Radionuclides release to three rivers by ore treatment unit at Caldas, Minas Gerais-Brazil (original) (raw)
Related papers
Release of Uranium by an Ore Treatment Unit at Caldas, MG, Brazil
Journal of Environmental Protection, 2013
This study aims to assess the behavior of the release of U nat (i.e. uranium isotopes in natural relative abundance) from the release of water treated by the Ore Treatment Unit (UTM) in Caldas, state of Minas Gerais, Brazil, during the years 1999 to 2009. During this period, the unit showed no industrial activity, except between 2004 and 2005, when UTM operated 400 tons of monazite in a process to obtain rare earths. U nat was analyzed by spectrophotometry once per week in the effluent waters at sampling point 014. Two fractions were considered for analysis: the soluble one (that passes through a 0.45 µm filter) and the particulate one (retained on a 0.45 µm filter). Statistical analyses were performed: the "Z" test and Pearson's r 2 correlation index. The values for the soluble fraction were consistently lower than those of the particulate fraction and no statistically significant correlation was observed between the soluble and particulate fractions. However, the particulate and the total fractions (the sum of soluble and particulate) strongly correlated.
The Ore Treatment Unit (OTU) is located at the source of three rivers: Ribeirão das Antas, Ribeirão do Soberbo and Córrego da Consulta. Each interface of installation with the environment, at the tree rivers, has been monitored for the release of radionuclides. At Ribeirão das Antas a weekly sample collection was made at point 014. At Ribeirão Soberbo there was a weekly sample collection at point 025, and at Córrego da Consulta a monthly collection was carried out at point 076. This work analyses the average annual releases of uranium from the historical series started in 1999 and ended in 2011. Points 014 and 025 showed average release of 0.12 Bq L-1. Point 076 showed somewhat higher average release, 1.27 Bq L-1. An ANalysis Of VAriance test (ANOVA) has been carried out to verify the existence of different means between these collecting points. The averages were considered statistically different. As a complementary analysis, the Student's t test was performed between the averages at considered points. Between points 014 and 025, the averages were considered identical. Between points 014 and 076, the average release at point 076 was considered higher than that at point 014. The same behavior was observed between points 025 and 076. The releases at point 076 were considered higher than those at point 025. Thus it can be concluded that releases at points 014 and 025 are identical and both are lower than releases at point 076.
Water, Air, & Soil Pollution, 2017
Water quality was evaluated in a coal mining area in the city of Figueira, Paraná State, Brazil, where uranium was associated with the coal deposit. Upstream the mine, groundwaters were more acid and some elements and compounds, such as iron, aluminum, and sulfate, were in higher concentration, possibly because of acid mine drainage (AMD) generation in tailing pit. 238 U and 234 U activity concentrations exceeded the standards proposed by the World Health Organization in two sampling periods in effluent samples and in some groundwater samples, indicating that waters from this aquifer system were unhealthy for human consumption. Uranium isotopes were more elevated in groundwaters in the rainy month probably because of a higher leaching and transport rate of this element from rocks/ tailings pit to waters. The average radon activity concentration in groundwater was higher than in surface waters and effluents in both periods studied, possibly due to the enhanced presence of uranium and radium in the aquifer rocks that would favor the radon accumulation and entrapment. The effects of the mining activities on the groundwater quality were displayed in terms of activity ratios (234 U/ 238 U, 226 Ra/ 238 U), which showed different behaviors upstream the mine area relatively to areas downstream the mine.
Bulletin of Environmental Contamination and Toxicology, 2009
Two large uranium mines, Quinta do Bispo and Cunha Baixa, district of Viseu, North of Portugal, were exploited until 1991. Sulfuric acid was used for in situ uranium leaching in Cunha Baixa mine and for heap leaching of low grade ores at both mines. Large amounts of mining and milling residues were accumulated nearby. Since closure of mines, the treatment of acid mine waters has been maintained and treated water is released into surface water lines. Analysis of radionuclides in the soluble phase and in the suspended matter of water samples from the uranium mines, from the creeks receiving the discharges of mine effluents, from the rivers and from wells in this area, show an enhancement of radioactivity levels. For example, downstream the discharge of mine effluents into Castelo Stream, the concentrations of dissolved uranium isotopes and uranium daughters were up to 14 times the concentrations measured upstream; 238 U concentration in suspended particulate matter of Castelo Stream reached 72 kBq kg -1 , which is about 170 times higher than background concentrations in Mondego River. Nevertheless, radionuclide concentrations decreased rapidly to near background values within a distance of about 7 kilometers from the discharge point. Enhancement of radioactivity in underground waters was positively correlated with a decrease in water pH and with an increase of sulfate ion concentration, pointing out to Cunha Baixa mine as the source of groundwater contamination. The radiotoxic exposure risk arising from using these well waters as drinking water and as irrigation water is discussed and implementation of environmental remediation measures is advised.
Radioactivity in Iberian Rivers with Uranium Mining Activities in their Catchment Areas
Procedia Earth and Planetary Science, 2014
Rivers flowing through the uranium mining region of Portugal, such as the Mondego and Zêzere rivers, receive drainage from areas of old uranium mines. The international River Águeda, a tributary to River Douro, has also important uranium mining and milling facilities in its catchment basin in Spain. In order to assess the radioactive contamination of these river basins resulting from uranium mining waste, uranium series radionuclides were measured in water, suspended particulate matter, and riverbed sediments. Results showed that significant radioactivity enhancement took place in sections of these rivers. This contamination persisted long time after environmental remediation implemented at some mine sites and cessation of mine discharges. The persistent risk of waste leaching and dam failure requires continued monitoring of radioactivity levels in these rivers.
