Meeting Abstract
In flowing environments, the movement and distribution of anthropogenic chemicals are determined by the degree of turbulent flow. As such, toxicant exposure for stream organisms is shaped by flow. Whether a toxicant enters a stream through runoff or via groundwater contamination plays a large role in how that toxicant will move through the stream environment. The interaction of the toxicant mode of entry and stream hydrodynamics creates spatio-temporal variation in toxicant concentration. In different locations within a stream, the processes which give rise to chemical plume structure will vary as a function of local stream characteristics. Using an electrochemical recording system to extract data for the frequency, magnitude, and duration of exposure in artificial stream systems, we gain insight into how toxicant “hot spots” form in streams with different flow characteristics. From these measurements, geographic information systems and interpolation techniques can be used to predict chemical distribution throughout habitats. These methods were utilized to compare patterning of toxicant “hot spots” in streams of different flow velocities, with both mode of toxicant introduction (groundwater or runoff) and organism position in the water column (benthic, mid water column, or surface) taken into consideration. Variation in the structure of chemical exposure was used to construct three-dimensional toxicant hot-spot maps, accounting for the spatial and temporal fluctuations of fine scale exposure. This project aids in developing more realistic appraisal techniques for impacts of chemical pollution in flowing environments. Experimental systems must be designed to account for temporal and spatial variability in chemical concentrations at scales relevant to organisms of interest.
