The influence of phytoplankton pigments on the colour of sea water

By summing the absorbency of phytoplankton pigments with that of pure water, the absorption of the blue portion of the spectrum is markedly increased. As the concentration of phytoplankton pigments increases, the diminution of blue light gradually shifts the wave length of maximum transmission toward the green. At the concentration of phytoplankton pigments normally found in the open ocean, the red chlorophyll band has little influence on water colour.

Inadequancies in present methods for detection of absorption bands in natural waters is attributed to wide band widths of filters used in submarine photometers. Poor spectral curves applicable to colour analysis in particulate systems are obtained by conventional spectrophotometric techniques because a large portion of the scattered light never reaches the photo-detector. Improvements for spectral analysis are suggested.