Proton and aluminum binding properties of organic acids in surface waters of the northeastern U.S.

Habibollah Fakhraei, Charles T. Driscoll

Research output: Contribution to journalArticle

25 Scopus citations

Abstract

A variety of mathematical estimators have been used to quantify the degree of protonation of naturally occurring organic acids. These estimators range from monoprotic, diprotic, and triprotic analog models to the discrete and continuous (Gaussian) distributions of a single proton binding-dissociation. Natural water samples from two long-term monitoring programs in the northeastern U.S. were used to quantify proton- and aluminum-binding properties of naturally occurring organic matter. Water chemistry observations were clustered into 0.05 pH intervals (over 3.75-7.35 pH range) and fit to a triprotic analog model. The model optimization indicates that about 5% of dissolved organic carbon participates in ion binding, and organic acids are composed of both strong and weak acids (i.e., pKa1 = 2.54, pKa2 = 6.19, and pKa3 = 7.52 for Adirondack samples). Binding between organic acids and aluminum can substantially influence the acid behavior of dissolved organic matter and the availability of the toxic form of aluminum (i.e., inorganic monomeric aluminum).

Original languageEnglish (US)
Pages (from-to)2939-2947
Number of pages9
JournalEnvironmental Science and Technology
Volume49
Issue number5
DOIs
StatePublished - Mar 3 2015

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry

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