Iron isotopes in the Amazon River system: Weathering and transport signatures

Bergquist, Bridget A.; Boyle, E.A.

doi:10.1016/j.epsl.2006.05.004

Cited by 186 publications

(170 citation statements)

References 59 publications

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“…Phytoplankton has shown to fractionate Fe isotopes to a relative high extent. Bergquist and Boyle (2006) measured δ 56 Fe values of -0.24‰ for Amazon plume plankton tows, where they attributed this signature to both intra-and extracellular bound Fe. Additionally, there may be a component of Fe(II) enriched in light Fe, diffusing from the suboxic deeper water and perturbing the δ 56 Fe value of sedimenting material.…”

Section: Biological Processes In the Euphotic Zone And Sinksmentioning

confidence: 99%

“…The filters analyzed in this study were clogged to collect some of the colloidal Fe, which likely consists of the Fe-carbon rich phase and the Fe-oxyhydroxide phase (Lyvén et al, 2003). River water-seawater mixing experiments by Bergquist and Boyle (2006) indicated that aggregated Fe was enriched in heavy isotopes. Hence, aggregation and sedimentation of the oxyhydroxide fraction during estuarine mixing may remove heavy isotopes from surface suspended matter, resulting in a shift towards a more negative isotopic signature in the remaining suspended phase.…”

Section: Fe Sources To the Bothnian Seamentioning

confidence: 99%

“…Beard et al, 2003;Bergquist and Boyle, 2006;de Jong et al, 2007). In particular, significant fractionation of Fe isotopes has been demonstrated during oxidation and reduction reactions, suggesting that Fe isotopes are also useful tracers of Fe redox cycling (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Fractionation of iron species and iron isotopes in the Baltic Sea euphotic zone

Gelting

Breitbarth²,

Stolpe³

et al. 2010

Biogeosciences

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Section: Biological Processes In the Euphotic Zone And Sinksmentioning

confidence: 99%

Section: Fe Sources To the Bothnian Seamentioning

confidence: 99%

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Fractionation of iron species and iron isotopes in the Baltic Sea euphotic zone

Gelting

Breitbarth²,

Stolpe³

et al. 2010

Biogeosciences

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“…Sholkovitz (1978) showed, in an experiment for prediction of metal reactivity in estuarine mixing, that a large fraction (,80%) of river dissolved Fe is lost to the particulate phase because of flocculation in low salinity areas. A recent similar riverine water-seawater mixing study on the Amazon river showed that 88% of the riverine dissolved Fe flocculated at salinity 18 (Bergquist and Boyle 2006). Kremling (1983) and Statham and Burton (1986) Open circles correspond to the sampling sites of TS2006, COCA (eastern Atlantic) and MP (western Atlantic).…”

mentioning

confidence: 99%

“…Other possible metal sources for phytoplankton, such as shelf pore water, sediments, or upwelling (Fitzwater et al 2003;Aguilar-Islas and Bruland 2006;Bergquist and Boyle 2006), could have been considered here so that the data in TS2006 would have been enclosed within the polygon described by the end members. Additionally, the metal concentrations for Trichodesmium and aerosol reported in the TS2006 web appendix do not fit the Fe : Al and Mn : Al molar ratio values used to visualize the assumed end members (dust or river as sources for phytoplankton; fig.…”

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confidence: 99%

Influence of river discharge in the tropical and subtropical North Atlantic Ocean

Cunha

Croot

LaRoche

2009

Limnology & Oceanography

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Influence of river discharge in the tropical and subtropical North Atlantic OceanThe recent article by Tovar-Sanchez et al. (2006; hereafter referred to as TS2006), presents a new comprehensive dataset of trace metal concentrations in Trichodesmium sp. populations and aerosol samples from the western tropical (MP01, MP03, and MP08 samples) and eastern subtropical (COCA2 samples) Atlantic Ocean. In TS2006, the authors considered the atmospheric deposition of Saharan dust as probably the main source of trace metals for the surface tropical Atlantic, together with the riverine input of trace metals to the coastal ocean. TS2006 determined the trace metal composition in aerosol samples and Trichodesmium sp. colonies in both the eastern and the western tropical Atlantic, and used additional published data for riverine upstream concentrations of dissolved and particulate trace metals. The riverine and aerosol metal ratios were used to infer the sources of these metals in Trichodesmium sp. colonies in the tropical and subtropical Atlantic Ocean. TS2006 found that trace metal ratios measured in some samples of Trichodesmium sp. colonies (Mn : Al and Fe : Al) were more similar to the dissolved riverine trace metal ratios than to the aerosol metal composition, and concluded that the Amazon and Niger Rivers are seasonally the most important sources of trace metals for Trichodesmium sp.Although the new data presented in TS2006 are relevant for the characterization of metal composition in aerosol and phytoplankton, we present here seven fundamental points explaining why we fundamentally disagree with their conclusions.

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Geochemistry of the Cambrian Sirius Passet Lagerstätte, Northern Greenland

Boudec

Ineson

Rosing

et al. 2014

Geochem. Geophys. Geosyst.

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The lower Cambrian Sirius Passet Lagerst€ atte (518 Ma) consists of mudstones about 8 m thick located in the Franklinian Basin of North Greenland. We analyzed major and trace elements plus the S, C, Cu, Fe, Zn, and Mo isotope compositions. Factor analysis allowed the lithology of the mudstone to be broken down into variable proportions of two inputs, a dry felsic component and a hydrous mafic component (smectite or chlorite). Zircons U-Pb ages indicate multiple sources, the local Proterozoic basement of Northern Greenland (1250-2400 Ma) and Pan-African felsic magmas (620-650 Ma) from across the Iapetus ocean. Diagenesis involved the reduction of Fe, S, and Mo from seawater and pyritization. The Sirius Passet Lagerst€ atte formed in oxygen-starved muds inhibiting degradation of organic matter underneath a wellventilated water column. The chemistry of the samples, their very fine grain size, their apparent lack of graded bedding, and the age of zircons suggest that the Lagerst€ atte may represent wind-blown dust deposited on the continental slope.

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Iron isotopes in the Amazon River system: Weathering and transport signatures

Cited by 186 publications

References 59 publications

Fractionation of iron species and iron isotopes in the Baltic Sea euphotic zone

Fractionation of iron species and iron isotopes in the Baltic Sea euphotic zone

Influence of river discharge in the tropical and subtropical North Atlantic Ocean

Geochemistry of the Cambrian Sirius Passet Lagerstätte, Northern Greenland

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