Accumulation of 14C-trinitrotoluene and related nonextractable (bound) residues in Eisenia fetida.

To determine if trinitrotoluene (TNT) forms nonextractable residues in earthworms and to measure the relative degree of accumulation as compared to TNT and its deaminated metabolites, Eisenia fetida was exposed to 14C-TNT using dermal contact to filter paper or exposure to soil. Nonextractable residues made up 32-68% of total body burden depending on exposure media and depuration time. Parent TNT accounted for less than 3% of radioactivity, while ADNTs accounted for 7-38%. Elimination half-lives were 61-120 h for TNT, ADNTs, and DANTs, which was significantly lower than the half-lives found for nonextractable residues, 201-240 h. However, over 80% of the nonextractable residue was solubilized using weak acid (pH 2). Based on our findings that TNT accumulation occurs primarily as nonextractable residues, which have a longer half-life, and that nonextractable residues can be solubilized, we propose that nonextractable residues could be used as a selective biomarker for assessing TNT contamination.

Can site-specific heuristic toxicity models predict the toxicity of produced water?

An empirically derived model of major ion toxicity was combined with other toxicity assessments to account for the observed toxicity in field-collected produced water and produced water contaminated groundwater. The accuracy and precision of the ion toxicity model, calculated using model deviation ratios (MDR) and simple linear regressions, was determined for fathead minnows, Ceriodaphnia dubia, and Daphnia magna. Model accuracy for produced water fell within a factor of two for all three organisms. The precision, or variability explained by the model, was 47.9%, 56.1%, and 0.00% for fathead minnows, C. dubia, and D. magna, respectively. Incorporating other measured potential toxicants improved predictive precision for fathead minnows to 67.0% using ion toxicity and pH and to 30.9% for D. magna using ion toxicity, pH, and total ammonia. The observed toxicity to Daphnia pulex was also evaluated using D. magna model predictions and other measured parameters, but no consistent relationship was found. Dissimilar results were found for produced water contaminated groundwaters with model predictions for D. magna falling within a factor of two of and explaining 53.8% of the observed variability in D. pulex responses. These results indicate that predicted major ion toxicity, combined with other measured parameters, can accurately and precisely account for observed responses in test organisms to field-collected samples.