The Paraíba do Sul River Basin and its coastal area as a study model of the mercury cycle: A meta-analytical review of three decades of research

The Paraíba do Sul River (PSR) Basin is a crucial drainage basin in Southeast Brazil, being the most industrialized and densely populated region in the country. Over the last three decades, the basin has been the subject of numerous studies due to its long history of mercury (Hg) contamination. This makes the PSR Basin an excellent model to evaluate Hg cycling, which is a priority for signatory countries of the Minamata Convention, which includes Brazil. This review compiled data on Hg from five environmental compartments (animals, plants, sediment, suspended particulate matter (SPM), and water), three different sectors (upper, middle, and lower) and five different ecosystems (reservoir, mangrove, fluvial, estuarine, and coastal) from 60 published studies, aiming to understand the Hg cycling through meta-analyses. The highest concentrations of Hg were observed in the upper and middle sectors of the basin, which are areas with high industrialization and urbanization levels. Among the evaluated ecosystems, hydropower reservoirs showed the highest medians and were also frequent in the upper and middle portions of the PSR basin. Over the years, all environmental compartments showed a decline in Hg concentrations due to the implementation of federal and state environmental policies. The main source of Hg for the basin was Hg-rich soils from past activities (such as artisanal small-scale gold mining and the use of organomercurial fungicides in sugarcane plantations). These results can assist decision-makers in the management of the basin's ecosystems and can also be used to evaluate the effectiveness of implementing the Minamata Convention in the region.

Effects of dams on As and Hg concentrations in three southeastern Brazil fluvial systems: Ocean inputs, sources and seasonal dynamics among environmental compartments

Damming rivers for hydropower generation interferes in the flow of water bodies and, consequently, in trace element biogeochemistry and transport. This study focused on the effects of dams on the seasonal dynamics of arsenic (As) and mercury (Hg) in three fluvial systems (Itabapoana River, Flechas Channel and Paraíba do Sul River) and on the input of these elements to the ocean. The elements were evaluated in suspended particulate matter (SPM), surface sediments, and the roots of the aquatic macrophyte Eichhornia crassipes. Our results showed that the proximity of the dams in the Flechas Channel and Rio Itabapoana in relation to their mouth (distances of 4 km and 58 km, respectively) changed As and Hg seasonal dynamics in the environmental compartments analyzed, with the Flechas Channel being the most impacted area. In contrast, the lower part of the Paraíba do Sul River that has more distant dams to its mouth (distance of 184 km) did not show such marked changes, suggesting that most of the inputs are coming from the long river reach. The isotopic and elemental composition of organic matter indicated the soils of native forests as the main source of trace elements to the water bodies. Flow rate was the main driver controlling As and Hg ocean inputs, with higher inputs observed in the Paraíba do Sul River (9.69 and 0.59 t∙year^-1, respectively) compared to the other assessed fluvial systems. Also, this study demonstrated that, if a dam is closer to the mouth of a river, less contaminants will be input.

ECG abnormalities and their relation to COVID-19 outcomes – a WHF study

Introduction

COVID-19 is a respiratory tract infection caused by the Coronavirus (SARS-CoV-2) and its main clinical manifestations are respiratory. The cardiovascular system can also be affected, especially in patients with severe acute respiratory syndrome [1].

On the other hand, cardiovascular disease (CVD) and risk factors have been shown to be predictors of poor outcomes in COVID-19 [2]. Diverse electrocardiographic abnormalities can be found in this condition [3], although their value as a prognostic predictor have not been properly established due to heterogeneity in abnormalities evaluation and small sample sizes in related studies [4].

