Delta13C of organic atmospheric dust deposited in Wrocław (SW Poland): critical remarks on the passive method

This paper reports the results of the application of passive collectors to the collection of solid organic atmospheric particles (SOAP) in Wrocław (SW Poland) to carry out stable carbon isotope analyses. delta exp.13C (SOAP) values collected during the vegetation-free period, from November to March, vary in a narrow range from -24.5 to -27.8‰. We show that d13C (SOAP) is able to provide information about atmospheric pollution with respect to different emission sources. delta exp.13C (SOAP) values collected during the period of vegetation growth, from April to October, show a wide range from -20.5 to -26.9‰. The most probable explanations for the 13C- enriched values in summer are that: (i) the SOAP have been contaminated with fresh and decomposed organic matter in the passive collector and/or (ii) SOAP are derived from out side the city or from out side Poland (C4 plant particles). There fore, the d13C (SOAP) may not represent a strictly anthropogenic im pact. The passive collector method for the (SOAP) collection should be applied only in areas with dry deposition of atmospheric dust where deposited organic matter is not de composed in the water contained in collectors. We recommend the use of active sampling methods (hi-volume sampler) to collect SOAP use ful for carbon isotope analyses.