Trends in the solubility of iron, aluminium, manganese and phosphorus in aerosol collected over the Atlantic Ocean

Baker, Alex R.; Jickells, Timothy D.; Witt, Melanie; Linge, Kathryn L.

doi:10.1016/j.marchem.2005.06.004

Cited by 368 publications

(383 citation statements)

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“…Finally, Miami and Barbados are not strongly affected by biomass burning during the summer when most of the samples were taken. In some other regions, such as sub-Saharan Africa, the relationship between dust and TP may be masked by high levels of biomass burning and lower levels of dust [Baker et al, 2006b;Losno et al, 1992]. The biomass burning samples at our sites provided much less TP (169 AE 142 pmol m À3 ) than the dust days (651 AE 249 pmol m À3 ).…”

Section: Resultsmentioning

confidence: 78%

“…Previous studies in a variety of other locations similarly report higher P solubility in combustion-derived aerosols than in dust (e.g., Bergametti et al [1992], Graham and Duce [1982], Herut et al [1999], Baker et al [2006b]). Although it is possible that marine sea spray particles mixed in with the pollution samples enhanced the apparent solubility, samples where this effect would be greatest were excluded from the analysis (i.e.…”

Section: Srp and Solubilitymentioning

confidence: 73%

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Atmospheric P deposition to the subtropical North Atlantic: sources, properties, and relationship to N deposition

et al. 2013

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[1] Biogeochemical studies show that the surface waters of the subtropical North Atlantic are highly phosphorus (P) stressed. Human activity may exacerbate phosphorus stress by enhancing atmospheric nitrogen (N) deposition and raising N/P ratios in deposition. However, the magnitude of this effect is unclear, in part, because atmospherically deposited phosphorus sources are not well known, particularly the contribution from organic phosphorus. Here we report measurements of phosphorus in aerosols and wet deposition at Miami and Barbados. African dust is the major aerosol P source at both Miami and Barbados, containing~880 ppm total phosphorus and~70 ppm soluble reactive phosphorus (SRP). Organic compounds contribute, on average, 28%-44% of soluble phosphorus in precipitation. Because of dust transport seasonality, phosphorus inputs to the North Atlantic are expected to be highly variable with 2-10 times more P deposition during summer than winter. Pollution is also an important contributor to total and soluble phosphorus in Miami aerosols and deposition. Estimated SRP deposition in Barbados and Miami is 0.21 and 0.13 mmol m À2 d À1 phosphorus, respectively. Inorganic nitrogen in excess of Redfield ratio expectations in deposition was very different between the sites, totaling 21-30 and 127-132 mmol m À2 d À1 nitrogen in Barbados and Miami, respectively; the high deposition rates at Miami are linked to pollutants. Including soluble organic nitrogen and phosphorus halved the estimates of excess nitrogen in Barbados wet deposition. Thus, the organic phosphorus fraction is important in the assessment of the magnitude of biogeochemical change of the North Atlantic caused by atmospheric deposition.Citation: Zamora, L. M., J. M. Prospero, D. A. Hansell, and J. M. Trapp (2013), Atmospheric P deposition to the subtropical North Atlantic: sources, properties, and relationship to N deposition,

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Section: Resultsmentioning

confidence: 78%

Section: Srp and Solubilitymentioning

confidence: 73%

Atmospheric P deposition to the subtropical North Atlantic: sources, properties, and relationship to N deposition

et al. 2013

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“…Just as with riverine iron, however, we know only a little about how much of this iron is biologically utilised. The solubility of iron in dust appears to be low, perhaps less than 1%, but major questions remain concerning the effects of atmospheric cloud recycling on solubility [24][25][26] and the role of photochemistry and organic ligands on iron dissolution and uptake by microbes. [27] Recent work suggests that some upper ocean microbes can assimilate colloidal iron directly.…”

Section: The Global Oceanic Iron Cyclementioning

confidence: 99%

Iron-binding ligands and their role in the ocean biogeochemistry of iron

2007

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Environmental context. It is now well accepted that iron is an essential micronutrient for phytoplankton growth in many areas of the global ocean, even though this element is present in seawater in extremely low abundance. It is also known that most of the iron in seawater is present as complexes formed with ligands of natural organic matter whose nature and origin remain largely unknown. Here we consider how these iron-complexing ligands might have evolved during geological time, what factors may have given rise to their presence and the possible roles that they play in iron biogeochemistry.Abstract. Current knowledge about the role of iron-binding organic ligands in the ocean and their role in determining the biogeochemistry of this biologically active element has been summarised. Some electrochemical measurements suggest the presence of at least two ligand types, a strong binding ligand L 1 found mainly in the mixed layer and a weaker ligand L 2 found mainly in deep water. Speciation of Fe III is dominated by L 1 in the mixed layer and L 2 in the deep ocean. There is some evidence that L 1 is siderophore-like and is specifically generated by marine microbes (i.e. heterotropic bacteria and cyanobacteria). We suggest that this is a specific biological mechanism for sequestering iron in the mixed layer that developed early in the ocean's history (Archaean period, 2500-3500 million years BP), whereas the more ubiquitous L 2 ligand only arose at the close of the Proterozoic (500-2500 million years BP) when eukaryotic organisms evolved to switch on the ocean's biological pump, allowing L 2 ligands to form from the oxidation of sinking biological particles. This development coincided with the complete oxygenation of the ocean's interior which removed the iron-binding sulfide ion and allowed maintenance of the ocean's iron inventory. These speculations are accompanied by various suggestions about avenues for future research to better understand iron biogeochemistry.

