水热蚀变分带和矿物-水化的反应动力学过程

笔者重点介绍在22 MPa、在25～400℃范围的钠长石在水和KCI溶液里溶解反应动力学实验结果.并试图应用这一实验结果解释水热蚀变的形成机制。钠长石与水溶液反应动力学实验是在开放体系的流动反应器(叠层反应器)里进行的。钠长石在水中的溶解反应经常是不一致溶解作用,只在近水临界点(374℃)的300℃出现一致溶解过程。由25～300℃。

Heavy metal contamination, physico-chemical and microbial evaluation of water samples collected from chromite mine environment of Sukinda, India

Water samples from chromite mine quarry of Sukinda and its adjacent areas were analyzed for their heavy metal contamination along with physico-chemical and microbial contents. The chromite mine water samples possessed high concentrations of heavy metals in the order of Cr〉Fe〉Zn〉Ni〉Co〉Mn while ground water did not show any heavy metal contamination except Fe. Physico-chemical parameters of mine water samples showed deviation from those of normal water. Mine water harboured low microbial populations of bacteria, fungi and actinomycetes in comparison with mine adjacent water samples. The correlation of data between metals with physico-chemical parameters showed both positive and negative responses while that of metal and microbial population exhibited negative correlation. Bacterial strains isolated from chromite mine water exhibited high tolerance towards chromium and other heavy metals as well as antibiotics which could be used as an indicator of heavy metal pollution.

A hydrochemical study of the Hammam Righa geothermal waters in north-central Algeria

This study focuses on the hydrochemical characteristics of 47 water samples collected from thermal and cold springs that emerge from the Hammam Righa geothermal field, located in north-central Algeria. The aquifer that feeds these springs is mainly situated in the deeply fractured Jurassic limestone and dolomite of the Zaccar Mount. Measured discharge temperatures of the cold waters range from 16.0 to 26.5 ℃ and the hot waters from 32.1 to 68.2 ℃. All waters exhibited a near-neutral pH of 6.0-7.6. The thermal waters had a high total dis- solved solids （TDS） content of up to 2527 mg/l, while the TDS for cold waters was 659.0-852.0 mg/l. Chemical analyses suggest that two main types of water exist： hot waters in the upflow area of the Ca-Na-SO4 type （Ham- mam Righa） and cold waters in the recharge zone of the Ca-Na-HCO3 type （Zaccar Mount）. Reservoir tempera- tures were estimated using silica geothermometers and fluid/mineral equilibria at 78, 92, and 95℃ for HR4, HR2, and HRI, respectively. Stable isotopic analyses of the δ18O and δD composition of the waters suggest that the thermal waters of Hammam Righa are of meteoric origin. We conclude that meteoric recharge infiltrates through the fractured dolomitic limestones of the Zaccar Mount and is conductively heated at a depth of 2.1-2.2 km. The hotwaters then interact at depth with Triassic evaporites located in the hydrothermal conduit （fault）, giving rise to the Ca-Na-SO4 water type. As they ascend to the surface, the thermal waters mix with shallower Mg-rich ground- water, resulting in waters that plot in the immature water field in the Na-K-Mg diagram. The mixing trend between cold groundwaters from the recharge zone area （Zaccar Mount） and hot waters in the upflow area （Hammam Righa） is apparent via a chloride-enthalpy diagram that shows a mixing ratio of 22.6 〈 R 〈 29.2 %. We summa- rize these results with a geothermal conceptual model of the Hammam Righa geothermal field.

Physico-chemical Characteristics of a Gold Mining Tailings Dam Wastewater

The study was conducted on the status of the quality of wastewater from the tailings dam of Central Africa Gold Limited in Bibiani, Ghana, to ascertain the level of contamination of the wastewater. The tailings dam stores process effluent from the gold extraction plant. Wastewater samples taken from the tailings dam were analyzed for physico-chemical characteristics. Arsenic, iron and cyanide were identified as the major pollutants in the tailings dam wastewater with average concentrations of 4.5, 25.2 and 11.1 mg.L1, respectively. Arsenic, iron and free CN （cyanide） concentrations in the process effluent exceeded the Ghana EPA discharge limits of 0.2, 2 and 0.2 mg.Ll, respectively. High conductivity, total dissolved solids, sulphate and ammonium were found in the wastewater studied. The tailings dam serves as a natural reservoir that removes most of the total suspended solids and the turbidity, resulting in the improvement in the aesthetic appeal of the wastewater. Nonetheless, arsenic, iron and cyanide concentrations were still high and hence the wastewater cannot be discharged into the environment without prior treatment.