Purpose

The aim of the present study is to evaluate the association of electrocardiogram (ECG) findings to poor COVID-19 outcomes

Methods

This is a multicentric cohort study that followed hospitalized adults due to COVID-19, from low-middle and high-income countries as part of the World Heart Federation (WHF) Global Study on CVD and COVID-19 initiative [5]. Participants were followed up from hospital admission until 30 days post discharge. For the present study, participants with a valid ECG were included. ECG findings were described according to standardized measurements [heart rate, PR interval, QRS duration and axis, corrected QT interval (QTc)] and abnormalities (according to the Minnesota code system). Abnormalities utilized were grouped into ischemic abnormalities (q waves and ST-T abnormalities), atrial fibrillation (AF), prolonged QTc, sinus tachycardia (defined for the study as above 120 bpm), right and left bundle branch block and presence of any major abnormality. The primary outcome was defined as death from any cause. The secondary outcomes were intensive care unit (ICU) admission and cardiovascular events (myocarditis, pericarditis, myocardial infarction, acute heart failure, ischemic and hemorrhagic stroke). Multiple logistic regression was used to evaluate the association of ECG abnormalities to the outcomes of interest. Adjustments were made in a step by step fashion including gender, age, country of residence, cardiovascular risk factors (diabetes, hypertension, tobacco use) and presence of comorbidities (CVD, asthma, cancer, immunosuppression and chronic kidney disease).

Results

The clinical characteristics of the cohort are described in table 1. Figure 1 represents the odds ratio and its 95% confidence interval of having the defined outcomes when presenting a ECG abnormality for the final regression model.

Conclusion

ECG abnormalities were independently related to poor outcomes in COVID-19 after accounting for multiple confounders. Significant associations were more frequently found for ischemic abnormalities, heart rate above 120 bpm, atrial fibrillation and having at least one major electrocardiographic abnormality.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): Pfizer and Sanofi PasteurWorld Heart Federation

Effects of illegal gold mining on Hg concentrations in water, Pistia stratiotes, suspended particulate matter, and bottom sediments of two impacted rivers (Paraíba do Sul River and Muriaé River), Southeastern, Brazil

Recent reports of illegal small-scale alluvial gold mining activities (locally called garimpo) by miners working on rafts in the Paraíba do Sul River (PSR) and in one of its tributaries (Muriaé River (MR)) have raised concerns about Hg contamination. This study aimed to evaluate the impact of garimpo activities on Hg contamination in three environmental compartments. Water, sediment, and aquatic macrophytes (Pistia stratiotes) were sampled during the rainy season in PSR, forming a 106-km transect from the point where garimpo rafts were seen and/or seized by the Federal Police. They were also sampled in the MR. Total and dissolved mercury (Hg) concentrations in water and total Hg in the suspended particulate matter (SPM) sampled in the PSR increased by 1.7, 1.5, and 2.1 times at the points where the rafts were seen compared to the point immediately upstream. In the MR, Hg concentrations were higher than those in the PSR, but most values in the environmental compartments were below the safe limits (174-486 ng∙g^-1, threshold and probable effect level, respectively), with the exception of Hg in the SPM of one of the MR sampling points (256 ng∙g^-1) and the mining tailings (197 ng∙g^-1). Sediment granulometry was exponentially associated with Hg concentrations in the sediment (R² = 0.75, p < 0.0001) and is also essential to understand the physical impacts of garimpo on PSR. Future studies should focus on assessing the seasonal variability of Hg concentrations in the studied compartments, especially if garimpo is identified during the dry season.

Remains of 137Cs contamination in the city of Goiânia, Brazil

The results of measurements, performed in 1999, of the remaining 137Cs contamination in some of the sites where fragments of a radioactive source of a teletherapy unit had been manipulated in 1987 are presented. This episode occurred in the city of Goiânia, during Brazil's worst radiological accident ever reported. Using the technique of gamma ray spectrometry, analyses of both surface and profile soil and vegetable samples were made. High values of 137Cs activity per unit mass were found in soil layers at depths between 10 and 40cm from the surface. Some values exceeded by up to eight times the action level of 22.5 kBq x kg(-1) proposed by the Brazilian National Nuclear Energy Commission (CNEN) during the decontamination process at the time of the accident, for the first year after the accident. Absorbed dose rates at 1 m above the ground were calculated from the data of 137Cs concentration in the soil and compared with those obtained from in situ gamma ray spectrometry and from thermoluminescence dosimetry.