2 research outputs found
Hydrological transitions drive dissolved organic matter quantity and composition in a temporary Mediterranean stream
18 páginas, 7 figuras, 1 tablaThe implications of stream flow intermittency
for dissolved organic matter (DOM) are not well
understood despite its potential significance for water
quality and ecosystem integrity. We combined intensive
sampling with liquid chromatography and spectroscopic
techniques to follow changes in DOC and DON concentrations
as well as in DOM size fractions and spectroscopic
properties in a temporary stream during an entire
contraction–fragmentation–expansion hydrological cycle.
DOC and DON concentrations remained low
(range = 1.4–5.2 mg C L-1 and 0.05–0.15 mg N L-1)
during hydrological contraction and fragmentation, with
concomitant increases in the proportion of high molecularweight
substances (HMWS)during contraction and
of DOM aromaticity during fragmentation. DOC and
DON concentrations abruptly increased (up to
8.8 mg C L-1 and 0.37 mg N L-1) at the end of the
fragmentation phase, with a concomitant increase in the
non-humic, microbial and aquatic character of DOM.
Upon rewetting, the DOC and DON concentrations
reached their highest values (up to 12.7 mg C L-1 and
0.39 mg N L-1), with concomitant increases in the
proportion of HMWS and in the humic, aromatic and
terrestrial character of DOM. Subsequently, DOC and
DON concentrations recovered to values similar to those
at the contraction phase, while DOM composition
variables indicated the prevalence of a DOM of humic
and terrestrial character during the whole expansion
phase. Overall, our results emphasize the importance of
hydrological transitions forDOMdynamics in temporary
streams, and point to the potential response of perennial
streams under future water scarcity scenarios.This studywas funded by theEuropean
Union through the MIRAGE project (FP7 ENV 2007 1).
Additional funds were provided by the Spanish Ministry of
Economy and Competitiveness through the Consolider-Ingenio
projects SCARCE (CSD2009-00065) and GRACCIE (CSD2007-
00067). D. von Schiller was supported by a DAAD-‘‘laCaixa’’
fellowship and a ‘‘Juan de la Cierva’’ postdoctoral grant (JCI-
2010-06397).Peer reviewe