Water quality assessment and geochemical processes in the unconfined coastal Boa Viagem Aquifer, Recife, NE Brazil

A hydrochemical study was conducted on the Quaternary Aquifer, in Recife, Brazil. Groundwater samples were collected in March–April 2015, at the beginning of the rainy season. Conventional graphics, ionic ratios, saturation indices, GIS mapping, and geostatistical and multivariate statistical analyses were used to water quality assessment and to characterize the main hydrochemical processes controlling groundwater’s chemistry. Q-mode hierarchical cluster analysis separated the samples into three clusters and five sub-clusters according to their hydrochemical similarities and facies. Principal Component Analysis (PCA) was employed to the studied groundwater samples where a three-factor model explains 80% of the total variation within the dataset. The PCA results revealed the influence of seawater intrusion, water-rock interaction, and nitrate contamination. The physico-chemical parameters of ~30% groundwaters exceed the World Health Organization (WHO) guidelines for drinking water quality. Nitrate was found at a concentration >10 mg NO3−/L in ~21% of the wells and exceeded WHO reference values in one. The integrated approach indicates the occurrence of the main major hydrogeochemical processes occurring in the shallow marine to alluvial aquifer as follow: 1) progressive freshening of remaining paleo-seawater accompanying cation exchange on fine sediments, 2) water-rock interaction (i.e., dissolution of silicates), and 3) point and diffuse wastewater contamination, and sulfate dissolution. This study successfully highlights the use of classical geochemical methods, GIS techniques, and multivariate statistical analyses (hierarchical cluster and principal component analyses) as complementary tools to understand hydrogeochemical processes and their influence on groundwater quality status to management actions, which could be used in similar alluvial coastal aquifers.

Potential Eutrophication Associated with Phosphorus Inputs from Shrimp Effluents in a Tropical Estuary

Shrimp farming has been associated with eutrophication due to the generation of effluents enriched with organic matter and nutrients. Phosphorus (P) distribution was investigated in the Coreaú River Estuary (NE Brazil) using surface sediments and sediment cores. In surface sediments, total P concentrations ranged from 349.2 to 633.5 μg g-1 (mean = 465.2) and were about three times lower than those of other Brazilian estuaries impacted by larger shrimp cultures. The predominance of P forms in surface sediments followed the sequence: iron-bound P (Fe-P, 30%) > organic-P (Org-P, 23%) > exchangeable-P (Exch-P, 20%) > authigenic apatite (Ca-P, 15%) > detrital apatite (De-P, 12%). No significant correlation was observed between Exch-P and Fe-P (r = 0.389; p < 0.05). Highest Exch-P and Org-P concentrations and a strong correlation between these forms were found (r = 0.706, p < 0.05), suggesting the same sources of P and organic matter. Total P accumulation along the cores was 10,211 and 15,632 μg g-1 at the estuary mouth (T1) and the upper estuary (T2), respectively. T1 exhibited the predominant sequence: De-P (36%) > Ca-P (25%) > Fe-P (22%) > Exch-P (9%) > Org-P (7%); whereas T2 showed: Fe-P (31%) > De-P (23%) > Org-P (21%) > Ca-P (17%) > Exch-P (9%). Phosphorus depositional history points to P accumulation episodes at the end of the 1980 and mid-1990, coinciding with increasing urbanization and the beginning or maximum activity of the shrimp farms. Despite the low total P concentrations, the proportions of the labile forms Exch-P, Fe-P and Org-P in surface sediments indicated a trend to a high potential for eutrophication.

