Page David S, Boehm Paul D, Stubblefield William A, Parker Keith R, Gilfillan Edward S, Neff Jerry M, Maki Alan W
Bowdoin College, Chemistry Department, Brunswick, Maine 04011-8466, USA.
Environ Toxicol Chem. 2002 Jul;21(7):1438-50.
An 1-year study of the 1989 Exxon Valdez oil spill found that spill residues on the oiled shorelines rapidly lost toxicity through weathering. After 1990, toxicity of sediments remained at only a few heavily oiled, isolated locations in Prince William Sound (AK, USA), as measured by a standard amphipod bioassay using Rhepoxynius abronius. Data from 648 sediment samples taken during the 1990 to 1993 period were statistically analyzed to determine the relationship between the total concentration of 39 parent and methyl-substituted polycyclic aromatic hydrocarbons (defined as total polycyclic aromatic hydrocarbons [TPAH]) and amphipod mortality and the effect of oil weathering on toxicity. A logistic regression model yielded estimates of the lower threshold, LC10 (lethal concentration to 10% of the population), and LC50 (median lethal concentration) values of 2,600, 4,100, and 10,750 ng/g TPAH (dry wt), respectively. Estimates of the threshold and LC50 values in this field study relate well to corresponding sediment quality guideline (SQG) values reported in the literature. For sediment TPAH concentrations >2,600 ng/g, samples with high mortality values (>90%) had relatively high fractions of naphthalenes and those with low mortality (<20%) had relatively high fractions of chrysenes. By 1999, the median sediment TPAH concentration of 117 ng/g for the post-1989 worst-case sites studied were well below the 2,600 ng/g toxicity threshold value, confirming the lack of potential for long-term toxic effects. Analysis of biological community structure parameters for sediment samples taken concurrently found that species richness and Shannon diversity decreased with increasing TPAH above the 2,600 ng/g threshold, demonstrating a correspondence between sediment bioassay results and biological community effects in the field. The low probability of exposure to toxic concentrations of weathered spill residues at the worst-case sites sampled in this study is consistent with the rapid overall recovery of shoreline biota observed in 1990 to 1991.
一项针对1989年埃克森·瓦尔迪兹号油轮漏油事故的为期一年的研究发现，受油污染海岸线的溢油残留物通过风化迅速失去毒性。1990年之后，按照使用阿氏真宽水蚤的标准双壳类生物测定法测量，沉积物的毒性仅在阿拉斯加威廉王子湾少数几个受严重油污染的孤立地点存在。对1990年至1993年期间采集的648个沉积物样本的数据进行了统计分析，以确定39种母体和甲基取代多环芳烃（定义为总多环芳烃[TPAH]）的总浓度与双壳类死亡率之间的关系，以及油风化对毒性的影响。一个逻辑回归模型得出的估计值显示，较低阈值LC10（使10%的种群致死的浓度）和LC50（半数致死浓度）值分别为2600、4100和10750纳克/克TPAH（干重）。该现场研究中阈值和LC50值的估计与文献中报道的相应沉积物质量指南（SQG）值密切相关。对于沉积物TPAH浓度>2600纳克/克的情况，死亡率高（>90%）的样本中萘的比例相对较高，而死亡率低（<20%）的样本中 Chrysene 的比例相对较高。到1999年，对1989年后研究的最坏情况地点的沉积物TPAH浓度中位数为117纳克/克，远低于2600纳克/克的毒性阈值，证实不存在长期毒性影响的可能性。对同时采集的沉积物样本的生物群落结构参数进行分析发现，当TPAH浓度超过2600纳克/克阈值时，物种丰富度和香农多样性会随着TPAH浓度的增加而降低，这表明沉积物生物测定结果与现场生物群落效应之间存在对应关系。在本研究中采样的最坏情况地点，接触风化溢油残留物有毒浓度的可能性较低，这与1990年至1991年观察到的海岸线生物群的快速全面恢复情况一致。
