Geochemistry of acid mine drainage from a coal mining area and processes controlling metal attenuation in stream waters, southern Brazil

Journal of Environmental Radioactivity

Garcı́a-Tenorio

Francés

et al. 2017

The radio-elements U,U, U,Th, Th andPo were characterized in lichens, mosses and ferns species sampled in an adjacent coal mine area at Figueira City, Paraná State, Brazil, due to their importance for the assessment of human exposure related to the natural radioactivity. The coal is geologically associated with a uranium deposit and has been used as a fossil fuel in a thermal power plant in the city. Samples were initially prepared at LABIDRO (Isotopes and Hydrochemistry Laboratory), UNESP, Rio Claro (SP), Brazil. Then, alpha-spectrometry after several radiochemical steps was used at the Applied Nuclear Physics Laboratories, University of Seville, Seville, Spain, for measuring the activity concentration of the radionuclides. It was Po the radionuclide that most bio-accumulates in the organisms, reaching the highest levels in mosses. The ferns species were less sensitive as bio-monitor than the mosses and lichens, considering polonium in relation to other radionuclides. Fruticose lichens exhibited lower polonium content than the foliose lichens sampled in the same site. Besides biological features, environmental characteristics also modify the radio-elements absorption by lichens and mosses like the type of vegetation covering these organisms, their substrate, the prevailing wind direction, elevation and climatic conditions. OnlyPo and U correlated in ferns and in soil and rock materials, being particulate emissions from the coal-fired power plant the most probable U-source in the region. Thus, the biomonitors used were able to detect atmospheric contamination by the radionuclides monitored.

Section: Description Of the Study Areamentioning

confidence: 78%

Natural radionuclides in lichens, mosses and ferns in a thermal power plant and in an adjacent coal mine area in southern Brazil

Journal of Environmental Radioactivity

Garcı́a-Tenorio

Francés

et al. 2017

“…According to Depo et al (2008), the installation of filters and ash collectors in thermal power plants in Brazil has significantly reduced the emission of pollutants into the atmosphere. Despite that, Flues et al (2006) concluded that the coal combustion in the thermal power plant increases the radionuclide concentration in the atmospheric particulate matter by a factor of 5 to 10 times, which was corroborated by Campaner et al (2014) who found high activity concentrations of 238 U, 226 Ra, and 210 Pb in coal and its ashes and also in the topsoil of the region.…”

Section: Description Of the Study Areamentioning

confidence: 89%

“…This acid water accelerates and promotes elements and compounds leaching, and their transport to surface and groundwaters and the AMD generation was previously studied at the coal mining area in Figueira city, Paraná State, Southern Brazil, where toxic metals, such as As, are released to the waters as a result of the acid effluents (Campaner et al 2014;Galhardi and Bonotto 2016). Considering that the coal mined in Figueira city is enriched in uranium (Flues et al 2006), to investigate if the mining activities are capable to affect the natural waters in the area in terms of radiochemical parameters becomes essential.…”

Section: Introductionmentioning

confidence: 99%

Radionuclides (222Rn, 226Ra, 234U, and 238U) Release in Natural Waters Affected by Coal Mining Activities in Southern Brazil

Bonotto

2017

Water Air Soil Pollut

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.

“…It is a convenient groundwater reservoir as its basal portion comprises sandy material. Campaner andLuiz-Silva (2009) andCampaner et al (2014) investigated the AMD effects on soils, surface waters, and groundwaters from the Figueira city, checking the effluent quality after a treatment to the pH control by CaO addition. They found a pH increase in the surface waters downstream the mine that was attributed to carbonate minerals present in soils/rocks of the area and also to the CaO added in the tailings pile.…”

Section: Study Areamentioning

confidence: 99%

“…They found a pH increase in the surface waters downstream the mine that was attributed to carbonate minerals present in soils/rocks of the area and also to the CaO added in the tailings pile. Another finding was the increase in the toxic metals in the waters close to the mine (Campaner and Luiz-Silva 2009;Campaner et al 2014). …”

Section: Study Areamentioning

confidence: 99%

Hydrogeochemical features of surface water and groundwater contaminated with acid mine drainage (AMD) in coal mining areas: a case study in southern Brazil

Bonotto

2016

Environ Sci Pollut Res

Effects of acid mine drainage (AMD) were investigated in surface waters (Laranjinha River and Ribeirão das Pedras stream) and groundwaters from a coal mining area sampled in two different seasons at Figueira city, Paraná State, Brazil. The spatial data distribution indicated that the acid effluents favor the chemical elements leaching and transport from the tailings pile into the superficial water bodies or aquifers, modifying their quality. The acid groundwaters in both sampling periods (dry: pH 2.94-6.04; rainy: pH 3.25-6.63) were probably due to the AMD generation and infiltration, after the oxidation of sulfide minerals. Such acid effluents cause an increase of the solubilization rate of metals, mainly iron and aluminum, contributing to both groundwater and surface water contamination. Sulfate in high levels is a result of waters' pollution due to AMD. In some cases, high sulfate and low iron contents, associated with less acidic pH values, could indicate that AMD, previously generated, is nowadays being neutralized. The chemistry of the waters affected by AMD is controlled by the pH, sulfide minerals' oxidation, oxygen, iron content, and microbial activity. It is also influenced by seasonal variations that allow the occurrence of dissolution processes and the concentration of some chemical elements. Under the perspective of the waters' quality evaluation, the parameters such as conductivity, dissolved sodium, and sulfate concentrations acted as AMD indicators of groundwaters and surface waters affected by acid effluents.