Js. Cleveland et Ad. Weidemann, QUANTIFYING ABSORPTION BY AQUATIC PARTICLES - A MULTIPLE-SCATTERING CORRECTION FOR GLASS-FIBER FILTERS, Limnology and oceanography, 38(6), 1993, pp. 1321-1327
Absorption spectra measured for aquatic particles concentrated onto gl
ass-fiber filters require a correction for the increase in pathlength
caused by multiple scattering in the glass-fiber filter. A multiple sc
attering correction was calculated from optical density spectra for 48
phytoplankton cultures of seven species representing a variety of cel
l sizes, pigment groups, and cell-wall types. The relationship between
optical density in suspensions and on filters was not wavelength-depe
ndent. Differences between blank filters were always spectrally neutra
l. Small differences between relationships for single species were inc
onclusive. Given the absence of wavelength-dependent effects, we repor
t a single general quadratic relationship, OD(susp)(lambda) = 0.378 OD
(filt)(lambda) + 0.523 OD(filt)(lambda)2 (r2 = 0.988), for correcting
glass-fiber filter spectra. For independent samples, the average error
in predicting OD(susp)(lambda) with this algorithm at any wavelength
was 2%. Greatest errors were in spectral regions of low absorption. Ab
sorption spectra for particles concentrated onto glass-fiber filters c
an be quantitatively corrected for multiple scattering within this lim
it. Applicability of the algorithm to field samples of varied composit
ion was enhanced by using a large number of spectra and a range of cel
l types in algorithm development.