Rapid mineral surface weathering beneath the Greenland Ice Sheet shown by radium and uranium isotopes

Linhoff, B.; Charette, M. A.; Wadham, Jemma L.

doi:10.1016/j.chemgeo.2020.119663

Cited by 8 publications

(4 citation statements)

References 79 publications

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“… 28 ). With the discharge-averaged concentrations found in subglacial runoff of the Leverett Glacier in western Greenland 49 this would, after mixing in the cavity, cause increases of only 0.03 dpm/m 3 226 Ra and 0.35 dpm/m 3 228 Ra in the cavity outflow, negligible compared to the observed signals at 125 m. We conclude that the radium is sedimentary in origin, either emerging from the seafloor or from sediments entrained within the ice-tongue and released into the water column by basal melting.…”

Section: Resultsmentioning

confidence: 99%

The 79°N Glacier cavity modulates subglacial iron export to the NE Greenland Shelf

et al. 2021

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Approximately half of the freshwater discharged from the Greenland and Antarctic Ice Sheets enters the ocean subsurface as a result of basal ice melt, or runoff draining via the grounding line of a deep ice shelf or marine-terminating glacier. Around Antarctica and parts of northern Greenland, this freshwater then experiences prolonged residence times in large cavities beneath floating ice tongues. Due to the inaccessibility of these cavities, it is unclear how they moderate the freshwater associated supply of nutrients such as iron (Fe) to the ocean. Here, we show that subglacial dissolved Fe export from Nioghalvfjerdsbrae (the ‘79°N Glacier’) is decoupled from particulate inputs including freshwater Fe supply, likely due to the prolonged ~162-day residence time of Atlantic water beneath Greenland’s largest floating ice-tongue. Our findings indicate that the overturning rate and particle-dissolved phase exchanges in ice cavities exert a dominant control on subglacial nutrient supply to shelf regions.

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Section: Resultsmentioning

confidence: 99%

The 79°N Glacier cavity modulates subglacial iron export to the NE Greenland Shelf

et al. 2021

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“…In mountainous environments, different slope orientations have different weathering rates due to the differences in humidity 22 ; glaciers have strong physical and chemical weathering 23 . In previous studies, a variety of isotopes have been used to prove that the chemical weathering input of glacial melt water cannot be ignored and has important global carbon cycle significance 24 , 25 . Human activities are also an important factor affecting rock weathering, especially the karst environment which is fragile 26 , 27 and prone to quick penetration from pollutants such as domestic sewage and agricultural fertilizers 28 , 29 .…”

Section: Introductionmentioning

confidence: 99%

New estimate of chemical weathering rate in Xijiang River Basin based on multi-model

Yong¹,

Shi²,

He³

et al. 2021

Sci Rep

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Hydrochemistry and Sr isotope compositions were measured in water samples collected during high- and low-water periods from the main stream and tributaries of the Xijiang River Basin in southern China. The primary weathering end-members were analyzed and calculated using the multi-model combination and classic hydrogeochemical method. During the high-water period, structural factors were found to be the main factors controlling chemical weathering in the basin, whereas anthropogenic activity and other random factors had a negligible influence. During the low-water period, both structural and random factors controlled chemical weathering. Through path-model and semi-variance analyses, we determined and quantified the relationship between the main weathering sources, whose results were stable; this is consistent with the inversion model. The total dissolved substances were mainly derived from carbonate weathering, which was approximately 76% (0–96%) while silicate weathering accounted for only 14% (5–19%). The inversion model results showed that the optimum silicate weathering rate was 7.264–35.551 × 103 mol/km2/year, where carbonic acid was the main factor that induces weathering. The CO2 flux consumed by rock weathering in the basin during the study period was 150.69 × 109 mol/year, while the CO2 flux consumed by carbonic acid weathering of carbonate (CCW) and silicate rocks (CSW) was 144.47 and 29.45 × 109 mol/year, respectively. The CO2 flux produced by H2SO4 weathered carbonate (SCW) was 23.23 × 109 mol/year.

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“…The dissolved Ra activities in the Kuparuk River and Putuligayuk River were similar, with No Point Creek (reported as runoff) having slightly higher values (Table 1). Most Arctic rivers have not been sampled for short‐lived isotopes; however, 226 Ra activities measured in this study ranged between 1.4 and 3.9 dpm 100 L −1 , which are lower than those seen in large Arctic rivers such as the Yenisey and Lena Rivers in Siberia (Rutgers van der Loeff et al 2003), or the Mackenzie and Yukon Rivers in North America (Kipp et al 2020), but are comparable to activities seen in similarly sized Arctic rivers such as the Ellice River, rivers near Anchorage, AK (Bullock et al 2022), and rivers in Greenland (Linhoff et al 2020).…”

Section: Resultsmentioning

confidence: 90%

“…Lagoon surface, river, and ocean Ra activities across seasons for (a) 224 Ra, (b) 223 Ra, (c) 228 Ra, and (d) 226 Ra. (Rutgers van der Loeff et al 2003), or the Mackenzie and Yukon Rivers in North America (Kipp et al 2020), but are comparable to activities seen in similarly sized Arctic rivers such as the Ellice River, rivers near Anchorage, AK (Bullock et al 2022), and rivers in Greenland (Linhoff et al 2020).…”

Section: River Ra Activitiesmentioning

confidence: 93%

Seasonality of submarine groundwater discharge to an Arctic coastal lagoon

Bullock,

Schaal,

Cardenas

et al. 2024

Limnology & Oceanography

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Supra‐permafrost submarine groundwater discharge (SGD) in the Arctic is potentially important for coastal biogeochemistry and will likely increase over the coming decades owing to climate change. Despite this, land‐to‐ocean material fluxes via SGD in Arctic environments have seldom been quantified. This study used radium (Ra) isotopes to quantify SGD fluxes to an Arctic coastal lagoon (Simpson Lagoon, Alaska) during five sampling periods between 2021 and 2023. Using a Ra mass balance model, we found that the SGD water flux was substantial and dependent on environmental conditions. No measurable SGD was detected during the spring sampling period (June 2022), when the lagoon was partially ice‐covered. During ice‐free periods, the main driver of SGD in this location is wind‐driven lagoon water level changes, not tides, which control surface water recirculation through sediments along the lagoon boundary. A combination of wind strength and direction led to low SGD fluxes in July 2022, with an SGD flux of (6 ± 3) × 106 m3 d−1, moderate fluxes in August 2021 and July 2023, which had an average flux of (17 ± 9) × 106 m3 d−1, and high fluxes in October 2022, at (79 ± 16) × 106 m3 d−1. This work demonstrates how soil and environmental conditions in the Arctic impact Ra mobilization, laying a foundation for future SGD studies in the Arctic and shedding light on the major processes driving Ra fluxes in this important environment.

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Rapid mineral surface weathering beneath the Greenland Ice Sheet shown by radium and uranium isotopes

Cited by 8 publications

References 79 publications

The 79°N Glacier cavity modulates subglacial iron export to the NE Greenland Shelf

The 79°N Glacier cavity modulates subglacial iron export to the NE Greenland Shelf

New estimate of chemical weathering rate in Xijiang River Basin based on multi-model

Seasonality of submarine groundwater discharge to an Arctic coastal lagoon

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