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Mercury concentration in sediment cores from Sunderban mangrove wetland, India

The work presents an extended database (n=123) of total mercury (THg) in fine grained sediment fraction (<63 µm) of core samples in ten sampling stations of Sundarban mangrove wetland, India, formed at the estuarine realm of the Hugli (Ganga) River. Results revealed a wide range of spatial, seasonal and intertidal flat variations of THg (7.3 to 93.3 ng/g) with a definite enhancement level at the lower stretch of the estuary which have extreme mangrove vegetation. An overall enrichment of THg in surface/subsurface layers of the core is tentatively explained by remobilization and resuspension of the metal from deeper sediments (36-40 cm). A strong positive correlation was observed between the Hg and clay fraction content of the sediments, while correlations of Hg with organic carbon was poor. Based on the index of geoaccumulation (Igeo), enrichment factor (EF) and anthropogenic factor (AF) values it is considered that the sediments of Sundarban were found to be less polluted with respect to total mercury. The data reported are useful baseline for THg in Sundarban and would be of importance in future sediment quality studies.

mercury; sediment; geoaccumulation index; Sundarban mangrove wetland (India)

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