Spectral absorption by marine particles of coastal waters of Baja California1

During March 1979 spectral absorptance for the suspended particles of the coastal waters of Baja California was determined by measuring the diffuse transmittance of filters containing the particles with a simply designed spectrophotometer. The absorptance for the upper water of 20 stations varied by over an order of magnitude, but the spectra were generally similar in shape and indicated that phytoplankton pigments were the dominant absorbers. A region of major spectral change was found between 400 and 435 nm, where a shift in maximal absorptance toward shorter wavelengths was correlated with increased concentrations of pheopigments relative to chlorophyll. A multivariate analysis of the data yielded two spectra for the specific absorptance in units of m2·mg pigment−1 of those particles containing chlorophyll and those containing pheopigments. The specific absorptance for chlorophyll‐containing particles is compared with previous measurements in the field and laboratory; the specific absorptance for pheopigment‐containing particles has not been measured before.