Effects of dust deposition on iron cycle in the surface Mediterranean Sea: results from a mesocosm seeding experiment

Wagener, Thibaut; Guieu, Cécile; Leblond, Nathalie

doi:10.5194/bg-7-3769-2010

Cited by 77 publications

(110 citation statements)

References 48 publications

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“…How is it possible to interpret these in an integrative way? Wagener et al (2010) pointed out that the initial iron concentration before the dust addition was at the higher end of former measurements in that region. A Saharan dust deposition two weeks before the DUNE experiment and the rain events days before are supposed to be responsible for the high DFe initial concentration.…”

Section: Role Of Dust Deposition In Iron Replete Watersmentioning

confidence: 98%

“…The high export within the first 24 h in the model is caused by the aggregation of P s which initially after the dust addition has a very high concentration close to the surface. This must have happened, since otherwise, particles could not be exported out of the upper 10 m within the first 48 h as observed by Wagener et al (2010).…”

Section: Particle Dynamicsmentioning

confidence: 99%

“…Iron budget estimated from measured data and model (mg) under dust addition. D1-D2 stand for the two mesocosms with dust addition shown in Wagener et al (2010) and M for model results. Time (0-168) is in hours after dust addition.…”

Section: Iron Budgetmentioning

confidence: 99%

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Dust deposition: iron source or sink? A case study

Wagener

Völker

et al. 2011

Biogeosciences

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Abstract. A significant decrease of dissolved iron (DFe) concentration has been observed after dust addition into mesocosms during the DUst experiment in a low Nutrient low chlorophyll Ecosystem (DUNE), carried out in the summer of 2008. Due to low biological productivity at the experiment site, biological consumption of iron can not explain the magnitude of DFe decrease. To understand processes regulating the observed DFe variation, we simulated the experiment using a one-dimensional model of the Fe biogeochemical cycle, coupled with a simple ecosystem model. Different size classes of particles and particle aggregation are taken into account to describe the particle dynamics. DFe concentration is regulated in the model by dissolution from dust particles and adsorption onto particle surfaces, biological uptake, and photochemical mobilisation of particulate iron.The model reproduces the observed DFe decrease after dust addition well. This is essentially explained by particle adsorption and particle aggregation that produces a high export within the first 24 h. The estimated particle adsorption rates range between the measured adsorption rates of soluble iron and those of colloidal iron, indicating both processes controlling the DFe removal during the experiment. A dissolution timescale of 3 days is used in the model, instead of an instantaneous dissolution, underlining the importance of dissolution kinetics on the short-term impact of dust deposition on seawater DFe.Sensitivity studies reveal that initial DFe concentration before dust addition was crucial for the net impact of dust addition on DFe during the DUNE experiment. Based on the balance between abiotic sinks and sources of DFe, a critical DFe concentration has been defined, above which dust depoCorrespondence to: Y. Ye (ying.ye@awi.de) sition acts as a net sink of DFe, rather than a source. Taking into account the role of excess iron binding ligands and biotic processes, the critical DFe concentration might be applied to explain the short-term variability of DFe after natural dust deposition in various different ocean regions.

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Section: Role Of Dust Deposition In Iron Replete Watersmentioning

confidence: 98%

Section: Particle Dynamicsmentioning

confidence: 99%

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Dust deposition: iron source or sink? A case study

Wagener

Völker

et al. 2011

Biogeosciences

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“…Iron is also scavenged by lithogenic particles originating from dust deposition as evidenced by mesocosm experiments (Wagener et al, 2010). The concentration of lithogenic particles is estimated as described in Eq.…”

