Geochemical fractionation of trace metals and ecological risk assessment of surface sediments in Sepetiba Bay, Brazil.

The Sepetiba Bay (Southeast Brazil) is a known Cd- and Zn-contaminated site that received spills of a large slag pile leachate from a Zn smelter. With important harbors, Sepetiba Bay demands periodic dredging operations which affect the mobility of the metals. The main goal of this work was to assess metal mobility in sediments and its associated toxicity in a fictive dredging area, to evaluate the risks of the operation. To achieve this goal, 18 superficial sediment samples were collected and characterized for pH and Eh. Sediments were analyzed for grain size, organic carbon, and total nitrogen, and metal mobility was evaluated with a sequential extraction procedure, proposed by the European Community Bureau of Reference (BCR). The results demonstrate that Cd and Zn are mainly associated with the exchangeable fraction (mean concentrations 1.4 mg kg-1 and 149.4 mg kg-1, respectively) and reducible fractions (mean concentrations 0.3 mg kg-1 and 65.5 mg kg-1, respectively), while Fe, Cr, Cu, Ni, and Al were associated with the residual fraction. Metals in the residual fraction are probably associated with the mineral lattice of the sediment and should not represent an environmental risk for the biota. The application of the enrichment factor and three risk assessment indexes (Risk Assessment Code, Risky Pollution Index, and Bioavailability Risk Assessment Index) show that the sediments are considerably enriched in metals that constitute a relevant risk for the sediment biota. In the case of dredging operations, Cd and Zn should be released to the overlying waters and be available to organisms, threatening the whole ecosystem. The proposed approach was shown to be much more precise than what is frequently presented in the Environmental Impact Assessments that only consider the threshold limits of the legislation.

Spatial distribution of total mercury and methylmercury in the sediment of a tropical coastal environment subjected to heavy urban inputs.

Jurujuba Cove is located in Guanabara Bay (adjacent to highly populated city of Rio de Janeiro, Brazil), which receives diffuse sources of contaminants along with two main freshwater inputs (the Cachoeira and Icaraí rivers), and hosts mussel farms. The main goal of this work was to evaluate the total mercury (THg) and methylmercury (MeHg) concentrations distributions in the sediments of the cove and their associations with physical and chemical parameters, thereby assessing their geochemical behavior. Twenty samples of surface sediments were collected and characterized for grain size, pH, redox potential, organic carbon, total phosphorus, THg and MeHg. Spatial distribution maps were produced for each parameter and a principal components analysis was carried out, to assess THg and MeHg behavior and their relationships with other parameters. The principal components analysis showed that grain size functions as the main diluting agent. The highest THg concentrations were observed in the mussel-farm area (656.1 ng g-1), and were related to fine grain size and elevated organic carbon values. High MeHg concentrations also occurred in the center of the cove, probably favored by high organic carbon content (low-energy environment). Total phosphorus concentrations indicate that Cachoeira River is a possible source of sewage, but little mercury seems to come from it. The results showed that although total mercury concentrations are elevated, with exception of a few locations, small methylmercury convertion rates were recorded in the sediments.

Innovative microcosm experiments for the evaluation of the regeneration rates of nutrients in sediments of a hypersaline lagoon.

The aim of this study was to evaluate the regeneration of nutrients from the sediments to the water column in varying salinities, with an innovative experiment that closely simulates real environment. In vitro experiments were carried out simulating six scenarios with two sediment types (low carbonate and high carbonate). Local water and sediments were added to microcosms where circulation was forced. Results showed nitrogen release from low carbonate sediment in the lagoon, mixed and seawater (1.69, 4.68 and 7.36 µmol m-2 day-1, respectively). Phosphate diffusive fluxes were positive in lagoon water and low carbonate sediment (2.24 µmol m-2 day-1), negative with mixed water (-0.30 µmol m-2 day-1) and seawater (-0.51 µmol m-2 day-1). A phosphate release surge was observed in the low-carbonate sediment with overlying mixed water and seawater that, in the natural environment, may boost primary production.

Labile metal assessment in water by diffusive gradients in thin films in shipyards on the Brazilian subtropical coast.

