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Spatial and Temporal Variation of Escherichia Coli in Water and Soil with Relation to Water Parameters at the Estuary of Karnafuly River, Bangladesh

Md. Wahidul Alam
Institute of Marine Sciences and Fisheries, University of Chittagong, Chittagong-4331, Bangladesh.

Mohammad Zafar
Institute of Marine Sciences and Fisheries, University of Chittagong, Chittagong-4331, Bangladesh.

Abstract/ Executive Summary:

This study examined the concentrations of Escherichia coli in soil and water samples, and some physicochemical properties of water collected from the Karnafuly River estuary, Bangladesh during March-June 2012. Among the water parameters, temperature was in the range 26.5 to 32°C, salinity varied between 0 and 5 ppt, pH values ranged from 7.5 to 7.9 and dissolved oxygen (DO) was recorded at concentrations of 2.28 to 2.91 mg/l. The average total E. coli were 26 cells/ml in water, but the sediment contained 96.42 cells/g of E. coli. The population of E. coli was always higher in sediment than those that occurred in water among all sampling stations. The growth of E. coli were positively correlated (P < 0.01) with water temperature and negatively correlated with salinity, pH and DO. The data on water quality parameters and occurrence of E. coli indicated that water of the Karnafuly estuary is polluted and unhygienic for drinking, even impossible to use for washing purposes without any treatment.

Keywords: Karnafuly, Escherichia coli, Physicochemical, Estuary.

Location: Chittagong District

Start Date: 00-03-2012

End Date: 00-06-2012

Program Area: Conservation and Biodiversity

Commodity: Aquatic animal

Objectives:

To determine the concentrations of E. coli in water and soil of Karnafuly River estuary, including their relationship with some water parameters.

Methodology:

Description of the study area: The Karnafuly is the principal river of Chittagong District of Bangladesh. It originates in the Lushai Hills of Mizoram (India), flows through Rangamati and the port city of Chittagong and discharges into the Bay of Bengal near Patenga. The river is flashy and its length is about 131 km. Geographically, this estuary is located between latitude 22°53’ N and longitude 92°27’ E and enters the districts of Chittagong from the north eastern side. It travels about 121 miles in zigzag ways to the west and south west side and finally falls on the Bay of Bengal at latitude 22°12’ N and longitude 91°47’ E at near Patenga, Chittagong. The average channel depth of the basin at the river estuary is 8 m, although the depth varies greatly in its upstream portion for strong current and siltation. Geologically, the entire catchment consists of a substratum of tertiary rocks covered with alluvial deposits. The overlying deposits show that it consists of successive layers of mud and sand. Hydrological parameters that is temperature, salinity, pH, D.O etc. fluctuate seasonally. Three sampling stations were selected for the present investigation with the basis of different types of pollution. The first sampling station (St-1) located near Chaktai canal (most polluted canal of Bangladesh), receives heavy discharges from different domestic and industrial sources to the estuary. The second sampling station (St-2) is located at the middle portion of the River, where small city canal falls into the river and carry industrial and city wastes. The third sampling station (St- 3) is located at the mouth of the estuary and receives discharges composed of different kinds of city wastes through a canal which ultimately falls into the estuary. Data collection and analysis: This work was carried out from March to June 2012. Water and soil samples were collected from three stations of the Karnafuly River estuary during this study period. In situ measurement of water temperature was measured with a centigrade thermometer while water pH and salinity were measured by pen pH meter and refractometer respectively. Dissolved Oxygen (DO) concentration was measured in the laboratory by following standard method. Collected water and soil samples were preserved and microbial analysis was conducted in the laboratory to identify E. coli in water and soil of the Karnafuly Estuary. E. coli of water and soil were identified by standard plate count (SPC) techniques. SPC was conducted by making serial dilution, plating and total plate count by pour plate techniques. In case of water, 1 ml of water sample was transferred with a sterile pipette to a sterile screw capped vial containing 9 ml of distilled water and the vial was shaken thoroughly. The sample was made to give 1:10 or 10^-1. In case of soil, 1 g of soil sample was weighted by weight meter and then transferred to a sterile screw capped vial containing 9 ml of distilled water and then the vial was shaken thoroughly. The sample was made to give 1:10 or 10^-1. Each dilution was plated by sterile pipette with 1 ml of dilution into a Petri dish and the respective sterile melted media were poured into the plates. The plates were rotated by hand, a minimum of 5 times clockwise and 5 times in the anticlockwise direction and several times crosswise for equal distribution of the media. After solidifying the media the plates were inverted. Then the plates were incubated at room temperature. Levin’s Eosin Methylene Blue (EMB) agar media were used for identification of the quantity of total E. coli population. Triplicate plates of each dilution were prepared for total E. coli load and the average of the colonies formed in the three plates was recorded. Total plate count was done by multiplying the colonies on the plate by the dilution factor. The average number of the total plate counts of each dilution was considered as total counts. In order to enumerate the E. coli, Levin’s EMB media were used for each sample and incubated at room temperature for 48 h. As the E. coli was very rare in water and soil, so the author did the work without serial dilution. Density of E. coli was estimated by using pour plate techniques. Colonies having a green metallic sheen with dark centre were confirmed as E. coli. The colonies were picked and streaked on the nutrient agar slants and the slants were incubated at room temperature for 48 h. Then the cultures of the slant were subjected to Gram staining, Biochemical test and Fermentation test. For the isolation of single colony. The selected colonies were marked and their cultural and morphological characteristics were recorded. Simple correlation have been calculated.

Source of Information: Journal of Bacteriology Research Vol. 5(1), pp. 1-8, January, 2013

Article Link (Online Journal):

Funding Source:

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Achievement/Findings:

Water of Karnafuly River estuary used for any purpose, may affect people by several health hazard diseases like diarrhea, dysentery, cholera, typhoid etc. With the relation of some relative physio-chemical parameters against E. coli bacteria both in water and soil, it was observed that against temperature, E. coli was insignificantly (1% confidence level) positively correlated whereas negatively correlated against salinity, pH and DO. In the present work, with comparison between the water and soil, it was found that soil sample carries higher total E. coli load than water sample. It may be 2-3 times more than water in all stations of the Karnafuly River estuary. In Karnafuly River area, people suffer from various health hazard diseases due to use of water for drinking, bathing, washing and soil for various household purposes. Water and soil resources and fish species of Karnafuly estuary are contaminated by E. coli. After the study, it is concluded that E. coli bacteria from three stations of the Karnafuly, exceed the standard level both in water and soil, so this water is polluted and unhygienic for drinking and even washing without treatment, which directly affects human health.

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