基于GOSAT卫星的中国CO2浓度时空特征分析

采用温室气体观测卫星(GOSAT) 傅里叶变换光谱仪(FTS)发布的CO₂柱浓度L₃级别数据集产品,利用TCCON地基站点的CO₂柱浓度数据对卫星遥感数据进行验证,分析中国CO₂柱浓度时空变化特征及其影响因素。研究结果表明,GOSAT卫星的CO₂柱浓度产品精度较高,线性回归的r²为0.99,线性方程斜率为0.98,平均偏差为0.11 mg/L。中国CO₂柱浓度呈现逐年增长的趋势,存在12个月的周期性季节性变化。2010、2020年区域年平均CO₂柱浓度分别约为389.30、412.62 mg/L,增长了23.32 mg/L,年平均增长率大约为0.58%。中国区域大气CO₂柱浓度的月变化存在明显的时空差异,最大值和最小值分别出现在4月和8月,2020年4月和8月的区域平均值分别为415.09、409.13 mg/L。中国区域CO₂柱浓度从东部沿海向西部逐级递减,且呈现明显的季节性变化,夏季高值主要集中在东南部沿海地区,冬季高值主要集中在华北地区。     

南京温室气体监测点位规划方法研究

以南京市为温室气体监测区域，以2021年1月和7月作为冬、夏季的代表，利用拉格朗日粒子扩散模型（LPDM）和K均值（K-Means）聚类算法对南京市已有的高塔点位进行筛选，研究温室气体监测点位布设最优位置。通过计算不同点位的城市CO₂贡献度，最终确定了冬季和夏季各8个温室气体监测建议点位。结果表明，通过聚类算法筛选出的监测站点选址能对南京市大部分城区的温室气体排放具有相对最大的覆盖范围和较高的敏感性，能够有效反映出南京市CO₂排放量的梯度变化，对南京市不同时空尺度上的温室气体排放达到相对最好的监测效果。     

北京市废弃物处理温室气体排放特征

基于《2006年IPCC国家温室气体清单指南》推荐的方法，结合《省级温室气体清单编制指南（试行）》和《城市温室气体核算工具指南》的部分数据与核算范围，针对固体废弃物填埋、焚烧和废水处理等过程，核算了北京市2005-2014年废弃物处理过程中温室气体总排放量。结果表明：2005-2014年北京市废弃物处理过程温室气体总排放量呈逐渐上升趋势，2014年温室气体总排放量比2005年增长98%。10年间，固体废弃物填埋过程一直是最主要的温室气体排放源，到2014年排放量达到最大，为416.3×10⁴t二氧化碳当量（CO₂e）。废弃物填埋、废水处理和废弃物焚烧过程占总排放量的比例分别为78.5%（CO₂e质量分数，下同）、13.5%和8%。结合已有研究，系统优化国内7个典型城市废弃物处理温室气体排放因子，核算7个城市排放情况，并对比分析了北京市排放情况。     

2种环境空气中甲烷自动监测方法的比对分析

光腔衰荡光谱法(CRDS)和气相色谱法（GC）均被广泛应用于环境空气中甲烷（CH₄）的测定。采用CRDS和GC这2种自动监测方法对CH₄标准气体和环境空气样品进行分析比对。结果表明，通过使用统一的标准气体和校准方法，2种方法测定CH₄标准气体的不确定度均＜0.5%，CRDS法的不确定度更低；2种方法测定CH₄环境空气样品结果的平均相对误差为0.28%，Z检验法显示，2种方法没有显著性差异，并具有很高的相关性和一致性。提出，对于测量精度和稳定性更高的大气CH₄监测领域，建议优先选用CRDS法或经过比对达到同等性能的方法；而对于测量精度和稳定性要求稍低的CH₄排放源及周边等监测领域，可以采用GC法。     