Shipyards impact on estuarine environments because of the use of antifouling paints and petroleum products, which release trace metals that may remain in their bioavailable or labile form. Regardless of its importance, the relation between continuous input of trace metals (hotspot area) and their availability in the water column has been scarcely studied. This study evaluated seasonal variations in the concentrations of labile fractions of metals in shipyards located in estuarine areas on the Brazilian subtropical coast. These fractions were determined by the Diffuse Gradients in Thin Films (DGT) technique. Maximum labile fraction concentrations of Cr (0.3 µg L-1), Ni (2.2 µg L-1) and V (2.0 µg L-1) are directly related to (i) their specific source: antifouling paints (for Cr), metal and steel alloys (for Cr and Ni) and petroleum products (for V), besides (ii) periods of intensive traffic and vessel repair. Additionally, variations in labile fractions of Ni and V in the Patos Lagoon estuary were influenced by salinity, which is known to affect metal desorption from surface sediments in resuspension events. Even though Cr is affected by the same processes, it is available as Cr(III) and does not represent any ecological risk in the study areas. Although the areas under study are affected by variations in physical and chemical conditions, shipyards were effectively hotspots of trace metals in their labile fraction in various estuarine systems in southeastern and southern Brazil. Thus, they represent areas where Ecological Risk Assessment, mainly of V, should be carried out.

Development of a Dredging Sensitivity Index, applied to an industrialized coastal environment in Brazil.

Ports link world commerce via maritime routes, and dredging services are essential to establish and maintain these connections. However, one question is critical when dredging is being considered: where are the best places to do it? To try to answer this question, a Dredging Sensitivity Index (DSI) was developed as a management tool to be used in project planning steps. In order to diminish environmental damages and quality-of-life losses, DSI provides alternatives by identifying sensitivity areas. This new methodology quantifies impacts caused by the sediment removal step and points out favorable areas to dredge, with a simple map. Parameters such as fine-grain content (% < 63 µm), Acid Volatile Sulfides (AVS), Shannon-Wiener Index and fisheries, among others, were used to calculate the DSI. Formulas were used to weight and aggregate both, the parameters and the DSI itself. Sepetiba Bay was chosen to apply this methodology because of its relevant economic and environmental aspects. The methodology was applied to dredging situations, but it can be used to indicate areas for dredged material disposal, with a few modifications in the DSI formulas. A DSI map was a final result of this methodology, and showed that the northern portion of the bay, close to the littoral is a more sensitive area, where dredging should be avoided, or carried out very carefully. DSI is a very useful tool for reducing damages from dredging services, it contributes with zonation and it provides alternatives to decision-makers who manage these areas.

Separation of Escherichia coli from natural samples for identification of sources and microcosm inoculation.

Obtaining uncultured Escherichia coli from natural waters is an important step in the study of microbes in the environment, which are critical for bacterial decay and microbial source tracking. The quality of the samples used can influence the assays, because high contaminant concentrations, differing cell ages, and physiologic states can impair results. The proposed separation is based on a three-step filtration method applied to replicates of seven samples from a sewage plant affluent, collected in different periods. Aliquots of the leachate were inoculated into microcosms, aiming to observe the cultivability of the cells. The assay resulted in colimetry values ranging between 104 and 105 cells. In the leachate, averages of 1.05% of total coliforms and 1.10% of Escherichia coli were recovered from original samples. Although enduring unfavorable temperatures, salinities, and nutritional conditions, the inoculated microcosm populations grew approximately 310 times after 24 h. The final leachate contained cultivable cells in appropriate physiological states and quantities for inoculum in microcosm sets. The bacteria obtained from the leachate were also appropriate for surveys of microbial source tracking, because, in the developed procedure, organisms were separated from contaminants, while cell concentrations were sufficient for inocula.

Potential availability of trace metals in sediments in southeastern and southern Brazilian shipyard areas using the DGT technique and chemical extraction methods.

