Proof-of-Concept for the in situ Toxicity Identification Evaluation (iTIE) Technology for Assessing Contaminated Sediments, Remediation Success, Recontamination and Source Identification

Allen Burton | University of Michigan



SERDP, ESTCP and other agencies have supported the development of in situ tools for monitoring contaminants and characterizing environmental effects of stormwater, effluents, base flows and sediments, and the effectiveness of associated remedies. For example, a range of passive sampling devices have been developed with associated guidance by ESTCP and USEPA. These provide direct in situ measures of chemical exposure in porewater or surface water, and devices like the  SEA Ring now provide controlled, standardized methodologies for direct in situ assessment of bioaccumulation and toxicity for multiple species and exposure compartments. However, a gap remains with respect to realistic, in situ tools that link measurements of specific chemical exposures with biological effects in a way that provides direct information on the chemicals responsible for observed effects. This critical uncertainty impedes effective management decisions on whether sites must be remediated, which chemicals are responsible for adverse effects, and whether remediation technologies are working well. Monitoring costs are excessive and particularly ineffective in establishing causality and linkages to improved biological communities. At most sites where even the sediment quality triad or other multiple line-of-evidence data are collected, chemical causality is not established and decisions are best professional judgment or regulatory bright-line based. While laboratory toxicity identification evaluation (TIE) methods exist, they suffer from the same lack of realism (being prone to sampling and manipulation artifacts) as shared by other laboratory exposure and effects measurements.

The overall objective of this one year project is to demonstrate a proof-of-concept for an in situ assessment technology that accurately links chemical class exposures with effects, allowing for more cost-effective monitoring and remediation decisions.

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Technical Approach

The In Situ Toxicity Identification Evaluation (iTIE) technology is a biological-chemical fractionation system that systematically identifies causes of toxicity. The iTIE system was created to separate chemical classes of compounds frequently linked to adverse biological effects (i.e. organics, metals, ammonia). The prototype iTIE system consists of a rectangular unit capable of housing an array of iTIE units. Each unit is equipped with an organism exposure chamber; a smaller chamber filled with a resin absorbent to fractionate porewater, surface water or effluent passing through the organism chamber; and a connection to a water collection container.

The system has multiple applications and can be used to assess potential impacts of a variety of chemical groups and exposure pathways (i.e., overlying waters, groundwater-surface water interactions, effluents and/or porewaters) to a range of test organisms. Chemical analyses of water and resins or other absorbents used from each iTIE unit can also be compared to both organism endpoints (e.g., lethality) and in situ exposure biomarkers (sublethal) for a more integrated and environmentally realistic assessment of a wide range of endpoints. Briefly, the process consists of (1) identifying the possible groups of contaminants and pathways of concern; (2) selecting appropriate absorbents, organisms and endpoints; (3) preloading iTIEs in the laboratory or field; (4) deployment at the site (6 - 48 h); (5) retrieval; (6) evaluating toxicity and/or biomarker endpoints; and (7) processing the water and/or resins for chemical analyses. For an improved Weight-of-Evidence (WoE) monitoring and assessment strategy, the iTIEs can be coupled with other monitoring tools, such as the  SEA Ring technology to take advantage of other realistic, flow-controlled water quality monitoring, additional species responses to multiple exposure compartments, and associated deployment and retrieval methods the researchers have already developed and proven.

The technical approach is to (1) refine the current prototype to a more robust design, applicable to a wide range of site conditions, (2) improve the technology to be more user friendly and cost-effective for routine application; (3) and generate pertinent, high-quality data to scientifically demonstrate a proof of-concept as an advancement on the current state of practice for assessing contaminated and remediated sediment sites.

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Traditional TIE procedures are costly and require sample collection and laboratory-based manipulations prone to artifacts and insensitivity. The iTIE system does not suffer from these limitations and provides improved, cost-effective data for decision-making on bioavailable chemical toxicity; proof of the dominant chemical type driving toxicity in the presence of chemical mixtures; an indication of whether sediments are significantly contaminated or remediation treatments are working; and assistance in identifying source contamination. This technology can be a key component in evidence-based decision making regarding the sources of toxicity and impairment in receiving waters. This allows for more informed and cost-effective decisions related to remediation, restoration, and best management practices (BMPs) at DoD sites. (Anticipated Project Completion - 2019)

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Points of Contact

Principal Investigator

Dr. G. Allen Burton Jr.

University of Michigan

Phone: 734-763-3601

Fax: 734-764-8510

Program Manager

Environmental Restoration