Assessment of mercury methylation and methylmercury demethylation potentials in water and sediments along the Wabigoon River system.

Monomethylmercury (MMHg) plays a crucial role in the accumulation of mercury (Hg) within aquatic food chains. Since ambient levels of methylmercury are governed by the balance of simultaneous methylation and demethylation processes, determining in situ methylation and demethylation rates is critically important to understand the dynamics of methylmercury in the environment. This is especially important in the Wabigoon River system in Ontario, Canada, which is severely contaminated with Hg by a chlor-alkali facility operating in the 1960s, and still exhibits some of the highest recorded fish mercury concentrations in Canada. This work used a simultaneous addition of isotope enriched Hg and MMHg tracers to ascertain Hg methylation and MMHg demethylation potentials. At the locations investigated for this study, the most favourable conditions for Hg methylation were found at the Hydroelectric dam, being able to transform 4.2 % and 4.4 % of added Hg in water and sediments per day, respectively, to MMHg. This could correspond to 1.9 ng/L and 29 ng/g of new MMHg being produced from current ambient Hg. Clay Lake, which is considered a sink for mercury and exhibiting a seasonal anoxic environment at its bottom waters, also demonstrated significant MMHg generation, being able to produce 2.7 ng/L and 13 ng/g of MMHg per day, respectively. Demethylation rates in sediments of riverbed and wetland locations showed an average half-life for methylmercury of 2.1 days, indicating a rapid turnover of MMHg in the Wabigoon River. However, significantly lower demethylation rates were also measured near the inflow of Clay Lake, where it took up to 144 days for MMHg to decrease by 50 %. Generally, most of the investigated locations downstream of the pollution source displayed the potential to generate methylmercury, which could be distributed throughout the Wabigoon River system and therefore require attention with respect to future remediation activities.

Ancestry of victims of 1755 Lisbon earthquake based on tooth morphology.

The present investigation comprises the characterization of skeletal remains recovered from the 2004 archaeological excavations carried out in the Cloister's Southwest Wing of the Academy of Sciences of Lisbon, attributed to the 1755 earthquake. Among the remains, many teeth were found. Our goal is to use dental morphological characteristics to assess the geographic ancestry of the combined sample using the methods of biodistance and web-based application of the Arizona State University Dental Anthropology System 2. The crown and root traits of the ASUDAS were scored in a sample of 1068 disarticulated teeth, 65 skulls, 138 adult and 42 sub-adult jaws. Eight characteristics of 34 specimens (7 skulls and 27 jaws) were analyzed using rASUDAS2. Results demonstrate that 73.5% of this sample can be assigned to Western Eurasian ancestry, with the remaining 26.5% divided between Sub-Saharan Africa, non-Arctic and Arctic America, and East Asia. Euclidean and Bray-Curtis distance measures were used to put this Portuguese sample in a world context. From both distance matrixes, cluster analyses were used to generate dendrograms. Based on Bray-Curtis values, Portugal is closest to Western Europe, followed by India and Eastern Europe. For the tree based on Euclidean distances, India is the first to join Portugal, followed by Eastern and Western Europe. Therefore, on both an individual and group level, the Portuguese sample is most closely tied to Western Eurasia. However, there may be other ancestries in the sample, such as Sub-Saharan Africa, due to non-European migrants in Portugal along with the African slave trade to Brazil that reached its peak in 18th century Lisbon.

Mercury methylation rates in Deception Island (Maritime Antarctica) waters and pyroclastic gravel impacted by volcanic mercury.

Deception Island is an active volcano in the Antarctica being volcanism a source of mercury. To improve the understanding of the Hg cycle in this remote ecosystem, pyroclastic gravel and water samples were collected and total (THg) and monomethylmercury (MMHg) concentrations were measured as well as the potential for Hg methylation. Gravel samples collected close to active fumaroles showed the highest THg levels (72 ng/g) while in water samples the highest concentrations of THg (1.2 ng/L) and MMHg (0.45 ng/L) where found. Methylation activity was barely observable in gravel samples. Biotic methylation rates in water were up to 13 times higher compared to those recorded previously in other polar waters. Abiotic methylation processes also play an important role, with up to 0.54 ± 0.43% of added Hg converted instantaneously to MMHg. These results suggest that Deception Island presents favourable conditions for MMHg explaining the elevated concentrations of both THg and MMHg in this ecosystem.

Avaliação do Conhecimento de Médicos Professores, Residentes e Estudantes de Medicina acerca da Declaração de Óbito / Evaluation of the Knowledge of Medical Professors, Residents, and Medical Students regarding Death Certificate

RESUMO A Declaração de Óbito (DO) é o documento-base do Sistema de Informações sobre Mortalidade, do Ministério da Saúde. Contudo, trata-se de um assunto pouco abordado na formação médica continuada. O objetivo deste trabalho é avaliar o nível de conhecimento sobre questões básicas e de ordem prática no preenchimento e emissão da DO em alunos do 12º período do curso médico da Universidade Federal do Rio Grande do Norte (UFRN), em médicos residentes e em médicos docentes do Complexo Hospitalar da UFRN. Foram aplicados questionários com 11 questões de mútipla escolha, elaborado de acordo com o Manual de Preenchimento de Declaração de Óbito. Participaram da pesquisa 45 alunos, 66 médicos residentes e 96 médicos professores. Os médicos residentes obtiveram a melhor média de acerto entre as categorias. Nenhuma das três categorias obteve média de acertos de 70%. Considerando o tempo de formação em relação ao número de acertos, observou-se que, para cada ano de formação, em média, a porcentagem de acerto diminui em 0,485%. Este estudo evidencia a importância de uma educação médica continuada nas faculdades de Medicina para um adequado preenchimento e emissão da DO.

ABSTRACT The death certificate is the base document for the Ministry of Health’s Mortality Information System. However, this is a subject rarely addressed in continuing medical education. The objective of this study is to assess the knowledge about basic and practical issues in completing and issuing death certificates among 6th year medical students from UFRN, residents and medical professors from the UFRN Hospital Complex. A questionnaire was used containing eleven multiple choice questions, prepared in accordance with the Death Certificate Completion Manual. 45 students, 66 medical residents and 96 medical professors participated in the study. The residents obtained the highest average score of the three groups. None of the groups obtained a mean score of 70%. Considering the amount of training in relation to the number of correct answers, it was observed that for each year of training, the success rate decreased by 0.485%. This study highlights the importance of continuing medical education in medical schools for proper completion and issuance of death certificates.