注入CO2提高煤层气产能的可行性研究

根据煤储层吸附一解吸机理,首次采用“解吸一注气一解吸”的实验方法,分别进行CH4,CO2的吸附一解吸和CO2注入置换煤层CH4实验,模拟了煤层气井“排采一注气一排采”的增产途径和效果。结果表明：在CH4和CO2二元体系的竞争吸附中,CO2组分的吸附速率是先快后慢,而CH4组分的吸附速率先慢后快,解吸时则相反,反映出CO2在竞争吸附中占据优势;注入CO2气体的数量越大和相对浓度越高,单位压降CH4解吸率和CO2吸附率就越高。实验结论对工业规模的煤层气开发试验具有指导意义。     

全球变化中的北极碳汇：现状与未来

由于海冰覆盖，北极碳汇（Arctic Carbon Sink）在全球碳通量预算中经常被忽略或简单处理。但随着全球变化加剧，北极发生快速变化，北极碳循环及其对全球变化的响应与反馈日趋重要。综合对北极碳汇的研究结果，分析了北极碳汇的来源、变化以及主要调控因子，评估了北极碳汇现状。探讨了在全球变化中，影响北极碳汇变化的因素及其对未来北极碳汇变化趋势的影响。      

1994-2006年长江三角洲和东北平原酸性气体浓度变化

 利用长江三角洲和东北平原地区大气本底站的二氧化硫（SO2）和氮氧化物（NOx）历史资料和近期取得的观测数据,探讨两个地区人为排放对这些气候相关酸性气体的不同贡献。从两种酸性气体过去和现在的浓度水平,估算了它们在两个地区的增长率,比较了NOx与SO2比值的不同变化趋势。结果表明,早在20世纪90年代中期,长江三角洲酸性气体污染水平已经较高,其后主要是NOx浓度显著升高,从而使该地区成为硫和氮污染并重的地区;东北平原酸性气体过去浓度很低,但这些气体以很高的速率增长,虽然目前浓度水平仍然比较低,但未来形势不容乐观。     

气态SO_2转化及其数值模型研究

本文基于对室外烟雾箱实验,探讨了SO_2的转化机制及影响SO_2转化的因素,由此并借助于烟团模型,建立了SO_2转化和硫酸盐气溶胶细粒子生成的数值模型,用于估算从排放源排入大气的SO_2浓度及其转化成硫酸盐细粒子的浓度以及它们的空间分布,与实测结果相比,两者有较好的一致性.同时指出,由于大气中细粒子(粒径小于1μm)可通过人体呼吸进入并沉积在肺泡中而对健康有不利影响,从而说明研究大气中细粒子污染的迫切性.     

The effect of gas-phase chemistry on aqueous-phase sulfur dioxide oxidation rates

The rates and mechanisms of both gas and liquid phase reactions for the oxidation of sulfur dioxide play an important role in the production of atmospheric acids and aerosol particles. Rhodeet al. (1981) concluded that sulfate production rates were highly non-linear functions of sulfur dioxide emission rates. Their modelling study used an HO _x termination mechanism for the HO—SO₂ reaction in the gas-phase. Stockwell and Calvert (1983) determined that one of the products of the overall reaction of HO with sulfur dioxide was an HO₂ radical. The National Research Council (1983) using a version of the Rhodeet al. (1981) model modified to include HO₂ production from the HO—SO₂ reaction concluded that sulfate production becomes much more linear with respect to reductions in sulfur dioxide emissions. However, the cause of this increased linearity was not explained by the National Research Council report. It is demonstrated that the increased linearity is due to the coupling of gas-phases and aqueous phase chemistry. The gas-phase sulfur dioxide oxidation mechanism has a very significant effect on hydrogen perodide production rates.     

Covariations in oceanic dimethyl sulfide,its oxidation products and rain acidity at Amsterdam Island in the Southern Indian Ocean

Simultaneous measurements of rain acidity and dimethyl sulfide (DMS) at the ocean surface and in the atmosphere were performed at Amsterdam Island over a 4 year period. During the last 2 years, measurements of sulfur dioxide (SO₂) in the atmosphere and of methane sulfonic acid (MSA) and non-sea-salt-sulfate (nss-SO₄ ^2-) in rainwater were also performed. Covariations are observed between the oceanic and atmospheric DMS concentrations, atmospheric SO₂ concentrations, wet deposition of MSA, nss-SO₄ ^2-, and rain acidity. A comparable summer to winter ratio of DMS and SO₂ in the atmosphere and MSA in precipitation were also observed. From the chemical composition of precipitation we estimate that DMS oxidation products contribute approximately 40% of the rain acidity. If we consider the acidity in excess, then DMS oxidation products contribute about 55%.     

