Triplicate samples were collected from three lakes in order to study variation in the specific absorption of dissolved organic carbon (DOC). Specific absorption was highly correlated with lake pH and DOC concentration, with the DOC in acid lakes absorbing less light at all wavelengths. The slope of the specific absorption curves did not seem to be significantly different in acid and non-acid lakes. This suggests that the decrease in specific absorption as pH declines is not due to change in the fulvic acid fraction, but to changes in the molecules themselves. Sampling variance is reasonably consistent across the range of lakes examined. Thus it may be possible to use an average variance to assign confidence limits when single samples are collected.
E.A. Gallie, E.A. Gallie,
"Variation in the specific absorption of dissolved organic carbon in northern Ontario lakes", Proc. SPIE 2963, Ocean Optics XIII, (6 February 1997); doi: 10.1117/12.266477; https://doi.org/10.1117/12.266477