活性炭从硫脲浸出液中回收金的工艺研究

本文研究了在酸性硫脲浸出液中活性炭回收金的工艺过程,实验表明,在该浸出液中活性炭对金具有较高的吸附速度、吸附率和吸附容量并易于解吸,为工业应用提供了可靠的技术依据。     

郯庐断裂带及两侧地区强震异常特征分析

对郯庐断裂带及两侧的山东、辽宁、河北、江苏、江西等地区1966～2005年发生的24次中强以上地震的前兆观测异常,从异常持续时间、空间分布、时空相关性、异常形态、幅度特征、异常种类和可靠性等方面进行了系统的统计和分析,结果表明：①7级和6级地震中期异常最多,短期异常其次,临震异常最少。5级地震短期异常最多,其次是临震异常,中期异常最少;②异常具有阶段性特征,部分中期和短期地震前兆异常在发展过程中出现了短期或临震异常;③异常发展具有准同步性,越临近发震,异常转折项目越多;④异常主要出现在震中距100km范围内,在空间上具有相对集中性,且震中距越小,异常台项比越高;⑤异常空间分布与构造走向比较一致,显示出与构造较好的相关性;⑥异常持续时间与震中距之间没有显著的相关性;⑦震级越大,同一观测手段的异常幅度相对越大;⑧流体学科异常最多,其次是形变、电磁;⑨不同学科的异常均表现为中、短期异常为主,少数短临异常;⑩流体、形变和电磁学科较可靠异常数量均约为可靠异常的1倍。     

Characteristics of particle size for creeping and saltating sand grains in aeolian transport

Creep and saltation are the primary modes of surface transport involved in the fluid‐like movement of aeolian sands. Although numerous studies have focused on saltation, few studies have focused on creep, primarily because of the experimental difficulty and the limited amount of theoretical information available on this process. Grain size and its distribution characteristics are key controls on the modes of sand movement and their transport masses. Based on a series of wind tunnel experiments, this paper presents new data regarding the saltation flux, obtained using a flat sampler, and on the creeping mass, obtained using a specifically designed bed trap, associated with four friction velocities (0·41, 0·47, 0·55 and 0·61 m sec^?1). These data yielded information regarding creeping and saltating sand grains and their particle size characteristics at various heights, which led to the following conclusions: (i) the creeping masses increased as a power function (q = ?1·02 + 14·19u_*³) of friction wind velocities, with a correlation (R²) of 0·95; (ii) the flux of aeolian sand flow decreases exponentially with increasing height (q = a exp(–z/b)) and increases as a power function (q = ?26·30 + 428·40 u_*³) of the friction wind velocity; (iii) the particle size of creeping sand grains is ca 1·15 times of the mean diameter of salting sand grains at a height of 0 to 2 cm, which is 1·14 times of the mean diameter of sand grains in a bed; and (iv) the mean diameter of saltating sand grains decreases rapidly with increasing height whereas, while at a given height, the mean diameter of saltating sand grains is positively correlated with the friction wind velocity. Although these results require additional experimental validation, they provide new information for modelling of aeolian sand transport processes.     

Source and yearly distribution of PAHs in the snow from the Hailuogou glacier of Mountain Gongga,China

Snow samples were collected over a 3-year period from 2012 to 2014 at the Hailuogou glacier of Mountain Gongga (Mt. Gongga) and analyzed for 16 priority polycyclic aromatic hydrocarbons (PAHs) using Gas Chromatography–Mass Spectrometry (GC–MS). The results show that total average levels of the 16 PAHs ranged from 452 to 290 ng·L^?1 with a possible declining trend from 2012 to 2014. Distances between the sampling sites and the emission sources were estimated at typically less than 500 km. The results suggest that the major source of PAHs was from coal combustion, while contributions from automobile exhaust played an important role in more recent years. This finding was in agreement with the characteristics of presence of local industry, residence, and recent development of tourism of the surrounding areas.     

Determination of allowable subgrade frost heave with the pavement roughness index in numerical analysis

Frost heave is an upward swelling of soil during cryogenic conditions in cold regions. It is caused by the accumulation of ice crystals in subgrade soil, which grow upwards when freezing temperatures penetrate into the subgrade. This study establishes the allowable soil subgrade frost heave based on the roughness standard of asphalt pavement in China, and aims to balance the pavement design and frost heave resistance of subgrades in cold regions. We formulated a mechanical model of pavement supported by the boundary conditions of differential frost heave, based on the elastic layered system theory. The differential soil subgrade frost heave was modeled as a sinusoidal function, and the allowable frost heave and the roughness index were modeled as the displacement boundaries for the top and bottom of the pavement structure. Then the allowable frost heave was back-calculated according to the roughness standard. Numerical results show that the allowable frost heave depends on the pavement structure, material properties, the highway grade, and other factors. In order to ensure that the actual soil subgrade frost heave is lower than the allowable frost heave, pavement structures and materials need to be selected and designed carefully. The numerical method proposed here can be applied to establish the frost heave resistance of subgrade when the pavement structure and materials are determined.     

历史文献中气候信息的评价

本文对我国史料中所载气候信息进行了评价。结论是:①对于史料所载的某一气候事件,我们将其状态分辨取越细,所获取的信息越少;②在分析过程中,对误差要求低些,所获取的信息反而高些;③就已记录的气候事件而言,官方组织的记载所提供的气候信息最多,私人笔札次之,方志类书最次。     

干旱地区灌丛沙堆研究现状与展望

从灌丛沙堆的形成演变、形态特征及其空间格局、表面气流特征及其风蚀堆积平衡、表面植被生态生理特性及其对降水和地下水的响应、土壤理化性质和保育措施等几个方面进行综述。认为目前灌丛沙堆研究只是针对某一区域或多个区域的静态研究,对灌丛沙堆演化过程中的形态、气流、土壤以及植被等因素的变化特征及其相互作用研究不足,难以解释灌丛沙堆的演化机制及其影响因素。同时灌丛沙堆研究过于强调其作为土地退化的指示,而忽略了其在退化生态系统中的重要生态功能,不利于干旱和半干旱区的生态环境恢复。今后的研究应该加强对灌丛沙堆演化过程中的土壤、植被、水分的变化特征及其不同影响因素之间相互作用过程的研究,深入探讨灌丛沙堆在干旱半干旱退化生态系统中的积极作用。基于以上基础数据和理论依据,对灌丛沙堆的保育措施进行探索,找出合理的灌丛沙堆保育措施。