Banca de DEFESA: ANGELA NETA DIAS DOS SANTOS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : ANGELA NETA DIAS DOS SANTOS
DATA : 26/10/2018
HORA: 14:00
LOCAL: Laboratório de Biogeoquímica Ambiental, Bloco IQ - Campus José Ribeiro Filho
TÍTULO:

SURVEY OF MERCURY CONCENTRATIONS IN AQUATIC BIRDS OF THE MADEIRA RIVER BASIN, WESTERN AMAZON

PALAVRAS-CHAVES:

Key words: Waterfowl, mercury, methylmercury, Amazon.

PÁGINAS: 78
GRANDE ÁREA: Ciências Biológicas
ÁREA: Ecologia
SUBÁREA: Ecologia de Ecossistemas
RESUMO:

Mercury (Hg), in its most toxic chemical form, methylated, is readily bioaccumulated by aquatic organisms through trophic exposure. In the last century, the Madeira River suffered an intense release of Hg (metallic phase) to the environment, in the process of gold mining. Even with the reduction of this activity, concentrations of Hg in the aquatic environment continue to be maintained. The birds, because they occupy high trophic position, have been used as sentinels of environmental contamination by Hg. This study aimed to determine if the concentrations of Hg between the different species of birds vary according to their eating habits, gender and age. In this study, a colony of aquatic birds was found located in a riverine community in the municipality of Humaitá (AM), which was determined as the study area. Samples of feathers and internal tissues of the species E. thulla, A. cocoi, A. alba, C. cochlearius, N. brasilianus, A. anhinga, C. atratus, P. simplex and C. rupestres were collected. All tissues collected (muscle, liver, kidney, brain and feathers) were previously prepared in the laboratory for the determination of total Hg (THg), only the feather samples were also quantified for methyl mercury (MeHg). The P. simplex had the highest mean concentration of THg in feathers (12.810 mg.kg^-1). C. atratus presented the second highest mean THg in feathers (9.933 mg.kg^-1). Among the Ardeidae species, C. cochlearius presented the highest average THg concentration (4.930 mg.kg^-1). A. cocoi was the second highest concentration of mercury in feathers (4.036 mg.kg^-1), followed by E. thulla (3.943 mg.kg^-1) and A. alba (3.813 mg.kg^-1). The species A. anhinga and N. brasilianus presented a mean of 3.690 mg.kg^-1and 2.915 mg.kg^-1, respectively. Finally, with the lowest mean THg in the feathers was C. rupestres, with a mean of 0.898 mg.kg^-1. The wide variation in the concentrations of mercury in birds is associated, mainly to the differences in the diets of the species and the strategy of foraging. When we compared the percentage of MeHg present in the feathers of the species, we observed that there was a high significant difference between C. atratos and A. alba. Thus, as well as between the species A. cocoi and A. alba. The species E. thulla, presented low significant difference for the species N. brasilianus, C. atratus, A. cocoi and A. anhinga. This difference also occurred between the species N. brasilianus and A. alba. In the other species, there was no significant difference. As expected, the pen presented the highest mean THg concentration (5.078 mg.kg^-1). The liver, in comparison with the other internal tissues, had the highest concentration of THg (0.757 mg.kg^-1). Subsequently, the kidney had the third highest mean at concentrations of THg (0.382 mg.kg^-1). The lung had a mean of 0.339 mg.kg^-1and the heart 0.299 mg.kg^-1. Already for the muscle was 0.235 mg.kg^-1. The blood presented a mean of 0.229 mg.kg^-1and the brain of 0.118 mg.kg^-1. Regarding the age, in this study there was no difference in relation to the young and adults for the levels of THg and MeHg concentrations. However, when we compare the percentage of MeHg that these individuals are eliminating by means of feathers, we observed a significant difference between these groups, indicating that adult individuals are eliminating greater concentration of MeHg by feathers. However, this study showed that individuals occupying the highest trophic level are subject to increased exposure to food-borne Hg contamination. In this way, waterfowl are considered good indicators of environmental contamination by mercury. In addition, feathers and blood can be considered good matrices for the determination of mercury in the environment, since both are methodologies that do not need to sacrifice the animal for the collection of samples.

MEMBROS DA BANCA:
Presidente - 359961 - WANDERLEY RODRIGUES BASTOS
Interno - 1348799 - MARIANGELA SOARES DE AZEVEDO
Interno - 1632974 - ANGELO GILBERTO MANZATTO
Externo à Instituição - DARIO PIRES DE CARVALHO - UFRJ