适用于城市碳排放反演的CO2格点化排放清单编制——以杭州市为例

基于碳监测网络测算城市人为碳排放通量，需要二氧化碳（CO₂）格点化排放清单作为反演计算的先验信息。现有格点化清单大多针对全球或全国尺度编制，排放源的空间位置不确定性高，不足以支撑城市碳监测工作。以杭州市为例，构建了高空间分辨率（1 km）、分部门（工业能源、工业过程、交通等6类排放部门）的城市CO₂格点化排放清单，并对其不确定性进行了表征。该格点化清单基于中国城市温室气体工作组编制的《中国城市二氧化碳排放数据集（2020）》，依据848个点源的精确位置信息和一系列空间代理数据，对各部门的城市CO₂排放量进行格点化分配，得到杭州市高分辨率排放清单模型。与现有清单，如欧洲开发的全球大气研究排放数据库（EDGAR）、清华大学开发的中国多尺度排放清单模型（MEIC）等相比，本研究编制的格点化清单能合理地反映杭州市CO₂排放的空间格局，包括人口、路网密集的市中心，萧山区和钱塘区的工业园区，钱塘江中上游沿岸的水泥企业等高排放热点，可以作为杭州市CO₂反演的人为源先验清单。     

基于CiteSpace的温室气体监测发展动态可视化分析

采用文献计量方法，利用CiteSpace软件对Web of Science核心合集中2004—2020年以"Greenhouse Gases Monitoring"为主题词检索到的2 514篇文献进行可视化分析，从时间分布、国际合作、研究机构合作、研究领域、共被引分析和关键词分析等方面，揭示该领域的发展动态、研究实力分布、热点前沿等。结果表明：2004—2020年温室气体监测研究领域的发文数量总体呈现上升趋势，在全球应对气候变化的重大事件时间节点发文数量增幅较大；该领域发文量较多的国家和机构皆以发达国家为主，发展中国家中中国居首位，国家、机构合作关系紧密；温室气体监测研究涉及的学科领域较广，环境科学与生态学、环境科学、工程为排名前3位的学科领域，2010年后研究逐步拓展到建筑学、影像学、计算机科学、经济学等领域；该领域的研究知识基础主要聚焦温室气体浓度监测、来源去向、影响因素及变化趋势分析，温室气体监测技术方法研究及应用，以及森林、农业土壤碳汇研究等方面；通过不同时段关键词分析发现CO₂、CH₄和N₂O一直是温室气体监测研究的重点对象，关注视角逐渐转向多因素、多领域、多技术、多方法、多策略研究。基于分析结果和中国实际，提出今后一段时期中国温室气体监测领域的研究重点和工作方向。     

大气14CO2的加速器质谱分析技术研究进展

利用加速器质谱技术测定大气¹⁴CO₂以示踪大气化石源CO₂成为当前减污降碳工作的热点。该文从加速器质谱¹⁴C分析基础出发,系统介绍了加速器质谱的工作原理、大气样品的采集及纯化、石墨化样品的制备和测定,阐述了大气碳监测领域14 CO₂测试的研究进展。随着加速器质谱技术的不断发展,大气¹⁴CO₂的研究将会更加广泛和深入,有助于进一步认识大气化石源CO₂的来源,更有针对性地开展减污降碳工作。未来应统一制定¹⁴CO₂监测方法标准,规范操作流程和质控手段,完善实验仪器配套设施,加快提升监测能力和水平。     

北京大气中异戊二烯的季变化、日变化形式及影响因素研究

对2005年北京大气中异戊二烯进行了一年的观测分析。结果表明,异戊二烯体积分数年平均值为0.58×10^-9,月平均值为0.1×10^-9～1.8×10^-9,7月最高,1月最低。春、秋、冬三季,异戊二烯日变化形式呈三峰形,分别在14:00、18:00、02:00;18:00、02:00、08:00;02:00、10:00、16:00出现峰值;夏季异戊二烯体积分数日变化呈现白天高夜晚低且在14:00出现峰值。夏季异戊二烯源排放主要由生物排放控制,其日变化形式受温度、辐射影响大;春季和秋季异戊二烯源排放受汽车尾气和生物排放共同控制,其日变化形式受汽车尾气影响大,温度、辐射也有一定影响;冬季异戊二烯源排放主要由汽车尾气控制,其日变化形式主要受汽车尾气影响。不同季节北京大气中的异戊二烯体积分数日变化形式与PM_2.5浓度日变化形式大致相同。     

