Silicate weathering of soil-mantled slopes in an active Alpine landscape

Norton, Kevin; Blanckenburg, Friedhelm von

doi:10.1016/j.gca.2010.06.019

Cited by 54 publications

(40 citation statements)

References 63 publications

(137 reference statements)

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“…3 A and B). Topography and erosion rates can regulate sediment size by influencing sediment residence times, with slower erosion on gentler slopes leading to longer exposure to weathering (3,35) and thus finer sediment supplied to channels. This hypothesis is consistent with the observed slower erosion and enhanced delivery of the finer sediment from lower, more gently sloped elevations at Inyo Creek (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…weathering | erosion | critical zone | detrital thermochronometry T he interplay of climate and life drives weathering on mountain slopes (1)(2)(3)(4), converting intact bedrock into mobile sediment particles ranging in size from clay to boulders (5,6). Water, wind, and biota sweep these particles across slopes under the force of gravity and erode them into channels, where they serve as tools that cut into underlying bedrock during transport downstream (7).…”

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confidence: 99%

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Climate and topography control the size and flux of sediment produced on steep mountain slopes

Riebe

Sklar

Lukens

et al. 2015

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

105

141

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Weathering on mountain slopes converts rock to sediment that erodes into channels and thus provides streams with tools for incision into bedrock. Both the size and flux of sediment from slopes can influence channel incision, making sediment production and erosion central to the interplay of climate and tectonics in landscape evolution. Although erosion rates are commonly measured using cosmogenic nuclides, there has been no complementary way to quantify how sediment size varies across slopes where the sediment is produced. Here we show how this limitation can be overcome using a combination of apatite helium ages and cosmogenic nuclides measured in multiple sizes of stream sediment. We applied the approach to a catchment underlain by granodiorite bedrock on the eastern flanks of the High Sierra, in California. Our results show that higher-elevation slopes, which are steeper, colder, and less vegetated, are producing coarser sediment that erodes faster into the channel network. This suggests that both the size and flux of sediment from slopes to channels are governed by altitudinal variations in climate, vegetation, and topography across the catchment. By quantifying spatial variations in the sizes of sediment produced by weathering, this analysis enables new understanding of sediment supply in feedbacks between climate, tectonics, and mountain landscape evolution.weathering | erosion | critical zone | detrital thermochronometry T he interplay of climate and life drives weathering on mountain slopes (1-4), converting intact bedrock into mobile sediment particles ranging in size from clay to boulders (5, 6). Water, wind, and biota sweep these particles across slopes under the force of gravity and erode them into channels, where they serve as tools that cut into underlying bedrock during transport downstream (7). Both the size and flux of particles eroded from slopes into channels can influence incision into bedrock (8, 9), which in turn governs the pace of erosion from slopes where the sediment is produced (10, 11). The relationships between sediment production, hillslope erosion, and channel incision imply that they are central to feedbacks that drive mountain landscape evolution (12). When channel incision and hillslope erosion are relatively fast, sediment particles spend less time exposed to weathering on slopes (13) and thus may be coarser when they enter the channel (14), promoting faster incision into bedrock (7). Integrated over time, channel incision and hillslope erosion generate topography (15), imposing altitudinal gradients in precipitation, temperature, and hillslope form (16), and thus ultimately influencing erosion (17), weathering (1), and the sizes of sediment produced on slopes (2). Thus, the size and erosional flux of sediment may both depend on and regulate rates of channel incision into bedrock via feedbacks spanning a range of scales and processes.Feedbacks between climate, erosion, and tectonics have been widely studied (8,16,(18)(19)(20)(21)(22)(23). However, understanding the role of sedi...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Climate and topography control the size and flux of sediment produced on steep mountain slopes

