Nitrogen fixation by Trichodesmium spp.:: An important source of new nitrogen to the tropical and subtropical North Atlantic Ocean -: art. no. GB2024

被引:460
作者
Capone, DG [1 ]
Burns, JA
Montoya, JP
Subramaniam, A
Mahaffey, C
Gunderson, T
Michaels, AF
Carpenter, EJ
机构
[1] Univ So Calif, Wrigley Inst Environm Studies, Los Angeles, CA 90275 USA
[2] Univ So Calif, Dept Biol Sci, Los Angeles, CA 90275 USA
[3] Georgia Inst Technol, Sch Biol, Atlanta, GA 30332 USA
[4] Columbia Univ, Lamont Doherty Earth Observ, Palisades, NY 10964 USA
[5] San Francisco State Univ, Romberg Tiburon Ctr, Tiburon, CA 94920 USA
关键词
D O I
10.1029/2004GB002331
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
[1] The broad distribution and often high densities of the cyanobacterium Trichodesmium spp. in oligotrophic waters imply a substantial role for this one taxon in the oceanic N cycle of the marine tropics and subtropics. New results from 154 stations on six research cruises in the North Atlantic Ocean show depth-integrated N-2 fixation by Trichodesmium spp. at many stations that equalled or exceeded the estimated vertical flux of NO3- into the euphotic zone by diapycnal mixing. Areal rates are consistent with those derived from several indirect geochemical analyses. Direct measurements of N-2 fixation rates by Trichodesmium are also congruent with upper water column N budgets derived from parallel determinations of stable isotope distributions, clearly showing that N2 fixation by Trichodesmium is a major source of new nitrogen in the tropical North Atlantic. We project a conservative estimate of the annual input of new N into the tropical North Atlantic of at least 1.6 x 10(12) mol N by Trichodesmium N-2 fixation alone. This input can account for a substantial fraction of the N-2 fixation in the North Atlantic inferred by several of the geochemical approaches.
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页码:1 / 17
页数:17
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