Contamination in newly hatched larvae of the mangrove crab Ucides cordatus and a new perspective about trace elements transport

Mangroves are relevant ecosystems due to their ecological role, economic use, and social importance. One of the most abundant and important species in Brazilian mangroves is the exploited crab Ucides cordatus. This study focuses on this species and the aim was to evaluate the concentration of trace elements in the hepatopancreas of ovigerous females, eggs (pre-hatching and hatching stages), and for the first time, in newly hatched larvae. Ovigerous females were captured in two Southeastern Brazil mangroves (Guanabara Bay and Paraíba do Sul River’s secondary estuary) and spawning was held in spawning tanks, in the laboratory. Some females were not taken to the tanks, but they were frozen right after collection. There was no significant difference in trace element concentration between these females and those kept in the spawning tanks. Both essential and non-essential trace elements were detected in newly hatched larvae. Comparing with the adult female, the elements Zn, Cu, and Mn showed the highest concentrations in larvae and eggs. Vanadium, Cr, and Mn concentrations were significantly higher in hatching eggs than observed in newly hatched larvae, indicating the retention of elements in the eggshell. Considering the V (0.17 - 1.17 μg.g−1 dry weight), Cu (14.1 - 41.1 μg.g−1 dry weight), and Zn (235.4 - 263.9 μg.g−1 dry weight) concentrations in newly hatched larvae, with the same order of magnitude observed in suspended particulate matter (SPM) and sediments in suspension, the planktonic larval dispersion could result in the transport of elements beyond the mangrove, and their introduction in coastal waters.

Metal bioavailability and distribution in the fish community in a tropical estuary, Sepetiba Bay, Rio de Janeiro, Brazil

Sepetiba Bay has a wealth of fish species (total 148) as well as a vast area of mangroves and numerous rocky islands, which are important sites of reproduction for marine life. This peculiar environment of the Brazilian coast hosts one of the most important industrial centres of south-eastern Brazil. This site has been impacted for decades by the release of industrial emissions and effluents with high metal loads by the steel industry. The ranges of metal concentrations in fish muscle from the species Micropogonias furnieri, Genidens genidens, Cathorops spixii, Notarius grandicassis, Diapterus rhombeus, Selene vomer, Prionotus punctatus, Citharichthys spilopterus, Achirus lineatus, Trinectes paulistanus, Symphurus tessellatus and Hypanus guttatus were measured (Al: 0.02-555.9 µg g-1 d.w., As: 0.0002-20.1 µg g-1 d.w., Cd: <0.0002-0.2 µg g-1 d.w., Cu: 0.2-2.3 µg g-1 d.w., Fe: <0.02-244.9 µg g-1 d.w., Zn: 0.5-227.3 µg g-1 d.w. and Pb: <0.001-1.3 µg g-1 d.w.). The Kruskal-Wallis test revealed significant differences (p<0.05) in the As, Cu, Fe, Pb and Zn contents among fish species. The monitoring of suspended particulate matter during dredging operation revealed the mean metal values for Al (6059±6268 µg g-1), Cd (0.2±0.5 µg g-1), Cu (29±29 µg g-1), Zn (332±892 µg g-1), and Pb (52±70 µg g-1). The results of bioaccumulation in fish calculated from the bioavailable sediment fractions and suspended particulate matter showed lower values than those in fish muscle. Arsenic was found at levels above the maximum limit for human consumption according to Brazilian legislation. However, the estimated probability and risk of metal intake via fish consumption showed that the consumption of all species presented low risk.

Análise geoquímica das águas subterrâneas no município de Boquira, no semiárido baiano - Brasil

The geochemical analysis was carried out in the center-south portion of the state of Bahia, in the semi-arid region of Bahia, where outcrop the Paramirim Complex, Boquira Unit, Boquira Granite, Veredinha Granite, Serra do Espinhaço, detritus coverings and alluvial deposits. The Boquira Unit is known for lead-zinc mineralization. In this unit operated the Boquira mine, considered the largest lead and zinc mine in Brazil, until it was suddenly abandoned, leaving significant environmental liabilities of toxic metals such as lead, zinc, silver, barium, copper, chromium and nickel. To characterize the groundwater 16 physical-chemical parameters from 24 wells were used, obtained from the Water and Sanitation Engineering Company of Bahia - CERB. Its classification was made in the Piper Diagram and the ionic relations in meq/L. To evaluate the quality of the water we used the Consolidation Ordinance no 5/2017 of the Ministry of Health and World Health Organization. With the PHREEQC 3.5 hydrochemical model, the saturation index of the analyzed elements was calculated. The results showed predominance of calcium chloride waters (71% of the samples), with ionic relations of type rCa2+> rMg2+>rNa+ and rCl->rHCO3->rSO42+. Geochemical modeling indicated calcite (CaCO3), dolomite (CaMg(CO3)2) and quartz (SiO2) as the main minerals with a tendency to precipitation. The first two were associated with the dissolution of the Boquira Unit carbonates and the third one with the quartzites of the Serra do Espinhaço Formation. The concentrations of calcium and chloride showed 54% and 25% of the samples above the Maximum Allowable Value for human consumption, respectively, representing a risk factor to the health of the population in the area.

