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Direct and Indirect Effects of Dissolved Organic Matter Source and Concentration on Denitrification in Northern Florida Rivers

dc.contributor.author Fork, ML
dc.contributor.author Heffernan, JB
dc.date.accessioned 2014-09-15T13:51:25Z
dc.date.issued 2014-01-01
dc.identifier.issn 1432-9840
dc.identifier.uri http://hdl.handle.net/10161/9142
dc.description.abstract Using a natural gradient of dissolved organic carbon (DOC) source and concentration in rivers of northern Florida, we investigated how terrestrially-derived DOC affects denitrification rates in river sediments. Specifically, we examined if the higher concentrations of DOC in blackwater rivers stimulate denitrification, or whether such terrestrially-derived DOC supports lower denitrification rates because (1) it is less labile than DOC from aquatic primary production; whether (2) terrestrial DOC directly inhibits denitrification via biochemical mechanisms; and/or whether (3) terrestrial DOC indirectly inhibits denitrification via reduced light availability to-and thus DOC exudation by-aquatic primary producers. We differentiated among these mechanisms using laboratory denitrification assays that subjected river sediments to factorial amendments of NO3- and dextrose, humic acid dosing, and cross-incubations of sediments and water from different river sources. DOC from terrestrial sources neither depressed nor stimulated denitrification rates, indicating low lability of this DOC but no direct inhibition; humic acid additions similarly did not affect denitrification rates. However, responses to addition of labile C increased with long-term average DOC concentration, which supports the hypothesis that terrestrial DOC indirectly inhibits denitrification via decreased autochthonous production. Observed and future changes in DOC concentration may therefore reduce the ability of inland waterways to remove reactive nitrogen. © 2013 Springer Science+Business Media New York.
dc.relation.ispartof Ecosystems
dc.relation.isversionof 10.1007/s10021-013-9705-9
dc.title Direct and Indirect Effects of Dissolved Organic Matter Source and Concentration on Denitrification in Northern Florida Rivers
dc.type Journal article
pubs.begin-page 14
pubs.end-page 28
pubs.issue 1
pubs.organisational-group Duke
pubs.organisational-group Environmental Sciences and Policy
pubs.organisational-group Nicholas School of the Environment
pubs.publication-status Published
pubs.volume 17
dc.identifier.eissn 1435-0629


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