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1.
In the present paper, an environmental analysis of Manikpur area, Korba coalfield, Bilaspur, M.P., India is undertaken. The
area lies in the Geological Survey of India Toposheet no. 64J/11 Latitude 82°42′54″–82°45′10″ North; Longitude 22°18′46″–22°19′46″
East. The paper deals with pollution and its control measures through the natural plants found in the vicinity of the coalmines,
namely Mangifera indica, Eucalyptus spp., Cassia siamea, Delbergia sissoo, etc. The plants control the Suspended Particulate Matter (SPM), Nitrous Oxides (NOx), Sulphur Oxides (SOx) of the mines
and mining site. Therefore, plantation in the mining site should be encouraged.
Received: 12 May 1998 · Accepted: 6 October 1998 相似文献
2.
On the influence of spatial heterogeneity on an internal boundary layer at a short fetch 总被引:1,自引:0,他引:1
B. S. Murthy R. Latha Cini Sukumaran A. Shivaji S. Sivaramakrishnan 《Journal of Earth System Science》2009,118(1):61-70
Surface layer meteorological data collected at a coastal site, at Vasco-Da-Gama (15°21′N, 73°51′E, 58.5m MSL) (13–18 July,
2002) with prevailing southwesterly surface winds are analyzed to study the characteristics of internal boundary layer at
a short fetch using an instrumented tower (9 m). The spectral and turbulence characteristics of wind are compared with earlier
measurements made at a comparatively homogeneous terrain and the standards available in literature. The study show the smaller
eddies in the vertical velocity spectrum attains equilibrium with the underlying surface at a short fetch itself and follows
spectral similarity. However, this is not followed by longitudinal and transverse velocity spectra under unstable as well
as stable conditions. 相似文献
3.
Impact of Berm Breaching on Hyperbenthic Macroinvertebrate Communities in Intermittently Closed Estuaries 总被引:1,自引:0,他引:1
Adrian W. T. Lill Gerard P. Closs Marc Schallenberg Candida Savage 《Estuaries and Coasts》2012,35(1):155-168
Berm breaching of intermittently closed estuaries, either naturally or due to management practices, results in a physicochemical
disturbance due to the flushing of water, material and biota into the ocean and the subsequent tidal influx. In 2007 and 2008
comparative and controlled studies were employed in three New Zealand estuaries: Sawmill Creek (46°04′ S 170°12′ E), Otokia
Creek (45°57′ S 179°20′ E) and Kaikorai Lagoon (45°56′ S 170°23′ E), to investigate the impact of berm breaching on the hyperbenthic
macroinvertebrate community in intermittently closed estuaries. Significant changes in community structure occurred in both
the weekly comparative and the controlled studies (ANOSIM P < 0.01). Furthermore, the catch per unit effort of both total
and key invertebrate taxa significantly increased after breaching (ANOVA P < 0.01). However, substantial numbers of individuals were expelled into the ocean (5,800 individuals, 20-min sample) while
new taxa immigrated into the estuaries. Along with migration-related changes to community structure, berm breaches also resulted
in the loss of ∼80% of inundated habitat and the concentration of existing populations. Consequently, the management of intermittent
estuary connections to the ocean has implications for the ecology of individual, managed estuaries and also for regional coastal
populations of epibenthic invertebrates. 相似文献
4.
Impact of geohydrology and neotectonic activity on radon concentration in groundwater of intermontane Doon Valley, Outer Himalaya, India 总被引:1,自引:0,他引:1
Radon concentration was measured in 133 water samples from tubewells, handpumps, dug wells and springs of the Doon Valley,
Outer Himalaya, India. The observed radon values were found to vary from 10 to 154 Bq/l whereas radium in selected water samples
varied from 0.11 to 0.75 Bq/l. Three different clusters of high radon values were observed in the north-western, central and
south-eastern parts of the Doon Valley. These clusters were found to be associated with tectonics (thrust/fault) and associated
uranium mineralization in the area. In general, radon concentration in groundwater was found to be positively correlated with
the depth of the wells, whereas no significant correlation was observed between radon concentration in groundwater and the
water temperature, pH value, conductivity and altitude of the water samples. An attempt has also been made to determine the
nature and extent of aquifers in the Doon Valley on radon concentration in groundwater. The variation in radon concentration
within the groundwater of the study area was found to be controlled by the neotectonic activity and geohydrological processes
that occur in the area. The impact of these activities on radon concentration in groundwater are discussed.
