Publication: Dry phase conditions prime wet‐phase dissolved organic matter dynamics in intermittent rivers
Authors
Campo, Rubén del ; Gómez Cerezo, Rosa María ; Singer, Gabriel
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Publisher
Wiley Periodicals, Inc.
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DOI
https://doi.org/10.1002/lno.11163
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info:eu-repo/semantics/article
Description
©2019. This manuscript version is made available under the CC-BY-NC 4.0 license http://creativecommons.org/licenses/by-nc/4.0/.
This document is the Published version of a Published Work that appeared in final form in Limnology and Oceanography. To access the final edited and published work see https://doi.org/10.1002/lno.11163
Abstract
During the dry phase of intermittent rivers, diverse particulate organic materials, such as leaf litter or macrophytes,
remain on dry riverbeds. Together with riverbed sediments, these organic substrates are exposed to various
environmental conditions that can alter their chemical composition, with potential implications for later
use by heterotroph consumers when flow is re-established. Here, we investigate how different environmental
conditions during the dry phase alter quantity, composition, and biodegradability of dissolved organic matter
(DOM) leached from dry riverbeds. To this end, we simulated the “preconditioning” of various DOM sources
during a dry phase of 60 d under conditions mimicking open- and closed-canopy rivers. Over the whole experiment,
we produced leachates for measurements of nutrients and dissolved organic carbon (DOC) concentration,
DOM characterization by absorbance and fluorescence measurements and ultrahigh-resolution mass spectrometry,
and DOM biodegradability. We found that rain, solar radiation, and its associated heat greatly affected
leached DOM quantity, composition, and biodegradability. Under open-canopy conditions, sporadic rain caused
the impoverishment of nutrients and DOC by leaching, whereas intense solar radiation and associated heat
resulted in a drop of DOM quality and biodegradability by accelerated humification of DOM. In contrast, the
preconditioning of DOM sources under a closed canopy barely affected DOM quality and biodegradability
because of the protection from rain, solar radiation, and heat by the forest vegetation. Our results suggest that
contrasting environmental conditions during the dry phase in open- vs. closed-canopy intermittent rivers can
translate into radically different DOM processing during the early wet phase.
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Citation
Limnology and Oceanography, 64, 2019, 1966–1979
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