A radiocarbon (14C) activity analysis in the tree rings around Ignalina nuclear power plant (INPP) has been carried out with the aim to test the hypothesis to use 14C tree-ring analysis data as a tool for the reconstruction of gaseous releases from NPP to the environment. The INPP has been in decommissioning state since the end of 2009. Tree-ring samples for 14C analysis were collected 7 yr after final power unit shutdown from the INPP vicinity. The samples from 5 sampling locations were collected, prepared and measured using the Single Stage Accelerator Mass Spectrometer (SSAMS). Data analysis represents observable Ignalina NPP influence by 14C increase up to 15 pMC (percent modern carbon) in tree rings. Good correlations of the 14C concentrations and wind direction were obtained. The main purpose of this article was to match 14C measurement data along with the atmospheric dispersion modeling of emissions in order to retrospectively characterize the emission source.
<p>Excessive automotive engine exhaust emissions of gases and particulate matter (PM) pose a threat to public health and urban air quality. In an effort to reduce automotive emissions modern cars use a variety of engine modifications, catalytic systems and filters which in turn alter the isotope ratio of carbonaceous particles (isotope fractionation effect). Diesel engines are of particular interest due to higher production of particulates (soot) in comparison to gasoline engines [1].</p><p>The aim of this work was to examine particulate matter &#948;<sup>13</sup>C variation in automotive emissions using stable carbon isotope ratio measurements. Emission experiments were performed in dynamometer laboratory using four light passenger vehicles with differing liquid fuels - diesel, diesel with additives, 92 RON and 95 RON. Vehicles were tested with varying engine power and using simulated transient cycles in urban and rural areas. Engine exhaust particulate matter was collected on quartz filters. Later, isotope ratio &#948;<sup>13</sup>C values of fuel and exhaust carbonaceous particulates were measured using IRMS. &#948;<sup>13</sup>C values were then compared and level of isotope fractionation determined.</p><p>The obtained results show particulate matter &#948;<sup>13</sup>C values ranging from -28.8 &#8240; to -27.2 &#8240; during separate driving modes. Isotope fractionation &#916; (particulates-fuel) values varied between 1.8 &#8240; and 3.5 &#8240;. It was determined that &#948;<sup>13</sup>C values of automotive emissions depend on the type of fuel used, applied engine power, driving modes (urban, rural) and can be used to characterize automotive carbonaceous particle emissions.</p><p>&#160;</p><p>[1]&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; M. V. Twigg, &#8220;Progress and future challenges in controlling automotive exhaust gas emissions,&#8221; <em>Appl. Catal. B Environ</em>., 2007.</p>
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