RESPONSES OF A GLOBAL CGCM TO CO_2 INCREASE

The responses of the climate system to increase of atmospheric carbon dioxide(CO_2)arestudied by using a new version of the Bureau of Meteorological Research Centre(BMRC)globalcoupled general circulation model(CGCM).Two simulations are run:one with atmospheric CO_2concentration held constant at 330 ppm,the other with a tripling of atmospheric CO_2(990 ppm).Results from the 41-year control coupled integration are applied to analyze the mean state,seasonal cycle and interannual variability in the model.Comparisons between the greenhouseexperiment and the control experiment then provide estimations of the influence of increased CO_2on climate changes and climate variability.Especially discussed is the question on whether theclimate changes concerned with CO_2 inerease will impact interannual variability in tropical Pacific,such as ENSO.     

Characteristics of Lake Breezes and Their Impacts on Energy and Carbon Fluxes in Mountainous Areas

In mountainous lake areas, lake–land and mountain–valley breezes interact with each other, leading to an "extended lake breeze". These extended lake breezes can regulate and control energy and carbon cycles at different scales. Based on meteorological and turbulent fluxes data from an eddy covariance observation site at Erhai Lake in the Dali Basin,southwest China, characteristics of daytime and nighttime extended lake breezes and their impacts on energy and carbon dioxide exchange in 2015 are investigated. Lake breezes dominate during the daytime while, due to different prevailing circulations at night, there are two types of nighttime breezes. The mountain breeze from the Cangshan Mountain range leads to N1 type nighttime breeze events. When a cyclonic circulation forms and maintains in the southern part of Erhai Lake at night, its northern branch contributes to the formation of N2 type nighttime breeze events. The prevailing wind directions for daytime, N1, and N2 breeze events are southeast, west, and southeast, respectively. Daytime breeze events are more intense than N1 events and weaker than N2 events. During daytime breeze events, the lake breeze decreases the sensible heat flux(Hs) and carbon dioxide flux(F_{CO_2}) and increases the latent heat flux(LE). During N1 breeze events, the mountain breeze decreases Hs and LE and increases F_{CO_2}. For N2 breeze events, the southeast wind from the lake surface increases Hs and LE and decreases suppress carbon dioxide exchange.     

Variability of NO2 in different environments at a moderately polluted island over the southwestern Indian Ocean

This work presents the temporal evolution and spatial distribution of nitrogen dioxide (NO₂) measured with the help of passive diffusion tubes in different environments: rural, sub-urban, urban, at La Réunion Island in December 1997 and November 2000 (austral spring), respectively. NO₂ concentration exhibits notable enhancement from 1997 to 2000. For instance, its mean concentration was 16 and 20 μg/m³ in December 1997 and November 2000, respectively, at La Réunion Island, especially in inhabited regions due to increase of local anthropogenic activities, mainly traffic circulation, in the absence of house heating and biomass burning. We also observe a net increase of pollutant levels by a factor two in rural/remote areas within 3 years, which is tied to the extension of inhabited areas and air-flows from enhanced local sources. The increase of atmospheric pollutants is mainly due to enhancement of anthropogenic activities (traffic) since the 1990s at La Réunion Island, which results from a constant increase of population and consequently, from a higher number of vehicles in circulation. Importantly, in cities like Saint-Denis, where traffic network has been subject to notable improvement (e.g. single to double lanes, etc.), pollutant levels exhibit little variability as in temperate continental latitudes. Semi-continuous NO₂ concentration measured in parallel with ozone in November 2000 also showed that daytime photochemical ozone production is influenced by pollutant and precursor (NO₂) levels at Saint-Denis, while nighttime ozone increase is mainly tied to dynamical processes. The November 2000 ozone diurnal pattern is notably different from that observed in September 1995, during which a daytime ozone loss was observed, pointing out that atmospheric conditions have been subject to notable changes, i.e., clean to moderately polluted, within a few years at La Réunion Island. The results presented here point out that the ‘source enhancement effect’ is superimposed on dynamical and photochemical processes to influence pollutants variability and hence atmospheric chemistry, in a quite ‘pristine’ tropical oceanic region.     

兰州市冬季SO2大气环境容量研究

通过数值模拟方法,研究了兰州市冬季SO2的大气环境容量,为大气污染的总量控制方法提供了前提和依据。本文利用RAMs三维非流体静力大气动力模式模拟的气象场驱动中尺度大气扩散模式(HYPACT),模拟出SO2的浓度分布及每个污染单元对于地面浓度的分担率。根据SO2的国家环境空气质量标准(下称质量标准),用线性规划的原理和方法计算了兰州市冬季典型日条件下SO2的大气环境容量。