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John C. Dixon - One of the best experts on this subject based on the ideXlab platform.
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Incipient weathering rind development on introduced machine-polished granite discs in an Arctic Alpine Environment, northern Scandinavia
Earth Surface Processes and Landforms, 2006Co-Authors: John C. Dixon, Sean W. Campbell, Colin E. Thorn, Robert G. DarmodyAbstract:Weathering rinds, zones of alteration on the exterior surfaces of rock outcrops and coarse unconsolidated surficial debris are widely used by geomorphologists and Quaternary geologists as indicators of the relative age of landforms and landscapes. Additionally they provide unique insights into the earliest stages of rock and mineral weathering, yet the origin of these alteration zones is relatively poorly understood. This lack of understanding applies especially to the initial stages of rind formation. The study reported in this paper has two principal objectives. The first is to use lightly polished granite discs inserted in soil profiles under several different plant communities in an Arctic Alpine Environment for a period of four or five years to investigate the nature of incipient weathering rind development. The second is to investigate the factors responsible for spatial variability in the nature and rates of rind formation. Incipient weathering rind development on the outer edges of the granite discs is observable and measurable over a period of time as short as four years in the mild Arctic Alpine Environment of Swedish Lapland. The earliest stages of rind development involve the development of a porous structure consisting of a combination of pits and fractures which have been solutionally enlarged and modified. Solution appears to be preferentially concentrated on the surfaces of feldspars and, to a lesser extent, quartz. In addition, iron oxides are present along grain boundaries and in grain interiors and are interpreted to have been derived from the oxidation of ferromagnesian minerals. Spatial variability in weathering rind development appears to be particularly driven by differences in moisture but is not related to soil pH. Copyright © 2005 John Wiley & Sons, Ltd.
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weathering rinds and rock coatings from an arctic Alpine Environment northern scandinavia
Geological Society of America Bulletin, 2002Co-Authors: John C. Dixon, Colin E. Thorn, R. G. Darmody, Sean W. CampbellAbstract:Coarse rock debris exposed in the subaerial Environment of northern Sweden displays the development of a wide variety of surface coatings. These include weathering rinds as well as a great diversity of geochemical coatings, including those dominated by Ca, Fe, Si, and Al. Each of these types of rock coatings displays a high degree of geochemical complexity. The weathering rinds exhibit both geochemical and morphologic changes to the parent rock cores, including extensive dissolution, oxidation, and hydration as well as disaggregation, fracturing, and cementation by secondary geochemical coatings. Chemical breakdown of the rock to form weathering rinds includes loss of K, Si, Mg, and Ca and buildup of Fe. Weathering rinds are fundamentally the result of dissolution, as no clay minerals were identified in the rinds. Rock coatings are distinguished from rinds by their clear accretionary nature. Despite the distinction made between weathering rinds and rock coatings, it is important to note that often the two are intimately related. The presence of rock coatings as well as weathering rinds on rock surfaces amplifies the important role played by geochemical processes in the Arctic Alpine climate of northern Sweden in particular, as well as its significance in landscape evolution in such Environments in general.
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weathering implications of water chemistry in an arctic Alpine Environment northern sweden
Geomorphology, 2000Co-Authors: R. G. Darmody, Colin E. Thorn, R.l. Harder, J.p.l. Schlyter, John C. DixonAbstract:This paper reports on some of the chemical characteristics of late melt-season water from Karkevagge (“valley of the boulders”) above the Arctic Circle in northern Sweden. Included in the analyses were temperature, electrical conductivity, pH, SO4, NO3, K, SiO2, Mg, Mn, Na, Fe, and Al. These were measured in rain, late-lying snow, and water from the major stream and lake, as well as from pond, tributary, and seep sources in the valley. A total of 71 samples was collected at 57 sites between August 6 and August 23, 1996 for the purpose of characterizing the present weathering regime within this classic U-shaped glacial valley. Evidence of chemical weathering included increases in solute concentrations over precipitation inputs and a source-related, wide variation in water chemistry. The dominant anion measured in surface water was SO4. That, along with the presence of CaSO4 coatings on streambeds, indicates that pyrite oxidation may contribute to the weathering regime. High SO4 concentrations were associated with gypsum-coated streambeds and seeps that emerge from the bedrock. Low SO4 concentrations were associated with tributaries flowing primarily on fresh rock and originating from melting snow. Estimated chemical denudation rate for the valley, corrected for atmospheric inputs, was 19.2 tons/km2/yr. Although this is lower than previously reported, our research supports earlier work indicating that chemical weathering is a major component of mass wasting in this arctic–Alpine Environment.
