The stable isotopes Hydrogen-2 and Oxygen-18 found in rainwater have been collected and mapped as a ratio across the country, forming a base dataset for potentially establishing the point of origin of biological materials. The maps reveal patterns in space and time and indicate new locations for sampling.
Data and method
As part of the Cross Departmental Research Project (CDRP), analysis of rainwater collected from weather stations across New Zealand has led to identification of the stable isotope composition of precipitation throughout the country. Stable isotope data from January 2007 to February 2008 was available for analysis in a Geographic Information System (GIS), with the aim of producing maps displaying the isotopic variability of rainfall across New Zealand. The data was composed of delta values for the stable isotope ratios of 2H (or deuterium) and 18Oxygen acquired from each station's monthly rainfall.
Results & achievements
The work in the project report aims to contribute to the CDRP's aims of establishing the point of origin of biological materials, with the mapping procedure supplying predictions of isotopic composition in areas where rainfall is not currently sampled or analysed.
Maps on isotopic ratio, deuterium excess, rainfall, temperature, humidity, absolute abundance of Hydrogen-2 and absolute abundance of Oxygen-18 for each month from January 2007 to February 2008 have been produced.
Collaborations
Liz Metsers (now with Department of Conservation, Invercargill)
Russell Frew (Department of Chemistry)
Mike Darling (Oritain Ltd)
Funding from Biosecurity NZ and Department of Chemistry
Selected publications and outcomes
Metsers, L, Moore, A, Frew, R and Darling, M. 2009. "Isotopic Variability of Rainfall across New Zealand, January 2007 - February 2008" Report for Biosecurity NZ, 57pp