Mercury Levels in Groundwater near Artisanal Small-Scale Gold Mines in Migori County, Kenya
Loading...
Date
2023-10
Authors
Omondi, George Zachary Ochieng
Nyamari, Jackim
Mugo, Judy
Journal Title
Journal ISSN
Volume Title
Publisher
EANSO
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.
Description
Article
Keywords
Artisanal and SmallScale Gold Mining, Mercury, Inductively Coupled Plasma Mass Spectrometry, Limit of Detection, National Environment Management Authority, Kenya Bureau of Standards
Citation
Omondi, G. Z. O., Nyamari, J. & Mugo, J. (2023). Mercury Levels in Groundwater near Artisanal Small-Scale Gold Mines in Migori County, Kenya. East African Journal of Environment and Natural Resources, 6(1), 421-431. https://doi.org/10.37284/eajenr.6.1.1543.