Low 15N/14N ratios for nitrate in snow in the High Arctic (79°N)

We report on the N-15/N-14 and O-18/O-16 ratio analysis of nitrate in accumalated winter snowpack and fresh spring snow collected near Ny Alesund, Svalbard (79degreesN), in the early summers of 2001-2003. The presence of contaminant organic matter in the silver nitrate prepared for analysis must be carefully monitored to assess its effects on delta(15)N, and particularly delta(18)O results. delta(15)N values ranged -18parts per thousand to -7parts per thousand (versus air N-2) and delta(18)O values + 60 to + 85parts per thousand (versus VSMOW). The delta(18)O values are in the reported range for atmospheric nitrate in other parts of the globe, and will tend to reflect the relationship between NOy oxygen and H2O + O-2 in the troposphere immediately prior to nitrate deposition. delta(15)N values, however, are lower than those for atmospheric nitrate over most parts of the globe, but show similarities to N-15/N-14 ratios reported for atmospheric nitrate in the Antarctic. We discuss mechanisms for producing N-15-depleted nitrate in the troposphere, or the possibility that it reflects NOy nitrogen derived from the stratosphere. Crown Copyright (C) 2004 Published by Elsevier Ltd. All rights reserved.