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Weathering implications of water chemistry in an arctic–Alpine Environment, northern Sweden
Geomorphology, 2000Co-Authors: R. G. Darmody, Colin E. Thorn, R.l. Harder, J.p.l. Schlyter, John C. DixonAbstract:This paper reports on some of the chemical characteristics of late melt-season water from Karkevagge (“valley of the boulders”) above the Arctic Circle in northern Sweden. Included in the analyses were temperature, electrical conductivity, pH, SO4, NO3, K, SiO2, Mg, Mn, Na, Fe, and Al. These were measured in rain, late-lying snow, and water from the major stream and lake, as well as from pond, tributary, and seep sources in the valley. A total of 71 samples was collected at 57 sites between August 6 and August 23, 1996 for the purpose of characterizing the present weathering regime within this classic U-shaped glacial valley. Evidence of chemical weathering included increases in solute concentrations over precipitation inputs and a source-related, wide variation in water chemistry. The dominant anion measured in surface water was SO4. That, along with the presence of CaSO4 coatings on streambeds, indicates that pyrite oxidation may contribute to the weathering regime. High SO4 concentrations were associated with gypsum-coated streambeds and seeps that emerge from the bedrock. Low SO4 concentrations were associated with tributaries flowing primarily on fresh rock and originating from melting snow. Estimated chemical denudation rate for the valley, corrected for atmospheric inputs, was 19.2 tons/km2/yr. Although this is lower than previously reported, our research supports earlier work indicating that chemical weathering is a major component of mass wasting in this arctic–Alpine Environment.
Olivier Dangles - One of the best experts on this subject based on the ideXlab platform.
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unexpected mechanisms sustain the stress gradient hypothesis in a tropical Alpine Environment
Journal of Vegetation Science, 2012Co-Authors: Fabien Anthelme, Belen Buendia, Charlotte Mazoyer, Olivier DanglesAbstract:AbstractQuestions: Does facilitation among plants increase with elevation in a humidtropical Alpine system in which climatic and ecological conditions differ fromotherAlpineEnvironments?Whatmechanismsareinvolvedintheinteractions?Location: Volcano Antisana, Eastern Cordillera of the Ecuadorian Andes(00 °28 ′S,78 09W).Methods: We selected the cushion-forming Azorella aretioides as a potentialnurse plant along an altitudinal gradient (4400, 4550 and 4700 m) in the hightropical Andes. We quantified its effects on other plants at species and commu-nity levels by comparing the product vegetation cover 9 number of individualsof every vascular species found inside and outside 265 cushions, using the rela-tive interaction index. We inferred potential mechanisms behind the interac-tions through analysis of microclimate, soil moisture and soil nutrientmeasurementsinsideandoutsidecushions.Results: Predictions of the stress gradient hypothesis (SGH) were corroboratedat community level, with transition from competitive or neutral effects of A.aretioides at 4400 and 4550 m to facilitative effects at 4700 m. Strong species-specific effects were observed along the altitudinal gradient, with a substantialeffect of local habitat disturbance on the outcome of plant–plant interactions.Surprisingly, cushions lowered air and soil temperatures and air humidity,whichreducedathigherelevations.Facilitationappearedtobecausedbyhighersoilmoistureandnutrientcontentbeneathcushions.Conclusions:OurdataextendtheframeworkoftheSGHbycorroboratingitforthe first time in a tropical Alpine system. However, the mechanisms