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Alvarado, J. A. C., Balsiger, B., Röllin, S., Jakob, A., & Burger, M. (2014). Radioactive and chemical contamination of the water resources in the former uranium mining and milling sites of Mailuu Suu (Kyrgyzstan). Journal of Environmental Radioactivity, 138, 1–10.
Abstract: An assessment of the radioactive and chemical contamination of the water resources at the former uranium mines and processing sites of Mailuu-Suu, in Kyrgyzstan, was carried out. A large number of water samples were collected from the drinking water distribution system (DWDS), rivers, shallow aquifers and drainage water from the mine tailings. Radionuclides and trace metal contents in water from the DWDS were low in general, but were extremely high for Fe, Al and Mn. These elements were associated with the particle fractions in the water and strongly correlated with high turbidity levels. Overall, these results suggest that water from the DWDS does not represent a serious radiological hazard to the Mailuu Suu population. However, due to the high turbidities and contents of some elements, this water is not good quality drinking water. Water from artesian and dug wells were characterized by elevated levels of U (up to 10 μg/L) and some trace elements (e.g. As, Se, Cr, V and F) and anions (e.g. Cl−, NO3−, SO42−). In two artesian wells, the WHO guideline value of 10 μg/L for As in water was exceeded. As the artesian wells are used as a source of drinking water by a large number of households, special care should be taken in order to stay within the WHO recommended guidelines. Drainage water from the mine tailings was as expected highly contaminated with many chemicals (e.g. As) and radioactive contaminants (e.g. U). The concentrations of U were more than 200 times the WHO guideline value of 30 μg/L for U in drinking water. A large variation in 234U/238U isotopic ratios in water was observed, with values near equilibrium at the mine tailings and far from equilibrium outside this area (reaching ratios of 2.3 in the artesian well). This result highlights the potential use of this ratio as an indicator of the origin of U contamination in Mailuu Suu.
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Salbu, B. (2013). Preface: uranium mining legacy issue in Central Asia. Journal of Environmental Radioactivity, 123, 1–2.
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Pastukhov, A. M., Rychkov, V. N., Smirnov, A. L., Skripchenko, S. Y., & Poponin, N. A. (2014). Purification of in situ leaching solution for uranium mining by removing solids from suspension. Minerals Engineering, 55, 1–4.
Abstract: This study investigated the process of in situ leaching (ISL) method of uranium mining, and the removal of solid particles from the leaching solution. Investigations were carried out for 4months. The content of firm suspensions in the productive solutions arriving from the well field was up to standard of 3–5mg/l. After keeping in a settler of productive solutions within one hour concentration of suspensions decreases to 2–2.5mg/l. To increase the life of the wells requires more fine purification of the ISL solutions. The best results can be obtained but using filtration. Bag filters were used in experiments carried out at the extraction site. All samples of polypropylene bag filter was produced by the Tamfelt Corporation. The best results were obtained for fabrics S-51M03-L2K4 (pore size 3μm). After three month of trials following indicators of wells work were fixed: on the trial cell decrease in intake capacity did not occur; on the other cells of well field injectability of holes for the same period of time decreased for 15–40%. The results illustrated the high efficiency of this method, which allows injection wells to reach a constant intake capacity, making it possible for technological cells to achieve a constant productivity and balance. Purification of solutions allows to reduce acidulation term of new technological cells from 3–4 to 1.5–2months.
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Tujchneider, O., Christelis, G., & Gun, J. V. der. (2013). Towards scientific and methodological innovation in transboundary aquifer resource management. Environmental Development, 7, 6–16.
Abstract: Groundwater is both an invaluable and a vulnerable resource. Aquifer resources management, aiming at the responsible exploitation and adequate protection of the groundwater resources, is therefore of key importance and has to be based on sound hydrological, environmental, economic and social principles. Aquifer-wide groundwater projects are carried out to collect the required area-specific information, to understand ongoing processes, to identify the management issues to be addressed and to develop an adequate management strategy and action plan. The quality of the project results depends to a large extent on the science and methodologies adopted in the design and used during the implementation of the projects. In this context, a project was carried out recently to analyse the scientific aspects of—among others—the transboundary aquifer projects within the IW: Portfolio of the Global Environmental Facility (GEF) and to make recommendations for scientific strengthening and innovation. This paper presents the main outcomes of this analysis. In order to accomplish groundwater resources management goals in the case of transboundary aquifers, a balanced joint strategy is needed. Analysis of documentation on completed and on-going transboundary aquifer projects has shown a wide range of scientific activities that contribute positively to the development of such strategies. This analysis has also identified options for increasing the positive impacts of science on strategy development; some of these options have been pioneered already and deserve wider application other ones are relatively new. Important options are: integrating transboundary aquifer resource management in a wider environmental–socio-economical context (holistic approach); exploring causal chains to better understand the processes of change of groundwater resources; using this improved understanding for optimising groundwater assessment and monitoring programmes; and adaptive management. In addition, to obtain maximum benefit of the scientific results there is a general need to promote effective communication at all levels, between the scientific community and policy-/decision makers, as well as with the local community who have a major role to play in the use and conservation of the resources. All of this should be accompanied by the harmonisation of the legal instruments and co-operation agreements between countries and the communities involved. Two case studies, one in South America and one in Southern Africa, are added as examples of the setting and approach of the analysed transboundary aquifer projects.