2022年青岛市沿海区域臭氧污染特征及传输影响分析

基于2022年1—12月青岛市沿海区域臭氧（O₃）自动监测数据和气象观测资料，对O₃污染变化特征及影响因素进行了分析，结合后向轨迹聚类与潜在源区分析等方法，对O₃外来输送通道及潜在源分布情况进行分析研究。结果表明：青岛市沿海区域O₃污染主要集中在4—10月份，日变化特征呈单峰单谷趋势，峰值出现在15：00—16：00；气象因素中，地面短波辐射对O₃浓度变化的相对贡献最大，偏南风易导致O₃污染；受二氧化氮（NO₂）滴定作用以及海陆风转换影响，沿海区域O₃峰值与谷值均滞后青岛城区1 h左右；O₃生成整体处于VOCs控制区，1-丁烯、正丁烷与异戊烷是O₃污染期间导致O₃浓度上升的关键组分；O₃污染的主要潜在源区为长三角北部和黄海近岸海域，以及山东中南部地区。     

基于OCO-2卫星重构的中国地区高覆盖XCO2时空分布特征

卫星遥感技术是深入了解大气二氧化碳（CO₂）时空分布特征的重要手段之一，由于探测技术的限制，目前基于卫星遥感观测数据反演的CO₂产品的空间覆盖度较低，数据缺失严重，不足以反映CO₂浓度的空间分布情况。现基于轨道碳观测卫星-2 （OCO-2）、哨兵5P （Sentinel-5P）、美国CO₂同化模拟系统（Carbon Tracker）和欧洲中期天气预报中心第5代（ERA-5）气象再分析数据，结合时间序列拟合估算模型和随机森林算法，重构了2019—2022年中国地区高精度（0.05°×0.05°）大气CO₂平均干空气混合比（XCO₂），分析了中国地区CO₂时空变化特征。与OCO-2和Carbon Tracker对比结果显示，重构得到的XCO₂与OCO-2的观测结果一致性更高，均方根误差为1.05 ×10^-6，决定系数高达0.96，可以在较高空间分辨率上体现中国地区XCO₂的时空分布情况。基于重构的XCO₂数据得知，中国地区XCO₂呈现明显的季节性波动，XCO₂呈冬春高、夏秋低的特征；2019—2022年，中国地区XCO₂呈现逐年上升的趋势，增长率达到（2.41±0.01）×10^-6/a，但近年来增长速率有所降低；从空间分布来看，中国东部、北部、中部地区的XCO₂显著高于其他地区，且增长率也较高；进一步分析中国典型经济区的XCO₂发现，杭州、天津、成都的XCO₂在各经济区内的增长最为迅速。研究成果可为碳监测研究、碳排放清单验证、碳排放管理、温室气体减排等研究提供重要的数据支撑。     

Empirical gas emission and oxidation measurement at cover soil of dumping site: example from Malaysia

Methane (CH₄) is one of the most relevant greenhouse gases and it has a global warming potential 25 times greater than that of carbon dioxide (CO₂), risking human health and the environment. Microbial CH₄ oxidation in landfill cover soils may constitute a means of controlling CH₄ emissions. The study was intended to quantify CH₄ and CO₂ emissions rates at the Sungai Sedu open dumping landfill during the dry season, characterize their spatial and temporal variations, and measure the CH₄ oxidation associated with the landfill cover soil using a homemade static flux chamber. Concentrations of the gases were analyzed by a Micro-GC CP-4900. Two methods, kriging values and inverse distance weighting (IDW), were found almost identical. The findings of the proposed method show that the ratio of CH₄ to CO₂ emissions was 25.4 %, indicating higher CO₂ emissions than CH₄ emissions. Also, the average CH₄ oxidation in the landfill cover soil was 52.5 %. The CH₄ and CO₂ emissions did not show fixed-pattern temporal variation based on daytime measurements. Statistically, a negative relationship was found between CH₄ emissions and oxidation (R ²?=?0.46). It can be concluded that the variation in the CH₄ oxidation was mainly attributed to the properties of the landfill cover soil.     

