Hydrocarbon composition and distribution in a coastal region under influence of oil production in northeast Brazil

Waters and sediments from the Potiguar Basin (NE Brazilian coast) were investigated for the presence and nature of polycyclic aromatic hydrocarbons (PAH) and aliphatic hydrocarbons. The region receives treated produced waters through a submarine outfall system serving the industrial district. The total dispersed/dissolved concentrations in the water column ranged from 10-50 ng L⁻¹ for ∑16PAH and 5-10 μg L⁻¹ for total aliphatic hydrocarbons. In the sediments, hydrocarbon concentrations were low (0.5-10 ng g⁻¹for ∑16PAH and 0.01-5.0 μg g⁻¹ for total aliphatic hydrocarbons) and were consistent with the low organic carbon content of the local sandy sediments. These data indicate little and/or absence of anthropogenic influence on hydrocarbon distribution in water and sediment. Therefore, the measured values may be taken as background values for the region and can be used as future reference following new developments of the petroleum industry in the Potiguar Basin.     

重庆地区近10年酸雨时空分布和季节变化特征分析

利用2005年重庆各区县31个观测站降水的pH值资料分析了当年整个地区的降水酸度的空间分布和季节变化特征,并选取中国气象局酸雨观测网中沙坪坝、涪陵、万县、奉节和巴东5个观测站点1997年至2006年的酸雨观测数据,对重庆地区近10年来酸雨的时空分布特征和季节变化情况进行了统计分析.研究结果表明:重庆地区降水酸性和电导率的地区间差异较大,降水酸性的季节变化较明显,冷季(秋、冬)较暖季(春、夏)要强.西南部降水酸性较强,受污染程度也较严重,但没有明显的变化趋势;东北部大多为弱酸性降水,且受污染程度也较轻,但是日趋酸化和污染加重的趋势却较明显,且季节变化尤为明显,其中夏秋两季pH值的明显减小是其近10年来酸化加重的主要原因.涪陵的数据明显不同,酸性降水频率较低,pH值偏高的同时电导率也偏高,2001年前后情况尤为明显,可能受局地因素的影响比较大.     

Unusual Mantle Mineral Group from Chromitite Orebody Cr-11 in Luobusa Ophiolite of Yarlung-Zangbo Suture Zone, Tibet

A wide variety of unusual mantle has been reported from podiform chromitite orebodies Cr-31 and Cr-74 in the Luobusa (罗布莎) ophiolite, Tibet. A detailed investigation of chromitite ore-body Cr-11, located in the Kangjinla (康金拉) district at the eastern end of the ophiolite, has revealed many of the same minerals, including diamond, moissanite, and some native elements, alloys, oxides, sulphides, silicates, carbonates, and tungstates. This orebody is particularly rich in diamonds, with over 1 000 grains recovered from about 1 100 kg sample of chromitite. More detailed studies and experi-ments are needed to understand the origin and significance of these unusual minerals because they have not been found in situ. It is a great breakthrough in mineralogical research that we have picked up more than 40 kinds of minerals from the Kangjinla chromite deposit in Luobusa. It is notable that a large amount of diamonds were firstly discovered from the Kangjinla chromite deposit as well as many other unusual minerals, such as moissanites, rutiles, native irons, and metal alloys. Especially, that diamond was found again in different chromitites In the same ophiolite belt provided new key evidence for discussing the origin of the diamond and the hosted ehromitite and ophiolite. The mantle mineral group in Tibet has great significance in mineralogy and geodynamics.     

The relative deformation gradient and its application to cylindrical folds with deformed lineations

The relative deformation gradient is defined and used to compare deformations between any two points of a body. This concept is useful in the geometrical analysis of deformation in natural folds, where only deformed planes and straight lines can be observed. The case of cylindrical folds with deformed lineations is studied.     

Drained-to-undrained transition of bulk modulus in fluid-saturated porous rock induced by dead volume variation

We examine the effect of poroelastic boundary conditions when determining elastic properties of fluid-saturated porous rocks from forced-oscillation laboratory experiments. One undesired yet often unavoidable complication in the estimation of the undrained bulk modulus is due to the presence of the so-called dead volume. It implies that some fluid mass can escape the rock sample under applying a confining pressure perturbation. Thus, the dead volume compromises the undrained state required to unambiguously determine the undrained bulk modulus. In this paper, we model data of recently performed low-frequency (0.1 Hz) measurements. Therein, the dead volume has been systematically varied from 10% to 1000% of the pore volume. For the smallest dead volume, the inferred bulk modulus is close to the Biot–Gassmann undrained bulk modulus. With increasing dead volume, the experimentally inferred bulk modulus approaches the drained bulk modulus. We show that the transition from undrained to drained state as a function of dead volume can be modelled with a 1D poroelastic model for the rock sample-dead volume system with a boundary condition that honours the continuity of the fluid volume flux. We discuss the limitations of the 1D model when applied to data recorded at higher frequencies (up to 100 Hz).     

