Abstract. Measurements of the complete isotopic composition of atmospheric CO ( 13 CO, 14 CO, C 17 O, C 18 O) have been carried out at the high northern latitude stations Spitsbergen, Norway, and Alert, Canada. The annual changes of the isotope signatures reflect the seasonally varying contributions from the individual CO sources and the OH sink. Short-term variability is small at the remote sampling locations. Nevertheless, the interannual variability is considerable, in particular for the summer minimum. The most prominent event was a strong increase in CO in 1998 that persisted for several months. Using the isotope signatures it is possible to clearly identify extraordinarily strong biomass burning during that season as the cause for this large-scale CO anomaly. In 1997, on the other hand, biomass burning emissions were very low, leading to an unusually low summer minimum and corresponding isotope signatures. The results underscore that monitoring of CO and its isotopic composition at remote high latitude stations is a valuable tool to better understand long-term variations of CO that are representative for the whole high northern latitude region.

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Radioactive anthropogenic pollution has raised concerns about the present and future environmental status of the semienclosed Baltic Sea. We here study the distribution and inventory of the anthropogenic radioactive (129)I in water depth profiles collected from 16 sites in August 2006 and 19 sites in April 2007 in the Baltic Proper and related Kattegat and Skagerrak basins. The results reveal considerable differences of (129)I concentration in terms of spatial and temporal variability and expose relatively high concentrations in the deep waters. Variability in the concentration of (127)I, stable natural isotope of iodine, seems to follow changes in the seawater salinity, but in oxygen-poor bottom waters sediment diagenetic release may contribute to the concentration of both isotopes in the water body. Inventory estimates show that (129)I in August 2006 (24.2 ± 15.4 kg) is higher than that in April 2007 (14.4 ± 8.3 kg) within the southern and central Baltic Proper whereas almost a constant load occurs in the Kattegat Basin. Calculated model inventory shows correspondence to empirical data and provides a guideline for future environmental assessment on the impact of (129)I load in the studied region.

Abstract. Air sampling for analysis of CO and its isotopic composition (•3C,

Electronic stopping cross sections in silicon carbide for low-velocity ions with 1Z 1 15