Conder Jason M, La Point Thomas W, Steevens Jeffery A, Lotufo Guilherme R
University of North Texas, Department of Biological Sciences, Institute of Applied Sciences, P.O. Box 310559, Denton, Texas 76203, USA.
Environ Toxicol Chem. 2004 Jan;23(1):141-9. doi: 10.1897/03-137.
Previous investigations of the ecotoxicity of TNT in spiked sediments noted the rapid degradation and disappearance of the toxicant, yet little is understood regarding the effects of this process on toxicity and subsequent derivation of toxicity reference values. We conducted environmental fate studies and 28-d sediment toxicity tests with benthic oligochaete worms (Tubifex tubifex) with sediments spiked at three different TNT concentrations (440, 1,409, and 4,403 nmol/g dry wt) aged for 1, 8, and 29 d. Because of rapid degradation of TNT, disappearance of degradation products, and partitioning to overlying water, only 25 to 40% of the added nitroaromatic mass balance was associated with sediment immediately after spiking. Lethal toxicity decreased with aging time and was best described by measured sediment nitroaromatic concentrations (sum of TNT and degradation products) at the beginning of exposure, with a median lethal concentration of nitroaromatic compounds of 184 nmol/g dry weight. To accurately describe the ephemeral exposure doses of TNT and its degradation products during toxicity tests with spiked sediments, we suggest that sediments should be aged at least 8 to 14 d after spiking, exposure should be based on measured sediment concentrations or chemical measures of availability, exchange of overlying water should be avoided or minimized, and short-term toxicity tests should be considered.
先前对添加了三硝基甲苯（TNT）的沉积物进行的生态毒性研究指出，该有毒物质会迅速降解并消失，但对于这一过程对毒性的影响以及随后毒性参考值的推导了解甚少。我们对底栖寡毛类蠕虫（颤蚓）进行了环境归宿研究以及为期28天的沉积物毒性测试，所用沉积物添加了三种不同浓度（440、1409和4403纳摩尔/克干重）的TNT，并分别陈化了1天、8天和29天。由于TNT的快速降解、降解产物的消失以及向上覆水体的分配，在添加后立即测定时，只有25%至40%的添加硝基芳烃质量平衡与沉积物相关。致死毒性随陈化时间而降低，在暴露开始时，用测定的沉积物硝基芳烃浓度（TNT和降解产物之和）能最好地描述这种关系，硝基芳烃化合物的半数致死浓度为184纳摩尔/克干重。为了在对添加沉积物的毒性测试中准确描述TNT及其降解产物短暂的暴露剂量，我们建议，沉积物在添加后应至少陈化8至14天，暴露应基于测定的沉积物浓度或化学有效性测量值，应避免或尽量减少上覆水体的交换，并且应考虑进行短期毒性测试。