underlyingplant–plantinteractionsdifferedfromthosegenerallyreportedfromAlpineenvi-ronments,withfacilitationvaryingaccordingtoresource-mediatedstress(nutri-ents).ItremainstobetestedwhetherthisisspecifictotropicalAlpinesystems.IntroductionSince the seminal paper of Bertness & Callaway (1994),the stressgradient hypothesis (SGH) has imposed itselfasamajorconceptinunderstandingtheeffectsofenvironmen-talstressonplantcommunitydistributioninawidevarietyofEnvironments(Callaway2007;Brookeret al.2008;Lor-tie 2010). As recently proposed by Maestre et al. (2009), itis crucial to determine the relative importance of resource(e.g. nutrients, light, water) vs. non-resource stress (e.g.temperature, wind, salinity) in order to achieve a betterunderstanding of the high variability in the outcome ofplant–plant interactions at the extremities of stress gradi-ents (Michalet 2007; Brooker et al. 2008; Maestre et al.2009; le Roux & McGeoch 2010). This issue has been par-ticularly addressed in Alpine Environments where plant–plantinteractionshavebeensuggestedtobemainlydrivenby non-resource stress (Maestre et al. 2009), therebyexplaining why facilitation processes are generally intenseattheendofstressgradientsintheseecosystems.Most(ifnotall)ofwhatweknowaboutSGHpredictionsinAlpinesystemshasbeenlearnedfrommountainsintem-perate and sub-polar latitudes. A world map view of loca-tions of the many SGH studies performed so far in AlpineEnvironments shows that tropical region virtually remainsa ‘SGH terra incognita’ (Fig. 1; but see Cavieres & Badano
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Unexpected mechanisms sustain the stress gradient hypothesis in a tropical Alpine Environment
Journal of Vegetation Science, 2012Co-Authors: Fabien Anthelme, Belen Buendia, Charlotte Mazoyer, Olivier DanglesAbstract:Questions : Does facilitation among plants increase with elevation in a humid tropical Alpine system in which climatic and ecological conditions differ from other Alpine Environments? What mechanisms are involved in the interactions? Location : Volcano Antisana, Eastern Cordillera of the Ecuadorian Andes (00°28′S, 78°09′W). Methods : We selected the cushion-forming Azorella aretioides as a potential nurse plant along an altitudinal gradient (4400, 4550 and 4700 m) in the high tropical Andes. We quantified its effects on other plants at species and community levels by comparing the product vegetation cover × number of individuals of every vascular species found inside and outside 265 cushions, using the relative interaction index. We inferred potential mechanisms behind the interactions through analysis of microclimate, soil moisture and soil nutrient measurements inside and outside cushions. Results : Predictions of the stress gradient hypothesis (SGH) were corroborated at community level, with transition from competitive or neutral effects of A. aretioides at 4400 and 4550 m to facilitative effects at 4700 m. Strong species-specific effects were observed along the altitudinal gradient, with a substantial effect of local habitat disturbance on the outcome of plant-plant interactions. Surprisingly, cushions lowered air and soil temperatures and air humidity, which reduced at higher elevations. Facilitation appeared to be caused by higher soil moisture and nutrient content beneath cushions. Conclusions : Our data extend the framework of the SGH by corroborating it for the first time in a tropical Alpine system. However, the mechanisms underlying plant-plant interactions differed from those generally reported from Alpine Environments, with facilitation varying according to resource-mediated stress (nutrients). It remains to be tested whether this is specific to tropical Alpine systems.
Katharina Hufner - One of the best experts on this subject based on the ideXlab platform.
