二氧化碳地质储存的主要环境问题及研究进展

CO2地质储存是缓解温室效应的有效手段之一.在CO2地质储存工程实施过程中可能引起断裂、地震、淡水含水层污染等地质灾害问题,对人类和生态环境造成危害.本文系统阐述CO2地质储存过程中造成的环境地质问题及其成因机制,并从风险评价、监测预警、应急补救等角度提出了具体防治措施,对CO2地质储存技术的安全性评估及工程实施项目管理具有重要的实际意义.     

Sources and flows of embodied CO2 emissions in import and export trade of China

This paper uses the Global Trade Analysis Project(version 7)database to calculate embodied CO2emissions in bilateral trade between China and other countries(regions)based on input-output methods.The sources and flows of embodied CO2emissions in import and export trade of China are analyzed.Results show that the flows of embodied CO2emissions in export trade are highly concentrated.The main flows to the United States(US)and Japan account for 1/4 and 1/7 of the total CO2emissions in export trade,respectively.Concentrated flows of total exports and small differences in export structure are the main reasons for the highly concentrated export trade.The sources of embodied CO2emissions in import trade have relatively low concentration.Taiwan Province of China,Hong Kong Special Administrative Region of China,US,Russia,Republic of Korea,and Japan account for around 7.72%–12.67%of the total embodied CO2emissions in import trade.The relative dispersion of import sources,the impact of the import structure,and the level of production technology in importing countries caused low concentration of CO2emissions in import trade.Overall,the embodied CO2emissions in the export trade of China are higher than those in import trade.As a result,production-based CO2emissions are higher than consumption-based CO2emissions.The difference of 8.96×108t of CO2,which comes mainly from the US,Japan,Germany,and the United Kingdom,accounts for 58.70%of the total difference.Some suggestions,such as improving energy efficiency,alerting high carbon-intensive industries transfer,expanding the market for sharing risks,and prompting the accounting system of consumption-based CO2emissions,are proposed based on the results.     

基于航次观测和再分析资料的南海海表二氧化碳分压反演及变化机制分析*

海表二氧化碳分压(pCO₂)是指海洋表层水和大气之间的二氧化碳(CO₂)交换处于动态平衡时CO₂的含量, 是描述海-气CO₂交换的一个主要因子。本文利用2008—2014年覆盖南海大部分海域的海表pCO₂观测资料, 结合现场海表温度和海表盐度以及卫星观测的叶绿素a数据, 构建了基于多元线性回归方法的分区域反演模型。模型在水深浅于30m的区域均方根误差为5.3μatm, 其余海区均方根误差为10.8μatm, 与前人基于个别航次的有限区域反演结果的均方根误差相当。利用该模型公式和HYbrid Coordinate Ocean Model(HYCOM)再分析海表温、盐数据及MODIS-Aqua卫星观测的叶绿素a数据进行反演, 得到了时空分辨率为5'×5'的2004—2016年的逐月南海海表pCO₂数据。该数据能较好地反映南海海表pCO₂在海表温度影响下, 春夏高、秋冬低的季节变化特征, 与前人基于航次观测的研究结果相似, 表明反演模型具有较高的可信度。进一步分析发现, 南海及邻近海域平均海表pCO₂具有显著的准十年振荡特征: 2012年附近出现了极小值, 之前表现为降低的趋势, 之后略有升高的趋势。受海表pCO₂的影响, 南海海盆平均海-气CO₂通量在2012年之前出现了显著降低的趋势, 表明南海释放到大气中的CO₂减少, 并在2007年之后的冬季出现了负值(从碳源变为碳汇), 2012年之后变化较为平缓。热带太平洋年代际振荡引起的南海区域海表盐度变化是造成海表pCO₂及海-气CO₂通量准十年变化的主要原因。分区分析的结果表明, 南海北部海表pCO₂变化最为显著, 在南海海表pCO₂的季节和准十年变化中都起到非常重要的作用。     

Reply to Comment on ‘Marine GIS: Identification of mesoscale oceanic thermal fronts’

Geographic information service (GIService) has become popular in the last decade to develop applications for addressing global challenges. Performance is one of the most important criteria to help users select distributed online GIService for developing geospatial applications including natural hazards and emergency responses. However, performance accuracy is limited by the single-location-based evaluation mechanism while service performance is dynamic in space and time between end-users and services. We propose a spatiotemporal performance evaluation mechanism to improve the accuracy. Specially, a cloud and volunteer computing mechanism is proposed to collect performance information of globally distributed GIServices. A global spatiotemporal performance model is designed to integrate spatiotemporal dynamics for better performance evaluation for users from different regions at different times. This model is tested to support GIService selection in global spatial data infrastructures (SDIs). The experiment confirms that the proposed model provides more accurate evaluations for global users and better supports geospatial resource utilizations in SDIs than previous mechanisms. The methodology can be adopted to improve the services of other regional and global distributed operational systems.     

