Environmental Monitoring & Assessment Program

LT Gregory J. Hall, USCG *
Kerin E. Clow †
Hao Chen †
Jonathan E. Kenny †

* U.S. Coast Guard Academy (ds-1) 15 Mohegan Ave, New London, CT 06320
† Tufts University, 62 Talbot Ave, Medford, MA 02155

Time-resolved Excitation Emission spectroscopy provides a four-dimensional data set called a Time-resolved Excitation Emission Matrix (TREEM). This data is well suited for treatment by advanced statistical techniques such as N-way Partial Least Squares (NPLS) regression and Parallel Factor Analysis (PARAFAC). Using these techniques, we have successfully fingerprinted water samples as to their location from several estuaries around the U.S. including the Thames River, Boston Harbor, and the Mystic River in Boston. This work includes the characterization of the fluorescence of water from local estuaries over an 18 month period. Fingerprinting of estuaries is important to the enforcement of ballast water exchange regulations which are crucial in the prevention of aquatic nuisance species.

In the course of this analysis, unusual samples are sometimes encountered. These samples can be further analyzed for their unique spectral characteristics by PARAFAC determining the fluorescent contribution of the anomaly without needing standards. The result of examining the anomalies can yield surprising results of importance to estuarial health, such as a seasonal surge in dissolved polycyclic aromatic hydrocarbons. Results of this powerful technique will be presented, as well as the development progress of a deployable in-situ instrument.

Keywords: Aquatic nuisance species, Ballast water, PARAFAC, NPLS, seasonal variation, TREEM, fluorescence.