Pumping iron makes thinner diatoms

Article Abstract:

It has been possible to demonstrate that iron affects diatom uptake of silica relative to nitrate. This indicates that iron has a much more extensive role in regulating oceanic biogeochemical cycles than had previously been realized. It was shown that adding iron boosts the reproduction rates and nitrate uptake of natural phytoplankton communities incubated in the laboratory. Increased productivity is almost entirely due to the response of large diatoms, which have characteristics including a siliceous skeleton.

Soils, Iron (Metal), Soil chemistry, Diatoms

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Deep water distillation

Article Abstract:

The North Atlantic Deep Water current transports Atlantic waters into the southern and global oceans at the same rate as during the Last Glacial Maximum. Sedimentary 231Pa/230Th data reveal a deficiency of 231Pa and an increase in radioisotope ratio in the surface sediments of the Southern Ocean. Sedimentary 231Pa/230Th is an efficient indicator of past biological productivity as it bears strong correlation to the total particle flux. Chronological validity of the NADW conveyor operation is discussed.

Abyssal zone, Radioactivity, Atlantic Ocean, North Atlantic Ocean, Radioisotopes, Ocean currents

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Measures of productivity

Article Abstract:

Two new techniques for measuring the productivity of marine plankton have been developed. This is important because plankton productivity may indicate levels of atmospheric carbon dioxide (CO2) during ancient glacial periods. R. Francois and colleagues used nitrogen isotope levels to deduce productivity while N. Kumar and colleagues used protactinium-thorium isotope levels. Both techniques show that plankton productivity and CO2 levels fluctuated during glacial epochs.

Isotopes, Thorium, Nitrogen, Marine plankton, Atmospheric carbon dioxide, Nitrogen isotopes, Paleoceanography

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