| Title | Dissolved organic matter composition in a fragmented Mediterranean fluvial system under severe drought conditions |
| Abstract | Abstract In Mediterranean regions, drought is one of
the main factors shaping fluvial ecosystems. Droughts
cause a shift from lotic to lentic conditions, triggering a
gradual fragmentation of the longitudinal hydrological
continuum, and a severe alteration of water chemical
properties. However, within a biogeochemical perspective,
little is known about how and to which extend
droughts modify the chemical properties of dissolved
organic matter (DOM). In this study, the variability of
DOM properties along a fragmented fluvial system is
explored, during a summer severe drought, by means of
(a) the ratio between dissolved organic carbon and
nitrogen concentrations (DOC:DON); (b) DOC bioavailability
(BDOC) and (c) DOM optical properties
(SUVA index, fluorescence index, and excitation-
emission fluorescence matrices). DOM and water
measurements were collected from isolated water
parcels that became disconnected from the fluvial
continuum at different times, and were compared with
data obtained in the following autumn, when the fluvial
continuum was re-established. Analysis of DOM
chemical properties evidenced that these properties
during drought clearly differed from those observed in
autumn, but changes did not follow an arbitrary pattern.
Thus, the sampling sites with lotic water bodies showed
DOM properties similar to those observed in autumn
reflecting the dominance of terrestrial inputs. But, once
hydrological fragmentation occurred, there was a gradual
increase in the contribution of autochthonous DOM
as the time elapsed since the poolswere established, and
the geochemical conditions shifted from oxidized
to reduced conditions. In consequence, the fragmentation
of fluvial continuum generates a set of distinct
biochemical hot spots (i.e., each water parcel),
revealing that extreme drought greatly amplifies the
qualitative heterogeneity of organicmatter in a fluvial
system. |
| Source | Biogeochemistry (Dordrecht) 102, pp. 59–72 |
| Journal | Biogeochemistry (Dordrecht) |
| Editor | Nijhoff/Junk, Boston, Paesi Bassi |
| Year | 2011 |
| Type | Articolo in rivista |
| Authors | Vasquez E., Amalfitano S., Fazi A., Butturini A. |
| Text | 42436 2011 Dissolved organic matter composition in a fragmented Mediterranean fluvial system under severe drought conditions Vasquez E., Amalfitano S., Fazi A., Butturini A. Departament d Ecologia, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain Istituto di Ricerca sulle Acque IRSA CNR , Area della Ricerca Roma 1 , Via Salaria km 29,300, CP1000016 Monterotondo, Rome, Italy Abstract In Mediterranean regions, drought is one of the main factors shaping fluvial ecosystems. Droughts cause a shift from lotic to lentic conditions, triggering a gradual fragmentation of the longitudinal hydrological continuum, and a severe alteration of water chemical properties. However, within a biogeochemical perspective, little is known about how and to which extend droughts modify the chemical properties of dissolved organic matter DOM . In this study, the variability of DOM properties along a fragmented fluvial system is explored, during a summer severe drought, by means of a the ratio between dissolved organic carbon and nitrogen concentrations DOC DON ; b DOC bioavailability BDOC and c DOM optical properties SUVA index, fluorescence index, and excitation emission fluorescence matrices . DOM and water measurements were collected from isolated water parcels that became disconnected from the fluvial continuum at different times, and were compared with data obtained in the following autumn, when the fluvial continuum was re established. Analysis of DOM chemical properties evidenced that these properties during drought clearly differed from those observed in autumn, but changes did not follow an arbitrary pattern. Thus, the sampling sites with lotic water bodies showed DOM properties similar to those observed in autumn reflecting the dominance of terrestrial inputs. But, once hydrological fragmentation occurred, there was a gradual increase in the contribution of autochthonous DOM as the time elapsed since the poolswere established, and the geochemical conditions shifted from oxidized to reduced conditions. In consequence, the fragmentation of fluvial continuum generates a set of distinct biochemical hot spots i.e., each water parcel , revealing that extreme drought greatly amplifies the qualitative heterogeneity of organicmatter in a fluvial system. 102 Vazquez et al 2011 Vazquez_2011_pagine.pdf Articolo in rivista Nijhoff/Junk 0168 2563 Biogeochemistry Dordrecht Biogeochemistry Dordrecht Biogeochemistry Dordrecht Biogeochemistry. Dordrecht stefano.fazi FAZI STEFANO stefano.amalfitano AMALFITANO STEFANO TA.P04.032.002 Ruolo delle comunita microbiche nei cicli biogeochimici e nella degradazione degli inquinanti |
