Adapted Sequential Extraction Protocol to Study Mercury Speciation in Gold Mining Tailings: Implications for Environmental Contamination in the Amazon.

Artisanal small-scale gold mining (ASGM), an increasingly prevalent activity in South America, generates mercury-contaminated tailings that are often disposed of in the environment, leading to the introduction of mercury into ecosystems and the food web, where it bioaccumulates. Therefore, studying the geochemical processes involved in the desorption and dissolution of mercury in these tailings is essential for critical risk evaluations in the short and long term. For this purpose, sequential extraction procedures (SEPs) can be useful because they help to identify the phases to which Hg is associated, although they also have limitations such as a lack of selectivity and specificity. In this work, we propose a modified four-step SEP: exchangeable mercury (F1), oxidizable mercury (F2), mercury bound to Fe oxides (F3), and strongly bound mercury (F4). To test this adapted sequential extraction method, we evaluated the Hg contamination in mercury-contaminated tailings of the Amazon basin. The results revealed a total mercury concentration of 103 ± 16 mg·kg-1 in the tailings, with a significant portion in F1 (28% of the total), where Hg was bioavailable. The large Hg concentration in F3 (36%) suggested that Fe oxides likely contribute to mercury retention. Together, the SEP results emphasize the urgent need for improved surveillance of gold mining activities and responsible tailings management practices to mitigate environmental contamination and safeguard the health of the Amazon ecosystem.

Exploring a new approach for assessing the fate and behavior of the tailings released by the Brumadinho dam collapse (Minas Gerais, Brazil).

In 2019, the Brumadinho dam rupture released a massive amount of iron ore mining tailings into the Paraopeba River. Up to now, it remains a public health issue for the local and downstream populations. The present study aims to assess the behavior and fate of metal contamination following the disaster. Using new sampling strategies and up-to-date geochemistry tools, we show that the dissolved metal concentrations (< 0.22 µm cutoff filtration) remained low in the Paraopeba River. Although the tailings present high metal concentrations (Fe, Mn, Cd, and As), the high local background contents of metals and other previous anthropogenic contamination hamper tracing the sediment source based only on the geochemical signature. The Pb isotopic composition coupled with the metals enrichment factor of sediments and Suspended Particulate Matter (SPM) constitutes accurate proxies that trace the fate and dispersion of tailing particles downstream of the dam collapse. This approach shows that 1) The influence of the released tailing was restricted to the Paraopeba River and the Retiro Baixo reservoir, located upstream of the São Francisco River; 2) The tailings' contribution to particulate load ranged from 17 % to 88 % in the Paraopeba River; 3) Other regional anthropogenic activities also contribute to water and sediment contamination of the Paraopeba river.

Continuous Monitoring of Suspended Particulate Matter in Tropical Inland Waters by High-Frequency, Above-Water Radiometry.

Water and sediment discharges can change rapidly, and low-frequency measurement devices might not be sufficient to elucidate existing dynamics. As such, above-water radiometry might enhance monitoring of suspended particulate matter (SPM) dynamics in inland waters. However, it has been barely applied for continuous monitoring, especially under partially cloudy sky conditions. In this study, an in situ, high-frequency (30 s timestep), above-water radiometric dataset, collected over 18 days in a tropical reservoir, is analyzed for the purpose of continuous monitoring of SPM concentration. Different modalities to retrieve reflectance spectra, as well as SPM inversion algorithms, were applied and evaluated. We propose a sequence of processing that achieved an average unsigned percent difference (UPD) of 10.4% during cloudy conditions and 4.6% during clear-sky conditions for Rrs (665 nm), compared to the respective UPD values of 88.23% and 13.17% when using a simple calculation approach. SPM retrieval methods were also evaluated and, depending on the methods used, we show that the coefficient of variation (CV) of the SPM concentration varied from 69.5% down to 2.7% when using a semi-analytical approach. As such, the proposed processing approach is effective at reducing unwanted variability in the resulting SPM concentration assessed from above-water radiometry, and our work paves the way towards the use of this noninvasive technique for high-frequency monitoring of SPM concentrations in streams and lakes.

Spatiotemporal analysis of traffic emissions in over 5000 municipal districts in Brazil.

