Pyrophyllite deposit at Madrangjodi is a large lensoidal massif overlain unconformably by Dhanjori quartzite and underlain
by the parent Singhbhum granite (Phase — II). Pyrophyllite and quartz are the major minerals with minor to trace amounts of
muscovite, chloritoid opaques and tourmaline. It is broadly divisible into lamellar, granular and schistose varieties. SiO2 (66.90–74.36%) and Al2O3 (20.80–27.54%) are the major oxides. The major elements data indicate its derivation from Singhbhum granite with depletion
of SiO2 and increment of Al2O3. Trace and REE data are discussed to corroborate its genesis. 相似文献
The picturesque Nainital Lake, in the Uttarakhand state of India, is one of the major tourist attractions in the northern
part of India. The increasing tourism and population around these lakes are a major concern for the ecology and good sustenance
of the lakes. The present study is aimed to understand the behaviour of nutrients and metals in the sediment and their association
with chemical forms in the lake. The study was accomplished by studying the water, interstitial water and sediments for major
oxides, nutrients and metals in the lake. The different chemical forms of phosphorus and metals in the sediments were done
using sequential extraction procedures. The water chemistry (Ca + Mg:Na + K) and the sediment chemistry (CIA and Al2O3/K2O) show that the rocks in the catchment area play an important role in the geochemistry of the lake. The metals in the water
also show that the Tallital basin is more polluted than the Mallital basin, may be due to the influence of Bus station. The
high concentration of chloride, NH4, SO4 and metals in the sediment water interface and the interstitial water shows denitrification, sulfidisation and sulfide oxidation
in the anoxic bottom water. The sediment composition shows that the phosphorus in the water is sequestered as carbonate flour
apatite, and the metals precipitate as carbonate. The geo- accumulation index shows that the metals zinc, cobalt and nickel
show moderate polluted nature than other metals. In general, the lake is less affected by anthropogenic activities. The chemical
processes undergoing within the lake, like sulfidisation and sulfide oxidation, oxide dissolution and denitrification and
organic matter degradation play an important role in the remobilization of the metals from the lake sediments. 相似文献
Spent mushroom compost (SMC) is widely used as reactor matrix in passive bioreactor involving sulfate reducing bacteria (SRB)
for acid mine drainage (AMD) treatment. Follow-up our previous report, recent work has been established the extent of activity,
sustained organic carbon availability, and the biochemical events of successive alkalinity producing system-based chemo-bioreactor
for continuous performance using SMC. Removal of iron and sulfate from influent was over 77 and 90%, respectively, for first
13 weeks, while sulfate removal efficiency suddenly dropped down to 31% thereafter. Ahead of 13th week, process failure was
beginning to be noticed when available dissolved organic carbon (DOC) value dropped down to 50 mg/L. SRB population was mostly
affected with DOC drought at this stage. Sulfur was one of the major elements found with other tested metals in blackish green
effluent precipitate. Sulfide compounds of the tested metals were formed on both exhausted chemo-bioreactor bed and precipitate.
FTIR analysis indicated that SMC was responsible for metal binding and available nutrients supply. The present study revealed
the feasibility of SMC as a host for treating AMD by this chemo-bioreactor that will assist in designing the continuous treatment
practice. 相似文献
Phosphorus (P) plays an important role in the eutrophication of river and marine environments. The adsorption-desorption processes of P by estuarine sediment were studied to better understand the P behaviour in the Loughor Estuary in Carmarthen Bay, UK. Three types of models were used to estimate the P adsorption isotherm for five sediment samples from the Loughor Estuary. The Langmuir adsorption isotherm showed a good fit with the linear (data) isotherm. The P desorption from bed sediment was measured as the easy exchangeable P (MgCl2 extractable). A negative correlation was found between adsorbed P in bed sediment and median particle size. A positive correlation was also found between P adsorbed and metals such as iron (Fe), aluminium (Al) and calcium (Ca) as well as the total organic carbon (TOC).
