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Twin cosmogenic radiotracer studies of phosphorus recycling and chemical fluxes in the upper ocean
Author(s) -
Lai D.,
Chung Y.,
Platt T.,
Lee T.
Publication year - 1988
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1988.33.6part2.1559
Subject(s) - seawater , phytoplankton , environmental chemistry , pelagic zone , phosphorus , thermocline , zooplankton , radionuclide , oceanography , environmental science , plankton , chemistry , nutrient , geology , physics , organic chemistry , quantum mechanics
We determined the feasibility of using two cosmogenic radionuclides, 32 P (half life, 14.3 d) and 33 P (half‐life, 25.3 d) as tracers for studying nutrient cycling and chemical fluxes in the upper layers of the ocean. Various chemical procedures were tried to extract dissolved inorganic phosphorus (DIP) from several thousand liters of seawater as required to measure the natural activities of 32 P and 33 P. We developed a simple and convenient procedure for extraction of DIP from about 10 3 liters of seawater h 1 , simultaneously from several depths. The activities of 32 P and 33 P were measured with a low‐level Q‐gas flow counter. The 32 P activities in coastal waters off La Jolla and San Diego range between 0.5 and 0.9 dpm m ‒3 of seawater. The 32 P‐specific activities in coastal plankton samples range between 20 and 100 [dpm (g P) ‒1 ], zooplankton samples being consistently lower than phytoplankton samples. The phytoplankton samples have 32 P activities (dpm m ‒3 of seawater) close to those in surface waters. The observed concentrations and specific activities of these tracers in dissolved and particulate phosphorus pools are in excellent agreement with expectations. Our studies demonstrate their usefulness as suitable tracers for studies of P pathways through the pelagic food chain and P flux through the thermocline, averaged over a time scale of 1–2 months.