Loading...
Photochemical and microbial alteration of dissolved organic matter in temperate headwater streams associated with different land use
Chambers, Randolph
Chambers, Randolph
Abstract
Photochemical and microbial transformations of DOM were evaluated in headwater streams draining forested and humanâmodified lands (pasture, cropland, and urban development) by laboratory incubations. Changes in DOC concentrations, DOC isotopic signatures, and DOM fluorescence properties were measured to assess the amounts, sources, ages, and properties of reactive and refractory DOM under the influence of photochemistry and/or bacteria. DOC in streams draining forestâdominated watersheds was more photoreactive than in streams draining mostly humanâmodified watersheds, possibly due to greater contributions of terrestrial plantâderived DOC and lower amounts of prior light exposure in forested streams. Overall, the percentage of photoreactive DOC in stream waters was best predicted by the relative content of terrestrial fluorophores. The bioreactivity of DOC was similar in forested and humanâmodified streams, but variations were correlated with temperature and may be further controlled by the diagenetic status of organic matter. Alterations to DOC isotopes and DOM fluorescence properties during photochemical and microbial incubations were similar between forested and humanâmodified streams and included (1) negligible effects of microbial alteration on DOC isotopes and DOM fluorescence properties, (2) selective removal of 13Câdepleted and 14Câenriched DOC under the combined influence of photochemical and microbial processes, and (3) photochemical alteration of DOM resulting in a preferential loss of terrestrial humic fluorescence components relative to microbial fluorescence components. This study provides a unique comparison of DOC reactivity in a regional group of streams draining forested and humanâmodified watersheds and indicates the importance of land use on the photoreactivity of DOC exported from upstream watersheds.
Description
Date
2013-03-11
Journal Title
Journal ISSN
Volume Title
Publisher
Collections
Download Dataset
Rights Holder
Usage License
Embargo
Research Projects
Organizational Units
Journal Issue
Keywords
Citation
Advisor
Department
Biology
DOI
https://doi.org/10.1002/jgrg.20048