Light absorption by aquatic particles in the near‐infrared spectral region

In this study, we used a special measurement geometry with samples placed inside the integrating sphere to address whether significant absorption by aquatic particles exists in the near‐infrared (near‐IR) spectral region from about 700 to 850 nm. Our tests with inorganic dyes and MgCO3 particles showed that placing a small sample (1 cm cuvette) inside a relatively large integrating sphere (15 cm diameter) reduced the scattering error to a negligible level with no adverse effect on the absorption measurement. Our measurements of absorption by various particle suspensions suggest that absorption is generally negligible in the near‐IR regardless of the type of particles. We examined four species of phytoplankton, phytodetritus derived from phytoplankton cultures, three samples of natural assemblages of mineral particles that show distinct reddish or brownish color, and three samples of aquatic particles from coastal and inland waters that have varying proportions of organic and inorganic particles.

[1]  R. Bukata,et al.  Estimation of Organic and Inorganic Matter in Inland Waters: Optical Cross Sections of Lakes Ontario and Ladoga , 1991 .

[2]  D. Bowers,et al.  Absorption spectra of inorganic particles in the Irish Sea and their relevance to remote sensing of chlorophyll , 1996 .

[3]  B. Osborne,et al.  Light and Photosynthesis in Aquatic Ecosystems. , 1985 .

[4]  B. G. Mitchell,et al.  Algorithms for determining the absorption coefficient for aquatic particulates using the quantitative filter technique , 1990, Defense, Security, and Sensing.

[5]  C. Whittingham,et al.  Photosynthesis , 1941, Nature.

[6]  Dariusz Stramski,et al.  Variations in the light absorption coefficients of phytoplankton, nonalgal particles, and dissolved organic matter in coastal waters around Europe , 2003 .

[7]  A. Bricaud,et al.  Spectral absorption coefficients of living phytoplankton and nonalgal biogenous matter: A comparison between the Peru upwelling areaand the Sargasso Sea , 1990 .

[8]  R. Olson,et al.  Prochlorococcus marinus nov. gen. nov. sp.: an oxyphototrophic marine prokaryote containing divinyl chlorophyll a and b , 1992, Archives of Microbiology.

[9]  Norman B. Nelson,et al.  Calibration of an integrating sphere for determining the absorption coefficient of scattering suspensions. , 1993, Applied optics.

[10]  M. Perry,et al.  Modeling in situ phytoplankton absorption from total absorption spectra in productive inland marine waters , 1989 .

[11]  Stelvio Tassan,et al.  An alternative approach to absorption measurements of aquatic particles retained on filters , 1995 .

[12]  C. Yentsch.  MEASUREMENT OF VISIBLE LIGHT ABSORPTION BY PARTICULATE MATTER IN THE OCEAN1 , 1962 .

[13]  James C. Kitchen,et al.  Reflective-tube absorption meter , 1990, Defense, Security, and Sensing.

[14]  J. Węsławski,et al.  Estimation of glacial meltwater discharge into Svalbard coastal waters , 1997 .

[15]  R. Chester,et al.  Rain water-aerosol trace metal relationships at cap ferrat: A coastal site in the Western Mediterranean , 1997 .

[16]  L. Prieur,et al.  An optical classification of coastal and oceanic waters based on the specific spectral absorption curves of phytoplankton pigments, dissolved organic matter, and other particulate materials1 , 1981 .

[17]  Annick Bricaud,et al.  Optical efficiency factors of some phytoplankters1 , 1983 .

[18]  James R. Nelson,et al.  Detrital spectral absorption: laboratory studies of visible light effects on phytodetritus absorption, bacterial spectral signal, and comparison to field measurements , 1993 .