Radionuclides in underground water in an area contaminated with uranium mill waste
Uranium in the Aquatic Environment, 2002
The uranium mine and mill at Žirovski vrh (RŽV), Slovenia stopped mining and milling in 1990. Mill tailings containing about 20 % moisture were transported to a disposal site called Boršt. The objective of this work was to study the migration of the radionuclides U-238, Ra-226, Pb-210 and Po-210 from the Boršt waste disposal site. For determination of radionuclides, gamma and alpha spectrometry, beta counting, neutron activation analysis and liquid scintillation techniques were used.
Zenodo (CERN European Organization for Nuclear Research), 2015
Coal is an important non-renewable energy source of and can be associated with radioactive elements. In Figueira city, Paraná state, Brazil, it was recorded high uranium activity near the coal mine that supplies a local thermoelectric power plant. In this context, the radon activity (Rn-222, produced by the Ra-226 decay in the U-238 natural series) was evaluated in groundwater, river water and effluents produced from the acid mine drainage in the coal reject dumps. The samples were collected in August 2013 and in February 2014 and analyzed at LABIDRO (Laboratory of Isotope and Hydrochemistry), UNESP, Rio Claro city, Brazil, using an alpha spectrometer (AlphaGuard) adjusted to evaluate the mean radon activity concentration in five cycles of 10 minutes. No radon activity concentration above 100 Bq.L-1 , which was a previous critic value established by the World Health Organization. The average radon activity concentration in groundwater was higher than in surface water and in effluent samples, possibly due to the accumulation of uranium and radium in the aquifer layers that favors the radon trapping. The lower value in the river waters can indicate dilution and the intermediate value in the effluents may indicate radon absorption in the coal particles of the reject dumps. The results also indicate that the radon activities in the effluents increase with the sample acidification, possibly due to the higher radium leaching and the subsequent radon transport to the drainage flow. The water samples of Laranjinha River and Ribeirão das Pedras stream, which, respectively, supply Figueira city and receive the mining effluent, exhibited higher pH values upstream the mine, reflecting the acid mine drainage discharge. The radionuclides transport indicates the importance of monitoring their activity concentration in natural waters due to the risks that the radioactivity can represent to human health.
Journal of Radioanalytical and Nuclear Chemistry, 2013
The Metropolitan Region of Recife (MRR), Pernambuco State, Brazil, is well supplied in groundwater resources, mainly because of the water quality and exploitation capability of the Beberibe aquifer. The MRR is also located over uranium-bearing phosphate deposits of the coastal region of the Northeastern Brazil. Such sedimentary rocks present U3O8 content of 30–500 mg kg-1 (average of 150 mg kg-1), being considered one of the highest occurrences of this kind of deposit in the world. The mineral water recharging areas, when in contact with the uranium-phosphate rocks, may increase the radioactive contamination of water due to the leaching and transport of U and other radioactive chemical elements from the rocks to the groundwater. Taking into account the continuous increasing of production and preferential drinking of bottled mineral water in the region, notoriously in the last decade, this study encompassed the first results of gross alpha and beta activities in the bottled mineral water of the MRR. The determination of the alpha and beta activities was carried out in nine commercial mineral water brands from springs located in different regions over the Beberibe aquifer, using a low background gas flowproportional counter, model Canberra S5-XLB. The methodology consisting of concomitant water evaporation steps in planchets was modified from the standard methods for the examination of water and wastewater. The levels of activities ranged from (35 ± 3) to (85 ± 5), and (200 ± 9) to (330 ± 8) mBq L-1 for the gross alpha and beta activities, respectively. A consistent spatial variation in the radioactivity levels in mineral water was observed for MRR springs, in which radiation decreased according to the increasing of distance from theMRRarea. Since outcrops of phosphate rocks containing uranium have been already detected in the urban area, mineral water resources within the MRR might be in contact with uranium enriched rocks in the deeper geological layers. Even though, the risk of radioactive contamination was considered low because the gross alpha and beta activity concentrations were in accordance with the World Health Organization water potability standards of 500 and 1,000 mBq L-1, respectively.
Chemosphere, 2011
The present work studied the radioacitivity impact of a coal-fired power plant (CFPP), a NORM industry, on the water of the Regallo river which the plant uses for cooling. Downstream, this river passes through an important irrigated farming area, and it is a tributary of the Ebro, one of Spain's largest rivers. Although no alteration of the 210 Po or 232 Th content was detected, the 234,238 U and 226 Ra contents of the water were significantly greater immediately below CFPP's discharge point. The 226 Ra concentration decreased progressively downstream from the discharge point, but the uranium content increased significantly again at two sampling points 8 km downstream from the CFPP's effluent. This suggested the presence of another, unexpected uranium source term different from the CFPP. The input from this second uranium source term was even greater than that from the CFPP. Different hypotheses were tested (a reservoir used for irrigation, remobilization from sediments, and the effect of fertilizers used in the area), with it finally being demonstrated that the source was the fertilizers used in the adjacent farming areas.