Speciation and partitioning of trace metals, from solid to solution phases of sediments, control their bioavailability and thus their potential ecological risk to organisms. Therefore, in order to obtain a broad evaluation of their risk, it is necessary to couple methodologies that are able to assess metal mobility in sediment. In this study, the Diffusive Gradients in Thin Films (DGT) technique and the application of 0.1 M HCl acid extraction methods, together with solid-state voltammetric sensors, were used with the objective of assessing mobility and potential availability of Cr, Cu, Ni, Pb, V and Zn in sediment porewaters and solid sediments in southeastern and southern Brazilian shipyard areas. The highest labile metal concentrations were found in shipyards with the longest histories of operations. Trace metal distributions in porewater and in the solid phase of sediments (labile metals) and significant correlations among metals enabled to distinguish the contribution of anti-fouling paint components. The diffusive flux of every metal measured at the surface of the sediment indicated that CuDGT had the highest flux (3.66E-03 mmol·m-2 d-1) in the shipyard with the longest operating time. Therefore, enrichment was observed for Cu, Pb and Zn in sediments, indicating a possible ecological risk level of 'Effects Range Median' to 'Apparent Effects Threshold' for oyster larvae (Mollusca) (Cu), bivalves (Pb) and the infaunal community (Zn). Probable Effect Concentrations (PEC) to sediment-dwelling biota can be expected as well, related to high concentrations of Cu and Zn in sediment. This study allowed a comprehensive evaluation of potential bioavailability and ecological risk of trace metals in aquatic systems where there is continuous and specific input of these elements. The use of the DGT technique with solid-state voltammetry in the sediment of distinct Brazilian estuarine systems demonstrated its potential to be applied in future environmental network programs.

Spatial distribution of water quality in the Amazonian region: implications for drinking water treatment procedures.

Riparian communities in the Amazon suffer from water-borne diseases due to the lack of adequate water treatment capabilities. Therefore, small local water treatment plants are necessary, but the selection of treatment procedures depends largely on the physico-chemical characteristics of the water. The aim of the present research was to evaluate the physico-chemical characteristics of the water in the Amazon River and its tributaries, in order to determine customized processes for water treatment. Data from 54 fluviometric monitoring stations were organized and used to construct distribution maps. The parameters such as pH, electrical conductivity, and the concentration of suspended matter, turbidity and flow rates were evaluated. Results showed that pH was very acidic (4-5) in the northwestern portion of the region while conductivity was quite low in the entire Amazonian region (<140 µS cm-1). Both parameters were strongly influenced by geological settings and sources of organic matter. Suspended matter and turbidity were affected by weathering processes. It was concluded that considering the acidity of the waters, mechanical procedures like filtration or slow settling should be applied to remove suspended matter rather than chemical procedures. For disinfection, instead of chemicals, solar energy should be applied.

Evaluation of contaminants spreading from sludge piles, applying geochemical fractionation and attenuation of concentrations model in a tropical reservoir.

Drinking water production may generate significant amounts of sludge, which may be contaminated with various metals. For the first time, the mobility/lability of contaminants from two water treatment sludge piles in the Juturnaíba Reservoir was evaluated by applying two geochemical approaches: sequential extractions and attenuation of concentrations model. Both procedures were applied to evaluate the mobility/lability of Al, Cr, Cu, Fe, Mn, and Zn on samples collected in the sludge piles and in the neighborhood of both water treatment plants. The results show that aluminum presents considerably higher concentrations in the sediments close to the sludge piles, with more labile phases; however, the attenuation of concentrations model indicates little spreading of this contaminant in the reservoir. Manganese was shown to be severely depleted in the sludge, indicating that it can be leached away, due to the reducing conditions of the pile. The other elements showed low concentrations and were shown not to affect the concentrations in the reservoir. While the geochemical fractionation indicates the possibility of dissolution to the water column, the attenuation of concentrations model gives information on the spatial dispersion of the contaminants, constituting interesting complementary approaches.

Mercury contamination in the sludge of drinking water treatment plants dumping into a reservoir in Rio de Janeiro, Brazil.