Effect of Using Magnetic Brackish Water on Irrigated Bell Pepper Crop （Capsicum annuum L.） Characteristics in Lower Jordan Valley/West Bank

Increasing salinity of the groundwater is one of major challenges faced by agricultural sector in West Bank/Palestine. This study was carried out in the Lower Jordan Valley （LJV） under greenhouse field condition, where an area of 0.12 ha was irrigated with 3.5 dS/m magnetic treated water during the growing season 2012/2013. The results of this pilot project show that there are significant increases in the yield of red and yellow bell pepper of about 20% and 18% on fresh weight basis, respectively. Water use efficiency increased by 15% and an increase in shelf time of 7 d were also recorded. The chlorophyll content raised significantly in the leaves of treated plants compared to the controlled one by 2.5 mg/g. Bell pepper irrigated with magnetic water produces 37% more four champers than that of the controlled one. On the other hand, there were no clear significant effects on the height of the plant, number of fruits, distance between nods, size of fruits, number and thickness of walls and sugar contents. Applying visible/near infrared （VIS/N｜R） spectroscopy test shows that it is possible to distinguish between treated and controlled bell pepper fruits. Multivariate data analysis （MVDA） method was used to test the classification of chemical elements in the fruit and it was found that treated and controlled fruit samples are divided into two groups according to their water treatment. An increase in all nutrient concentrations was found in fruits irrigated with magnetic treated water compared with the controlled one. Further testing is needed especially by involving other variables such as decreasing the volume of irrigated water and fertilizers.

Relation of Mineralizable N to Organic N Components in Dark Loessial Soils

Mineralizable N and organic N components in different layers (0～15, 15～30,30～45, 45～60, 60～80 and 80～100 cm) of six soils with different fertilities sampled from YongshouCounty, Shaanxi Province, China, were determined by the aerobic incubation method and the Bremnerprocedure, respectively. Correlation, multiple regression and path analyses were performed to studythe relation of mineralizable N to organic N components. Results of correlation and regressionanalyses showed that the amounts of the N mineralized were parallel to, and significantly correlatedwith, the total acid hydrolyzable N, but was not so with the acid-insoluble N. Of the hydrolyzableN, the amino acid N and the ammonia N had a highly consistent significant correlation with themineralized N, and their partial regression coefficients were significant in the regressionequations, showing their importance in contribution to the mineralizable N. The amino sugar N, onthe other hand, had a relatively high correlation with the mineralized N, but their partialregression coefficients were not significant in the regression equations. In contrast, thehydrolyzable unknown N had no such relations. Path analysis further indicated that the amino acid Nand ammonia N made great direct contributions to the mineralized N, but the contributions of theamino sugar N were very low. These strongly suggested that the mineralized N in the soils tested wasmainly from the hydrolyzable N, particularly the amino acid N and ammonia N which are the majorsources for its production.

Heavy Metals in a Sulfldic Minespoil: Fractions and Column Leaching

Fractions of various heavy metals in a sulfidic minespoil were investigated. Column leaching experimentwas also conducted to simulate 'acid mine drainage' (AMD) from the minespoil. The results show thatleaching of heavy metals from the minespoil was extremely significant during the initial water flushing.The amounts of heavy metals leached out dramatically reduced after leaching twice. It is worthwhile tonote that in this study, Zn, Mn, Fe, As and Ni in the first leachate exceeded the total amount of eachcorresponding water-extractable (1:5, soil:water) metal contained in the minespoil sample. This appears tosuggest that 1:5 water extraction did not allow accurate estimation of water-leachable concentrations of theabove heavy metals. This work has implications for the management of sulfidic minespoils. Acid drainageof great environmental concerns is likely to occur only during heavy rainfall events after substantial solubleand readily exchangeable acid and metals are accumulated in the minespoils. The slow-reacting fractionsother than water-soluble and readily exchangeable fractions may pose little environmental hazards. This isparticularly true for Pb, As and Ni.

Technogenic hydrogeochemical anomalies of tungsten deposits in Kykylbey ore region

Peculiarities of the tungsten deposits drainage flow chemical composition formation, the development of which was ceased almost 40 years ago, have been considered. Migration peculiarities of ore components have been covered, and forms of their migration have been calculated. Inertial characteristics of the surface flow contamination are shown.

