Measurement report: Nitrogen isotopes (<i>?</i><sup>15</sup>N) and first quantification of oxygen isotope anomalies (<i>?</i><sup>17</sup>O, <i>?</i><sup>18</sup>O) in atmospheric nitrogen dioxide

Abstract. The isotopic composition of nitrogen and oxygen in dioxide (NO2) potentially carries a wealth information about the dynamics oxides (NOx = nitric oxide (NO) + NO2) chemistry atmosphere. While isotopes NO2 are subtle indicators NOx emissions chemistry, believed to reflect only O3 / VOC chemical regime different atmospheric environments. In order access this potential tracer tropospheric we have developed an efficient active method trap on denuder tubes measured, for first time, its multi-isotopic (?15N, ?18O, ?17O). ?17O values trapped at our site Grenoble, France, show large diurnal cycle peaking late morning (39.2 ± 0.3) ‰ decreasing night until (20.5 ‰. On top cycle, also exhibits substantial daytime variability (from 29.7 39.2 ‰), certainly driven by changes peroxyl radicals (RO2) ratio. nighttime decay ?17O(NO2) appears be slow removal, mostly from conversion into N2O5, formation reaction between freshly emitted NO. As expected expression, measured towards end is quantitatively consistent with typical ?17O(O3). Daytime N isotope fractionation estimated using general expression linking it ?17O(NO2). An derived fractionation. contrast ?17O(NO2), ?15N(NO2) measurements exhibit little (?11.8 ?4.9 ‰) negligible fractionations NO NO2, mainly due high ratios, excepted during rush hours. main emission sources Bayesian mixing model, indicating predominance traffic area. These preliminary results very promising combination ?15N as probe fate interpreting nitrate records.