Abstract:
The study was undertaken basically to assess the status of drinking water quality in relation with
traditional gold mining activities at the gold mining areas of Bero Woreda, Bench Maji Zone, South West
Ethiopia. Prior to sampling deliberate observation was made & site specific data were taken from each
site. A total of 6 water samples (4 well water samples & 2 stream water samples (for reference)) were
collected in February, 2011 from 3 gold mining kebeles (Sholla, Gabissa & Seyali).
Field measurements of water quality indicator parameters: Temperature (24–28 0C), pH (7.02–8.1),
Electrical conductivity (927–1726 µS/cm) & Turbidity (28–230 NTU) were measured & TDS (593–1105
mg/l) was calculated from the measured EC value of the samples.
All the samples were analyzed for the toxic heavy metals: As, Hg, Cd, Pb & Cu following the
recommended standard procedures. The heavy metals (As & Hg) were analyzed using hydride AAS
method & the heavy metals (Cd, Pb & Cu) & major cation (Ca2+ & Mg2+) were analyzed using Flame
AAS method. From the analyses the following analytical results in (mg/l): As (0.00091–0.0031), Hg
(0.00011– 0.00199), Cu (0.159) only at one well sample site, Pb & Cd below the detection limit (0.0001
mg/l) of the instrument, calcium (114.4 – 292.2) & magnesium (99.2–191.5) were obtained.
The major ions in mg/l: sulphate (1.02–80), chloride (7.4–88.3) & bicarbonate (314.5–594.5) were
obtained. As, Hg, SO4
2-, Cl-
, pH & turbidity were found higher in stream water samples & also As, Hg,
SO4
-2, Cl-
, pH , HCO3
-
, EC & turbidity were found higher in downstream than upstream water samples.
The physicochemical parameters mercury, temperature, turbidity, electrical conductivity (EC), bicarbonate
& TDS were found in 66.7%, 100%, 100%, 100%, 50% & 100% of the water samples in the study area
respectively. These parameters were also found in 50%, 100%, 100%, 100%, 75% & 100% of the well
water samples respectively higher than the WHO (1993), EU (1998) & ES (2001) recommended
maximum desirable limits set for drinking water.
