210Pb dating and neutron activation analysis of the Sundarban mangrove sediments: sedimentation rate and metal contamination history

In this study, alpha spectrometry and neutron activation analysis were applied to assess the mass accumulation rate, contamination history, and ecological risk of the Sundarban mangrove sediments. The mass accumulation rates of sediments using 210Pb dating determined for the first time in this area ranged from 0.068 to 3.20 kg m−2 y−1, with an average of 0.61 kg m−2 y−1. The contamination history of 11 metal(loid)s (Al, Ca, V, Cr, Fe, Ni, Cu, Zn, As, Hg, and Pb) was assessed. Different environmental contamination indices suggested that Sundarban mangrove sediments were contaminated by As. Considering different sediment quality guidelines, it was observed that Cr, Ni, and As posed occasional adverse biological effects on marine organisms. Multivariate statistical approaches were applied to elucidate the origin and transport behavior of the studied metal(loid)s in the mangrove ecosystem which suggested that sources of metal(loid) pollution were both anthropogenic and geogenic. The results from this study should improve the knowledge of metal contamination and ecological risk to biota to develop new strategies and enlarge management practices to save sensitive mangrove ecosystems.