Although sludge piles from drinking water treatment plants can contain harmful substances, in many countries, their disposal methods are still unregulated. Besides aluminum, which is a major constituent in these residues, many other contaminants-like trace metals-can be present and may result from the quality of the raw materials used for water treatment. The application of these chemicals for the treatment of drinking water can generate toxic sludge and contaminate the produced water. In the present work, mercury contamination in the sludge piles of two drinking water treatment plants located along the margins of the Juturnaíba Reservoir, Southeast Brazil, was evaluated to verify whether contaminants are incorporated during water treatment. In the summer 2012, five cores were collected from the piles, and were analyzed for Eh, granulometry, total carbon, total nitrogen, and total mercury. The results indicated an anoxic environment, reflecting composition of the suspended matter. Carbon and nitrogen presented elevated concentrations, but also seemed to reproduce the characteristics of the suspended matter in the raw water. The concentrations of mercury were extremely variable but presented unexpectedly high values in some of the layers, reaching 18,484 ng g-1. On the other hand, concentrations ten times lower than those observed in the natural system (8 ng g-1) could be observed. It was concluded that the only possible source for the contamination of the sludge was the chemicals used for water treatment.

Volumetric modeling of two sludge piles from water treatment plants in a Brazilian reservoir.

Water treatment plants are designed to continuously produce drinkable water, meeting defined criteria of potability. However, besides potable water, these plants produce sludges that are disposed of in the environment. The present work aimed to evaluate the sludges generated in two water treatment plants and disposed of in the margin of the Juturnaíba dam. Since alum has been used as a flocculating agent in these two plants, the concentrations of aluminum were measured in the sludges and in surface sediments. The generated piles are extremely soft to walk on and difficult to measure, so indirect modeling procedures had to be applied. The calculated mass of the sludge piles at each plant are similar and respectively 60,370 and 61,479 tons. The aluminum content of the residues, calculated according to its dosage, was 33.2 and 32.6 g kg-1 in the piles from the two plants. The amount of alum dosed to the water corresponds almost to the excess of aluminum in the sludge, compared to the sediments. It was concluded that regardless of the fact that residues are disposed of in very restricted areas, they are directly in contact with the water and may constitute a threat for the environment and humans' health.

Cross-cultural adaptation of an environmental health measurement instrument: Brazilian version of the health-care waste management • rapid assessment tool.

BACKGROUND: Periodic assessment is one of the recommendations for improving health-care waste management worldwide. This study aimed at translating and adapting the Health-Care Waste Management - Rapid Assessment Tool (HCWM-RAT), proposed by the World Health Organization, to a Brazilian Portuguese version, and resolving its cultural and legal issues. The work focused on the evaluation of the concepts, items and semantic equivalence between the original tool and the Brazilian Portuguese version. METHODS: A cross-cultural adaptation methodology was used, including: initial translation to Brazilian Portuguese; back translation to English; syntheses of these translation versions; formation of an expert committee to achieve consensus about the preliminary version; and evaluation of the target audience's comprehension. RESULTS: Both the translated and the original versions' concepts, items and semantic equivalence are presented. The constructs in the original instrument were considered relevant and applicable to the Brazilian context. The Brazilian version of the tool has the potential to generate indicators, develop official database, feedback and subsidize political decisions at many geographical and organizational levels strengthening the Monitoring and evaluation (M&E) mechanism. Moreover, the cross-cultural translation expands the usefulness of the instrument to Portuguese-speaking countries in developing regions. CONCLUSION: The translated and original versions presented concept, item and semantic equivalence and can be applied to Brazil.

Predicting pollutant concentrations in the water column during dredging operations: Implications for sediment quality criteria.

The development of new dredging techniques that can reduce, or at least predict, the environmental impacts, is in high demand by governments in developing countries. In the present work, a new methodology was developed, to evaluate the level of metals contamination (i.e. cadmium, lead and zinc) of the water column, during a dredging operation. This methodology was used to evaluate the impacts of the construction of a new maritime terminal in Sepetiba Bay, Brazil. The methodology quantifies the amount of resuspended sediments and calculates the expected contaminants concentrations in the water column. The results indicated that sediment quality criteria were not compatible with water quality criteria, because the dredging of contaminated sediments does not necessarily yield contaminated water. It is suggested that the use of sediment quality criteria for dredging operations might be abandoned, and the methodology presented in this study applied to assess dredging's environmental impacts, predicting water contamination levels.

Planning dredging services in contaminated sediments for balanced environmental and investment costs.

