莺歌海盆地东方区天然气成藏模式及优质天然气勘探策略

莺歌海盆地东方区天然气勘探取得重大突破,本文对该区不同气田、不同层段的72个天然气样品,开展了化学组分及其稳定碳同位素分析。研究表明该区天然气存在迥然不同的分布差异：西南区块（XY1-1S/XY13-2构造）,浅层天然气中CO2含量高,天然气成熟度总体也较高,而中深层天然气中CO2含量很低,天然气成熟度也相对较低;东北区块（XY1-1/XY13-1构造）,浅层天然气中CO2含量总体较低,天然气成熟度也较低,但是中深层天然气中CO2含量总体较高,天然气成熟度也相对较高。根据天然气系列地化特征,结合底辟活动的分析,提出东方区受底辟影响的低能量区和高能量区具有截然不同的天然气充注成藏模式：①西南区块（XY1-1S/XY13-2构造）远离底辟核心区,属低能量活动的底辟波及区,受底辟活动影响程度相对较小,早期低CO2含量、低成熟天然气沿小断裂或裂隙输导体系运移到中深层的黄流组、梅山组聚集成藏。由于底辟能量较低,中深层早期形成的气藏得以完整保存。后期,烃源岩生成的高CO2含量、高成熟天然气沿着底辟活动产生的断层向上运移至莺歌海组浅层聚集成藏。浅层和中深层天然气输导体系可能存在一定差异;②东北区块（XY1-1/XY13-1构造）处于底辟核心区,属高能量活动区,多期强烈的底辟活动形成深大断裂,为天然气的快速运移提供通道,使得早期在黄流组、梅山组中深层聚集的低CO2含量、低成熟天然气遭受破坏,向上发生再次运移至浅层莺歌海组聚集成藏。后期高CO2含量、高成熟天然气主要充注中深层。该模式可以很好地解释莺歌海盆地东方区天然气复杂的分布特征,为莺歌海盆地不同领域,尤其是中深层高温超压领域低CO2的优质天然气勘探提供策略指导。     

地表CO2浓度分布模拟试验及分析

如何获取CO₂浓度时空分布特征,是气候变化研究中的一个关键问题。本文基于中国碳卫星在吉林航飞试验区的地面观测数据,分析地表CO₂浓度与环境变量的相关关系,运用多元线性回归与HASM高精度曲面建模相结合的方法,模拟航飞区地表CO₂浓度分布格局。结果表明：CO₂浓度空间分布受气象条件的影响较大,短波辐射是影响CO₂浓度的重要因素;第1时段整体浓度最高,特别是在西部区域;第2时段CO₂浓度高值区东移,呈现西低东高的分布特点;第3时段浓度空间分布与第2时段有类似的特征,但细节存在差异,且高值区缩小;精度对比显示在采样点较少及采样密度不大的情况下,HASM方法的模拟误差小于Kriging方法。因此,这种使用多元线性回归模型通过引入环境变量获得高分辨率趋势面,结合HASM模型进行修正残差提高模拟结果精度的手段,可作为模拟地表CO₂浓度时空分布的有效方法。     

戈壁地区夏季碳和水热循环及其湍流特征

本文利用2006年夏季大气边界层观测资料,采用涡动相关法分析了我国西北地区戈壁下垫面碳收支及水热循环的规律和特征,并分析了大气湍流特征.结果表明:夏季白天的CO₂湍流通量呈逆输送特征,即CO₂白天向下输送,夜间向上输送,平均数值为-0.199 mg·m^-2·s^-1,整体上表现为碳汇;戈壁地区湿度小,其数值受水平来流的影响较大,日变化特征不明显;温度的归一化标准差与稳定度参数的关系满足Monin-Obukhov Similarity (MOS)理论;温度和CO₂的能谱相似;互谱uc与uθ,wc与wθ相似;水汽和CO₂的输送主要受水平方向湍流的影响.     

