Departamento de Geoquímica, Instituto de Química, Universidade Federal Fluminense, Niterói, RJ 24020-150, Brazil.
Environ Sci Pollut Res Int. 2011 Jul;18(6):1033-6. doi: 10.1007/s11356-011-0517-1. Epub 2011 May 7.
Metal bioavailability-based sediment quality analysis, inferred from geochemical partitioning data, may contribute to improve sediment management policies. This is important because decision-making processes should not give similar priorities to sediments offering contrasting environmental risks associated to metal bioavailability. However, current uses of Sediment Quality Guidelines (SQGs) as interpretive tools to support decisions about dredging-related activities have not considered the changes in metal bioavailability upon sediment resuspension.
Sediments from a Cu-contaminated site in Guanabara Bay (Brazil) were submitted to 16-h resuspension experiments in estuarine water to assess the susceptibility of Cu mobilization to the dissolved phase and alteration in the solid phase partitioning between a potentially bioavailable (1 mol/l HCl-extractable) phase and concentrated HNO(3)-extractable phase.
After sediment resuspensions, dissolved Cu levels became slightly lower (in a surface water-resuspension treatment) or slightly higher (in a bottom water-resuspension treatment). In both treatments, the 1 mol/l HCl-extractable solid phase concentrations changed from seven times lower to two times higher values than an SQG adopted in Brazilian legislation. This change was explained by a transition from concentrated HNO(3)-extractable phases to reactive HCl-extractable phases upon resuspension.
An evaluation of metal susceptibility to present geochemical partitioning changes, as can be inferred from HCl-extractable fraction analyses before and after resuspension experiments, is recommended as an additional criterion to assess environmental risks of sediment dredging in relation to resuspension-sensitive metals, such as Cu.
基于地球化学分配数据推断金属生物有效性的沉积物质量分析，可能有助于改进沉积物管理政策。这一点很重要，因为决策过程不应给予具有不同金属生物有效性相关环境风险的沉积物相同的优先级。然而，当前将沉积物质量准则 (SQG) 用作支持与疏浚相关活动决策的解释工具时，并未考虑到沉积物再悬浮时金属生物有效性的变化。
对来自瓜纳巴拉湾（巴西）一个 Cu 污染场地的沉积物进行了 16 小时的再悬浮实验，以评估 Cu 向溶解相迁移的敏感性以及潜在生物可利用（1 mol/L HCl 可提取）相与浓 HNO3 可提取相之间固相分配的变化。
在沉积物再悬浮后，溶解态 Cu 水平略有降低（在地表水再悬浮处理中）或略有升高（在底水再悬浮处理中）。在两种处理中，1 mol/L HCl 可提取固相浓度从比巴西法规中采用的 SQG 低 7 倍变为高 2 倍。这种变化是由于再悬浮时从浓 HNO3 可提取相转变为反应性 HCl 可提取相所致。
建议在再悬浮实验前后进行 HCl 可提取分数分析，以评估金属对当前地球化学分配变化的敏感性，作为评估与再悬浮敏感金属（如 Cu）相关的沉积物疏浚环境风险的附加标准。
