Investigating the Trend of Increasing Oil Pollution in Surface Sediments along the Coastal Area of Mazandaran Province

Coastal areas of Caspian Sea have been affected by pollution in recent years. These areas are exposed to environmental problems due to the presence of hydrocarbon resources in the Caspian Sea basin as well as human factors. Investigating the concentration of normal alkanes in the studied stations shows that the amount of hydrocarbons contaminated in the studied area, compared with previous year’s studies, shows a significant increase in concentration. The concentration of n-alkanes are among the 24.3 µg/g (the minimum concentration) in Nashtarood Station to 690.7 µg/g (the maximum concentration) in Noshahr Station and most of the stations have moderate concentration of n-alkanes. The increase of pollution in recent years as a result of increased oil activities related to the exploration, production and exploitation of oil resources and human factors. Also, the presence of Hyrcanian forests on the southern shores of the Caspian Sea and increasing seizure of forests in recent years have also led to increased contamination in the region due to pollution transmission to the Caspian Sea. In order to determine the origin of normal alkanes in the region, the indexes of CPI, LMW / HMW, Pristane / Phytane, n-C17 / Pristane and n-C18 / Phytane were used. The results show petrogenetic and biogenic inputs at sampling stations that petrogenetic contamination is prevalent in the region.