Photodegradation, interaction with iron oxides and bioavailability of dissolved organic matter from forested floodplain sources


Autoria(s): Howitt, Julia A.; Baldwin, Darren S.; Rees, Gavin N.; Hart, Barry T.
Data(s)

01/01/2008

Resumo

Photochemical degradation of dissolved organic matter (DOM) can influence food webs by altering the availability of carbon to microbial communities, and may be particularly important following periods of high DOM input (e.g. flooding of forested floodplains). Iron oxides can facilitate these reactions, but their influence on subsequent organic products is poorly understood. Degradation experiments with billabong (= oxbow lake) water and river red gum (<i>Eucalyptus </i><i>camaldulensis</i>) leaf leachate were conducted to assess the importance of these reactions in floodplain systems. Photochemical degradation of DOM in sunlight-irradiated quartz tubes (with and without amorphous iron oxide) was studied using gas chromatography and UV-visible spectroscopy. Photochemical reactions generated gaseous products and small organic acids. Bioavailability of billabong DOM increased following irradiation, whereas that of leaf leachate was not significantly altered. Fluorescence excitation-emission spectra suggested that the humic component of billabong organic matter was particularly susceptible to degradation, and the source of DOM influenced the changes observed. The addition of amorphous iron oxide increased rates of photochemical degradation of leachate and billabong DOM. The importance of photochemical reactions to aquatic systems will depend on the source of the DOM and its starting bioavailability, whereas inputs of freshly formed iron oxides will accelerate the processes.<br />

Identificador

http://hdl.handle.net/10536/DRO/DU:30017264

Idioma(s)

eng

Publicador

CSIRO Publishing

Relação

http://dro.deakin.edu.au/eserv/DU:30017264/howitt-photodegradation-2008.pdf

http://dx.doi.org/10.1071/MF07225

Direitos

2008, CSIRO

Palavras-Chave #aquatic carbon cycle #excitation-emission matrix (EEM) #humic substances #Murray River
Tipo

Journal Article