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Determining CDOM Absorption Spectra in Diverse Coastal Environments Using a Multiple Pathlength, Liquid Core Waveguide System. Measuring the Absorption of CDOM in the Field Using a Multiple Pathlength Liquid Waveguide SystemWe evaluated the accuracy, sensitivity and precision of a multiple pathlength, liquid core waveguide (MPLCW) system for measuring colored dissolved organic matter (CDOM) absorption in the UV-visible spectral range (370-700 nm). The MPLCW has four optical paths (2.0, 9.8, 49.3, and 204 cm) coupled to a single Teflon AF sample cell. Water samples were obtained from inland, coastal and ocean waters ranging in salinity from 0 to 36 PSU. Reference solutions for the MPLCW were made having a refractive index of the sample. CDOM absorption coefficients, a(sub CDOM), and the slope of the log-linearized absorption spectra, S, were compared with values obtained using a dual-beam spectrophotometer. Absorption of phenol red secondary standards measured by the MPLCW at 558 nm were highly correlated with spectrophotometer values (r > 0.99) and showed a linear response across all four pathlengths. Values of a(sub CDOM) measured using the MPLCW were virtually identical to spectrophotometer values over a wide range of concentrations. The dynamic range of a(sub CDOM) for MPLCW measurements was 0.002 - 231.5/m. At low CDOM concentrations (a(sub 370) < 0.1/m) spectrophotometric a(sub CDOM) were slightly greater than MPLCW values and showed larger fluctuations at longer wavelengths due to limitations in instrument precision. In contrast, MPLCW spectra followed an exponential to 600 nm for all samples. The maximum deviation in replicate MPLCW spectra was less than 0.001 absorbance units. The portability, sampling, and optical characteristics of a MPLCW system provide significant enhancements for routine CDOM absorption measurements in a broad range of natural waters.
Document ID
20050041813
Acquisition Source
Stennis Space Center
Document Type
Preprint (Draft being sent to journal)
Authors
Miller, Richard L. (NASA Stennis Space Center Stennis Space Center, MS, United States)
Belz, Mathias (World Precision Instruments, Inc. Sarasota, FL, United States)
DelCastillo, Carlos (NASA Stennis Space Center Stennis Space Center, MS, United States)
Trzaska, Rick (GB Technology, Inc.)
Date Acquired
September 7, 2013
Publication Date
October 1, 2000
Subject Category
Oceanography
Report/Patent Number
SE-2000-11-0020-SSC
Meeting Information
Meeting: Ocean Optics 15th Conference
Country: Monaco
Start Date: October 16, 2000
End Date: October 20, 2000
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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