SOME MICROBIAL AND HEAVY METAL POLLUTION OF RIVER KADUNA FROM KADUNA SOUTH WATERWORKS TO 100M DOWNSTREAM OF RIVERS ROMI-KADUNA CONFLUENCE
SOME MICROBIAL AND HEAVY METAL POLLUTION OF RIVER KADUNA FROM KADUNA SOUTH WATERWORKS TO 100M DOWNSTREAM OF RIVERS ROMI-KADUNA CONFLUENCE
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Date
2018-08
Authors
OKAFO, Cordelia Ngozi
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Abstract
In Nigeria, waste discharges from domestic, municipal, trade, industrial and agricultural set-ups contain various pollutants including heavy metals and microbes. The river water is also contaminated with fecal samples from humans and animals introducing enteric microbes including E. coli O157:H7 and Cryptosporidium oocysts. These waste discharges are conveyed (mostly untreated) through drains, water-ways and soils into inland water-bodies. The water is used for irrigation of vegetable crops and, fish, being relatively situated at the top of the aquatic food chain, can accumulate heavy metals from water, food and sediments. The pollution of River Kaduna from Kaduna South Waterworks to 100 meter downstream of River Romi-Kaduna confluence was studied. The study investigated the levels of some heavy metals including chromium (Cr), cadmium (Cd), lead (Pb) and zinc (Zn) in the water and fish samples obtained from the river, and in cabbage, cucumber, jute, lettuce and amaranthus cultivated on the banks of the river. The microbial quality of the river water including Escherichia coli O157:H7 and Cryptosporidium was also studied. Two hundred and eight (208) water samples, 56 vegetable samples and 57 fish samples were used for the study. Determination of the heavy metals in the different samples was carried outby means of Atomic Absorption Spectrophotometer (Varian, model AA240FS) after digestion. Cryptosporidium oocysts were detected by the flocculation method and microscopy. Escherichia coli was isolated from water samples using the Tryptic Soya Broth (TSB) enrichment and high temperature (44.5°C ) incubation, followed by plating for isolation on Eosine Methylene Blue (EMB) agar. Biochemically confirmed E. coli isolates were screened on Sorbitol MacConkey agar and presumptive E. coli O157:H7 further confirmed by testing for agglutination with E. coli O157:H7 antisera. The levels of the
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heavy metals (Cr, Cd, Pb and Zn) in the river water were within the limits for discharge of effluents into surface water but Cd and Cr were above the 0.01mg/l and 0.1mg/l Food and Agriculture Organization (FAO) limit for irrigation water. All the fish samples tested contained the metals in varying concentrations. The levels of the metals in the fish species were however, within the permissible limits set by FAO and US FDA. Vegetable samples obtained from the banks of the river were also evaluated for the same elemental toxicants. The concentrations of Cd, Cr and Zn in the vegetables were within the FAO/WHO recommended safe limits of 0.2 mg/kg, 2.3 mg/kg and 20 mg/kg respectively. However, the mean level of Pb in cabbage (0.70 mg/kg), cucumber (0.77mg/kg) and jute (0.43mg/kg) exceeded the 0.3mg/kg permissible limits. Cryptosporidium oocysts were detected at some locations along the river. Similarly, Escherichia coli O157:H7 was found in some of the water samples. The E. coli O157:H7 isolated from the water samples exhibited high resistance to amoxicillin, sulphamethoxazole/trimethroprim and doxycycline. The presence of some antibiotic resistance genes (TEM, SHV, CTX-M, dfrII, Sul and TET) was established among some of the E. coli O157:H7 isolates. All the E. coli O157:H7 isolates expressed the virulence gene shiga toxin 1 while 66.7% of them expressed the gene shiga toxin 2. The study has established that the stretch of the River Kaduna studied was polluted. It is recommended that an integrated wastes treatment technology employing Best Management Practices (BMP) should be adopted by the industries within the river vicinity and there is need for epidemiological studies on the immediate communities that have direct or indirect contact with the river water in order to properly assess the health hazards of the pollutants
Description
A THESIS SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES AHMADU BELLO UNIVERSITY, ZARIA, NIGERIA IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF DOCTOR OF PHILOSOPHY (Ph.D) IN MICROBIOLOGY DEPARTMENT OF MICROBIOLOGY, FACULTY OF LIFE SCIENCES, AHMADU BELLO UNIVERSITY, ZARIA, NIGERIA
Keywords
SOME MICROBIAL,, HEAVY METAL POLLUTION,, RIVER KADUNA,, KADUNA SOUTH,, WATERWORKS,, 100M DOWNSTREAM,, RIVERS,, ROMI-KADUNA,, CONFLUENCE,