a modified method for the determination of organic mercury in biota [great cormorants (phalacrocorax carbo)] by advanced mercury analyzer

background: contagion of aquatic ecosystems to heavy metals especially mercury (hg) has risen concerns about healthiness of marine organisms. organic mercury compounds are highly toxic for animals, and its detection in various samples is frequently needed. in present study we have described a new method for measurement of organic mercury and total mercury concentration in great cormorants (phalacrocorax carbo) of southern coasts of caspian sea. also, resultant values have been compared with world health standards. methods: 18 great cormorants were hunted randomly in southern coasts of caspian sea during march 2009. analysis of organic and total mercury was performed on samples from their liver, kidney and muscle, with advanced mercury analyzer (model leco, ama 254) for the first time in iran. this method can be used for others biota. results: mean concentrations of total mercury were 5.67, 3.59 and 2.26 mg/kg in animal liver, kidney and muscle respectively from which 82, 79 and 58 percent were comprised from organic mercury respectively. comparison of resultant figures showed statistically significant differences (p<0.05) but no differences were found between different sexes (p=0.69). conclusion: total mercury concentrations in tissues of great cormorant were outstandingly higher than who, fao and epa standards. it is a serious threat for end users of the bird meat especially insubstantial humans.