Riebe

Sklar

Lukens

et al. 2015

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

105

141

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“…Soil production rates (20-220 t/km 2 /y) were similar to rates estimated for alpine regions elsewhere (32-346 t/km 2 /y) (Egli et al, 2014;Norton and von Blanckenburg, 2010) and were towards the upper end of rates reported for non-alpine soils within Australia (16-118 t/km 2 /y) (Stockmann et al, 2014;Suresh et al, 2013). Thus, this study adds to the global data set demonstrating rapid soil production rates in alpine areas where moisture availability and vegetation productivity is high (Riebe et al, 2004 Pb ex inventories imply that anthropogenic metals (Ag, Mo, Cd, Sb) are currently mobilised from hillslopes at a rates of <20 g/km 2 /y (Table 5.6).…”

Section: Objectivesupporting

confidence: 75%

“…However, in alpine regions experiencing rapid uplift and high precipitation, for example in the Southern Alps New Zealand, where rainfall may exceed 10 m/y and uplift approximates 10 mm/y, soil production rates may reach 2.5 mm/y, an order of magnitude higher than measured elsewhere . The significance of chemical weathering in mountain environments is further evidenced by the existence of extensive soil mantles in a variety of alpine settings worldwide (Dixon and Thorn, 2005;Egli et al, 2014;Norton and von Blanckenburg, 2010;Riebe et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

The fate of atmospheric metal pollutants in the landscape, Snowy Mountains, south-eastern Australia

Stromsoe¹

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Industrial metals, emitted to the atmosphere by human activity, have been transported and deposited to almost every location on Earth, including Antarctica and Greenland. This is demonstrated by an increasing body of literature in which many atmospheric industrial metals (e.g. Pb, Hg, Cd and Cu) have been shown to be significantly enriched in environmental archives. Studies have largely focussed on peat mires and ice cores, which receive high rates of atmospheric deposition relative to terrestrial inputs. By contrast, few studies have examined the extent of atmospherically derived metals across the wider landscape, where processes such as pedogenesis, erosion and sedimentation affect the spatial extent and magnitude of metal enrichment. In the Snowy Mountains, Australia, atmospheric pollutant metals have previously been identified in alpine peat mires, although their impact on the wider environment has not been assessed. Interest in the fate of atmospheric pollutants in the Snowy Mountains has increased due to the operation of a cloud seeding program in which, silver iodide, AgI, is released to the atmosphere, leading to concerns that silver, Ag, contamination may be accumulating in this ecologically important region. This thesis examines the spatial extent and magnitude of atmospherically derived metals in the SnowyMountains by investigating patterns of enrichment in a range of geomorphic settings and catchment positions, including in soils, peat mires, lakes and reservoirs. The potential movement of metals through the landscape was also assessed by examining rates of geomorphic processes, including rates of pedogenesis and erosion, determined via radionuclides. The thesis was undertaken in three parts which are summarised below. by atmospheric deposition (ombrotrophic peat mires in the upper parts of catchments), the order and magnitude of metal enrichment most closely resembled that of collected aerosols, however, on average enrichment was 5-7 fold lower than in the aerosols. Metals most sensitive to enrichment, i.e., those with low natural abundance in local sediments (Cd, Ag, Sb, Mo), were enriched in all environments including the most geomorphically active settings (tarn lake sediments). In reservoirs, located lower in catchments, patterns of metal enrichment largely reflected concentrations in catchment soils but metals were additionally enriched or depleted depending on their relative particle reactivity. For those metals which are most sensitive to enrichment (Ag, Cd, Sb), the increase in excess flux required to reach trigger value concentrations is lowest in the reservoir sediments (Ag: 13-18, Cd: 7-10 and Sb: 17-61 times the current flux) and highest in the tarn lake (Ag: 60, Cd: 15, Sb: 27 times the current flux) and the peat mire (Ag: 74, Cd: 15, Sb: 18 times the current flux).In part three of this thesis, rates of soil production and soil erosion were quantified using radiocarbon dating, fallout radionuclides and sediment yields in lakes and reservoirs in order to assess the stability of l...