Section: Iron In Particlesmentioning

confidence: 99%

PISCES-v2: an ocean biogeochemical model for carbon and ecosystem studies

Aumont¹,

et al. 2015

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Abstract. PISCES-v2 (Pelagic Interactions Scheme for Carbon and Ecosystem Studies volume 2) is a biogeochemical model which simulates the lower trophic levels of marine ecosystems (phytoplankton, microzooplankton and mesozooplankton) and the biogeochemical cycles of carbon and of the main nutrients (P, N, Fe, and Si). The model is intended to be used for both regional and global configurations at high or low spatial resolutions as well as for short-term (seasonal, interannual) and long-term (climate change, paleoceanography) analyses. There are 24 prognostic variables (tracers) including two phytoplankton compartments (diatoms and nanophytoplankton), two zooplankton size classes (microzooplankton and mesozooplankton) and a description of the carbonate chemistry. Formulations in PISCES-v2 are based on a mixed Monod-quota formalism. On the one hand, stoichiometry of C / N / P is fixed and growth rate of phytoplankton is limited by the external availability in N, P and Si. On the other hand, the iron and silicon quotas are variable and the growth rate of phytoplankton is limited by the internal availability in Fe. Various parameterizations can be activated in PISCES-v2, setting, for instance, the complexity of iron chemistry or the description of particulate organic materials. So far, PISCES-v2 has been coupled to the Nucleus for European Modelling of the Ocean (NEMO) and Regional Ocean Modeling System (ROMS) systems. A full description of PISCES-v2 and of its optional functionalities is provided here. The results of a quasi-steady-state simulation are presented and evaluated against diverse observational and satellite-derived data. Finally, some of the new functionalities of PISCES-v2 are tested in a series of sensitivity experiments.

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“…However, several studies, based on microcosm experiments, have been performed to better understand the influence of atmospheric dust deposition on the functioning and productivity in low-nutrient low-chlorophyll (LNLC) environments, either in the Atlantic Ocean (Blain et al, 2004;Mills et al, 2004;Moore et al, 2008;Marañón et al, 2010), Pacific Ocean (Law et al, 2011), or Mediterranean Sea (e.g., Pulido-Villena et al, 2008;Wagener et al, 2010).…”

Section: Giovagnetti Et Al: Assessing the Role Of Dust Depositionmentioning

confidence: 99%

Assessing the role of dust deposition on phytoplankton ecophysiology and succession in a low-nutrient low-chlorophyll ecosystem: a mesocosm experiment in the Mediterranean Sea

Giovagnetti

Brunet²,

Conversano³

et al. 2013

Biogeosciences

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In this study, we investigate the response of the phytoplankton community, with emphasis on ecophysiology and succession, after two experimental additions of Saharan dust in the surface water layer of a low-nutrient low-chlorophyll ecosystem in the Mediterranean Sea. Three mesocosms were amended with evapocondensed dust to simulate realistic Saharan dust events, while three additional mesocosms were kept unamended and served as controls. The experiment consisted in two consecutive dust additions and samples were daily collected at different depths (−0.1, −5 and −10 m) during one week, starting before each addition occurred. Data concerning HPLC pigment analysis on two size classes (< 3 and > 3 μm), electron transport rate (ETR) vs. irradiance curves, non-photochemical fluorescence quenching (NPQ) and phytoplankton cell abundance (measured by flow cytometry), are presented and discussed in this paper. Results show that picophytoplankton mainly respond to the first dust addition, while the second addition leads to an increase of both pico- and nano-/microphytoplankton. Ecophysiological changes in the phytoplankton community occur, with NPQ and pigment concentration per cell increasing after dust additions. While biomass increases after pulses of new nutrients, ETR does not greatly vary between dust-amended and control conditions, in relation with ecophysiological changes within the phytoplankton community, such as the increase in NPQ and pigment cellular concentration. A quantitative assessment and parameterisation of the onset of a phytoplankton bloom in a nutrient-limited ecosystem is attempted on the basis of the increase in phytoplankton biomass observed during the experiment. The results of this study are discussed focusing on the adaptation of picophytoplankton to nutrient limitation in the surface water layer, as well as on size-dependent competition ability in phytoplankton

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Effects of dust deposition on iron cycle in the surface Mediterranean Sea: results from a mesocosm seeding experiment

Cited by 77 publications

References 48 publications

Dust deposition: iron source or sink? A case study

Dust deposition: iron source or sink? A case study

PISCES-v2: an ocean biogeochemical model for carbon and ecosystem studies

Assessing the role of dust deposition on phytoplankton ecophysiology and succession in a low-nutrient low-chlorophyll ecosystem: a mesocosm experiment in the Mediterranean Sea

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