TP1 Sediment Quality Assessment Case Studies
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1:20 PM - 4:40 PM, Tuesday
() Toxic effects of ammunition (TNT) dumping in a marine sediment-water system in situ.
Ek, H.1, Dave, G.1, Nilsson, E.1, 1 Applied Environmental Science, Göteborg University, Göteborg, Sweden
ABSTRACT- 2,4,6-trinitrotoluene (TNT) is the major explosive ingredient in ammunition dumped into lakes and sea after World War II. The objective of the present study was to study the toxicity of sediment close to ammunition over time. Anti Aircraft defence shells were cleaved longitudinally to expose TNT. Each half shell was placed in an open box filled with sediment. Three boxes with sediment and a cleaved shell, and two control boxes with sediment were placed at the sea bottom at a water depth of 17-20 m. Sediment samples were taken in duplicate in each box after 0 (start), 12, 37, 88 and 106 weeks by scuba divers from the Swedish military armed forces. The sediments were tested for toxicity with bioassays using Nitocra spinipes (96 h), Hyalella azteca (96 h) and Daphnia magna (24 and 48 h). No toxicity was found at the beginning of the study. Hyalella and Daphnia bioassays showed no trends in toxicity over time. The toxicity to Nitocra spinipes increased significantly with time in all boxes with adjusted R2 of 0.62 and 0.47 for the control boxes, and 0.68, 0.98, 0.76 for the boxes with shells. After approximately 2 years, the percentage of immobility to Nitocra was 26 ± 12 and 52 ± 7 (mean ± SD) for control boxes and boxes with shells, respectively. The toxicity to Nitocra correlated with TNT concentrations in sediment analysed spectrophotometrically. In the near future, the sediments will be analysed with a more specific method using GC-MS. This study suggests that the survival of sensitive organisms, e.g., Nitocra, might be negatively affected at an ammunition dumping site. However, this study with a relatively large exposed TNT-area in a box filled with sediment may represent a worst-case scenario. The exposure at a real ammunition dumping site is probably less intense but also more chronic.
Key words: sediment, 2,4,6-trinitrotoluene, bioassay, toxicity