accumulation mercury in (larus cachinnans) in bandar mahshar and shadegan

introduction despite the limited anthropogenic activity in arctic regions, the levels of heavy metals are of concern and the arctic is considered as an important global sink for mercury depletion. mercury is not readily available to the food web in its natural form. however, inorganic mercury are converted to organic mercury compounds by microbial processes of anaerobic organisms. mehg is more lipophilic, highly bioaccumulative and the most toxic form of mercury . the stablishment of  industrial  in the coastal zone resulted in producing and realsiay of various types of contanius in to the marine enviromental the neighbor hoad of khormusa to bandar mahshar petrochemical complex could be poteutialy harm ful for marine ecosystem interms of hg pollution.birds are often the most numerous representatives of vertebrates in polar and subpolar regions making them ideal bioindicators of pollution. marine birds are exposed to a wide range of trophic levels, and those at the top of the food chain are susceptible to bioaccumulation of pollutants.  mercury in the marine environment in order to understand the extant of hg contamination in the marine environment and its health. seabirds are useful as bioindicators of coastal and marine pollution. marine birds, defined as birds that spend a significant proportion of their life in coastal or marine environments, are exposed to a wide range of chemicals because most occupy higher trophic levels making them susceptible to bioaccumulation of pollutants. since different families, have different life history strategies and cycles, behavior and physiology, diet, and habitat uses, their vulnerability varies. further, the relative proportion of time marine birds spend near shore, compared to pelagic environments, influences their exposure. biomonitoring studies are necessary .due to long living, staying at the top of food chain, availability and large number of yellow-legged (larus cachinnans) in mahshahr area. gull yellow leg of seabirds around the world, including europe, africa, asia and the pacific are found. methyl mercury due to its great affinity to high affinity for fat and protein rail sulfide groups in the food chain is transmitted rapidly and accumulate in organisms. in areas where fish and other marine products food group constitutes a major source of organic mercury bioaccumulation of mercury in human tissues. this study was carried out to study the level of mercury accumulation in yellow gull and the amount of mercury witch is transter to the apper trophic level in mahshar area. since birds are fed high levels of the food chain, they are often known ecology, material and methods gull yellow (larus cachinnans) were collected from the khormusa and bandar mahshar.the collection gull yellow (n=18). samples were brought to the laboratory right away, birds were dissected immediately. liver, breast feather, kiendy, musel, heart, bone and skin were removed the bodies of the speciments. feather were washed in deionized water alternated to removed loosely adherent external contamination. all sample were wrapped in aluminium foil and stored at minimum -20ºc.the seabirds were weighed and size measured.all sample were dried in a 50 ºc oven.the biological sample were digested by a mixture of nitric acid and patacium permangenat in a closed aqueous system in a hot plate.after pressure digestion, the biological sample waz supplied with stannous chloride and hydrochloric acid to reduce the hg in a sample to atomic hg.mercury was measured by atomic absorption cold vapour (aas). the statistical analysis was carried out using spss soft ware version 16. the data were normality using a kolmogorov-smirnov test. mercury concentration in samples were test for mean differences among species using one-way analysis of variance (anova). when significant differences were observed among the species and tissus, tuky-kramer test was applied to determine which means were significantly different. values are given as mean± standard errors and we considered a p value ˂0.05 to be statistically significant. discussion of results & conclusions in both sexes the maximum hg concentration were measured in feather(9.70±1.16 µ/g in female and 8.27±.32 µ/g in male). the minimum hg concentration were observed heart muscle(.42±.03 in female and .43±.01 µ/g in male).. a significant and positive correlation found between hg concentration in feather or liver and total weight of the birds (p˂0.05). the maximum hg concentration was found in the feathers either in male and females. while the minimum hg concentration was found in heart muscle. a significant difference was found between male and females in terms of hg concentration in feather and liver(fig 1) . many studies have pointed out that hg have to accumulate in birds feathers.it is suggested that feather and liver could serves as suitable bimonitor agent for hg a yellow leg gull. there waz no significant difference between hg concentration in the birds belonging to different stations. this was true for both male and female birds (fig 2).althogh the studies stations are far from each other it is suggested that birds from both stations have a same feeding ground.       figure 1- concentration hg in yellow gulls( male and female) in mahsahr       figure 2- concentration hg in yellow gulls( male and female) in aboukhozayer many seabirds can fly in long distance. therefore it is possible that mahshar and shadegan gulls gather in the same feeding ground to feed. comparision between hg concentration in different tissues of yello legged gull in this study (tabel1) with some other birds from other parts of the world deuonstrated that yellow legged in this study accumulated. highe concentration of hg in it tissue. this finding alarms that controlling and managing action are require to pollution in the mahshar area. significant correlation was observed between hg concentration in different tissues and total body weight of the birds.the correlation coefficient was higher in the case of feather(fig 3).     fig 3-corralation between feathers and weight yellow gulls    genrally most of the hg body burdent accumulation in feathers and the contain proteins rich of sulfur amino acid. it is suggested yellow-legged is appropriate agent for hg biomonitoring in bandar mahshahr and it is feather is the most suitable tissue for hg monitoring. also compare our results with standard world health organization, found that mercury levels in yellow-legged above mentioned standards.