1. ENVIROMENTAL POLLUTION
THE MAGNETIC SUSCEPTIBILITY (MS) MAPPING OF ROAD DUST FROM KOLKATA CITY TO INFER THE DEGREE OF
ENVIROMENTAL POLLUTION
Rimjhim Maity, Punyotoya Paul, Debesh Gain, Supriya Mondal, Shashwat Kumar Singh
Department of Geological Sciences, Jadavpur University, Kolkata , India
*Presenting Author:
Abstract
pollution mapping (2D and 3D on the basis of magnetic susceptibility using MS2B.
to infer the degree of environmental pollution on the basis of frequency dependent susceptibility values for some specific areas.
Pollution of road dusts is significantly reducing environmental quality. The pollutants of most concern are heavy metals and organic contaminants. Road sides in metropolitan cities like Kolkata are commonly polluted by particulate matter derived mostly from emission of traffic: motor vehicles, abrasion of tiers, brake linings, dispersion of construction material, etc. The magnetic proxies can be used as indicator for environmental pollution. The aims of our study are to trace the distribution and concentration of contaminants in road dust along major roads and highways of Kolkata city carrying appreciable traffic by using magnetic parameters. The frequency dependent susceptibility measurements are used to detect the presence of ultrafine (<0.03μm) superparamagnetic ferri-magnetic minerals and are roughly inferred the degree of pollution on the basis of the fact ‘The higher the MS, the lower the FDS (Frequency Dependent Susceptibility), the more seriously the Road dust may be polluted’. Clearly enhanced values of the MS, varies from 100 to 150 x10-8 SI, were found on the roadsides which are about 10 times greater than the areas which are not influenced by traffic emissions (about 20–30 x10-8 SI). The distribution of the susceptibility values of all sites represent polluted areas strongly influenced by traffic frequency, constructional hazards, meteorological conditions and other factors.
Results
Magnetic Susceptibility Data
A single profile was measured in order to qualitatively determine the degree of magnetic pollution along a road with high traffic frequency. The highest susceptibility value is x 10-8 m3/kg for (L-21) and the lowest value is x 10-8 m3 /kg for (L-44).
MAPPING
The whole mapping is carried out between the latitude ⁰N ⁰N and longitude ⁰E ⁰E.In order to highlight the trend of susceptibility vs. Position of road junctions, all 50 profiles measured for the high resolution mapping are plotted in Map:4.1 and Map:4.2. And Map:4.3 shows 3D mapping of original data shows high and low peaks.
GRAPH BETWEEN Xfd AND %Xfd
The graph shows the trend of %Xfd values with respect to Xfd value which is generally showing no specific trend. But, it is clear that the places of high susceptibility values having low %Xfd value than the places of low susceptibility values.
Another part is that the maximum %Xfd value is 3.01 means that the all samples have very low concentration of superparamagnetic minerals(<10%).
Fig. 3: 3D susceptibility
mapping shows
high and low
peak.
Fig.4: Graph shows the
trend of %Xfd
values with
respect to Xfd
values.
Discussion
The highest MS value is measured from L-21 and lowest value from L-44. The data analysis to detect the degree of pollution, we selected some major areas having high and low MS values and carried out susceptibility measurements for dual frequency susceptibility. All data includes that dust of low susceptibility like L-44, have FDS values are >1.5% but high susceptibility area like L-21 have FDS value<1.5%.It can be deduced that if pollutants are present in dust, its MS will increase and FDS will drop. We can also infer that, taking earlier references, maximum studied areas having FDS value<3% means the concentration of super paramagnetic grains are very less(<10%) which indicates that the dust samples having high susceptibility are because of pollutants present in them.
Introduction
Pollution studies aim to identify areas of high pollution levels and method to reduce daily exposure to these harmful particles. However, many techniques currently in use are time-consuming, expensive and therefore spatially limited than magnetic techniques. So, magnetic susceptibility as a proxy for pollutant loading. Kolkata, a city in the eastern part of India, is one of the most polluted metropolises city of India. This study is carried out to assess the roadside dust at 50 major roads and crossings. The magnetic susceptibility is used as a magnetic proxy for the susceptibility mapping to infer the environment pollution..
Conclusions
Methods and Material
Fig. 1: Histogram showing Mass Susceptibility values of all locations.
Areas which are not affected by anthropogenic input are characterized by low and stable susceptibility values. A magnetite-like phase was found to be responsible for the enhancement of the magnetic susceptibility of the road dust. Summarizing the susceptibility results, dust samples in the investigated road sides are clearly influenced by anthropogenic emissions up to a distance of 5 m from the road and down to a depth of half a meter. The most striking result of this investigation is that our data demonstrate the potential of magnetic susceptibility mapping for the study of environmental pollution. Our results show that the pollutants in road dust have different magnetic properties from the sediments and the unpolluted soils. We can conclude that, the study of magnetic susceptibility and frequency-dependent susceptibility can serve as a convenient and effective method for the detection of environmental pollution.
The field work concerns the main roads and crossings of metro city Kolkata. Area covers approximately 185km2 with 5.2 million residents and dust samples are collected during spring season, from areas which have high traffic circulation for magnetic studies. Samples were collected from the road crossings. In the laboratory, samples were dried at room temperature and the samples from each site were put into 6 standard identical plastic cubical boxes which are pre weighted (8 cm3) for magnetic analysis. Then, all the samples were subjected to measure under low frequency using Bartington Susceptibility Meter (MS2B) put into the dual frequency (0.48 and 4.8 kHz) for susceptibility (k) measurements in CGS unit. This study mainly consists of following objectives:
tracing the distributions and concentrations of magnetic contaminations along major roads and highways of Metro city Kolkata.
Fig. 2: Contour map showing detailed susceptibility results for all
sampling sites.
Contact
References
Rimjhim Maity
Department of Geological Sciences, Jadavpur University, Kolkata.
Phone:
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