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1.
Assessment of groundwater quality is essential to ensure sustainable use of it for drinking, agricultural, and industrial purposes. The chemical quality of groundwater of Gaya region has been studied in detail in this work to delineate the potable groundwater zones. A total of 30 groundwater samples and 2 surface water samples were collected in and around Gaya district of Bihar. The major cations follow the trend: Ca2+?>?Mg2+?>?Na+?>?K+. The domination of calcium ions in the groundwater is due to weathering of rocks. The K+ ranged between 0.2 and 47.95 ppm, suggesting its abundance the below desired limit; but some samples were found to be above permissible limit. K+ weathering of potash silicate and the use of potash fertilizer could be the source. The major anions abundance followed the order HCO 3 ? ?>?Cl??>?SO 4 2? ?>?NO 3 ? ?>?PO 4 3? . Dissolution of carbonates and reaction of silicates with carbonic acid accounts for the addition of HCO 3 ? to the groundwater and oxidation of sulphite may be the source of SO 4 2? . Principal component analysis was utilized to reflect those chemical data with the greatest correlation and seven major principal components (PCs) representing >80 % of cumulative variance were able to interpret the most information contained in the data. PC1, PC2 and PC3 reflect the hydrogeochemical processes like mineral dissolution, weathering and anthropogenic sources. PC4, PC5, PC6 and PC7 show monotonic, random and independent relationships.  相似文献   

2.
The results of a systematic analysis of master radial-velocity curves for the X-ray binary 4U 1700-37 are presented. The dependence of the mass of the X-ray component on the mass of the optical component is derived in a Roche model based on a fit of the master radial-velocity curve. The parameters of the optical star are used to estimate the mass of the compact object in three ways. The masses derived based on information about the surface gravity of the optical companion and various observational data are 2.25 ?0.24 +0.23 M⊙ and 2.14 ?0.56 +0.50 M⊙. The masses based on the radius of the optical star, 21.9R⊙, are 1.76 ?0.21 +0.20 M⊙ and 1.65 ?0.56 +0.78 M⊙. The mass of the optical component derived from the mass-luminosity relation for X-ray binaries, 27.4M⊙, yields masses for the compact object of 1.41 ?0.08 + M⊙ and 1.35 ?0.18 +0.18 M⊙.  相似文献   

3.
Study on geochemistry of groundwater occurring at different depths is rarely attempted due to inherent difficulties in sample isolation and lack of significant species variations. Three-dimensional (spatial, temporal and depth-wise) evaluation of water chemistry variations would give holistic picture of aquatic chemistry. In order to fill the knowledge gap the vertical hydrogeochemistry of Penna-Chitravati inter-stream sub-basin is studied.Water samples are segregated into different groups based on water levels of source wells. The group samples pertaining to granite terrain (A to C) does not show much variation for tested parameters as most of the samples fall within 20m water level. In shale aquifers groundwater is progressively less ionized as depth to levels increases (Group D to G). Reduction of EC and Na-Cl along with falling water levels indicates deeper aquifers are free from contamination. Gradual decrease in HCO 3 - with depth substantiates that deeper aquifers are getting less fresh water due to lack of inter connectivity in shale formations. Sodium in groundwater of both the granite and shale aquifers is contributed by weathering of silicate rocks as the Na+/Cl- molar ratio is >1 in many samples. Majority of the samples in both the geological terrains have Ca2+/Mg2+ ratio between 1 to < 2 indicating dolomite dissolution is responsible for Ca2+-Mg2+ contribution. The chemistry of tested water indicate aquifer matrix is responsible for chemical make-up of pore water which was obliterated due to extraneous sources like anthropogenic contamination as Na+, Cl-, NO 3 - and SO 4 2- /HCO 3 - is high in many samples belonging to shallow aquifers. Thermodynamic action in deep aquifers could be responsible for dissimilar water chemistry in aquifers belonging to same geological domain.  相似文献   