Received: 17 September 1999 · Accepted: 11 April 2000 相似文献
5.
The major chemical components of bauxite deposits of Belgaum (76° 24′E : 15° 54′N) and Yercaud (78° 14′E : 11° 48′N) areas
have been determined. A chemical continuity between parent rocks (zone I) to bauxites (zone IV) via clay (zone II) and laterites
(zone III) clearly indicates that bauxites have been derived byin situ weathering of the respective parent rocks. 相似文献
6.
Continuous measurements of aerosol size distributions in the mid-point diameter range 20.5–500 nm were made from October 2005
to March 2006 at Pune (18°32′N, 73°51′E), India using Scanning Mobility Particle Sizer (SMPS). Volatilities of atmospheric
aerosols were also measured at 40°, 125°, 175°, 300° and 350°C temperatures with Thermodenuder–SMPS coupled system to determine
aerosol volatile fractions. Aerosols in nucleated, CCN and accumulated modes are characterized from the measured percentage
of particles volatized at 40°, 125°, 175°, 300° and 350°C temperatures. Averaged monthly aerosol concentration is at its maximum
in November and gradually decreases to its minimum at the end of March. The diurnal variations of aerosol concentrations gradually
decrease in the night and in early morning hours (0400–0800 hr). However, concentration attains minimum in its variations
in the noon (1400–1600 hr) due to higher ventilation factor (product of mixing height and wind speed). The half an hour averaged
diurnal variation of aerosol number concentration shows about 5 to 10-fold increase despite the ventilation factor at higher
side before 1200 hr. This sudden increase in aerosol concentrations is linked with prevailing conditions for nucleation bursts.
The measurement of volatile fraction of ambient aerosols reveals that there are large number of highly volatile particles
in the Aitken mode in the morning hours and these volatile fractions of aerosols at temperatures <150°C are of ammonium chloride
and ammonium sulfate, acetic and formic acids. 相似文献
7.
Luis Cumbal Paulina Vallejo Brigida Rodriguez Dina Lopez 《Environmental Earth Sciences》2010,61(2):299-310
The arsenic content of geothermal hot springs and their sediments in the north-central Andean region of Ecuador has been investigated.
The area of study is located between parallels 1°11′N and 1°30′S and includes five provinces. The area is rich in geothermal
surface manifestations that are mainly used for medicinal baths in recreational complexes. Unfortunately, water residuals
without treatment are released from the recreational facilities to surrounding water bodies. The results indicate that total
arsenic in geothermal waters in this region has a range of 2–969 μg As/L, and sediments contain arsenic ranging from 1.6 to
717.6 mg/kg. Chemical analyses of sediment samples show the presence of sulfur, iron, aluminum and calcium. A high concentration
of natural organic matter was also found in some samples (20–29.5%); thus sorption and coprecipitation can be the main mechanisms
of As immobilization on mineral phases and natural organic matter. 相似文献
8.
The thermal stabilities and decay kinetics of three peroxy radicals (Centers #1, B and B′) and three other radiation-induced
defects (#3, C′ and E1′) in natural quartz from the high-grade McArthur River uranium deposit (Athabasca basin, Canada) have been investigated by
isochronal and isothermal annealing experiments and electron paramagnetic resonance (EPR) spectroscopy. Single-crystal EPR
spectra of isochronally (2 h) annealed quartz show that these centers all grow in intensity to 280°C and then decay with further
increase in temperature, but their disappearance temperatures differ markedly and depend on the initial concentrations (e.g.,
Center #1 in a dark smoky quartz is annealed out at 380°C, B and B′ at 420°C and #3 and C′ at 580°C). The isothermal decay
processes of these centers are all of the second order type. The calculated activation energies for the peroxy radicals [#1
and B + B′ at 0.36 (9) and 0.83 (8) eV, respectively] are smaller than those of Centers #3, C′ and E1′ [1.09 (8), 1.24 (8) and 1.45 (7) eV, respectively]. Gamma-ray irradiations of thermally bleached quartz restore a fraction
of the peroxy radicals, suggesting that their diamagnetic precursors are stable up to at least 800°C. The unusual decay characteristics
of “peroxy radicals” in quartz reported in the literature are shown to most likely arise from multiple radiation-induced defects.
