Organic and Total Mercury Concentration in Fish Muscle and Thermodynamic Study of Organic Mercury Extraction in Fish Protein

MeHg and total mercury concentrations were determined in the muscle tissues of four fish species (Cyprinus carpio, Rutilus frisii, Carassius auratus and Esox lucius) from Anzali wetland (Guilan, Iran). Fish with the highest amount of MeHg was selected to determine the thermodynamic parameters of MeHg extraction. The extractions process was performed in the range of temperatures 331.15 to 367.15 K and at atmospheric pressure. Results show the extraction of MeHg from SH groups of sulfhydryl proteins was an endothermic process with a positive value for entropy and Gibbs free energy changes at the room temperature. Significant difference was found between MeHg content at T=367.15 K and other temperatures. Correlation coefficients results showed that the mercury concentration in muscle tissue was significantly related to the length and weight of fish (p≤0.01). Also, thermodynamic parameters of methylmercury extractions had significant correlation (p≤0.05) with length and weight of the six fish specimen.