Particulate trace element fluxes in the deep northeast Atlantic Ocean

Particulate fluxes of trace elements (Al, Cd, Co, Cu, Fe, Mn, Ni, P, Ti, V and Zn) in the northeast Atlantic Ocean (three positions at latitudes from 33 degrees N to 54 degrees N along similar to 20 degrees W) were measured u sing time-series sediment traps between March 1992 and September 1994. Sign ificant variabilities of fluxes with season and depth (1000 m to maximum of 4000 m) were observed only for 'biogenic elements', such as Cd, Ni, Zn or P. On the other hand, we found a distinct large-scale increase of fluxes in to the deep-sea traps to the south for Al, Co, Fe, Mn and V. We attribute t his latitudinal gradient to the increasing influence of the Saharan dust pl ume. The biogenic Aux decreased towards the south. This trend was clearly v isible for Cd and P only. The fluxes of other 'nutrient-like' elements, suc h as Ni or Zn, exhibited a general decrease between 53 degrees N and 33 deg rees N. We compared our sedimentation flux data with published data from th e western North Atlantic basins. For this purpose we corrected the deep-sea fluxes of Cu, Mn, Ni and Zn for their lithogenic fractions on the basis of Al, with average crustal material and granitic rocks as references. The co mparison indicates that these 'excess' fluxes are a factor of at least 2 hi gher in the western basins for the selected elements. Estimated fluxes are in good agreement with reported atmospheric deposition in the two areas. Th e noted imbalance between the non-lithogenic atmospheric input of Mn and th e determined 'excess flux' in the deep northeast Atlantic indicates an addi tional input in the form of a lateral flux of dissolved Mn(II) species and scavenging onto sinking particles. With respect to the mechanism of sedimen tation, a unique behaviour is noticed for the refractory elements Co, Fe, M n, Ti and V, which were found to correlate with the vertical transport of A l (clay). The 'excess' fluxes of Cu, Ni and Zn are linearly related to C-or g, whereas the overall relation of Cd to P fluxes exhibits a molar Cd/P rat io of 2.0 x 10(-4), which is close to the ratio in the dissolved fractions in the northeast Atlantic. (C) 1999 Elsevier Science Ltd. All rights reserv ed.