Depuration kinetics of TNT and its metabolites in lab exposed blue mussels (Mytilus edulis, L.)

<p>Explosive chemicals released by dumped warfare material pose a threat to the marine environment and can enter the marine food web. These chemicals are toxic and are suspected to be carcinogenic, mutagenic and have also genotoxic effects. 2,4,6-Trinitrotoluene (TNT) is one of the most used explosives in munitions and therefore of special interest. To test the potential uptake, bio-concentration or bio-accumulation, and metabolism or depuration of TNT in marine organisms two lab exposure experiments were conducted using common blue mussels (<em>Mytilus edulis</em>). Mussels were exposed to different TNT concentrations for a specific period of time. The first experiment ran for a total of 120 hours, with 48 hours of exposure to different TNT concentrations (0 mg/L, 0.625 mg/L, 1.25 mg/L and 2.5 mg/L) followed by a 72 hours recovery phase in clean artificial seawater. Mussel sampling took place during the recovery phase.</p><p>The second experiment was performed as follow up to the first experiment and was conducted over 36 hours, with 24 hours of exposure and 12 hours of recovery. Water and mussel samples were taken during exposure and recovery phase with a higher sampling resolution within the first hours of the recovery phase. GC-MS/MS was used to determine the mussel tissue and water concentration of TNT and its metabolites 2-amino-4,6-dinitrotoluol (2-ADNT), 4-amino-2,6-dinitrotoluol (4-ADNT) and 2,4-diamino-6-nitrotoluene (2,4-DANT).</p><p>Results of the first experiment showed a rapid decrease in TNT and metabolite concentrations in mussel tissues over time. Overall, 57 to 76 % of the detected concentration was metabolised within the first four hours after the exposure. Analysis of samples of the second experiment verified the results from the first experiment showing clear linear digression of the two ADNTs within the first four hours of the recovery phase and a more or less complete metabolism of the parent compound TNT.</p><p>In summary, uptake of TNT in relation to the exposure concentration could be proven and first insights concerning the metabolism and depuration velocity could be shown.</p><p>Keywords: TNT, metabolites, 2-ADNT, 4-ADNT, metabolic rate, depuration</p>