Exposure to traffic emission is harmful to human health. Emission inventories are essential to public health policies aiming at protecting human health, especially in areas with incomplete or nonexistent air pollution monitoring networks. In Brazil, for example, only 1.7% of municipal districts have a monitoring network, and only a few studies have reported data on vehicle emission inventories. No studies have presented emission inventories by municipality. In this study, we predicted vehicular emissions for 5570 municipal districts in Brazil during the period 2001-2012. We used a top-down method to estimate emissions. Carbon dioxide (CO2) is the pollutant with the highest emissions, with approximately 190 million tons per year during the period 2001-2012). For the other traffic-related pollutants, we predicted annual emissions of 1.5 million tons for carbon monoxide (CO), 1.2 million tons of nitrogen oxides (NOx), 209,000 tons of nonmethane hydrocarbons (NMHC), 58,000 tons of particulate matter (PM), and 42,000 tons for methane (CH4). From 2001 to 2012, CO, NMHC, and PM emissions decreased by 41, 33, and 47%, respectively, whereas those CH4, NOx, and CO2 increased by 2, 4, and 84%, respectively. We estimated uncertainties in our study and found that NOx was the pollutant with the lowest percentage difference, 8%, and NMHC with the highest one, 30%. For CO, CH4, CO2, and PM, the values were 22, 14, 21, and 20%, respectively. Finally, we found that during 2001 and 2012 emissions increased in the Northwest and Northeast. In contrast, pollutant emissions, except for CO2, decreased in the Southeast, South, and part of Midwest. Our predictions can be critical to efforts developing cost-effective public policies tailored to individual municipal districts in Brazil. IMPLICATIONS: Emission inventories may be an alternative approach to provide data for air quality forecasting in areas where air quality data are not available. This approach can be an effective tool in developing spatially resolved emission inventories.

A novel land use approach for assessment of human health: The relationship between urban structure types and cardiorespiratory disease risk.

Extensive evidence shows that in addition to lifestyle factors, environmental aspects are an important risk factor for human health. Numerous approaches have been used to estimate the relationship between environment and health. For example, the urban characteristics, especially the types of land use, are considered a potential proxy indicator to evaluate risk of disease. Although several studies have used land use variables to assess human health, none of them has used the concept of Urban Morphology by Urban Structure Types (USTs) as indicators of land use. The aim of this study was to assess the relationship between USTs and cardiorespiratory disease risks in the Federal District, Brazil. Toward this end, we used a quantile regression model to estimate risk. We used 21 types of UST. Income and population density were used as covariates in our sensitivity analysis. Our analysis showed an association between cardiorespiratory diseases risk and 10 UST variables (1 related to rural area, 6 related to residential area, 1 recreational area, 1 public area and 1 commercial area). Our findings suggest that the conventional land use method may be missing important information about the effect of land use on human health. The use of USTs can be an approach to complement the conventional method. This should be of interest to policy makers in order to enhance public health policies and to create future strategies in terms of urban planning, land use and environmental health.

A spatial multicriteria model for determining air pollution at sample locations.

Atmospheric pollution in urban centers has been one of the main causes of human illness related to the respiratory and circulatory system. Efficient monitoring of air quality is a source of information for environmental management and public health. This study investigates the spatial patterns of atmospheric pollution using a spatial multicriteria model that helps target locations for air pollution monitoring sites. The main objective was to identify high-priority areas for measuring human exposures to air pollutants as they relate to emission sources. The method proved to be viable and flexible in its application to various areas.

Biomonitoramento passivo com casca de aroeira vermelha (Myracrodruon urundeuva Lorenzi Harri) para verificar a variabilidade espacial da poluição atmosférica em uma região do Distrito Federal, Brasil / Passive biomonitoring with hull aroeira vermelha (Myracrodruon urundeuva Lorenzi Harri) to verify spatial variability of air pollution in a region of the Federal District, Brazil

O biomonitoramento é uma técnica alternativa que utiliza organismos vivos para verificar mudanças no meio ambiente ocasionadas pela poluição da água, ar e solo. Tendo como foco as emissões atmosféricas localizadas na região da Fercal no Distrito Federal, o presente estudo objetivou coletar amostras de casca da árvore da espécie Myracrodruon urundeuva para verificar a variabilidade espacial dos elementos químicos presentes na área de estudo. A análise de componente principal (PCA) permitiu agrupar os elementos em três fatores, distribuídos no fator 1: Zn, Fe, Al, S e Ba; no fator 2: Cu, P, Ca e Sr; e no fator 3: Mg e K. O fator 1 é o que melhor descreve o objeto de pesquisa. Este estudo permitiu demonstrar a viabilidade do método de biomonitoramento com casca de aroeira vermelha (Myracrodruon urundeuva) como instrumento de mensuração da poluição atmosférica.

Biomonitoring is an alternative technique that uses living organisms to verify changes in the environment caused by pollution of water, air and soil. Focusing on atmospheric emissions at Fercal, located in the Federal District region, the present study aimed to collect samples of the bark of the species Myracrodruon urundeuva to verify the spatial variability of the chemical elements present in the study area. The principal component analysis (PCA) allowed to group the elements into three factors: factor 1: Zn, Fe, Al, S, and Ba; factor 2: Cu, P, Ca, and Sr; and factor 3: Mg and K. Factor 1 is the one that best describes the research object. This study has demonstrated the feasibility of the method of biomonitoring with the bark of aroeira vermelha (Myracrodruon urundeuva) as an instrument for measuring air pollution.