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Sci Total Environ. 2010 Dec 1;409(1):83-94. doi: 10.1016/j.scitotenv.2010.09.028. Epub 2010 Oct 20.
A screening-level ecological risk assessment was applied to two extensive, but previously unanalyzed datasets from the middle Rio Grande (MRG) in New Mexico. The assessment evaluated how adverse water-quality effects from aquatic toxicants may have influenced the population decline of the endangered Rio Grande silvery minnow (Hybognathus amarus; silvery minnow). Standardized US Environmental Protection Agency (USEPA) screening-level ecological risk assessment procedures were applied to chemicals assessed in samples collected from the MRG between 1985 and 2003. Since more chemicals have established risk-screening criteria, relative to water-quality criteria, this approach produces more complete assessments. Chemical concentrations at some locations and times were potentially sufficient to affect fish health or produce localized mortalities. Many constituents displaying the highest risks have substantial natural sources within the watershed; native species likely would have adapted to natural instream concentrations such that actual risks might be markedly less than projected by a risk screening based on generic aquatic-life criteria. Also, highest risks found for individual and combinations of contaminants were very inconsistent both within and across the sites. As such, this risk assessment does not support the conclusion that toxicants were a primary factor causing the silvery minnow population to decline in the MRG between 1985 and 2003. The assessment indicates that sediment-borne, relative to water-borne, contaminants appeared to present the greatest risks to the silvery minnow and thus should have increased focus during future assessments of potential contaminant effects in the MRG. Contaminants of greatest concern are identified. This study presents approaches to cost-effectively assess and reduce uncertainties associated with potential water quality effects, and to help direct future assessments of water quality onto those contaminants likely to produce potentially significant effects. The techniques presented and criteria compiled are suitable for aiding similar assessments in other aquatic habitats.
对新墨西哥州里奥格兰德河中游（MRG）的两个广泛但以前未分析的数据集进行了筛选水平的生态风险评估。该评估评估了水生毒物的不良水质影响如何可能影响濒危的里奥格兰德银色小鱼（Hybognathus amarus；银色小鱼）的种群减少。应用了标准化的美国环境保护署（USEPA）筛选水平生态风险评估程序，对 1985 年至 2003 年期间从 MRG 采集的样本中评估的化学物质进行了评估。由于与水质标准相比，有更多的化学物质建立了风险筛选标准，因此这种方法可以进行更完整的评估。在某些地点和时间，化学物质的浓度可能足以影响鱼类健康或导致局部死亡。在流域内，许多显示出最高风险的成分都有大量的天然来源；本地物种可能已经适应了河流中的自然浓度，因此实际风险可能明显低于基于通用水生生物标准的风险筛选预测的风险。此外，在各个地点和地点之间，发现单个和组合污染物的最高风险非常不一致。因此，本风险评估不支持有毒物质是导致 1985 年至 2003 年间 MRG 银色小鱼种群减少的主要因素的结论。评估表明，与水载污染物相比，沉积物携带的污染物对银色小鱼构成的风险最大，因此在未来对 MRG 中潜在污染物影响进行评估时，应更加关注这些污染物。确定了最令人关注的污染物。本研究提出了以具有成本效益的方式评估和减少与潜在水质影响相关的不确定性的方法，并有助于指导未来对可能产生潜在重大影响的污染物进行水质评估。提出的技术和编制的标准适用于协助其他水生栖息地的类似评估。