Hydrochemical and isotopic properties of Heybeli geothermal area (Afyon,Turkey)

The thermal waters at the Heybeli (K?z?lkirse) low-temperature geothermal field located in the Afyonkarahisar Province (western Turkey) are discharged from Paleozoic recrystallized limestone. The temperature, specific electrical conductivity, and pH values of the thermal waters are within the range of 28.9 to 54.7 °C, 587 to 3580 μS/cm, and 6.32 to 7.37, respectively. The Heybeli geothermal system is fed by meteoric waters. The waters are heated at depth by high geothermal gradient caused by the neotectonic activity in the deep and ascend to the surface through fractures and faults by convection. The thermal waters are of Na-Ca-HCO₃-SO₄ type and their chemical composition of the waters is mainly controlled by water-rock interaction and mixing processes. The δ¹⁸O, δ²H and tritium compositions show that the thermal waters are of meteoric origin and the residence time at the reservoir is longer than 50 years. Isotope data (δ³⁴S and δ¹³C) indicate recrystallized limestones as origin of CO₂ and structural substitution of sulfate into marine carbonates (CAS) as origin of sulfur. Chemical, \( {\updelta}^{18}{\mathrm{O}}_{\left({\mathrm{SO}}_4-{\mathrm{H}}_2\mathrm{O}\right)} \) isotope geothermometers and mineral equilibrium diagrams applied to thermal waters gave reservoir temperatures between 62 and 115 °C. Saturation index calculations show that the most expected minerals causing scaling at outflow conditions during the production and utilization of Heybeli geothermal waters are calcite, aragonite, dolomite, quartz, and chalcedony.     

High-resolution simulations for Vietnam - methodology and evaluation of current climate

To assist the government of Vietnam in its efforts to better understand the impacts of climate change and prioritise its adaptation measures, dynamically downscaled climate change projections were produced across Vietnam. Two Regional Climate Models (RCMs) were used: CSIRO’s variable-resolution Conformal-Cubic Atmospheric Model (CCAM) and the limited-area model Regional Climate Model system version 4.2 (RegCM4.2). First, global CCAM simulations were completed using bias- and variance-corrected sea surface temperatures as well as sea ice concentrations from six Coupled Model Intercomparison Project Phase 5 (CMIP5) global climate models. This approach is different from other downscaling approaches as it does not use any atmospheric fields from the GCMs. The global CCAM simulations were then further downscaled to 10 km using CCAM and to 20 km using RegCM4.2. Evaluations of temperature and precipitation for the current climate (1980-2000) were completed using station data as well as various gridded observational datasets. The RCMs were able to reproduce reasonably well most of the important characteristics of observed spatial patterns and annual cycles of temperature. Average and minimum temperatures were well simulated (biases generally less than 1oC), while maximum temperatures had biases of around 1oC. For precipitation, although the RCMs captured the annual cycle, RegCM4.2 was too dry in Oct.-Nov. (-60% bias), while CCAM was too wet in Dec.- Mar. (130% bias). Both models were too dry in summer and too wet in winter (especially in northern Vietnam). The ability of the ensemble simulations to capture current climate increases confidence in the simulations of future climate.     

Comment on “Comparison of the Ability of ARIMA,WNN and SVM Models for Drought Forecasting in the Sanjiang Plain,China” by Yuhu Zhang,Huirong Yang,Hengjian Cui,and Qiuhua Chen,in Natural Resources Research DOI: 10.1007/s11053-019-09512-6

Natural Resources Research - We thank Zhang et al. (Nat Resour Res, 2019. https://doi.org/10.1007/s11053-019-09512-6) for investigating the accuracy of artificial intelligence techniques in the...     

基于CPU-GPU异构并行的复杂场地近断层地震动谱元法模拟

利用基于CUDA编程平台实现的工作站级CPU-GPU异构并行方法开展了实际场地近断层地震动谱元法模拟.通过模拟SECE/USGS提供的自发破裂模型TPV15,测试了工作站级CPU-GPU异构并行方法的计算精度与计算效率,并将该方法应用于1679年三河—平谷M8.0地震的强地面运动模拟,以证实该方法对真实设定地震动模拟的...