caa a22 4500 605516766 CHVBK 20210128100716.0 cr unu---uuuuu 210128e20150101xx s 000 0 eng 10.1007/s10533-014-0035-6 doi (NATIONALLICENCE)springer-10.1007/s10533-014-0035-6 Spatiotemporal variations in carbon dynamics during a low flow period in a carbonate karst watershed: Santa Fe River, Florida, USA [Elektronische Daten] [Jin Jin, Andrew Zimmerman, Jonathan Martin, Mitra Khadka] To understand role of biogeochemical reactions in controlling the amount and molecular form of dissolved carbon exported from carbonate terrains, spatiotemporal variations in dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) were observed over one year in the Santa Fe River system, a period of base flow or below. A water mixing model developed using concentrations of Na+, Cl−, and SO 4 −2 identified three major water sources: soil water, groundwater and deep aquifer water. After accounting for mixing of these water sources, additional chemical signatures resulting from biogeochemical processes in the riparian zone were identified. Net mineralization of DOC occurred throughout the Santa Fe River watershed, particularly during the lowest flow conditions and in the upper watershed. However, natural dissolved organic matter was more labile during low flow and in the lower watershed, and predominantly derived from groundwater (rather than soil water) in all samples, likely via releases during carbonate dissolution. Carbonate dissolution commonly occurred in the upper watershed during low flow conditions, while carbonate minerals precipitated during baseflow, as well as in the lower watershed during very low flow conditions. Thus, riparian zone biogeochemical processes were strongly mediated by watershed hydrology, whose spatiotemporal variations resulted in greater inorganic and organic C export production in the lower watershed than the upper watershed, and during higher flow versus lower flow periods. During this lower flow period, the Santa Fe River watershed exported~1.0 and 10.3tonkm−2year−1 DOC and DIC, respectively, representing higher C yields than many other types of watersheds. Springer International Publishing Switzerland, 2014 Dissolved organic carbon nationallicence Dissolved inorganic carbon nationallicence Biogeochemical processes nationallicence Hydrologic mixing model nationallicence Carbon cycling nationallicence Karst nationallicence Jin Jin Department of Geological Sciences, University of Florida, 241 Williamson Hall, P.O. Box 112120, 32611, Gainesville, FL, USA aut Zimmerman Andrew Department of Geological Sciences, University of Florida, 241 Williamson Hall, P.O. Box 112120, 32611, Gainesville, FL, USA aut Martin Jonathan Department of Geological Sciences, University of Florida, 241 Williamson Hall, P.O. Box 112120, 32611, Gainesville, FL, USA aut Khadka Mitra Department of Geological Sciences, University of Florida, 241 Williamson Hall, P.O. Box 112120, 32611, Gainesville, FL, USA aut Biogeochemistry Springer International Publishing 122/1(2015-01-01), 131-150 0168-2563 122:1<131 2015 122 10533 https://doi.org/10.1007/s10533-014-0035-6 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s10533-014-0035-6 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Jin Jin Department of Geological Sciences, University of Florida, 241 Williamson Hall, P.O. Box 112120, 32611, Gainesville, FL, USA aut NATIONALLICENCE 700 1- Zimmerman Andrew Department of Geological Sciences, University of Florida, 241 Williamson Hall, P.O. Box 112120, 32611, Gainesville, FL, USA aut NATIONALLICENCE 700 1- Martin Jonathan Department of Geological Sciences, University of Florida, 241 Williamson Hall, P.O. Box 112120, 32611, Gainesville, FL, USA aut NATIONALLICENCE 700 1- Khadka Mitra Department of Geological Sciences, University of Florida, 241 Williamson Hall, P.O. Box 112120, 32611, Gainesville, FL, USA aut NATIONALLICENCE 773 0- Biogeochemistry Springer International Publishing 122/1(2015-01-01), 131-150 0168-2563 122:1<131 2015 122 10533