Demonstrating urban pollution using toxic metals of road dust and roadside soil in Chengdu,southwestern China

As one of the largest economical hubs in southwestern China, Chengdu is witnessing fast urbanization characterized by rapid urban sprawl, population growth, infrastructural construction, and motorization. However, this rapid urbanization may lead to environmental degradation, placing human health at risk. In this study, toxic metals in road dust and roadside soil are used as proxies to illustrate environmental changes of Chengdu. In August 2009, 133 dust and 132 soil samples were collected from the first, second and third ring roads, along which areas have urbanized for different times. By means of a portable X-ray fluorescence analyzer, concentrations of Pb, Zn and Cu in the samples were determined. The results indicate that the concentrations and contamination levels of Pb, Zn and Cu in dust declined significantly from the first to the third ring roads, paralleling the decreasing trends in traffic and building densities from the first to the third ring roads. However, concentrations of the three elements in roadside soil were relatively stable among the roads. These data may suggest that the metals in road dust can be used as proxies to demonstrate environmental degradation during the urbanization of Chengdu, while concentrations of the metals in roadside soil are affected more by natural factors (e.g., background concentrations, precipitation, and distance to road) than by anthropogenic factors (e.g., traffic and building densities). Furthermore, compared to Pb concentrations measured in the 1990s, Pb concentrations in road dust have been reduced most likely owing to the exclusion of leaded petrol since 2000. Similar situations may be found in many other cities that are experiencing fast urbanization.     

污染天气下成都城市热岛环流结构的数值模拟

本文利用中尺度模式WRF V3.9对2016年7月16日成都一次污染天气下的城市热岛环流个例进行了数值模拟,分析了城市热岛环流的三维结构及演变特征.并通过设计减少气溶胶光学厚度的敏感性试验,研究了污染对城市热岛环流的可能影响.结果表明：当地时间17：00城市热岛环流开始形成.随着热岛强度增强,环流增强,城乡边界处的城市风锋不断向城市中心推进.19：00热岛环流结构最显著.21：00环流结构被破坏,仅低层存在微弱的乡村风.在热岛环流结构最显著时刻,近地面风场由郊区向城市辐合,地面以上2.0 km处风场由城市向乡村辐散,辐散中心与辐合中心位置大致对应.此时城市风锋在城市处合并,环流的水平尺度约为城市尺度的2~2.5倍.当气溶胶光学厚度减小后,城市热岛环流尺度和强度以减小为主.特别是在热岛环流最显著时刻,低层乡村风风速减小,城市风锋最大上升速度降低,环流的水平尺度在西、南、北三个方向均减小,且高空回流高度降低.可能的影响机制是,气溶胶光学厚度减小后,净辐射通量增大,城乡地表能量通量差异增大,城市边界层高度升高.但城市边界层高度升高对城市热岛的抑制作用超过了城乡地表能量通量差异增加对城市热岛的增强作用,最终造成城市热岛减弱,环流减弱.

     

Characteristics,genesis and accumulation history of natural gas in Hetianhe gasfield,Tarim Basin,China

Hetianhe gasfield in Bachu region of the Tarim Basin is mainly composed of three reservoir-caprock assembly, namely regional caprock of upper mudstone, middle mudstone and lower mudstone of the Carboniferous and reservoir of Bachu bioclastic limestone, glutenite and the Ordovician carbonate buried hill. Natural gas in Hetianhe gasfield sourced from the Cambrian source rock. It is thought that gases in Ma4 well block in the east of Hetianhe gasfield are mainly crude-oil cracked gases, while those in Ma3 and Ma8 well blocks in the west are the mixture gases of kerogen cracked gases and crude-oil cracked gases. Natural gas is rich in H₂S and accumulated in multiply stages as the result of TSR. The accumulation history is divided into three stages, namely accumulation and breakage in the late Caledonian-early Hercynian, migration and dissipation in the late Hercynian and accumulation in Himalayan. The main accumulation of reformed gas reservoir is in Himalayan.     

Characteristics,genesis and accumulation history of natural gas in Hetianhe gasfield,Tarim Basin,China

Hetianhe gasfield in Bachu region of the Tarim Basin is mainly composed of three reservoir-caprock assembly, namely regional caprock of upper mudstone, middle mudstone and lower mudstone of the Carboniferous and reservoir of Bachu bioclastic limestone, glutenite and the Ordovician carbonate buried hill. Natural gas in Hetianhe gasfield sourced from the Cambrian source rock. It is thought that gases in Ma4 well block in the east of Hetianhe gasfield are mainly crude-oil cracked gases, while those in Ma3 and Ma8 well blocks in the west are the mixture gases of kerogen cracked gases and crude-oil cracked gases. Natural gas is rich in H₂S and accumulated in multiply stages as the result of TSR. The accumulation history is divided into three stages, namely accumulation and breakage in the late Caledonian-early Hercynian, migration and dissipation in the late Hercynian and accumulation in Himalayan. The main accumulation of reformed gas reservoir is in Himalayan.