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viewing an Alpine Environment positively affects emotional analytics in patients with somatoform depressive and anxiety disorders as well as in healthy controls
BMC Psychiatry, 2020Co-Authors: Katharina Hufner, Cornelia Ower, Georg Kemmler, Theresa Vill, Caroline Martini, Andrea Schmitt, Barbara SpernerunterwegerAbstract:Patients with somatoform, depressive or anxiety disorders often don’t respond well to medical treatment and experience many side effects. It is thus of clinical relevance to identify alternative, scientifically based, treatments. Our approach is based on the recent evidence that urbanicity has been shown to be associated with an increased risk for mental disorders. Conversely, green and blue Environments show a dose-dependent beneficial impact on mental health. Here we evaluate the effect of viewing stimuli of individuals in an Alpine Environment on emotional analytics in 183 patients with psychiatric disorders (mostly somatoform, depressive and anxiety disorders) and 315 healthy controls (HC). Emotional analytics (valence: unhappy vs happy, arousal: calm vs excited, dominance: controlled vs in control) were assessed using the Self-Assessment Manikin. Further parameters related to mental health and physical activity were recorded. Emotional analytics of patients indicated that they felt less happy, less in control and had higher levels of arousal than HC when viewing neutral stimuli. The comparison Alpine>neutral stimuli showed a significant positive effect of Alpine stimuli on emotional analytics in both groups. Patients and HC both felt attracted to the scenes displayed in the Alpine stimuli. Emotional analytics correlated positively with resilience and inversely with perceived stress. Preventive and therapeutic programs for patients with somatoform, depressive and anxiety disorders should consider taking the benefits of natural outdoor Environments, such as Alpine Environments, into account. Organizational barriers which are preventing the implementation of such programs in clinical practice need to be identified and addressed.
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Viewing an Alpine Environment positively affects emotional analytics in patients with somatoform, depressive and anxiety disorders as well as in healthy controls
2020Co-Authors: Katharina Hufner, Cornelia Ower, Georg Kemmler, Theresa Vill, Caroline Martini, Andrea Schmitt, Barbara Sperner-unterwegerAbstract:Abstract Background: Patients with somatoform, depressive or anxiety disorders often don´t respond well to medical treatment and experience many side effects. It is thus of clinical relevance to identify alternative, scientifically based, treatments. Our approach is based on the recent evidence that urbanicity has been shown to be associated with an increased risk for mental disorders. Conversely, green and blue Environments show a dose-dependent beneficial impact on mental health. Methods: Here we evaluate the effect of viewing stimuli of individuals in an Alpine Environment on emotional analytics in 183 patients with psychiatric disorders (mostly somatoform, depressive and anxiety disorders) and 315 healthy controls (HC). Emotional analytics (valence: unhappy vs happy, arousal: calm vs excited, dominance: controlled vs in control) were assessed using the Self-Assessment Manikin. Further parameters related to mental health and physical activity were recorded.Results: Emotional analytics of patients indicated that they feel less happy, less in control and had higher levels of arousal than HC when viewing neutral stimuli. The comparison Alpine>neutral stimuli showed a significant a positive effect of Alpine stimuli on emotional analytics in both groups. Patients and HC both felt attracted to the scenes displayed in the Alpine stimuli. Emotional analytics correlated positively with resilience and inversely with perceived stress.Conclusions: Preventive and therapeutic programs for patients with somatoform, depressive and anxiety disorders should consider taking the benefits of natural outdoor Environments such as Alpine Environments, into account. Organizational barriers which are preventing the implementation of such programs in clinical practice need to be identified and addressed.
