Eduardo Duarte Marques

First assessment of trace metal concentration in mangrove crab eggs and other tissues, SE Brazil

The mangrove crab Ucides cordatus is widespread in the Brazilian coast, which has an important role in nutrient cycling. This species reproduces in summer and females carry eggs about a month, when they maintain contact with water and sediments. It remains unclear if trace metals can be absorbed or adsorbed by the eggs during development. The present study aims to investigate, for the first time, trace metal concentrations in ovigerous female tissues and eggs of U. cordatus in two areas with different metal pollution levels in the Southeastern Brazil. Samples were collected in two different mangroves, Guanabara Bay (GB) highly polluted environment and Paraíba do Sul River (PSR). In both populations, we observed significant increase of V, Cr, and Mn concentrations along eggs maturation. The higher metals averages were found in PSR population. This trend was reported since the 1990s and lower concentrations in GB marine organisms were attributed to reducing conditions, high organic load, and the presence of sulfide ions. These conditions restrict the bioavailability of metals in the bay, with exception of Mn. No significant differences were observed in gills and muscles. In both populations of the present study, V, Zn, As, and Pb were higher in eggs of initial stage, whereas Mn, Ni, Cu, and Cd were higher in hepatopancreas. Beside this, V, Cr, Mn, As, and Pb showed an increase concerning egg development. Thus, V, As, and Pb in eggs come from two sources previous discussed: females and environment. Zinc came mainly from females due to essential function. Those new information should be considered as one of the mechanisms of trace metal transfer to the trophic chain, between benthonic and pelagic environment.

Seasonal variations of water quality in a highly populated drainage basin, SE Brazil: water chemistry assessment and geochemical modeling approaches

The São João Drainage Basin is a very important and strategic waterbody located in the Lagos Region, Rio de Janeiro State, one of the most popular tourist regions of Brazil. However, the fast economic and subsequent population growth in that region has created untreated wastes from several anthropogenic activities, which include the trace metals disposal into the surface waterbody. This study aims to relate the major ions and trace metals behavior during a 1-year sampling campaign and to provide information about the sources of chemical constituents and the factors that control their concentrations in the three main fluvial compartments of the drainage basin, including the Juturnaíba Reservoir which has a crucial role for water supply in the Lagos Region. The chemical data reveal that rainfall is the main factor responsible for the physicochemical parameters and the water dissolved constituent’s variations. The geological and anthropogenic factors which are the main sources of water constituents were assessed by the Inorganic Chemical Index. Those data corroborate the great influence of rainfall and reveal the importance of anthropogenic sources of chemical constituents in some parts of the Juturnaíba Reservoir. The geochemical modeling suggests that hydrolysis reactions are primarily responsible for the trace metals availability in the three fluvial compartments in both dry and wet seasons, followed by carbonate and sulfate complexation.

Mercury bioaccumulation in fishes of a paddy field in Southern of Brazil

Aim: The aim of present study was to evaluate the Hg concentration in two species of fish (Astyanax sp and Corydoras paleatus) and its potential use as a biomonitor, in order to know if the use of pesticides and fertilizers in paddy can enhance the Hg contamination to adjacent aquatic environment.MethodsSoil, suspended particulate matter and fish samples were sampled in a paddy field in South Brazil. A cold vapor system, coupled with a GBC 932 atomic absorption spectrophotometer was used for total Hg determinations in samples.ResultsThe paddy soil shows Hg concentration 2-fold higher (mean 31 ng g-1) in comparison to background areas (not cultivated). Suspended particle matter Hg concentration in paddy channels (mean 232.5 ± 44.2 ng g–1) are 1.5 times higher than the regional background. The analyzed fish specimens Astyanax sp in paddy showed Hg concentration 4-fold higher and significant different to background area. The mean Hg concentration in fish was: 51.7 ± 19.5 ng g–1 in Astyanax sp and 156.8 ± 44.0 ng g–1 in Corydoras paleatus.ConclusionsConsidering the linear regression and Man whitney test hypothesis to Hg concentration in fish tissue from paddy suggests that Astyanax sp. can be a good biomonitor of Hg contamination, whereas Corydoras paleatus is a potential biomonitor. However, more studies with Corydoras are necessary in order to aggregate consistency to this hypothesis.

Hydrogeochemical Control and Dissolved Load Origin of Surface Water from São João River Drainage Basin: Seasonal Variations Approach

A bacia de drenagem do rio Sao Joao possui um papel importante e estrategico para a Regiao dos Lagos, Estado do Rio de Janeiro, uma das regioes turisticas mais importantes do Brasil. Entretanto, o rapido crescimento economico e o subsequente crescimento populacional na regiao geram impactos atraves das atividades antropogenicas, os quais incluem a contaminacao por metais tracos na agua superficial. O presente estudo tem por objetivo relatar o comportamento dos ions maiores e metais tracos ao longo de uma campanha de amostragem de um ano, fornecendo informacoes sobre as suas principais fontes e controle geoquimico nos tres principais compartimentos fluviais da bacia de drenagem. Os dados obtidos revelam que a pluviosidade e a principal responsavel pela variacao dos parâmetros quimicos e dos constituintes dissolvidos da agua. As contribuicoes geologicas e antropogenicas, as quais sao as principais fontes para a carga dissolvida na agua, foram analisadas pelo Indice de Quimica Inorgânica (IQI). Esses resultados corroboram a grande influencia da pluviosidade e revela a contribuicao antropogenica em algumas partes do reservatorio de Juturnaiba.

Riscos de ingestão de flúor: estudo de caso para água mineral do interior do estado do Rio de Janeiro

O consumo de fluor presente em aguas superficiais e subterrâneas e umapratica comum em diversos paises. Alem de abordar a tematica controversaquanto ao consumo do fluor, este artigo apresenta um estudo de caso deavaliacao de risco a saude humana pelo consumo de aguas fluoretadas,provenientes do Parque de Aguas Minerais, localizado na regiao Centro-Suldo Estado do Rio de Janeiro. As concentracoes de fluor foram medidas entreoutubro de 2014 e agosto de 2015 em tres pocos de agua mineral e emseus respectivos fontanarios, sendo as fontes denominadas popularmentede Fonte Alcalina Terrosa Calcica, Alcalina Terrosa Ferruginosa e AlcalinaTerrosa Magnesiana. Foi avaliada a possibilidade de haver riscos para odesenvolvimento de fluoroses e aumento de fraturas osseas nas populacoesconsumidoras. Esta pesquisa modelou a ingestao diaria dessas aguascom fluor por receptores residenciais dos tipos: bebes, infantes, criancas,adolescentes e adultos. Foi constatado que os grupos de bebes e infantespodem estar mais sujeitos a riscos cronicos para o desenvolvimento defluorose dentaria na fonte de agua mineral Alcalina Terrosa Magnesiana.Recomenda-se que a agua mineral dessa fonte nao seja consumida pelosgrupos de criancas.