Cosmogenic 32P and 33P used as tracers to study phosphorus recycling in the upper ocean

Lal, D.; Lee, T.

doi:10.1038/333752a0

Cited by 44 publications

(34 citation statements)

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“…The major conclusions from this long-term effort are that the marine P cycle is unexpectedly complex and that the dynamics of the different P pools is likely to have an important influence on rates of total and export production and on the potential sequestration of atmospheric CO 2 . Lal and Lee [1988], Lee et al [1991], and Benitez-Nelson and Buesseler [1999] have measured the activities of cosmogenically produced 32 P and 33 P in TDP, SRP, and particulate P. They concluded that P turnover rates within the dissolved and particulate pools are rapid (<1 day to $2 weeks) and vary over seasonal timescales, that certain dissolved organic P (DOP) compounds are preferentially utilized, and that P plays a significant role in supporting gross and export productivity. These studies, however, are very elaborate, require sampling of large quantities of seawater (>1000 L) and cannot be applied to all water masses because of the relatively short half-lives of the P radionuclides.…”

Section: Marine Phosphorus Cyclementioning

confidence: 99%

Rapid biologically mediated oxygen isotope exchange between water and phosphate

Paytan

Kolodny

Neori

et al. 2002

Global Biogeochemical Cycles

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Section: Marine Phosphorus Cyclementioning

confidence: 99%

Rapid biologically mediated oxygen isotope exchange between water and phosphate

Paytan

Kolodny

Neori

et al. 2002

Global Biogeochemical Cycles

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“…32 P and 33 P are produced in the atmosphere via cosmogenic interactions with argon and enter the oceans via wet and dry deposition, presumably as phosphate (Lal et al 1960;Lal and Peters 1967;Waser and Bacon 1995;Benitez-Nelson and Buesseler 1999a). If the input ratio is either known or assumed to be constant, then the 33 P/ 32 P activity ratio in any selected P reservoir will increase with increasing age because of the differential decay rates.…”

Section: P/mentioning

confidence: 99%

“…For example, if the 33 P/ 32 P input activity ratio was 1.0 at time zero, it would be 1.16 after 1 week and 1.35 after 1 month using a simple steadystate model. Thus, it is possible to estimate the residence times of radioactive P within various size classes integrated over the mean lives of the radionuclides ( 32 ϭ 20.6 d, 33 ϭ 36.5 d) (Lal and Lee 1988;Waser et al 1996;BenitezNelson and Buesseler 1999b).…”

Section: P/mentioning

confidence: 99%

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Phosphorus cycling in the North Pacific Subtropical Gyre using cosmogenic ³²P and ³³P

Benítez-Nelson

Karl

2002

Limnology & Oceanography

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The North Pacific Subtropical Gyre (NPSG) has been hypothesized to be in transition from a nitrogen (N)-limited system to one predominantly limited by phosphorus (P) as a result of a two-decade-long selection for N 2 -fixing organisms. In this study, the naturally occurring cosmogenic radioisotopes, 32 P (half-life ϭ 14.3 d) and 33 P (halflife ϭ 25.3 d), were measured and 33 P/ 32 P activity ratios were used to estimate radioactive P residence times at Sta. ALOHA (22Њ45ЈN, 158Њ00ЈW) in the NPSG from February 1999 to July 2000. The 33 P/ 32 P activity ratio in the total dissolved P pool varied considerably but systematically; high ratios correlated with periods of enhanced primary production ( 14 C incorporation). Marine particulate 33 P/ 32 P activity ratios were similar to those found in the source (i.e., rain). Smaller size classes had longer apparent residence times. The observation that the activity ratio of 33 P/ 32 P closely follows primary production suggests that atmospherically derived 32 P and 33 P atoms track the most ''bioavailable'' pool of P within the NPSG ecosystem. These preferred substrates were removed from the dissolved phase via plankton uptake during periods of high productivity. Our results suggest that the soluble nonreactive P pool, which is substantially larger than the soluble reactive P pool, is a potentially important source of P to organisms and that its utilization can vary significantly on scales of weeks to months.Phosphorus (P) is an essential nutrient for all living organisms. Compared to studies of carbon (C) or nitrogen (N), two additional bioelements, the distributions and dynamics of inorganic and organic P pools in seawater are less well characterized. Recent evidence suggests that P and trace elements (especially iron) may play a significant role in limiting primary production and nitrogen fixation in selected marine habitats (Martin et al. 1990;Krom et al. 1991;Karl et al. 1997;Behrenfeld and Kolber 1999;Wu et al. 2000;Karl et al. 2001; Sañudo-Wilhelmy et al. 2001). This is particularly true in the western North Atlantic, where enhanced dust deposition has resulted in severe P limitation (Wu et al. 2000). In the North Pacific Subtropical Gyre (NPSG), there is also a hypothesized climate-induced transition from N to P limitation, potentially due to increasing blooms of N 2 -fixing organisms . As a result, it is essential that we understand the composition and the residence times of the various P pools within oligotrophic regimes because they may directly affect the magnitude of global primary production and, hence, nutrient cycling and export in the world's oceans. 1 To whom correspondence should be addressed. Present address: University of South Carolina, Department of Geological Sciences, 700 Sumter Street, Columbia, South Carolina 29208 (cbnelson@ geol.sc.edu). AcknowledgmentsWe thank the HOT program personnel and the crews of the R/V Moana Wave and R/V Ka'imikai-O-Kanaloa for assistance in sample collection. C.B.-N. also thanks B. Popp for allowing her to joi...

