Mercury Levels in Groundwater near Artisanal Small-Scale Gold Mines in Migori County, Kenya
Abstract
In Migori County, artisanal and small-scale gold mining (ASGM) is an economic activity that uses mercury during the amalgamation process to obtain gold. The waste generated in the form of soil tailings and pan-pond water contains mercury and is located close to community boreholes. The proximity may predispose groundwater to mercury contamination. Boreholes are one of the main water sources in Migori County. Ingestion is one of the ways mercury can get into the human body. This study was conducted to establish mercury concentration in groundwater from boreholes, soil tailings and pan-pond water located near five mine sites in Migori County during dry and wet seasons in comparison with drinking water standards required by KEBS and NEMA effluents discharge standards. The five mines were: -Masara, Osiri Matanda, Macalder, Kitere and Kehancha. The study used a cross-sectional-analytical study design and focused on boreholes found within a distance of 6 km from each of the five mines. Fifteen boreholes were proportionately sampled to obtain groundwater samples. 20 pan-pond water and soil tailing samples were collected in both dry and wet seasons as per the respective sampling protocols applied. Inductively Coupled Plasma –Mass Spectroscopy (7900 ICP-MS) was used to measure mercury levels. A paired t-test was used to compare the means of the levels of mercury in groundwater obtained within the two seasons. The study established that during the dry season, all of the boreholes had groundwater mercury levels higher than the recommended limit by KEBS of 0.001 mg/L. There was a decrease in the levels of mercury in groundwater as distances from the mine increased. However, during the wet season, all of the boreholes had mercury levels below the limit of detection. The study established a significant difference in the levels of mercury in groundwater between wet and dry seasons at a 95% confidence level. Mercury levels in soil tailings and pan-pond water were above the NEMA effluents discharge standards of 0.05 mg/kg and 0.05 mg/L, respectively, in the dry season. During the wet season, all pan-pond water achieved the recommended mercury level of NEMA effluent discharge limits, while the soil tailings had mercury levels above the recommended limit. This study recommends that there is a need to implement mine waste remediation. Communities near the mines continuously conduct groundwater heavy metal analysis during the dry season to protect their health
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References
Abdul-Wahab, S., & Marikar, F. (2012). The environmental impact of gold mines: pollution by heavy metals. Open engineering, 2(2), 304-313.
Barcelona, M. J. (1985). A practical guide for ground-water sampling (Vol. 600, No. 2-104). Robert S. Kerr Environmental Research Laboratory, Office of Research and Development, US Environmental Protection Agency.
CEJAD Kenya. (2017). Mercury Pollution Costs Billions in Lost Earning Potential in Kenya CEJAD.http://cejadkenya.org/mercury-pollution-costs-billions-in-lostearningpotential-in-kenya/
Croghan, C. A. P. P. E., & Egeghy, P. P. (2003). Methods of dealing with values below the limit of detection using SAS. Southern SAS User Group, 22, 24.
Cossa, H., Dietler, D., Macete, E., Munguambe, K., Winkler, M. S., & Fink, G. (2022). Assessing the effects of mining projects on child health in sub-Saharan Africa: a multi country analysis. Globalisation and health, 18(1), 1-16.
Dorleku, M. K., Nukpezah, D., & Carboo, D. (2018). Effects of small-scale gold mining on heavy metal levels in groundwater in the Lower Pra Basin of Ghana. Applied Water Science, 8(5), 1-11.
El-Salam, M. M. A., & Abu-Zuid, G. I. (2015). Impact of landfill leachate on the groundwater quality: A case study in Egypt. Journal of advanced research, 6(4), 579-586.
Esdaile, L. J., & Chalker, J. M. (2018). The mercury problem in artisanal and small‐scale gold mining. Chemistry–A European Journal, 24(27), 6905-6916.
Githiria, J., Ngetich, V., Mengich, H., & Onifade, M. (2020). Environmental and Health Effects in Artisanal and Small-Scale Gold Mining in Kenya. African Journal of Mining, Entrepreneurship and Natural Resource Management, 2(1), 78-83.
Hathhorn, W. E., & Yonge, D. R. (1995). The assessment of groundwater pollution potential resulting from stormwater. Infiltration Best Management Research Report, US FHWA.
Hu, L., Zhang, M., Yang, Z., Fan, Y., Li, J., Wang, H., & Lubale, C. (2020). Estimating dewatering in an underground mine by using a 3D finite element model. Plos one, 15(10), e0239682.
Agilent. (2022). ICP mass spec, Inductively Coupled Plasma – Mass Spectrometry. https://www.agilent.com/en/product/atomicspectroscop/inductively-coupledplasma-mass-spectrometry-icp-ms/icp-msinstruments/7900-icpms.
IPEN. (2018). Mercury rising: Gold mining takes a toxic toll on Kenyan women. https://ipen.org/news/mercury-rising-gold-mining-takes-toxictoll-kenyan-women
Kar, D., Sur, P., Mandai, S. K., Saha, T., & Kole, R. K. (2008). Assessment of heavy metal pollution in surface water. International Journal of Environmental Science & Technology, 5(1), 119-124.
