叠前时间偏移方法在煤田勘探中的应用

根据克希霍夫积分法的原理,介绍了叠前时间偏移的方法特点,实现过程,以及对地震资料的要求,依托国家重大产业技术专项“西部煤炭资源高精度三维地震勘探”工程,对“青海省鱼卡煤田四井田高精度三维地震勘探”资料进行叠前时间偏移,结果表明其能较好地解决成像质量差、能量聚焦不明显、绕射波收敛不理想等方面的难题。通过与叠后时间偏移对比,对于大倾角地层、断块小且多的破碎带、陡倾角不对称向斜等地质问题,其叠前时间偏移剖面成像质量都有明显的提高,反映的构造关系更加清晰,同相轴连续性增强。总结该方法在多个矿区的推广经验．认为合理的观测系统、较高的资料信噪比,准确的测量资料及较高的中表层速度调查精度是做好叠前时间偏移的前提。     

Chromium speciation in oxide-type compounds: application to minerals,gems, aqueous solutions and silicate glasses

Cr K-edge XANES spectra were obtained for a variety of Cr-bearing model compounds containing Cr(II), Cr(III), Cr(IV), Cr(V) and Cr(VI), in which the Cr-site symmetry is D4h, Oh and Td. The centroid position of the pre-edge feature is a better indicator of the Cr valence than the edge position. In Cr-rich oxides, higher-energy transitions must be excluded in order to refine a robust valence for Cr. The pre-edge for chromates is not unique and varies as a function of the CrO₄ ^2? moiety distortion, which is often related to Cr-polymerization (monochromate vs. dichromate). Both the analogy with the Mn K-pre-edge information and ab initio FEFF calculations of the pre-edge feature for Cr(III) and Cr(VI) confirm the experimental trends. This methodology is applied to the Cr K-edge pre-edge feature collected in gems (emerald, spinel and ruby), the layered minerals fuchsite and kämmererite, two Cr-bearing aqueous solutions and a set of sodo-calcic silicate glasses used for bottling sparkling white wine. In emerald and fuchsite, the Cr-site is differently distorted than its ruby or spinel counterpart. In a Cr(III)-bearing aqueous solution and sodo-calcic glass, no evidence for Cr(III) with Td and C3v symmetry is detected. However, minor amounts of chromate moieties (most likely monomeric) are detected in a glass synthesized in air. Preliminary spectra for the wine bottle glass suggest that only trace amounts of chromates might possibly be present in these glasses.     

An application of a new method in permafrost environment assessment of Muli mining area in Qinghai-Tibet Plateau,China

The permafrost environment in the Muli mining area, an opencast mining site in the Qinghai-Tibet Plateau, China, is now undergoing significant degradation because of the ongoing mining activities. The permafrost environment in this mining site had already been evaluated by previous study, in which analytic hierarchy process was applied. Although this method can roughly characterize the permafrost environment of this mining site, it has limitations by being easily affected by man-made factors. In view of this limitation, this study attempts to employ a new method, the catastrophe progression method, to estimate the current stage of the permafrost environment in this mining area. The results show that, by catastrophe progression method, currently the calculated indexes of the permafrost freezing–thawing disintegration, permafrost thermal stability, permafrost ecological fragility, and the permafrost environment are 0.43 (general situation), 0.77 (general situation), 0.71 (bad situation) and 0.83 (general situation), respectively. These values imply that the permafrost environment has been damaged by anthropologic activities to a certain degree and potentially may be further degenerated. However, at this degree, a new equilibrium stage of permafrost environment could be achieved if the current state of environmental degradation is stabilized and treatments are constructed against further damages.     

REE Geochemistry of the Lead—Zinc Ores from the Jinding Lead—Zinc Deposit,Lanping,Yunnan

Nineteen volcanic and magmatic rock samples were collectecd from the Jinding leadzinc deposit and its surrounding areas in Yunnan.The ICP and AES analyses,feferred to the previous results,show that the metal minerals and altered rocks in the Jinding lead-zinc deposit display a decreasing trend of ∑REE from the early to late stages of mineralization,and similarities in REE distribution patterns,indicating that the ore fluids are characterized by high LREE enrichment,markedly negative δCe anomaly and slight δEu anomaly.These REE distribution paterns exhibit striking similarities to those of the Pliocene trachyte in the study area,both of which are similar in ∑REE,LREE/HREE ratio,δEu and δCe.The ore fluids besides the basin fluids in the deposit are also closely related to those associated with Pliocene trachyte magmas.     

