Radiocarbon application in environmental science and archaeology in Croatia

Radiocarbon is a cosmogenic radioisotope equally distributed throughout the troposphere and biosphere. This fact enables its most common application—radiocarbon dating. Natural equilibrium of radiocarbon has been disturbed by diverse anthropogenic activities during the last ∼150 years, enabling also the use of 14C in various environmental applications. Here we present three types of studies by using 14C that were performed in the Zagreb Radiocarbon Laboratory. 14C in atmospheric CO2 has been monitored at several sites with various anthropogenic influences and the difference between the clean-air sites, the industrial city and the vicinity of a nuclear power plant has been established. 14C has been applied in geochronology of karst areas, especially in dating of tufa, speleothems and lake sediments, as well as in studies of geochemical carbon cycle. 14C has been used in various archaeological studies, among which the dating of the early Neolithic settlements in Croatia is presented. In these studies 14C was measured by radiometric techniques, i.e., by gas proportional counting and more recently by liquid scintillation counting (LSC). Two sample preparation techniques for LSC measurement were used: benzene synthesis for archaeological dating and other applications that require better precision, and direct absorption of CO2 for monitoring purposes. The presented results show that various studies by using 14C can be successfully performed by the LSC technique, providing a large enough sample (>1 g of carbon).