A modified normalized model for predicting effective soil thermal conductivity

Effective soil thermal conductivity (λ _eff) describes the ability of a multiphase soil to transmit heat by conduction under unit temperature gradient. It is a critical parameter for environmental science, earth and planetary science, and engineering applications. Numerous models are available in the literature, but their applicability is generally restricted to certain soil types or water contents (θ). The objective of this study was to develop a new model in the similar form of the Johansen 1975 model to simulate the λ _eff(θ) relationship of soils of various soil textures and water contents. An exponential type model with two parameters is developed and a new function for calculating dry soil thermal conductivity is presented. Performance of the new model and six other normalized models were evaluated with published datasets. The results show that the new model is able to well mimic λ _eff(θ) relationship of soils from sand to silt loam and from oven dry to full saturation. In addition, it has the best performance among the seven models under test (with root-mean-square error of 0.059 W m^?1 °C^?1, average deviations of 0.0009 W m^?1 °C^?1, and Nash–Sutcliffe efficiency of 0.994). The new model has potential to improve the reliability of soil thermal conductivity estimation and be incorporated into numerical modeling for environmental, earth and engineering studies.     

鹿井铀矿床铀矿物学特征

鹿井矿床位于南华活动带华夏褶皱带武功—诸广断隆区,闽、赣后加里东褶皱地块西缘,诸广山复式岩体中段,受遂川断裂及热水断裂组成的地堑式断陷带控制。本文主要对鹿井矿床内铀矿物的赋存状态、成分特征及组合特征进行了研究。     

地下夹塞断面形状随机性对平面SH波散射的影响

采用波函数展开法及边界离散的方法给出了任意断面形状的地下夹塞对平面SH波散射的半解析解; 利用蒙特卡罗方法随机模拟产生了30组夹塞断面样本, 通过对该样本在平面SH波入射下地表位移幅值的统计分析, 研究了夹塞断面形状随机性对平面SH波散射的影响. 结果表明, 夹塞断面形状随机性对平面SH波的散射具有重要影响. 以圆形夹塞为例, 当断面半径的变异系数为0.1时, 地表位移响应幅值变异系数可达0.71. 随着入射频率的升高, 变异系数逐渐增大; 随着夹塞刚度的降低, 变异系数逐渐增大; 随着夹塞埋深的增加, 变异系数逐渐减小.     

Migration and speciation transformation mechanisms of mercury in undercurrent zones of the Tongguan gold mining area,Shaanxi Loess Plateau and impact on the environment

In order to study the migration and transformation mechanism of Hg content and occurrence form in subsurface flow zone of gold mining area in Loess Plateau and its influence on water environment, the field in-situ infiltration test and laboratory test were carried out in three typical sections of river-side loess, alluvial and proluvial strata in Tongguan gold mining area of Shaanxi Province, and the following results were obtained: (1) The source of Hg in subsurface flow zone is mainly caused by mineral processing activities; (2) the subsurface flow zone in the study area is in alkaline environment, and the residual state, iron and manganese oxidation state, strong organic state and humic acid state of mercury in loess are equally divided in dry and oxidizing environment; mercury in river alluvial or diluvial strata is mainly concentrated in silt, tailings and clayey silt soil layer, and mercury has certain stability, and the form of mercury in loess is easier to transform than the other two media; (3) under the flooding condition, most of mercury is trapped in the silt layer in the undercurrent zone where the sand and silt layers alternate with each other and the river water and groundwater are disjointed, and the migration capacity of mercury is far less than that of loess layer and alluvial layer with close hydraulic connection; (4) infiltration at the flood level accelerates the migration of pollutants to the ground; (5) the soil in the undercurrent zone is overloaded and has seriously exceeded the standard. Although the groundwater monitoring results are safe this time, relevant enterprises or departments should continue to pay attention to improving the gold extraction process, especially vigorously rectify the small workshops for illegal gold extraction and the substandard discharge of the three wastes, and intensify efforts to solve the geological environmental problems of mines left over from history. At present, the occurrence form of mercury in the undercurrent zone is relatively stable, but the water and soil layers have been polluted. The risk of disjointed groundwater pollution can not be ignored while giving priority to the treatment of loess and river alluvial landform areas with close hydraulic links. The research results will provide a scientific basis for water conservancy departments to groundwater prevention and control in water-deficient areas of the Loess Plateau.     

