Abstract:
In this study, water quality and toxicity level in the water reservoir of Shahpur dam, Attock district was investigated to evaluate the metal pollution load from anthropogenic and natural sources and their toxic effects on aquatic life. The reservoir is used for irrigation purpose, develop fish culture and as a source of fresh water supply to the surrounding areas. As a comparison, the government fisheries farm conserve the fish, produce and provide fish seed for the dams including Shahpur dam. Total 21 water and 10 fish (Cyprinus carpio) samples were collected from various locations of dam and fish farm as per standard protocols. Physico-chemical parameters including pH, TDS, EC, turbidity, BOD, and COD were determined in water samples. Heavy metals including Pb, Cu, Cr, Fe, and Ni were evaluated by adopting digestion process in water samples and in various organs of fish by using atomic absorption spectrophotometer that were compared with WHO standards. Pb and Cr concentrations were high than WHO limits in water samples following the order water samples[Dam] Pb > Cr > Ni > Fe > Cu and water samples[Farm] Pb > Fe > Cu > Cr > Ni. Whereas, MPI was found high in fish liver[Dam fish] (381.59), liver[Farm fish] (1.64) and gills[Dam fish] (10.78), gills[Farm fish] (2.49) followed by muscles, kidneys and brain. Toxicity potential of metal pollution was determined in the form of oxidative stress by analyzing Catalase (CAT), glutathione S-transferase (GST), and reduced glutathione (GSH) activities in liver and gills of Cyprinus carpio by using UV spectrophotometer. The CAT activity was found higher with inhibition of 41.1% and 2.1% (P = 0.0021 for ANOVA test) in liver and gills of dam fish indicating regulated metabolism and normal process as compared to farm fish samples, in which weak metabolic system was expected. Whereas, GST activity with inhibition of 29.4% and 28.1% (P = 0.0035) and GSH activity with inhibition of 12.8% and 13.9% (P = 0.01) in liver and gills of dam fish were observed high showing positive bond between activities of GST and GSH but the high consumption of these two enzymes during rapid process was supposed to be resulted in oxidative stress in the dam fish. Hence, the metals have toxic effects on the health of fish in the form of oxidative stress. Humans consuming the contaminated water and edible fish are also prone to negative impacts of contaminants specifically the metals bioaccumulations.
