NICOP - Improving the assessment of potential impacts from intermittent, short-term, stormwater and effluent discharges to aquatic environments.
Abstract
To determine the risk of toxic effects to aquatic organisms due to discharges of effluentsto the aquatic environment, water quality" criteria (WQC) and direct toxicity assessment(DTA) are the most frequently utilized assessment tools. These approaches predict the"response of organisms to the continuous exposure to the effluent following mixing withthe receiving water. In many environments, i""ntermittent, episodic, fluctuating and pulsedeffluent result in aquatic organisms frequently receiving only short exposures tocont"aminants at concentrations that exceed the chronic criteria. Such variablecontaminant exposures are common for many effluent discha"rges, includingstormwater. While conservative assessment outcomes are desirable owing to the oftencomplex and fluctuating composit""ion of effluents and nature of receiving environments,highly over-conservative assessments of short-term discharges may result inu"nnecessary high costs for treatment or remedial actions.Numerous studies of toxicity to individual contaminants via intermittent ex"posures haveobserved that, regardless of the pulse duration, the toxicity is generally observed to beof a proportional magnitude w""hen considering time averaged concentration. Thiseffectively means that as the exposure duration decreases, the exposure concentrat"ioncan increase proportionally (within an upper tolerance limit) and effects will be similar.When considering the literature colle"ctively, when assessing risks posed by intermittentdischarges, it may be feasible to modify both: (i) the chronic WQC (relaxed by s""omefactor), and (ii) DTA methods (shorter and more representative exposures), to achieveprotective but not highly overly-conservat""ive outcomes. However, owing to knowledgegaps that may indicate potentially important limitations, the acceptance of this scienceh"as not yet been extended from theory to practice and has not yet resulted in thepredicted improvements to management practices.The project will undertake basic research necessary to assess limitations to durationspecificmethods for predicting the potential impa"cts of contaminants that enter aquaticecosystems via intermittent discharges. Specifically, the project will target knowledgegaps"" that may potentially impede science adoption, including challenges associatedwith mixtures of contaminants (common in many effluen""ts), sensitivity of differentorganism life-stage, and the influence of time of exposure (day or night).The management of stormwate"r runoff and other intermittent discharges from Navy /Department of Defense facilities is an ongoing and frequently very costly act"ivity. Theproject will improve the reliability of assessments, and is anticipated to reduce costsassociated with compliance and mi"nimize potentially unnecessary corrective action forboth industry and government.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 29, 2017
- Source ID
- N629091712120
Entities
People
- Stuart L Simpson
Organizations
- Commonwealth Scientific and Industrial Research Organisation
- Office of Naval Research
- United States Navy