4.
Hydrogeochemical studies have been carried out in a coastal region, using multivariate statistical model, for better understanding the controlling processes that influence the aquifer chemistry. Two principal components (PC1 and PC2) are extracted from the data set of chemical variables (pH, TDS, Ca2+, Mg2+, Na+, K+, HCO 3 ? , Cl?, SO 4 2? , NO 3 ? and F?), which account for 79% of the total variation in the quality of groundwater. The PC1 (salinity controlled process) includes the concentrations of TDS, Mg2+, Na+, K+, Cl?, SO 4 2? and NO 3 ? , while the PC2 (alkalinity controlled process) comprises the concentrations of pH, HCO 3 ? and F?. The spatial distribution of PC scores identifies the locations of high salinity and alkalinity processes. The first process corresponds to the influences of geogenic, anthropogenic and marine sources, and the second one to the influence of water-soil-rock interaction. Thus, the present study shows the usefulness of multivariate statistical model as an effective means of interpretation of spatial controlling processes of groundwater chemistry.  相似文献   

5.
A study on the geochemistry of groundwater was carried out in a river basin of Andhra Pradesh to probe into the spatial controlling processes of groundwater contamination, using principal component analysis (PCA). The PCA transforms the chemical variables, pH, EC, Ca2+, Mg2+, Na+, K+, HCO \(_3^- \) , Cl?, SO \(_4^{2-} \) , NO \(_3^-\) and F?, into two orthogonal principal components (PC1 and PC2), accounting for 75% of the total variance of the data matrix. PC1 has high positive loadings of EC, Na+, Cl?, SO \(_4^{2-} \) , Mg2+ and Ca2+, representing a salinity controlled process of geogenic (mineral dissolution, ion exchange, and evaporation), anthropogenic (agricultural activities and domestic wastewaters), and marine (marine clay) origin. The PC2 loadings are highly positive for HCO \(_3^- \) , F?, pH and NO \(_3^- \) , attributing to the alkalinity and pollution controlled processes of geogenic and anthropogenic origins. The PC scores reflect the change of groundwater quality of geogenic origin from upstream to downstream area with an increase in concentration of chemical variables, which is due to anthropogenic and marine origins with varying topography, soil type, depth of water levels, and water usage. Thus, the groundwater quality shows a variation of chemical facies from Na+ > Ca2+ > Mg2+ > K+: HCO \(_3^- \) > Cl? > SO \(_4^{2-}>\) NO \(_3^- \) > F?at high topography to Na+ > Mg2+ > Ca2+ > K+: Cl? > HCO \(_3^- \) > SO \(_4^{2-}>\) NO \(_3^- \) > F? at low topography. With PCA, an effective tool for the spatial controlling processes of groundwater contamination, a subset of explored wells is indexed for continuous monitoring to optimize the expensive effort.  相似文献   

6.
Analysis of hydrogeochemical materials on As distribution in CO2-bearing (carbonate) waters in various regions and the thermodynamic simulation of geochemical processes in rock-CO2-bearing water systems made it possible to constrain the optimal conditions for As transfer from rocks into carbonate waters and the accumulation of this element in the waters. The problem was solved with regard for the various rates of As transitions from rocks to water: (a) high rates of As transitions from rocks in compliance with the ion exchange mechanism and (b) low rates of As transitions from rocks in compliance with the mechanism involving the decomposition of As-bearing minerals. Various mechanisms of As extraction from rocks result in the compositional diversity of the aqueous phase and various As migration species in CO2-bearing waters, which, in turn, control the equilibrium concentration levels of this element. The principally important boundary conditions of As enrichment in CO2-bearing waters are high \(P_{CO_2 } \) and R/W ratios in the geochemical systems, a preliminary increase in the Cl concentration in the CO2-bearing waters, and the origin of these waters at high-density heat fluxes. As migration species were simulated for the model solutions and real carbonate waters of various geochemical types, and it is demonstrated that the predominant As species are oxygen-bearing HAsO 2 0 , and AsO 2 ? at a subordinate role of the sulfide HAs2S 4 2? , and As2S 4 2? — species even at high Σ S2? in the system. Two models of the genesis of solid As sulfides in CO2-bearing waters are analyzed: (1) with oxygen-bearing species (HAsO 2 0 , and AsO 2 ? ), which occur most widely, and (2) with sulfide species (As2S 4 2? , HAs2S 4 ? , and As4S 7 2? ), which occur not as widely.  相似文献   

