On the other hand, a reduction in acute toxicity to C. Of a total of 12 samples taken from the Antas reservoir, the frequency of acutely toxic samples was greater for C. According to the PCA Fig. In July , considering the sampling sites from the Antas reservoir, the PCA indicated a tendency for a strong correlation with the high percentage of immobility for the species C. The results of the experiments that evaluated the survival potential of the species C. This study provided a comprehensive ecotoxicological and chemical evaluation of a tropical reservoir influenced by uranium mining effluents.
In the present research, the average values for sulfate, hardness and manganese were higher in November than in February The low values for ions in the water from the Antas reservoir in the wet season February can be associated with the high rainfall and low water residence time. Rodgher et al.
Similar to the present study, Da Silva 37 found high concentrations of metals and sulfate in a stream close to a mining area in Portugal during periods of reduced rainfall. Gemici 38 also found seasonal fluctuations in the physical and chemical water quality data for streams in a mercury mine area in Turkey. Potentially toxic contaminants arising from agriculture, such as agricultural inputs and pesticides were not detected in this aquatic body.
The results of this study registered significant amounts of the ions fluoride, sulfate, manganese, zinc and uranium in the water. In the current study, the average suspended solids contents in the Antas reservoir were significantly higher in the wet season October than the values observed in the dry season July Research has shown that the contribution of suspended matter coming from the banks of the Antas reservoir and the occurrence of resuspension of the material found in the sediment to the water column was much greater in the rainy season than in the dry season, indicating a positive correlation between the rainfall and the suspended matter in the reservoir 9.
The release of effluents, naturally enriched with metals and radionuclides, is the main legacy of uranium mines. The uranium concentrations found in the Antas reservoir are equivalent to the concentrations measured in aquatic ecosystems impacted by U mining, while the Al, Fe and Mn levels were higher The results of the physical and chemical parameters determined in the water samples from the Antas reservoir also showed that the sulfate, manganese, fluoride, uranium and aluminum concentrations exceeded the maximum levels according to the Brazilian limits 24 , The elevated concentrations of the chemical species recorded in the sediment samples at the Antas reservoir revealed contamination by uranium mining effluents, as also observed in the water samples in the current study.
In July , a greater frequency of samples toxic for C. Based on the principal components analysis Fig. In November , the extremely high average value for hardness On the other hand, in July , when elevated concentrations of the chemical species were registered and the average value for hardness indicated soft water In the literature there is little information related to the influence of water hardness in the expression of metal toxicity in environmental samples. The results for acute toxicity registered in the present study in November and July confirmed those of Yim et al.
It is known that water hardness affects the toxicity of various metals in many aquatic species 47 , Water hardness is a chemical characteristic that depends on the occurrence of alkaline earth metals, mainly calcium and magnesium elements. This feature is due to the dissolution of minerals in soils, and can also be associated with pollution by industrial effluents The survival of C. Thus the results indicated that extremely high hardness values were not limiting for the survival of the cladocerans.
Acute toxicity for D. Major cations may compete with trace metals such as fluoride and sulfate for target cell sites and are known to modify their toxicity for aquatic organisms 44 , Kinraide et al. On the other hand, Goulet et al. Instead it appeared that the increase in Ca, Mg and sulfate increased the tolerance of the aquatic organisms to U.
Similarly, Shamsollahi et al. Data from the present study clearly showed that the variation in water hardness considerably altered the toxicity of the Antas reservoir samples to the cladocerans during the year. The toxicity bioassay with C. On the other hand, a reduction in acute toxicity for C.
These acute toxicity results agreed with the spatial distribution of the concentrations of uranium, sulfate and fluoride, and with the electrical conductivity values at PE near the site where the mining effluent was discharged , which were higher than those at CAB and P In this study the toxicity bioassays indicated that a large proportion of the water samples collected at PE and P14 had toxic effects on C. The treated effluent samples were positively correlated with elevated concentrations of uranium, manganese, aluminum, zinc and fluoride and with high electrical conductivity and pH values.
In addition, the results of the acute toxicity registered at PS did not conform with the standards for the discharge of effluent into the environment, according to the Conama Resolution The current Brazilian Conama Resolution 25 prescribes that the effluent of a polluting source must not cause or present potential to cause toxic effects to aquatic organisms in freshwater bodies. The concentrations of the chemical species manganese, fluoride, sulfate and uranium at the following sites: PS treated effluent before being discharged into the environment , PE and P14 Antas reservoir , may represent a risk to invertebrate species.
