Historical sedimentary deposition and ecotoxicological impact of aromatic biomarkers in sediment cores from ten coral reefs of the Persian Gulf, Iran.

The present study determines the levels, vertical distributions, source apportionment and ecological risk of polycyclic aromatic hydrocarbons (PAHs) in ten sediment cores of coral reef in the Persian Gulf, Iran, one of the important oil polluted marine areas in the world. The main purpose of this study was to determine the spatio-vertical distribution pattern of PAHs pollution at the four hot spot zones on the Gulf: dense industrial, medium industrial, urbanized and non-impacted zones over the past few years. Sediment quality and ecological risk were also assessed in order to determine the pollutants of concern. In detail, 23 parent (PPAHs) and 16 alkylated PAHs (APAHs), along with retene and perylene, were determined in sediment cores (0-40 cm depth). The vertical distribution of all PAHs showed a wide variation among sampling stations and depths, with a decreasing trend of concentration from surface to bottom, and a peak at 12 cm. Total concentrations of PPAHs and APAHs ranged from 35 to 1927 ng g dw and 19 to 1794 ng g dw respectively, with the highest concentrations at the industrial zone. The diagnostic ratio for PAHs and perylene (3 to 1277 ng g dw) indicated mixed sources of PAHs, with dominance of petrogenic origins at the industrial zone and natural diagenetic inputs, respectively. The PAH concentration depicted a significant decreasing trend along the length of the core with an abrupt increase within the core length 12-20 cm. Temporal variations in contaminants can be linked to economic, coastal developments and industrial growth. Overall, the baseline data on geographical distribution, congener profiles, sources and vertical deposition of PAHs in the Persian Gulf area would be useful to establish proper monitoring plans for this sensitive ecosystem.