7.
One hundred forty-eight groundwater samples were collected from the lower part of Wadi Siham catchment area for hydrogeochemical investigations to understand the hydrogeochemical processes affecting groundwater chemistry and their relation with groundwater quality. Groundwater in the study area is abstracted from different aquifers. The study area is characterized by arid climate and extremely high relative humidity. The results indicate that groundwater in the study area is fresh to brackish in nature. The abundance of the major ions is as follows: Na+1?>?Ca+2?>?Mg+2?≥?K+1 and Cl?1?>?HCO 3 ?1 ?>?SO 4 ?2 ?>?NO 3 ?1 . Various graphical and ionic ration plots, statistical analyses, and saturation indices calculations have been carried out using chemical data to deduce a hydrochemical evaluation of the study area. The prevailing hydrogeochemical processes operating in the study area are dissolution, mixing, evaporation, ion exchange, and weathering of silicate minerals in the eastern part (recharge areas). The reverse ion exchange and seawater intrusion control the groundwater chemistry along the Red Sea coast areas and few parts of the study area. Deterioration in groundwater quality from anthropogenic activities has resulted from saltwater intrusion along the coastal areas due to groundwater overpumping and extensive use of fertilizers and infiltration of sewage water. Salinity and nitrate contamination are the two major problems in the area, which is alarming considering the use of this water for drinking.  相似文献   

8.
The chemical composition of aerosols in the Marine Atmospheric Boundary Layer (MABL) of Bay of Bengal (BoB) and Arabian Sea (AS) has been studied during the spring and inter-monsoon (March-May 2006) based on the analysis of water soluble constituents (Na+, NH 4 + , K+, Mg2+, Ca2+, Cl?, NO 3 ? and SO 4 2? ), crustal elements (Al, Fe, and Ca) and carbonaceous species (EC, OC). The total suspended particulates (TSP) ranged from 5.2 to 46.6 μg m?3 and 8.2 to 46.9 μg m?3 during the sampling transects in the BoB and AS respectively. The water-soluble species, on average, accounted for 44% and 33% of TSP over BoB and AS respectively, with dominant contribution of SO 4 2? over both the oceanic regions. However, distinct differences with respect to elevated abundances of NH 4 + in the MABL of BoB and that of Na+ and Ca2+ in AS are clearly evident. The non-sea-salt component of SO 4 2? ranging from 82 to 98% over BoB and 35 to 98% over AS; together with nss-Ca2+/nss-SO 4 2? equivalent ratios 0.12 to 0.5 and 0.2 to 1.16, respectively, provide evidence for the predominance of anthropogenic constituents and chemical transformation processes occurring within MABL. The concentrations of OC and EC average around 1.9 and 0.4 μg m?3 in BoB and exhibit a decreasing trend from north to south; however, abundance of these carbonaceous species are not significantly pronounced over AS. The abundance of Al, used as a proxy for mineral aerosols, varied from 0.2 to 1.9 μg m?3 over BoB and AS, with a distinctly different spatial pattern — decreasing north to south in BoB in contrast to an increasing pattern in the Arabian Sea.  相似文献   

9.
We have analyzed the orbital light curve of the X-ray nova XTE J1118+480 in a “disk + hot line” model based on three-dimensional gas-dynamical computations of gas flows in interacting binary systems. As a result, we have been able to derive reliable parameters for the system: i = 80 ?4 +4 degrees, MBH = 7.1 ?0.1 +0.5 M⊙, M opt = 0.39 ?0.07 +0.15 M⊙.  相似文献   