Thus one must discussion toxicity for aquatic invertebrates under different physical and chemical conditions, since environmental variables e. The environmental variables e. Hyalella azteca , Ceriodaphnia silvestrii Lemna minor , Chironomus dilutes , Clorella sp. Freshwater invertebrates in general and daphnids in particular, have been widely used in ecotoxicological studies of freshwater reservoirs contaminated with anthropogenic toxic substances from mining activities.
Chen et al. Water hardness is a very variable factor, depending on which geochemical region of the world is involved. Daphnia magna is a native microcrustacean from Europe, where the natural water contains high carbonate values Thus D. However, the geographical distribution of D. From the viewpoint of ecotoxicity bioassays, it is more adequate to use native species than to import non-indigenous species. In Brazil, the cladoceran C.
These results confirm the importance of carrying out acute toxicity tests using an indigenous species such as C. The survival potential of C. This study highlights the usefulness of the ecotoxicological approach associated with the chemical approach as an effective tool to evaluate critical areas within aquatic ecosystems potentially impacted by U discharges into the environment.
A clearly protective effect to the acute toxicity of the metals in the water from the Antas reservoir was provided to the cladocerans C. Friese, K. In: Acidic Pit Lakes. Geller, W. Carvalho, F. Antunes, S. Acute and chronic toxicity of effluent water from an abandoned uranium mine. Arch Environ. Rippon, G. Environmental impact assessment of tailings dispersal from a uranium mine using toxicity testing protocols.
Water Resour. Pyle, G. The influence of water hardness, pH, and suspended solids on nickel toxicity to larval fathead minnows Pimephales promelas. Water Air Soil Pollut. Robertson, E. Bioassays with caged Hyalella azteca to determine in situ toxicity downstream of two Saskatchewan, Canada, uranium operations.
Gajski, G. Hudcova, H. Mining methods, tailings and run-off management and land rehabilitation are subject to Government regulation and inspection.
Mining operations are undertaken under relevant national health and radiation protection codes of practice. These set strict health standards for exposure to gamma radiation and radon gas. Standards apply to both workers and members of the public.
See associated paper: Occupational Safety in Uranium Mining. Solid waste products from the milling operation are tailings. They comprise most of the original ore and they contain most of the radioactivity in it. In particular they contain all the radium present in the original ore. At an underground mine they may be first cycloned to separate the coarse fraction which is used for underground fill. The balance is pumped as a slurry to a tailings dam, which may be a worked-out pit as at Ranger and McClean Lake.
When radium undergoes natural radioactive decay one of the products is radon gas. Because radon and its decay products daughters are radioactive and because the tailings are now on the surface, measures are taken to minimise the emission of radon gas. During the operational life of a mine the material in the tailings dam is often kept covered by water to reduce surface radioactivity and radon emission though with lower-grade ores neither pose a hazard at these levels.
On completion of the mining operation, it is normal for the tailings dam to be covered with some two metres of clay and topsoil to reduce radiation levels to near those normally experienced in the region of the orebody, and for a vegetation cover to be established.
At Ranger and Jabiluka in North Australia, tailings will be returned underground, as was done at the now-rehabilitated Nabarlek mine. In Canada, ore treatment is often remote from the mine that the new ore comes from, and tailings are emplaced in mined out pits wherever possible, and engineered dams otherwise.
The radon gas emanates from the rock and tailings as the radium or thorium decays. It then decays itself to solid radon daughters, which are significantly alpha radioactive. In the case of Ranger ore — with 0. When the ore is processed, the U and the very much smaller masses of U and the U are removed. The controlling long-lived isotope then becomes Th which decays with a half life of 77, years to radium followed by radon Radon occurs in most rocks and traces of it are in the air we all breathe.
However, at high concentrations it is a health hazard. A paper looks at the long-term population dose due to radon from uranium mining and shows that it is insignificant. Run-off from the mine stockpiles and waste liquors from the milling operation are collected in secure retention ponds for isolation and recovery of any heavy metals or other contaminants.
The liquid portion is disposed of either by natural evaporation or recirculation to the milling operation. Most Australian and many other mines adopt a "zero discharge" policy for any pollutants. Process water discharged from the mill contains traces of radium and some other metals which would be undesirable in biological systems downstream.
