Research Areas > Contaminants > Direct Effects in Bays > Integrating Multiple Lines of Evidence

Project Component: Integrating Multiple Lines of Evidence

Background and Objectives

To produce a scientifically defensible and holistic sediment assessment, the three lines of evidence related to sediment quality (chemistry, toxicity, and biological community) must be evaluated and integrated in a consistent manner. There are numerous approaches for integrating multiple lines of evidence (MLOE), but most rely at least partially on best professional judgment, which can be problematic when applied on a large scale where the assessment protocol needs to be transparent and consistently reproducible. The objectives of this project were to (1) develop an approach for standardizing sediment quality assessments based on MLOE, and (2) evaluate the extent to which it captures and reproduces the assessments of experts employing best professional judgment on the same data.

Status

This study was completed in 2008.

Methods

SCCWRP researchers developed a framework for assessing sediment quality that was based on the integration of data from three lines of evidence. The integration process includes three steps:

1) To start, the results from each of the three lines of evidence are placed into the following categories:

• Reference or No Effect (No difference from background conditions)
• Low (A small response that might not be statistically distinguishable from background conditions)
• Moderate (A response that is clearly distinguishable from background)
• High (A large response indicative of extreme conditions)

2) Next, the chemistry and biology response categories are each combined with the toxicity category separately to evaluate two components of ecological risk: the severity of effects on the biological community and the potential for biological effects from chemical exposure. For example, if the benthic community shows a "low disturbance" and the toxicity test displays "moderate toxicity," then the level of biological effect is classified as "low effect."

3) The results of these two ecological risk elements are then integrated to determine the overall site condition. The Severity of Biological Effect category (Unaffected, Low, Moderate, or High) and Potential for Chemically-Mediated Effect category (Minimal, Low, Moderate, or High) are compared to determine the final site condition category, based on a standardized table.

Findings

When results from this integration framework were compared to the evaluation of the same data by a group of experts, the framework was found to have comparable accuracy and a low level of bias. SCCWRP has recently applied this framework to regional monitoring data throughout California to produce a statewide assessment of sediment quality.

A draft technical support manual was prepared to provide instructions for measuring sediment quality parameters, data integration, and interpretation.

Partners

San Francisco Estuary Institute

Presentations

• Development of the Technical Foundation for California's Sediment Quality Objectives - September 2007 presentation to State Water Resources Control Board. Overview of the conceptual approach and tool development activities for assessing the direct effects of sediment contaminants in bays.

• Development and Validation of a Framework for Integrating Sediment Quality Data - January 2007 presentation at the Remediation of Contaminated Sediments Conference. Describes the multiple lines of evidence station assessment framework and the results of a comparison of the framework to assessments by experts.

• Statewide Assessment of Embayment Sediment Quality Using a Multiple Lines of Evidence Framework - Based on a July 2007 presentation at SCCWRP. Describes the results of an application of the sediment quality assessment tools and data integration framework to regional monitoring data in order to produce a spatial assessment of sediment quality in California embayments.

Tools

• Direct Effects Assessment Sample Calculation - Document describing the calculations needed to interpret chemistry, toxicity, and benthic infauna data for sediment quality assessment. Calculations are illustrated using a sample data set.

• LOE Relationship Table - This table displays combinations of the three lines of evidence (toxicity, chemistry, and benthic community) and the sequence of their integration into a single multiple lines of evidence assessment.

• MLOE Assessment Categories Table - A listing of the site assessment categories resulting from each of the 64 possible combinations of the chemistry, toxicity, and benthic community lines of evidence. The list is sorted by chemistry category.

• Data Integration Tool v5.4 - An Excel workbook that contains formulas for combining MLOE data to produce a station assessment.

• List of updates made to the Data Integration Tool

• Complete list of SQO tools