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“…For example, in the Southern Alps New Zealand, where rainfall may exceed 10 m/y and uplift approximates 10 mm/y, soil production rates may reach 2.5 mm/y , an order of magnitude higher than soil production rates measured elsewhere . The potential significance of chemical weathering in mountain environments is further evidenced by the existence of extensive soil mantles in a variety of alpine settings worldwide (Dixon and Thorn, 2005;Egli et al, 2014;Norton and von Blanckenburg, 2010;Riebe et al, 2004). Soils in high mountain environments have been shown to be sensitive to changes in climate and human activity, which alter soil production processes and may accelerate the erosion rates by multiple orders of magnitude (Barsch and Caine, 1984).…”

Section: Introductionmentioning

confidence: 99%

Estimates of late Holocene soil production and erosion in the Snowy Mountains, Australia

Stromsoe

Marx

Callow

et al. 2016

CATENA

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Soil production in actively uplifting or high precipitation alpine landscapes is potentially rapid. However, these same landscapes are also susceptible to erosion and can be sensitive to changes in climate and anthropogenic activity which can upset the balance between soil production and erosion. The Snowy Mountains, southeastern Australia, are a tectonically stable, low relief, moderate precipitation mountain environment. The alpine area is extensively blanketed by soil that has been subjected to more intensive episodes of erosion during past periods of anthropogenic disturbance and under cold climate conditions of the late Quaternary. In this study, rates of soil development and hillslope erosion were investigated using radiocarbon dating, fallout radionuclides and sediment cores collected from lakes and reservoirs. Estimated Holocene soil development rates were 20-220 t/km2/y. Erosion rates determined from the radionuclides 137Cs and 210Pb were equivocal, due to the inherent spatial variability of radionuclide inventories relative to apparent erosion rates. Estimated average erosion rates over the past 100 years, determined from 210Pbex inventories, were 60 t/km2/y (95% CI: 10, 90). Inventories of 137Cs observed at the same site implied that more recent erosion rates (over the past 60 years) was below the detection limits of the sampling method applied here (i.e. /km2/y). The upper estimate of 90 t/km2/y is comparable to the mean erosion rate estimated using the radionuclide method for uncultivated sites in Australia and is significantly lower than that measured at sites were vegetation cover was disturbed by livestock grazing prior to its exclusion from the alpine area in the 1940s CE. Low erosion and high soil production rates relative to the lowland soils are likely related to extensive vegetation cover, which, in this context, protects soils against erosion and contributes to the formation of organic alpine soils, that rapidly accumulate organic matter by comparison to other soil types. Disciplines Medicine and Health Sciences | Social and Behavioral Sciences Publication DetailsStromsoe, N., Marx, S. K., Callow, N., McGowan, H. A. & Heijnis, H. (2016 AbstractSoil production in actively uplifting or high precipitation alpine landscapes is potentially rapid.However, these same landscapes are also susceptible to erosion and can be sensitive to changes in climate and anthropogenic activity which can upset the balance between soil production and erosion. The Snowy Mountains, southeastern Australia, are a tectonically stable, low relief, moderate precipitation mountain environment. The alpine area is extensively blanketed by soil that has been subjected to more intensive episodes of erosion during past periods of anthropogenic disturbance and under cold climate conditions of the late Quaternary. In this study, rates of soil development and hillslope erosion were investigated using radiocarbon dating, fallout radionuclides and sediment cores collected from lakes and reservoirs. the mean erosion rate est...

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Silicate weathering of soil-mantled slopes in an active Alpine landscape

Cited by 54 publications

References 63 publications

Climate and topography control the size and flux of sediment produced on steep mountain slopes

Climate and topography control the size and flux of sediment produced on steep mountain slopes

The fate of atmospheric metal pollutants in the landscape, Snowy Mountains, south-eastern Australia

Estimates of late Holocene soil production and erosion in the Snowy Mountains, Australia

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