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101.
Water samples taken at 19 locations in the Mawheraiti River catchment at weekly intervals during 1979–80 were analysed for sodium, magnesium, potassium, calcium, phosphate, nitrate, and ammonium ion concentrations and for electrical conductivity. Seasonal discharge effects were apparent, and lithology and land management practice also influenced solute concentrations. Solute concentrations were generally very low; nitrate and soluble phosphate were rarely greater than 0.05 mg.L‐1 and ammonium was rarely greater than 0.01 mg.L‐1. The 4 major cations (Na, Mg, K, and Ca) usually summed to less than 6 mg.L‐1 much of which was supplied by precipitation. Forest management (clearfelling and slash‐burning) caused significant increases in solute concentrations, but concentrations declined rapidly during succeeding months and approached pretreatment levels after 2–3 years. The higher concentrations associated with forest management in small experimental catchments were rapidly diluted downstream; together with the low natural solute concentrations this suggests that harmful downstream effects of management practices are unlikely under low flow conditions. 相似文献
102.
Jijian Lian Hongyin Xu Xiaoqing He Dengfeng Fu Shuwang Yan 《Marine Georesources & Geotechnology》2013,31(2):212-222
ABSTRACTBiogrouting, which is a new method for soil improvement, was used in an attempt to cement a type of hydraulic fill fine sands (called black sands) in reclamation projects in Tianjin, China, to form a working layer for mechanical equipment. Several factors influencing biogrouting with regard to cementing solution, including injection frequency, reaction time, concentration, and flow rate, were controlled to prepare black sand columns. This paper reports on an investigation of bacterial fixation, calcium ion utilization, and calcium carbonate distributions of biogrouted sand specimens. At the end of the tests, the geotechnical performances of the sand specimens were determined. The results showed that the biogrouting method effectively solidified black sands, by increasing the unconfined compressive strength of a sand column to 1.91?MPa and reducing the permeability coefficient by three orders of magnitude. A relationship between the unconfined compressive strengths and calcium carbonate contents was put forward, in addition to a relationship between the permeability coefficients and the calcium carbonate contents. According to the experimental results, some reasonable suggestions regarding the application of biogrouting to the consolidation of hydraulic fill fine sands in reclamation projects were proposed. 相似文献
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104.
A slightly acidic hot spring named "Female Tower"(t=73.5°C, pH=6.64) is located in the Jifei Geothermal Field, Yunnan Province, southwestern China. The precipitates in the hot spring are composed of large amounts of calcite, aragonite and sulfur. Scanning electron microscopy(SEM) analyses reveal that the microbial mats were formed from various coccoid or rod-shaped filamentous microbes. Transmission electron microscopy(TEM) shows that the intracellular sulfur granules are commonly associated with these microbes. A culture-independent molecular phylogenetic analysis demonstrates that the majority of the bacteria in the spring are sulfur-oxidizing bacteria. In the spring water, H_2S concentration is up to 60 ppm, while SO_4~(2-) concentration is only about 10 ppm. We speculate that H_2S might derive from sulfur-oxidizing bacteria in this hot spring water, leading to the intracellular formation of sulfur granules. Meanwhile, this reaction increased the p H in the micronscale microdomains, which fosters the precipitation of calcium carbonate in the microbial mats. The results of this study indicate that the sulfur-oxidizing bacteria might play an important role in calcium carbonate precipitation in slightly acidic hot spring environments. 相似文献
105.
Lan‐ping Feng Lian Zhou Lu Yang Donald J. DePaolo Shuo‐Yun Tong Yong‐Sheng Liu Thomas L. Owens Shan Gao 《Geostandards and Geoanalytical Research》2017,41(1):93-106
Calcium isotopic compositions of sixteen Ca‐bearing USGS geological reference materials including igneous and sedimentary rocks are reported. Calcium isotopic compositions were determined in two laboratories (GPMR, State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan; and CIG, Centre for Isotope Geochemistry, University of California, Berkeley) using the 42Ca‐48Ca double‐spike technique by thermal ionisation mass spectrometry. As opposed to common cation exchange resin, a micro‐column filled with Ca‐selective resin (DGA resin) was used in order to achieve high recovery (> 96%) and efficient separation of Ca from the sample matrix. The intermediate measurement precision was evaluated at 0.14‰ (2s) for δ44/40CaSRM915a at GPMR, based on replicate measurements of pure Ca reference material NIST SRM 915a, NIST SRM 915b and seawater. Overall, the measurement uncertainties in both laboratories were better than 0.15‰ at the 2s level. Result validation was carried out for all available data sets. The Ca isotopic compositions of USGS reference materials are not only in agreement between GPMR and CIG, but also in agreement with previously published data within quoted uncertainties. The comprehensive data set reported in this study serves as a reference for both quality assurance and interlaboratory comparison of high precision Ca isotopic study. 相似文献
106.
在工程用土资源越来越紧张和环境日益恶化的情况下淤泥资源化利用成为一个亟待解决的问题。通过向河底淤泥中掺入一定量的生石灰,再用真空预压结合外加剂木质素磺酸钙来改善土体的渗透、强度和变形等特性,总结并分析了掺木量对稳定排水量,稳定沉降量、强度、孔隙等的影响以及真空预压后石灰稳定土龄期下土体强度的变化规律。试验结果表明,抽真空后改良土具有较低含水率,土体强度增长较大,孔隙较小,后期沉降较小,加固土体以满足填筑用土要求,经济性分析表明该法是可以接受的。 相似文献
107.
108.
石英和碳酸钙表面位的FDIR谱学研究 总被引:1,自引:0,他引:1
本文采用漫反射红外光谱(FDIR)方法对石英、方解石、合成碳酸钙和孔雀石等矿物表面位(基团)作了研究。随着溶液pH值的升高,由于表面基团间氢键的影响,石英表面位〉Si-O和〉Si-O-Si的吸收峰向高频方向漂移,即〉Si-O非对称伸缩振动吸收峰由1036cm^-1→1045cm^-1→1047cm^-1,〉Si-O-Si对称伸缩振动吸收峰由777cm^-1→782cm^-1→788cm^-1,而〈 相似文献
109.
110.
煤系高岭土合成4A沸石试验研究 总被引:14,自引:1,他引:13
本试验所用原料为大同怀仁和徐州夹河煤系高岭土,这两种原料的SiO2和Al2O3分子比均接近于2,其成分能满足合成4A沸石的要求。本试验首先进行了原料的焙烧活化及漂白的试验研究,解决了原料的白度问题。分析探讨了合成4A沸石过程中成分、碱度、温度、时间及搅拌等对合成试验的影响,并通过对比试验获得了最佳合成条件,得到了合格的4A沸石产品。 相似文献