Estimation of atmospheric nutrient inputs to the Atlantic Ocean from 50°N to 50°S based on large‐scale field sampling: Iron and other dust‐associated elements

Baker, Alex R.; Adams, Christopher; Bell, Thomas G.; Jickells, Timothy D.; Ganzeveld, L.

doi:10.1002/gbc.20062

Cited by 103 publications

(144 citation statements)

References 67 publications

(121 reference statements)

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“…In contrast to N, dry deposition of s-Fe during M91 was 1-2 (for sample TM09) orders of magnitude higher than reported for the remote South Atlantic (2-7 nmol m −2 d −1 ; Baker et al, 2013). Our average estimate of F d s-Fe during M91 (45 nmol m −2 d −1 , equivalent to ∼ 0.9 mg m −2 yr −1 ) appears to be somewhat higher than the total deposition flux of s-Fe (0.3 mg m −2 yr −1 ) estimated for the region by Krishnamurthy et al (2009;as reported by Messie and Chavez, 2015).…”

Section: Biogeosciencescontrasting

confidence: 53%

Soluble trace metals in aerosols over the tropical south-east Pacific offshore of Peru

et al. 2016

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Abstract. Bulk aerosol samples collected during cruise M91 of FS Meteor off the coast of Peru in December 2012 were analysed for their soluble trace metal (Fe, Al, Mn, Ti, Zn, V, Ni, Cu, Co, Cd, Pb, Th) and major ion (including NO − 3 and NH + 4 ) content. These data are among the first recorded for trace metals in this relatively poorly studied region of the global marine atmosphere. To the north of ∼ 13 • S, the concentrations of several elements (Fe, Ti, Zn, V, Ni, Pb) appear to be related to distance from the coast. At the south of the transect (∼ 15-16 • S), elevated concentrations of Fe, Cu, Co, and Ni were observed, and we calculated dry deposition fluxes of soluble Cu approximately an order of magnitude higher than a recent model-based estimate of total Cu deposition to the region. The model did not take account of emissions from the large smelting facilities in the south of Peru and northern Chile, and our results may indicate that these facilities constitute an important source of trace metals to the region. Calculated dry deposition fluxes (3370-17800 and 16-107 nmol m −2 d −1 for inorganic nitrogen and soluble Fe respectively) indicated that atmospheric input to the waters of the Peru upwelling system contains an excess of Fe over N, with respect to phytoplankton requirements. This may be significant as primary production in these waters has been reported to be limited by Fe availability, but atmospheric deposition is unlikely to be the dominant source of Fe to the system.

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Section: Biogeosciencescontrasting

confidence: 53%

Soluble trace metals in aerosols over the tropical south-east Pacific offshore of Peru

et al. 2016

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“…A local peak in chl:C phyto was also present just north of the equator at ~15° N in the ITCZ. Nutrient inputs into the ITCZ include upwelling (Robinson et al 2006) and nitrogen and ironrich dust blowing off the African continent, which peak in concentration in this region (Baker et al 2013). Samples from the ITCZ create a cluster of points (Fig.…”

Section: Discussionmentioning

confidence: 99%

Photoacclimation of natural phytoplankton communities

Graff

Westberry²,

Milligan³

et al. 2016

Mar. Ecol. Prog. Ser.

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Phytoplankton regulate internal pigment concentrations in response to light and nutrient availability. Chlorophyll a to phytoplankton carbon ratios (chl:C phyto ) are commonly reported as a function of growth irradiance (E g ) for evaluating the photoacclimation response of phytoplankton. In contrast to most culture experiments, natural phytoplankton communities experience fluctuating environmental conditions, making it difficult to compare field and lab observations. Observing and understanding photoacclimation in nature is important for deciphering changes in chl:C phyto resulting from environmental forcings and for accurately estimating net primary production (NPP) in models which rely on a parameterized description of photoacclimation. Here we employ direct analytical measurements of C phyto and parallel high-resolution biomass estimates from particulate backscattering (b bp ) and flow cytometry to investigate chl:C phyto in natural phytoplankton communities. Chl:C phyto observed over a wide range of E g in the field was consistent with photoacclimation responses inferred from satellite observations. Field-based photoacclimation observations for a mixed natural community contrast with laboratory results for single species grown in continuous light and nutrient-replete conditions. Applying a carbon-based NPP model to our field data for a north−south transect in the Atlantic Ocean results in estimates that closely match 14 C depth-integrated NPP for the same cruise and with historical records for the distinct biogeographic regions of the Atlantic Ocean. Our results are consistent with previous satellite and model observations of cells growing in natural or fluctuating light and showcase how direct measurements of C phyto can be applied to explore phytoplankton photophysiology, growth rates, and production at high spatial resolution in situ.

