Chemical weathering in a moraine at the ice sheet margin at Kangerlussuaq, western Greenland

Auqué, Luis F.; Puigdomènech, I.; Tullborg, Eva‐Lena; Gimeno, M. Concepción; Grodzinsky, K.; Högmalm, Johan

doi:10.1080/15230430.2019.1660125

Cited by 12 publications

(15 citation statements)

References 87 publications

(161 reference statements)

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“…Thus, a geogenic source is more likely. In the Alpine region, dissolved SO 4 originates mainly from dissolution of gypsum (CaSO 4 •2H 2 O) and/or anhydrite (CaSO 4 ) and from oxidative dissolution of sulfide-bearing minerals (e.g., pyrite) (Dubois et al 1993;Pastorelli et al 2001;Strauss et al 2015;Vuataz 1982 dissolution of gypsum/anhydrite or oxidation of sulfide coupled to weathering of calcium silicates (Auqué et al 2019;Stachnik et al 2016;Tranter et al 2002). The position of I3, I4 (the inlets most influenced by the rock glacier) and I5 in the Piper Diagram (Fig.…”

Section: Discussionmentioning

confidence: 99%

Climate Change-Induced Changes in the Chemistry of a High-Altitude Mountain Lake in the Central Alps

Steingruber

Bernasconi

Valenti³

2020

Aquat Geochem

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Mountains are among the most sensitive ecosystems to climate change, and one of the most evident signs of climate-related effect is the continuous net loss of ice from the cryosphere. Several studies showed that meltwater from glaciated and perennially frozen areas can profoundly affect alpine aquatic ecosystems. Here, we present the impressive temporal increase in solutes in Lake Leit, a mountain lake in the Central Alps that is impacted by an active rock glacier. During the last 30 years, concentrations of sulfate and base cations increased by factors of 4 and 3, respectively. Atmospheric deposition, the only catchment external source, could be excluded as possible cause. The inlets have sulfate and base cations concentrations that were up to double the concentrations of the lake outlet confirming the presence of catchment internal sources. The highest concentrations were measured in the springs at the bottom of the rock glacier. Ground surface temperatures of the rock glacier indicated a high probability of permafrost occurrence, while the annual mean air temperature after the mid-1980s showed continuously positive deviations from the longterm average values (period 1961-1990) with increasing values after 2010. δ 34 S of sulfate in the inlets and the outflow indicated that sulfate in Lake Leit mainly derived from dissolution of gypsum/anhydrite even if its presence is not confirmed by the Geologic Atlas of Switzerland. Because of these results, we postulate the presence of subsurface traces of sulfate-bearing evaporites, probably associated with Triassic metasediments. These deposits are very common in the closer surroundings. We further hypothesize that the thawing of permafrost affects the flow path of water enabling its contact with fresh highly weatherable minerals increasing the overall weathering rate and shifting the relative ionic composition in the discharge toward the ions that originate from the most soluble minerals. This study shows that increased permafrost thawing in the future can influence water quality in highalpine settings.

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Section: Discussionmentioning

confidence: 99%

Climate Change-Induced Changes in the Chemistry of a High-Altitude Mountain Lake in the Central Alps

Steingruber

Bernasconi

Valenti³

2020

Aquat Geochem

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“…The presence of carbonate was not directly confirmed but was supported by elevated Ca/Na (up to 3.9 mol/mol) and Ca/Mg (up to 3.5 mol/mol) ratios in those water samples compared to a pure silicate end-member (Ca/Na = 0.5; Ca/Mg = 1.3, Wimpenny et al, 2011). Further, calcite has recently been detected in a glacier borehole sample from the AKR catchment (Figure 1, Harper et al, 2016) and the presence of disseminated calcite was inferred from element ratios of the fine fraction of till samples from north of Russell Glacier (Auqué et al, 2019). The estimated contribution of carbonate weathering to dissolved Mg was 2-7% (Wimpenny et al, 2011) and this estimate is consistent with other studies conducted in this region (Graly et al, 2014;Yde et al, 2014;Andrews and Jacobson, 2018).…”

Section: Mineral Source Control On River Water Isotope Ratiosmentioning

confidence: 90%

“…Therefore, an accurate assessment of their contribution to the dissolved Mg and Li load in Leverett must await further data. We note though that Andrews and Jacobson (2018) concluded, based on 87 Sr/ 86 Sr and major element data, that the waters draining Point 660 catchment [where Auqué et al (2019) collected their samples] drained a distinctly different lithology to Leverett, with a greater proportion of K-feldspar and/or biotite weathering compared to plagioclase weathering. Therefore, the contribution of biotite weathering to the dissolved load of Leverett River is expected to be lower compared to Russell.…”

