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Natural photolysis by ultraviolet irradiance of recalcitrant dissolved organic matter to simple substrates for rapidbacterial metabolism
Author(s) -
Wetzel Robert G.,
Hatcher Patrick G.,
Bianchi Thomas S.
Publication year - 1995
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1995.40.8.1369
Subject(s) - chemistry , dissolved organic carbon , environmental chemistry , photodissociation , formic acid , organic matter , chromatography , photochemistry , organic chemistry
Whole leachate and humic and fulvic acid fractions of dissolved organic matter (DOM) released from senescent littoral aquatic plants were exposed to varying spectra of ultraviolet radiation as well as natural UV of sunlight over different periods of time. Examination of the DOM by solid‐state 13 C nuclear magnetic resonance and pyrolytic gas chromatography‐mass spectrometry before and after photolysis revealed only subtle changes to the bulk DOM. However, the DOM exposed to natural UV radiation showed immediate stimulation of and sustained bacterial growth. Chemical analyses by high performance liquid chromatography (HPLC) of the small organic fractions generated by photolysis of humic substances showed marked, progressively increasing release of numerous small fatty acids, particularly acetic, formic, citric, pyruvic, and levulinic, among others. Use of radiolabeled humic substances demonstrated that these small compounds photolyzed from the humic substances were readily metabolized by the bacteria.