These results have implications for not only applications of peroxy radicals in quartz for EPR dating but also better understanding
of thermoluminescence and cathodoluminescence spectra of this mineral. 相似文献
9.
Muhammad Rafique Saeed Ur Rahman Muhammad Akram Matiullah 《Environmental Earth Sciences》2012,66(4):1225-1232
This paper presents the results of indoor radon concentration measurements in 120 dwellings of district Sudhnuti of Azad Kashmir. Measurements were taken with CR-39 passive alpha track detector. CR-39 based box type radon detectors were installed in a bedroom and living rooms of each house. The detectors were retrieved after exposing to indoor radon for period of 6 months and then etched in 6 M NaOH at 80°C for 16 h, the observed track densities were converted in to the indoor radon concentration. Indoor radon concentration varied from 20 ± 12 to 170 ± 4 Bq m−3 for the houses of the district Sudhnuti. Arithmetic mean (AM), geometric mean (GM) and geometric standard deviations (GSD) were found to be 82 ± 6, 77 ± 6 and 1.51, respectively. The minimum value of weighted average radon concentration was recorded in one of the house of Mang town, whereas the maximum value was found in the Pattan Sher Khan region. Doses due to indoor radon exposure vary from 0.50 ± 0.31 to 4.28 ± 0.11 mSv year−1 AM, GM and GSD. of mean effective doses were found to be 2.06 ± 0.13, 1.95 ± 0.18 and 1.51, respectively. According to the recommendations made by the Health Protection Agency, UK (200 Bq m−3) all the houses surveyed are within the safe limits. 相似文献
10.
Simulation of chloride migration rates in Paleo Pennar Delta Region, Coastal Andhra Pradesh, India 总被引:1,自引:0,他引:1
Quaternary alluvial aquifers in the paleo Pennar delta region of Andhra Pradesh (Long. 80°0′ and 80°12′; Lat. 14°40′ and
14°20′) constitute an important coastal strip, with potential fresh groundwater resources and several well fields in operation.
The lineament patterns and traces of paleo channels provide basic information on the configuration and boundaries of paleo
delta and the possible neotectonic movements in the region. The paleo delta region is essentially characterized by freshwater
aquifer systems at the near-surface depths, (up to 50 m from ground level) with transmissivity values in the system ranging
from 1200 to 2500 m2/day. This groundwater system has been subjected to heavy draft situation over the last two decades, parlicularly near the
outer rim of the delta where an unlined brackish-water canal runs parallel to the coast imparting chloride contamination to
the adjoining fresh aquifers. A two-dimensional solute transport model solution was applied to assess chloride migration rates
inland under different hydraulic stresses, combining finite difference solution of flow equation and the method of characteristic
solution of solute transport equation. Groundwater flow and chloride migration patterns/rates were obtained for different
simulated stress events in the delta system, and measures required to protect the freshwater resources ara outlined.
Received: 2 January 1997 · Accepted: 4 November 1997 相似文献
11.
Summary Augite and diopside crystals from the Oligo-Miocene high-Mg and high-Al basalts, basaltic andesites and andesites of Montresta
(Sardinia, Italy) have been analysed by means of X-ray single crystal diffraction and electron microprobe. It has been found
that crystallization or equilibration processes took place within the crust at pressures below 5 kbar. In particular, samples
from high-Al basalts, basaltic andesites and andesites crystallised at pressures below one kbar while those from high-Mg basalts
crystallised in a range from about 1.5 to 4.5 kbar. The intracrystalline temperatures range between about 550 °C for high-Mg
basalts and 750 °C for andesites. The M2′ site is occupied in each of the studied crystals, which implies slow cooling rates. 相似文献
12.
