DETERMINATION OF THE ACUTE TOXICITY OF NICKEL (NI) IN WATER ENVIRONMENT TO ZEBRA FISH AT DIFFERENT pH LEVELS

Abstract

The environment has been facing numerous challenges from hazardous wastes, which discharged into water bodies, especially metals which threaten the aquatic life. Metal contents of these hazardous wastes are a threat to aquatic life. The disposal of toxic wastes, like heavy metals (Cd, Ni, Hg, Pb, As) into the water environment adversely affects the aquatic ecosystem and eventually find its way to humans through the food chain. This is the most probable root of potential diseases, affecting human health. Numerous fish species were widely applied to assess the status of aquatic ecosystems. In this study, Danio rerio most commonly known as the zebrafish was used as an bioindicator. This paper aims to determine the acute toxicity of nickel (Ni) at different concentrations (0.2, 0.36, 0.648, 1.166, 2.099 mg/L) to zebrafish in a water environment at different pH levels (6.2; 6.8; 7.3; 7.7). Nickel sulfate hexahydrate (NiSO₄·6H₂O) was used as the Ni source for performing acute toxicity tests (after 48-h exposure [48-h LC₅₀]) with 13-day old zebrafish under the same hardness, dissolved organic carbon (DOC) and alkalinity. The study results highlighted that the nickel acute toxicity to zebrafish declined as pH increased from 7.3 to 7.7, which means the LC₅₀ increased in value as 384.63 and 607.57 µg/L, respectively. The results obtained from this study was expected to bring useful information to find out the exact cause of the increasing mortality of fish.