On the article “Weathered potassic volcanic rocks as protoliths of the hematitic phyllites of the southern Serra do Espinhaço (MinasGerais)”: a discussion

Chaves and Knauer (2020) have presented three new whole-rock chemical analyses of phyllitic hematite, a unique metamorphic rock of the southern Serra do Espinhaço. Based on their three samples and a selection of other three samples from the literature, Chaves and Knauer have proposed that the geochemical uniqueness of the rock – i.e., high contents of K2O, Al2O3 and Fe2O3, and depletion in SiO2 – would represent a weathered, feldspathoid-rich alkaline basalt. This contribution is a discussion of their new data, the trace-element contents of which are at odds with those of a potassic, mantle-derived volcanic protolith for the hematitic phyllite. Its Nb/Th ratios of ~3 and chondrite-normalised La/Yb ratios of ~9–17, for instance, are typical of the continental crust. We also point out aspects that escaped the attention of Chaves and Knauer (2020), one of which is the ubiquitous occurrence of tourmaline in the hematitic phyllite.

Vulcânicas potássicas intemperizadas como protólitos dos filitos hematíticos da Serra do Espinhaço Meridional (Minas Gerais)

The hematitic phyllite is a rock that occurs in the São João da Chapada and Sopa-Brumadinho formations of the southern Espinhaço range. Its origin is widely discussed in papers on Espinhaço, but there is no consensus on its protolith due to certain characteristics of the lithotype, such as its chemical composition and textural features. The pattern of rare earth elements strongly enriched [(La/Yb)N 6.80-17.68], with light rare earth elements [(La/Sm)N 2.54-4.83] richer than heavy ones [(Gd/Yb)N 1.28-3,32], suggests that the protolith was an alkaline volcanic rock formed during the rift that generated the Espinhaço basin. The major elements indicate that the alkaline rock met weathering processes, becoming a regolith. During the Brasiliano metamorphism, it finally became hematitic phyllite. Other characteristics of the lithotype, such as the presence of sericite-bearing rounded parts (possibly formed by alteration and deformation of leucite crystals) and the preservation of igneous layering, suggest a potassic volcanic origin for hematitic phyllite. In diagram that allows identifying altered and metamorphic volcanic rocks, the investigated samples have composition similar to a feldspathoid-rich alkali-basalt, probably a leucite tephrite, a leucitite or even a lamproite, rocks from mantle source.

Técnica de otimização aplicada a lâminas palinofaciológicas para o estudo dos folhelhos da Formação Irati

Na Formação Irati são encontrados folhelhos betuminosos do período Permiano com elevado conteúdo de matéria orgânica. O presente estudo propôs utilizar o banho ultrassônico (ultrassom) para provocar a dispersão das partículas orgânicas do querogênio para otimizar a montagem de lâminas palinofaciológicas e a análise de palinofácies desses folhelhos. Após isolamento do querogênio, uma alíquota de cada amostra foi separada para ser tratada em banho ultrassônico, na frequência 40KHz, por 30 segundos. Lâminas foram montadas com querogênio com e sem tratamento no ultrassom. Em microscópio, 100 itens foram contabilizados em cada lâmina. Ao serem comparados os resultados da análise de palinofácies nas lâminas com e sem tratamento foi possível verificar que não houve diferenças na contabilização dos itens, porém houve uma diferença importante na composição dos constituintes orgânicos, provavelmente devido à redução significativa de aglomerados após o tratamento, permitindo a visualização de outros itens além da matéria orgânica amorfa.