Dredging of contaminated sediments has shown to be a harmful activity for the environment, because a number of contaminants can be resuspended and become available to the organisms. Furthermore, dredged contaminated sediments may cause significant damages in the dumping site. In order to avoid the drawbacks of this activity, better techniques have to be developed and the present article presents a new procedure for the planning of dredging that reduces the environmental impacts by reducing the amount of dredged sediments and, at the same time, reduces costs. The new technique uses screening of contaminant concentrations in the sediments that are normally part of the environmental impact assessment for dredging activity. A detailed mapping of the contamination, layer by layer is carried out and the areas where the action levels are reached are outlined with polygons, establishing limits within which sediments have to be dredged with safe procedures. In the case presented, construction of a harbor in Sepetiba Bay, Rio de Janeiro, Brazil, the safe procedure is cutter/suction dredging and pumping into a sub-aquatic confined disposal facility (CDF). A detailed evaluation of costs showed that if the whole layers of sediment were to be dumped into the CDF, the cost of the activity would be at least 63.82% more expensive than the proposed procedure, constituting an attractive advantage. Furthermore, as the size of the CDF is significantly smaller, less dredging is necessary, causing smaller environmental impact.

Combined SEM/AVS and attenuation of concentration models for the assessment of bioavailability and mobility of metals in sediments of Sepetiba Bay (SE Brazil).

This study proposes a new methodology to study contamination, bioavailability and mobility of metals (Cd, Cu, Ni, Pb, and Zn) using chemical and geostatistics approaches in marine sediments of Sepetiba Bay (SE Brazil). The chemical model of SEM (simultaneously extracted metals)/AVS (acid volatile sulfides) ratio uses a technique of cold acid extraction of metals to evaluate their bioavailability, and the geostatistical model of attenuation of concentrations estimates the mobility of metals. By coupling the two it was observed that Sepetiba Port, the urban area of Sepetiba and the riverine discharges may constitute potential sources of metals to Sepetiba Bay. The metals are concentrated in the NE area of the bay, where they tend to have their lowest mobility, as shown by the attenuation model, and are not bioavailable, as they tend to associate with sulfide and organic matter originated in the mangrove forests of nearby Guaratiba area.

An overview of mercury contamination research in the Amazon basin with an emphasis on Brazil.

This article provides an overview of research on mercury contamination in the Amazon Basin and its evolution from 1990 to 2005. The assessment was based on an extensive and systematic review using bibliographic databases available online and a review of projects by research groups. Brazilian research groups were identified using the database of the Brazilian National Research Council (CNPq). A geographic information system was used to determine the location of the studies. Different aspects of mercury contamination were evaluated (environmental studies, impacts on human health, technological improvements). For 1990-2005, a total of 455 publications were identified. The main advances and remaining gaps in relation to environmental issues and human health were identified and discussed. Although the scientific output varied considerably over the period, there was a general increase in the total number of publications per year from the early 1990s (fewer than 20) until 2005 (more than 30), considering the articles published in indexed journals.

An overview of mercury contamination research in the Amazon basin with an emphasis on Brazil / Uma revisão das pesquisas sobre contaminação por mercúrio na Amazônia com ênfase no território brasileiro

This article provides an overview of research on mercury contamination in the Amazon Basin and its evolution from 1990 to 2005. The assessment was based on an extensive and systematic review using bibliographic databases available online and a review of projects by research groups. Brazilian research groups were identified using the database of the Brazilian National Research Council (CNPq). A geographic information system was used to determine the location of the studies. Different aspects of mercury contamination were evaluated (environmental studies, impacts on human health, technological improvements). For 1990-2005, a total of 455 publications were identified. The main advances and remaining gaps in relation to environmental issues and human health were identified and discussed. Although the scientific output varied considerably over the period, there was a general increase in the total number of publications per year from the early 1990s (fewer than 20) until 2005 (more than 30), considering the articles published in indexed journals.