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“…To estimate soluble Fe inputs we used our field data (Section 3.2) and assumed a solubility for dry deposition of 8 % (Baker et al, 2006b) and 14 % for wet deposition Kieber et al (2005) have reported the active photochemical production of soluble Fe(II) and also higher Fe solubilties in N. Atlantic rains, while Halstead et al (2000) report similar solubilities to those of Jickells and Spokes (2001). The solubility of Fe in rainwater is clearly an important uncertainty in these calculations and merits further study.…”

Section: Atmospheric Inputsmentioning

confidence: 99%

Dissolved iron in the vicinity of the Crozet Islands, Southern Ocean

Planquette

Statham

Fones

et al. 2007

Deep Sea Research Part II: Topical Studies in Oceanography

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The annual phytoplankton bloom occurring north of the Crozet Plateau provides a rare opportunity to examine the hypothesis that natural iron fertilisation can alleviate HNLC conditions normally associated with the Southern Ocean. Therefore, during CROZEX, a large multidisciplinary study performed between November 2004 and January 2005, measurements of total dissolved iron (DFe, 0.2 m) were made on seawater from around the islands and atmospheric iron deposition estimated from rain and aerosol samples. waters. Enrichment of dissolved iron (>1 nM) at close proximity to the islands suggests that the plateau and the associated sediments are a source of iron. Waters further north also appear to be affected by this input of coastal and shelf origin, although dissolved iron concentrations decrease as a function of distance to the north of the plateau with a gradient of ~ 0.07 nM.km -1 at the time of sampling. Using lateral and vertical diffusion coefficients derived from Ra isotope profiles and also estimates of atmospheric inputs, it was then possible to estimate a DFe concentration of ~ 0.55 nM to the north of the islands prior to the bloom event, which is sufficient to initiate the bloom, the lateral island source being the largest component. A similar situation is observed for other Sub-Antarctic Islands such as Kerguelen, South Georgia, that supply dissolved iron to their surrounding waters, thus, enhancing chlorophyll concentrations.Keywords: Dissolved Iron, Crozet Islands, Southern Ocean, HNLC. Planquette et al., 26/04/07 3 The hypothesis that iron can act as a limiting micro nutrient in High Nutrient Low Chlorophyll (HNLC hereafter) regions is now generally accepted and has been investigated on a number of occasions (Boyd et al., 2000;de Baar et al., 2005). IntroductionThe iron hypothesis originally proposed by Martin (1990) has led to numerous studies which all demonstrate that the addition of iron to HNLC waters causes an increase in phytoplankton productivity. Subsequent investigations into iron's role in phytoplankton physiology have also revealed important findings. Among them, one can cite its role in photosynthetic and respiratory electron transport, nitrate reduction, and chlorophyll synthesis (Sunda and Huntsman, 1995; Sunda and Huntsman, 1997). The broader implication is that in HNLC waters, the presence of iron can increase the efficiency of the biological pump and promote drawdown of atmospheric carbon dioxide (Bakker et al., 2001;Bakker et al., 2005; Boyd et al., 2004; Law et al., 2006;Martin et al., 1990).The Southern Ocean is subjected to these HNLC conditions and is depicted as the largest potential sink of anthropogenic CO 2 in the global ocean (Martin, 1990; Tréguer and Pondaven, 2001) and as a key system in the context of climate change (Sarmiento et al., 1998). However, due to the existence of distinct regional sub systems differing in their physical and biological properties (Arrigo et al., 1998; Tréguer and Jacques, 1992), this ocean should not be viewed as one entity.Ther...

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Trends in the solubility of iron, aluminium, manganese and phosphorus in aerosol collected over the Atlantic Ocean

Cited by 368 publications

References 42 publications

Atmospheric P deposition to the subtropical North Atlantic: sources, properties, and relationship to N deposition

Atmospheric P deposition to the subtropical North Atlantic: sources, properties, and relationship to N deposition

Iron-binding ligands and their role in the ocean biogeochemistry of iron

Dissolved iron in the vicinity of the Crozet Islands, Southern Ocean

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