石膏及其热转变产物的红外光谱   总被引：5，自引：0，他引：5  

彭文世  刘高魁 《矿物学报》1991,11(1):27-32

本文给出了石膏及其热转变产物－－烧石膏和硬石膏的红外光谱。在晶体结构资料基础上，对石膏和硬石膏分别进行了因子群分析和位置群分析，其结果清楚地表明，理论预测的光谱与实测光谱相当一致。根据烧石膏的红外光谱和位置群分析的结果可以肯定。SO4^2-离子的位置对称性不可能是D 2，只能为C2或C1。热转变产物的红外光谱表明，石膏－－烧石膏和烧石膏－硬石膏之间的热转变温度分别为80－100℃和350－400℃。  相似文献   

Sodium sulphate weathering and the disintegration of Mohenjo-Daro,Pakistan     

A. S. Goudie 《地球表面变化过程与地形》1977,2(1):75-86

In Pakistan various brick building structures are currently disintegrating in the Indus Valley. These include the Harappan site of Mohenjo-Daro. The environment of this site is described, the nature and speed of the disintegration problem is outlined, and the cause of disintegration is discussed Weathering occurs in association with the development of salt efflorescences and some bricks disintegrate only a few years after being laid down. Chemical and X-ray diffraction analyses show that the predominant salt is the sodium sulphate mineral thenardite. The reasons for its effectiveness are discussed. They include its high solubility, the rapid change of solubility with temperature, and its hydration characteristics.  相似文献   

激光探针稳定同位素分析技术的现状及发展前景   总被引：8，自引：0，他引：8  

张凤娥  卢耀如  郭秀红  刘广联 《地学前缘》2003,10(2):0-0

以揭示碳酸盐岩和硫酸盐岩相伴沉积时发生的复合岩溶形成机制为目的 ,采用室内模拟实验方法 ,利用反应路径模型研究了水流路径上碳酸盐岩→硫酸盐岩 (简称层序 1)和硫酸盐岩→碳酸盐岩 (简称层序 2 )两种层序时发生的地球化学作用 ,根据质量平衡原理 ,计算了水岩间发生的地球化学作用强度 ;探讨了硫酸盐岩成因、岩溶发育的环境温度对复合岩溶的影响。结果表明 ,复合岩溶形成机理与可溶岩层序关系密切 ,层序 1中 ,发生两种可溶岩的溶解作用 ;层序 2中 ,除硫酸盐岩 (石膏和半水石膏 )溶解外 ,碳酸盐岩 (白云岩 )发生的是去白云化作用。这些作用间通过不同的机制相互促进 ,导致复合岩溶较单一可溶岩的岩溶更发育。复合岩溶的发育程度还受溶液 pH值和环境温度影响 ,溶液pH值降低、环境温度升高都利于复合岩溶发育。  相似文献   

Aqueous Phase Reaction of HNO4: The Impact on Tropospheric Chemistry     

Frank Dentener  Jason Williams  Swen Metzger 《Journal of Atmospheric Chemistry》2002,41(2):109-133

We use a global atmospheric chemistry transport model to study the possible influence of aqueous phase reactions of peroxynitric acid (HNO₄) on the concentrations and budgets of NO_x, SO_x, O₃ and H₂O₂. Laboratory studies have shown that the aqueous reaction of HNO_4aq withHSO^– _3aq, and the uni-molecular decomposition of the NO₄ ^– anion to form NO₂ ^– (nitrite) occur on a time scale of about a second. Despite a substantial contribution of the reaction of HSO^– _3aq with HNO_4aq to the overall in-cloud conversion of SO₂ to SO₄ ^2–, a simultaneous decrease of other oxidants (most notably H₂O₂) more than compensated the increase in SO₄ ^2– production. The strongest influence of heterogeneous HNO₄ chemistry was found in the boundary layer, where calculated monthly average ozone concentrations were reduced between 2% to 10% andchanges of H₂O₂ between –20% to +10%compared to a simulation which ignores this reaction. Furthermore, SO₂ was increased by 10% to 20% and SO₄ ^2–depleted by up to 10%. Since the resolution of our global model does not enable a detailed comparison with measurements in polluted regions, it is not possible to verify whether considering heterogeneous HNO₄ reactions results in a substantial improvement of atmospheric chemistry transport models. However, the conversion of HNO₄ in the aqueous phase seems to be efficient enough to warrant further laboratory investigations and more detailed model studies on this topic.  相似文献   

Freshwater macroinvertebrate distribution in two basins with different salinity gradients (Guadalete and Guadaira river basins,south-western Spain)   总被引：1，自引：0，他引：1  

Alfonso Gallardo-Mayenco 《International Journal of Salt Lake Research》1994,3(1):75-91

This work reports the results of one year's sampling of aquatic macroinver-brates in various streams with different salinity gradients. The study area was the headwaters of the rivers Guadaíra and Guadalete, located in the same geographical area in south-western Spain. The most interesting feature of the Guadaíra basin is the natural salinity of its waters due to the abundance of gypsum in its headwaters. Lithologically, the headwaters of the Guadalete basin flow over marls, clay, sandstone and limestone. Salinity values in most streams do not reach 1 mS cm^–1. At least at the levels of salinity found in the Guadaíra basin headwaters, the existence of a well-structured community of macroinvertebrates can be claimed. Of the groups studied, Diptera and Coleoptera showed the highest species richness, being distributed preferentially at the ends of the conductivity spectrum. Groups including taxa inhabiting waters of low salinty and taxa inhabiting waters with high salinity could be reliable indicators of salinity.  相似文献   

