| Title | Quality and reactivity of dissolved organic matter in a Mediterranean river across hydrological and spatial gradients |
| Abstract | Understanding DOM transport and reactivity in rivers is essential to having a complete picture of the global carbon
cycle. In this study,we explore the effects of hydrological variability and downstreamtransport on dissolved
organic matter (DOM) dynamics in a Mediterranean river. We sampled the main stem of the river Tordera from
the source to the sea, over a range of fifteen hydrological conditions including extreme events (flood and
drought). By exploring spatial and temporal gradients of DOM fluorescence properties, river hydrology was
found to be a significant predictor of DOMspatial heterogeneity. An additional space-resolved mass balance analysis
performed on four contrasting hydrological conditions revealed that this was due to a shift in the biogeochemical
function of the river. Flood conditions caused a conservative transport of DOM, generating a
homogeneous, humic-like spatial profile ofDOMquality. Lower flows induced a non-conservative, reactive transport
ofDOM,which enhanced the spatial heterogeneity of DOMproperties.Moreover, the downstreamevolution
of DOMchemostatic behaviour revealed that the role of hydrology in regulating DOMproperties increased gradually
downstream, indicating an organised inter-dependency between the spatial and the temporal dimensions.
Overall, our findings reveal that riverine DOMdynamics is in constant change owing to varying hydrological conditions,
and emphasize that in order to fully understand the role of rivers in the global carbon cycle, it is necessary
to take into account the full range of hydrological variability, from floods to droughts. |
| Source | Science of the total environment 599-600 (2017) (1802-1812) |
| Keywords | Mediterranean RiversOrganc Matter |
| Journal | Science of the total environment |
| Editor | Elsevier, Lausanne ;, Paesi Bassi |
| Year | 2017 |
| Type | Articolo in rivista |
| DOI | 10.1016/j.scitotenv.2017.05.113 |
| Authors | Ejarque E., A. Freixa, E. Vazquez, A. Guarch, S. Amalfitano, S. Fazi, A.M. Romaní, A. Butturini, |
| Text | 372323 2017 10.1016/j.scitotenv.2017.05.113 ISI Web of Science WOS WOS 000405253500074 Scopus 2 s2.0 85019379071 Mediterranean Rivers Organc Matter Quality and reactivity of dissolved organic matter in a Mediterranean river across hydrological and spatial gradients Ejarque E., A. Freixa, E. Vazquez, A. Guarch, S. Amalfitano, S. Fazi, A.M. Romani, A. Butturini, WasserCluster Lunz Biologische Station, Lunz am See, Austria b Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Barcelona, Spain c Catalan Institute for Water Research ICRA , Girona, Spain d Water Research Institute, National Research Council of Italy IRSA CNR , Rome, Italy e GRECO, Institute of Aquatic Ecology, Department of Environmental Sciences, University of Girona, Girona, Spain Understanding DOM transport and reactivity in rivers is essential to having a complete picture of the global carbon cycle. In this study,we explore the effects of hydrological variability and downstreamtransport on dissolved organic matter DOM dynamics in a Mediterranean river. We sampled the main stem of the river Tordera from the source to the sea, over a range of fifteen hydrological conditions including extreme events flood and drought . By exploring spatial and temporal gradients of DOM fluorescence properties, river hydrology was found to be a significant predictor of DOMspatial heterogeneity. An additional space resolved mass balance analysis performed on four contrasting hydrological conditions revealed that this was due to a shift in the biogeochemical function of the river. Flood conditions caused a conservative transport of DOM, generating a homogeneous, humic like spatial profile ofDOMquality. Lower flows induced a non conservative, reactive transport ofDOM,which enhanced the spatial heterogeneity of DOMproperties.Moreover, the downstreamevolution of DOMchemostatic behaviour revealed that the role of hydrology in regulating DOMproperties increased gradually downstream, indicating an organised inter dependency between the spatial and the temporal dimensions. Overall, our findings reveal that riverine DOMdynamics is in constant change owing to varying hydrological conditions, and emphasize that in order to fully understand the role of rivers in the global carbon cycle, it is necessary to take into account the full range of hydrological variability, from floods to droughts. 599 600 2017 Published version http //www.scopus.com/inward/record.url eid=2 s2.0 85019379071 partnerID=MN8TOARS Quality and reactivity of dissolved organic matter in a Mediterranean river across hydrological and spatial gradients Ejarque ey al 2017 STOTEN.pdf Articolo in rivista Elsevier 0048 9697 Science of the total environment Science of the total environment Sci. total environ. stefano.fazi FAZI STEFANO stefano.amalfitano AMALFITANO STEFANO |
