US Fish and Wildlife Service, Spokane, Washington, USA.
Integr Environ Assess Manag. 2011 Oct;7(4):596-611. doi: 10.1002/ieam.261. Epub 2011 Aug 24.
Previous assessment of ecological risks within the Coeur d'Alene River Basin identified Pb as a key risk driver for ground-feeding songbirds. Because this conclusion was based almost exclusively on literature data, its strength was determined to range from low to moderate. With the support of the US Environmental Protection Agency (USEPA), the US Fish and Wildlife Service collected site-specific data to address the uncertainty associated with Pb risks to songbirds. These data, plus those from the previous Coeur d'Alene Basin ecological risk assessment, were integrated, and risks to ground-feeding songbirds were reevaluated. These site-specific data were also used to develop updated preliminary remedial goals (PRGs) for Pb in soils that would be protective of songbirds. Available data included site-specific Pb concentrations in blood, liver, and ingesta from 3 songbird species (American robin, song sparrow, and Swainson's thrush), colocated soil data, and soil data from other locations in the basin. Semi-log regression models based on the association between soil Pb and tissue Pb concentrations were applied to measured soil concentrations from the previous risk assessment to estimate Pb exposures in riparian and adjacent upland habitats throughout the Coeur d'Alene Basin. Measured and estimated tissue or dietary exposure was tabulated for 3 areas plus the reference, and then compared to multiple effects measures. As many as 6 exposure-effect metrics were available for assessing risk in any one area. Analyses of site-specific tissue- and diet-based exposure data indicate that exposure of ground-feeding songbirds to Pb in the Coeur d'Alene Basin is sufficient to result in adverse effects. Because this conclusion is based on multiple exposure-effect metrics that include site-specific data, the strength of this conclusion is high. Ecological PRGs were developed by integrating the site-specific regression models with tissue and dietary effect levels to create exposure models, which were solved for the soil concentration that produced an exposure estimate equal to the effect level (i.e., the ecological PRG). The lowest PRG obtained for any species' exposure-effect measure combination was 490 mg/kg for subclinical effects due to Pb in the blood of American robins; the highest was 7200 mg/kg for severe clinical effects due to Pb in the blood of song sparrows. Because the lowest ground-feeding songbird PRG was comparable to multiple cleanup goals developed for the basin (i.e., soil invertebrates, wildlife populations, and human health), in addition to the site-specific cleanup level of 530 mg Pb/kg sediment for the protection of waterfowl (USEPA 2002) the USEPA has made a risk-management determination that a site-specific Pb cleanup level of 530 mg/kg in soil would be protective of songbirds in the Coeur d'Alene Basin.
先前对科达伦流域生态风险的评估确定 Pb 是地面觅食鸣禽的关键风险驱动因素。由于这一结论几乎完全基于文献数据，其强度被确定为低到中等。在美国环境保护署（USEPA）的支持下，美国鱼类和野生动物管理局收集了特定地点的数据，以解决与 Pb 对鸣禽的风险相关的不确定性。这些数据，加上先前科达伦流域生态风险评估中的数据，被整合在一起，重新评估了地面觅食鸣禽的风险。这些特定地点的数据还被用于为土壤中的 Pb 制定更新的初步补救目标 (PRG)，以保护鸣禽。可用数据包括来自 3 种鸣禽（美洲知更鸟、歌雀和斯旺森鸣鸟）的血液、肝脏和摄入物中的特定地点 Pb 浓度、共置土壤数据以及流域其他地点的土壤数据。基于土壤 Pb 与组织 Pb 浓度之间关联的半对数回归模型被应用于先前风险评估中的测量土壤浓度，以估算整个科达伦流域的河岸和相邻高地栖息地中的 Pb 暴露情况。为 3 个地区加上参考地区列出了测量和估计的组织或饮食暴露情况，然后与多个效应度量进行了比较。在任何一个地区，都有多达 6 个暴露-效应指标可用于评估风险。对特定地点的组织和饮食暴露数据的分析表明，科达伦流域地面觅食鸣禽对 Pb 的暴露足以导致不良影响。由于这一结论是基于包括特定地点数据在内的多个暴露-效应指标得出的，因此该结论的强度很高。生态 PRG 是通过将特定地点的回归模型与组织和饮食效应水平整合创建暴露模型来制定的，该模型解决了产生与效应水平相等的暴露估计值的土壤浓度（即生态 PRG）。由于鸣禽的最低 PRG 与为流域制定的多个清理目标（即土壤无脊椎动物、野生动物种群和人类健康）相当，再加上为保护水禽制定的特定地点清理水平 530 毫克 Pb/kg 沉积物（USEPA，2002 年），美国环保署已做出风险管理决定，即科达伦流域土壤中特定地点的 530 毫克 Pb/kg 清理水平将保护鸣禽。
