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31.
Geochemical fractionation of heavy metals in Chilka Lake (east coast of India)—a tropical coastal lagoon 总被引：1，自引：0，他引：1
Chilka lake, the largest coastal lagoon of Asia is one of the most dynamic ecosystems along the Indian coast. Historically the lagoon has undergone a considerable reduction in surface area due, in part, to input from natural processes but mostly due to human activities. The purpose of this investigation is to document the heavy metals' affinity for specific geochemical phases in the recently deposited sediments in the lagoon. Thirty-three samples were collected and analyzed for different geochemical phases of Fe, Mn, Cu, Cr, Ni, Pb, and Zn utilizing a sequential extraction scheme. In the nonlithogenous fraction, the exchangeable fraction was not geochemically significant, having <2% of the total metal concentration for all the elements. However, the carbonate fraction contained the following percentages of the total concentration: <1% Fe, 13% Mn, 6% Cu, 4% Cr, 8% Ni, 13% Pb, and 12% Zn, suggesting the detrital origin of the sediments. Reducible and organic matter-bound fractions were the significant phases in the nonlithogenous fraction, containing 9% Fe, 16% Mn, 15% Cu, 16% Cr, 16% Ni, 14% Pb, and 14% Zn in the former and 4% Fe, 3% Mn, 17% Cu, 3% Cr, 14% Ni, 15% Pb, and 14% Zn in the latter. The phenomenon has been attributed to the scavenging affinity of Fe-Mn oxides and affinity for sorption into organic matter of the lagoon sediments. The lithogenous, residual fraction generally considered as a guide for natural background values was determined to contain 87% Fe, 67% Mn, 61% Cu, 77% Cr, 61.3% Ni, 56% Pb, and 60% Zn of the total concentrations. 相似文献
32.
S. Panigrahy R. P. Singh S. A. Sharma M. Chakraborty 《Journal of the Indian Society of Remote Sensing》1995,23(4):175-184
Some of the basic requirements for cropping system analysis are updated information on crops grown, their phenological behaviour, method and duration of establishment and harvest, inter and intra crop variability, sequential cropping patterns. The next generation Indian Remote Sensing Satellite with high repeat cycle opens new possibility of crop surveys to derive such information. In this study, an attempt has been made to analyse cropping system at district level using simulated IRS-1C Wide Field Sensor (WiFS) data. Data acquired for nineteen dates during 1992–93 season for Bardhaman district, West Bengal has been used. It was feasible to derive accurate information on cropping pattern, crop rotation, crop duration, progress of harvest, crop growth profiles and annual crop acreage using multidate data. It was observed that even a seven to eight day interval of data acquisition during critical growth periods significantly affected classification and identification accuracy. 相似文献
33.
Rabindra K. Panigrahy S. S. Ray S. Panigrahy 《Journal of the Indian Society of Remote Sensing》2009,37(2):325-333
This present study was conducted to find out the usefulness of SWIR (Short Wave Infra Red) band data in AWiFS (Advanced Wide
Field Sensor) sensor of Resourcesat 1, for the discrimination of different Rabi season crops (rabi rice, groundnut and vegetables)
and other vegetations of the undivided Cuttack district of Orissa state. Four dates multi-spectral AWiFS data during the period
from 10 December 2003 to 2 May 2004 were used. The analysis was carried out using various multivariate statistics and classification
approaches. Principal Component Analysis (PCA) and separability measures were used for selection of best bands for crop discrimination.
The analysis showed that, for discrimination of the crops in the study area, NIR was found to be the best band, followed by
SWIR and Red. The results of the supervised MXL classification showed that inclusion of SWIR band increased the overall accuracy
and kappa coefficient. The ‘Three Band Ratio’ index, which incorporated Red, NIR and SWIR bands, showed improved discrimination
in the multi-date dataset classification, compared to other SWIR based indices. 相似文献
34.
Characterisation of Residue Burning from Agricultural System in India using Space Based Observations
Chandra Prakash Singh Sushma Panigrahy 《Journal of the Indian Society of Remote Sensing》2011,39(3):423-429
Biomass burning is a global phenomenon with agriculture residue burning having a sizeable share. Biomass burning is a major source of emission of green house gases (GHGs). Thus the space-based observations of global distribution of fire form a key component of climate change studies. This study is a step towards understanding the spatio-temporal occurrence of agricultural residues burning in Indo-Gangetic plains of India using fire products from space borne satellites. The 3 years daily active fire data of MODIS (Aqua/Terra) from August, 2006 to July, 2009 have been used in this study. The data analysis showed that out of total fire events, around 69% contribution comes from agricultural areas and remaining (31%) comes from non-agricultural areas. This is mainly due to the intensive cultivation in this belt. The characterisation analysis revealed that, 84% of agriculture residues burning is from Rice-Wheat system (RWS) alone and remaining 16% in other types of crop rotations. The fire incidents were very high in October–December (55%) compared to that in March–May (36%), further indicating that burning of rice residue is more prevalent than that of wheat. 相似文献
35.
36.
