Effects of aqueous chemistry on the binding of polycyclic aromatic hydrocarbons by dissolved humic materials

Journal Article · Sat May 01 00:00:00 EDT 1993 · Environmental Science and Technology; (United States)

DOI:https://doi.org/10.1021/es00042a020· OSTI ID:5815938

Schlautman, M A; Morgan, J J ^[1]

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1. California Inst. of Technology, Pasadena (United States)

The influence of solution chemistry on the binding of three polycyclic aromatic hydrocarbons (PAHs) by well-characterized humic material (Suwannee River humic and fulvic acid) was examined by using fluorescence quenching techniques. The experiments show that binding is complete within 3 min and that the fluorescence of PAH compounds associated with the humic substances is fully quenched as evidenced by quantum yields which approached zero for all systems. These observations validate the use of fluorescence quenching in determining partition coefficients. In NaCl solutions, the binding of PAHs by Suwannee River humic material generally decreased with increases in pH (constant ionic strength) and generally decreased with increasing ionic strength (fixed pH). The presence of Ca[sup 2+] yielded mixed results: at neutral to high pH values, it generally increased the binding of PAHs relative to that in NaCl solutions, while at low pH it generally had little effect on the binding. From the results of this study, it is hypothesized that the binding of a particular PAH compound by Suwannee River humic substances depends not only on the hydrophobicity of the PAH solute but also on the size of the solute molecule and its ability to fit into hydrophobic cavities in humic and fulvic material. This hypothesis is supported by the experimental observations above, as well as the failure of a Flory-Huggins partitioning (i.e., dissolution) model to consistently characterize the hydrophobic environment of the humic substances. 47 refs., 6 figs., 3 tabs.

• OSTI ID: 5815938
• Journal Information: Environmental Science and Technology; (United States), Journal Name: Environmental Science and Technology; (United States) Vol. 27:5; ISSN ESTHAG; ISSN 0013-936X
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102 -- Chemical & Spectral Procedures
400500 -- Photochemistry
54 ENVIRONMENTAL SCIENCES
540320* -- Environment
Aquatic-- Chemicals Monitoring & Transport-- (1990-)
ALKALI METAL COMPOUNDS
AMINES
ANTHRACENE
AROMATICS
CALCIUM IONS
CARBOXYLIC ACIDS
CHARGED PARTICLES
CHLORIDES
CHLORINE COMPOUNDS
CONDENSED AROMATICS
DATA
DISPERSIONS
DYES
EXPERIMENTAL DATA
FLUORESCENCE
HALIDES
HALOGEN COMPOUNDS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HUMUS
HYDROCARBONS
INFORMATION
IONS
LUMINESCENCE
MIXTURES
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PERYLENE
PH VALUE
POLLUTION
POLYCYCLIC AROMATIC HYDROCARBONS
PYRENE
REAGENTS
RHODAMINES
SODIUM CHLORIDES
SODIUM COMPOUNDS
SOLUTIONS
WATER POLLUTION