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 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.
This project addresses these critical Department of Defense (DoD) issues regarding the need for effective monitoring tools that provide certainty in the decision-making process. The in situ toxicity identification evaluation system (iTIES) can address all of these critical risk determinants in a cost-effective manner. It is a biological, fractionation protocol that systematically identifies chemical classes causing toxicity in overlying water, porewater, and outfalls (i.e., industrial/municipal point source and stormwater). The system separates chemical classes of contaminants of concern frequently linked to adverse biological effects (i.e., various types of organics, metals, ammonia) at DoD sites.
This project is being conducted in two phases. The first phase was a proof-of-concept to develop an accurate field methodology for in situ assessment that links chemical class exposures to effects, allowing for more cost-effective monitoring and remediation decisions. This phase is complete and the results are available in the Phase I Final Report. The objective of Phase II is to further optimize the Phase 3 iTIE prototype to expand its applications in a user-friendly design.
The 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:
- identifying the possible groups of contaminants and pathways of concern;
- selecting appropriate absorbents, organisms and endpoints;
- preloading iTIEs in the laboratory or field;
- deployment at the site (6 - 48 h);
- evaluating toxicity and/or biomarker endpoints; and
- 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 proof-of-concept was established for the iTIES in the Phase I effort. The iTIES prototype 3 is now a robust deployable system that allows for consistent and sensitive adjustments to pumping rates of ambient waters through a diagnostic array of resin treatments. The current battery of resins separates the following potential toxicants: ammonia, problematic heavy metals (Ag, Cd, Cu, Ni, Pb, Zn), and organics of various characteristics, including PCBs, PAHs, and per- and polyfluoroalkyl substances (PFAS).
The technical approach for the Phase II effort further optimize the technology to include:
- improve use in sediments via developing diverless deployment modifications,
- modify the water intake system for porewater extractions,
- develop a gentle aeration system to allow for toxicity testing of anoxic pore and surface waters,
- refine chemical targeting (including PFAS) and separation via new resins,
- expand marine and freshwater fish and invertebrate chronic toxicity, and
- further field validate the usefulness of the technology.
From a strategic assessment approach, the iTIE should be viewed as a Tier 2 or 3 level approach for incorporation into a smart weight-of-evidence study. It is a diagnostic tool to be used once Tier 1 assessments suggest chemical toxicity may be a concern. Because most sites contain a plethora of chemicals which may be contributing to toxicity, the iTIE can direct the site manager to focus on those chemicals of greatest ecological concern. In addition, the iTIE can assist in source identification of toxic chemicals whether associated with sediments, caps, ambient waters, stormwaters, or outfalls. (Anticipated Project Completion - 2022)
Burton, G.A., E.C. Cervi, K. Meyer, A. Steigmeyer, E. Verhamme, J. Daley, M. Hudson, M. Colvin, and G. Rosen. 2020. A Novel In Situ Toxicity Identification Evaluation (iTIE) System for Determining which Chemicals Drive Impairments at Contaminated Sites. Environmental Toxicology and Chemistry, 39(9):1746-1754. doi.org/10.1002/etc.4799.