Determination of selected heavy metals in inland fresh water of lower River Niger drainage in North Central Nigeria

Abstract

The concentrations of some ferruginous ore associated heavy metals were determined in freshwater from River Niger. Water samples were collected from both upstream and downstream along the mainstream drainage channel, traversing past the steel production industry Ajaokuta between 2003 and 2005. The water samples were digested according to standard methods and tested for Cadmium (Cd), Manganese (Mn), Chromium (Cr), Nickel (Ni), Cupper (Cu), Zinc (Zn) and Lead (Pb) using Unicam 969 atomic absorption spectrophotometer. The mean concentrations (mg/L) of heavy metals were: Mn, 3.85 ± 0.93; Zn, 2.72 ± 0.57; Cu, 2.17 ± 0.73; Cr, 2.08 ± 1.27; Ni, 0.78 ± 0.12; Cd, 0.05 ± 0.02; Pb, 0.03 ± 0.02. The concentration of Mn, 1.74 to 8.37 mg/L; Cu, 0.58 to 4.50 mg/L; Cd, 0.02 to 0.13 mg/L were variable and inundating. The variations in heavy metal levels between sampling stations were not significant (P > 0.05) with relative standard deviation from 2% for Cd and Pb to 12.7% for Cr. The order of dispersion (2 to 14%) showed that the measured metals are nearly homogenously distributed in the water with Cr, Mn, Cu and Zn having the highest concentration variations in the water samples. The concentrations of the evaluated heavy metals were within the guideline levels for freshwaters, and did not appear to have significant negative impact on the water quality.

Studies on contamination of surface waters of river Benue with trace elements at Makurdi, Benue State, Nigeria

“…This may be that the season is contributing to the concentration of Pb in River Benue while the station is not. The results of this study agrees with the finding of other studies that reported Pb beyond the permitted limits (Hong et al, 2014;Wangboje and Ekundayo, 2013;Olatunji and Osibanjo, 2012;Aderinola et al, 2009). The result of the seasonal variation of the Pb concentration in the water samples showed that the concentration of Pb during the dry season was higher compared to the rainy season.…”

“…This may be due to the fact that during the dry season, the quantity of the water is reduced and the concentration therefore increased. This result is similar to the findings of Olatunji and Osibanjo (2012) that reported higher values of Pb during the dry season in lower River Niger drainage in North central Nigeria. Across the stations, station V had the highest Pb concentration while station VI the lowest during the study period.…”

“…Studies have shown that drinking water with more 0.02 mg/L of Ni may be carcinogenic (WHO, 2004). The findings of this study conform to that of other studies that reported Ni in surface waters beyond the WHO recommended value (Wangboje and Ekundayo, 2013;Tabinda et al, 2013;Olatunji and Osibanjo, 2012;Yahaya et al, 2012, Aderinola et al, 2009Enuneku et al, 2013). However, the result of Ayas et al (2007) differs significantly from this study.…”

“…Nevertheless the result of other studies differs significantly with the findings of this study that reported the concentration of Cu in surface waters beyond the recommended concentrations (Ekpo et al, 2013;Olatunji and Osibanjo, 2012;Hong et al, 2014). A perusal at the seasonal variation in the level of Copper in River Benue during the study period showed that the concentration of Copper during the dry season was higher as compared to the rainy season.…”

“…This is because the season is contributing to the increase and decrease in the concentration of Ni in River Benue at Makurdi during the period of the study. The high concentration of Ni during the dry season as compared to rainy seasons is similar to the findings of others studies (Olatunji and Osibanjo, 2012). However, the result of this study differs significantly from the findings of other studies that reported higher concentration of Ni in rainy season as compared to the dry season (Tabinda et al, 2013).…”