Changes in Surface Water Physico-Chemical Parameters following the Dredging of Otamiri and Nworie Rivers, Imo State of Nigeria

摘要

In an attempt to study the environmental impact of dredging on water quality, surface water quality parameters were monitored from June 2008 to October 2010. Samples were collected before and after dredging. Collected samples were analysed from five stations within the study area. The water physico-chemistry prior to dredging was consistent with that of researches done previously in that area. As a result of dredging however, the pH of the dredged canal was decreased from a mean value of 6.5 to 6.04, similarly dissolved oxygen(DO) decreased from 13.88mg/l to 8.66mg/l, while TSS, BOD_(5)and COD_(5) decreased slightly after dredging. Acidity and alkalinity values did not show significant changes. Results of the ten-months post dredging monitoring of the Rivers water revealed that the water quality improved slightly during this period. The pH, DO, and TSS appreciated, while BOD_(5), COD_(5) turbidity, Total hardness, Acidity, Alkalinity, and Electrical conductivity depreciated to values close to pre-dredging concentration levels. We therefore concluded that the impact of dredging on the water quality is localised and short term.