Impact of microorganism degradation on hydrocarbon generation of source rocks: A case study of the Bozhong Sag,Bohai Bay Basin

The discovery of the Bozhong 19-6 gas field, the largest integrated condensate gas field in the eastern China in 2018, opened up a new field for the natural gas exploration deep strata in the Bohai Bay Basin, demonstrating there is a great potential for natural gas exploration in oil-type basins. The ethane isotope of the Bozhong 19-6 condensate gas is heavy, showing the characteristics of partial humic gas. In this paper, aimed at the source rocks of the Bozhong 19-6 gas field in the Bohai Bay Basin, the characteristics of the source rocks in the Bozhong 19-6 structural belt were clarified and the reason are explained from impact of microorganism degradation on hydrocarbon generation of source rocks why the condensate oil and gas had heavy carbon isotope and why it showed partial humic characteristics was explored based on the research of parent materials. The following conclusions were obtained: The paleontology of the Bozhong 19-6 structural belt and its surrounding sub-sags is dominated by higher plants, such as angiosperm and gymnosperm. During the formation of source rocks, under the intensive transformation of microorganism, the original sedimentary organic matter such as higher plants was degraded and transformed by defunctionalization. Especially, the transformation of anaerobic microorganisms on source rocks causes the degradation and defunctionalization of a large number of humic products such as higher plants and the increase of hydrogen content. The degradation and transformation of microorganism don’t transform the terrestrial humic organic matter into newly formed “sapropel” hydrocarbons, the source rocks are mixed partial humic source rocks. As a result, hydrogen content incrased and the quality of source rocks was improved, forming the partial humic source rocks dominated by humic amorphous bodies. The partial humic source rocks are the main source rocks in the Bozhong 19-6 gas field, and it is also the internal reason why the isotope of natural gas is heavy.     

零漂改正对中国地壳运动观测网络重力数据处理的影响

基于中国地壳运动观测网络2000年流动重力观测数据,分析18台LCR-G型相对重力仪的零漂特性。结果显示,重力仪零漂率在某些时段变化较大,最大达10 μGal/h以上。根据重力仪零漂改正的不同处理方法,利用传统平差模型与改进模型对观测数据进行平差计算,并对结果进行比较。在相同先验中误差的情况下,传统平差模型的后验中误差为39 μGal,重力值平均精度为26.5 μGal,而改进模型的后验中误差为16.5 μGal,重力值平均精度为11.2 μGal,远高于传统平差模型。在数据预处理阶段按闭合观测分段进行零漂改正,可以有效消除重力仪零漂剧烈变化的影响,明显优于将仪器零漂率当作固定参数的计算方法。     

Temporal and spatial variations of global solar radiation over the Qinghai–Tibetan Plateau during the past 40 years

Global solar radiation is of great significance to the balance of ground surface radiation, the energy exchange between the Earth’s surface and atmosphere, and the development of weather and climate systems in various regions. In this study, the monthly global radiation recorded at 23 stations over the Qinghai–Tibetan Plateau (QTP) was utilized to estimate global solar radiation (Q) from sunshine duration and to obtain improved fits to the variation coefficients of the monthly Angström–Prescott model (APM). The modeling results were evaluated by calculating the statistical errors, including mean bias error, mean absolute error, root mean square error, and mean relative error. We demonstrate that the monthly Q values can be predicted accurately by APM over the QTP. We also assess the variations of Q values at 116 meteorological stations by APM over the QTP during 1961–2000. The analysis shows that the annual mean sunshine duration amounted to more than 3,000 h over the whole plateau, implying promising prospects for economic applications of solar energy. During the past 40 years, the mean global solar radiation has been relatively high in the western QTP, extending northward to the Inner Mongolian Plateau. Although its decadal variations in the QTP and surrounding regions were inconsistent, the anomaly values of global solar radiation were generally positive during the 1960s and 1970s, indicating that the QTP’s global solar radiation has increased during those periods. The anomaly values were negative during the 1980s and 1990s, showing that the plateau’s global solar radiation has decreased during those periods. Global solar radiation over the QTP is negatively proportional to latitude but positively proportional to altitude and relative sunshine duration. Three factors, the sunshine duration, latitude, and altitude, exert great influence on global surface radiation, of which sunshine duration is most significant. A high-variation-coefficient zone of global solar radiation occurred in the western part of the QTP but, on average, the variation coefficient of the plateau’s global solar radiation was only 0.031, suggesting that the variation in global radiation was relatively stable over the whole QTP.     

极地气象与全球变化

目前，全球变化加快，极地地区变化尤为突出，这对区域或全球的社会、经济和生态系统都将产生显著的影响。最明显的证据是极区的冰川和冰雪范围持续减少，永久冻土在消融和消失，北冰洋海冰范围和厚度减小。极地环境的变化跟地球其它区域的变化息息相关，如臭氧洞的形成与来自低纬度的污染物积聚有关。极地地区的科学研究非常重要，不断地给我们提出新的科学挑战。极地冰盖下和大面积海冰下存在着大量的未知领域，许多极地研究的前沿问题实际上存在于传统学科的交叉领域。因此，世界气象组织（WMO）和国际科联（ICSU）共同发起并于2007年3月1日启动实施2007-2008年国际极地年（IPY），旨在为极地气象学、海洋学、冰川和水文学等领域的科学研究和观测做出贡献，有助于发展更精确的海一冰一大气环流模式，进一步提高对天气预报和气候变化的预测和预估水平。     

