Abstract

Contaminations from natural and anthropogenic activities have really affected the rainwater quality through the effect of high industrial activities and the leaching from roof type components. This led to this study which determined the physico-chemical properties, coliform level, heavy metals of the rainwater/digested roof types. Rainwater was harvested from non-roof (control) and from various roof types in Okpanam Road, Asaba and Warri Refinery Depot, Uvwie, Delta State, Nigeria between April-July, 2018. Heavy metals were analyzed using the Flame Atomic Absorption Spectrophotometer and some other parameters were assessed using standard methods. Descriptive and two-way ANOVA statistical analysis was used for the obtained values. Results were compared with the water quality standards of WHO, USEPA and NSDWQ. The Water Quality Index (WQI) of the rainwater samples was evaluated. The values obtained gave mean values ranging from 6.40-8.80 for pH, E.coli (not detected), heavy metals (mg/L) gave 0.00-0.11 for Fe, Pb(0.00-0.79), Cr (0.00-0.06), Zn (0.01-0.10), Al (0.00-0.81) and metal concentrations (mg/kg) of digested roofs gave 0.00-31.84 (Pb), 0.00-43.45 (Al), 39.22-63.78 (Fe), 0.59-7.04 (Zn) and 1.87-6.20 (Cr). The results showed that all the parameters analyzed were below, within and above the water quality standard and the values were significantly different at (P<0.05). The WQI ranged from 0.05-5,975.77 which rated excellent to unfit for drinking and other domestic purposes. It was concluded that harvested rainwater should be treated before drinking and some helpful recommendations were proposed in this study.

Keywords:Harvested rainwater; Leaching; Toxicity; Atmospheric pollution; Water quality index