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Viewing an Alpine Environment positively affects emotional analytics in patients with somatoform, depressive and anxiety disorders as well as in healthy controls
2020Co-Authors: Katharina Hufner, Cornelia Ower, Georg Kemmler, Theresa Vill, Caroline Martini, Andrea Schmitt, Barbara Sperner-unterwegerAbstract:Abstract Background: Patients with somatoform, depressive or anxiety disorders often don´t respond well to medical treatment and experience many side effects. It is thus of clinical relevance to identify alternative, scientifically based, treatments. Our approach is based on the recent evidence that urbanicity has been shown to be associated with an increased risk for mental disorders. Conversely green and blue Environments show a dose-dependent beneficial impact on mental health. Methods: Here we evaluate the effect of viewing stimuli of individuals in an Alpine Environment on emotional analytics in 183 patients with psychiatric disorders (mostly somatoform, depressive and anxiety disorders) and 315 healthy controls (HC). Emotional analytics (valence: unhappy vs happy, arousal: calm vs excited, dominance: controlled vs in control) were assessed using the Self-Assessment Manikin. Further parameters related to mental health and physical activity were recorded.Results: Emotional analytics of patients indicated that they feel less happy, less in control and had higher levels of arousal than HC when viewing neutral stimuli. The comparison Alpine>neutral stimuli showed a significant a positive effect of Alpine stimuli on emotional analytics in both groups. Patients and HC both felt attracted to the scenes displayed in the Alpine stimuli. Emotional analytics correlated positively with resilience and inversely with perceived stress.Conclusions: Preventive and therapeutic programs for patients with somatoform, depressive and anxiety disorders should consider taking the benefits of natural outdoor such as Alpine Environments, into account. Organizational barriers which are preventing the implementation of such programs in clinical practice need to be identified and addressed.
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Viewing an Alpine Environment positively affects emotional analytics in patients with stress-related psychiatric disorders and healthy controls
2020Co-Authors: Katharina Hufner, Cornelia Ower, Georg Kemmler, Theresa Vill, Caroline Martini, Andrea Schmitt, Barbara Sperner-unterwegerAbstract:Abstract Background: Patients with stress-related psychiatric (psychosomatic) disorders often don´t respond well to medical treatment and experience many side effects. It is thus of clinical relevance to identify alternative, scientifically based, treatments. Our approach is based on the recent evidence that urbanicity has been shown to be associated with an increased risk for mental disorders. Conversely green and blue Environments show a dose-dependent beneficial impact on mental health. Methods: Here we evaluate the effect of viewing stimuli of individuals in an Alpine Environment on emotional analytics in 183 patients with stress-related psychiatric disorders and 315 healthy controls (HC). Emotional analytics (valence: unhappy vs happy, arousal: calm vs excited, dominance: controlled vs in control) were assessed using the Self-Assessment Manikin. Further parameters related to mental health and physical activity were recorded. Results: Emotional analytics of patients indicated that they feel less happy, less in control and had higher levels of arousal than HC when viewing neutral stimuli. The comparison Alpine>neutral stimuli showed a significant a positive effect of Alpine stimuli on emotional analytics in both groups. Patients and HC both felt attracted to the scenes displayed in the Alpine stimuli. Emotional analytics correlated positively with resilience and inversely with perceived stress. Conclusions: Preventive and therapeutic programs for patients with stress-related psychiatric disorders should consider taking the benefits of outdoor natural Environments into account. Organizational barriers which are preventing the implementation of such programs in clinical practice need to be identified and addressed.
