Spatial distribution, contamination levels, and risk assessment of heavy metals along the Eastern India coastline

Abstract

The proposed comprehensive study was accomplished to analyze the ecological phenomenon, heavy metals occurrence, and its significance. The spatial distribution of heavy metals in the sediments such as Cadmium (Cd), Cobalt (Co), Cupper (Cu), Lead (Pb), Mercury (Hg), Nickel (Ni), Zinc (Zn), Iron (Fe), and Chromium (Cr) of the Eastern coastline of India (ECI) was evaluated across 61 sites along the 1400 km stretch of the Bay of Bengal and the Arabian Sea coastline. The heavy metal concentration was higher for Hg (0.08 μg/g) and Cd (3.44 μg/g), likely due to mining and extraction activities. Strong positive correlations ($R^2>0.5,p<0.01$) observed between Cd∼Fe $\left(R^2=0.70\right)$, Cd∼-Cr $\left(R^2=0.68\right)$, Co∼Zn $\left(R^2=0.79\right)$, Cu∼Ni $\left(R^2=0.73\right)$ suggesting co-miming sources while negative correlations Ni∼Cr $\left(R^2=-0.50\right)$, Ni∼Pb $\left(R^2=-0.56\right)$, Cu∼Pb $\left(R^2=-0.58\right)$ indicate the separation of these metals in sediments due to geochemical conditions and tailing disposal. The heavy metals, Co, Cu, Pb, Ni, Fe, and Cr were under the concentrations proposed by sediment quality guidelines (SQGs). It indicated there is fewer immediate effects of heavy metals, however, even at low levels metals like Hg, Cd, and Pb can cause chronic exposure effects, bioaccumulation and subclinical health impacts over time. The stations of Utkal (UC 14–UC 18) and Coromandel (CC 8–CC 11) coastline act as shipping ports and are involved in mining activities and recorded geological weathering of rocks in these areas, compared to other sampling locations along Utkal, Andhra and Coromandel coastline.