Assessing the vulnerability of social–environmental system from the perspective of hazard,sensitivity, and resilience: a case study of Beijing,China

Despite a recent increase in the number of vulnerability analyses there has been relatively little discussion of vulnerability assessment of social–environment system, especially when they face multiple hazards. In this study, we developed an applicable and convenient method to assess vulnerability of social–environment system at a regional scale. Vulnerability is quantified by measuring three critical elements (i.e. hazards, sensitivity, and resilience) through some key variables. The results showed that vulnerability is high in Miaofeng Mountain in Mengtougou District, the hills of Pinggu County and the riparian zones of the lower courses of the Beiyun and Yongding Rivers; but low in the city of Beijing and the southwestern part of the Fangshan District. Areas of very high, high, medium, and low-vulnerability account for 6.19, 25.48, 33.06, and 35.27% of the total area, respectively. The degree of vulnerability decreases in a northwest direction in mountainous areas and declines from watercourses to riparian zones along a lateral direction in the plain. Some adaptive strategies are also proposed.     

Isotope evidence for quantifying river evaporation and recharge processes in the lower reaches of the Yellow River

Evaporation and recharge are important hydrological processes in the water cycle. However, accurately quantifying these two processes of river remains to be difficult due to their spatial heterogeneity and the limitations of traditional methods. In this study, a more reliable method of stable isotopes of δ ¹⁸O and δ ²H based on the Rayleigh distillation equation and mass conservation was used to estimate the evaporation and recharge of the rivers in the lower reaches of the Yellow River, North China Plain. Comprehensive sampling campaigns including 30 surface water samples from 10 rivers, 33 groundwater samples from domestic and observation wells, and two Yellow River water samples were conducted. The results showed that the evaporation proportion of the rivers based on δ ¹⁸O and δ ²H both averaged 14.4%. The evaporation proportions in each river did not completely follow a linear increasing trend along the flow path. This phenomenon could be mainly explained by the different proportions of recharge from groundwater and Yellow River water. With closer to the Yellow river, evaporation of the rivers decreased while the recharge by the Yellow River increased. Regression equations based on δ ¹⁸O, δ ²H, and their average revealed that the evaporation proportion respectively increased by 1.02, 0.79, and 0.90% with the increase in the distance to the Yellow River per 10 km. On the contrary, the recharge proportion decreased by 7.68, 5.51, and 6.59%, respectively. In addition, using δ ¹⁸O rather than δ ²H was more reliable in studying the spatial influence of the Yellow River on evaporation and recharge. Sensitivity analysis showed that the evaporation model was most sensitive to isotopic composition, rather than to air temperature or relative humidity. The results of this study provide insights into the determination of river hydrological processes and the management of water resources.     

Heavy metals distribution in agricultural topsoils in urban area

Intensive urbanisation of the Croatian capital of Zagreb has led to a situation where very good agricultural soils, developed mostly on Pleistocene eolian sediments and alluvial and proluvian Holocene sediments are entrapped within urban and suburban areas. Therefore the influence of urban and industrialised environments on the accumulation of metals in agricultural topsoils has been investigated. On an area of 860 km² of the wider Zagreb region, 331 samples were taken according to a regular 1ǵ km square mesh. Samples were dissolved in aqua regia and analysed for Cd, Cu, Fe, Mn, Ni, Pb and Zn with flame atomic aqua regia absorption spectroscopy. The following concentration ranges have been determined: Cd 0.25-3.85 mg kg^-1 (average 0.66 mg kg^-1), Cu 4.30-183 mg kg^-1 (average 20.8 mg kg^-1), Fe 5.8-51.8 g kg^-1 (average 27 g kg^-1), Mn 79.2-1282 mg kg^-1 (average 613 mg kg^-1), Ni 0.70-282 mg kg^-1 (average 49.5 mg kg^-1), Pb 1.50-139 mg kg^-1 (average 25.9 mg kg^-1), and Zn 15.2-277 mg kg^-1 (average 77.9 mg kg^-1). Visualisation of the spatial data is made by the aid of GIS, and selected maps of the heavy metal concentrations in topsoils are displayed. Statistical multivariate analysis was carried out for quantitative study and data were processed by means of R-mode factor analysis, applying the varimax-raw rotational technique. F1, which grouped Cd, Pb, Cu, Zn and partially Ni, is characterized as a factor with strongly scattered anthropogenic influence. The elements in F2, Fe, Mn and partially Ni are mainly of geogenic, i.e. pedogenic, origin. The variations in concentrations of the investigated elements are thus of both natural and anthropogenic origins. The variations in the main soil constituents, particularly Fe and Mn, are determined primarily by the composition of different regolithic substrates of the fluvial origin in recent pedogenesis. High concentrations of nickel are also related to morphogenetic characteristics of the wider region, primarily basic and ultrabasic magmatic rocks of the surrounding mountain range. It is, however, assumed that the anomalous nickel concentrations in the vicinity of the highway and the airport are of anthropogenic origin, i.e. caused by fuel combustion. Copper is characterized by strongly scattered anthropogenic influence, which is related particularly to uncontrolled solid waste disposals or discharges of liquid waste from households or agricultural enterprises. With Zn, Pb and Cd, there are two possible ways of diffuse pollution. The Sava River, which drains the area and feeds the abundant Quaternary aquifer spreading below the major part of the investigated agricultural areas, has been exposed to intensive pollution by mining, industry and cities in the recent history. The part of the area with the highest determined concentrations of Zn, Pb and Cd was repeatedly flooded as recently as the previous decade; therefore, the recent sedimentation of the river deposits exposed to pollution is a very probable cause of the accumulation of metals in this until recently inundation area. The other way is atmospheric deposition of particles from urban sources (industrial emission, traffic, waste disposals, heating plants, etc.). In addition to agricultural enterprises, several economically important, but ecologically risky, facilities are situated in the vicinity of the water-protection area. The area is intersected by a very busy ring road, while a marshalling yard, the city dump, pharmaceutical and chemical industry, the district-heating plant and the airport are all located in close proximity. The geochemical maps show a clear relationship between human activities and metal concentration gradients.     

