Distribution of Metal Contaminants in Azare Groundwater System
Distribution of Metal Contaminants in Azare Groundwater System.
ABSTRACT
The distribution of metal contaminants in the Azare groundwater system was investigated in this study. Concentrations of total and soluble forms of K, Ca, Mg, Cu, Zn, Mn, Pb, and Cd were determined in randomly selected twenty boreholes and twenty hand-dug wells within Azare town using flame Atomic Absorption Spectroscopy.
Findings revealed that, the mean total concentrations of K, Ca, Mg, Cu, Zn, Mn, Pb and Cd in borehole waters were 0.3233±0.2455mg/L, 0.5433±0.1762mg/L, 0.3178±0.1641mg/L, 0.2386± 0.1361mg/L, 0.3260 ± 0.3187mg/L, 0.1879± 0.1082mg/L, 0.1234 ±0.1480mg/L, and 0.0049 ± 0.0037mg/L respectively
while the mean total concentrations of K, Ca, Mg, Cu, Zn, Mn, Pb and Cd in well waters were 0.8790±90.6823mg/L,1.1923±1.1337mg/L,0.9543±1.0186mg/L,0.0953±0.1083mg/L,0.1890±0.0791mg/L, 0.1645±0.1238mg/L,0.0965± 0.0491mg/L, and 0.0041±0.0034mg/L respectively.
It was also discovered that in all the samples investigated, concentrations of Cu and Zn were found below the Maximum Contaminant Levels (MCLs) for these metals in drinking water (MCL for Cu = 1.3mg/L and MCL for Zn = 5.0mg/L) while the total concentration of Pb exceeded the MCL for this metal in drinking water (MCL for Pb = 0.015mg/L).
Concentrations of total Mn exceeded the MCL for this metal (0.05mg/L) in all the borehole waters investigated but it only exceeded the MCL for this metal in 95% of the well waters investigated.
The concentrations of total Cd were found to exceed the MCL for this metal (0.005mg/L) in 45% of the borehole waters and 35% of the well waters investigated in this study. Apart from K and Cu, no significant differences were found between the mean concentrations of total metal contaminants in boreholes and hand-dug wells investigated.
Findings also revealed that on the average, K, Ca, Mg, Zn and Mn exist predominantly in the soluble phase while Cu, Pb and Cd exist predominantly in the particulate phase.
The average proportions of the soluble forms of these metals in boreholes were 84.9% for K, 80.5% for Ca, 88.6% for Mg, 22.2% for Cu, 67.2% for Zn, 56.8% for Mn,
39.9% for Pb, and 17.5% for Cd while the average proportions of the soluble forms of these metals in hand-dug wells were 93.1% for K, 87.6% for Ca, 91.8% for Mg, 25.5% for Cu, 69.3% for Zn, 76.5% for Mn, 44.5% for Pb and 42.5% for Cd.
Implications of the findings were discussed and some useful suggestions are given.
INTRODUCTION
Background of the Study
Azare is the headquarter of Katagum local government area in the Bauchi state of Nigeria. It has a population of over one hundred and fifty thousand according to the 1991 population census (Shehu, 2000).
Azare is often regarded as the second most developed city in the state, in terms of the provision of social amenities.
However, majority of the people in Azare, according to Alabi (2005), still depend on groundwater (bore-holes and wells) for drinking and other domestic purposes.
It is an age-long belief among the people that groundwater is pure and safe for drinking but recent discoveries have shown that like surface water, groundwater is also vulnerable to contamination from a variety of sources (Texas Environmental Profiles, 2003).
According to Ademoroti (1996), groundwater contamination may be from seepages from agricultural activities, septic systems, and mining activities, and even from geological origin. Assessing the dangers from metallic contaminants to human healths involves concerns that are different from those associated with organic chemicals.
Organic chemicals are generally broken down over time in the environment but metals are not and can easily be accumulated and concentrated in living systems (Chemical and Engineering News, 2002).
REFERENCES
Ademoroti, C.M.A (1996): Environmental Chemistry and Toxicology. Foludex Press Ltd. Ibadan
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