Geospatial risk assessment and trace element concentration in reef associated sediments, northern part of Gulf of Mannar biosphere reserve, Southeast Coast of India

Highlights: • The present work was carried out to study the potential ecological risk and sediment pollution level of coral reef ecosystem • The distribution of OM and CaCO₃ were locally controlled by the mangrove litters and fragmented coral debris. • The elements were supplied through urbanization and coal incinerating power plants from the northern part of Gulf of Mannar. • The accumulation level of trace elements clearly suggests that the coral reef ecosystem is under low to moderate risk. - Abstract: Fifty two surface sediments were collected from the northern part of the Gulf of Mannar biosphere reserve to assess the geospatial risk of sediments. We found that distribution of organic matter and CaCO₃ distributions were locally controlled by the mangrove litters and fragmented coral debris. In addition, Fe and Mn concentrations in the marine sediments were probably supplied through the riverine input and natural processes. The Geo-accumulation of elements fall under the uncontaminated category except Pb. Lead show a wide range of contamination from uncontaminated-moderately contaminated to extremely contaminated category. The sediment toxicity level of the elements revealed that the majority of the sediments fall under moderately to highly polluted sediments (23.07–28.84%). The grades of potential ecological risk suggest that predominant sediments fall under low to moderate risk category (55.7–32.7%). The accumulation level of trace elements clearly suggests that the coral reef ecosystem is under low to moderate risk.