10.
For the first time, chemical characterization of PM10 aerosols was attempted over the Bay of Bengal (BoB) and Arabian Sea (AS) during the ICARB campaign. Dominance of SO 4 2? , NH 4 + and NO 3 ? was noticed over both the regions which indicated the presence of ammonium sulphate and ammonium nitrate as major water soluble particles playing a very important role in the radiation budget. It was observed that all the chemical constituents had higher concentrations over Bay of Bengal as compared to Arabian Sea. Higher concentrations were observed near the Indian coast showing influence of landmass indicating that gaseous pollutants like SO2, NH3 and NO x are transported over to the sea regions which consequently contribute to higher SO 4 2? , NH 4 + and NO 3 ? aerosols respectively. The most polluted region over BoB was 13°?19°N and 70°?90°E while it was near 11°N and 75°E over AS. Although the concentrations were higher over Bay of Bengal for all the chemical constituents of PM10 aerosols, per cent non-sea salt (nss) fraction (with respect to Na) was higher over Arabian Sea. Very low Ca2+ concentration was observed at Arabian Sea which led to higher atmospheric acidity as compared to BoB. Nss SO 4 2? alone contributed 48% of total water soluble fraction over BoB as well as AS. Ratios SO 4 2? /NO ? 3 over both the regions (7.8 and 9 over BoB and AS respectively) were very high as compared to reported values at land sites like Allahabad (0.63) and Kanpur (0.66) which may be due to very low NO.3 over sea regions as compared to land sites. Air trajectory analysis showed four classes: (i) airmass passing through Indian land, (ii) from oceanic region, (iii) northern Arabian Sea and Middle East and (iv) African continent. The highest nss SO 4 2? was observed during airmasses coming from the Indian land side while lowest concentrations were observed when the air was coming from oceanic regions. Moderate concentrations of nss SO2. 4 were observed when air was seen moving from the Middle East and African continent. The pH of rainwater was observed to be in the range of 5.9–6.5 which is lower than the values reported over land sites. Similar feature was reported over the Indian Ocean during INDOEX indicating that marine atmosphere had more free acidity than land atmosphere.  相似文献   

11.
The specific heat capacity (C p) of six variably hydrated (~3.5 wt% H2O) iron-bearing Etna trachybasaltic glasses and liquids has been measured using differential scanning calorimetry from room temperature across the glass transition region. These data are compared to heat capacity measurements on thirteen melt compositions in the iron-free anorthite (An)–diopside (Di) system over a similar range of H2O contents. These data extend considerably the published C p measurements for hydrous melts and glasses. The results for the Etna trachybasalts show nonlinear variations in, both, the heat capacity of the glass at the onset of the glass transition (i.e., C p g ) and the fully relaxed liquid (i.e., C p l ) with increasing H2O content. Similarly, the “configurational heat capacity” (i.e., C p c  = C p l  ? C p g ) varies nonlinearly with H2O content. The An–Di hydrous compositions investigated show similar trends, with C p values varying as a function of melt composition and H2O content. The results show that values in hydrous C p g , C p l and C p c in the depolymerized glasses and liquids are substantially different from those observed for more polymerized hydrous albitic, leucogranitic, trachytic and phonolitic multicomponent compositions previously investigated. Polymerized melts have lower C p l and C p c and higher C p g with respect to more depolymerized compositions. The covariation between C p values and the degree of polymerization in glasses and melts is well described in terms of SMhydrous and NBO/T hydrous. Values of C p c increase sharply with increasing depolymerization up to SMhydrous ~ 30–35 mol% (NBO/T hydrous ~ 0.5) and then stabilize to an almost constant value. The partial molar heat capacity of H2O for both glasses (\( C_{{{\text{p}}\;{\text{H}}_{2} {\text{O}}}}^{\text{g}} \)) and liquids (\( C_{{{\text{p}}\;{\text{H}}_{2} {\text{O}}}}^{\text{l}} \)) appears to be independent of composition and, assuming ideal mixing, we obtain a value for \( C_{{{\text{p}}\;{\text{H}}_{2} {\text{O}}}}^{\text{l}} \) of 79 J mol?1 K?1. However, we note that a range of values for \( C_{{{\text{p}}\;{\text{H}}_{2} {\text{O}}}}^{\text{l}} \) (i.e., ~78–87 J mol?1 K?1) proposed by previous workers will reproduce the extended data to within experimental uncertainty. Our analysis suggests that more data are required in order to ascribe a compositional dependence (i.e., nonideal mixing) to \( C_{{{\text{p}}\;{\text{H}}_{2} {\text{O}}}}^{\text{l}} \).  相似文献   

12.
Hydrogeochemical investigations were carried out around Fetzara Lake, Northeast Algeria, to assess the quality of groundwater for its suitability for drinking and irrigation purposes. The groundwater chemistry is mainly controlled by the water?Crock interactions, but also influenced by other processes such as evapotranspiration and ion exchange. Groundwater samples collected, during two periods (1993 and 2007) from wells in the area were analyzed for pH, EC, TDS, Ca2+, Mg2+, Na+, K+, CO 3 2? , HCO 3 ? , Cl?, SO 4 2? , and NO 3 ? . The chemical relationships in Piper??s diagram and Gibbs??s diagram suggest that groundwaters mainly belong to noncarbonate alkali type and Cl? group and are controlled by evaporation dominance, respectively, due to the sluggish drainage conditions, greater water?Crock interaction, and anthropogenic activities. A comparison of the groundwater quality in relation to drinking water quality standards proves that most of the water samples are not suitable for drinking. US Salinity Laboratory??s and Wilcox??s diagrams and %Na+ used for evaluating the water quality for irrigation suggest that the majority of the groundwater samples are not good for irrigation.  相似文献   