Migori-Kihancha Regional Master Plan (1975) Wageningen University & Research eDepot. Available at: https://edepot.wur.nl/ (Accessed: 13 December 2022).
MoALFC. 2021. Climate Risk profile for Migori County. Kenya County Climate Risk Profile Series. The Ministry of Agriculture, Livestock, Fisheries and Cooperatives (MoALFC), Nairobi Kenya
Kingston, H. M., & Walter, P. J. (1998). The art and science of microwave sample preparations for trace and ultratrace elemental analysis. Inductively coupled plasma mass spectrometry, 33-81.
Loizidou, M., & Kapetanios, E. G. (1993). Effect of leachate from landfills on underground water quality. Science of the Total Environment, 128(1), 69-81.
Lusilao-Makiese, J. G., Tessier, E., Amouroux, D., Tutu, H., Chimuka, L., Weiersbye, I., & Cukrowska, E. M. (2014). Seasonal distribution and speciation of mercury in a gold mining area, north-west province, South Africa. Toxicological & Environmental Chemistry, 96(3), 387-402.
Macháček, J. (2019). Typology of environmental impacts of artisanal and small-scale mining in African Great Lakes Region. Sustainability, 11(11), 3027.
Mantey, J., Nyarko, K. B., Owusu-Nimo, F., Awua, K. A., Bempah, C. K., Amankwah, R. K., ... & Appiah-Effah, E. (2016). Mercury contamination of soil and water media from different illegal artisanal small-scale gold mining operations (galamsey). Heliyon, 6(6), e04312.
Michael, A., & Demian, S. P. (2022). Hydraulic Head and the Direction of Groundwater Flow EARTH 111: Water: Science and Society. https://www.e-education.psu.edu/earth111/node/932.
Migori County Government. (2018). Migori County Profile. Retrieved from http://migori.go.ke/index.php/about-migori-county/county government/migori-countyprofile
Mugenda, A. G., & Mugenda, A. G. (2008). Social science research: Theory and principles. Nairobi: Applied.
Obiri, S. (2007). Determination of heavy metals in water from boreholes in Dumasi in the Wassa West District of western region of Republic of Ghana. Environmental monitoring and assessment, 130, 455-463.
Ochiba, K. N. (2020). Assessment of levels of selected heavy metals in borehole water in Ongata Rongai, Kajiado County, Kenya
Ogola, J. S., Mitullah, W. V., & Omulo, M. A. (2002). Impact of gold mining on the environment and human health: a case study in the Migori gold belt, Kenya. Environmental geochemistry and health, 24(2), 141-157.
Palumbo-Roe, B., Olaka, L., Bell, R., Mitchell, C., Bide, T., Odiwuor, C., & Barlow, T. (2021). Reconnaissance study of groundwater quality in the artisanal gold mining districts of Migori County, Kenya.
Responsiblemines,O.(2018). Understanding the Economic Contribution of Small-Scale Mining in East Africa. https://www.responsiblemines.org/en/2018/04/understanding-the-economic-contribution-of-small-scale-mining-in-eastafrica/#:~:text=ASM%20produces%20a%20crucial%20source,spent%20within%20te%20local%20economy.
Singh, G., & Kamal, R. K. (2015). Assessment of groundwater quality in the mining areas of Goa, India. Indian Journal of Science and Technology, 8(6), 588-595.
Solan, T. D., & Lindow, S. W. (2014). Mercury exposure in pregnancy: a review. Journal of perinatal medicine, 42(6), 725-729.
Udofia, U. U., Joseph, A. P., & Okoro, F. T. (2019). Assessment of the pollution threat of boreholes located around an abandoned dumpsite in Uyo Metropolis, Akwa Ibom State, Nigeria. J. Sci. Res. Rep, 21, 1-9.
United Nations Environment Programme (UNEP). 2013. Mercury – Time to Act. http://www.unep.org/hazardoussubstances/Mercury/Informationmaterials/Repotsand Publications/tabid/3593/Default.aspx.
United Nations Environment Programme (UNEP). (2002) Global Mercury Assessment. UNEP chemical mercury programme. www.chem.unep.ch/mercury/report/final.
United Nationals Environment Programme (UNEP). (2012). Reducing Mercury Use in Artisanal and Small-Scale Gold Mining: A Practical Guide. http://www.unep.org/hazardoussubstances/Portals/9/Mercury/Documents/ASGM/Techdoc/UNEP%20Tech%20Doc%20APRIL%202012_120608b_web.pdf
Veiga, M. M., Baker, R. F., Fried, M. B., & Withers, D. (2004). Protocols for environmental and health assessment of mercury released by artisanal and small-scale gold miners. United Nations Publications.
WASREB. (2008). Drinking Water Quality and Effluent Monitoring Guideline. Wasreb.go.ke. https://wasreb.go.ke/downloads/Drinking%20Water%20Guidelines%20gwqem_Edited.pdf.
Yabe, J., Ishizuka, M., & Umemura, T. (2010). Current levels of heavy metal pollution in Africa. Journal of Veterinary Medical Science, 72(10), 1257-1263.
Copyright (c) 2023 George Zachary Ochieng Omondi, Jackim Nyamari, PhD, Judy Mugo, PhD
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