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11.
下扬子区石炭系老虎洞白云岩的形成认为是被蒸发泵吸作用稍加改变的浅淡含水层与海水混合白云岩化的结果,并特别强调准同生期灰泥潮坪受蒸发泵吸作用形成的白云石籽晶在混合白云岩化中的动力学作用;其上“粗晶灰岩”的形成则是经历了白云化——溶解——菱面体孔隙形成及其相互连接——地下缝洞层的形成——粗晶方解石在缝洞空间自由生长——垮塌——再胶结的复杂过程。 相似文献
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Changes in enantiomeric fraction as evidence of natural attenuation of mecoprop in a limestone aquifer 总被引:1,自引:0,他引:1
Natural attenuation of the chiral pesticide mecoprop [2-(2-methyl-4-chlorophenoxy)propionic acid] has been studied by determining changes in its enantiomeric fraction in different redox environments down gradient of a landfill in the Lincolnshire Limestone. Previous studies have shown that mecoprop degrades predominantly aerobically and that differences in the biological behaviour of the two enantiomers will change their relative proportions during biodegradation. Originally deposited as a racemic mixture, there has been no change in the enantiomeric fraction in the most polluted part of the landfill plume where conditions are sulphate reducing/methanogenic. In the nitrate-reducing zone, the proportion of (S)-mecoprop increases, suggesting preferential degradation of (R)-mecoprop; while in the aerobic zone, the proportion of (R)-mecoprop increases, suggesting faster degradation of (S)-mecoprop. Mecoprop persistence in the confined Lincolnshire Limestone further downdip is explained by inhibition of degradation in sulphate-reducing conditions, which develop naturally. Laboratory microcosm experiments using up to 10 mg l(-1) of mecoprop confirm these inferences and show that under aerobic conditions, (S)-mecoprop and (R)-mecoprop degrade with zero-order kinetics at rates of 1.90 and 1.32 mg l(-1) day(-1), respectively. Under nitrate-reducing conditions (S)-mecoprop does not degrade, but (R)-mecoprop degrades with zero-order kinetics at 0.65 mg l(-1) day(-1) to produce a stoichiometric equivalent amount of 4-chloro-2-methylphenol. This metabolite only degrades when the (R)-mecoprop has disappeared. The addition of nitrate to a dormant iron-reducing microcosm devoid of nitrate stimulated anaerobic degradation of (R)-mecoprop after a lag period of 21 days. There was no evidence for enantiomeric inversion. The study demonstrates the sensitivity of changes in enantiomeric fraction for detecting natural attenuation, and reveals subtle differences in mecoprop degradation in different redox environments within the Lincolnshire Limestone aquifer. 相似文献
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本文以江英乡为例,阐明了广东石灰岩山区土壤资源的生态环境特点。针对这些特点,我们提出了顺应生态环境、充分发挥小气候优势、推广良种良法、调整农业结构、发展外向型绿色企业以及保水保土等一系列综合开发利用的措施,并在江英乡付诸实施。实践证明,这些措施具有明显的经济效益和社会效益,从而为广东石灰岩山区开发利用土壤资源、发展农业经济提供了参考依据。 相似文献
14.
Pongdhorn Sae-oui Chakrit Sirisinha Puchong Thaptong 《Journal of Material Cycles and Waste Management》2009,11(2):166-171
The possibility of using limestone dust waste (LDW) as a filler in natural rubber (NR) was investigated. First, the basic
properties of LDW were characterized; LDW was then incorporated into NR and the compound properties were determined. Comparison
of the reinforcing effect of LDW and other commercial fillers such as light-precipitated calcium carbonate (PCC) and nanoprecipitated
calcium carbonate (NPCC) was made. The results revealed that even though the addition of LDW has little effect on compound
processability, it has a negative effect on most mechanical properties, e.g., tensile strength, tear strength, and abrasion
resistance, of the vulcanizate. Among the three fillers, the degree of reinforcement could be placed in the following order:
NPCC > PCC > LDW. Due to their relatively low specific surface area and thus low reinforcement ability, both LDW and PCC can
be grouped as nonreinforcing fillers, whereas NPCC, the specific surface area of which is relatively high, could be grouped
as a semi-reinforcing filler for rubber. 相似文献
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为了解决煤矿灰岩水铁含量高,较难复用的问题,进行了接触过滤氧化法处理模拟含铁原水的试验研究。结果表明:采用石英砂滤料的接触过滤氧化工艺处理铁含量为2.0mg/L的模拟原水除铁效果明显,当气水比为2.0,pH值为7.5~8.0,停留时间小于2~3min,滤速为12.0m/h时,除铁率可达90%以上,滤后水满足铁含量0.3mg/L的井下复用水质要求,且过滤周期长达36h;同时分析得出最大平均催化氧化速率系数为KFe2+=1.50×1011L3mg-3s-1和除铁拟合曲线方程-Ln(Ct/Co)=-0.0011x2+0.0517x+1.748。 相似文献
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以林华煤矿为例,运用FLAC3D软件对林华煤矿开采13#煤层进行模拟,在模拟中通过开采对底板的破坏情况进行分析,对林华煤矿开采13#煤层底板是否有突水危险性进行预测研究。 相似文献
19.
温度、SO_2浓度、颗粒大小、石灰石类型和样品的微观结构影响着直接硫酸化反应过程。这一反应过程能用缩芯模型来描述,并对SO_2具有一级反应特征。本征反应和产物层扩散控制反应的活化能分别是85.2kJ/mol和41.5kJ/mol。在800℃、2000ppmSO_2和反应101min的条件下,Igzlaberga和Forsby石灰石的CaCO_3转化率分别可达84%和72%。在初始2min内已煅烧石灰石(CaO)的硫酸化反应速率与石灰石的反应速率稍高,随后二者基本相同。 相似文献
20.
Krishna Murari 《Resources Policy》1984,10(1):52-63
Most of the two billion tonnes of limestone consumed annually is used either as the basic raw material in the manufacture of cement or as flux input in the metallurgical industries. Of the total flux, 90% is used by the steel industry. The cement industry needs limestone in a finely pulverized form, whereas the steel industry uses it in lump form, with the lumps not less than 12 mm in size. The exploitation of limestone as flux for the steel industry must be scientifically planned. This article covers the methodology of planning, incorporating the study of the detailed status of the resource inventory, demand for limestone, exploration of new deposits, and calculating and manipulating the costs of production, transport and development of each project to match the demand pattern of steel plants. A computer was used for the optimization of supplies and their selection on planning horizons. 相似文献