Sujay Dutta Suresh K. Singh Sushma Panigrahy 《Journal of the Indian Society of Remote Sensing》2014,42(2):353-361
Remote sensing technology becomes an effective and inexpensive technique for detecting disease in vegetation. In this study, an attempt has been done to discriminate healthy and late blight affected crop using remote sensing based indices such as NDVI and LSWI. NDVI and LSWI spectral profiles between healthy and late blight affected crop shows large difference. Mean difference in reflectance between two acquired dates Jan. 10 and 29, 2009 crop clusters varied from 31.28 % in red band, 7.7 % in NIR band and 6.23 % in SWIR bands in healthy crops while in late blight affected crops it is ?15.5 % in red, 44.4 % in NIR and ?14.61 % in SWIR bands. Negative percentage differences in reflectance indicate reflectance increases from Jan. 10, 2009 to Jan. 29, 2009, while positive difference indicate decrease in reflectance between the two dates. Since potato is an irrigated crop, these differences in reflectance are attributed to prevalent disease at that time. It is found that severely affected areas are Bardhman, Arambag, Bishnupur, Ghatal and Hugli taluka with crop damage areas are 4036.66, 1138.68, 2025.23, 469.15, and 380.08 ha, respectively. 相似文献
37.
River water quality in weathered limestone: A case study in upper Mahanadi basin, India 总被引：1，自引：0，他引：1
Stromatolitic limestone and calcareous shale belonging to Chattisgarh Supergroup of Proterozoic age dominate the upper part
of the Mahanadi river basin. X-ray diffractogram (XRD) of limestone rocks show presence of a significant amount of calcite,
dolomite and ankerite. Shales of various colours contain calcite and dolomite. It is observed that congruent dissolution of
carbonate minerals in the Charmuria pure limestone has given rise to a typical karst topography. On the other hand, limestones
are also seen to support red and black soil profiles. This indicates that the limestone bedrock undergoes a parallel incongruent
weathering, which leaves a residue of decomposed rock. The XRD analyses reveal that the limestone soils thus formed contain
an assemblage of quartz, clays and Fe-oxides. It is likely that the silicate component trapped during deposition of the stromatolitic
limestone weathers incongruently resulting in diverse soil profiles. Carbonate and silicate mineral weathering schemes have
been worked out to explain the soil formation, fixation of Al in clay minerals, and Fe in goethite. The water quality parameters
such as Ca, Mg and HCO3 in the river water suggest under saturation with respect to calcite and dolomite. The mineral stability diagrams indicate
that kaolinite and Ca-smectite are stable in the river water environment, hence they occur in suspended sediments and soils.
The dominant influence of carbonate weathering on the water quality is observed even in the downstream part of the river outside
the limestone terrain. 相似文献
38.
Three-date ERS-1 SAR data acquired on August 24, September 28 and November 2, 1995, was used to classify rice crop in a predominant rice growing region of West Bengal. India, Artificial neural network, maximum likelihood, decision rute and K-Means clustering classifiers were used. Classification accuracy was evaluated from the error matrix of same set of training and validating pixels. Rice classification accuracy improved significantly using neural network classifier. The decision rule based classifier performed equally good for most of the sites, indicating the feasibility of deriving a common rule based algorithm for large area application. Law aecuracy was observed for maximum likelihood classifier. 相似文献
39.
K R Manjunath N Kundu S Panigrahy 《Journal of the Indian Society of Remote Sensing》1998,26(4):197-208
The present study evaluates the performance of Indian Remote Sensing (JRS) LISS Jl and LISS III data having spatial resolutions of 36 m and 23.5 m respectively in the Classification accuracy of rice, mustard and potato crops grown in West Bengal, India. The role of Middle infra-red (MIR.) band, of IRS 1C LISS III was also investigated in this context. The results indicated that in case of crop like rice which was grown over large contiguous fields, no significant change in classification accuracy was observed between LISS II and LISS III data. However, the accuracy increased by 5–7 per cent with the inclusion of MIR band mainly due to better separability between lowland rice and other hill vegetation. In case of crops like mustard and potato which were grown on small size or less contiguous fields, the classification accuracy increased by 5–8 per cent due to higher spatial resolution of LISS III. Inclusion of MIR band did not improve the accuracy of these crops. 相似文献
40.
M. P. Kale G. Talukdar R. K. Panigrahy S. Singh 《Journal of the Indian Society of Remote Sensing》2010,38(3):401-413
Fragmentation leads to the loss of connectivity among forested landscapes, which is important for biological conservation
and biodiversity maintenance. Fragmentation analysis carried out on 20 years time interval in northern-Western Ghats revealed
that, losses under moderate and high fragmented forests have decreased from 1985–87 to 2005; however, it is not enough to
compensate the loss of intact forests (not fragmented). The area of dense forests in intact forests has decreased from 1985–87
to 2005, this essentially means the loss of quality habitat in the area. While investigating connectivity between fragmented
patches by taking different topographical and ecological parameters into the consideration, it was observed that potential
connectivity exists between protected areas present in northern and southern areas. 相似文献