13.
The crystal structures of synthetic K-dravite [XKYMg 3 Z Al 6 T Si6O18(BO3) 3 V (OH) 3 W (OH)], dravite [XNaYMg 3 Z Al 6 T Si6O18(BO3) 3 V (OH) 3 W (OH)], oxy-uvite [XCaYMg 3 Z Al 6 T Si6O18(BO3) 3 V (OH) 3 W O], and magnesio-foitite [X?Y(Mg2Al)ZAl 6 T Si6O18(BO3) 3 V (OH) 3 W (OH)] are investigated by polarized Raman spectroscopy, single-crystal structure refinement (SREF), and powder X-ray diffraction. The use of compositionally simple tourmalines characterized by electron microprobe analysis facilitates the determination of site occupancy in the SREF and band assignment in the Raman spectra. The synthesized K-dravite, oxy-uvite, and magnesio-foitite have significant Mg–Al disorder between their octahedral sites indicated by their respective average 〈Y–O〉 and 〈Z–O〉 bond lengths. The Y- and Z-site compositions of oxy-uvite (YMg1.52Al1.48(10) and ZAl4.90Mg1.10(15)) and magnesio-foitite (YAl1.62Mg1.38(18) and ZAl4.92Mg1.08(24)) are refined from the electron densities at each site. The Mg–Al ratio of the Y and Z sites is also determined from the relative integrated peak intensities of the Raman bands in the O–H stretching vibrational range (3250–3850 cm?1), producing values in good agreement with the SREF data. The unit cell volume of tourmaline increases from magnesio-foitite (1558.4(3) Å3) to dravite (1569.5(4)–1571.7(3) Å3) to oxy-uvite (1572.4(2) Å3) to K-dravite (1588.1(2) Å3), mainly due to lengthening of the crystallographic c-axis. The increase in the size of the X-site coordination polyhedron from dravite (Na) to K-dravite (K) is accommodated locally in the crystal structure, resulting in the shortening of the neighboring O1–H1 bond. In oxy-uvite, Ca2+ is locally associated with a deprotonated W (O1) site, whereas vacant X sites are neighbored by protonated W (O1) sites. Increasing the size of the X-site-occupying ion does not detectably affect bonding between the other sites; however, the higher charge of Ca and the deprotonated W (O1) site in oxy-uvite are correlated to changes in the lattice vibration Raman spectrum (100–1200 cm?1), particularly for bands assigned to the T 6O18 ring. The Raman spectrum of magnesio-foitite shows significant deviations from those of K-dravite, dravite, and oxy-uvite in both the lattice and O–H stretching vibrational ranges (100–1200 and 3250–3850 cm?1, respectively). The vacant X site is correlated with long- and short-range changes in the crystal structure, i.e., deformation of the T 6O18 ring and lengthening of the O1–H1 and O3–H3 bonds. However, X-site vacancies in K-dravite, dravite, and oxy-uvite result only in the lengthening of the neighboring O1–H1 bond and do not result in identifiable changes in the lattice-bonding environment.  相似文献   