华东森林及高山背景区域CO2和CH4浓度变化特征

对国家大气背景监测福建武夷山站2014—2018年的主要温室气体监测数据进行分析,探讨华东森林及高山背景区域大气中CO_2和CH_4浓度的变化特征。结果表明:华东森林及高山区域CO_2背景浓度为414.1×10~(-6)(摩尔分数,下同),5年间呈逐年上升趋势; CH_4背景浓度为1 977×10~(-9),2014—2016年呈逐年上升趋势,2016—2018年保持稳定;两者均具有较明显的季节和月变化特征,CO_2还具有较明显的日变化特征,但季节变化幅度、月平均浓度振幅和日变化幅度均较小,具有区域背景特征。     

A mathematical model to estimate errors associated with closed flux chambers

Errors associated with the closed flux chamber technique, used to measure surface emissions from landfills, were investigated by using a combination of numerical modeling and laboratory studies. A transient-state, advective–dispersive–reactive model was developed and used in conjunction with its steady-state version to quantify the errors associated with closed flux chambers. In developing the model, all four major gases, CH₄, O₂, CO₂, and N₂, and the oxidation of CH₄ to CO₂ were considered. Laboratory experiments were conducted on a monolayered as well as a two-layered landfill cover system to calibrate and verify the model. The model was used to develop a plot of the percentage errors associated with closed flux chambers of different dimensions and surface flux rates.     

Greenhouse gas emissions from forestry,land-use changes,and agriculture in Tanzania

The purpose of the study was to identify and quantify anthropogenic sources and sinks of greenhouse gases from forestry, land-use changes and agriculture in Tanzania. The 1990 inventory revealed that, in the land-use sector, methane (CH₄) and carbon dioxide (CO₂) are the primary gases emitted. Enteric fermentation in livestock production systems is the largest source of CH₄. Although deforestation results in greenhouse gas emissions, the managed forests of Tanzania are a major CO₂ sink.     

Inspection of non-CO2 greenhouse gases from emission sources and in ambient air by Fourier-transform-infrared-spectrometry: Measurements with FTIS-MAPS

Infrared spectrometry is a versatile basis to analyse greenhouse gases in the atmosphere. A multicomponent air pollution software (MAPS) was developed for retrieval of gas concentrations from radiation emission as well as absorption measurements. Concentrations of CO, CH₄, N₂O, and H₂O as well as CO₂, NO, NO₂, NH₃, SO₂, HCl, HCHO, and the temperature of warm gases are determined on-line. The analyses of greenhouse gases in gaseous emission sources and in ambient air are performed by a mobile remote sensing system using the double-pendulum interferometer K300 of the Munich company Kayser-Threde. Passive radiation measurements are performed to retrieve CO, N₂O, and H₂O as well as CO₂, NO, SO₂, and HCl concentrations in smoke stack effluents of thermal power plants and municipal incinerators and CO and H₂O as well as CO₂ and NO in exhausts of aircraft engines. Open-path radiation measurements are used to determine greenhouse gas concentrations at different ambient air conditions and greenhouse gas emission rates of diffusive sources as garbage deposits, open coal mining, stock farming together with additional compounds (e.g. NH₃), and from road traffic together with HCHO. Some results of measurements are shown. A future task is the verification of emission cadastres by these inspection measurements.     

The Kyoto Protocol and non-CO2 Greenhouse Gases and Carbon Sinks

Many trace constituents other than carbon dioxide affect the radiative budget of the atmosphere. The existing international agreement to limit greenhouse gases, the Kyoto Protocol, includes carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF₆) and credit for some carbon sinks. We investigate technological options for reducing emissions of these gases and the economic implications of including other greenhouse gases and sinks in the climate change control policy. We conduct an integreated assessment of costs using the MIT Emissions Prediction and Policy Analysis (EPPA) model combined with estimates of abatement costs for non-CO₂ greenhouse gases and sinks. We find that failure to take advantage of the other gas and sink flexibility would nearly double aggregate Annex B costs. Including all the GHGs and sinks is actually cheaper than if only CO₂ had been included in the Protocol and their inclusion achieves greater overall abatement. There remains considerable uncertainty in these estimates, the magnitude of the savings depends heavily on reference projections of emissions, for example, but these uncertainties do not change the overall conclusion that non-CO₂ GHGs are an important part of a climate control policy.     

