Global distribution of 129I in rivers and lakes: implications for iodine cycling in surface reservoirs
Iodine and 129I concentrations as well as 129I/I ratios were measured in 72 samples from lakes and rivers in order to report the global distribution of anthropogenic 129I. The highest values in ratios and 129I concentrations were found in the mid-latitudes of the Northern Hemisphere, but levels above pre-anthropogenic were found in all samples, including those from the high Arctic and from Antarctica. Low values are observed in equatorial regions, but another maximum is present in the mid-latitudes of the Southern Hemisphere, although it is smaller than that in the Northern Hemisphere. The distribution demonstrates on a global scale the rapid atmospheric transport of 129I from its sources, reprocessing plants located in the Northern Hemisphere. The minimum in 129I concentrations observed at low latitudes probably indicates that the overall remobilization of iodine is a function of regional soil ecosystems.