强烈气洗作用导致原油成分变化的定量计算:以库车坳陷天然气藏为例

库车坳陷以产天然气为主,同时产出少量原油和凝析油,油气充注不同步,普遍具有"油早气晚"的特点,晚期大量天然气的侵入,必然对早期聚集的油藏发生改造作用。对气藏中原油成分变化的定量计算和讨论,可为天然气的注入强度定量评价提供直接证据。未遭受气洗的原油,正构烷烃摩尔浓度的对数与相应的碳数呈线性关系,而气洗作用可使轻组分的正构烷烃最先溶解于干气中,并随着天然气继续向前运移,原始油藏中的轻组分正构烷烃大大减少。以此为理论基础,建立了正构烷烃损失的定量计算模型。结果表明克拉2构造原油正构烷烃损失程度最高,平均可达70%左右,大北构造带原油正构烷烃损失程度差异较大,与该地区断块发育有关。气洗作用导致原油正构烷烃减少,而金刚烷、多环芳烃等在天然气中溶解度较低的化合物得以浓缩富集,相对含量大大增加。轻芳烃含量也会随之而增加,原油芳香度增加,石蜡度降低。在模拟实验基础上对气洗程度进行了定量评价,初步估算表明,克拉2构造原油遭受的气洗作用最强,是其他构造带的2～5倍。     

Rock Mass Characteristics in Beishan, A Preselected Area for China’s High-Level Radioactive Waste Disposal

Geological and hydrological characteristics, joint geometric features, rock physical and mechanical properties and rock mass quality are studied in the Beishan area, preselected for China’s high-level radioactive waste (HLW) disposal engineering. A comprehensive survey method is developed to study joint geometric features in the outcrop and samples from borehole BS06 into the Xinchang rock mass were tested. The optimal joint sets are determined by rose diagrams and equal-area lower hemisphere plots of joint poles. Results show that: 1) the distribution of joint occurrence obeys a normal distribution, while the distribution of joint spacing obeys a negative exponential distribution; 2) concentric circular and tangent circular sampling windows are applied to study the trace length and the trace midpoint density. Results indicate that tangent circular sampling window is more stable and reasonable; 3) Beishan granite shows high density, low porosity and high strength based on many laboratory tests and the physical properties and mechanical properties are closely related; and 4) a synthesis index, Joint Structure Rating (JSR), is applied to evaluate the quality of rock mass. Through the research results of rock mass characteristics, the Xinchang rock mass in the Beishan preselected area has the favorable conditions for China’s HLW disposal repository site.     

青藏高原近60年来气候变化及其环境影响研究进展

作为全球能量水分循环的关键区域,青藏高原(下称高原)气候变化对高原及周边地区气候与环境变化具有重要影响.本文从高原表面增暖、辐射变化、降水的多尺度变率、表面风速及环境变化方面回顾了高原近60年来气候变化及其环境效应与物理机制的研究进展,并基于再分析和台站观测资料讨论了近10余年来高原表面温度和风速变化的特征及原因.最后...     

微波等离子体炬质谱技术快速鉴别天然石材与人造石材

天然石材主要有大理石、花岗岩等;人造石材多以不饱和聚酯树脂为基料,添加适量的无机物粉料和添加剂固化制成。由于石材种类繁多,并且各种石材的岩体所含矿物成分也有差异,当前很少应用化学成分分析方法准确、快速鉴别天然和人造石材,仅有的红外光谱法由于对待测物纯度的要求较高而具局限性。本文基于微波等离子体炬源(MPT)同时具有热解吸与强电离能力,能在短时间内离子化待测物的特点,采用微波等离子体炬质谱(MPT-MS)技术,无需样品复杂预处理直接对天然与人造石材进行分析,获得正离子检测模式下在m/z 50~1000之间的石材的指纹谱图,并运用化学计量学的主成分分析(PCA)方法处理所获取的数据,实现了不同建筑石材的区分。结果表明,MPT-MS能够获得石材丰富的指纹谱图,结合PCA方法能够快速鉴别天然石材与人造石材,天然石材中解吸出的物质主要为CO₂和H₂O的团簇分子;而人造石材中解吸出的主要成分为有机物(人为添加的黏合剂等)。本研究采用的MPT-MS技术无需采用喷雾、激光、基质和加热等方法辅助,并且无需对石材进行任何复杂的处理即可进行质谱分析,从而获取石材表面及内部物质的质谱信息,为快速直接鉴定石材样品提供了一种新的质谱分析方法。     

秦岭泥盆系硅岩岩石类型对比研究

硅岩可以通过化学沉积（真溶液或胶体沉淀）和内碎屑堆积而成。由于热水有较强的化学活动性，因而在水岩界面附近也会形成交代成因的硅岩。在许多情况下，硅岩既具有沉积岩的岩石学特征，又具有交代岩的岩石学特征，其成岩环境十分特殊。因此，虽然有许多地球化学方法可以区分不同类型的硅岩，但岩石学特征是最基本的和最直接的标志。     

贵州册亨岩架黑苗湾组的发现及其地质意义

作者在册亨尾排金矿普查地质填图工作中,于岩架镇高苕一带发现晚三叠世卡尼早期地层.根据岩性特征,将其划为黑苗湾组.本文对该地黑苗湾组的出露与分布及岩石地层特征进行详细介绍,并讨论其地质意义.