The Amazon suffers from the occurrence of mining along its hydrographic routes, which releases toxic substances into the aquatic environment. The objective of this study was to evaluate the risk of contamination by As and Hg that indigenous peoples are exposed to through the consumption of fish in an area impacted by mining activity in the basin of the Curuá and Baú Rivers, Altamira-PA. In total, 55 fish specimens and 30 surface water samples were collected. The decomposition of the fish samples was done by wet method with the use of nitric acid, hydrogen peroxide, and microwaves. The quantification of total mercury (THg) and total arsenic (TAs) was carried out by inductively coupled plasma optical emission spectrometry with vapor generation (VG-ICP OES). The methodology proposed by the U.S. Environmental Protection Agency was used. The results showed that TAs presents safe levels; however, THg presents a sample with levels up to (4.6 µg g 1), exceeding the permitted levels (1 µg g 1). The risk assessment shows that only the consumption of fish, linked to Hg, represents the existence of deleterious risks to indigenous peoples (hazard quotient (HQ)) > 1). Bioaccumulation factor (BAF) in fish represents a risk to indigenous people, because of the Hg’s presence. The study identified that illegal mining activities are responsible for Hg pollution in the Baú and Curuá Rivers. The fish species analyzed can be used as bioindicators of Hg in the rivers, which is relevant for making environmental and public health policy decisions.

The introduction of potentially toxic elements (PTEs) from industrial activities in water bodies, highlights the vulnerability of the environment and the need for actions focused on the implementation of mechanisms that help in the control and remediation of these impacts. The objective of the study was based on the integration of instrumental analytical methods, multivariate statistics, and computer simulation models, with the proposal of implementing realistic scenarios of the red mud plume behavior in the Pará River. The selected location was the municipality of Barcarena-PA, where is located an important alumina/aluminum industrial center. With the aid of the inductively coupled plasma optical emission spectrometer (ICP OES), the chemical elements Al, B, Cr, Fe, Mn, P, Ti, and Zn were quantified and the principal component analysis (PCA) allowed to select Al, B, Fe, P, and Zn as the most relevant with 98.68% of the accumulated variance. Some scenarios were proposed by the simulated hydrodynamic model, which evidenced that the Trambioca community would be the most affected in the first 13 h after the effluent overflowed, and the other locations in domino effect. The main scientific gain of the proposal is the possibility of the predictive scenarios to help the actions of containment and mitigation of environmental damages by public control agencies, institutions involved, and other competent bodies.

This study provides a risk assessment and risk maps related to the consumption of water contaminated by Al, Ba, Fe and Pb in an industrial area in the Brazilian Amazon. A total of 120 samples of drinking water were collected from 26 locations in the municipality of Barcarena, Pará State. Multiple elements were analyzed by inductively coupled plasma optical emission spectrometry. The quantifiable elements in the samples were Al, Ba, Fe and Pb. Risk assessment was performed according to U.S. Environmental Protection Agency (USEPA) procedures. Results indicate that the highest potential risk of non-carcinogenic adverse health effects for Al was in São João Island; for Ba, Fe and Pb (hazard quotient (HQ) > 1) were in Porto da Balsa community, in the city of Barcarena and Distrito Industrial community, respectively. Maps showed that areas located near Barcarena’s industrial complex are the most affected by water contamination. Therefore, these populations are at higher risk of non-carcinogenic problems, especially children and the elderly, since the majority of the population resides in these areas. Geospatial analysis contributed to delimiting and analyzing risk-change trends in the region, expanding the scope of results to a decision-making process.

A novel carbon composite was prepared from a mixture of coffee waste and clay with inorganic:organic ratio of 1.3 (CC-1.3). The mixture was pyrolysed at 700 °C. Considering the application of this adsorbent for removal of anionic dyes, the CC-1.3 was treated with a 6 mol L-1 HCl for 24 h to obtain ACC-1.3. Fourier transform infrared (FTIR), N2 adsorption/desorption curves, scanning electron microscope (SEM) and powder X-ray diffractometry (XRD) were used for characterisation of CC-1.3 and ACC-1.3 carbon adsorbents. The adsorbents were effectively utilised for removal of reactive blue 19 (RB-19) and reactive violet 5 (RV-5) textile dyes from aqueous solutions. The maximum amounts of RB-19 dye adsorbed at 25 °C are 63.59 (CC-1.3) and 110.6 mg g-1 (ACC-1.3), and 54.34 (CC-1.3) and 94.32 mg g-1 (ACC-1.3) for RV-5 dye. Four simulated dye-house effluents were used to test the application of the adsorbents for treatment of effluents.

Amostras de cabelo foram utilizadas como bioindicador para avaliar os níveis de As, Cd, Pb e Hg na população residente na área "Volta Grande" do rio Xingu, no Norte do Brasil. As concentrações de As e Cd estão de acordo com os valores encontrados na literatura, no entanto, foram encontrados valores anômalos de Pb e Hg , o que pode sugerir uma variação inter-regional. Os elevados valores encontrados de Pb e Hg, em cabelos de moradores da Ilha do Canteiro, podem ser atribuídos à exposição ambiental das famílias, por estarem em uma área ambiental impactada pela mineração de ouro. A aplicação dos métodos de estatística multivariada mostrou que a concentração dos metais, estudados neste trabalho, pode ser classificatória entre pessoas de localidades diferentes do município de Altamira. Os resultados neste trabalho refletem o impacto ambiental destes elementos sobre a saúde dos habitantes desta área de garimpagem de ouro.

Human hair was used as a bioindicator to evaluate the levels of As, Cd, Pb and Hg in the resident population of the "Volta Grande" area of the Xingu river, in the North of Brazil. The concentrations of As and Cd are in agreement with the values found in the literature, however, the Pb and Hg concentration is very different, which can suggest an inter-regional variation. Moreover, the high values found for these elements in the residents of the Canteiro Island can be attributed to environmental exposure of this population in an area with environmental impact from activities of gold mining. The application of these methods showed that the concentrations of the metals studied in this work can correctly classify two different localities in the Altamira district. The results reflect the impact of these elements on the health of the inhabitants of this auriferous area.