Acute Toxicity of the Water-Soluble Fraction of Diesel Oil (WSD) on Beluga (Huso Huso)

Abstract

Among the different types of pollutants, oil production is one of the most significant contaminants of aquatic ecosystems. Acute toxicity tests (96 h) were conducted to determine the lethal toxicity of the water-soluble fraction of diesel oil (WSD) to beluga (Huso huso), a unique and reliable model of commercial fish species in the Caspian Sea. The acute toxicity test was performed in a static renewal system based on the standard method proposed by the OECD over 96 h, during which physicochemical parameters of the test water, including pH, dissolved oxygen, and temperature, were monitored. To determine the lethal range of diesel oil for fish, a range-finding test was carried out in fiberglass tanks containing 200 L of municipal water and 7 fish. The acute toxicity test was then performed in 5 treatments in triplicate. The obtained data were analyzed using probit analysis with a 5% confidence limit. According to the results, the 24 h LC50, 48 h LC50, 72 h LC50, and 96 h LC50 diesel oil on beluga were 36.96%, 33.67%, 23.85%, and 19.42% WSD, respectively. The Maximum Acceptable Toxicant Concentration (MATC) of diesel oil on beluga was 1.94%, and the Lowest Observed Effect Concentration, equal to the 96 h LC50, was 9.554%. The safe level was calculated based on several standard methods. The results indicated that beluga, unlike other aquatic species, is less resistant to diesel oil.