Predicting the transport and fate of emerging contaminants using multi-tracer characterization of reactive pathways
Contaminants of emerging concern (CECs, unregulated compounds including pharmaceuticals and personal care products) are ubiquitous in environmental and drinking waters, posing potential risks to human and ecosystem health. This proof-of-concept study will characterize the transport and fate of CECs in a stream reach using a suite of tracers with well-characterized, complementary reactivities. Specific research tasks include quantifying reaction pathways within the environmental system, laboratory experiments linking tracer and CEC reaction rates, and numerical modeling to predict transport and fate of CECs. The overall goal of this research is to quantify reaction pathways in the environment and successfully predict the transport and fate of CECs. A major outcome will be a mechanistic understanding of transport and fate processes that can be applied to any CEC in the system; this will enable prediction of the spatial extent and temporal persistence of CECs in streams.
The field work in this SEED grant was conducted at Fourmile Creek in Iowa. Until recently, Fourmile Creek had been an effluent dominated stream, impacted by discharge from nearby wastewater treatment plants. As a result, persistent pharmaceuticals (i.e., those not removed by wastewater treatment) were present in the Creek. However, their analysis is complicated by their trace levels and need for specialized instrumentation and sampling protocols. This SEED grant provided a proof-of-concept demonstration of how an easy-to-analyze trace (i.e., a dye) could be used to assess the fate of these emerging pollutant classes. With further validation and testing, this tracer approach may make it easier to assess the environmental fate of emerging pollutant classes in Iowa waters, and thereby provide better assessment of the risks posed to ecosystem and human health by the persistence of bioactive micropollutants.
There were four important findings.
- The work explored whether a single, reactive tracer could be used to predict the fate of emerging contaminants in surface waters.
- Laboratory studies linked the reactivity of emerging pollutants to that of the reactive tracer, which then allowed the fate of emerging pollutants in the field to be predicted from the fate of the easier to analyze tracer (a dye).
- Field testing yielded mixed results. In some, but not all, instances, the reactive tracer was useful in anticipating the fate of more trace, harder to analyze emerging pollutants (e.g., pharmaceuticals).
- More work is needed to further refine and validate the method.
Ward AS, Cwiertny DM, Kolodziej EP, Brehm CC. Coupled reversion and stream-hyporheic exchange processes increase environmental persistence of trenbolone metabolites. Nature Communications. 2015; 6.doi:10.1038/ncomms8067.