Optical absorption of pure water and sea water using the integrating cavity absorption meter

The Integrating Cavity Absorption Meter (ICAM), has been refined to enhance stability, sensitivity, and operational wavelength regions. The ICAM is, in principal, independent of scattering effects in the sample. The ICAM produces an effective path length which is on the order of several meters, consequently, the instrument is sensitive to small absorptions. Measurement results have resolved absorption coefficients as low as 0.004 m^-1. We present definitive results for the absorption spectra of pure water between 380 and 750 nm. The ICAM was field tested on board the USNS Bartlett during the GOMEX-1 cruise in the Gulf of Mexico during April of 1993. Water samples were collected with Niskin bottles and the total absorption spectra of the seawater was measured. Particulates were removed from the seawater samples by filtration and the filtrate absorption spectra were measured. Subtracting the filtrate absorption from the total seawater absorption yields the absorption spectra for the particulate matter. Subtracting the absorption spectra of pure water from the filtrate absorption results in the absorption spectra for the dissolved organic matter.

R. M. Pope, "Optical absorption of pure water and sea water using the integrating cavity absorption meter," Texas A&M University (1993).