Acidophilic bacterial community reflecting pollution level of sulphide mine impacted by acid mine drainage

To reveal the impact of mining on bacterial ecology around mining area,bacterial community and geochemical characteristics about Dabaoshan Mine(Guangdong Province,China)were studied.By amplified ribosomal DNA restriction analysis and phylogenetic analysis,it is found that mining pollution greatly impacts the bacterial ecology and makes the habitat type of polluted environments close to acid mine drainage(AMD)ecology.The polluted environment is acidified so greatly that neutrophil and alkaliphilic microbes are massively dead and decomposed.It provided organic matters that can make Acidiphilium sp.rapidly grow and become the most bacterial species in this niche.Furthermore,Acidithiobacillus ferrooxidans and Leptospirillum sp.are also present in this niche.The amount of Leptospirillum sp.is far more than that of Acidithiobacillus ferrooxidans,which indicates that the concentration of toxic ions is very high.The conclusions of biogeochemical analysis and microbiological monitor are identical. Moreover,because the growth of Acidithiobacillus ferrooxidans and Leptospirillum sp.depends on ferrous iron or inorganic redox sulfur compounds which can be supplied by continual AMD,their presence indicates that AMD still flows into the site.And the area is closer to the outfalls of AMD,their biomasses would be more.So the distinction of their biomasses among different areas can help us to find the effluent route of AMD.

Clay mineral expansion of black cotton soil based on interlayer cation hydration

To analyze the water swelling characteristics of black cotton soil(BCS),X-ray fluorescence and X-ray diffraction characterizations were performed to investigate the chemical compositions and types of clay minerals in BCS.A montmorillonite crystal lattice was established to simulate the hydration of interlayer cations by applying the SPC/E potential energy model,universal force field,algorithm of charge balance,and periodic boundary.Results indicated that the main clay mineral found in the BCS was montmorillonite(32.6%)with small amounts of interstratified illite-montmorillonite(10.9%),illite(2.3%),and kaolinite(1.5%).The high expansive potential of BCS comes from the strong adsorption property of montmorillonite with a high content of magnesium and sodium ions to water molecules.The exchangeable cations of Na^(+)in BCS were only 3.73%,but they enhanced the adsorption capacity of clay to water molecules and accelerated the hydration of Mg^(2+)(47.1%)and Ca^(2+)(4.78%).The free swell index can be used as a classification index of the swelling potential of BCS.

Deterioration of Concrete by the Oxidation of Sulphide Minerals in the Aggregate

Cases of degradation of concrete associated to iron sulphides in aggregates were recently recognized in the Trois-Rivi6res area, Canada. The aggregate used to produce concrete was an anorthositic gabbro containing various proportions of pyrite, pyrrhotite, chalcopyrite and pentlandite. Quantitative microanalysis on sulphide minerals show that pyrrhotite contains small amount of Ni, Co, Cu and As substituting for Fe in the mineral structure. Considering element substitution, x value in the chemical formula （Fe~.xS） was calculated to 0.099 in the pyrrhotite studied. Petrographic examination of damaged concretes showed the presence of oxidized pyrrhotite. The observation of polished samples shows, in several cases, that the pyrite is intact while the pyrrhotite presents evident signs of oxidation. In the presence of water and oxygen, pyrrhotite oxidizes to form iron oxyhydroxides and sulphuric acid. The acid then reacts with the phases of the cement paste and provokes the formation of gypsum and ettringite. These minerals were observed by SEM-EDS （scanning electron microscope/energy dispersive x-ray spectrometer） and their precipitation causes a volume increase that creates expansion and cracking of the concrete.

Particle Size Distribution of Kaolinite and Halloysite in Weathering Products of Granite and Its Implications for Pedogenesis

The kaolins collected from a profile of weathered granite at Yichun County, Jiangxi Province have been subjected to particle size fractionation by the conventional sedimentation method and examined by XRD,SEM and TEM. All of them exhibit a mixture phase of poorly crystallized kaolinites and halloysites (0.7 nm) occurring as the main clay minerals. Electron micrographs reveal that plate kaolinites are the principal constitution in the coarse fraction, and more tubular and curled halloysite (0.7 nm) in the fine fraction. Both of them show normal probability curves in particle size distributions. The ratios of kaolinite and halloysite (0.7 nm) in different size fractions are examined by X-ray diffraction with a series of X-ray patterns characterized by three main peaks at d(001), d(002) and d(020),varying in intensity. Therefore, an index Qhm, expressed as (Id(001) + Id(002))/(2×Id(020)), is designed to indicate relative ratios of the two clay minerals in a number of mixture phases. Because kaolinite and halloysite (0.7nm) commonly occurred, respectively, in low and medium leaching microenvironment, the index Qhm can be used to indicate weathering and pedogenic.conditions of a weathering crust.

