In:
Biogeosciences, Copernicus GmbH, Vol. 16, No. 7 ( 2019-04-12), p. 1563-1582
Abstract:
Abstract. The aim of the GEOVIDE cruise (May–June 2014, R/V Pourquoi Pas?)
was to provide a better understanding of trace metal biogeochemical cycles in
the North Atlantic Ocean. As marine particles play a key role in the global
biogeochemical cycle of trace elements in the ocean, we discuss the
distribution of particulate iron (PFe), in relation to the distribution of
particulate aluminium (PAl), manganese (PMn), and phosphorus (PP). Overall,
32 full vertical profiles were collected for trace metal analyses,
representing more than 500 samples. This resolution provides a solid basis
for assessing concentration distributions, elemental ratios, size
fractionation, and adsorptive scavenging processes in key areas of the
thermohaline overturning circulation. Total particulate iron concentrations
ranged from as low as 9 pmol L−1 in surface waters of the Labrador Sea
to 304 nmol L−1 near the Iberian margin, while median PFe
concentrations of 1.15 nmol L−1 were measured over the sub-euphotic
ocean interior. Within the Iberian Abyssal Plain, the ratio of PFe to PAl was identical to
the continental crust molar ratio (0.21 mol mol−1), indicating the
important influence of crustal particles in the water column. Overall, the
lithogenic component explained more than 87% of PFe variance along the
section. Within the Irminger and Labrador basins, the formation of biogenic
particles led to an increase in the PFe∕PAl ratio (up to
0.64 mol mol−1) compared to the continental crust ratio. Continental
margins induce high concentrations of particulate trace elements within the
surrounding water masses (up to 10 nmol L−1 of PFe). For example,
horizontal advection of PFe was visible more than 250 km away from the
Iberian margin. Additionally, several benthic nepheloid layers were observed
more than 200 m above the seafloor along the transect, especially in the
Icelandic, Irminger, and Labrador basins, suspending particles with high PFe
content of up to 89 nmol L−1.
Type of Medium:
Online Resource
ISSN:
1726-4189
DOI:
10.5194/bg-16-1563-2019
DOI:
10.5194/bg-16-1563-2019-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2019
detail.hit.zdb_id:
2158181-2
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