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Viewing an Alpine Environment positively affects emotional analytics in patients with stress-related psychiatric disorders
2020Co-Authors: Katharina Hufner, Cornelia Ower, Georg Kemmler, Theresa Vill, Caroline Martini, Andrea Schmitt, Barbara Sperner-unterwegerAbstract:Abstract Background: Patients with stress-related psychiatric (psychosomatic) disorders often don´t respond well to medical treatment and experience many side effects. It is thus of clinical relevance to identify alternative, scientifically based, treatments. Our approach is based on the recent evidence that urbanicity has been shown to be associated with an increased risk for mental disorders. Conversely green and blue Environments show a dose-dependent beneficial impact on mental health. Methods: Here we evaluate the effect of viewing stimuli of individuals in an Alpine Environment on emotional analytics in 183 patients with stress-related psychiatric disorders and 315 healthy controls (HC). Emotional analytics (valence: unhappy vs happy, arousal: calm vs excited, dominance: controlled vs in control) were assessed using the Self-Assessment Manikin. Results: Patients showed significantly lower levels of resilience and significantly higher scores of self-perceived stress. Emotional analytics of patients indicated that they feel less happy, less in control and had higher levels of arousal than HC when viewing neutral stimuli. The comparison Alpine>neutral stimuli showed a significant a positive effect of Alpine stimuli on emotional analytics in both groups. Patients and HC both felt attracted to the scenes displayed in the Alpine stimuli. Emotional analytics correlated positively with resilience and inversely with perceived stress. Conclusions: Preventive and therapeutic programs for patients with stress-related psychiatric disorders should take benefits of outdoor natural Environments into account. Organizational barriers which are preventing the implementation of such programs in clinical practice need to be identified and addressed.
Colin E. Thorn - One of the best experts on this subject based on the ideXlab platform.
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Incipient weathering rind development on introduced machine-polished granite discs in an Arctic Alpine Environment, northern Scandinavia
Earth Surface Processes and Landforms, 2006Co-Authors: John C. Dixon, Sean W. Campbell, Colin E. Thorn, Robert G. DarmodyAbstract:Weathering rinds, zones of alteration on the exterior surfaces of rock outcrops and coarse unconsolidated surficial debris are widely used by geomorphologists and Quaternary geologists as indicators of the relative age of landforms and landscapes. Additionally they provide unique insights into the earliest stages of rock and mineral weathering, yet the origin of these alteration zones is relatively poorly understood. This lack of understanding applies especially to the initial stages of rind formation. The study reported in this paper has two principal objectives. The first is to use lightly polished granite discs inserted in soil profiles under several different plant communities in an Arctic Alpine Environment for a period of four or five years to investigate the nature of incipient weathering rind development. The second is to investigate the factors responsible for spatial variability in the nature and rates of rind formation. Incipient weathering rind development on the outer edges of the granite discs is observable and measurable over a period of time as short as four years in the mild Arctic Alpine Environment of Swedish Lapland. The earliest stages of rind development involve the development of a porous structure consisting of a combination of pits and fractures which have been solutionally enlarged and modified. Solution appears to be preferentially concentrated on the surfaces of feldspars and, to a lesser extent, quartz. In addition, iron oxides are present along grain boundaries and in grain interiors and are interpreted to have been derived from the oxidation of ferromagnesian minerals. Spatial variability in weathering rind development appears to be particularly driven by differences in moisture but is not related to soil pH. Copyright © 2005 John Wiley & Sons, Ltd.
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weathering rinds and rock coatings from an arctic Alpine Environment northern scandinavia
Geological Society of America Bulletin, 2002Co-Authors: John C. Dixon, Colin E. Thorn, R. G. Darmody, Sean W. CampbellAbstract:Coarse rock debris exposed in the subaerial Environment of northern Sweden displays the development of a wide variety of surface coatings. These include weathering rinds as well as a great diversity of geochemical coatings, including those dominated by Ca, Fe, Si, and Al. Each of these types of rock coatings displays a high degree of geochemical complexity. The weathering rinds exhibit both geochemical and morphologic changes to the parent rock cores, including extensive dissolution, oxidation, and hydration as well as disaggregation, fracturing, and cementation by secondary geochemical coatings. Chemical breakdown of the rock to form weathering rinds includes loss of K, Si, Mg, and Ca and buildup of Fe. Weathering rinds are fundamentally the result of dissolution, as no clay minerals were identified in the rinds. Rock coatings are distinguished from rinds by their clear accretionary nature. Despite the distinction made between weathering rinds and rock coatings, it is important to note that often the two are intimately related. The presence of rock coatings as well as weathering rinds on rock surfaces amplifies the important role played by geochemical processes in the Arctic Alpine climate of northern Sweden in particular, as well as its significance in landscape evolution in such Environments in general.
