Anthropogenic Signatures of Lead in the Northeast Atlantic

Rusiecka, Dagmara; Gledhill, Martha; Milne, Angela; Achterberg, Eric P.; Annett, Amber; Atkinson, Sov; Birchill, Antony J.; Karstensen, Johannes; Lohan, Maeve C.; Mariez, Clarisse; Middag, Rob; Rolison, John M.; Tanhua, Toste; Ussher, Simon J.; Connelly, Douglas P.

doi:10.1002/2017gl076825

Cited by 31 publications

(40 citation statements)

References 70 publications

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“…(SI , Table S3). While DPb and DAl distributions are known to be influenced by atmospheric inputs, sediment supply, and scavenging Menzel Barraqueta et al, 2019;Rusiecka et al, 2018), an association of Al with diatom frustules (Menzel Barraqueta et al, 2018), and Pb with organic matter remineralization and sediment supply (Rusiecka et al, 2018)…”

Section: 1029/2020gb006674mentioning

confidence: 99%

“…In recent years, large new data sets have emerged as part of the international GEOTRACES program (Henderson et al, 2007;Schlitzer et al, 2018). The availability of oceanic Fe data has substantially improved (e.g., Fitzsimmons et al, 2017;Milne et al, 2017;Tagliabue et al, 2012), with also some new data sets for, for example, Zn (Middag et al, 2019;Wyatt et al, 2014), Al (Measures et al, 2015;Menzel Barraqueta et al, 2018), Pb (Noble et al, 2015;Rusiecka et al, 2018), Cd (Middag et al, 2018;Wu & Roshan, 2015), and Ni (Middag et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

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Trace Element Biogeochemistry in the High‐Latitude North Atlantic Ocean: Seasonal Variations and Volcanic Inputs

Achterberg

Steigenberger

Klar

et al. 2021

Global Biogeochemical Cycles

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We present dissolved and total dissolvable trace elements for spring and summer cruises in 2010 in the high-latitude North Atlantic. Surface and full depth data are provided for Al, Cd, Co, Cu, Mn, Ni, Pb, and Zn in the Iceland and Irminger Basins, and consequences of biological uptake and inputs by the spring Eyjafjallajökull volcanic eruption are assessed. Ash from Eyjafjallajökull resulted in pronounced increases in Al, Mn, and Zn in surface waters in close proximity to Iceland during the eruption, while 3 months later during the summer cruise levels had returned to more typical values for the region. The apparent seasonal removal ratios of surface trace elements were consistent with biological export. Assessment of supply of trace elements to the surface mixed layer for the region, excluding volcanic inputs, indicated that deep winter mixing was the dominant source, with diffusive mixing being a minor source (between 13.5% [dissolved Cd, DCd] and −2.43% [DZn] of deep winter flux), and atmospheric inputs being an important source only for DAl and DZn (DAl up to 42% and DZn up to 4.2% of deep winter + diffusive fluxes) and typically less than 1% for the other elements. Elemental supply ratios to the surface mixed layer through convection were comparable to apparent removal ratios we calculated between spring and summer. Given that deep mixing dominated nutrient and trace element supply to surface waters, predicted increases in water column stratification in this region may reduce supply, with potential consequences for primary production and the biological carbon pump.

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Section: 1029/2020gb006674mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Trace Element Biogeochemistry in the High‐Latitude North Atlantic Ocean: Seasonal Variations and Volcanic Inputs

Achterberg

Steigenberger

Klar

et al. 2021

Global Biogeochemical Cycles

Self Cite

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“…The concentration range and depth distribution is similar to reported distributions further offshore at about 21°W (Noble et al, 2015). These authors suggested that increased concentrations of up to 70 pmol L -1 between 600 and 800 m depth were related to the influence of (Rusiecka et al, 2018). The major source of Pb to the ocean is atmospheric dust deposition from anthropogenic emissions (Bridgestock et al, 2016;Nriagu and Pacyna, 1988;Veron et al, 1994) with a recent indication of reduced anthropogenic Pb inputs to surface waters in the eastern tropical Atlantic under the North African dust plume (Bridgestock et al, 2016).…”