内蒙古农牧交错带草地生产力对气候要素的响应——以多伦县为例

利用内蒙古农牧交错带多伦县50余a的气候资料,基于Miami和Thornthwaite Memorial气候模型,分析了该地区草地生产潜力对气候要素的响应。结果表明,Thomthwaite Memorial模型更能反映草地生产潜力随气候要素的变化规律。温度升高和降水增加均对当地草地生产潜力起正作用。其中,相对温度而言,降水对草地生产潜力的限制作用更为明显。另外,利用多伦县1999～2002年的畜牧业统计资料,对天然草地和人工草地的有效生产潜力和实际产量作了对比,其中天然草地的草地生产潜力开发度很低,仅为26％,具有很大的开发空间。人工草地的实际产量和草地生产潜力开发度相对更高,显示了它作为提高该地区牧草产量有效途径的可能性。最后通过对比多伦县2000～2002年的理论和实际载畜量,提出该地区草原处于高超载状态,平均超载率高达79．3％。     

无锡市霾天气特征及影响因子研究

利用太湖北岸无锡气象局国家基本气象观测站1980—2011年地面气象观测资料及1991—2011年无锡市统计年鉴资料,对无锡市霾天气演变特征、气象要素特征及其影响因素进行了分析。结果表明：无锡市的霾日数总体呈上升趋势,近5年来更加明显;霾日数冬季>春季>秋季>夏季;连续10 d及以上霾过程都经历了地面均压场、〖JP2〗入海高压后部及地面倒槽3个连续天气过程。出现重度霾的地面天气形势为地面均压场型、冷锋前型、地面低压倒槽型3种类型。连续10 d以上的霾及重度霾,中低空气团的后向轨迹都出现了下沉运动,且气团经过地区为污染物浓度较高区域。工业污染物中的粉尘排放是造成20世纪90年代霾日数增加的最大因素,2004年以后由于工业废气的排放量以及汽车拥有量的逐年增加,霾日数仍然呈上升趋势。     

Climate Sensitivity and Feedbacks of a New Coupled Model CAMS-CSM to Idealized CO_2 Forcing: A Comparison with CMIP5 Models

Climate sensitivity and feedbacks are basic and important metrics to a climate system. They determine how large surface air temperature will increase under CO_2 forcing ultimately, which is essential for carbon reduction policies to achieve a specific warming target. In this study, these metrics are analyzed in a climate system model newly developed by the Chinese Academy of Meteorological Sciences(CAMS-CSM) and compared with multi-model results from the Coupled Model Comparison Project phase 5(CMIP5). Based on two idealized CO_2 forcing scenarios, i.e.,abruptly quadrupled CO_2 and CO_2 increasing 1% per year, the equilibrium climate sensitivity(ECS) and transient climate response(TCR) in CAMS-CSM are estimated to be about 2.27 and 1.88 K, respectively. The ECS is near the lower bound of CMIP5 models whereas the TCR is closer to the multi-model ensemble mean(MME) of CMIP5 due to compensation of a relatively low ocean heat uptake(OHU) efficiency. The low ECS is caused by an unusually negative climate feedback in CAMS-CSM, which is attributed to cloud shortwave feedback(λSWCL) over the tropical Indo-Pacific Ocean.The CMIP5 ensemble shows that more negative λSWCL is related to larger increase in low-level(925–700 hPa)cloud over the tropical Indo-Pacific under warming, which can explain about 90% of λSWCL in CAMS-CSM. Static stability of planetary boundary layer in the pre-industrial simulation is a critical factor controlling the low-cloud response and λSWCL across the CMIP5 models and CAMS-CSM. Evidently, weak stability in CAMS-CSM favors lowcloud formation under warming due to increased low-level convergence and relative humidity, with the help of enhanced evaporation from the warming tropical Pacific. Consequently, cloud liquid water increases, amplifying cloud albedo, and eventually contributing to the unusually negative λSWCL and low ECS in CAMS-CSM. Moreover, the OHU may influence climate feedbacks and then the ECS by modulating regional sea surface temperature responses.     

柴达木盆地南缘石炭系Chondrites遗迹化石的发现及其地质意义

在柴达木盆地南缘野外地质调查过程中,在祁曼塔格山前石拐子剖面下石炭统石拐子组和乌图美仁庆华铁矿附近剖面的上石炭统缔敖苏组中发现了大量Chondrites遗迹化石。经鉴定,研究区的Chondrites遗迹化石主要包括Chondrites fenxiangensis Yang,1984（分乡丛藻迹）;Chondrites filifalx Volk,1964（细枝丛藻迹）和Chondrites maqianensis Yang,1988（玛沁丛藻迹）3个遗迹种。根据研究区的Chondrites遗迹化石特征,结合岩性特征和其他实体化石资料,认为石拐子地区早石炭世为台洼沉积环境,乌图美仁庆华铁矿地区晚石炭世为局限碳酸盐岩台地沉积环境。另外,探讨了生物扰动对两个地区储集层的改造作用。该研究对恢复柴达木盆地南缘的沉积环境和古生态以及评价研究区的储集层物性具有重要的借鉴意义。     

湖泊湿地水文过程研究进展

湖泊湿地是世界上最重要的生态系统之一,在调蓄洪水、净化环境、保护生物多样性以及为人类提供淡水和食物等方面发挥着不可替代的作用.然而,受气候变化和人类活动叠加影响,湖泊湿地水文过程发生了剧烈变化,湖泊湿地面临着面积萎缩、质量下降和服务功能退化等风险.本文总结了原位观测、数值模拟和遥感技术在获取湖泊湿地关键水文要素方面的优...