Environmental geochemistry of heavy metals in coral reefs and sediments of Chabahar Bay

Abstract

The amount of heavy metals in coral reefs and sediments and their impact on the marine environment is of great importance. The present study aimed to determine the quantity and quality, distribution, and origin of the elements introduced into the reefs and sediments of Chabahar Bay. In this research, specimens of coral reefs and sediments were collected from six stations in coral regions of Chabahar Bay. Then, standard grain size analysis was performed on the sediment sample. An ICP-MS analysis was done to identify heavy metals. The results indicate that the sediment type of coral regions of Chabahar Bay is gravelly sand, gravelly muddy sand, and muddy gravelly sand. Moreover, sediments have two clastic and biochemical origins, and their formation environment is a carbonate environment consisting of small and single reefs, often coral reefs. On the other hand, the concentrations of cadmium and lead in sediments as well as the concentrations of cadmium and cobalt in the coral reefs of Chabahar Bay are higher than concentrations of them in the earth's crust and global marine sediments. The highest contamination is associated with cadmium and lead, followed by aluminum and nickel (moderate contamination rate) and then, other elements (low contamination rate). Because of a significant/high correlation, the nickel and vanadium elements are the sources of oil pollution. Considering the maximum distribution of heavy metals, the breakwater and basin of Shahid Beheshti Port and the Great Sea are considered as the extremely contaminated places in the coral regions of Chabahar Bay, confirming the organic and human-induced origins of contaminations.