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Title: Effects of aluminum-induced aggregation on the fluorescence of humic substances

Abstract

Aluminum-induced aggregates of terrestrial and aquatic humic acid standards from the International Humic Substances Society are shown to be fluorescent by means of a multiwavelength fluorescence anisotropy experiment in which the data were treated with a model for nonspherical particles. While aggregates of aquatic humic acids appear in the fluorescence signal at both short and long excitation wavelengths, aggregates of terrestrial humic acids are detected only at the long Wavelength. Furthermore, the results indicate that emission obtained at longer excitation wavelengths is representative of smaller particles. At pH 4, the aquatic humic acids appear to exist in an extended conformation, whereas the terrestrial humic acids show less extension. The size and shape of the fluorescent particles display a complex dependence on Al concentration. Both enhancement and quenching of fluorescence are observed in the total luminescence spectra upon Al addition. However, quenching is shown to be the result of decreased humic acid concentration due to precipitation by Al rather than photophysical processes.

Authors:
;  [1]
  1. Duke Univ., Durham, NC (United States). Dept. of Chemistry
Publication Date:
OSTI Identifier:
687362
Resource Type:
Journal Article
Journal Name:
Environmental Science and Technology
Additional Journal Information:
Journal Volume: 33; Journal Issue: 18; Other Information: PBD: 15 Sep 1999
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; HUMIC ACIDS; ALUMINIUM; FLUORESCENCE; AGGLOMERATION; MATHEMATICAL MODELS; SOIL CHEMISTRY; WATER CHEMISTRY

Citation Formats

Sharpless, C.M., and McGown, L.B. Effects of aluminum-induced aggregation on the fluorescence of humic substances. United States: N. p., 1999. Web. doi:10.1021/es981332v.
Sharpless, C.M., & McGown, L.B. Effects of aluminum-induced aggregation on the fluorescence of humic substances. United States. doi:10.1021/es981332v.
Sharpless, C.M., and McGown, L.B. Wed . "Effects of aluminum-induced aggregation on the fluorescence of humic substances". United States. doi:10.1021/es981332v.
@article{osti_687362,
title = {Effects of aluminum-induced aggregation on the fluorescence of humic substances},
author = {Sharpless, C.M. and McGown, L.B.},
abstractNote = {Aluminum-induced aggregates of terrestrial and aquatic humic acid standards from the International Humic Substances Society are shown to be fluorescent by means of a multiwavelength fluorescence anisotropy experiment in which the data were treated with a model for nonspherical particles. While aggregates of aquatic humic acids appear in the fluorescence signal at both short and long excitation wavelengths, aggregates of terrestrial humic acids are detected only at the long Wavelength. Furthermore, the results indicate that emission obtained at longer excitation wavelengths is representative of smaller particles. At pH 4, the aquatic humic acids appear to exist in an extended conformation, whereas the terrestrial humic acids show less extension. The size and shape of the fluorescent particles display a complex dependence on Al concentration. Both enhancement and quenching of fluorescence are observed in the total luminescence spectra upon Al addition. However, quenching is shown to be the result of decreased humic acid concentration due to precipitation by Al rather than photophysical processes.},
doi = {10.1021/es981332v},
journal = {Environmental Science and Technology},
number = 18,
volume = 33,
place = {United States},
year = {1999},
month = {9}
}