Esta pesquisa apresenta uma visão geral dos estudos desenvolvidos sobre a contaminação por mercúrio na bacia Amazônica e a evolução destes estudos no período 1990-2005. O estudo baseou-se em extensiva e sistemática revisão utilizando bases de dados bibliográficas disponíveis na Internet e em uma revisão dos projetos de pesquisa realizados por grupos de pesquisa. Além disso, os grupos de pesquisa brasileiros foram identificados pela base de dados do Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq). Um sistema de informação geográfica foi usado para localizar os estudos conduzidos. Diferentes aspectos da contaminação por mercúrio na Amazônia foram analisados (estudos ambientais, impactos na saúde humana, melhorias tecnológicas). No período de 1990-2005, foram identificadas 455 publicações. As principais realizações e as lacunas existentes em relação aos estudos ambientais e de saúde humana foram identificadas e discutidas. Apesar de variações, há um aumento geral do número total de publicações por ano desde o começo da década de 1990 (menos de 20) para o final do período estudado (mais de 30), expresso por meio dos artigos publicados em revistas indexadas.

Characterization of hydrocarbonoclastic bacterial communities from mangrove sediments in Guanabara Bay, Brazil.

Hydrocarbonoclastic bacterial communities inhabiting mangrove sediments were characterized by combining molecular and culture-dependent approaches. Surface sediments were collected at two sampling sites in Guanabara Bay (Rio de Janeiro, Brazil) and used to inoculate in vitro enrichment cultures containing crude oil to obtain hydrocarbonoclastic bacterial consortia. In parallel, in situ mesocosms (located in the Guapimirim mangrove) were contaminated with petroleum. Comparison of bacterial community structures of the different incubations by T-RFLP analyses showed lower diversity for the enrichment cultures than for mesocosms. To further characterize the bacterial communities, bacterial strains were isolated in media containing hydrocarbon compounds. Analysis of 16S rRNA encoding sequences showed that the isolates were distributed within 12 distinct genera. Some of them were related to bacterial groups already known for their capacity to degrade hydrocarbons (such as Pseudomonas, Marinobacter, Alcanivorax, Microbulbifer, Sphingomonas, Micrococcus, Cellulomonas, Dietzia, and Gordonia groups). Other strains, with high capacity for degrading hydrocarbons (aliphatic or aromatic), were related to isolates from hydrothermal vents that have not been thus far detected in hydrocarbon-contaminated sites, nor described for their ability to grow or degrade petroleum hydrocarbons. Degradation studies showed the ability of Marinobacter, Alcanivorax and Sphingomonas isolates to degrade both PAH and alkane compounds. Our results point out the rich microbial diversity of the mangroves, whose potential for hydrocarbon degradation is promising for future studies on pollutant bioremediation.

Biogeochemistry of mercury in the Amazonian environment.

In this paper, the processes that affect mercury (Hg) cycling in the Amazonian environment were reviewed, criticized and new directions of research are proposed. The discussion of the origin of the mercury contamination, whether natural or anthropogenic is marked by a lack of fundamented arguments from both sides. Undoubtedly mercury inputs from gold mining have locally increased environmental concentrations, but in the whole Amazon, these loads would be insignificant, considering the high concentrations observed by some authors in remote soils. A reasonable process that should explain these elevated concentrations in soil is that B horizons function as a mercury "sponge" that have been accumulating mercury over a geological time scale, releasing it back to cycling during erosion and forest fires. The environmental degradation of the Amazonian forest due to human activities is probably enhancing the release of that mercury to the cycle. Mercury transformations in reduced, anoxic environments--sediments and waters--are also a key problem for the understanding of the environmental methylation. The studies that have been carried out in the Amazonian environment are too restricted and results permit only circumstantial conclusions. Large efforts must be directed to monitoring programs considering time and space variability.

The fate of anionic surfactants in a tropical choked lagoon in Se Brazil

Anionic surfactants have been surveyed in a choked lagoon (Piratininga, Niteroi, RJ, Brazil) in order to provide knowledge on the dynamics and distribution of this pollutant. Samples were collected from 7 stations in the drainage basin and in the laggon itself. Temperature, salinity, pH, BOD, dissolved oxygen, dissolved forms of nitrogen and phosphorus and anionic surfactants were measured in the water column. The physicochemical results show that the water quality in the river stations is low, due to the domestic sewage directly dumped into the system. The anionic surfactant concentrations show that the sources for this pollutant are not restricted to the drainage basin, but widespread in the margins of the lagoon. Furthermore, the concentrations seem to show that the biodegradation rate is low and dilution is more important in reducing contamination.