Section: Mineral Source Control On River Water Isotope Ratiosmentioning

confidence: 92%

“…Adsorption of metal cations (e.g., Li) onto these phases could therefore occur, particularly as adsorption is favored at basic pH due to a more negative surface charge compared to at neutral pH (Stumm and Morgan, 1996). Although Wimpenny et al (2010) and Auqué et al (2019) considered the formation of secondary clay minerals unlikely, smectite has been detected in sediments retrieved from glacier boreholes in this region (Graly et al, 2016). Smectite may originate from overridden soils (Yde et al, 2014;Carrivick et al, 2018) and adsorption onto the clay surface could also induce isotope fractionation (Pistiner and Henderson, 2003;Chan and Hein, 2007).…”

Section: Fractionation Control On River Water Isotope Ratiosmentioning

confidence: 94%

“…Mg-and Li-rich minerals in the augen gneiss sample analyzed by Rickli et al (2017) are biotite and hornblende (both 3 wt.%). Biotite was inferred to contribute to the dissolved load chemistry of the Russell Glacier river (Andrews and Jacobson, 2018;Auqué et al, 2019) and is found in river sediments from the Leverett catchment (<1.4 wt.%, Rickli et al, 2017). Mineral separates of the augen gneiss were not obtained and given the spread of δ 7 Li and δ 26 Mg in minerals from different rock samples is quite large (Figure 4), it is difficult to predict what the δ 7 Li and δ 26 Mg values of the Mg-and Li-rich augen gneiss minerals would be.…”

Section: Mineral Source Control On River Water Isotope Ratiosmentioning

confidence: 99%

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Mg and Li Stable Isotope Ratios of Rocks, Minerals, and Water in an Outlet Glacier of the Greenland Ice Sheet

2019

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Magnesium and lithium stable isotope ratios (δ 26 Mg and δ 7 Li) have shown promise as tools to elucidate biogeochemical processes both at catchment scales and in deciphering global climate processes. Nevertheless, the controls on riverine Mg and Li isotope ratios are often difficult to determine as a myriad of factors can cause fractionation from bulk rock values such as secondary mineral formation and preferential weathering of isotopically distinct mineral phases. Quantifying the relative contribution from carbonate and silicate minerals to the dissolved load of glacierized catchments is particularly crucial for determining the role of chemical weathering in modulating the carbon cycle over glacial-interglacial periods. In this study we report Mg and Li isotope data for water, river sediment, rock, and mineral separates from the Leverett Glacier catchment, West Greenland. We assess whether the silicate mineral contributions to the dissolved load, previously determined using radiogenic Sr, Ca, Nd, and Hf isotopes, are consistent with dissolved Mg and Li isotope data, or whether a carbonate contribution is required as inferred previously for this region. For δ 7 Li, the average dissolved river water value (+19.2 ± 2.5 , 2SD) was higher than bedrock, river sediment, and mineral δ 7 Li values, implying a fractionation process. For δ 26 Mg, the average dissolved river water value (−0.30 ± 0.14 , 2SD) was within error of bedrock and river sediment and within the range of mineral δ 26 Mg values (−1.63 to +0.06). The river δ 26 Mg values are consistent with the mixing of Mg derived from the same mineral phases previously identified from radiogenic isotope measurements as controlling the dissolved load chemistry. Glacier fed rivers previously measured in this region had δ 26 Mg values ∼0.80 lower than those measured in the Leverett River which could be caused by a larger contribution from garnet (−1.63) dissolution compared to Leverett. This study highlights that dissolved Mg and Li isotope ratios in the Leverett River are affected by different processes (mixing and fractionation), and that since variations in silicate mineral δ 26 Mg values exist, preferential weathering of individual silicate minerals should be considered in addition to carbonate when interpreting dissolved δ 26 Mg values.

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The Influence of Petrographic Properties on Mechanical Characteristics and the Durability of the Greenschist Subjected to Simulated Weathering Tests

Zalooli,

Khamehchiyan,

Nikudel

et al. 2024

Rock Mech Rock Eng

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Chemical weathering in a moraine at the ice sheet margin at Kangerlussuaq, western Greenland

Cited by 12 publications

References 87 publications

Climate Change-Induced Changes in the Chemistry of a High-Altitude Mountain Lake in the Central Alps

Climate Change-Induced Changes in the Chemistry of a High-Altitude Mountain Lake in the Central Alps

Mg and Li Stable Isotope Ratios of Rocks, Minerals, and Water in an Outlet Glacier of the Greenland Ice Sheet

The Influence of Petrographic Properties on Mechanical Characteristics and the Durability of the Greenschist Subjected to Simulated Weathering Tests

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