M. Safiur Rahman
Environmental Analytical Chemistry Laboratory, Institute of Nuclear Science and Technology, Bangladesh Atomic Energy Commission, GPO Box 3787, Dhaka 1000, Bangladesh
A. Hossain Molla
Department of Applied Chemistry and Chemical Engineering, Faculty of Engineering, University of Rajshahi, Rajshahi 6205, Bangladesh
Narottam Saha
Department of Applied Chemistry and Chemical Engineering, Faculty of Engineering, University of Rajshahi, Rajshahi 6205, Bangladesh
Atiqur Rahman
Department of Applied Chemistry and Chemical Technology, Faculty of Applied Science and Technology, Islamic University, Kushtia 7003, Bangladesh
Heavy metals, Health risks, Fish muscle, Bangshi River
Bangshi River, Savar, Dhaka, Bangladesh
Risk Management in Agriculture
Sampling site: The 238 km long Bangshi River is an important river in central Bangladesh. It originates in Jamalpur and passes through Tangai, Ghazipur and Savar before flowing into Dhaleshwari River. In Savarit flows through densely populated towns and agricultural fields that were used as a source of water in the past. Now it is used as a convenient means for disposing of untreated liquid wastes from the Dhaka Export Processing Zone (DEPZ). Although pharmaceutical industries, poultry farms and a tannery have been established there, textile manufacturers, including dyeing and printing units, dominate the area. As a consequence, Bangshi River is being polluted by increasing the concentration of different kinds of pollutants including heavy metals, putting thousands of people of 12 villages in this area into a tremendous health hazard. Thus, Bangshi River has been selected for this study .2.2. Sample collection and preservation: Ten species of fish available in Bangshi River were collected directly from fishermen during pre-monsoon and post-monsoon.The species were Mastacembelus armatus (common Bengali name Baim), Gudusia chapra (Chaplia), Puntius ticto (Puti), Notopterus not-opterus (Foli), Corica soborna (Kachki), Setipinna phasa (Fhassa), Amblypharyngodon mola (Mola), Mystus vittatus (Tengra), Heterpon-eustes fossils( Singh), Clupisoma pseudeutropius (Batashi). Immediately after collection fish samples were was held thoroughly with fresh water in order to remove mud or other fouling substances and put in clean polythene bag to transport the fish samples into the analytical chemistry laboratory of the Institute of Nuclear Science and Technology, BAEC. After transportation to the laboratory, the fish samples were allowed to reach room temperature and non-edible parts were removed with the help of a steam cleaned stainless steel knife. The edible portion of the fish samples was then washed with distilled water and cut into small pieces (2–3 cm) using the cleaned knife over a clean polyethylene sheet. The samples were then air-dried to remove the extra water. Finally, the muscle tissues were oven-dried until the constant weight was obtained. The dried samples were powdered in a glass mortar, sieved through 1 mm mesh and stored in airtight plastic vials inside desiccators. 2.3. Digestion: The dried fish samples were digested according to the method described in Hanson (1973). For this, 0.5 g of powdered fish was taken in a digestion apparatus and 2.5 ml of conc. H2SO4 and 4.0 ml conc. HNO3 was introduced. When the initial vigorous reaction subsided, the mixture was heated slowly on an oil bath, with the addition of 3/4 drops of H2O2. This step was repeated till the solution became clear. The mixture was heated for an additional 20 min. at about 150°C and allowed to cool to room temperature (Rahman, 2004). The content was diluted with deionized water and filtered quantitatively into a 50 ml volumetric flask. 2.4. Analytical methods: The solutions were analyzed for Pb, Cd, Ni, Cr, Cu, Zn, Mn, and Asby atomic absorption spectrophotometry (Model AA-6800, Shima-dzu Corporation, Japan) using air-acetylene flame with a digital readout system. Analytical conditions for the measurement of the heavy metals in aqueous solution using AAS. The instrument calibration standards were made by diluting standard (1000 ppm) supplied by Wako Pure Chemical IndustryLtd., Japan. The results were expressed as mg/kg or ppm of dry weight. Double distilled water was used throughout the study. All glassware and containers were thoroughly cleaned, finally rinsed with double distilled water several times and air-dried prior to use. 2.5. Accuracy check: The analytical procedure was checked using standard reference material MA-A-2 (TM), fish flesh homogenate and MA-B-3 (TM), lyophilized fish tissue. These fish samples were prepared and provided by the International Atomic Energy Agency (IAEA), Vienna. The results indicated a good agreement between the certified and observed values. The standard deviations of the means observed for the reported certified materials were between 1–7%and the percentage recovery was between 95–106% as shown inTable 2.2.6. Statistical analysis: All samples were collected and analyzed in duplicate and the duplicate tests were statistically similar in paired-samplest-test, at 95% significance. The average results were used to represent the data. Statistical software, Minitab 16.0 for Windows, was used to test two-way analysis of variance (ANOVA) at 95% significance to investigate the effect of seasons and different fish species on the variation of the metal concentrations in studied fishes. Other calculations were performed by Microsoft Excel 2010.
Food Chemistry 134 (2012) 1847–1854
Journal