     

Biogas charging and dissipating process and its accumulation in the Sebei gasfield,Qaidam Basin,China

The Sebei gasfield is the largest biogas accumulation found in China and many reservoirs and seal rocks superposed on a syndepositional anticline in Quaternary. The biogas charging and dissipating process and its distribution have been a research focus for many years. The authors suggest a diffusing and accumulating model for the biogas, as they find that the shallower the gas producer, the more methane in the biogas, and the lighter stable carbon isotope composition of methane. Based on the diffusing model, diffused biogas is quantitatively estimated for each potential sandy reservoir in the gasfield, and the gas charging quantity for the sandy reservoir is also calculated by the diffused gas quantity plus gas reserve in-place. A ratio of diffusing quantity to charging quantity is postulated to describe biogas accumulating state in a sandy reservoir, if the ratio is less than 0.6, the reservoir forms a good gas-pool and high-production layer in the gasfield, which often occurs in the reservoirs deeper than 900 m; if the ratio is greater than 0.6, a few gas accumulated in the reservoir, which frequently exists in the reservoirs shallower than 900 m. Therefore, a biogas accumulation model is built up as lateral direct charging from gas source for the sands deeper than 900 m and indirect charging from lower gas-bearing sands by diffusion at depth shallower than 900 m. With this charging and diffusion quantitative model, the authors conducted re-evaluation on each wildcat in the central area of the Qaidam Basin, and found many commercial biogas layers.

     

Characteristics,genesis and accumulation history of natural gas in Hetianhe gasfield,Tarim Basin,China

Hetianhe gasfield in Bachu region of the Tarim Basin is mainly composed of three reservoir-caprock assembly,namely regional caprock of upper mudstone,middle mudstone and lower mudstone of the Carboniferous and reservoir of Bachu bioclastic limestone,glutenite and the Ordovician carbonate buried hill.Natural gas in Hetianhe gasfield sourced from the Cambrian source rock.It is thought that gases in Ma4 well block in the east of Hetianhe gasfield are mainly crude-oil cracked gases,while those in Ma3 and Ma8 well blocks in the west are the mixture gases of kerogen cracked gases and crude-oil cracked gases.Natural gas is rich in H2S and accumulated in multiply stages as the result of TSR.The accumulation history is divided into three stages,namely accumulation and breakage in the late Caledonian-early Hercynian,migration and dissipation in the late Hercynian and accumulation in Himalayan. The main accumulation of reformed gas reservoir is in Himalayan.     

Biogas charging and dissipating process and its accumulation in the Sebei gasfield,Qaidam Basin,China

The Sebei gasfield is the largest biogas accumulation found in China and many reservoirs and seal rocks superposed on a syndepositional anticline in Quaternary.The biogas charging and dissipating process and its distribution have been a research focus for many years.The authors suggest a diffusing and accumulating model for the biogas,as they find that the shallower the gas producer,the more methane in the biogas,and the lighter stable carbon isotope composition of methane.Based on the diffusing model,diffused biogas is quantitatively estimated for each potential sandy reservoir in the gasfield,and the gas charging quantity for the sandy reservoir is also calculated by the diffused gas quantity plus gas reserve in-place.A ratio of diffusing quantity to charging quantity is postulated to describe biogas accumulating state in a sandy reservoir,if the ratio is less than 0.6,the reservoir forms a good gas-pool and high-production layer in the gasfield,which often occurs in the reservoirs deeper than 900 m;if the ratio is greater than 0.6,a few gas accumulated in the reservoir,which frequently exists in the reservoirs shallower than 900 m.Therefore,a biogas accumulation model is built up as lateral direct charging from gas source for the sands deeper than 900 m and indirect charging from lower gas-bearing sands by diffusion at depth shallower than 900 m.With this charging and diffusion quantitative model,the authors conducted re-evaluation on each wildcat in the central area of the Qaidam Basin,and found many commercial biogas layers.     

