Particulate trace metal fluxes in the center of an oceanic desert: Northeast Atlantic subtropical gyre

Abstract

For this study particle flux material collected over 13 years period starting in February 2002 until summer 2015 with the long-term mooring Kiel 276 (33°N, 22°W) in the subtropical Northeast Atlantic was analyzed. Our focus was set on the elemental composition and trace element fluxes which we analyzed with the help of ICP-OES and ICP-MS. The particle flux has a mean of 60 mg m −2 d −1 (range: 1–365 mg m −2 d −1 ) with peak fluxes during February and April shortly after the winter bloom. Especially in 2004 high fluxes occurred through the year when the Azores Front was located south of the mooring. In this year enhanced nutrient supply and high dust concentration in the atmosphere were measured. The analyzed trace elements of Cd, Co, Cr, Cu, Ni, V, Zn, Zr, and Mn have mean fluxes of 43.4 μg Cd m −2 d −1 , 205.7 μg Co m −2 d −1 , 1.4 μg Cr m −2 d −1 , 3.2 μg Cu m −2 d −1 , 1.6 μg Ni m −2 d −1 , 1.0 μg V m −2 d −1 , 5.1 μg Zn m −2 d −1 , 1.3 μg Zr m −2 d −1 , and 7.8 μg Mn m −2 d −1 . Biogenic trace elements (Cd, Zn, Ni) show maximum fluxes in winter and spring while no seasonality was present for refractory (Zr) and redox-sensitive elements (V, Mn, Co). Fe, Ti, Co, Mn, V, Mn, and Zr are only little enriched towards the upper continental crust (EF < 2) as these elements originate from a lithogenic source and are little prone to dissolution or scavenging while Cd, Cu, Cr, Ni, and Zn are more enriched with EF of 3.0, 9.6, 2.4, 6.2, and 5.0, respectively. • 13 years long particle flux time series from the subtropical NE Atlantic • Atmospheric pathways and Azores Front modulate particle and trace elemental fluxes. • Deep ocean particulate trace elemental fluxes depend on the biogenic matter cycle.