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weathering implications of water chemistry in an arctic Alpine Environment northern sweden
Geomorphology, 2000Co-Authors: R. G. Darmody, Colin E. Thorn, R.l. Harder, J.p.l. Schlyter, John C. DixonAbstract:This paper reports on some of the chemical characteristics of late melt-season water from Karkevagge (“valley of the boulders”) above the Arctic Circle in northern Sweden. Included in the analyses were temperature, electrical conductivity, pH, SO4, NO3, K, SiO2, Mg, Mn, Na, Fe, and Al. These were measured in rain, late-lying snow, and water from the major stream and lake, as well as from pond, tributary, and seep sources in the valley. A total of 71 samples was collected at 57 sites between August 6 and August 23, 1996 for the purpose of characterizing the present weathering regime within this classic U-shaped glacial valley. Evidence of chemical weathering included increases in solute concentrations over precipitation inputs and a source-related, wide variation in water chemistry. The dominant anion measured in surface water was SO4. That, along with the presence of CaSO4 coatings on streambeds, indicates that pyrite oxidation may contribute to the weathering regime. High SO4 concentrations were associated with gypsum-coated streambeds and seeps that emerge from the bedrock. Low SO4 concentrations were associated with tributaries flowing primarily on fresh rock and originating from melting snow. Estimated chemical denudation rate for the valley, corrected for atmospheric inputs, was 19.2 tons/km2/yr. Although this is lower than previously reported, our research supports earlier work indicating that chemical weathering is a major component of mass wasting in this arctic–Alpine Environment.
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Weathering implications of water chemistry in an arctic–Alpine Environment, northern Sweden
Geomorphology, 2000Co-Authors: R. G. Darmody, Colin E. Thorn, R.l. Harder, J.p.l. Schlyter, John C. DixonAbstract:This paper reports on some of the chemical characteristics of late melt-season water from Karkevagge (“valley of the boulders”) above the Arctic Circle in northern Sweden. Included in the analyses were temperature, electrical conductivity, pH, SO4, NO3, K, SiO2, Mg, Mn, Na, Fe, and Al. These were measured in rain, late-lying snow, and water from the major stream and lake, as well as from pond, tributary, and seep sources in the valley. A total of 71 samples was collected at 57 sites between August 6 and August 23, 1996 for the purpose of characterizing the present weathering regime within this classic U-shaped glacial valley. Evidence of chemical weathering included increases in solute concentrations over precipitation inputs and a source-related, wide variation in water chemistry. The dominant anion measured in surface water was SO4. That, along with the presence of CaSO4 coatings on streambeds, indicates that pyrite oxidation may contribute to the weathering regime. High SO4 concentrations were associated with gypsum-coated streambeds and seeps that emerge from the bedrock. Low SO4 concentrations were associated with tributaries flowing primarily on fresh rock and originating from melting snow. Estimated chemical denudation rate for the valley, corrected for atmospheric inputs, was 19.2 tons/km2/yr. Although this is lower than previously reported, our research supports earlier work indicating that chemical weathering is a major component of mass wasting in this arctic–Alpine Environment.
