Eco-toxicity of Three Nitroaromatics Pollutants to Freshwater Fish Exposed to Controlled Conditions

In order to obtain some basic data for eco-toxicological tests, acute lethal toxicities of o-nitrochlorobenzene, m-nitrochlorobenzene and 2,4-dinitrotoluene in aquatic environment to Brocarded Carp were investigated. Brocarded Carp was employed and introduced into different test solutions contained three compounds. LC₅₀ defined within 96 h was calculated by the mortality of fish using the Karbers method. The pretest showed that the 24 h LC₁₀₀ concentrations of 2,4-DNT, M-NCB, O-NCB were 33, 40, 50 mg/L and 96 h LC₀ concentrations of 2,4-DNT, M-NCB, O-NCB were 6, 20, 25 mg/L, respectively. the most acutely toxic among the tested chemicals was 2,4-DNT, with a LC₅₀ of 19.67 mg/L for Brocarded carp, the 96 h LC₅₀ value of O-CNB and M-CNB were 36.48 mg/L and 33.5 mg/L, respectively. Based on 96 h LC₅₀ values, the rank order of chemicals from most toxic to least toxic was: 2,4-DNT>M-NCB>O-NCB. These results were in consistent with the structure-activity theory. LC₅₀ revealed highly significant linear relationships between the short-time biological endpoints and the dosage of three chemicals. The test results indicated that the number of nitro substituent of nitroaromatics compounds were positive correlation with the acute toxicity of nitroaromatics compounds to fish and the toxicity of nitro substituent was greater than that of chlorine substituent. This paper may give some consults for ecological risk assesses of nitroaromatics compounds and their analogues.