Sources and behaviour of dinitrotoluene isomers in sea-water

The sources and behaviour of dinitrotoluene (DNT) isomers in the sea-water of Dokai Bay in Japan were investigated. DNT isomers such as 2,6-, 2,5-, 2,4-, 2,3- and 3,4-DNT were identified in an industrial effluent. One drain, the main source, discharged about 150 kg of DNT isomers as the maximum value in a day. This value roughly agrees with that obtained from seven months of monitoring of DNT isomers in sea-water. The monitoring revealed that about 76 kg of DNT isomers was discharged into the bay daily. 2,6-, 2,4- and 2,3-DNT were detected in the sea-water at the levels of 14,8-ND μg l⁻¹ (n = 82), 206-ND μg l⁻¹ (n = 82) and 0.412-ND μg l⁻¹ (n = 82), respectively. The relationship between the concentration of 2,4-DNT (Y) and the distance (X) is statistically expressed by the equation of Y = (6.38 ± 4.02)e^{−(0.269 ± 0.044)X}, and the relationship between the 2,6-DNT/2,4-DNT ratio (y) and the distance (X) is expressed as y = −(0.795 ± 0.131) X + (9.35 ± 4.1). These relationships reveal that the decrease of DNT isomers in the sea-water is caused by factors more complex than mechanical dilution by tidal action.