Avaliação geoquímica da influência de fossas rudimentares na água subterrânea da região rural de Paulínia/SP

Nas áreas rurais do Brasil 75% da população não tem acesso ao sistema de coleta de esgoto. Nestes locais, o efluente doméstico é despejado em fossas sem impermeabilização, o que permite a infiltração e percolação da porção líquida do efluente no solo e contaminar a água subterrânea. Por esta razão, as fossas negras são uma das principais fontes de contaminação por nitrato de aquíferos rasos. Além desta contaminação, pressupõe-se que as características hidroquímicas de aquíferos rasos em áreas rurais são influenciadas pelo influxo de efluente. Para testar esta premissa, foram coletadas e analisadas amostras de água subterrâneas de nascentes e poços rasos na porção norte do munícipio de Paulínia/SP. Constatou-se que a águas subterrâneas sem ação antrópica à montante possuem reduzida concentração de sólidos totais dissolvidos abaixo de 16 mg/L, sugerindo reduzida influência antrópica. Nascentes situadas à jusante de indústrias apresentaram algum tipo de influência antrópica. As nascentes situadas à jusante de residências rurais e poços rasos próximos destas residências apresentaram características que indicam a influência das fossas sépticas, caracterizadas por concentrações de STD, NO3-, Cl-, SO42- e Na+. Embora representem fontes pontuais, as simulações numéricas de fluxo e transporte demonstram que fossas podem gerar plumas de NO3-, Cl- e Na+ com grandes dimensões. O conjunto de resultados obtidos sugere que a influência do ingresso de efluentes domésticos se manifesta pelos incrementos de STD, NO3-, Cl-, SO42- e Na+. Deste modo, conclui-se que as fossas são importantes agentes atuantes na composição química de aquíferos rasos em áreas rurais.

Monitoramento da qualidade e hidrogeoquímica das águas subterrâneas do setor noroeste da região metropolitana de Fortaleza CE

As ameaças antrópicas para a qualidade da água, como a acidificação e degradação de fontes subterrâneas, têm efeitos cumulativos, aumento dos custos de tratamento para a produção de água potável e podem levar a problemas de saúde humana e perdas econômicas. Com o intuito de aprofundar os conhecimentos sobre as águas subterrâneas em áreas urbanas, no tocante a qualidade e geoquímica, foi realizado um monitoramento em dez (10) poços localizados na Região Metropolitana de Fortaleza que abrangeu diferentes condições climáticas do Estado. As análises químicas foram realizadas no Laboratório de Geoquímica Ambiental da Universidade Federal do Ceará e os procedimentos de controle da qualidade da água para consumo humano foram executados com base na Portaria de Consolidação n° 5, no Anexo XX. Modelagem geoquímica foi realizada com base no cálculo do índice de saturação (IS) das fases minerais hematita, goethita, caulinita e quartzo. No período de monitoramento, todos os resultados analíticos não ultrapassam o valor máximo permitido para consumo humano quanto aos elementos: alumínio, amônia, dureza, sulfato, fluoreto e nitrito. As águas são dominantemente do tipo cloretada-sódica, com nível de STD de águas doces e o de nitrato revela águas não contaminadas na maior porção da área, embora localmente há indícios de contaminação. O modelo geoquímico utilizando Phreeqc demonstrou que as fases apresentam condições de supersaturação em 100% nas composição óxido-hidróxido, indistintamente nos dois sistemas aquíferos. A composição aluminosa apresenta 66,67% dos IS em condições de supersaturação (precipitação) e 33,33% em condições de subsaturação (dissolução). A composição silicosa apresenta 70,96% dos IS em condições de supersaturação (precipitação) e 29,04% em condições de subsaturação (dissolução). O monitoramento possibilitou o estabelecimento de propostas de estratégias de manejo sustentável do sistema aquífero e do uso das águas subterrâneas.