Characterization and qualitative changes in DOM chemical characteristics related to hydrologic conditions in a Pampean stream

MESSETTA, MARÍA LAURA; HEGOBURU, CECILIA; CASAS-RUIZ, JOAN PERE; BUTTURINI, ANDREA; FEIJOÓ, CLAUDIA

HYDROBIOLOGIA

SPRINGER

Lugar: Berlin; Año: 2018 vol. 808 p. 201 - 217

0018-8158

The aim of our study was; (i) to characterizethe composition of DOM in stream water andtheir potential sources (groundwater, overland flow,subsurface flow and rain water) and (ii) to analyzechanges in DOM concentration and compositionunder different hydrological conditions (baseflowand high flow) in a third-order Pampean stream(Argentina). Pampean streams are mainly fed by theshallow aquifer under baseflow conditions and theylack of riparian forest. In addition, water velocity islow due to the gentle slope of the region and nutrientlevels are high, favoring the development of richmacrophyte communities. DOM optical properties inthe stream and end members were determined bycombining absorbance-fluorescence spectroscopytechniques. Our results indicated that DOM chemicalcharacteristics in the stream were mainly modulatedby a differential contribution of end members tostream water depending on hydrological conditions.We observed that DOM in groundwater showed amicrobial origin while DOM in runoff was terrestrially-derived. DOC concentration and inputs of humicsubstances from the riparian zone increased withdischarge at high flow conditions. Due to the stronglink between DOC properties and the riparian environment,structural alterations in the stream channeland changes in riparian vegetation (forestation) mayresult in changes in DOM composition and dynamics.