Environmental and occupational health on the Navajo Nation: a scoping review

A scoping review was performed to answer: what environmental health concerns have been associated with adverse health outcomes in the Navajo Nation? The review focused on occupational and ambient environmental exposures associated with human industrial activities. The search strategy was implemented in PubMed, and two investigators screened the retrieved literature. Thirteen studies were included for review. Data were extracted using the matrix method. Six studies described associations between work in uranium mining and cancer. Six studies focused on environmental exposures to uranium mine waste and other metals, with outcomes that included biological markers, kidney disease, diabetes and hypertension, and adverse birth outcomes. One study explored occupational exposure to Sin Nombre Virus and infection. Most research has focused on the health effects of uranium, where occupational exposures occurred among miners and environmental exposures are a legacy of uranium mining and milling. Gaps exist with respect to health outcomes associated with current occupations and the psychosocial impact of environmental hazards. Other environmental exposures and hazards are known to exist on the Navajo Nation, which may warrant epidemiologic research.

Application of radio-wave geointoscopy method to study the nature of spreading the solutions in the process of uranium underground leaching

Purpose. Assessment of the effectiveness of using the method of radio-wave geointoscopy of the inter-well space for three-dimensional mapping of the zone of the leaching solution actual propagation in the process of uranium mining by the method of underground leaching. Methods. Experimental-industrial studies of the leaching process are conducted at technological block 68 of the Semizbay deposit (Kazakhstan). In experimental studies, special equipment is used for conducting radio-wave geointoscopy. Inter-well measurements are performed using the RVGI-06 equipment. The observations are conducted in a fan pattern within the filter section. The step between adjacent points along the wellbore is 1 m. At different stages of mining the technological block, maps of geoelectric resistivity have been compiled, with the help of which a comparative analysis is performed. Findings. A tendency to an increase in the area of acidic solutions propagation over time has been revealed by comparing the fragments of RVGI geoelectric map at different stages of mining the block. The influence of a heterogeneous geological structure on the uniformity of the leaching solutions propagation has been proved. It has been determined that the resolving power of the radio-wave geointoscopy method is sufficient to detect changes in geoelectric conditions at small monitoring cycles in time. The spatial-temporal change in the front of the leaching solutions propagation makes it possible to determine the prevailing directions of solutions propagation and to assess the filtration characteristics of rocks. Originality. The patterns have been determined of the leaching solutions propagation over time from the beginning of block acidification to active leaching. The first attempts have been made to use the geophysical well logging method in the practice of uranium mining by In-Situ Leaching (ISL) method. Practical implications. Monitoring studies by radio-wave geointoscopy method at the stage of passive acidification can be re-commended for further experimental and scientific testing at technological blocks of the Semizbay deposit for a quantitative assessment of the filtration characteristics of rocks and the dynamics of the acidification process development, as well as for the development of well-grounded recommendations on the optimal scheme for mining the blocks in specific geotechnical conditions.

An assessment of uranium in groundwater in the Grand Canyon region

The Grand Canyon region in northern Arizona is a home or sacred place of origin for many Native Americans and is visited by over 6 million tourists each year. Most communities in the area depend upon groundwater for all water uses. Some of the highest-grade uranium ore in the United States also is found in the Grand Canyon region. A withdrawal of over 4000 km2 of Federal land in the Grand Canyon region from new uranium mining activities for 20 years was instituted in 2012, owing in part to a lack of scientific data on potential effects from uranium mining on water resources in the area. The U.S. Geological Survey has collected groundwater chemistry samples since 1981 in the Grand Canyon region to better understand the current state of groundwater quality, to monitor for changes in groundwater quality that may be the result of mining activities, and to identify "hot spots" with elevated metal concentrations and investigate the causes. This manuscript presents results for the assessment of uranium in groundwater in the Grand Canyon region. Analytical results for uranium in groundwater in the Grand Canyon region were available for 573 samples collected from 180 spring sites and 26 wells from September 1, 1981 to October 7, 2020. Samples were collected from springs issuing from stratigraphic units above, within, and below the Permian strata that host uranium ore in breccia pipes in the area. Maximum uranium concentrations at groundwater sites in the region ranged from less than 1 µg/L at 23 sites (11%) to 100 µg/L or more at 4 sites (2%). Of the 206 groundwater sites sampled, 195 sites (95%) had maximum observed uranium concentrations less than the U.S. Environmental Protection Agency’s Maximum Contaminant Level of 30 µg/L for drinking water and 177 sites (86%) had uranium concentrations less than the 15 µg/L Canadian benchmark for protection of aquatic life in freshwater. The establishment of baseline groundwater quality is an important first step in monitoring for change in water chemistry throughout mining lifecycles and beyond to ensure the health of these critical groundwater resources.

Global uranium market imbalance will intensify

Significance By September, the spot price of uranium had surged to USD50 per pound (USD110 per kilogram), the highest since 2015. It remains above USD44. Sprott currently holds 24 million pounds of uranium, equivalent to 20% of annual mining production. Impacts Kazatomprom, the world’s largest uranium miner, is investing in a new physical uranium fund, ANU Energy, with plans to raise USD500mn. The Biden administration is taking steps to establish a US uranium reserve,originally proposed by the previous administration. Russia's plans to raise its share in global nuclear energy from about 20% to 25% by 2045, requiring completion of 24 new reactors. Westinghouse has reached an agreement to build nuclear reactors in Ukraine. Greenland's new left-leaning government is preparing legislation that will ban uranium mining.

