Development and application of the simulated earthworm gut (SEG) technology for soil toxicity testing

Contaminants can become “trapped” in soil over time because of various chemical and biological processes. Trapped contaminants do not cause toxic effects in plants and soil animals even if it is detectible by chemical methods. Therefore, soil contaminant concentration can exceed established safety standards but represent minimal risk to soil organisms if the contaminant is trapped. Growing earthworms in contaminated soil is a common method to evaluate the toxic effects of contaminants in soil; however, this process is time consuming. Alternatively, contaminant concentration in soil can be determined by chemical extraction and analysis. This approach is fast, but harsh chemical extractions often over estimate the risk because contaminants trapped in soil may be extracted as well thereby suggesting danger when there is none. Arguably, it is better safe (i.e., overestimating potential danger) than sorry; however, cleaning up soils that pose no actual danger wastes resources that can be used to remediate real problem areas. We designed the Simulated Earthworm Gut (SEG) to mimic the earthworm’s gastrointestinal fluid composition under the theory that soil contaminants that are extractable by the SEG would be representative of the contaminant exposure that an earthworm would experience. The SEG is not an accepted method at this time. The purpose of this internship is to complete work that will move the SEG towards regulatory acceptance and commercialization.

Faculty Supervisor:

Dr. Steven Siciliano

Student:

Wai Ma

Partner:

Stantec Consulting Ltd.

Discipline:

Geography / Geology / Earth science

Sector:

Environmental industry

University:

University of Saskatchewan