Numerical simulation of the impact of urban non-uniformity on precipitation

To evaluate the influence of urban non-uniformity on precipitation, the area of a city was divided into three categories (commercial, high-density residential, and low-density residential) according to the building density data from Landsat satellites. Numerical simulations of three corresponding scenarios (urban non-uniformity, urban uniformity, and non-urban) were performed in Nanjing using the WRF model. The results demonstrate that the existence of the city results in more precipitation, and that urban heterogeneity enhances this phenomenon. For the urban non-uniformity, uniformity, and non-urban experiments, the mean cumulative summer precipitation was 423.09 mm, 407.40 mm, and 389.67 mm, respectively. Urban non-uniformity has a significant effect on the amount of heavy rainfall in summer. The cumulative precipitation from heavy rain in the summer for the three numerical experiments was 278.2 mm, 250.6 mm, and 236.5 mm, respectively. In the nonuniformity experiments, the amount of precipitation between 1500 and 2200 (LST) increased significantly. Furthermore, the adoption of urban non-uniformity into the WRF model could improve the numerical simulation of summer rain and its daily variation.     

常州市地面沉降以及用水化学标志研究的探讨

常州市过量开采第Ⅱ承压含水层的水使水位大幅度下降,造成含水砂层压密和粘性土层固结而导致地面沉降。试验资料表明该区粘性土层的压缩性较低,它们的压密主要是由主固结阶段完成的。视压榨液,浸提液成分和含水层多年水质的变化,以及抽水时水质与氚量资料说明粘性土层释水在造成本区地面沉降中起着相当重要的作用。这种条件下,用对含水层水化学成分的检测来监视地面沉降的发生、发展是一个经济可靠的方法。     

Juxtaposition of adakite, boninite, high-TiO2 and low-TiO2 basalts in the Devonian southern Altay, Xinjiang, NW China

We present petrographic and geochemical data on representative samples of the Devonian adakite, boninite, low-TiO₂ and high-TiO₂ basalts and associated rocks in the southern Altay areas, Xinjiang, NW China. These volcanic rocks mostly occur as tectonic blocks within suture zones between the Siberian and Junggar plates. Adakite occurs in the Suoerkuduke area ca. 40 km south of Fuyun, and actually represents a poorly-sorted massive volcaniclastic deposit, mostly consisting of a suite of hornblende andesite to pyroxene andesite. The geochemical features of the adakite suggest its generation by melting of subducted oceanic crust. Boninite occurs in the Saerbulake area ca. 20 km southwest of Fuyun, as pillowed lava or pillowed breccia. It is associated with high-TiO₂ basalt/gabbro and low-TiO₂ basalt. The boninites are metamorphosed, but contain relict clinopyroxene with Mg# (=100*Mg/(Mg+Fe)) of 90–92, and Cr₂O₃ contents of 0.5–0.7 wt% and chromian spinel with Cr/(Cr+Al) ratio of 0.84. The bulk rock compositions of the boninites are characterized by low and U-shaped REE with variable La/Yb ratios. They are classified as high-Ca boninite. The Cr-rich cpx phenocryst and Chromian spinel suggests that the boninites were formed by melting of mildly refractory mantle peridotite fluxed by a slab-derived fluid component under normal mantle potential temperature conditions. Basaltic rocks occur as massive flows, pillowed lavas, tuff breccia, lapilli tuff and blocks in tectonic mélanges. Together with gabbros, the basaltic rocks are classified into high-TiO₂ (>1.7 wt%) and low-TiO₂ (<1.5 wt%) types. They show variable trace element compositions, from MORB-type through transitional back-arc basin basalt to arc tholeiite, or within plate alkalic basalt. A notable feature of the Devonian formations in the southern Altay is the juxtaposition of volcanic rocks of various origins even within a limited area; i.e. the adakite and the boninites are associated with high-TiO₂ and low-TiO₂ basalts and/or gabbros, respectively. This is most likely produced by complex accretion and tectonic processes during the convergence in the Devonian–Carboniferous paleo-Asian Ocean between the Siberian and Junggar plates.     

应用近红外光谱法研究泻湖湿地沉积物重金属活动态特征及生态风险评价

沉积物中的重金属元素经自然作用下可以活动态进行迁移,具有潜在生物可利用性及潜在的区域生态风险。利用近红外光谱(NIRS)技术开展不同基体类型样品响应机理研究,可为评估重金属活动态提供无损、快速的分析方法,为生态风险研究提供依据。天津七里海泻湖湿地沉积物具有低有机质-高黏土含量的特征,本文基于近红外光谱分析技术,建立了沉积物中Co、Ni、Cu、Zn、Cd、Pb重金属活动态组分含量近红外光谱-偏最小二乘回归预测模型。实验结果表明:样品在7290～6390cm~(-1)和4683～4000cm~(-1)波段存在的双羟基O—H伸缩振动、AlAl—OH及Al(Mg)—OH弯曲振动特征吸收,间接指示了重金属元素活动态含量。光谱预测结果显示,近百年来七里海沉积物中Co、Ni、Cu、Zn、Cd、Pb活动态组分的变化特征对应了当地1934—1948年、1956—1963年、1976年至今三次较明显的升温过程,也对应了1980年七里海水库建设等大型人为扰动。本研究样品中Co、Ni、Cu、Zn、Cd、Pb总量及活动态均低于国家标准中规定的生态风险阈值,七里海内村镇及周边农田来自湿地释放的重金属生态风险极低。     