Biogas charging and dissipating process and its accumulation in the Sebei gasfield,Qaidam Basin,China

The Sebei gasfield is the largest biogas accumulation found in China and many reservoirs and seal rocks superposed on a syndepositional anticline in Quaternary. The biogas charging and dissipating process and its distribution have been a research focus for many years. The authors suggest a diffusing and accumulating model for the biogas, as they find that the shallower the gas producer, the more methane in the biogas, and the lighter stable carbon isotope composition of methane. Based on the diffusing model, diffused biogas is quantitatively estimated for each potential sandy reservoir in the gasfield, and the gas charging quantity for the sandy reservoir is also calculated by the diffused gas quantity plus gas reserve in-place. A ratio of diffusing quantity to charging quantity is postulated to describe biogas accumulating state in a sandy reservoir, if the ratio is less than 0.6, the reservoir forms a good gas-pool and high-production layer in the gasfield, which often occurs in the reservoirs deeper than 900 m; if the ratio is greater than 0.6, a few gas accumulated in the reservoir, which frequently exists in the reservoirs shallower than 900 m. Therefore, a biogas accumulation model is built up as lateral direct charging from gas source for the sands deeper than 900 m and indirect charging from lower gas-bearing sands by diffusion at depth shallower than 900 m. With this charging and diffusion quantitative model, the authors conducted re-evaluation on each wildcat in the central area of the Qaidam Basin, and found many commercial biogas layers.     

震后废墟中Wi-Fi信号场强传输模型研究

针对震后废墟中无法精确检测出电磁波的传输特性问题,本文提出了一种在震后废墟中Wi-Fi信号场强的检测方法。首先是对Wi-Fi信号场强在组成震后废墟主要介质中的传输特性进行检测推导。然后通过测量在废墟不同距离下场强的大小,即可推导出废墟下电磁波的场强与传输距离的关系,最后得出场强在震后废墟中的传输模型。实验表明,该传输模型的计算结果准确度高,对震后废墟中电磁波传输特性的检测具有重要意义。     

Formation mechanism of in-situ volcanic reservoirs in eastern China:A case study from Xushen gasfield in Songliao Basin

A large number of in-situ volcanic reservoirs have been discovered from the Meso-Cenozoic rift basin group in eastern China.Based on drilling results in combination with geological and geophysical analysis,a case study from the Early Cretaceous Xujiaweizi fault-depression shows that the formation mechanism of in-situ volcanic reservoirs is characterized by"fault-controlled body,body-controlled facies,facies-controlled reservoir,and reservoir-controlled accumulation".In other words,deep faults control the volcanic eruption type,volcanic body,and gas reservoir distribution;the volcanic body determines the spatial distribution of volcanic facies and volcanic gas reservoir size;the volcanic facies control reservoir physical properties and effective thickness of gas formation;the volcanic reservoir properties control gas reservoir type and gas productivity.The result is useful to guiding the discovery of in-situ volcanic gas reservoirs in faulted basins in both theory and practice.     

Geological characteristics of large gas provinces and large gas fields in China

Based on the examination of the global researches on oil and gas provinces and large gas fields and the analysis of the features,attributes and distribution of large gas provinces and gas fields,this paper puts forward three indicators of determining large oil and gas provinces:spatial indicator,reservoir-forming indicator and resource indicator.It classifies the gas accumulated areas and large gas provinces in China and analyzes the controlling factors on the distribution of large gas provinces and large gas fields:the lateral distribution is mainly controlled by high-energy sedimentary facies and constructive diagenetic facies,palaeo-highs and their periclinal zones,deep faults,etc,and the vertical distribution is mainly controlled by unconformities,series of evaporates and deep low-velocity highly-conductive beds,etc.It also reveals the main geological characteristics of large gas provinces and large gas fields in China.Large gas fields in four-type basins have their own characteristics and onland large gas fields are dominantly developed in foreland basins and craton basins;there are three types of gas sources,of which,coal is the main source with high gas generating intensity and varying origins;reservoir rocks of the large gas fields(provinces)are of various types and dominated generally by low-middle permeability and porosity pore-type reservoirs;structural traps and litho-stratigraphic traps coexist in Chinese large gas fields and form dense high abundance and large-area low and middle-abundance large gas fields;most of the large gas fields have late hydrocarbon-generation peaks and reservoir formation,and experienced the process of multiple-stage charging and late finalization; large gas provinces(fields)have good sealing and preservation conditions,and evaporates seals are largely developed in large and extra-large gas fields.This paper intends to shed light on the exploration and development of large gas fields(provinces)through analyzing their geological characteristics.     

