Physicochemical Quality of Water and Health Risks Associated with the Consumption of the Extant African Lung Fish (<i>Protopterus annectens</i>) from Nyabarongo and Nyabugogo Rivers, Rwanda

Abstract

Water is an indispensable natural resource that is often prodigiously threatened by anthropomorphic activities. This study evaluated the physicochemical properties of water and selected heavy metals in edible muscles of a piscivorous fish (Protopterus annectens) from Nyabarongo and Nyabugogo rivers of Rwanda. Edibility health risk was evaluated using the target hazard quotient method. Water samples were taken in triplicate from Ruliba station and Kirinda bridge on Nyabarongo river and Giticyinyoni on Nyabugogo river. Fish samples were obtained from the sampling stations on Nyabarongo river. All samples were analyzed following standard methods and analytical results indicated that the average temperature, pH, total dissolved solids and electrolytic conductivity of water from the rivers were within WHO acceptable limits. The statistical mean concentrations of the ionic components of the water samples were 1.61 &amp;plusmn; 0.03, 0.53 &amp;plusmn; 0.002, 0.24 &amp;plusmn; 0.02 and 0.051 &amp;plusmn; 0.01 mg/L for Fe, Mn, Cu and Pb respectively at Ruliba station and 0.63 &amp;plusmn; 0.02, 0.02 &amp;plusmn; 0.002, 0.09 &amp;plusmn; 0.01, 0.06 &amp;plusmn; 0.002 and 0.75 &amp;plusmn; 0.02 mg/L for Fe, Mn, Zn, Cr and Pb respectively at Kirinda bridge. Water from Giticyinyoni had 1.57 &amp;plusmn; 0.02, 0.49 &amp;plusmn; 0.03, 0.29 &amp;plusmn; 0.058, 0.43 &amp;plusmn; 0.058, 0.15 &amp;plusmn; 0.00 and 0.59 &amp;plusmn; 0.058 mg/L of Fe, Mn, Cu, Zn, Cr and Pb respectively. Zinc, Cu, Cr and Cd were below detection limits in samples from Ruliba station and Kirinda bridge (Nyabarongo river). Edible muscles of P. annectens from Nyabarongo river contained 272.8 &amp;plusmn; 0.36, 292.2 &amp;plusmn; 0.25, 8.8 &amp;plusmn; 0.36, 135.2 &amp;plusmn; 0.15, 148.0 &amp;plusmn; 0.21 and 432. 0 &amp;plusmn; 0.50 mgkg-1 for Fe, Mn, Cu, Zn, Cr and Pb at Ruliba station and 336.0 &amp;plusmn; 0.70, 302.6 &amp;plusmn; 1.22, 6.4 &amp;plusmn; 0.26, 44.7 &amp;plusmn; 0.20, 138.2 &amp;plusmn; 0.17 and 302.4 &amp;plusmn; 1.50 mgkg-1 for Fe, Mn, Cu, Zn, Cr and Pb respectively at Kirinda bridge. Health risk assessment indicated that consumption of the edible muscles of P. annectens may lead to deleterious health effects as reflected by values of target hazard quotients being greater than one. Therefore, the Rwandese government should lay strategies to reduce pollution of the rivers. Further research should evaluate the heavy metal content of metabolically active organs of P. annectens from Nyabarongo river as well as the microbiological profile of water from the rivers.

Physicochemical Quality of Water from Chuho Springs, Kisoro District, Uganda

“…Slightly acidic pH of Ugandan springs were previously thought to be induced by carbon dioxide saturation in the ground water [15,20,40]. It is important to note that even within the acceptable pH range, slightly high pH causes water to have a slippery feel whereas slightly low pH may cause water to have a bitter or metallic taste [15,30,41].…”

“…Further, TDS showed a significant positive correlation with temperature (r = 0.091, p = 0.000). Generally, high TDS affects the aesthetic quality of water, interferes with washing operations and can be corrosive to plumbing fixtures [41].…”

Effects of sewage sludge biosolid amendments on the potential of maize (Zea mays L.) in phytoremediation of trace metals in chromated copper arsenate contaminated soils

“…The solutions were cooled and subsequently filtered into 50 ml volumetric flasks and made to the mark with distilled water [26]. A 20% blank prepared using 15 ml of 63% nitric acid (Sigma Aldrich) and 5 ml of 98% and the absorbances were used to compute the concentrations of the metals from the standard curves [27]. The results in mg/L from the instrument were converted to the standard unit (mg/kg) for easy comparison with the set international compliance guidelines [28,29].…”