Simple Acid Digestion Procedure for the Determination of Total Mercury in Plankton by Cold Vapor Atomic Fluorescence Spectroscopy.

Plankton, at the bottom of the food web, play a central role in the entry of mercury into the aquatic biota. To investigate their role in mercury uptake, reliable analytical procedures for Hg analysis are highly sought. Wet digestion procedures for determining total mercury in different biological matrices have been established since years, however only few studies focused on planktonic samples. In the present work, a simple and cost-effective wet digestion method was developed for the determination of total mercury in samples of small plankton material using a cold vapor atomic fluorescence spectroscopy (CVAFS). The optimization of the digestion method was achieved by using glass vessels with Teflon caps, low amount of acids (3 mL w/w 65% HNO3 or 3 mL 50% v/v HNO3), a constant temperature of 85 °C, the presence and absence of pre-ultrasound treatment, and a continuous digestion period (12 h). Certified reference materials IAEA-450 (unicellular alga Scenedesmus obliquus) and BRC-414 (plankton matrix) were used to optimize and validate the digestion method. The recovery efficiency of the proposed method for IAEA-450 and BCR-414 (3.1 mg and 21.5 mg) ranged between 94.1 ± 7.6% and 97.2 ± 4.6%. The method displayed a good recovery efficiency and precision for plankton matrices of low size. Thus, allowing better digestion of planktonic samples for mercury analysis using CVAFS techniques.

The Response of Estuarine Ammonia-Oxidizing Communities to Constant and Fluctuating Salinity Regimes.

Aerobic nitrification is a fundamental nitrogen biogeochemical process that links the oxidation of ammonia to the removal of fixed nitrogen in eutrophicated water bodies. However, in estuarine environments there is an enormous variability of water physicochemical parameters that can affect the ammonia oxidation biological process. For instance, it is known that salinity can affect nitrification performance, yet there is still a lack of information on the ammonia-oxidizing communities behavior facing daily salinity fluctuations. In this work, laboratory experiments using upstream and downstream estuarine sediments were performed to address this missing gap by comparing the effect of daily salinity fluctuations with constant salinity on the activity and diversity of ammonia-oxidizing microorganisms (AOM). Activity and composition of AOM were assessed, respectively by using nitrogen stable isotope technique and 16S rRNA gene metabarcoding analysis. Nitrification activity was negatively affected by daily salinity fluctuations in upstream sediments while no effect was observed in downstream sediments. Constant salinity regime showed clearly higher rates of nitrification in upstream sediments while a similar nitrification performance between the two salinity regimes was registered in the downstream sediments. Results also indicated that daily salinity fluctuation regime had a negative effect on both ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) community's diversity. Phylogenetically, the estuarine downstream AOM were dominated by AOA (0.92-2.09%) followed by NOB (0.99-2%), and then AOB (0.2-0.32%); whereas NOB dominated estuarine upstream sediment samples (1.4-9.5%), followed by AOA (0.27-0.51%) and AOB (0.01-0.23%). Analysis of variance identified the spatial difference between samples (downstream and upstream) as the main drivers of AOA and AOB diversity. Our study indicates that benthic AOM inhabiting different estuarine sites presented distinct plasticity toward the salinity regimes tested. These findings help to improve our understanding in the dynamics of the nitrogen cycle of estuarine systems by showing the resilience and consequently the impact of different salinity regimes on the diversity and activity of ammonia oxidizer communities.

More than just numbers: Suicide rates and the economic cycle in Portugal (1910-2013).

Suicides are a major concern for public health first and foremost because they are an avoidable cause of death. Moreover, they can be an indicator of self-reported emotional satisfaction and a good marker of overall well-being. In this study we examine how different economic and social aspects affected Portuguese suicide rates for more than one hundred years (1910-2013). We place this exercise in the specific historical context of the XX and early XXI century in Portugal, emphasizing the role of economic recessions and expansions. Controlling for aspects like wars, health care availability, political instability, and demographic changes, we find a strong association between a decline in the growth rate of real output and an increase in suicide rates for the whole population. In this regard, while male suicide rates are non-negligibly influenced by economic downturns, female suicide rates are in general more responsive to a more open political and economic environment. Our results are robust if we consider the mid-term cyclical relationship. Our findings advocate that, during recessions, public health responses should be seen as a crucial component of suicide prevention.

A prevalencia de lombalgia em capoeiristas do Rio de Janeiro / Low back pain prevalence in capoeira athletes in Rio de Janeiro

Varios autores,desde tempos remotos,vem estudando a lombalgia,afecçao mais comum na populaçao mundial.De acordo com pesquisadores especializados,o seu diagnostico é dificil devido a inumeros fatores;entre eles,trauma mecanicos, caracteristicas psicossociais e comportamentais,tipo de ocupaçao,tipo e local da atividade fisica,os quais podem levar a uma disfunçao ou algia na regiao lombar.A pratica da capoeira abrange pessoas de todas as idades,sexos e classes sociais.Com a expansao do numaro de locais onde se ensina capoeira,cresce a quantidade de professores e de praticantes deste desportos.Varios professores nao possuem,porem,conhecimento necessario á sua funçao,podendo,induzir o aluno a executar determinadas tarefas capazes de gerar lesoes.O objetivo do presente estudo é levantar a prevalencia de dor lombar em capoeiristas do Rio de Janeiro.Para tal foi utilizado em questionario epidemiologico,auto-aplicavel adaptado do Quebec Back Pain Disability Scale,enfatizando perguntas sobre a dor lombar e indagando:idade,estado civil,ocupaçao e a descroçao da atividade fisisca do participante.Tem-se como preocupaçao fazer um levantamento dos fatores predisponentes á dor e aos aspectos da lombalgia,para que no futuro,seja possivel promover-se a elaboraçao de um programa de educaçao para a saude.Este questionario foi aplicado em 145 capoeiras com idade de 26,7 + - 11,2 anos da cidade do Rio Janeiro.Empregou-se tanto as tecnicas da estatisticas descritiva,no sentido de caracterizar os dados medios das respectivas variaveis,quanto as tabelas de frequencia,alem das tecnicas inferencial,por meio de um teste nao parametrico qui-quadrado,a fim de verificar-se a interdependencia entre as distribuiçoes de frequencias observadas,para uma significancia de p nemor0,05.Os dados achados apontam para as seguintes caracteristicas:a prevalencia de dor lombar atingiu 36,6,e é pois,mais frequente no sexo feminino(p=0,01),em atletas que ja sofreram lesoes durante a pratica(p=0,024),acidentes/doença que envolvessem a regiao lombar(p=0,024) e a regiao do joelho (=0,015).Observa-se tambem frequencia mais elevada em capoeiristas com dor cervical (p=0,018) e dor no ombro(p=0,003).Nas demais questoes,esta variavel nao apresentou relaçao de dependencia significativa( menor0,05).