Passive sampling methods for contaminated sediments: risk assessment and management.

This paper details how activity-based passive sampling methods (PSMs), which provide information on bioavailability in terms of freely dissolved contaminant concentrations (Cfree ), can be used to better inform risk management decision making at multiple points in the process of assessing and managing contaminated sediment sites. PSMs can increase certainty in site investigation and management, because Cfree is a better predictor of bioavailability than total bulk sediment concentration (Ctotal ) for 4 key endpoints included in conceptual site models (benthic organism toxicity, bioaccumulation, sediment flux, and water column exposures). The use of passive sampling devices (PSDs) presents challenges with respect to representative sampling for estimating average concentrations and other metrics relevant for exposure and risk assessment.

Passive sampling methods for contaminated sediments: practical guidance for selection, calibration, and implementation.

This article provides practical guidance on the use of passive sampling methods (PSMs) that target the freely dissolved concentration (Cfree ) for improved exposure assessment of hydrophobic organic chemicals in sediments. Primary considerations for selecting a PSM for a specific application include clear delineation of measurement goals for Cfree , whether laboratory-based "ex situ" and/or field-based "in situ" application is desired, and ultimately which PSM is best-suited to fulfill the measurement objectives. Guidelines for proper calibration and validation of PSMs, including use of provisional values for polymer-water partition coefficients, determination of equilibrium status, and confirmation of nondepletive measurement conditions are defined.

Transitioning sediment quality assessment into regulations: Challenges and solutions in implementing California's sediment quality objectives.

Development and promulgation of sediment quality criteria represents a substantial challenge for water quality agencies. Unlike water quality programs that rely on individual chemical thresholds to assess water quality, the complex processes affecting contaminant bioavailability in sediments preclude the use of contaminant concentrations to independently assess impacts or identify cause. Various multiple line of evidence approaches (e.