Radon measurements in soil and groundwater (springs, thermal springs and handpumps) were made in a variety of lithological
units including major thrusts between Mandi and Manali in Himachal Himalaya. Analysis of radon data in light of lithological
controls and influence of deep-seated thrusts has been made to elucidate the causative factors for anomalous emanation of
radon. The lithological types include banded gneisses, schists, quartzite, granite, phyllites, volcanics and mylonites. The
low-grade metasedimentries of Shali and Dharamsala generally show low and narrow range of radon concentration in water (5.6–13.4 Bq/l)
as well as in soil (1.8–3.2 kBq/m3) except for the samples related to thrusts. On the other hand, sheared and deformed rocks of Chail and Jutogh show moderate
radon content (average 5.03 kBq/m3, range 2.9–11.1 kBq/m3) in soil. However, the groundwater radon concentration shows wide variation in different types of sources (2.1–80.8 Bq/l).
The quartzite and volcanic rocks of Rampur formation in this area present as a window separated by Chail thrust. Radon emanations
on these rock types are relatively high (6.3–68.1 Bq/l in water and 5.5–15.9 kBq/m3 in soil) and are exceptionally high in samples that are related to uranium mineralization, deep-seated thrusts and hot springs
(13.5–653.5 Bq/l). It is generally observed that anomalous high radon content is associated with mineralization, deeper source
and tectonic discontinuities. Whereas it is obvious that subsurface radioactive mineralization would facilitate enhanced radon
production, however, thrust plains provide easy pathways for escape of gases from the deeper sources. Shallow and deep sources
of the groundwater have contrasting radon content particularly in the deformed and metamorphosed rocks of Jutogh and Chail.
Shallow groundwater sources, mainly handpumps, have lower radon concentration due to limited superficial water circulation,
whereas deeper sources, mainly perennial springs, show higher radon content because of larger opportunity for water–rock interaction. 相似文献
13.
Abhishek Saha Avik Dhang Jyotisankar Ray Suvankar Chakraborty David Moecher 《Journal of Earth System Science》2010,119(3):365-381
Field studies supplemented by petrographic analyses clearly reveal complete preservation of ophiolite suite from Port Blair
(11°39′N: 92°45′E) to Chiriyatapu (11°30′24″N: 92°42′30″E) stretch of South Andaman. The ophiolite suite reveals serpentinite
at the base which is overlain unconformably by cumulate ultramafic-mafic members with discernible cumulus texture and igneous
layering. Basaltic dykes are found to cut across the cumulate ultramafic-mafic members. The succession is capped by well exposed
pillow basalts interlayered with arkosic sediments. Olivine from the basal serpentinite unit are highly magnesian (Fo80.1–86.2). All clinopyroxene analyses from cumulate pyroxenite, cumulate gabbro and basaltic dyke are discriminated to be ‘Quad’ and
are uniformly restricted to the diopside field. Composition of plagioclase in different lithomembers is systematically varying
from calcic to sodic endmembers progressively from cumulate pyroxenite to pillow basalt through cumulate gabbro and basaltic
dyke. Plagioclase phenocrysts from basaltic dyke are found to be distinctly zoned (An60.7-An35.3) whereas groundmass plagioclase are relatively sodic (An33-An23.5). Deduced thermobarometric data from different lithomembers clearly correspond to the observed preservation of complete ophiolite
suite. 相似文献
14.
VHF amplitude scintillations recorded during the daytime period from January 1991 to December 1993, April 1998 to December
1999 and January 2008 to December 2008 at low latitude station Varanasi (geographic lat. = 25°15′N; long. = 82°59′E; geomagnetic
lat. = 14°55′N, long. = 154°E, dip angle = 37.3°, sub-ionospheric dip = 34°) have been analyzed to study the behaviour of
ionospheric E-region irregularities during the active solar and magnetic periods. The autocorrelation functions, power spectral
densities, signal de-correlation times are computed to study the temporal features of ionospheric E-region irregularities
linked with daytime scintillations. Derived spectral index ranges between −2 and −9. Assuming velocity of irregularities,
the characteristic lengths of the E-region irregularities are estimated. We have estimated the minimum and maximum range of
scale length of sporadic-E (E
s
) irregularities to be observed over Varanasi. These results are in close agreement with those reported from this latitude
region. 相似文献
15.
