Zhouling Zhang^1,2, Stefan Sommer³, Xiaole Sun⁴, Andrew Dale³, Martin Frank³, Minhan Dai¹ and Daniel J Conley², (1)State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China, (2)Department of Geology, Lund University, Lund, Sweden, (3)GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany, (4)Baltic Sea Center, Stockholm University, Stockholm, Sweden