Abstract
Heavy metals are mostly discharged from several anthropogenic sources in the lower Gangetic delta. They are a matter of great concern due to their non-conservative nature. Heavy metals Zn, Cu, and Pb, were analyzed in the estuarine water and thallus body tissue of Enteromorpha compressa from 10 different stations in the lower Gangetic delta complex through three seasons. The levels of heavy metals varied as per the order Zn > Cu > Pb in both the aquatic phase and biological sample, irrespective of stations. The maximum concentration of Zn was observed in Kakdwip (Stn. IV) and both Cu and Pb in Nayachar Island (Stn. III). The minimum was observed in Bagmara (Stn. X) for all metals in the seaweed sample through all the seasons. The levels of all dissolved heavy metals were maximum in Nayachar Island (Stn. III) and lowest in Bagmara (Stn. IV). A distinct seasonal pattern is observed for all the selected metals with the highest value during monsoon, followed by postmonsoon and premonsoon. The Bioaccumulation Factors (BAF) computed for all the selected heavy metals exhibit the highest value for Pb, followed by Zn and Cu. The highest BAF observed for Pb is an issue of grave concern due to its toxic nature compared to Zn and Cu. ANOVA computed on the data sets of dissolved and bioaccumulated heavy metals and BAFs exhibit significant Spatio-temporal variation, suggesting the need for seasonal and station-wise monitoring, preferably in context to the BAF. The spatial variation in the level of heavy metals in the seaweed species Enteromorpha compressa is due to differences in activities and sources of pollution in these regions. The overall result suggests that seaweed may be a potential bio-purifier in the coastal area mainly exposed to many anthropogenic activities.