水在促进土壤O_(2)浓度消耗的同时,也促进了土壤温室气体的产生与排放。本研究结果为明确雨养区农田土壤温室气体的排放机制提供了理论支撑。

Effect of Substitution Degree and the Calcination Temperature on the N₂O Decomposition over Zinc Cobaltite Catalysts

In this paper, a series of zinc cobaltite catalysts with the general formula Znx-Co1-xCo2O4 (x = 0.25, 0.50, 0.75 and 1.0) has been prepared using the co-precipitation method. Thermal analyzes (TGA and DTA) were used to follow up the thermal events accompanying the heat treatment of the parent mixture. Based on these results, the various parent mixtures were calcined at 500℃. The obtained solid catalysts were characterized by using XRD, FT-IR and N2-adsorption. The catalytic decomposition of N2O to N2 and O2 was carried out on the zinc-cobaltite catalysts. It was found that partial replacement of Co2+ by Zn2+ in Co3O4 spinel oxide led to a significant improvement in their N2O decomposition activity. Moreover, the catalytic activity was found to be depended on the calcination temperature utilized.