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210Pb geochronologies of Cd, Cu, Hg, and Pb fluxes were obtained from the intertidal mudflat sediments of the coastal lagoons Chiricahueto, Estero de UrIas, and Ohuira in the Mexican Pacific. The Cu and Hg sediment concentrations at the three lagoons fell within the ranges of 6-76 μg g-1 and 0.1 to 592 ng g-1, respectively; Chiricahueto and Esterb de UrIas sediments had comparable Cd and Pb concentrations within the ranges of 0.2-2.1 μg g-1 and 10-67 μg g-1, respectively; whereas in Ohuira lagoon, Cd concentrations were lower (0.1-0.5 μg g-1) and Pb concentrations were higher (115- 180 μg g-1) than in the other lagoons. The metal fluxes (μg cm-2 y-1) for the three lagoons fell within the ranges of 0.02-0.15 for Cd, 0.7-6.0 for Cu, 0.001-0.045 for Hg, and 0.7-20 for Pb. The Hg pollution in Estero de Urlas was attributed to the exhausts of the thenrioelectric plant of Mazatlan and the metal enrichment in Chiricahueto and Ohuira was related to the agrochemical wastes from the croplands surrounding these lagoons. [ABSTRACT FROM AUTHOR]

Hg was analyzed in seven tissues of 52 common shoveler Anas clypeata collected from the coast of SE Gulf of California. Mean Hg concentrations were highest in the liver (2,885 ng g⁻¹) and lowest in the gizzard (621 ng g⁻¹); they followed the order: liver, feathers > muscle tissue and tissues of the circulatory system > digestive organs. Hg levels were similar or higher than birds of the same trophic level and feeding habits. Considering the relationships of Hg among tissues and blood we recommend the use of blood as an efficient method to monitor Hg.