1. Environmental NMR Centre and Department of Chemistry, University of Toronto, Toronto, Ontario, M1C 1A4 Canada
2. Bruker BioSpin, GmbH, Silberstreifen, D-76287, Rheinstetten, Germany,
3. Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, T6G 2E3, Canada,
4. Department of Geography, University of Otago, P.O. Box 56, Dunedin, New Zealand