Deuterium–hydrogen ratios, electrical conductivity and nitrate for high-resolution dating of polar ice cores

In order to support the very high time resolution required to observe short-term variations in nitrates and all other ions represented by electrical conductivity in polar ice, a Fourier transform infrared spectrometer was developed for measurement of deuterium concentration in ice samples, as an additional support for the timescale of ultra-high resolution. The portable instrument provided the possibility to measure deuterium concentration on exactly the same samples as used for measuring nitrate concentrations and liquid electrical conductivity, thus verifying that the original dating of the annual variations in nitrate was correct. We present basic information about how the high-resolution data were obtained and discuss their reliability and significance.