Section: Spatial Distributions Of Dissolved and Leachable Particulatementioning

confidence: 99%

Controls on redox-sensitive trace metals in the Mauritanian oxygen minimum zone

Rapp¹,

Schlösser²,

Barraqueta³

et al. 2018

Preprint

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Abstract. The availability of the micronutrient iron (Fe) in surface waters determines primary production, N2 fixation and microbial community structure in large parts of the world's ocean, and thus plays an important role in ocean carbon and nitrogen cycles. Eastern boundary upwelling systems and the connected oxygen minimum zones (OMZs) are typically associated with elevated concentrations of redox-sensitive trace metals (e.g. Fe, manganese (Mn) and cobalt (Co)), with shelf sediments typically forming a key source. Over the last five decades, an expansion and intensification of OMZs has been observed and this trend is likely to proceed. However, it is unclear how trace metal (TM) distributions and transport are influenced by decreasing oxygen (O2) concentrations. Here we present dissolved (d; <&#8201;0.2&#8201;&#956;m) and leachable particulate (Lp; >&#8201;0.2&#8201;&#956;m) TM data collected at 7 stations along a 50&#8201;km transect in the Mauritanian shelf region. We observed enhanced concentrations of Fe, Co and Mn corresponding with low O2 concentrations (<&#8201;50&#8201;&#956;mol&#8201;kg&#8722;1), which were decoupled from major nutrients and nutrient-like and scavenged TMs (cadmium (Cd), lead (Pb), nickel (Ni) and copper (Cu)). Additionally, data from repeated station occupations indicated a direct link between dissolved and leachable particulate Fe, Co, Mn, and O2. An observed dFe decrease from 10 to 5&#8201;nmol&#8201;L&#8722;1 coincided with an O2 increase from 30 to 50&#8201;&#956;mol&#8201;kg&#8722;1 and with a concomitant decrease in turbidity. The changes in Fe (Co and Mn) were likely driven by variations in their release from sediment pore water, facilitated by lower O2 concentrations and longer residence time of the water mass on the shelf. Variations in organic matter remineralization and lithogenic inputs (atmospheric deposition or sediment resuspension) only played a minor role in redox-sensitive TM variability. Vertical dFe fluxes from O2-depleted subsurface to surface waters (0.08&#8211;13.5&#8201;&#956;mol&#8201;m&#8722;2&#8201;d&#8722;1) were driven by turbulent mixing and vertical advection, and were an order of magnitude larger than atmospheric deposition fluxes (0.63&#8211;1.43&#8201;&#956;mol&#8201;m&#8722;2&#8201;d&#8722;1). Benthic fluxes are therefore the dominant dFe supply to surface waters on the continental margins of the Mauritanian upwelling region. Overall, our results indicated that the projected future decrease in O2 concentrations in OMZs may result in increases in Fe, Mn and Co concentrations.

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“…Ideally, a study such as that performed by Du et al () for Nd isotopes would allow for the quantification of porewater control on the archived Pb signal. Unfortunately, core top sediments integrate over decades to centuries, while anthropogenic Pb inputs varied considerably over these time scales: increasing with the onset of industrial activity and the use of leaded gasoline and more recently decreasing with the implementation of environmental regulation and phasing out of leaded gasoline (Rusiecka et al, ). This is particularly true for the Mediterranean as it experiences a larger human impact by volume relative to the Atlantic or Pacific.…”

Section: Resultsmentioning

confidence: 99%

Precessional Cyclicity of Seawater Pb Isotopes in the Late Miocene Mediterranean

Modestou

Gutjahr

Schee

et al. 2019

Paleoceanog and Paleoclimatol

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Astronomical tuning in the Mediterranean region is primarily based on organically-mediated proxies, such as cyclicity of organic rich layers or changes in foraminiferal assemblages. Both during and post deposition, organic proxies can be affected by complex processes not immediately related to the changes in precession (insolation) they are assumed to reflect. Here we present an isotopic proxy which exhibits precessional cyclicity yet is inorganic. Seawater lead (Pb) isotope records over four precessional cycles between 6.6 and 6.5 Ma, from bulk sediment leachates of three Messinian, circum-Mediterranean marginal locations, show variations consistent with precessional cyclicity. During insolation minima, the Pb isotope signatures from all three sites converge to similar values, suggesting a regional process is affecting all three locations at that time. Data from the marginal sites are compared with new data from ODP Site 978 and published data from a variety of geological archives from the Mediterranean region to determine the mechanism(s) causing the observed variability. While the comparisons are not fully conclusive, the timing of events suggest that increased dust production from North Africa during insolation minima is the most likely control. This hypothesis implies that authigenic marine Pb isotope records have the potential to provide a reliable inorganic tie point for Mediterranean cyclostratigraphy where sub-precessional resolution is required. An inorganic tie point could also provide the means to resolve long-standing problems in Mediterranean stratigraphy on precessional and sub-precessional timescales which have been obscured due to post-depositional changes (e.g., sapropel burn-down) or suboptimal ecological conditions (e.g., the Messinian Salinity Crisis). Plain Language SummaryResearch into the geological and climate history of the Mediterranean region has been important globally, partly because the geologic timescale, back to about 23 million years ago, is pinned to the geological record of this region and partly because the water exiting the Mediterranean into the Atlantic is an important component of global ocean circulation. In this paper, we examine changes through time in the isotope ratios of the trace metal lead (Pb), which is present in tiny amounts even in unpolluted seawater. Our Pb isotope records, covering~100 thousand years at about 6.5 million years ago, show distinctive regular cyclicity with time, with "peaks" at approximately 20 thousand year intervals. We hypothesize that wet-dry climate cycles in North Africa produced these peaks by supplying more dust to the Mediterranean during the driest part of the cycle, when Pb from dust would have more strongly influenced the seawater Pb isotope composition. This hypothesis is exciting because it suggests that seawater Pb isotopes have the potential to improve our understanding of the passage of time in the Mediterranean region, in particular at times and locations where existing techniques are inadequate.

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Anthropogenic Signatures of Lead in the Northeast Atlantic

Cited by 31 publications

References 70 publications

Trace Element Biogeochemistry in the High‐Latitude North Atlantic Ocean: Seasonal Variations and Volcanic Inputs

Trace Element Biogeochemistry in the High‐Latitude North Atlantic Ocean: Seasonal Variations and Volcanic Inputs

Controls on redox-sensitive trace metals in the Mauritanian oxygen minimum zone

Precessional Cyclicity of Seawater Pb Isotopes in the Late Miocene Mediterranean

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