Structural improvement of age-hardened gypsum-treated bauxite red mud waste using readily decomposable phyto-organics

Several years (7) after incidental lithification by added gypsum, the effect of crushing and phyto-organics on some physical properties of red mud wastes (RMW) was examined under laboratory conditions. It was hypothesized that mechanically breaking up the hardened masses would increase their permeability. However, on the contrary, crushing these rock-hard masses into <2-mm particles did not increase permeability. A phyto-organic treatment on the other hand greatly improved permeability of the crushed entities such that infiltration rates increased from 0 to 10 cm/h. After 24 weeks of incubation, the structure of the newly formed phyto-organically treated gypsum-hardened RMW aggregates was also substantially improved over that of the controls, as a >3-fold increase in resistance to disintegration during wet sieving was exhibited by the phyto-organically treated samples. The increase in water infiltration by combining crushing with phyto-organic applications was ascribed to a decrease in particle dispersion, creating more stable clay clusters, which in turn stabilized channels and pores. Conversely, it was concluded that the singular crushing of gypsum-hardened bauxite waste in the waste dumps is potentially wasteful and ineffective.     

钻杆接头材料35CrMo硫氮复合处理层的干摩擦学性能研究

应用离子渗氮与离子渗硫技术,在钻杆接头材料35CrMo钢表面制备了硫氮复合处理层。采用M-200环块磨损试验机,对比研究了原始渗氮表面与硫氮复合表面在干摩擦条件下的抗磨损性能。结果表明,在干摩擦的条件下,由于摩擦副的接触表面缺乏润滑,硬度较高的渗氮层会加剧接触表面的磨损。而硫氮复合处理层由于在表面存在一层硫化亚铁固体润滑层,在磨损过程中可以起到一定的润滑作用,因此其在干摩擦条件下具备更好的抗磨损性能。     

Farmers＇ vulnerability to flood risk： A case study in the Poyang Lake Region

This paper quantitatively explores farmers＇ vulnerability to flood in the Poyang Lake Region （PLR） with the supports of GIS spatial functions. The analysis consists of three major steps, which is based on the spatial unit of township. Firstly, the spatial extent and characteristics of flood risk areas were determined using a digital elevation model （DEM） derived from the 1：50,000 topographic map. Secondly, for each of the township, six indices indicating the economic activities of local farmers were calculated. These indices are： rural population proportion, cultivated land proportion, GDP per unit area, employment proportion of primary industry, net rural income per capita and agricultural income proportion. These six indices were then normalized and used for later vulnerability assessment. Thirdly, the normalized indices （as GIS data layers） were overlaid with the flood risk areas to produce the risk coefficient for each township and to calculate the overall vulnerability for each township. The analysis results show that in the PLR there are high flood risk areas where the farmers＇ livings are seriously influenced or threatened. About 55.56% of the total 180 townships in the flood risk areas have a high degree of flood vulnerability. The townships under flood risk are mainly distributed in the areas around the Poyang Lake and the areas along the ＂five rivers＂.