Browsing by Author "Udensi, Justina U."

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    Studies on the recovery potentials of a disturbed aquatic ecosystem: Focus on pre-and post-dredging analysis of Nworie River, Owerri, Imo State, Nigeria
    (U. P, 2014-06) Udensi, Justina U.; Iwuala, Moses O. E.; Nwigwe, Harriet C.; Onyedineke, Nkechi E.; Okereke, Joseph N.; Mgbemena, Ifeyinwa C.
    A study was done to monitor the recovery potential of Nworie river system, in Imo State, Ni- geria from July 2010 to January 2012. Water samples were collected from 5 Stations prior to, during and after dredging. Station 1 was the dredging point, Stations 2 and 3 were 250m and 500m upstream of the point, while Stations 4 and 5 were 250m and 500m downstream of the dredging point respectively. The physicochemical parameters of the water before dredging were assessed to be within acceptable limits of established water standards; pH 6.5-7.8, Tem- perature 27.6-29.9 °C, Conductivity 34-196us/cm, Turbidity 0-76NTU, TDS 22.1-127.4 mg/l, TSS 9-51mg/l, Nitrate 1.2-33.6mg/l, Phosphate 0.2-3.7mg/1, Sulphate 0-33mg/l, DO 4.3- 9.4mg/l and BOD5 9.5- 10.9mg/l. During the dredging, the water physicochemistry changed noticeably with indices outside the permissible limits of the standards. The pH values de- creased drastically to 4.6, DO to 1.3mg/l, Nitrate to 1.2mg/l, temperature increased to 30.2°C, Turbidity 620NTU, TSS 349mg/l, Conductivity 498 μs/cm, TDS 298.8 mg/l, BOD5 19.1mg/l, Sulphate 33mg/l and Phosphate 0.92mg/l. Three months after the dredging, the values for the parameters returned to their pre-dredging concentrations. However, during the rainy season, as the leachates and silts from the spoils were washed into the river, the recovery of the river sys- tem was prolonged to about 9 months. This implies that the effects of dredging on the river are short term, but improper disposal of dredge spoils compounded the impacts.