Grain boundary diffusion rates of oxygen, potassium and calcium in fine-grained feldspar aggregates were determined experimentally.
The starting materials were a natural albite rock from the Tanco pegmatite and aggregates hot-pressed from fragments of Amelia
albite or Ab, Or and An composition glasses. The technique employed isotopic tracers (18O, 41K, 42Ca) either evaporated onto the surface or in an aqueous solution surrounding the sample, and depth profiling using an ion
microprobe (SIMS). From the depth profiles, the product of the grain boundary diffusion coefficient (D′) and effective boundary
width (δ) was calculated using numerical solutions to the appropriate diffusion equation. The experimental reproducibility
of D′δ is a factor of 3. A separate determination of D′ independent of δ yields an effective grain boundary width of ∼3 nm,
consistent with high resolution TEM observations of a physical grain boundary width <5 nm. Oxygen (as molecular water) grain
boundary diffusion rates were determined in the Ab and Or aggregates at 450°–800° C and 100 MPa (hydrothermal), potassium
rates in Or aggregates at 450°–700° C both at 0.1 MPa (in air) and at 100 MPa (hydrothermal), and calcium rates in An aggregates
at 700°–1100° C and 0.1 MPa (in air). Oxygen grain boundary diffusion rates are similar in all three of the Ab aggregates
and in the Or aggregate. Potassium and oxygen depth profiles measured in the same samples yield different D′δ values, confirming
a diffusional transport mechanism. Potassium diffusion in the Or aggregate has a greater activation energy (216 vs 78 kJ/mol)
than oxygen, and the Arrhenius relations cross at ∼625° C. Potassium D′δ values in Or aggregates are about a factor of five
greater in hydrothermal experiments at 100 MPa than in experiments at 0.1 MPa in air. Calcium grain boundary diffusion rates
in An aggregates are 4 to 5 orders of magnitude slower than potassium in Or and have a greater (291 kJ/mol) activation energy.
This suggests that differences in formal charge and/or size of diffusing species may play an important role in their relative
grain boundary diffusion rates.
Received: 24 December 1993 / Accepted: 16 June 1994 相似文献
16.
Guangjian Wu Baiqing Xu Chenglong Zhang Shaopeng Gao 《Environmental Earth Sciences》2010,61(6):1227-1237
This study measured the major element concentrations and compositions of atmospheric dust aerosol samples collected weekly
for nearly 2 years at Mt. Muztagata, a remote and high-elevation site (38°17′N, 75°01′E, 4,430 m) in the Eastern Pamirs. Inductively
coupled plasma mass spectroscopy (ICP–MS) results show that on the weekly timescale, air at Muztagata contained average element
Al concentrations of 842 ng m−3 between June 2004 and December 2005, and 509 ng m−3 between June 2005 and April 2006. The dust load over the Eastern Pamirs appears to be far lower (by more than an order of
magnitude) than those in northern China. The Muztagata dust aerosols show Ca/Al ratios (~0.7) and Fe/Al ratios (~0.7) that
differ from that in northern China. The general homogeneity exists in the major element compositions, expect Ca/Al ratios
which show minor but clear seasonal variations. Element ratios vary with aerosol concentration. Results indicate that concentrations
and compositions of Asian dust change significantly between different emission regions, and confirm that major element ratios
can be used to efficiently characterize the dust aerosols composition at different sites in northern China. 相似文献
17.