重庆雪玉洞CO_2浓度变化的自然与人为因素探讨

通过对重庆雪玉洞洞穴CO2浓度、地下河CO2分压及地下河水、滴水次生沉积物稳定碳同位素δ13C等地球化学指标进行的完整水文年监测,并结合该洞以往的CO2短期观测记录,发现洞内与CO2相关的环境因子均存在显著的季变性,其总体特征是:CO2浓度夏高冬低,δ13C夏轻冬重。对比每月游客量变化,发现人为因素对洞穴CO2环境的改变远弱于自然因素,洞内发育的常年地下河在其中起主导作用。地下河的存在使不同相态的碳在洞内快速流动交换以达到平衡,从而在"质"上(同位素比)和"量"上(浓度)反映外部环境的季节变化,又使得各项地球化学指标在每年的4月和11月换季时呈现突变特征。可推断雪玉洞CO2的改变来源于地下河对洞穴上部土壤CO2的传递,最终归因于土壤层生物活动对季节气候条件变化的响应。而雪玉洞地下河在CO2变化过程中的传递作用十分突出,可作为同类型洞穴的借鉴,为旅游开发服务。     

On the major proposals for carbon emission reduction and some related issues

We evaluated and ran simulations for seven proposals for the reduction of global CO2 emissions (e.g.,those of the Intergovernmental Panel on Climate Change (IPCC),United Nations Development Program,and Organization for Economic Cooperation and Development).All the proposals ignored the fact that the cumulative CO2 emissions per capita for developed countries were 7.54 times those for developing countries in the historical period of 1900-2005.These proposals further deliberately allocate 2006-2050 emission q...     

Stratigraphy of the mid‐ to upper‐Cretaceous System in the Aridagawa area,Wakayama, Southwest Japan

The litho‐ and biostratigraphy of the mid‐ to upper‐Cretaceous System around the Yagumaike Pond in the Aridagawa area, Wakayama, Southwest Japan, were investigated. Many Middle to Late Albian megafossils were found in the strata of a block bounded by faults. It was also revealed that the Upper Cretaceous System of other blocks ranges from the Middle Turonian to Santonian. The Albian megafossil assemblage contains few benthic organisms, in contrast with the abundance of nektons found (e.g. cephalopods). Sedimentological observations of the mudstone profiles also indicate that scarcely or weakly bioturbated, well‐laminated mudstone is dominant among the Albian deposits. These results suggest deposition of the Albian mudstone under a dysaerobic to anoxic environment. It is comparable to the extended oceanic anoxia (OAEs) in mid‐Cretaceous time. Albian deposits with similar characteristics are also known to exist in Shikoku, Southwest Japan. A wide sedimentary basin that was directly affected by global environmental events, such as OAEs, seemed to be formed on the Chichibu Belt in the Albian. The Upper Cretaceous strata in the study area are extremely thin, similar to the coeval deposits on the Chichibu Belt in Shikoku. It is suggested that the sedimentation rate in the sedimentary basin on the Chichibu Belt was extremely low during early Late Cretaceous time.     

基于居民出行行为的北京市交通碳排放影响机理

近年来低碳城市逐渐成为众多学科关注的焦点所在,国内外学者从多个角度对其开展一系列的理论与实证研究,但从微观层面深入探讨城市交通碳排放的影响机理的研究相对较为缺乏。利用北京市居民活动日志调查获取的第一手数据,基于居民日常出行行为计算微观层面的城市交通碳排放,并采用结构方程模型深入挖掘居住空间、个体行为以及交通碳排放三者之间的内在关系。结果表明,出行距离、机动出行概率对交通碳排放产生显著的正效应,而出行频率的影响并不显著;同时,出行结构的影响要远远大于出行总量的影响。另外,城市空间结构对城市交通碳排放产生显著影响,单位社区居民的出行行为整体具有“低碳”性质,应从低碳视角对单位社区进行重新审视。     

盐生荒漠生态系统二氧化碳通量的年内、年际变异特征

采用涡度相关法,并结合小气候观测,对荒漠生态系统净二氧化碳通量进行了连续3个生长季的观测（2004—2006年）,并据此分析了荒漠生态系统净二氧化碳通量及其主要成分GPP和Reco的季节和年际间变化特征。结果表明,在生长季尺度上,各个阶段二氧化碳吸收量的大小分别为:生长旺盛期>生长初期>生长末期,这可能与植物叶面积的大小以及光合有效辐射,大气温度等环境要素有关系。在年际尺度上,3个生长季同阶段的二氧化碳吸收量存在明显差异,生长季初期5月,2004年碳吸收最强,2006年次之,2005年最小。对于生长旺盛期,降水量最大的2004年碳吸收能力最强,正午最大值可以达到-0.12 mg·m-2·s-1,2005年次之,最大值达-0.06 mg·m-2·s-1,仅仅是2004年最大值的1/2,2006年最小,正午吸收的最大值为-0.02 mg·m-2·s-1,生长季末期,3个生长季的月均日变化非常相似,其在正午的最大吸收值也没有显著差异,正午最大吸收量为-0.01 mg·m-2·s-1左右,其他时段均在0值附近。即使在降水量相近的两个年份里（2005—2006年）,其NEE的最大值出现时间也不一致,2005年NEE的最大月累计量出现在8月和9月,而2006年则出现在6月和7月,这可能与年内降水量分布格局有关。3个生长季荒漠生态系统均表现为净二氧化碳吸收,其吸收量分别为:-236.18 g·m-2,-63.07 g·m-2和-91.97 g·m-2。年际差异的形成原因是降水差异造成的一年生草本植物数量变化,不利用降水的建群种应该对此没有贡献。