title: Carbon isotope signature of dissolved inorganic carbon (DIC) in precipitation and atmospheric CO2.
abstract: This paper describes results of chemical and isotopic analysis of inorganic carbon species in the atmosphere and precipitation for the calendar year 2008 in Wrocław (SW Poland). Atmospheric air samples (collected weekly) and rainwater samples (collected after rain episodes) were analysed for CO2 and dissolved inorganic carbon (DIC) concentrations and for δ13C composition. The values obtained varied in the ranges: atmospheric CO2: 337-448 ppm; δ13CCO2 from -14.4 to -8.4‰; DIC in precipitation: 0.6-5.5 mg dm(-3); δ13CDIC from -22.2 to +0.2‰. No statistical correlation was observed between the concentration and δ13C value of atmospheric CO2 and DIC in precipitation. These observations contradict the commonly held assumption that atmospheric CO2 controls the DIC in precipitation. We infer that DIC is generated in ambient air temperatures, but from other sources than the measured atmospheric CO2. The calculated isotopic composition of a hypothetical CO2 source for DIC forming ranges from -31.4 to -11.0‰, showing significant seasonal variations accordingly to changing anthropogenic impact and atmospheric mixing processes.
authors.affiliation: Laboratory of Isotope Geology and Geoecology, Department of Applied Geology and Geochemistry, Institute of Geological Sciences, University of Wroclaw, Cybulskiego Street 30, 50-205 Wroclaw, Poland.
authors.forename: Maciej
authors.initials: M
authors.lastname: Górka
authors.affiliation: Biogeochemical Laboratory, Department of Geological Sciences, Indiana University, USA.
authors.forename: Peter E
authors.initials: PE
authors.lastname: Sauer
authors.affiliation: Laboratory of Isotope Geology and Geoecology, Department of Applied Geology and Geochemistry, Institute of Geological Sciences, University of Wroclaw, Cybulskiego Street 30, 50-205 Wroclaw, Poland. Electronic address: dominika.lewicka@ing.uni.wroc.pl.
authors.forename: Dominika
authors.initials: D
authors.lastname: Lewicka-Szczebak
authors.affiliation: Laboratory of Isotope Geology and Geoecology, Department of Applied Geology and Geochemistry, Institute of Geological Sciences, University of Wroclaw, Cybulskiego Street 30, 50-205 Wroclaw, Poland.
authors.forename: Mariusz-Orion
authors.initials: MO
authors.lastname: Jędrysek
mesh_terms: D002244:Carbon / Q000032:analysis* / Q000737:chemistry; D002245:Carbon Dioxide / Q000032:analysis* / Q000737:chemistry; D002247:Carbon Isotopes / Q000032:analysis* / Q000737:chemistry; D011891:Rain / Q000737:chemistry
chemical_list: D002247:Carbon Isotopes; D002245:Carbon Dioxide; D002244:Carbon