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Author(s): de Baar HJW, Gerringa LJA, Laan P, Timmermans KR
Published: July, 2008
Publisher: Marine Ecology Progress Series
DOI: 10.3354/meps07548
Tags: Ocean Fertilization
URL: http://www.int-res.com/abstracts/meps/v364/p269-282/
Abstract: The major response to ocean iron fertilization is by large diatoms, which at Fe-replete ambient seawater show an optimum C:Fe elemental ratio of ~23000 and a higher ratio of ~160000 or more under Fe-limited conditions. The efficiency of CO2 drawdown during the several weeks of artificial fertilization experiments with concomitant observations is in the range of 100 < (CO2:Fe) < 1000 and is unknown in direction (positive or negative) and magnitude in the period after observations. The efficiency of biogenic carbon export into deeper water layers ranges from ~650 < (C:Fe)export < ~25000 for reported export depths in the 100 to 250 m range. Variations in ocean initial conditions and variable weather during an experiment cause this range of ~2 orders of magnitude. Approximately 75% of Fe added in fertilization experiments is lost very rapidly. Hence the above efficiencies can be multiplied 4-fold, to ~2600 < (C:Fe)export < ~100000, for the sake of comparison with natural fertilization with Fe-organic complexes, which stabilize Fe in solution. Quantification of the Fe source of natural fertilization is difficult, leading to an export efficiency in the ~2400 < (C:Fe)export < ~800000 range. Due to severe under-sampling, the existing datasets of artificial experiments and natural fertilizations may allow a wider range of alternative assessments than reported here.
Author(s): Buesseler KO, Doney SC, Karl DM, Boyd PW, Caldeira K, Chai F, Coale KH, de Baar HJW, Falkowski PG, Johnson KS, Lampitt RS, Michaels AF, Naqvi SWA, Smetacek V, Takeda S, Watson AJ
Published: January, 2008
Publisher: Science
DOI: 10.1126/science.1154305
Tags: Ocean fertilization, Research
URL: http://www.sciencemag.org/content/319/5860/162.short
Abstract: It is premature to sell carbon offsets from ocean iron fertilization unless research provides the scientific foundation to evaluate risks and benefits.
Author(s): Boyd PW, Jickells TD, Law CS, Blain S, Boyle EA, Buesseler KO, Coale KH, Cullen JJ, de Baar HJW, Follows M, Harvey M, Lancelot C, Levasseur M, Owens NPJ, Pollard RT, Rivkin RB, Sarmiento JL, Schoemann V, Smetacek V, Takeda S, Tsuda A, Turner SM, Watson AJ
Published: February, 2007
Publisher: Science
DOI: 10.1126/science.1131669
Tags: Ocean Fertilization, Research
URL: http://www.sciencemag.org/content/315/5812/612.abstract
Abstract: Since the mid-1980s, our understanding of nutrient limitation of oceanic primary production has radically changed. Mesoscale iron addition experiments (FeAXs) have unequivocally shown that iron supply limits production in one-third of the world ocean, where surface macronutrient concentrations are perennially high. The findings of these 12 FeAXs also reveal that iron supply exerts controls on the dynamics of plankton blooms, which in turn affect the biogeochemical cycles of carbon, nitrogen, silicon, and sulfur and ultimately influence the Earth climate system. However, extrapolation of the key results of FeAXs to regional and seasonal scales in some cases is limited because of differing modes of iron supply in FeAXs and in the modern and paleo-oceans. New research directions include quantification of the coupling of oceanic iron and carbon biogeochemistry.
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