Redfield ratio

The Redfield Ratio describes the proportions of the atomic composition of marine phytoplankton .

Redfield discovered the linear material relationship named after him in 1934 in empirical studies. In 1963 he and two co-authors published the values that are still widely used today:

1 mole P: 16 moles N: 106 moles C

This means that with unlimited nutrients, the plankton contains 16 moles of nitrogen and 106 moles of carbon per mole of phosphorus .

The importance of the Redfield ratio for oceanography and marine biology results from the fact that plankton is the basis of the (autochthonous) food pyramid .

Calculate with the Redfield ratio

${\ displaystyle C_ {106} H_ {263} O_ {110} N_ {16} P_ {1}}$ = 3550 g mol ⁻¹

With a phosphorus content ( atomic mass = 31 g · mol ⁻¹ ) of 1 kg, the Redfield ratio results in a biomass of 114.5 kg.

${\ displaystyle {\ frac {1000g} {31g / Mol}} = 32.26mol}$

32.26 mol 3550 g mol ⁻¹ = 114.516 g = 114.5 kg

Application in the aquarium hobby

The Redfield ratio is sometimes used in aquaristics to overcome green or blue algae infestation . For this purpose, after measuring nitrate and phosphate in the water, the ratio of which - according to Andreas Groß - should be in a certain “green” range, the minimum factor as potassium nitrate or potassium phosphate is added. However, since the Redfield ratio relates to the ratio of phosphorus and nitrogen (as well as carbon) in marine plankton, the transfer to the required amounts of fertilizers for aquarium plants lacks a scientific basis, especially since Redfield does not have the ratios in the water, but the in the biomass of green and blue algae.

literature

W. Fennel, T. Neumann: Introduction to the Modeling of Marine Ecosystems: With MATLAB Programs on Accompanying CD-ROM. Elsevier Oceanography (Paperback) 2004
Roger B. Hanson (Ed.): The Changing Ocean Carbon Cycle: A Midterm Synthesis of the Joint Global Ocean Flux Study. International Geosphere-Biosphere Program Book Series 2000

Individual evidence

↑ Alfred C. Redfield: On the proportions of organic derivatives in sea water and their relation to the composition of plankton. In: James Johnstone Memorial Volume. Edited by RJ Daniel. University Press of Liverpool, 1934, pp. 176-192 ( PDF ). (In this publication Redfield gave the ratio as 1:20: 140.)
↑ Jack J. Middelburg: Marine Carbon Biogeochemistry - A Primer for Earth System Scientists (= SpringerBriefs in Earth System Sciences ). 2019, ISBN 978-3-03010821-2 , 6.1 Redfield Organic Matter, doi : 10.1007 / 978-3-030-10822-9 .
^ ^A ^b Alfred C. Redfield, BH Ketchum and FA Richards: The influence of organisms on the composition of sea-water. In: In The Sea. Ideas and observations on progress in the study of the sea. Volume 2, ed. by MN Hill, Wiley Interscience, New York, 1963, pp. 26-77 ( online )
↑ Andreas Groß: Use of the Redfield ratio for the removal of green and blue algae , 2008/2009
↑ Bernd [Kaufmann]: The Redfield ratio, the fight against algae and the theft of images (Online: Aquamax-Weblog , 2009)

[1] Alfred C. Redfield: On the proportions of organic derivatives in sea water and their relation to the composition of plankton. In: James Johnstone Memorial Volume. Edited by RJ Daniel. University Press of Liverpool, 1934, pp. 176-192 ( PDF ). (In this publication Redfield gave the ratio as 1:20: 140.)

[2] Jack J. Middelburg: Marine Carbon Biogeochemistry - A Primer for Earth System Scientists (= SpringerBriefs in Earth System Sciences ). 2019, ISBN 978-3-03010821-2 , 6.1 Redfield Organic Matter, doi : 10.1007 / 978-3-030-10822-9 .

[redfield1963-3] A ^b Alfred C. Redfield, BH Ketchum and FA Richards: The influence of organisms on the composition of sea-water. In: In The Sea. Ideas and observations on progress in the study of the sea. Volume 2, ed. by MN Hill, Wiley Interscience, New York, 1963, pp. 26-77 ( online )

[4] Andreas Groß: Use of the Redfield ratio for the removal of green and blue algae , 2008/2009

[5] Bernd [Kaufmann]: The Redfield ratio, the fight against algae and the theft of images (Online: Aquamax-Weblog , 2009)