A Sustainable Approach for Monitoring of Ambient Air Quality Considering Lichen as a Bioindicator: A Case Study for Two Major Traffic Intersections of Kolkata

The enhanced air pollution levels in Kolkata are primarily attributed to escalated vehicular population. In this study, lichen has been utilized as a biomonitoring agent to detect overall air pollution level. Lichen species that are found in a given area exhibit measurable responses to environmental changes. Lichen biodiversity counts can be used as accurate indicators of the state of the environment. Lichen species are generated through mutualistic symbiosis of an algae or cyanobacteria (phycobiont) and a fungus (mycobiont). In this segment, lichen species have been characterized based on their growth forms, predominantly crustose and foliose variety of lichen was observed. From monitoring lichen species found in the study area, near major traffic intersections, it was observed that initial growth was steady although it was accompanied by a period in which a linear growth of thallus was observed. The Index of Atmospheric Purity (IAP) is calculated for detecting growth activity and abundance of lichen species. Further, the permissible range of IAP in terms of pollution levels has been analysed. Thus, based on the results it is observed that in the study area the overall pollution level in terms of tree specimens studied for IAP calculation is moderate.