14.
An investigation on quality of groundwater has been carried out in the river basin of Varaha located in Visakhapatnam District, Andhra Pradesh to find out the factors that are responsible for spatial variations of water vulnerability. The study area is underlain by the Precambrian rocks of Eastern Ghats over which the Recent Formations occur. Groundwater is a prime source for drinking and irrigation. The quality of groundwater is fresh and brackish with dominance of the latter. Groundwater samples are categorized into two major clusters A and B, using the dendrogram of cluster analyses. Out of these two major clusters, five sub-clusters I to V in the pre-monsoon season and six sub-clusters I to VI in the post-monsoon season are identified. The sub-clusters I to IV of pre-monsoon and I to V of post-monsoon seasons of the cluster A are characterized by less mineralized groundwater compared to those of V of pre-monsoon and VI of post-monsoon seasons of the cluster B, which represent highly mineralized groundwater. The low to high mineral content follows gradually from upstream to the downstream area, being higher in post-monsoon season in both the clusters A and B, depending upon the source, mineral dissolution, and precipitation, solubility and leaching of ions, ion exchange and adsorption processes. Spatial distributions of the sub-clusters give clues to understand the factors that cause variations of groundwater vulnerability at a specific site, vis-a-vis local and regional lithological and non-lithological influences. As a result, the quality of groundwater on a regional scale changes from Na+ > Mg2+ >Ca2+ > K+: HCO 3 ? > Cl? > SO 4 2? > NO 3 ? > F? in the cluster A to Na+ > Mg2+ >Ca2+ > K+: Cl? > HCO 3 ? > SO 4 2? > NO 3 ? > F? in the cluster B, following the topography. The classification of the area into the zones of relative groundwater vulnerability with respect to drinking water quality of the chemical composition of the sub-clusters helps the planners to identify the specific locations, where the inferior quality of groundwater can occur, for taking the remedial measures.  相似文献   

15.
Groundwater sampling was carried out in fast growing Vijayawada urban agglomeration in Andhra Pradesh state with a view to generate base line data and to assess groundwater quality, its variations vis-à-vis urbanization and hydrochemical characteristics. The groundwaters are found to be fresh to brackish, hard to very hard, often enriched with nitrate, phosphate,and faecal colliform indicating anthropogenic influence on groundwater on account of urbanization. Manganese and iron of geogenic origin are also found to be in high concentrations in some localities. The quality deterioration is more in shallow aquifers, as also in core urban and red soil covered areas. Spatial variations in groundwater quality are discernible, with high concentrations of SO4-4–,NO3- in core urban area suggesting the impact of urbanization. A wide range of chemical constituents indicate water rock interactions as influenced by anthropogenic activities controlling the urban aquifers. The order of abundance of cations is Na>Mg>Ca>K, while the order of abundance of anions is Cl>HCO3>SO4>NO3. The baseline study suggests the need to protect the groundwater resource through sound environmental protection measures for the welfare of the inhabitants in the city around which the new capital is proposed to be constructed for newly formed Andhra Pradesh state in India.  相似文献   

16.
Submarine groundwater discharge (SGD) was quantified at select sites in San Francisco Bay (SFB) from radium (223Ra and 224Ra) and radon (222Rn) activities measured in groundwater and surface water using simple mass balance box models. Based on these models, discharge rates in South and Central Bays were 0.3?C7.4?m3?day?1?m?1. Although SGD fluxes at the two regions (Central and South Bays) of SFB were of the same order of magnitude, the dissolved inorganic nitrogen (DIN) species associated with SGD were different. In the South Bay, ammonium (NH 4 + ) concentrations in groundwater were three-fold higher than in open bay waters, and NH 4 + was the primary DIN form discharged by SGD. At the Central Bay site, the primary DIN form in groundwater and associated discharge was nitrate (NO 3 ? ). The stable isotope signatures (??15NNO3 and ??18ONO3) of NO 3 ? in the South Bay groundwater and surface waters were both consistent with NO 3 ? derived from NH 4 + that was isotopically enriched in 15N by NH 4 + volatilization. Based on the calculated SGD fluxes and groundwater nutrient concentrations, nutrient fluxes associated with SGD can account for up to 16?% of DIN and 22?% of DIP in South and Central Bays. The form of DIN contributed to surface waters from SGD may impact the ratio of NO 3 ? to NH 4 + available to phytoplankton with implications to bay productivity, phytoplankton species distribution, and nutrient uptake rates. This assessment of nutrient delivery via groundwater discharge in SFB may provide vital information for future bay ecological wellbeing and sensitivity to future environmental stressors.  相似文献   

