Estimating the compensation irradiance in the ocean: The importance of accounting for non-photosynthetic uptake of inorganic carbon

Document Type

Article

Publication Date

1-1-2014

Abstract

The compensation irradiance, the irradiance at which net photosynthesis is zero over a 24-h period, was estimated at station ALOHA (22°45'N, 158°W) from analysis of 14C uptake rates measured from 8 January 1989 to 13 June 1990 at depths ranging from 5 to 175m. The estimates were made on the basis of linear regressions of the difference between light bottle and dark bottle 14C uptake in the light-limited region of the euphotic zone and determination of the depth at which the difference between the uptake rates was zero. About half of the non-photosynthetic 14C uptake at the compensation irradiance could be attributed to chemolithoautotrophy; the remainder was presumably due to anaplerotic processes. Deriving the compensation irradiance by extrapolating dawn-to-dawn light-bottle uptake above the compensation irradiance to zero resulted in underestimation of the compensation irradiance by a factor of 2. We estimated the compensation irradiance at station ALOHA to be 0.054mol-photons m-2d-1, about 0.11% of surface 400-700nm radiation and 1% of surface 475-nm (blue) light. © 2014.

Publication Source (Journal or Book title)

Deep Sea Research Part I Oceanographic Research Papers

First Page

35

Last Page

40

This document is currently not available here.

Share

COinS