Mercury concentration in water and fish samples along south coast of the Caspian Sea

Mercury (Hg) contamination in marine ecosystems is a major threat to human health in the developing countries like Iran. The main route of mercury exposure is from consumption of fish and seafood. Upon entering mercury in human bodies, Hg is converted into methyl mercury, which may lead to serious implications including neurological disorders, reproductive abnormalities, kidney failure, emotional instability, gingivitis and tremors. Therefore, research on mercury concentrations in marine ecosystems (water and fishes) can be help to protect human health and reduce the risks of mercury contamination.
In this study in order to evaluate the concentrations of Hg in water and fish, water samples (36 stations), fish tissue livers (n=33) and muscles (n=33) of four fish species from the Caspian Sea (southern coasts) were collected and analyzed. For determination of Hg in water and fish samples, Voltammetry and GF-AAS techniques were used, respectively.
The results showed that the average Hg concentration detected in water samples was 1.657 (μg/L) and in fish muscle and liver tissues were 68.636 and 125.606 (μg/g.dw), respectively. The bioaccumulation factor showed that mercury concentrations from water to fish are in the range of 14 to 80 times. The highest levels of mercury in water and fish were observed in the southwest coasts of the Caspian Sea.
According to USEPA and SPPA (China) standards, more than 58 % of the water samples collected from the southern coasts of the Sea was polluted by mercury. However, the average concentrations of mercury in fish samples were less than the standards by WHO and EPA.