Ahmedabad: Trees are our shield against pollutants

AHMEDABAD: What can cities do to guard themselves from harmful gases and smoke billowing out of factory exhausts. Today, each of the four major Gujarat cities — Ahmedabad, Surat, Vadodara and Rajkot — are surrounded by harmful chemical industrial clusters and burning waste mounds that smoke our air with carcinogens.
A team of researchers from environmental science department of the Institute of Science and Technology for Advanced Studies and Research (ISTAR), Vallabh Vidyanagar and local bodies found that trees such as banyan, peepal, ashok and champak proved to be effective in controlling pollution. But in the process, these benign species take the maximum blow after absorbing the pollutants. The study found that when these trees were planted in areas with higher level of pollutants, they had lower chlorophyll content as certain pollutants diminish the total chlorophyll content.



The ISTAR researchers had measured factors such as high values of Air Pollution Tolerance Index (APTI) and the Anticipated Performance Index (API) of different tree species that were key determinants of minimising the threat of pollutants from industrial areas. The study was mostly carried out in a 3km radius from Nandesari industrial area which had good greenery and lesser nearby air pollutants. For collection of gaseous and particulate pollution, High Volume Air Sampler was used for 24 hours with flow rate of one litre per minute.

ISTAR researchers Dhruti Patel and Nirmal Kumar calculated scientific parameters such as total chlorophyll, ascorbic acid, leaf pH, relative water content and used them for defining sensitivity or resistance of plants towards different air pollutant concentration. “Plant sensitivity and tolerance to air pollutants varied with above parameters. Chlorophyll content decreased due to production of reactive oxygen species (ROS) in the chloroplast underwater stress condition,” claimed the research. The study also observed that changes in chlorophyll content caused change in the rate of photo-synthesis as well.

In the plant, higher ascorbic acid concentration of leaves lead to an effective strategy to protect thylakoid membranes from oxidative damage under water stress conditions. “Alkaline particles such as limestone and dust particle in air usually damaged plant surfaces while high pH improved tolerance against air pollution,” observed the research.