title: Groundwater drift as a tracer for identifying sources of spring discharge.
abstract: Groundwater invertebrate drift, collected from the spring outlets at the interface of vadose and phreatic zones, has been examined for its potential for identifying sources of discharge from a karst aquifer. Concurrently, major ion geochemistry, dissolved inorganic carbon (δ13CDIC), particulate organic carbon (δ13CPOC), and naturally occurring stable isotopes of oxygen and tritium (δ18O, 3H) were investigated over a period of 1 year in two outlets, a temporary (TS) and a perennial (PS) spring. A few differences in major ion geochemistry and stable isotope composition were found between the two springs together with moderate seasonal variability. In contrast, invertebrate drift showed clear differences between TS and PS springs in density and composition. Canonical correspondence analysis showed the presence of two distinct groups of samples from TS and PS, with Ca2+ as the only significant explanatory variable for differences in drift composition. Finally, certain species from the drift were found to be useful tracers for distinguishing between the phreatic and the epikarst and vadose zones as the origin of spring water.
authors.affiliation: Department of Environmental Science, Jožef Stefan Institute, Jamova cesta 39, Ljubljana 1000, Slovenia.
authors.forename: Nataša
authors.initials: N
authors.lastname: Mori
authors.forename: Tjaša
authors.initials: T
authors.lastname: Kanduč
authors.forename: Maja
authors.initials: M
authors.lastname: Opalički Slabe
authors.forename: Anton
authors.initials: A
authors.lastname: Brancelj
mesh_terms: D000818:Animals; D002118:Calcium / Q000032:analysis; D002247:Carbon Isotopes / Q000032:analysis; D003445:Crustacea; D004784:Environmental Monitoring / Q000379:methods*; D060587:Groundwater / Q000032:analysis*; D060985:Natural Springs / Q000032:analysis*; D010103:Oxygen Isotopes; D017524:Slovenia; D014316:Tritium / Q000032:analysis; D014872:Water Movements
chemical_list: D002247:Carbon Isotopes; D010103:Oxygen Isotopes; D014316:Tritium; D002118:Calcium