柴达木石——一种锌和铁的硫酸盐新矿物   总被引：1，自引：0，他引：1  

李万茂  陈国英  彭志忠 《矿物学报》1986,(2)

柴达木石是一种Zn和Fe~(3+)的硫酸盐新矿物,发现于我国青海省柴达木锡铁山铅锌矿氧化带。矿物属单斜晶系,空间群P2_1/m或P2_1,晶胞参数a=9.759(9)A,b=7.134(9)A,c=7.335(11)A,β=106.2(1)°,Z=2。化学分子式为ZnFe~(3+)(SO_4)_2(OH)·4H_2O。它是四水铜铁矾(guildite)的类似物。  相似文献   

The effects of acid sulphate run-off on a subtidal estuarine macrobenthic community in the Richmond River, NSW, Australia   总被引：1，自引：0，他引：1  

Corfield  Jamie 《ICES Journal of Marine Science》2000,57(5):1517-1523

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Potential use of organic waste substances as an ecological technique to reduce pesticide ground water contamination     

Hicham El Bakouri  Jos Morillo  Jos Usero  Abdelhamid Ouassini 《Journal of Hydrology》2008,353(3-4):335-342

The heavy use of pesticides in agriculture has meant that the fate due to their movement after their application continue to be a real problem for the environment. In this work, a viable eco-remediation technique based on the use of natural organic substances (NOS) that characterize the Mediterranean region is proposed to demonstrate the efficiency of endosulfan sulphate removal from water. Experimental results showed that the pH of pesticide solutions and temperature negatively affect the adsorption process. According to adsorption kinetic data, 5 h were considered as the equilibrium time for realizing adsorption isotherm. The Freundlich isotherm model describes better the adsorption process of endosulfan sulphate on NOS tested. The Freundlich constant K_f depended mainly on the nature of each adsorbent and ranged from 5.56 for straw to 13.54 for date stones. The adsorption tests gave very satisfying results and point to the possible application of these supports as an ecological remediation technique to reduce pesticide contamination of aquatic ecosystems.  相似文献   

A modelling study of aerosol processing by stratocumulus clouds and its impact on general circulation model parameterisations of cloud and aerosol     

K. N. Bower  A. Jones  T. W. Choularton   《Atmospheric Research》1999,50(3-4)

A model of the aqueous phase processing of an aerosol population undergoing multiple cycling through a stratocumulus (Sc) cloud layer is presented. Results indicate that a significant modification of the aerosol properties is achieved following the first cycle through cloud. In a polluted atmosphere, further modification in subsequent cycles is seen to be hydrogen peroxide limited unless there is a flux of ammonia entering the system through cloud base (CB). The modification of the aerosol population is seen to have little effect on the microphysics (specifically the cloud droplet concentration and effective radius) of the processing cloud. However, it enables processed aerosols to subsequently act as efficient cloud condensation nuclei (CCN) in less vigorous clouds (as a result of reducing the critical supersaturation required to activate them). The effects of variations in the internal mixture of soluble components of aerosols on the microphysics of clouds forming on them are also investigated using the cloud model. A (K2) parameterisation of the effects of variations in internally mixed nitrate loadings on the cloud droplet number concentration is presented. The effects of applying this K2 correction to the droplet number (derived from a parameterisation based on sulphate) for the presence of nitrate in aerosol have been investigated using the HadAM3 version of the Hadley Centre General Circulation Model (GCM). The effect on global annual mean simulations of the indirect forcing and effective radius is small, but more pronounced regionally. Suggestions (based on model results and observations) for parameterising the size distribution and in-cloud growth of aerosols for use in GCMs are presented.  相似文献   

Mass transport modelling for assessement of groundwater contamination around Mathura oil refinery, Mathura, Uttar Pradesh, India     

V. V. S. Gurunadha Rao  R. L. Dhar  T. Jayachand  C. S. Khoker 《Environmental Geology》2000,39(10):1138-1146

Mathura oil refinery was commissioned during 1977 and effluent storage ponds were constructed at the same time. These storage ponds receive wastewater from the refinery at a rate of 10000 m³/day. After treatment, waste water is discharged through a 3-km pipeline to a stream leading to the Yamuna river. The groundwater-monitoring as well as water-quality monitoring was carried at 24 observation wells in the refinery site during 1997. The water quality measurements indicated total dissolved chloride and sulphate concentration of native groundwater as 400 mg/l, whereas elevated levels up to 600 mg/l were found at the wells close to polishing ponds. Thus combined transport of chloride and sulphate was simulated in the mass transport model. A three-dimensional flow, pathlines and mass transport model of the aquifer system were constructed to analyze the impact of seepage from polishing ponds contaminating the groundwater regime. The permeability of aquifer varies between 1.5–2.5 m/day. The porosity of formation was assumed as 0.2. The constant head and constant concentration boundaries were assigned to the nodes representing effluent storage ponds. Longitudinal dispersivity of 100 m, horizontal transverse dispersivity of 10 m and vertical transverse dispersivity of 0.01 m were assumed. The mass transport model was calibrated for 20 years by comparing total dissolved chloride and sulphate concentrations from 1997. The model predictions indicate further migration of contaminants on the east of effluent ponds in future. Received: 4 January 1999 · Accepted: 12 July 1999  相似文献