巢湖水体二氧化碳浓度时空分布特征及其水-气交换通量

为揭示巢湖水体二氧化碳浓度（cCO₂）时空变化特征及其影响因素,2017年2、4、8和11月分别采集巢湖表层水样,测定水样的理化、生物学参数以及cCO₂,并以此计算其水-气界面交换通量.结果表明：巢湖表层水体cCO₂的变化范围为13.31~55.47 μmol/L,年平均值为26.27 μmol/L,在空间上呈现出西高东低的分布趋势;在季节上表现为暖季（夏季）低、冷季（春、秋和冬季）高的规律.巢湖表层水体cCO₂与溶解性有机碳浓度呈显著正相关,与叶绿素a浓度呈显著负相关,说明有机质分解和光合作用在巢湖CO₂生物化学循环过程中占重要作用;同时,南淝河等入湖河流污染严重,输入大量有机和无机碳,对西巢湖水体CO₂贡献较大.总体上,巢湖CO₂排放量相对较低,巢湖部分区域在冷季（2、11月）表现为CO₂的汇.本研究对于明晰富营养化湖泊CO₂排放特征以及准确估算全球内陆湖泊碳通量等都具有参考价值.     

夏季降雨事件对水库温室气体通量变化的影响:来自湖北官庄水库的高频观测

湖库淡水水域对温室气体排放的贡献不容小觑,然而观测时间的代表性不足以及缺乏对降雨因素的考虑制约了碳排放的准确估计.本研究以湖北宜昌境内官庄水库为例,选取强降雨多发的夏季时段,针对水气界面温室气体通量、水体表层和垂向剖面气体溶存浓度及环境因子开展了为期1周的原位高频观测,以探讨夏季降雨事件对水库温室气体通量变化的影响.结果表明,观测期内官庄水库水气界面CH₄通量变化范围为0.007~0.077 mg/（m²·h）,CO₂通量范围为5.48~57.57 mg/（m²·h）,白天和夜晚均表现为大气的碳源.小雨、中雨乃至暴雨天气条件下,CH₄和CO₂日均通量均较低,日通量倾向于受风速和温度调控.CH₄和CO₂通量变化趋势较为一致,观测期内日间排放量高于夜间排放量出现的次数更多,昼夜差异对降雨天气状况无明显响应,风速是CH₄和CO₂通量昼夜变化的主导因素.暴雨过程中,CH₄-k₆₀₀和CO₂-k₆₀₀与水气温差存在显著正相关,但水体垂向混合过程十分短暂.在平均雨强为3.8 mm/h的暴雨第I阶段,CH₄-k₆₀₀对风速和降雨的响应明显,而在雨强更大（8.5 mm/h）的第II阶段,CH₄-k₆₀₀与风速、降雨均未表现出相关性,通量箱在强降雨条件下的适用性可能存在雨强阈值.     

Convergence of per capita carbon dioxide emissions: implications and meta-analysis

There is a rich empirical literature testing whether per capita carbon dioxide emissions tend to converge over time and across countries. This article provides a meta-analysis of the results from this research, and discusses how carbon emissions convergence may be understood in, for instance, the presence of international knowledge spillovers and policy convergence. The results display evidence of either divergence or persistent gaps at the global level, but convergence of per capita carbon dioxide emissions between richer industrialized countries. However, the results appear sensitive to the choice of data sample and choice of convergence concept, e.g. stochastic convergence versus β-convergence. Moreover, peer-reviewed studies have a higher likelihood of reporting convergence in carbon dioxide emissions compared to non-refereed work.

POLICY RELEVANCE

The empirical basis for an egalitarian rule of equal emissions per capita in the design of global climate agreements is not solid; this supports the need to move beyond single allocation rules, and increase knowledge about the impacts of combined scenarios. However, even in the context of the 2015 Paris Agreement with its emphasis on voluntary contributions and ‘national circumstances’, different equity-based principles could serve as useful points of reference for how the remaining carbon budget should be allocated.     