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“…Previous workers have used cosmogenic isotopes ( 33 P and 32 P) to study P turnover in the coastal ocean (Lal and Lee 1988;Benitez-Nelson and Buesseler 1999). Their results indicate that P recycling rates are rapid (less than a day to two weeks) and seasonally variable, which suggests that low P concentrations can support relatively high primary production.…”

mentioning

confidence: 99%

A time series investigation of the oxygen isotopic composition of dissolved inorganic phosphate in Monterey Bay, California

et al. 2006

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We present a 2-yr time series of the oxygen isotopic composition of dissolved inorganic phosphate (d 18 O p ) in Monterey Bay, California. d 18 O p can serve as a proxy for phosphate utilization because its approach toward isotopic equilibrium is a function of the degree of biological phosphate cycling. When phosphate is extensively cycled by the biological community in the euphotic zone, the d 18 O p approaches isotopic equilibrium with surrounding water. Our results indicate that d 18 O p in the upper water column is consistently out of isotopic equilibrium with respect to seawater and fluctuates between the equilibrium value and the isotopic signatures of phosphate sources. This suggests that either phosphate is not extensively utilized or that the input of new phosphate to the bay exceeds the requirements of the biological community. d 18 O p is variable and linked to episodic upwelling events and the biotic response to these events. The greatest percent of phosphate oxygen exchange, and thus the greatest phosphate utilization relative to input, occurs at the locus of upwelling (Sta. M1), followed by the offshore (M2) and nearshore (C1) stations, respectively. During the highly productive upwelling season, phosphate turnover is greater than in the winter. Episodes of higher phosphate turnover, as indicated by peaks in d 18 O p , occur simultaneously throughout the upper 200 m of the water column and at all three stations, indicating that these events affect the bay on a large scale. d 18 O p data also suggest that deep water (.500 m) may be a source of phosphate to the euphotic zone in Monterey Bay.

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Cosmogenic 32P and 33P used as tracers to study phosphorus recycling in the upper ocean

Cited by 44 publications

References 14 publications

Rapid biologically mediated oxygen isotope exchange between water and phosphate

Rapid biologically mediated oxygen isotope exchange between water and phosphate

Phosphorus cycling in the North Pacific Subtropical Gyre using cosmogenic ³²P and ³³P

A time series investigation of the oxygen isotopic composition of dissolved inorganic phosphate in Monterey Bay, California

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Cosmogenic 32P and 33P used as tracers to study phosphorus recycling in the upper ocean

Cited by 44 publications

References 14 publications

Rapid biologically mediated oxygen isotope exchange between water and phosphate

Rapid biologically mediated oxygen isotope exchange between water and phosphate

Phosphorus cycling in the North Pacific Subtropical Gyre using cosmogenic 32P and 33P

A time series investigation of the oxygen isotopic composition of dissolved inorganic phosphate in Monterey Bay, California

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Product

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Phosphorus cycling in the North Pacific Subtropical Gyre using cosmogenic ³²P and ³³P