Heavy metals assessment in Urban air of national capital region of Delhi using spider webs as bioindicator

Abstract

Background and Objective: Delhi represents one of the most polluted cities of the world where the levels of air pollution are alarming. The present study aimed to investigate the efficiency of spider webs as bioindicator of heavy metal pollution in urban air of National Capital Region (NCR) of Delhi. Materials and Methods: The webs of Cyrtophora citricola (C. citricola) (Forskål, 1775) were used that were collected from road side areas at five different sites of NCR region. One laboratory spider web was spun to use as a control sample. The webs were digested with concentrated HNO3. Metal concentrations were analyzed by flame Atomic Absorption Spectrophotometer (AAS) to determine the accumulation (µg g-1) of selected heavy metals (Pb, Zn, Ni, Cd, Cu and Cr) in the webs. Results: The highest concentration of all heavy metals except Cr was recorded in the webs collected from two industrial sites. Also, the mean concentration of all heavy metals except Cr was found to be higher at industrial sites in comparison to residential sites. In the overall area, mean concentration of Zn was found to be highest followed by Pb, Cr, Ni, Cu and Cd. Conclusion: Findings of this study confirm that webs of C. citricola can be used as a bioindicator of heavy metal pollution in air of NCR Delhi and demands for testing the webs of other common spiders of this region for this purpose.