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Botha, R., Lindsay, R., Newman, R. T., Maleka, P. P., & Chimba, G. (2019). Radon in groundwater baseline study prior to unconventional shale gas development and hydraulic fracturing in the Karoo Basin (South Africa). Applied Radiation and Isotopes, 147, 7–13.
Abstract: The prospect of unconventional shale gas development in the semi-arid Karoo Basin (South Africa) has created the prerequisite to temporally characterise the natural radioactivity in associated groundwater which is solely depended on for drinking and agriculture purposes. Radon (222Rn) was the primary natural radionuclide of interest in this study; however, supplementary radium (226Ra and 228Ra) in-water measurements were also conducted. A total of 53 aquifers spanning three provinces were studied during three separate measurement campaigns from 2014 to 2016. The Karoo Basin’s natural radon-in-water levels can be characterised by a minimum of 1 ± 1 Bq/L (consistent with zero or below LLD), a maximum of 183 ± 18 Bq/L and mean of 41 ± 5 Bq/L. The mean radon-in-water levels for shallow aquifers were systematically higher (55 ± 10 Bq/L) compared to deep (14 ± 3 Bq/L) or mixed aquifers (20 ± 6 Bq/L). Radon-in-water activity concentration fluctuations were predominantly observed from shallow aquifers compared to the generally steady levels of deep aquifers. A collective seasonal mean radon-in-water levels increase from the winter of 2014 (44 ± 8 Bq/L) to winter of 2016 (61 ± 16 Bq/L) was noticed which could be related to the extreme national drought experienced in 2015. Radium-in-water (228Ra and 226Ra) levels ranged from below detection level to a maximum of 0.008 Bq/L (226Ra) and 0.015 Bq/L (228Ra). The 228Ra/226Ra ratio was characterised by a minimum of 0.93, a maximum of 6.5 and a mean value of 3.3 ± 1.3. Developing and improving baseline naturally occurring radionuclide groundwater databases is vital to study potential radiological environmental impacts attributed to industrial processes such as hydraulic fracturing or mining.
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Burchi, S. (2018). Legal frameworks for the governance of international transboundary aquifers: Pre- and post-ISARM experience. Journal of Hydrology: Regional Studies, 20, 15–20.
Abstract: Study region Africa, Latin America, Europe. Study focus Through the extensive study and mapping of the world’s aquifers that lie astride the international boundary lines of sovereign States, ISARM has awakened concerned States to the existence of aquifers stretching beyond their borders, and precipitated cooperation in generating a body of knowledge that facilitated cooperation in governance arrangements for such aquifers. In parallel, ISARM influenced the shape and direction of the United Nations “Draft articles on the law of transboundary aquifers” appended to UN Resolution 63/124 of 2008. Both stimulated cooperation among concerned States, and provided a frame of reference for the legal grounding of such cooperation in aquifer-specific agreements. New hydrological insights Through this synergistic paradigm, ISARM has made an impact on the shape and direction of cooperation in the Guaraní Aquifer in South America, and in the Iullemeden and Taoudeni/Tanezrouft Aquifer Systems (ITAS) in the Sahel region of Africa. It is having an influence on the shape and direction of cooperation being negotiated on the Stampriet Aquifer System in Southern Africa, and on the Ocotepeque-Citalá Aquifer in Central America. The link of ISARM to other international aquifer agreements on record is tenuous, and ISARM’s influence on their generation speculative. The visibility of ISARM has faded since 2012, however its legacy is lasting.
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Nijsten, G. - J., Christelis, G., Villholth, K. G., Braune, E., & Gaye, C. B. (2018). Transboundary aquifers of Africa: Review of the current state of knowledge and progress towards sustainable development and management. Journal of Hydrology: Regional Studies, 20, 21–34.
