Stephen Sassman 

Graduate Student

Department: Agronomy


Measurement of contaminant flux in the environment has historically required a multitude of high frequency measurements within carefully defined spatial boundaries. In the case of water born contaminants, which present significant challenges and expense related to collection, transportation, extraction, and analysis when using traditional methods, passive sampling presents a particularly attractive alternative with great potential for development of new techniques. Because traditional sampling can only capture information about the contaminant at the moment and location when the sample was taken, these techniques often miss high flow events which contribute disproportionately to chemical loading or spikes in concentration thus providing an inaccurate assessment of contaminant flux as well as exposure of aquatic organisms. Although flow-proportional sampling using automated equipment can improve estimates of contaminant loading, many samples must still be taken to accurately estimate the contaminant flux and the expense of operation and maintenance of these systems can be prohibitive. 

Alternatively, passive sampling devices provide, with a single sample, an average contaminant concentration over the entire deployment period of the device. This approach can dramatically reduce the number of samples required along with associated costs while still providing equivalent information about the contaminant of interest. My research focuses on development of a Passive Surface Water Flux Meter (PSFM) as a tool for measuring concentration of dissolved and particulate bound contaminants in streams and rivers with specific focus on hormones and herbicides in a ditch/stream network affected by confined animal feeding operations (CAFO). Design parameters of the PSFM are optimized for measurement of trace-level contaminants. Contaminant concentrations measured using the PSFM at various locations within the ditch-stream network are compared to those determined by taking instantaneous measurements of contaminant concentration in water samples at discreet intervals​