Photometer for the continuous measurement of calcite-dependent light scatter in seawater

Katherine A. Kilpatrick; William M. Balch; Yuntao Ge; Kenneth John Voss

doi:10.1117/12.190093

26 October 1994 Photometer for the continuous measurement of calcite-dependent light scatter in seawater

Katherine A. Kilpatrick, William M. Balch, Yuntao Ge, Kenneth John Voss

Proceedings Volume 2258, Ocean Optics XII; (1994) https://doi.org/10.1117/12.190093
Event: Ocean Optics XII, 1994, Bergen, Norway

Abstract

Biogenically produced calcite represents a significant source of light scatter in the ocean, poorly defined in space and time. We describe an automated photometer for measuring 90 degree(s) light scatter due to calcite on time scales as short as a minute. Raw seawater continuously flows through a 1 mL glass cuvette illuminated by a helium-neon laser. A photodiode is used to measure the 90 degree(s) light scatter of particles in the incident beam. During each sampling interval, a calibrated addition of weak acid lowers the seawater pH to dissolve the calcite and another 90 degree(s) light scatter measurement is made. Standard curves are prepared using calcium carbonate coccoliths from the coccolithophore Emiliania huxleyi. The relationships between acid-liable light scatter and coccolith abundance given an r² of 0.96 - 0.99. The light scatter photometer is coupled to a fluorometer, temperature and salinity probe to relate the suspended calcite concentration to algal distributions and hydrography. We show some examples of its performance at sea.

Citation Download Citation

Katherine A. Kilpatrick, William M. Balch, Yuntao Ge, and Kenneth John Voss "Photometer for the continuous measurement of calcite-dependent light scatter in seawater", Proc. SPIE 2258, Ocean Optics XII, (26 October 1994); https://doi.org/10.1117/12.190093

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