This water is evaporated and the contained metals are retained in secure storage. During the operational phase, such water may be used to cover the tailings while they are accumulating. With in situ leach ISL operations, the orebody stays in the ground, in a contained aquifer, and uranium is recovered by circulating oxygenated and acidified groundwater through it, using injection and recovery wells.
The saline quality of this groundwater in Australian ISL mines makes it far from potable in the first place, and after the uranium is recovered, oxygen input and circulation are discontinued, leaving the groundwater much as it was.
The main environmental consideration with ISL is avoiding pollution of any groundwater away from the orebody, and leaving the immediate groundwater no less useful than it was initially. Descriptions of how environmental management is undertaken at Australia's three uranium mines, Ranger, Olympic Dam, and Beverley are under the Environmental Management headings of Australia's Uranium Mines , in the sections on the respective mines.
In relation to Ranger, the Office of the Supervising Scientist was established by the Commonwealth Government in to oversee environmental protection at uranium mines in the Alligator Rivers region of the Northern Territory. Apart from tailings, other solid wastes at a mine include equipment which is not able to be sold at the end of the operation.
This is usually buried with the tailings. At the conclusion of mining, tailings are covered permanently with enough clay and soil to reduce both gamma radiation levels and radon emanation rates to levels near those naturally occurring in the region, and enough rock to resist erosion.
A vegetation cover is then established. Mary Kathleen in Queensland was the site of Australia's first major rehabilitation project of a uranium mine. It involved the plant site, a 28 hectare tailings dam, and a 60 ha evaporation pond area. All this has now returned to being a cattle station, with unrestricted access.
The Nabarlek uranium mine in the Northern Territory, c km east of Darwin, was the first of the "new generation" of uranium mines to commence operations and the first to be rehabilitated. Environmental protection was stressed at Nabarlek since before mining commenced, and everything proceeded with eventual rehabilitation very much in mind.
During the life of the operation the company worked together with government agencies, the Northern Land Council NLC and Aboriginal land owners to ensure a high standard of environmental management, culminating in its decommissioning and successful rehabilitation. At Ranger the planning of final restoration is well-established, and each year the company prepares a full-costed plan which assumes that mining could cease that year.
Uranium tailings on Department leases and other tracts have already contaminated the Dolores and San Miguel river watersheds, seriously degrading water quality in both rivers. Proposed uranium mines and mills in the area including the Whirlwind mine and the Paradox uranium mill may also result in runoff and discharge of contaminants into the Dolores River basin.
Get the latest on our work for biodiversity and learn how to help in our free weekly e-newsletter. Bonytail chub Colorado pikeminnow Humpback chub Razorback sucker. Silicosis causes scarring of the lung and severe breathing problems. The risk of these lung diseases was greater the longer miners had worked in the mine. This is about 4 times more deaths than expected. This could have been related to the silicosis. People with silicosis are more likely to get TB.
Some of this result could have been related to cigarette smoking. People who smoke are more likely to get emphysema. We expected to see about 68 deaths from injuries and found This is over 2 times more deaths than expected. Both of these categories had small numbers of deaths. Therefore, it is possible that the increased risk may not be due to mining. We expected deaths and found 1, We found strong evidence for an increased risk for lung cancer in non-white uranium miners.
We expected about 10 deaths, but found This means we found over 3 times more lung cancer deaths than expected. We also found strong evidence for pneumoconioses and other lung diseases other than cancer. We expected about 8 deaths, but found This category includes many different diseases.
They include silicosis. Because of the small study size of the non-white miners, we may have missed some other illnesses connected to this mining group. This study was not able to look at non-fatal injuries or at health problems that do not cause death. For example, they may still suffer from injuries that took place while mining.
Or they may suffer from breathing problems. However, we were not able to take these conditions into account. This study did not include uranium millers. This study will be completed in the years to come. They may have affected the health of community members other than workers. However, our study could not address these important issues. NIOSH made the study to find if uranium miners have an increased risk for lung cancer and other lung disease when compared to the U.
We found the following deaths were greater among white uranium miners compared to the general public:. Injuries — we expected about 68 deaths from injuries and found This was over 2 times more deaths than expected. We found the following deaths were greater among non-white uranium miners compared to the general public:.
Smoking greatly increases the risk of lung cancer and other lung disease in miners who breathed radon and dust. Smokers who quit now will reduce their risk even though they may have smoked for many years. Eat lots of fresh fruits and vegetables.
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