Assessing water quality with fluorescence
RESTON, Va. – Fluorescence measurements could help scientists monitor source water
quality, according to a recent US Geological Survey (USGS) study of Oregon’s
The focus of the study was the type, amount and source of dissolved
organic carbon, present in all drinking water sources. During water treatment, dissolved
organic carbon reacts with chlorine to form halogenated compounds known as disinfection
Scientists from the USGS, in collaboration with Oregon’s
Eugene Water and Electric Board, analyzed samples from the McKenzie River mainstream,
tributaries and reservoir outflow, taking optical measurements to assess the full
spectrum of fluorescence and absorption.
Groundwater flows into the upper watershed of the McKenzie River
in Oregon. Courtesy of Tamara Kraus, USGS.
Their results showed that dissolved organic carbon and disinfection
byproduct precursors originated upstream. Downstream, tributaries had higher concentrations
of dissolved organic carbon, but these made up less than 5 percent of the mainstream
flow, which the researchers said means that they do not significantly affect drinking
There was some interference while measuring the absorbance spectra,
but the study presented conclusive evidence that measuring optical properties could
be a cheaper, less time-consuming and more sensitive method of water quality assessment
than laboratory chemical-based analyses, the researchers found.
The study was published in the November-December 2010 issue of
the Journal of Environmental Quality.
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