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“…9) caused by P concentrations that ranged between 0.17 and 0.28 µmol kg −1 and exceeded N concentrations, resulting in surface water N* deficits. The very low N concentrations further suggest that atmospheric deposition that is assumed to be another significant N source to the ocean (Duce et al, 2008;Baker et al, 2013) is negligible. However, Sohm et al (2011) observed N 2 fixation within the ABFZ (∼ 13-15 • S) coinciding with decreased thermocline δ 15 N − NO 3 values and elevated dissolved Fe and cobalt surface concentrations (Noble et al, 2012), which are important micronutrients for marine diazotrophic cyanobacteria (Saito et al, 2002(Saito et al, , 2004.…”

Section: Spatial and Temporal Variabilitymentioning

confidence: 98%

Spatio-temporal patterns of C : N : P ratios in the northern Benguela upwelling system

Flohr

Plas²,

Emeis

et al. 2014

Biogeosciences

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Abstract. On a global scale the ratio of fixed nitrogen (N) and phosphate (P) is characterized by a deficit of N with regard to the classical Redfield ratio of N : P = 16 : 1 reflecting the impact of N loss occurring in the oceanic oxygen minimum zones. The northern Benguela upwelling system (NBUS) is known for losses of N and the accumulation of P in sub-and anoxic bottom waters and sediments of the Namibian shelf resulting in low N : P ratios in the water column. To study the impact of the N : P anomalies on the regional carbon cycle and their consequences for the export of nutrients from the NBUS into the oligotrophic subtropical gyre of the South Atlantic, we measured dissolved inorganic carbon (C T ), total alkalinity (A T ), oxygen (O 2 ) and nutrient concentrations in February 2011. The results indicate increased P concentrations over the Namibian shelf due to P efflux from sediments resulting in a C : N : P : -O 2 ratio of 106 : 16 : 1.6 : 138. N reduction further increase C : N and reduce N : P ratios in those regions where O 2 concentrations in bottom waters are < 20 µmol kg −1 . However, off the shelf along the continental margin, the mean C : N : P : -O 2 ratio is again close to the Redfield stoichiometry. Additional nutrient data measured during two cruises in 2008 and 2009 imply that the amount of excess P, which is created in the bottom waters on the shelf, and its export into the subtropical gyre after upwelling varies through time. The results further reveal an inter-annual variability of excess N within the South Atlantic Central Water (SACW) that flows from the north into the NBUS, with highest N values observed in 2008. It is postulated that the N excess in SACW occurred due to the impact of remineralized organic matter produced by N 2 fixation and that the magnitude of excess P formation and its export is governed by inputs of excess N along with SACW flowing into the NBUS. Factors controlling N 2 fixation north of the BUS need to be addressed in future studies to better understand the role of the NBUS as a P source and N sink in the coupled C : N : P cycles.

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Estimation of atmospheric nutrient inputs to the Atlantic Ocean from 50°N to 50°S based on large‐scale field sampling: Iron and other dust‐associated elements

Cited by 103 publications

References 67 publications

Soluble trace metals in aerosols over the tropical south-east Pacific offshore of Peru

Soluble trace metals in aerosols over the tropical south-east Pacific offshore of Peru

Photoacclimation of natural phytoplankton communities

Spatio-temporal patterns of C : N : P ratios in the northern Benguela upwelling system

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