Geological characteristics of large gas provinces and large gas fields in China

Based on the examination of the global researches on oil and gas provinces and large gas fields and the analysis of the features, attributes and distribution of large gas provinces and gas fields, this paper puts forward three indicators of determining large oil and gas provinces: spatial indicator, reservoir-forming indicator and resource indicator. It classifies the gas accumulated areas and large gas provinces in China and analyzes the controlling factors on the distribution of large gas provinces and large gas fields: the lateral distribution is mainly controlled by high-energy sedimentary facies and constructive diagenetic facies, palaeo-highs and their periclinal zones, deep faults, etc, and the vertical distribution is mainly controlled by unconformities, series of evaporates and deep low-velocity highly-conductive beds, etc. It also reveals the main geological characteristics of large gas provinces and large gas fields in China. Large gas fields in four-type basins have their own characteristics and onland large gas fields are dominantly developed in foreland basins and craton basins; there are three types of gas sources, of which, coal is the main source with high gas generating intensity and varying origins; reservoir rocks of the large gas fields (provinces) are of various types and dominated generally by low-middle permeability and porosity pore-type reservoirs; structural traps and litho-stratigraphic traps coexist in Chinese large gas fields and form dense high abundance and large-area low and middle-abundance large gas fields; most of the large gas fields have late hydrocarbon-generation peaks and reservoir formation, and experienced the process of multiple-stage charging and late finalization; large gas provinces (fields) have good sealing and preservation conditions, and evaporates seals are largely developed in large and extra-large gas fields. This paper intends to shed light on the exploration and development of large gas fields (provinces) through analyzing their geological characteristics.     

Urbanization,urban land expansion and environmental change in China

China’s economic reforms and unprecedented growth have generated many fascinating issues for scholarly research. An understanding of urbanization and land use change in China is required for appropriate strategies and policies to facilitate future sustainable development. This paper reviews the literature on urbanization, land use and sustainable development in China with a focus on land use change. We argue that land use and environmental research are embedded in the complex economic-geographical processes and multiple trajectories of development and urbanization in China. This paper highlights the important role of space–time modeling in a multi-disciplinary setting in the study of urbanization, land use and sustainable development. It also points out potential areas for future research.     

Atmospheric environmental capacity and urban atmospheric load in mainland China

Daily and annual average atmospheric environmental capacity coefficient(A-value) sequences for mainland China are calculated from hourly data recorded at 378 ground stations over 1975–2014. A-values at different recurrence intervals are calculated by fitting the sequences to Pearson type III distribution curves. Based on these A-values and source-sink balance(reference concentration 100 μg m~(-3)), atmospheric environmental capacities at the recurrence intervals are calculated for all of mainland China and each provincial administrative region. The climate average atmospheric environmental capacity reference value for the entire mainland is 2.169×10~7 t yr~(-1). An urban atmospheric load index is defined for analyses of the impact of population density on the urban atmospheric environment. Analyses suggest that this index is also useful for differentiating whether air quality changes are attributable to varying meteorological conditions or variations of artificial emission rate.Equations guiding the control of unorganized emission sources are derived for preventing air quality deterioration during urban expansion and population concentration.     

城市地震压埋人员分布评估研究——以天津市区为例

地震压埋人员分布是震后科学、有效地开展应急处置和救援的重要依据.针对地震中建筑物破坏造成的人员压埋,从人口分布和在室率着手,在社区级空间尺度上分时段建立人口数量、在室率和建筑物的对应关系;结合建筑物震害评估方法,构建地震压埋人员快速评估模型,并预评估天津市区各烈度下地震压埋人口的数量和分布情况.结果显示,夜间是发生地震...     

气汞的第一个同震效应记录

利用杭州超距科技有限公司最近研发的ATG-6138型测汞仪在云南省弥勒井气汞（Hg）观测中记录到尼泊尔8.1级地震的同震效应。这是我国气汞观测的第一个同震效应的纪录。这一事实表明了进一步提升地震地下流体化学量观测仪器的观测精度与采样率,有可能记录到固体潮与同震效应等更多的地壳动力作用信息,从而进一步提升其地震前兆监测能力。     

中国首台PET机的研制与正电子CT成像的新进展

正电子断面图像是最新的医学影象技术，它是通过研究正电子示踪核素标记的化合物在体内的动态分布，显示人体各部位的功能和代谢变化的图象。本文介绍正电子断层图的原理和应用以及我国科学工作者在推进中国ＰＥＴ研究工作的历程，重点介绍１９９２年以来我国第一台ＰＥＴ仪的研制过程、性能特点、应用概况及发展前景．