CH4 continuous measurements in the upper Spanish plateau

Continuous methane, CH₄, concentrations were measured in a rural area of the upper Spanish plateau from June 2010 to May 2012 by cavity ring-down spectroscopy technique. The results obtained have proven the local impact of anthropogenic nearby sources on CH₄ concentrations, and evidence a significant influence on the overall mean, averaged daily and seasonal patterns recorded at the measuring site. The positive anomalies in CH₄ concentrations, statistically significant at 95 %, in the southeast sector, defined here as ESE, SE, SSE and S sectors, have been attributed to the contribution of the Valladolid urban plume and the urban landfill. Based on this finding, CH₄ background levels were associated to the concentrations recorded in the remaining un-disturbed sectors. CH₄ means of the overall data set, the southeast sector and background sectors yielded average means of 1,894.1, 1,927.9 and 1,887.1 ppb, respectively. The diurnal and seasonal patterns of the overall data set and background concentrations have shown that CH₄ concentrations are mainly dominated by its reaction with OH radicals. Maximum hourly concentrations were reached during night-time and early morning, 5–7 h, whereas minimum concentrations were recorded at 16 h. Maximum and minimum monthly means were recorded in January and July, respectively. The diurnal and seasonal amplitudes, namely, peak-to-peak means, of background concentrations were 25.1 and 48.1 ppb, respectively. These values were significantly lower than those obtained for the overall data set, 42.9 and 58.1 ppb, revealing the significant role of local influences on CH₄ concentrations despite the low frequency of southeast winds recorded at the measuring site, 16.9 %.     

Ground level volume mixing ratio of methane in a tropical coastal city

Urban regions are hotspots of greenhouse gas emissions which include CO₂, CH₄, N₂O, etc. Methane is a strong greenhouse gas which is produced from a number of sources including fossil fuel combustion, municipal waste, and sewage processing, etc. Ground level mixing ratio of methane in the tropical coastal city of Thiruvananthapuram in South India, during calm early morning period was measured. Measurements were done during both winter and summer seasons. Concentrations were significantly higher than global average value. Intra-city variation in ground level mixing ratio was also significant. Ground level methane concentration at Thiruvananthapuram urban area showed maximum value of 3.16 ppmV. Under stable atmospheric conditions in early morning, ground level mixing ratio of methane was 2.79 ppmV in winter and 2.54 ppmV during summer. The spatial distribution of methane concentration shows correlation with urban heat island.     

Inter-seasonal and spatial distribution of ground-level greenhouse gases (CO<Subscript>2</Subscript>, CH<Subscript>4</Subscript>, N<Subscript>2</Subscript>O) over Nagpur in India and their management roadmap

Ground-level concentrations of carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) were monitored over three seasons, i.e., post-monsoon (September–October), winter (January–February), and summer (May–June) for 1 year during 2013–2014 in Nagpur City in India. The selected gases had moderate to high variation both spatially (residential, commercial, traffic intersections, residential cum commercial sites) and temporally (at 7:00, 13:00, 18:00, and 23:00 hours in all three seasons). Concentrations of gases were randomly distributed diurnally over city in all seasons, and there was no specific increasing or decreasing trend with time in a day. Average CO₂ and N₂O concentrations in winter were higher over post-monsoon and summer while CH₄ had highest average concentration in summer. Observed concentrations of CO₂ were predominantly above global average of 400 ppmv while N₂O and CH₄ concentrations frequently dropped down below global average of 327 ppbv and 1.8 ppmv, respectively. Two-tailed Student’s t test indicated that post-monsoon CO₂ concentrations were statistically different from summer but not so from winter, while difference between summer and winter concentrations was statistically significant (P < 0.05). CH₄ concentrations in all seasons were statistically at par to each other. In case of N₂O, concentrations in post-monsoon were statistically different from summer but not so from winter, while difference between summer and winter concentrations was statistically significant (P < 0.05). Average ground-level concentrations of the gases calculated for three seasons together were higher in commercial areas. Environmental management priorities vis a vis greenhouse gas emissions in the city are also discussed.     

Mitigation Strategy to Contain Methane Emission from Rice-Fields

Methane is primarily a biogenic gas, which is implicated in global climate change. Among all the sources of methane emission, paddy fields form the most dominant source. An experiment was conducted with a common paddy crop (Oryza sativa var. Vishnuparag) by amending the soils with different organic manures and biofertilizers with a view to find out an inexpensive strategy to mitigate methane emission from the rice-fields. The results revealed that there was a seasonal change in the CH₄ flux, registering a peak at heading stage in all treatments. The application of rice straw before flooding and the biofertilizer after flooding enhances CH₄ efflux from the rice-fields significantly, while composts of cowdung and leaves did not stimulate CH₄ production and, rather, decreased CH₄ fluxes. As soil pH and temperature were optimum for methanogenesis, it was likely that the organic C and the redox potential mainly modulated methane production and its emission through rice plants.