Important considerations in the derivation of background at sediment sites. (4th March 2019)

• Record Type: Journal Article
• Authors: Geiselbrecht, Allison; Rouhani, Shahrokh; Thorbjornsen, Karen; Blue, Douglas; Nadeau, Steven; Gardner‐Brown, Tessa; Brown, Steven
• Is Part Of: Integrated environmental assessment and management. Volume 15:Number 3(2019)
• Page Start: 448
• Page End: 457
• Publication Date: 2019-03-04
• Subjects: Contaminated sediment sites -- Background concentration -- Sediment geochemical evaluations -- Outlier evaluation -- Statistical population comparison; Environmental management -- Periodicals; Pollution -- Periodicals; Environmental toxicology -- Periodicals; Environmental risk assessment -- Periodicals; Environmental impact analysis -- Periodicals; 628
• DOI: 10.1002/ieam.4124
• Languages: English
• ISSNs: 1551-3777

Abstract

ABSTRACT: In the United States, there is an absence of federal guidance related to deriving and applying background concentrations at contaminated sediment sites. This absence has resulted in significant variability, uncertainty, and disagreement regarding how representative background concentrations of chemicals of concern should be derived for these sites. The present article discusses important considerations in the derivation of representative background concentrations to be used in the evaluation of contaminated sediment sites. Specifically, a thorough understanding of a site is critical to selecting the background reference areas from which representative background concentrations can be derived, representative background concentrations should account for contributions from those background chemical inputs (natural and anthropogenic sources) that will continue affecting the site even after remediation, perceived outliers should not be eliminated from the background data set just because they are the highest or lowest values, and geochemical evaluation of trace metals is a useful tool for deriving representative background concentrations. On a site‐specific level, representative background concentrations are critical for putting site‐related risk into context, developing a cost‐effective and technically feasible remedial approach, understanding the potential for recontamination, and ensuring long‐term remedy success. In a broader context, clear guidance from the United State Environmental Protection Agency (USEPA) for deriving and applying background concentrations for contaminated sediment sites would help promote national consistency in site assessment and remedy decision making. Integr Environ Assess Manag 2019;00:000–000. © 2019 The Authors. Integrated Environmental Assessment and Management Published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC) Key Points: Background reference areas should be as similar as possible to the site in terms of surrounding land use and with respect to physical, chemical, geological, and biological characteristics; but importantly, they should not be influenced by site releases. Representative background concentrations should account for input from natural and anthropogenic background sources that will continue to affect the site, allowing for defensible representative background concentrations to be used in remedial investigation, remedy selection, and monitoring. An outlier should not be eliminated just because it is the highest or lowest value in a data set; when the nature of a perceived outlier is unknown or disputed, specific and rigorous statistical analyses should be conducted to evaluate the effect of retaining or eliminating the data point. Once derived, representative background concentrations should remain fixed during remedial investigation, remedial response, and performance monitoring; otherwise, the lack of certainty for stakeholders will be deemed unreasonable and an impediment to the selection and implementation of any remedy.