1. National Institute of Geological Sciences, College of Science, University of the Philippines; Diliman Quezon City 1101 Philippines
2. Department of Environmental Systems Science, Faculty of Science and Engineering; Doshisha University; Kyoto 610-0394 Japan
3. High-Precision Mass Spectrometry and Environment Change Laboratory (HISPEC), Department of Geosciences; National Taiwan University; Taipei 10617 Taiwan, ROC
4. Research Center for Future Earth; National Taiwan University; Taipei 10617 Taiwan, ROC