Transformation of Aerosol Chemical Properties due to Transport Over a City

The change of the chemical composition of the near-ground level atmospheric aerosol was studied during two summer episodes by a Lagrangian type of experimental approach. Bulk and single-particle chemical analyses of ions and elements in the particulate phase were deployed. N(-III) and N(V) components were also measured in the gas-phase. The measurements were completed by particle size distributions.Secondary inorganic aerosols (SIA) and fine particles of ≈0.2–0.4 μm size were still elevated 50 km downwind of the city. The direct comparison of transport over the city in contrast to transport over the surrounding areas showed that SIA was formed from emission from the city within less than 3 h. Relative increases, i.e., enrichment during transport were observed for primary and secondary aerosol components. The degree of mixing on the individual particle level increased significantly during transport in the area. In particular, newly emitted carbonaceous particles became internally mixed within hours with pre-existing sulphate particles. Mostly due to secondary aerosol formation the average particle size (mass median diameter) of major constituents of the aerosol was significantly decreased while being transported over 13 h. Given recent insights which link fine particles number and mass concentrations with health risks, the results suggest that rural populations in areas which frequently are located within an urban plume might run an elevated health risk relative to populations in areas not affected by urban plumes.     

气候变化对我国小麦地理分布的潜在影响

根据GCM模拟结果，分析了CO2增加对我国小麦生产地理分布的潜在影响。结果表明:在加倍CO2气候下，我国小麦生产区将进一步向北和向西扩展，小麦栽培特点和品种类型也有较大变化。气候增暖可能对东北地区产生有利影响，但在中部和南部则可能产生高温应力。小麦生长期间平均温度的升高，特别是收获前的高温可能会增加对更早熟、更耐热品种的需求。     

Correction Of Eddy-Covariance Measurements Incorporating Both Advective Effects And Density Fluxes

Equations are presented to correct eddy-covariancemeasurements for both fluctuations in density andnon-zero mean advection, induced by convergence ordivergence of flow, and spatial source/sinkinhomogeneity, under steady-state and transientconditions. This correction collapses to theWebb–Pearman–Leuning expression ifthe mean vertical velocity is zero, and formally addsthe Webb–Pearman–Leuning expression to the correctionssuggested by Lee for conditions ofnon-zero vertical velocity and source/sink and meanscalar horizontal homogeneity. The equation requiresmeasurement of the mean vertical gradients of thescalar concentration of interest (air temperature,humidity, CO₂) as well as an accurateestimation of the mean vertical velocity, in additionto the vertical eddy covariance of the scalar. Simplemethods for the approximation of sensor tilt andcomplex terrain flow angle are presented, to allowestimation of non-zero mean vertical velocities. Theequations are applied to data from a maize crop and aforest to give examples of when the correction issignificant. In addition, a term for thethermodynamic expansion energy associated with watervapour flux is derived, which implies that the sonictemperature derived sensible heat flux will accuratelyinclude this contribution.     

Interannual variation of atmospheric CO2 concentration

A method is described for the analysis of the interannual variability of background atmospheric carbon dioxide concentration. The analysis is carried out on the data from 6 observatories for which records of >8 years were available.A global-scale interannual variation of CO₂ concentration in the troposphere with a characteristic time-scale of 2–3 years has been confirmed throughout the period of the records. These variations are estimated to be associated with carbon cycle imbalances of 2–3 Gt or annual net exchanges between the atmosphere and another carbon reservoir(s) at a rate of about 1.2 Gt of carbon per year. Lag correlations and amplitude comparisons between the records suggests a low latitude southern hemisphere origin to this phenomenon.The interannual variations of CO₂ increase are found to be correlated with those observed in data for Pacific sea surface temperatures and Pacific witd stress, the Southern Oscillation Index and the Quasi-Biennial Oscillation. However multiple regression studies found that once the Southern Oscillation index is used as an explanatory variable for CO₂ variations, the inclusion of additional geophysical variables does not give any significant improvement in the regression.