Xianyu Kong¹, Oliver J Lechtenfeld², Jan Kaesler³, Mats A Granskog⁴, Colin A Stedmon⁵, Martin Graeve¹ and Boris P Koch⁶, (1)Alfred Wegener Institute Helmholtz-Center for Polar and Marine Research, Ecological Chemistry, Bremerhaven, Germany, (2)Helmholtz Centre for Environmental Research UFZ, Analytical Chemistry, Leipzig, Germany, (3)Helmholtz Centre for Environmental Research UFZ Leipzig, Analytical Chemistry, Leipzig, Germany, (4)Norwegian Polar Institute, Tromsø, Norway, (5)Technical University of Denmark, National Institute of Aquatic Resources, Kongens Lyngby, Denmark, (6)Alfred Wegener Institute Helmholtz-Center for Polar and Marine Research Bremerhaven, Ecological Chemistry, Bremerhaven, Germany