M. Liu J. C. Peterson Richard A. Yund 《Contributions to Mineralogy and Petrology》1997,126(3):217-223
The growth rates of albite and pyroxene (enstatite + diopside + spinel) reaction rims were measured at 1000°C and ˜700 MPa
and found to be parabolic indicating diffusion-controlled growth. The parabolic rate constants for the pyroxene (+ spinel)
rims in samples with 0.5 wt% H2O added or initially vacuum dried at 25°C and 250°C are 1.68 ± 0.09, 0.54 ± 0.05 and 0.25 ± 0.06 μm2/h, respectively. The values for albite rim growth in samples initially dried at 60°C and with 0.1 wt% H2O added are 0.25 ± 0.04 and 0.33 ± 0.03 μm2/h, respectively. The latter values were used to derive the product of the grain boundary diffusion coefficient D′A, where A = SiO2, NaAlO2, or NaAlSi−1, and the grain boundary thickness δ in albite. The calculated D′SIO2δ in the albite aggregate for the situations of two different water contents are about 9.9 × 10−23 and 1.4 × 10−22 m3 s−1, respectively. Both the rate constants and the calculated D′Aδ demonstrate that the effect of water content on the grain boundary diffusion rate in monomineralic albite and polymineralic
pyroxene (+ spinel) aggregates is small, consistent with recent studies of monomineralic enstatite and forsterite rims.
Received: 1 July 1995 / Accepted: 1 August 1996 相似文献
18.
Volume and grain boundary diffusion of calcium in natural and hot-pressed calcite aggregates 总被引:3,自引:0,他引:3
Calcium self-diffusion rates in natural calcite single crystals were experimentally determined at 700 to 900° C and 0.1 MPa
in a stream of CO2. Diffusion coefficients (D) were determined from 42Ca concentration profiles measured with an ion microprobe. The Arrhenius parameters yield an activation energy (Q)=382±37 kJ/mol
and pre-exponential factor (D0)=0.13 m2/s, and there is no measurable anisotropy. Calcium grain boundary diffusion rates were experimentally determined in natural
(Solnhofen) limestone and hot-pressed calcite aggregates at 650° to 850° C and 0.1 to 100 MPa pressure. The Solnhofen limestone
was first pre-annealed for 24 h at 700° C and 100 MPa confining pressure under anhydrous conditions to produce an equilibrium
microstructure for the diffusion experiments. Values for the product of the grain boundary diffusion coefficient (D′) and
the effective grain boundary diffusion width (δ) were determined from 42Ca concentration profiles measured with an ion microprobe. The results show that there is no measurable difference between
D′δ values obtained for pre-annealed Solnhofen samples at 0.1 and 100 MPa or between hot-pressed calcite aggregates and pre-annealed
Solnhofen samples. The temperature dependence for calcium grain boundary diffusion in Solnhofen samples annealed at 0.1 MPa
is described by the Arrhenius parameters D′
0δ=1.5×10−9 m3/s and Q=267±47 kJ/mol. Comparison of the results of this study with previously published data show that calcium is the slowest
volume diffusing species in calcite. The calcium diffusivities measured in this study place constraints on several geological
processes that involve diffusive mass transfer including diffusion-accommodated mechanisms in the deformation of calcite rocks.
Received: 19 December 1994/Accepted: 30 June 1995 相似文献
19.
20.
Geochemistry of groundwater,Markandeya River Basin,Belgaum district,Karnataka State,India 总被引:1,自引:0,他引:1
The Markandeya River Basin stretches geographically from 15o56′ to 16o08′ N latitude and 74o37′ to 74o58′ E longitude, positioned in the midst of Belgaum district, in the northern part of Karnataka. The groundwater quality of 54 pre-monsoon samples in the Markandeya River Basin was evaluated for its suitability for drinking and irrigation purposes by estimating pH, EC, TDS, hardness and alkalinity besides major cations (Na+, K+, Ca2+, Mg2+) and anions (HCO3–, Cl–, SO42–, PO43-, F-, NO3–), boron, SAR, % Na, RSC, RSBC, chlorinity index, SSP, non-carbonate hardness, Potential Salinity, Permeability Index, Kelley’s ratio, Magnesium hazard and Index of Base Exchange. Negative Index of Base Exchange indicates the chloro-alkaline disequilibrium in the study area and the majority of water samples fall in the rock dominance field based on Gibbs’ ratio. Permeability indices of classes I and II suggest suitability of groundwater for irrigation. Based on Cl, SO4, HCO3 concentrations, water samples can be classified as normal chloride (96.3%) and normal sulfate (94.4%) and normal bicarbonate (44.4%) water types. 相似文献