Hydrogeology Response to the Coordinated Mining of Coal and Uranium: A Transparent Physical Experiment

The migration of fracture and leaching solute caused by mining activity is critical to the hydrogeology. To characterize liquid and solid migration in a mining area of intergrown resources, the coordinated mining of coal and uranium was considered, and a physical experiment based on transparent soil was conducted. A well experimental performance of transparent soil composed of paraffin oil, n-tridecane, and silica gel and the leaching solution comprised of saturated oil red O dye was observed for hydrogeology characterization. An “arch-shaped” fracture zone with a maximum height of 90 m above the mined goaf and a “horizontal-shaped” fracture zone with a fractured depth of 9.97–16.09 m in the uranium-bearing layer were observed. The vertical leachate infiltration of 4.83 m was observed in the scenario of uranium mining prior to coal, which is smaller than those in the scenarios of comining of coal and uranium (10.26 m) and coal mining prior to uranium (16.09 m). A slight strata movement below the uranium was observed, and the leaching solution infiltration in the coal mining area was not observed in a short period in the scenario of uranium mining prior to coal; both of those was presented in the scenarios of comining of coal and uranium and coal mining prior to uranium.

Hygienic assessment of personnel working conditions in underground uranium mining

The aim of the study is to assess the main radiation-hazardous factors that determine the effective dose of personnel during underground uranium mining at the Priargunsky Industrial Mining and Chemical Association, and to summarize the data of the radiation control of the enterprise for 2016-2020. The main factors that create personnel dose loads are: the volume activity of short-lived daughter products of radon decay in the air, the dose rate of external gamma radiation, and the volume activity of long-lived alpha-emitting radionuclides of the uranium-radium series in industrial dust. Information on the structure and values of individual effective doses of workers is presented. Recommendations for improving the radiation monitoring system are given.

Justification of Remediation Criteria of Uranium Legacy Sites

Purpose: To present approaches to establishing the criteria for remediation of sites contaminated due to past activities of uranium mining and milling facilities. These facilities are considered today as uranium legacy. Results: This paper presents the justified reference levels expressed in terms of annual effective dose values, which are recommended for using as remediation criteria for sites contaminated due to past activities of uranium mining and milling facilities (uranium legacy sites). Depending on further use of the sites after remediation, these criteria range from 1 µSv/year, in case of temporary presence of the population, to 10 µSv/year, in case of permanent residence of the population and conducting economic activities. Conclusions: In accordance with the international basic safety standards, accepted more than 10 years ago, exposure situations from radioactive material retained from previous activities refer to the existing exposure situation. Nevertheless, neither Federal Law “On Radiation Safety of the Population” nor Radiation Safety Standards have so far introduced terms “existing exposure situation” covering exposure at nuclear and uranium legacy sites and “reference level”, which is used to assure radiation safety of the population living at legacy sites or using these sites for the purpose of the economic activities.

Methods for intensification of borehole uranium mining at the fields with low filtration characteristics of ores

Purpose. Improving the efficiency of borehole uranium mining and the selection of special decolmating solutions to improve the filtration characteristics of the seam due to effective destruction, as well as by preventing the sedimentation in the productive horizon, depending on the mineralogical composition and structure of sediment-forming materials. Methods. The advantages and disadvantages of the main methods used for improving the filtration characteristics of the productive horizon, when mining the uranium deposits by the borehole method, have been studied. Samples of sedimentation from the productive horizon are taken at the uranium deposit of the Shu-Syrasu depression. The quantitative and qualitative parameters, as well as the peculiarities of the mineral compositions have been determined by the X-ray phase method. A methodology has been developed and laboratory experiments have been conducted on the treatment of sedimentation samples by the drop method using various compositions of selected decolmating solutions. The microscopic method is used to determine the structure and peculiarities of sedimentation before and after treatment with various decolmating solutions. Findings. The effectiveness of the main methods used to improve the filtration characteristics of seams in the uranium deposits, mined by the borehole method, has been determined. The structure and composition of sedimentation, which causes a decrease in the filtration characteristics of the productive horizon, have been determined. To destroy and prevent the sedimentation in the productive horizon, an effective composition of a special decolmating solution using ammonium hydrogen fluoride with the addition of sulphuric acid and surfactants has been selected. An effective method for increasing the filtration characteristics of the productive horizon with the use of special decolmating solutions has been developed and scientifically substantiated. Originality. The use of special decolmating solutions based on ammonium hydrogen fluoride with the addition of sulphuric acid and surfactants according to the developed methodology allows to effectively destroy and prevent sedimentation in the productive horizon of borehole uranium ore mining. Practical implications. The use of the developed decolmating solution and a special methodology for the intensification of borehole uranium mining can reduce the operating costs of its production. This increases the ecological and industrial safety of the work to intensify the leaching of uranium ores.