Short-Term Responses of Nitrogen Mineralization and Microbial Community to Moisture Regimes in Greenhouse Vegetable Soils

Soil drying and wetting impose significant influences on soil nitrogen (N) dynamics and microbial communities. However, effects of drying-wetting cycles, while common in vegetable soils, especially under greenhouse conditions, have not been well studied. In this study, two greenhouse vegetable soils, which were collected from Xinji (XJ) and Hangzhou (HZ), China, were maintained at 30% and 75% water-holding capacity (WHC), or five cycles of 75% WHC followed by a 7-day dry-down to 30% WHC (DW). Soil inorganic N content increased during incubation. Net N mineralization (Nmin), microbial activity, and microbial biomass were significantly higher in the DW treatment than in the 30% and 75% WHC treatments. The higher water content (75% WHC) treatment had higher Nmin, microbial activity, and microbial biomass than the lower water content treatment (30% WHC). Multivariate analyses of community-level physiological profile (CLPP) and phospholipid fatty acid (PLFA) data indicated that soil moisture regime had a significant effect on soil microbial community substrate utilization pattern and microbial community composition. The significant positive correlation between Nmin and microbial substrate utilization or PLFAs suggested that soil N mineralization had a close relationship with microbial community.

Biochar:An Emerging Panacea for Remediation of Soil Contaminants from Mining,Industry and Sewage Wastes

Mine tailings, waste rock piles, acid mine drainage, industrial wastewater, and sewage sludge have contaminated a vast area of cultivable and fallow lands, with a consequence of deterioration of soil and water quality and watercourses due to the erosion of contaminated soils for absence of vegetative cover. High concentrations of toxic elements, organic contaminants, acidic soils, and harsh climatic conditions have made it difficult to re-establish vegetation and produce crops there. Recently, a significant body of work has focussed on the suitability and potentiality of biochar as a soil remediation tool that increases seed emergence, soil and crop productivity, above ground biomass, and vegetation cover on mine tailings, waste rock piles, and industrial and sewage waste- contaminated soils by increasing soil nutrients and water-holding capacity, amelioration of soil acidity, and stimulation of microbial diversity and functions. This review addresses： i） the functional properties of biochar, and microbial cycling of nutrients in soil; ii） bioremediation, especially phytoremediation of mine railings, industrial waste, sewage sludge, and contaminated soil using biochar; iii） impact of biochar on reduction of acid production, acid mine drainage treatment, and geochemical dynamics in mine railings; and iv） treatment of metal and organic contaminants in soils using biochar, and restoration of degraded land.

Effect of hydration on the elasticity of mantle minerals and its geophysical implications

Recent studies have shown that major nominally anhydrous minerals in the Earth's mantle, such as olivine, pyroxene and garnet, can incorporate considerable amounts of water as structurally bound hydroxyl. Even a small amount of water is present in mantle minerals, it can strongly affect a number of physical properties, including density, sound velocity, melting temperature, and electrical conductivities. The presence of water can also influence the dynamic behavior, lead to lateral velocity heterogeneities, and affect the material circulation of the Earth's deep interior. In particular, seismic studies have reported the existence of low-velocity zones in various locations of the Earth's upper mantle and transition zone, which has been expected to be associated with the presence of water in the region. In the past two decades, the effect of water on the elasticity and sound velocities of minerals at relevant pressure-temperature(P-T) conditions of the Earth's mantle attracted extensive interests. Combining the high P-T experimental and theoretical mineralogical results with seismic observations provides crucial constraints on the distribution of water in the Earth's mantle. In this study, we summarize recent experimental and theoretical mineral physics results on how water affects the elasticity and sound velocity of nominally anhydrous minerals in the Earth's mantle, which aims to provide new insights into the effect of hydration on the density and velocity profile of the Earth's mantle, which are of particular importance in understanding of water distribution in the region.

CO_2 Sequestration from flue gas by direct aqueous mineral carbonation of wollastonite

Emission of carbon dioxide is considered to be the main cause of the greenhouse effect. Mineral carbonation, an important part of the CCS technology, is an attractive option for long-term CO2 sequestration. In this study, wollastonite was chosen as the feedstock and the feasibility of direct aqueous mineral carbonation in the simulated flue gas was investigated via a series of experimental studies carried in a stirred reactor. X-ray diffraction （XRD）, X-ray fluorescence spectroscopy （XRF）, ion chro- matography （IC） and thermal decomposition were used to determine the carbonation conversion. The influences of various factors, including reaction temperature, reaction pressure, solution composition, heat-treatment and particle size, were dis- cussed. Concurrently, the effects of SO2 and NO presented in simulated flue gas were also investigated and a possible mecha- nism was used to explain the results. Experimental results show that reaction temperature, reaction pressure and particle size can effectively improve the carbonation reaction. Addition of 0.6 M NaHCO3 was also proved to be beneficial to the reaction and heat-treatment is not needed for wollastonite to get a higher carbonation conversion. Compared with carbonation in puri- fied CO2 gas, CO2 sequestration directly from simulated flue gas by mineral carbonation is suggested to have a certain degree of economic feasibility in the conditions of medium and low-pressure. A highest carbonation conversion of 35.9% is gained on the condition of T=150℃, P=40 bar and PS 〈30 μ in distilled water for 1 h.