R. G. Darmody - One of the best experts on this subject based on the ideXlab platform.
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weathering rinds and rock coatings from an arctic Alpine Environment northern scandinavia
Geological Society of America Bulletin, 2002Co-Authors: John C. Dixon, Colin E. Thorn, R. G. Darmody, Sean W. CampbellAbstract:Coarse rock debris exposed in the subaerial Environment of northern Sweden displays the development of a wide variety of surface coatings. These include weathering rinds as well as a great diversity of geochemical coatings, including those dominated by Ca, Fe, Si, and Al. Each of these types of rock coatings displays a high degree of geochemical complexity. The weathering rinds exhibit both geochemical and morphologic changes to the parent rock cores, including extensive dissolution, oxidation, and hydration as well as disaggregation, fracturing, and cementation by secondary geochemical coatings. Chemical breakdown of the rock to form weathering rinds includes loss of K, Si, Mg, and Ca and buildup of Fe. Weathering rinds are fundamentally the result of dissolution, as no clay minerals were identified in the rinds. Rock coatings are distinguished from rinds by their clear accretionary nature. Despite the distinction made between weathering rinds and rock coatings, it is important to note that often the two are intimately related. The presence of rock coatings as well as weathering rinds on rock surfaces amplifies the important role played by geochemical processes in the Arctic Alpine climate of northern Sweden in particular, as well as its significance in landscape evolution in such Environments in general.
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weathering implications of water chemistry in an arctic Alpine Environment northern sweden
Geomorphology, 2000Co-Authors: R. G. Darmody, Colin E. Thorn, R.l. Harder, J.p.l. Schlyter, John C. DixonAbstract:This paper reports on some of the chemical characteristics of late melt-season water from Karkevagge (“valley of the boulders”) above the Arctic Circle in northern Sweden. Included in the analyses were temperature, electrical conductivity, pH, SO4, NO3, K, SiO2, Mg, Mn, Na, Fe, and Al. These were measured in rain, late-lying snow, and water from the major stream and lake, as well as from pond, tributary, and seep sources in the valley. A total of 71 samples was collected at 57 sites between August 6 and August 23, 1996 for the purpose of characterizing the present weathering regime within this classic U-shaped glacial valley. Evidence of chemical weathering included increases in solute concentrations over precipitation inputs and a source-related, wide variation in water chemistry. The dominant anion measured in surface water was SO4. That, along with the presence of CaSO4 coatings on streambeds, indicates that pyrite oxidation may contribute to the weathering regime. High SO4 concentrations were associated with gypsum-coated streambeds and seeps that emerge from the bedrock. Low SO4 concentrations were associated with tributaries flowing primarily on fresh rock and originating from melting snow. Estimated chemical denudation rate for the valley, corrected for atmospheric inputs, was 19.2 tons/km2/yr. Although this is lower than previously reported, our research supports earlier work indicating that chemical weathering is a major component of mass wasting in this arctic–Alpine Environment.
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Weathering implications of water chemistry in an arctic–Alpine Environment, northern Sweden
Geomorphology, 2000Co-Authors: R. G. Darmody, Colin E. Thorn, R.l. Harder, J.p.l. Schlyter, John C. DixonAbstract:This paper reports on some of the chemical characteristics of late melt-season water from Karkevagge (“valley of the boulders”) above the Arctic Circle in northern Sweden. Included in the analyses were temperature, electrical conductivity, pH, SO4, NO3, K, SiO2, Mg, Mn, Na, Fe, and Al. These were measured in rain, late-lying snow, and water from the major stream and lake, as well as from pond, tributary, and seep sources in the valley. A total of 71 samples was collected at 57 sites between August 6 and August 23, 1996 for the purpose of characterizing the present weathering regime within this classic U-shaped glacial valley. Evidence of chemical weathering included increases in solute concentrations over precipitation inputs and a source-related, wide variation in water chemistry. The dominant anion measured in surface water was SO4. That, along with the presence of CaSO4 coatings on streambeds, indicates that pyrite oxidation may contribute to the weathering regime. High SO4 concentrations were associated with gypsum-coated streambeds and seeps that emerge from the bedrock. Low SO4 concentrations were associated with tributaries flowing primarily on fresh rock and originating from melting snow. Estimated chemical denudation rate for the valley, corrected for atmospheric inputs, was 19.2 tons/km2/yr. Although this is lower than previously reported, our research supports earlier work indicating that chemical weathering is a major component of mass wasting in this arctic–Alpine Environment.