title: Impacts of rainfall events on runoff water quality in an agricultural environment in temperate areas.
abstract: Since a rise in dissolved organic carbon (DOC) concentrations has been observed for surface waters at least over the last two decades, a change in weather conditions (temperature and precipitations) has been proposed to partly explain this increase. While the majority of DOC delivery from soils to stream occurs during rainfall events, a better understanding of the rainfall influence on DOC release is needed. This study has been conducted in Brittany, western France, on agricultural experimental plots receiving either cattle manure (CM) or pig slurry (PS) as fertilizers in accordance with local practices. Each plot was instrumented with a flow meter and an auto sampler for runoff measurements. The results show that export of DOC during high intensity events is higher than during lower intensity rainfalls. Fertilization has a noticeable impact on total organic carbon (TOC) fluxes with an increase of five to seven folds for PS and CM respectively. If TOC shock load occurs shortly after the rainfall peak, DOC maximum appears with the first flush of the event. Organic carbon (OC) is mainly under colloidal (41.2%) and soluble (23.9%) forms during the first stage of a rainfall event and a control of rainfall intensity on OC colloidal transport is suggested. These findings highlight the potential risk of receiving water quality degradation due to the increase of heavier rainfall events with climate change in temperate areas.
authors.affiliation: Environment and Health Research Laboratory, School of Advanced Studies in Public Health, 35043 Rennes, France.
authors.forename: Ianis
authors.initials: I
authors.lastname: Delpla
authors.forename: Estelle
authors.initials: E
authors.lastname: Baurès
authors.forename: Aude-Valérie
authors.initials: AV
authors.lastname: Jung
authors.forename: Olivier
authors.initials: O
authors.lastname: Thomas
mesh_terms: D000383:Agriculture; D002244:Carbon / Q000032:analysis; D002980:Climate; D004784:Environmental Monitoring; D005602:France; D005618:Fresh Water / Q000737:chemistry; D011891:Rain; D014874:Water Pollutants, Chemical / Q000032:analysis; D014876:Water Pollution / Q000032:analysis / Q000706:statistics & numerical data*
chemical_list: D014874:Water Pollutants, Chemical; D002244:Carbon