Distribution of biochemical properties, morphological and functional characteristics of bacteria in the extreme sedimentary environment of the Central Indian Basin (CIB) was examined in relation to geotechnical properties and sediment texture. Interrelationships between these parameters in siliceous northern sediments were compared to southern pelagic clay to understand relationships and to appreciate mining implications. Clay impacted lipids negatively and silt positively in the south. Geotechnical properties had the opposite influence on the distribution of coccoidal and rod forms of bacteria. Rods were affected negatively by water content/porosity and positively by wet bulk density in the north suggesting their preference for deeper niches. Shear strength affected coccoidal distribution negatively in the south. Competition for labile substrates by coccoidal forms in the surface layers could also have restricted the rods to the deeper regions. Principal component analysis (PCA) further strengthened our inference that the distribution of rod forms increased with depth. Enzymatic properties of bacterial isolates also showed that the rods were able to degrade substrates like gelatin and DNA. These observations suggest that they are capable of degrading relatively more recalcitrant compounds in the deeper layers. The minor components, like the rod morphotypes and sand content, could wield a large influence on the variability of other parameters. 相似文献
The succession of lithofacies of a part of the Barren Measures Formation of the Talchir Gondwana basin has been studied by
statistical techniques. The lithologies have been grouped under five facies states viz coarse-, medium-, and fine-grained
sandstones, shale and coal for statistical analyses. Markov chain analysis indicates the arrangement of Barren Measures lithofacies
in the form of fining upward cycles. A complete cycle consists of conglomerate or coarse-grained sandstone at the base sequentially
succeeded by medium-and fine-grained sandstones, shales and coal at the top. The entropy analysis puts the Barren Measures
cycles into A-4 type cyclicity, which consists of different proportions of lower, upper and side truncated cycles of lithologic
states. Regression analysis indicates a sympathetic relationship between total thickness of strata (net subsidence) and number
of cycles and an antipathic relationship between average thickness and number of sedimentary cycles. The cyclic sedimentation
of the Barren Measures Formation was controlled by autocyclic process which occurred due to the lateral migration of streams
triggered by intrabasinal differential subsidence. In many instances, the clastic sediments from the laterally migrating rivers
interrupted the cyclic sedimentation resulting in thinner cycles in areas where the number of cycles are more. Principal component
and multivariate regression analyses suggest that the net subsidence of the basin is mostly controlled by the thickness of
sandstones, shale beds and coal stringers. 相似文献
Deformation in active mountain belts like the Himalaya is manifested over several spatial and temporal scales and collation
of information across these scales is crucial to an integrated understanding of the overall deformation process in mountain
belts. Computation and integration of geological shortening rates from retrodeformable balanced cross-sections and present-day
convergent rates from deforming mountain belts is one way of integrating information across time-scales. The results from
GPS measurements carried out in NE India indicate that about 15–20 mm/yr of convergence is being accommodated there. Balanced-cross
sections from the NE Himalaya indicate about 350–500 km of shortening south of the South Tibet Detachment (STD). Geothermobarometry
suggest that the rocks south of the STD deformed under peak metamorphic conditions at ∼ 22 Ma. This indicates a geological
convergence rate of ∼ 16–22 mm/yr which appears to be fairly consistent with the GPS derived convergence rates. Approximately
1.5 to 3.5 mm/yr (∼ 10–20 %) of the total N-S of the present-day convergence in the NE Himalaya is accommodated in the Shillong
Plateau. In addition, ∼ 8–9 mm/yr of E-W convergence is observed in the eastern and central parts of the Shillong Plateau
relative to the Indo-Burman fold-thrust belt. Balanced cross-sections in the Indo-Burman wedge together with higher resolution
GPS measurements are required in the future to build on the first-order results presented here. 相似文献
Investigation of biogeochemistry and amino acids on a 30-m-long core from Mansar Lake has thrown light on palaeoclimate variability
during the Holocene period. The C/N ratio between 6 and 10 with some deviations and δ13C mostly between −20 and −22‰ in the
shallow core, as well as a C/N ratio greater than 13 reaching from 19 to 20 and correspondingly lower δ13C of –28‰ in the
deeper core suggest an aquatic source of carbon in the former and a cellulose-rich land plant source in the latter. This is
supported by the abrupt increase in organic carbon content in the deeper core compared to the shallow core, which indicates
a hot and wet climatic regime during the early Holocene and dry and cold during the late Holocene period. The amino acid data
AA-C/C% and AA-N/N% are higher in shallow sediments compared to deeper sediments, indicating an aquatic plant source in the
shallow core and greater supply of land plant sources in the deeper core. The lower percentage of the non-protein amino acids
β-alanine (ALA) and γ-amino-butyric acid in the shallow core compared to the deeper core indicates different sources of organic
matter in the lake basin. The higher amino acid ratio Asp/β-Ala (16.99 av.) and Glu/γ-Aba (18.18 av.) in the shallow core
and lower ratios (10.32 and 12.41 av.) in the deeper core, and Asp/Glu (1.52 av.) and β-Ala/γ-Aba (1.61 av.) ratios in the
former, which are potential indicators of the nature of the organic matter, are higher in the shallow core relative to the
deeper core (1.33 and 1.23 av.), indicating relative biodegradation of organic matter in deeper sediments. It has been observed
that the organic matter associated with the dry season is relatively less biodegraded, as evidenced from their higher ratios,
and is more biodegraded in the wet season as their ratios are lower in the river sediments. In the absence of a bacterial
contribution of organic matter from the soil source in this lake, since Mansar Lake is a non-drainage type, it is envisaged
that the climatic variation may be responsible for biodegradation in the deeper core sediments. Therefore, the C/N ratio and
δ13C values supported by amino acid data, the latter being significant in revealing primary productivity and a terrestrial
source of organic matter, suggest a hot and wet climatic regime during the early Holocene (ca. 7580 bp) and a dry and cold in the late Holocene period (ca. 4050 bp). 相似文献