Evaluation of heavy metal accumulation in some tissues of the edible fish from the river Satluj in Punjab

Abstract

Heavy metals have long been recognized as one of the most important pollutants in the river waters. In Punjab, the river Satluj gets heavily polluted by domestic sewage, agricultural run-off and effluent discharged from several types of industrial units which may contain heavy metals. The people in Punjab consume a large amount of fish. Most of the fishes sold in the market are captured from the local water area of the river. It is likely that the metals may get deposited in fish, and through the food-chain can enter the humans and threaten their health. With this in mind, a study was planned to determine levels of heavy metals in edible fishes of Satluj river collected from four stations. These are Mystus seenghala, Cirrhinus mrigala, Cyprinus carpio and Labeo rohita. The results of this study provide valuable information on the metal contents in water, sediment and fish from different sampling stations of the river Satluj. Cadmium, Chromium, Nickel and Lead levels in water were found to cross the permissible limit at site-II and III. Metals levels in sediment were found to follow the trend: site-III > site-II > site-IV > site-I. Among the four fishes, Mystus seenghala showed the highest accumulation of the metals followed by Cyprinus carpio, Cirrhinus mrigala and Labeo rohita. Fish liver exhibited highest tendency to accumulate all investigated metals while the accumulation of metals was minimum in the brain. Kidney and muscle have more or less similar amount of metals. The results of the present study have, beyond doubt, indicate that metals have made their entry into the fish tissues. Their presence has been observed in muscle (the most popularly consumed tissue) as well as liver, kidney and brain. Contents of all the metals are within the permissible limits. At present, therefore, the fish in Punjab is safe for consumption. But at the same time, the very presence of metals in fish tissues is a matter of serious concern as heavy metals even in low concentrations are hazardous to fish. Furthermore, a comparison with previous studies on the Satluj water shows that there is an overall increase in metal contents over the last two decades. It is, therefore, suggested that metal pollution, if ignored, can lead to alarming state and steps should be taken to curb it.