17.
The radio brightness distribution at 5.2 cm has been obtained along the entire solar limb down to a level of 0.01 of brightness temperature at the disk center T 0 c during the solar minimum. The measurements are based on strip scans from the Siberian Solar Radio Telescope. Data reduction included model fitting of an actual solar scan for each position angle. The maximum limb brightness, 1.37 T 0 c , in the derived distribution is at equatorial direction, where the radio radius exceeds the photosphere radius by 7%. Toward the poles, the brightness peak and radio radius gradually decrease to 1.01 T 0 c and 1.005 R0. The derived two-dimensional brightness distribution was used to calculate radio radius as a function of position angle for several wavelengths from 4 to 31.6 cm. These dependences are consistent with RATAN-600 observations at position angles 0° and 25°.  相似文献   

18.
The incorporation of hydrogen into ferrosilite, Fe-bearing enstatite and orthopyroxene containing different trivalent cations (Cr3+ and Al3+, Cr3+ and Fe3+) was investigated experimentally at 25 kbar. Hydrogen concentration was determined by FTIR-spectroscopy on oriented crystal sections and by secondary ion mass spectroscopy, whereas Mößbauer spectroscopy and optical spectroscopy were used to characterise the valence state of Fe in orthopyroxene. Results suggest that hydrogen incorporation in ferrosilite is achieved by a similar mechanism as in pure enstatite. In Cr-bearing samples, however, hydrogen incorporation is reduced by the presence of other trivalent cations by an increased tendency to form Tschermaks substitutions, e.g. Si T 4+ + Mg M1 2+ ? Al T 3+ + Cr M1 3+ . Thus, hydrogen solubility in natural orthopyroxenes from the Earth’s mantle, containing significant amounts of Cr3+, Al3+, and Fe3+, may be much more limited than expected from their trivalent cation content, as a large fraction of the trivalent cations does not participate in H-incorporating reactions as 2 Mg M1 2+ ? M M1 3+ + VM1 + H i + .  相似文献   

19.
Based on the synthesis of hydrogeochemical materials on Sb occurrence in carbonate and thermal waters and thermodynamic simulations, genetic analysis was conducted of the transformations of probable Sb migration species (particularly oxygen-bearing and sulfide ones), and their transformations were calculated depending on the main parameters of hydrogeochemical systems (\(P_{CO_2 } \), T, R/W, Eh, and pH). The oxygen 2HSbO 2 0 + 3H2S = Sb2S3 + 4H2O (2SbO 2 ? + 3HS? + 5H+ = Sb2S3 + 4H2O) and sulfide HSb2S 4 ? + H+ = Sb2S3 cr + H2S (Sb2S 4 2? + 2H+ = Sb2S3cr + H2S) models for the genesis of hydrogenic Sb2S3(cr) were simulated. Information on occurrences of carbonate and thermal waters in various regions worldwide was generalized, and the reasons were identified for the geochemical separation of As and Sb in carbonate and thermal waters. The causes and conditions of an increase in Sb concentrations in thermal waters were revealed, and Sb migration species in carbonate and thermal waters were identified for various parameters of hydrogeochemical systems. Variations in Sb speciation were demonstrated for hydrogeochemical systems depending on their boundary conditions (\(P_{CO_2 } \), T, and R/W). Models were outlined responsible for the precipitation of Sb2S3(cr) from carbonate and thermal waters.  相似文献   

20.
Groundwater, surface water, soil and river sediment samples, and information on land use in the Nanfei River basin (NRB) of China have been analyzed to study the geochemistry, distribution, and mobilization of phosphorus. The distribution of phosphate (PO 4 3??/sup> ) and the relationships between PO 4 3??/sup> and several constituents in groundwater were studied. Partial correlation analysis relating PO 4 3??/sup> to types of land use was conducted using the data analyzing tool SPSS 15.0. The processes controlling the transport of PO 4 3??/sup> are discussed. The conclusions from this study are: (1) urban land use has obvious impact on PO 4 3??/sup> in groundwater, the average concentration of PO 4 3??/sup> being 4.37?mg/L, greater than that resulting from farmland and mixed land use, which have average PO 4 3??/sup> concentrations of 0.10 and 0.18?mg/L, respectively; (2) the partial correlation between PO 4 3??/sup> and types of land use is significant with a coefficient of 0.760; (3) the PO 4 3??/sup> concentrations in surface water are generally higher than those in groundwater, and the total phosphorus (TP) concentrations in river sediments are generally higher than those in soil samples; (4) groundwater is a carrier of PO 4 3??/sup> and is likely responsible for the redistribution of PO 4 3??/sup> in different regions of NRB.  相似文献   

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