Spatial and Temporal Trends in Mineral Dust Provenance in the South Pacific—Evidence From Mixing Models

Longman, Jack; Struve, Torben; Pahnke, Katharina

doi:10.1029/2021pa004356

Cited by 13 publications

(16 citation statements)

References 84 publications

(203 reference statements)

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“…Recognizing that air pollution inherently represents a mixture of sources, we wanted to quantify the contributions of Pb from coal-burning and non-ferrous metal smelting to the calculated pollution end-member as these two sources represent the main contributors of Pb emissions following the phase-out of leaded gasoline in China. We used MixSIAR, an advanced Bayesian isotope mixing model, − to quantify the contributions of Pb from Chinese ore and coal sources to our calculated pollution end-member (see the SI). The end-member values are defined as the mean ± 1σ of the published data for each source (Table S1, Figure and Figure S5).…”

Section: Resultsmentioning

confidence: 99%

Provenance of Anthropogenic Pb and Atmospheric Dust to Northwestern North America

Koffman

Saylor

Zhong

et al. 2022

Environ. Sci. Technol.

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Industrial activities release aerosols containing toxic metals into the atmosphere, where they are transported far from their sources, impacting ecosystems and human health. Concomitantly, long-range-transported mineral dust aerosols play a role in Earth’s radiative balance and supply micronutrients to iron-limited ecosystems. To evaluate the sources of dust and pollutant aerosols to Alaska following the 2001 phase-out of leaded gasoline in China, we measured Pb-Sr-Nd isotopic compositions of particles collected in 2016 from snow pits across an elevational transect (2180–5240 m-a.s.l) in Denali National Park, USA. We also determined Pb flux and enrichment from 1991–2011 in the Denali ice core (3870 m-a.s.l). Chinese coal-burning and non-ferrous metal smelting account for up to 64% of Pb deposition at our sites, a value consistent across the western Arctic. Pb isotope ratios in the aerosols did not change between 2001 and 2016, despite the ban on lead additives. Emissions estimates demonstrate that industrial activities have more than compensated for the phase-out of leaded gasoline, with China emitting ∼37,000 metric tons year –1 of Pb during 2013–2015, approximately 78% of the Pb from East Asia. The Pb flux to Alaska now equals that measured in southern Greenland during peak pollution from North America.

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Section: Resultsmentioning

confidence: 99%

Provenance of Anthropogenic Pb and Atmospheric Dust to Northwestern North America

Koffman

Saylor

Zhong

et al. 2022

Environ. Sci. Technol.

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“…For this reason, previous dust provenance work in the South Pacific focused on tracers that are typically less sensitive to grain size effects, e.g., Nd and Pb isotopes ( 51 ). Recent tests with different mixing model configurations demonstrate that source apportionment in the dust fraction of South Pacific marine sediments shows only modest changes between setups with and without Sr isotopes ( 52 ). However, our data show a considerable 87 Sr/ 86 Sr change of ∼0.005 coinciding with an ε Nd excursion of ∼2 between ∼70,000 and 40,000 y BP ( Fig.…”

Section: Resultsmentioning

confidence: 99%

“…As airborne dust particle size is controlled primarily by gravitational settling ( 2 , 49 ), these differences were suggested to result from changes in dust sources, namely, wind and transport patterns specific to the different sectors of the Southern Ocean ( 48 ). Recent provenance studies support a more nuanced picture of dust sources and transport routes in the Southern Hemisphere during glacial and interglacial periods ( 36 , 50 – 52 ).…”

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confidence: 92%

“…South American dust PSAs are grouped by latitude. Key locations included in the discussion are as follows: Antarctic ice core EPICA Dome C ( 68 , 103 ), Atlantic Ocean cores TN057-06 ( 16 ) and ODP1090 ( 12 , 13 ), South Pacific core PS75/056-1 ( 15 , 16 , 48 ), Chile margin cores GeoB3375-1 and GeoB15016 ( 41 ), and South Pacific LGM dust provenance time slice cores (black dots) ( 51 , 52 ). STF, Subtropical Front; SAF, Subantarctic Front; PF, Polar Front; SB, Southern Boundary of the Antarctic Circumpolar Current; PFZ, Polar Frontal Zone.…”

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confidence: 99%

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Systematic changes in circumpolar dust transport to the Subantarctic Pacific Ocean over the last two glacial cycles

Struve

Longman

Zander

et al. 2022

Proc. Natl. Acad. Sci. U.S.A.

