Distribution of suspended particulate matter at the equatorial transect in the Atlantic Ocean
<p>A suspended particulate matter distribution against a hydrographical background was studied at the oceanographic transect across the equatorial Atlantic in the year 2000. An area of abnormally high suspended matter volume concentrations was found above the Sierra Leone Rise in the entire wa...
| Main Authors: | , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2021-10-01
|
| Series: | Ocean Science |
| Online Access: | https://os.copernicus.org/articles/17/1421/2021/os-17-1421-2021.pdf |
| Summary: | <p>A suspended particulate matter distribution against a hydrographical
background was studied at the oceanographic transect across the equatorial
Atlantic in the year 2000. An area of abnormally high suspended matter volume
concentrations was found above the Sierra Leone Rise in the entire water
column (eastern part of the transect). The suggested explanation for the
anomaly is based on the ballast hypothesis whereby solid particles are
incorporated as ballast into suspended biogenic aggregates, leading to
increased velocities of sinking. This occurs within the Northwest African
upwelling area, where the plankton exposed to the Saharan dust abundance form
a significant number of aggregates, which are later transported equatorward
via the Canary Current. An intermediate nepheloid layer associated with the Deep
Western Boundary Current was recorded from the South American Slope at depths
of 3200–3700 to 4300 <span class="inline-formula">m</span> above the Para Abyssal Plain. Antarctic Bottom
Water enriched in suspended matter was found mostly in the troughs at
40–41<span class="inline-formula"><sup>∘</sup></span> W. It was detached from the bottom, coinciding with the core
of the flow due to the bottom rise “dam” located up-stream. The grain size
of particles along the entire transect has a polymodal distribution with 2–4
and 8–13 <span class="inline-formula">µm</span> modes. The registered rise in percentage in some parts of the transect of the 7–21 <span class="inline-formula">µm</span> sized particles suggests the
presence of the well-known coarse mode (20–60 <span class="inline-formula">µm</span>) formed by
aggregation of transparent exopolymer particles (mucus).</p> |
|---|---|
| ISSN: | 1812-0784 1812-0792 |