Roof Runoff Water as Source of Pollution: A Case Study of Some Selected Roofs in Orlu Metropolis, Imo State, Nigeria

Abstract

Samples collected from different runoffs; AR, GMR, TR, ASR, and DR for aluminum roof, galvanized metal roof, thatch roof, asbestos roof and ambient rainfall respectively were analyzed for pH, conductivity, turbidity, TDS, TSS, NO3-, PO43-, Cd, Cu, Fe, Zn and Pb. The result indicates that the mean concentration of the parameters analyzed ranged from 5.8± 0.39 –7.10±0.70, 22.25±11.70-79.99± 3.40μScm-1, 1.47±0.43 - 46.53±1.60mg/l, 11.90±0.93 - 59.83±1.62NTU,15.53±0.70 - 204.53±5.08mg/l, 0.93±0.06 - 2.55±0.13 mg/l, 1.33±0.22 - 7.30±0.57mg/l respectively for pH, conductivity, TDS, turbidity, TSS, PO43- and NO3-, and the levels of the heavy metals (in mg/l); Cd, Cu, Fe, Zn and Pb ranged from 0.0023±0.001– 0.0521±0.004, 0.052±0.01–0.2483±0.02, 0.0348±0.01–1.1120±0.07, 0.0161±0.01-0.8093±0.02 and 0.0106±0.01-0.0499±0.002 respectively. Ranking of the heavy metal in roof runoff is in the order; Fe>Zn>Cu>Cd>Pb. The result compared with WHO standard showed elevated level of the parameters analyzed with Cd and Pb exceeding the limit. Though the result of this study showed some variability which is an indication of the type of roofing material; air quality of the environment and industrial activity going on in the area. It could be deduced from the result that roof runoff may be a non point source of environmental pollution owning to the release of heavy metals and other pollutants into the environment, and increased concentration of some of the pollutants as reported by this study suggests that roof runoff water could impact negatively to the environment and if consumed without being treated may be injurious to human health.