Mercury content and the ratio of stable nitrogen isotopes in the hair of residents from industrial city and specially protected natural area of Russia.

The mercury content in the hair of residents in the industrial city of Cherepovets (0.297 mg/kg) is three times lower than that of residents in the specially protected natural area of Kirillovsky district (0.877 mg/kg), which is approximately 110 km away from Cherepovets. In both the residents of the industrial city and in the protected area, the mercury content in hair increases with the age of the individuals. In the population of the city, there is no difference between the mercury content in the hair and the frequency of fish consumption. The mercury content in the hair of the population from the protected area depends on the frequency of fish consumed in their diet. The average value of the ratio of stable nitrogen isotopes (δN) in the hair of the participants is 10.11‰. No differences have been established between the ratio of stable nitrogen isotopes (δN) in the hair of residents of the industrial city (10.00‰) and the protected area (10.19‰). People with a mercury content in their hair above the median value had statistically significantly higher δN values in both residents of industrial city and protected area. A correlation was established between the isotopic signature of nitrogen and the amount of mercury in the hair both in the whole sample (Rs = 0.515, at p = 0.000), and in the industrial city (Rs = 0.425, at p = 0.002) and in the protected area residents (Rs = 0.706, at p = 0.000). That may be due to the differences in diet, as rural population has a traditionally high level of consumption of wild freshwater fish from local reservoirs while people from industrial city mainly purchase fish (seafood, marine fish, freshwater fish) from supermarkets.