Chloride as tracer of solute transport in the aquifer–aquitard system in the Pearl River Delta,China

A 1D numerical model is constructed to investigate the impact of sedimentation and sea level changes on transport of Cl^? in the aquifer–aquitard system in the Pearl River Delta (PRD), China. The model simulates the evolution of the vertical Cl^? concentration profiles during the Holocene. Sedimentation is modeled as a moving boundary problem. Chloride concentration profiles are reconstructed for nine boreholes, covering a wide area of the PRD, from northwest to southeast. Satisfactory agreement is obtained between simulated and measured Cl^? concentration profiles. Diffusion solely is adequate to reproduce the vertical Cl^? concentration profiles, which indicates that diffusion is the regionally dominant vertical transport mechanism across the aquitards in the PRD. The estimated effective diffusion coefficients of the aquitards range from 2.0?×?10^–11 to 2.0?×?10^–10 m²/s. The effective diffusion coefficients of the aquifers range from 3.0?×?10^–11 to 4.0?×?10^–10 m²/s. Advective transport tends to underestimate Cl^? concentrations in the aquitard and overestimate Cl^? concentrations in the basal aquifer. The results of this study will help understand the mechanisms of solute transport in the PRD and other deltas with similar geological and hydrogeological characteristics.     

再论臼齿碳酸盐岩成因

臼齿(Molar Tooth,简称MT)碳酸盐岩是产于元古代、并具有特殊全球性意义的碳酸盐岩类型之一.MT特有的微亮晶结构、严格的时空分布范围以及百余年来众多的成因解释,一直吸引着国内外地质学家对其进行持续的研究和探讨.作者在前人研究基础上,基于作者近10余年成果积累及新近对MT微观组构的研究进展,提出了若干新认识.M...     

塔里木盆地震旦—泥盆纪古海平面变化再造及形成机理分析

根据对塔里木盆地露头剖面的层序地层学研究，建立了震旦—泥盆纪古海平面变化曲线。详细分析了氧同位素记录与海平面变化之间的关系，得出了：氧同位素值的增大、减小反映着古海平面的下降、上升的变化的结论。用氧同位素分析结果验证了根据层序地层分析所建立的海平面变化曲线的正确性。并利用氧同位素分析结果定量计算了古海平面的变化幅度。最后阐述了古海平面变化的形成机理。     

羌塘天然气水合物地震干扰波特征分析及去噪方法

基于西藏羌塘盆地天然气水合物原始资料,对地震干扰波类型进行分析,从不同道集域、频率、速度、能量等方面分析干扰波的特征,针对强能量干扰、面波、次生干扰波及随机噪声在单炮记录上的特点,经反复测试,总结出压制各种干扰波的合适方法及相应去噪模块相组合方式,在实际处理中取得了明显效果。叠前去噪需要把握好尺度,尽可能地保护有效信息不受损失;压制干扰波需遵循循序渐进的方式,分步处理,先强后弱,先线性后随机,形成一套去噪流程,并联合使用多种技术方法。实践证明,上述方法对羌塘盆地的干扰波压制十分有效。     

Status and Advances of Abandoned Process of Wells for CO2 Geological Storage

With the rapid development of CO₂ geological storage and utilization (CCS/CCUS), the abandoned well in the sites of CCS/CCUS projects is becoming an important subject to be solved to check whether it can effectively block the residual CO₂ or not. Up to now, the abandoned process of wells in the field of oil and gas in China and abroad have gained mature operation technology and rich experience. However, in the field of CCS/CCUS, there is only a small number of global public instances about the abandoned process of operational wells of CO₂ including CO₂ injection wells and CO₂ monitoring wells, and the domestic instance is still blank. In this paper, we firstly summarized the required demands, materials, cases of operational experiences, and monitoring requirements of the abandoned process of operational wells of CO₂ in the developed countries, e.g. the Netherlands, the United States and Canada. Then, we figured out the status of the abandoned process of domestic wells in oil and gas industry. Finally, we concluded the differences of the abandoned process between operational wells of CO₂ and traditional wells of oil and gas, and proposed some recommendations for the abandoned process of operational wells of CO₂ in the current and future CCS/CCUS projects in China. This study has important implications for the upcoming abandoned process of all the operational wells at Shenhua CCS demonstration site in 2016.     

川东石炭系新区天然气开发早期动态预测模型

川东石炭系新区大多数气藏尚未进入或结束评价阶段,资料不足而不具行进行数值模拟编制早期开发方案的条件,为了高速高效开发气藏及编制矿区上产规划,就必须选择适当的方法进行新区早期动态预测,本文正是基于此,特提出递推滚动ＢＰ神经网络预测模型,利用老区不同类型气藏的已建模型,对新区不同采气速度下,稳产期和递减期地层压力的变化规律,最终采出程度的大小进行了预测,预测精度与传统的数值模拟方法相当,更具有简便快速