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The input of the soluble micronutrients iron (Fe) and/or manganese (Mn) by mineral dust stimulates net primary productivity in the Fe/Mn-deficient Southern Ocean. This mechanism is thought to increase carbon export, thus reducing atmospheric CO 2 during the Pleistocene glacial cycles. Yet, relatively little is known about changes in the sources and transport pathways of Southern Hemisphere dust over glacial cycles. Here, we use the geochemical fingerprint of the dust fraction in marine sediments and multiisotope mixture modeling to identify changes in dust transport to the South Pacific Subantarctic Zone (SAZ). Our data show that dust from South America dominated the South Pacific SAZ during most of the last 260,000 a with maximum contributions of up to ∼70% in the early part of the glacial cycles. The enhanced dust-Fe fluxes of the latter parts of the glacial cycles show increased contributions from Australia and New Zealand, but South American dust remains the dominant component. The systematic changes in dust provenance correspond with grain size variations, consistent with the circumpolar transport of dust by the westerly winds. Maximum contributions of dust from more proximal sources in Australia and New Zealand (up to ∼63%) paired with a finer dust grain size indicate reduced westerly wind speeds over the South Pacific SAZ during deglacial and peak interglacial intervals. These quantitative dust provenance changes provide source-specific dust-Fe fluxes in the South Pacific SAZ and show how their systematic changes in magnitude and timing influence the Southern Ocean dust-Fe feedback on glacial-interglacial to millennial time scales.

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“…MixSIAR is a Bayesian mixing model developed for use in stable isotope studies (Stock et al., 2018; Stock & Semmens, 2016). By considering the dust compositions in aerosol samples as mixtures and the isotopic signatures of North African PSAs as sources, MixSIAR is able to estimate the mixture of dust from different North African PSAs that satisfy isotopic mass balance in our dust samples (Longman et al., 2022; see Figure S1 in Supporting Information ). Through incorporating standard deviations of the sources, the model considers variation in the isotopic signature of PSAs when considering likely model fits.…”

Section: Methodsmentioning

confidence: 99%

Interannual Variability in the Source Location of North African Dust Transported to the Amazon

Barkley

Pourmand

Longman

et al. 2022

Geophysical Research Letters

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Aeolian dust is produced perennially across numerous potential source areas (PSAs) in North Africa, and it is transported to the Amazon and western Tropical Atlantic Ocean (TAO) in boreal winter and spring (Prospero et al., 1981). Transported dust is thought to alleviate nutrient limitations in the TAO and Amazon Basin, fueling net primary productivity and sequestering carbon dioxide into the biosphere. Because the source location of dust controls the magnitude, mineralogy, and solubility-a proxy for bioavailability-of associated nutrients such as phosphorus (P) and iron (Fe), it is important to identify the PSA(s) of transported dust (

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Spatial and Temporal Trends in Mineral Dust Provenance in the South Pacific—Evidence From Mixing Models

Abstract: Nutrients delivered to the marine environment by dust may play a key role in regulating biogeochemical cycles, in particular in remote ocean areas where nutrients may otherwise be limited (

Cited by 13 publications

References 84 publications

Provenance of Anthropogenic Pb and Atmospheric Dust to Northwestern North America

Provenance of Anthropogenic Pb and Atmospheric Dust to Northwestern North America

Systematic changes in circumpolar dust transport to the Subantarctic Pacific Ocean over the last two glacial cycles

Interannual Variability in the Source Location of North African Dust Transported to the Amazon

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