Fluvic acids

Chromophoric dissolved organic matter organic compounds such as humic and fluvic acids that form from decomposing organic matter, and absorb light at the blue end of the spectrum giving water a yellowish-brownish color at high concentrations. 

D.M. McKnight, E.D. Andrews, R.L. Smith, R. DufFord (1994). Aquatic fluvic acids in algal-rich Antarctic ponds. Limnol. Oceanogr., 39,1972-1979. 

Ruzicka, J. and Marshal, G.D., Sequential injection analysis as a tool for on-line monitoring the sorption of fluvic acid onto modified Vermiculite, Analytica Chimica Acta (1990), 237, 329. 

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