Abstract: Study region Transboundary aquifers (TBAs) of Africa. Study focus Review of work on TBAs in Africa, including an overview of assessments and management efforts that have taken place over the last half century. New hydrological insights Seventy-two TBAs have been mapped in Africa. They underlie 40% of the continent, where 33% of the population lives, often in arid or semi-arid regions. TBA inventories have progressed since 2000 and remain work in progress. Despite their importance only eleven TBAs have been subjected to more detailed studies. Cooperation has been formalised for seven TBAs. Most of these TBAs are in North Africa and the Sahel. The recent global Transboundary Waters Assessment Programme compiled information at the national level to describe TBAs in terms of key indicators related to the water resource, socio-economic, and legal and institutional conditions. Availability of data at national level is low, hampering regional assessment. Comparing indicators, from questionnaire surveys, with those from a global water-use model showed variable levels of agreement, calling for further research. Reports on agreements scoping TBA management, indicate that this may be dealt with within international river/lake agreements, but reported inconsistencies between TBA sharing countries also indicate that implementation is limited. Increasing awareness and support to joint TBA management is noticeable amongst international organisations. However, such cooperation requires long-term commitment to produce impacts at the local level.
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Brook, G. A., Railsback, L. B., & Marais, E. (2011). Reassessment of carbonate ages by dating both carbonate and organic material from an Etosha Pan (Namibia) stromatolite: Evidence of humid phases during the last 20ka. Quaternary International, 229(1), 24–37.
Abstract: Previous research on lacustrine stromatolites from Etosha Pan in Namibia obtained ages on carbonate close to or beyond the limits of radiocarbon dating. These ages suggested that the basin was likely not subject to extensive flooding during the last ca. 40ka. This study shows that AMS radiocarbon ages for the carbonate of a stromatolite from Poacher’s Point are 15–21ka older than ages for organic material in the stromatolite structure. Calibrated ages range from 30 to 40ka for carbonate and 3–19ka for the organic residue. The new ages, together with petrographic and isotopic data for the stromatolite, have provided important new information on past flooding of Etosha Pan including evidence of prolonged lacustrine conditions during the Holocene Climatic Optimum.
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Silva, M. L. da, & Bonotto, D. M. (2015). Uranium isotopes in groundwater occurring at Amazonas State, Brazil. Applied Radiation and Isotopes, 97, 24–33.
Abstract: This paper reports the behavior of the dissolved U-isotopes 238U and 234U in groundwater providing from 15 cities in Amazonas State, Brazil. The isotope dilution technique accompanied by alpha spectrometry were utilized for acquiring the U content and 234U/238U activity ratio (AR) data, 0.01–1.4µgL−1 and 1.0–3.5, respectively. These results suggest that the water is circulating in a reducing environment and leaching strata containing minerals with low uranium concentration. A tendency to increasing ARs values following the groundwater flow direction is identified in Manaus city. The AR also increases according to the SW–NE directions: Uarini→Tefé; Manacapuru→Manaus; Presidente Figueiredo→São Sebastião do Uatumã; and Boa Vista do Ramos→Parintins. Such trends are possibly related to several factors, among them the increasing acid character of the waters. The waters analyzed are used for human consumption and the highest dissolved U content is much lower than the maximum established by the World Health Organization. Therefore, in view of this radiological parameter they can be used for drinking purposes.
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Edmunds, W. M., Shand, P., Hart, P., & Ward, R. S. (2003). The natural (baseline) quality of groundwater: a UK pilot study. Science of The Total Environment, 310(1), 25–35.
Abstract: Knowledge of the natural baseline quality of groundwaters is an essential prerequisite for understanding pollution and for imposing regulatory limits. The natural baseline of groundwaters may show a range of concentrations depending on aquifer mineralogy, facies changes, flow paths and residence time. The geochemical controls on natural concentrations are discussed and an approach to defining baseline concentrations using geochemical and statistical tools is proposed. The approach is illustrated using a flowline from the Chalk aquifer in Berkshire, UK where aerobic and anaerobic sections of the aquifer are separately considered. The baseline concentrations for some elements are close to atmospheric values whereas others evolve through time-dependent water–rock interaction. Certain solutes (K, NH4+), often considered contaminants, reach naturally high concentrations due to geochemical controls; transition metal concentrations are generally low, although their concentrations may be modified by redox controls. It is recommended that the baseline approach be incorporated into future management strategies, notably monitoring.
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