Magnetic susceptibility mapping of roadside pollution on BHU campus was done by researchers
Varanasi: A study on roadside pollution on the Banaras Hindu University (BHU) campus conducted by a group of researchers suggested that deciduous trees plantation and improvement in the drainage system within the campus are essential to reduce the accumulation of pollutants in the topsoil near the sites of infrastructural development and busy roads. This results in a smaller stay time of the heavy metals in the topsoil, roadside dust and tree leaves.
For this study, the magnetic susceptibility mapping of roadside pollution on BHU campus was done by the researchers Sayandeep Banerjee, Ankit Kumar, Virendra Rana, Sayan Maity and Hari B Srivastava of BHU’s Centre of Advanced Study in Geology. The study was published in the Current Science in October this year. The researchers claimed that this study presents the first quantitative assessment of roadside pollution on the BHU main campus, since its establishment in 1916.
According to the study, to identify the heavy minerals/metals in the soil, dust and leaf samples, scanning electron microscopy (SEM) was used on selected soil and leaf samples in the Subcontinental Lithospheric Mantle Laboratory, Centre of Advanced Study in Geology, BHU. For mapping of roadside pollution, 106 locations were selected consisting of 75 along the crescent-shaped roads designated as the main traffic roads in the campus, and 31 along the radial roads connecting the semicircular roads using a GPS device for accuracy. A total of 212 samples of the topsoil were collected during pre-monsoon (106) and post-monsoon (106) seasons to estimate the variation in roadside pollution round the year. A few leaf samples from the trees along the roads at the same locations were also taken.
The soil, dust and leaf samples were analysed under SEM using back-scattered electrons (BSEs) over carbon-coated sample surface. Subsequently, energy-dispersive X-ray spectroscopic (EDS) analysis was performed on selected phases for a semi-quantitative chemical analysis to confirm the heavy mineral phases present in the soil and leaf samples. Significant increase in zones of high magnetic susceptibility was observed near the area around BHU main gate, Sir Sundarlal Hospital, Shri Vishwanath Temple, areas around Kendriya Vidyalaya BHU near the Nariya gate, approach road to Sear gate, adjacent region to the Hyderabad gate and the road connecting the Shri Vishwanath Temple and IIT BHU entrance.
“The SEM and EDS analyses confirm the occurrence of heavy minerals like magnetite, haematite, ilmenite, zircon, pyrite in the topsoil of the BHU campus,” said Banerjee. He said the results of the study could be applied for environmental monitoring and prioritization of land use and other anthropogenic activities on the campus. The spatial distribution of the zones of high and low roadside pollution is controlled by the emission of selected heavy metals due to fuel combustion and/or construction works related to infrastructural development inside the BHU campus.
According to a recent database, about 30,000 students are enrolled in BHU across seven institutes and 16 faculties (streams) and about 140 departments. Apart from the 76 hostels occupied by students, a few thousand faculty members and staff members across disciplines reside with their families in several residential colonies and flats, and guest houses on the campus, making it a township with a population of more than 50,000 people. A wide variety of flora and fauna also contribute to the campus ecosystem. Thus, regular environmental monitoring and assessment is necessary for the BHU campus.
The researchers said the determination of heavy metals and magnetic pollutants is crucial because potentially harmful heavy metals can be absorbed in the human body through inhalation ingestion, and dermal contact because of the small size of the heavy metal particles.
It should be noted that the micrometre-sized magnetic iron oxides may induce oxidative stress pathways, which leads to the formation of free radicals, and might cause DNA damage.
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