Han Chen, The Chinese University of Hong Kong, Earth System Science Programme, Faculty of Science, Hong Kong, China, Hongfeng Yang, Earth System Science Programme, Faculty of Science, Chinese University of Hong Kong, Hong Kong, Hong Kong, Jian Lin, Woods Hole Oceanographic Inst, G & G, Woods Hole, MA, United States; Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China, Gaohua Zhu, Chinese University of Hong Kong, Earth System Science Programme, Hong Kong 999077, China and Jiangyang Zhang, Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China