Assessment of trace metal contamination, total organic carbon and nutrient accumulation in surface sediments of Monastir Bay (Eastern Tunisia, Mediterranean Sea)

Abstract

Monastir Bay, located on the eastern coast of Tunisia was, a few decades ago, characterized by high marine biodiversity. However, the environmental quality of this coast is affected by several urban and industrial discharges. An evaluation of heavy metal contamination, total organic carbon and nutrient accumulation was undertaken to assess the quality of surface sediments. The geochemical data and statistical approaches show that the coast extending from Khniss to Sayada is a region contaminated with trace metals (Zn, Cu and Ni), with higher contents of TOC, TN, TP and TS and lower values of Eh, suggesting a confined zone with anoxic environmental conditions. The C/N, the S/C and the C/P ratios shows that the sediments of the nearshore zone of Monastir Bay are largely higher (C/N) or lower (S/C and C/P) than the expected ratios in marine sediments suggesting anthropogenic inputs of organic matter. The submarine topography associated with weak hydrodynamic currents acts as physical barriers limiting the exchange with open sea.