Selecting Bioaccumulation Models for Nonionic Organic Contaminants when Assessing Risk at Contaminated Sediment Sites including the Role of Passive Sampling
Citation:
Burgess, R., A. Parks, S. Kane Driscoll, AND M. Kravitz. Selecting Bioaccumulation Models for Nonionic Organic Contaminants when Assessing Risk at Contaminated Sediment Sites including the Role of Passive Sampling. 14th International Passive Sampling Workshop and Symposium, Limoges, FRANCE, May 12 - 14, 2024.
Impact/Purpose:
Over the last 30 years, several models have been developed to predict bioaccumulation for assessing and managing the risks associated with contaminated sediment sites. These models range from a simple ratio of biota to sediment concentrations to more complex appraoches involving the food web. Selecting which bioaccumulation model to use at a given specific site is not trivial and involves balancing several critical decision considerations. The U.S. Environmental Protection Agency is developing a guidance document that provides an overview of bioaccumulation models for organic contaminants and an approach for selecting the appropriate bioaccumulation model. A relatively new technology called passive sampling is an important component of this guidance. It is expected that this document will assist site managers, scientists and other users to consistently select the optimum model(s) for bioaccumulation-related applications at their contaminated sediment sites.
Description:
Over the last 30 years, several models have been developed to predict bioaccumulation for assessing and managing the risks associated with contaminated sediment sites. These models include simple ratios of biota to sediment concentrations (i.e., biota-sediment accumulation factor (BSAF)), use of passive sampling polymer as a surrogate for organism lipid, and complex food web models that consider metabolic biotransformation and excretion as well as spatial and/or temporal changes. In many cases, passive sampling-based information can also be incorporated into bioaccumulation modeling to improve the predictions compared with conventional metrics. For example, passive sampling-based freely dissolved concentrations (Cfree) are better estimates of bioavailable contaminant than simple ‘total’ contaminant concentrations. Bioaccumulation models have many applications including: (i) predicting concentrations of contaminants in organisms from concentrations in environmental media, (ii) developing site-specific conceptual models and risk assessments, (iii) back-calculating risk-based sediment remedial goals, and (iv) predicting past or future tissue concentrations before or after remediation. However, selecting which bioaccumulation model to use at a given specific site involves balancing several critical decision considerations including (1) investigation objectives such as which contaminants are being monitored and the nature of the decision being made, (2) the level of accuracy and precision needed for the modelled estimate(s), (3) the type of data available, and (4) resources available for applying a given model. The U.S. Environmental Protection Agency is developing a guidance document that provides an overview of bioaccumulation models for nonionic organic contaminants and an approach for selecting the appropriate bioaccumulation model(s) for use at contaminated sediment sites. Inclusion of passive sampling data is part of this guidance. This document will assist site managers, scientists, and other users to consistently select the optimum model(s) for bioaccumulation-related applications at their contaminated sediment sites.
