Liyun Tang, Zihan Lu, Juanjuan Zheng, Jianguo Zheng, Long Jin, Yongtang Yu, H. Jia, Q. Sun, Di Wu, Gang Li
The mesoscale effect of climate change and engineering activities on a superficial frozen soil–rock mixture (FSRM) in regions is complex. The decrease in strength caused by particle ice film ablation under temperature rise has various effects, such as upper subgrade settlement deformation. However, the internal mechanism of FSRM strength degradation remains unclear. Triaxial and nuclear magnetic resonance tests on FSRM were performed at various temperatures to clarify the mechanism of FSRM internal degradation. The results show that the strength, cohesion, and internal friction angle of FSRM decrease with increasing temperature, and the attenuation is significant in the range of −5 to 0°C. The change in ice–water content can be divided into three stages (i.e., freezing, phase transformation, and complete melting). In the three stages, the maximum free water is only 24%, while the maximum bound water is 100% above 0°C. Based on the microscopic test results, a mesoscopic calculation model for FSRM particles was developed. It was found that the work between particles is consistent with the law of strength degradation, and the friction function by particles gradually changes to bite work with increasing temperature. By introducing the strain energy theory, the strain energy generated by particle shear work is considered the key index to reflect FSRM strength. The particle ice film locking effect is weakened under temperature rise, and the increase in water weakens the strain energy generated by the work of the bite friction between particles during the shear process. At the macro level, the strength of FSRM deteriorates.
{"title":"Mechanism of strength degradation of frozen soil–rock mixture under temperature rise‐induced particle ice film ablation","authors":"Liyun Tang, Zihan Lu, Juanjuan Zheng, Jianguo Zheng, Long Jin, Yongtang Yu, H. Jia, Q. Sun, Di Wu, Gang Li","doi":"10.1002/ppp.2202","DOIUrl":"https://doi.org/10.1002/ppp.2202","url":null,"abstract":"The mesoscale effect of climate change and engineering activities on a superficial frozen soil–rock mixture (FSRM) in regions is complex. The decrease in strength caused by particle ice film ablation under temperature rise has various effects, such as upper subgrade settlement deformation. However, the internal mechanism of FSRM strength degradation remains unclear. Triaxial and nuclear magnetic resonance tests on FSRM were performed at various temperatures to clarify the mechanism of FSRM internal degradation. The results show that the strength, cohesion, and internal friction angle of FSRM decrease with increasing temperature, and the attenuation is significant in the range of −5 to 0°C. The change in ice–water content can be divided into three stages (i.e., freezing, phase transformation, and complete melting). In the three stages, the maximum free water is only 24%, while the maximum bound water is 100% above 0°C. Based on the microscopic test results, a mesoscopic calculation model for FSRM particles was developed. It was found that the work between particles is consistent with the law of strength degradation, and the friction function by particles gradually changes to bite work with increasing temperature. By introducing the strain energy theory, the strain energy generated by particle shear work is considered the key index to reflect FSRM strength. The particle ice film locking effect is weakened under temperature rise, and the increase in water weakens the strain energy generated by the work of the bite friction between particles during the shear process. At the macro level, the strength of FSRM deteriorates.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":" ","pages":""},"PeriodicalIF":5.0,"publicationDate":"2023-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46960690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Erin C. Rooney, V. Bailey, Kaizad F. Patel, A. Kholodov, H. Golightly, R. Lybrand
Topography and canopy cover influence ground temperature in warming permafrost landscapes, yet soil temperature heterogeneity introduced by mesotopographic slope positions, microtopographic differences in vegetation cover, and the subsequent impact of contrasting temperature conditions on soil organic carbon (SOC) dynamics are understudied. Buffering of permafrost‐affected soils against warming air temperatures in boreal forests can reflect surface soil characteristics (e.g., thickness of organic material) as well as the degree and type of canopy cover (e.g., open cover vs. closed cover). Both landscape and soil properties interact to determine meso‐ and microscale heterogeneity of ground warming. We sampled a hillslope catena transect in a discontinuous permafrost zone near Fairbanks, Alaska, to test the small‐scale (1 to 3 m) impacts of slope position and cover type on soil organic matter composition. Mineral active layer samples were collected from backslope, low backslope, and footslope positions at depths spanning 19 to 60 cm. We examined soil mineralogical composition, soil moisture, total carbon and nitrogen content, and organic mat thickness in conjunction with an assessment of SOC composition using Fourier‐transform ion cyclotron resonance mass spectrometry (FT‐ICR‐MS). Soils in the footslope position had a higher relative contribution of lignin‐like compounds, whereas backslope soils had more aliphatic and condensed aromatic compounds as determined using FT‐ICR‐MS. The effect of open versus closed tree canopy cover varied with the slope position. On the backslope, we found higher oxidation of molecules under open cover than closed cover, indicating an effect of warmer soil temperature on decomposition. Little to no effect of the canopy was observed in soils at the footslope position, which we attributed, in part, to the strong impact of soil moisture content in SOC dynamics in the water‐gathering footslope position. The thin organic mat under open cover on the backslope position may have contributed to differences in soil temperature and thus SOC oxidation under open and closed canopies. Here, the thinner organic mat did not appear to buffer the underlying soil against warm season air temperatures and thus increased SOC decomposition as indicated by the higher oxidation of SOC molecules and a lower contribution of simple molecules under open cover than the closed canopy sites. Our findings suggest that the role of canopy cover in SOC dynamics varies as a function of landscape position and soil properties, namely, organic mat thickness and soil moisture. Condition‐specific heterogeneity of SOC composition under open and closed canopy cover highlights the protective effect of canopy cover for soils on backslope positions.
{"title":"Topography and canopy cover influence soil organic carbon composition and distribution across a forested hillslope in the discontinuous permafrost zone","authors":"Erin C. Rooney, V. Bailey, Kaizad F. Patel, A. Kholodov, H. Golightly, R. Lybrand","doi":"10.1002/ppp.2200","DOIUrl":"https://doi.org/10.1002/ppp.2200","url":null,"abstract":"Topography and canopy cover influence ground temperature in warming permafrost landscapes, yet soil temperature heterogeneity introduced by mesotopographic slope positions, microtopographic differences in vegetation cover, and the subsequent impact of contrasting temperature conditions on soil organic carbon (SOC) dynamics are understudied. Buffering of permafrost‐affected soils against warming air temperatures in boreal forests can reflect surface soil characteristics (e.g., thickness of organic material) as well as the degree and type of canopy cover (e.g., open cover vs. closed cover). Both landscape and soil properties interact to determine meso‐ and microscale heterogeneity of ground warming. We sampled a hillslope catena transect in a discontinuous permafrost zone near Fairbanks, Alaska, to test the small‐scale (1 to 3 m) impacts of slope position and cover type on soil organic matter composition. Mineral active layer samples were collected from backslope, low backslope, and footslope positions at depths spanning 19 to 60 cm. We examined soil mineralogical composition, soil moisture, total carbon and nitrogen content, and organic mat thickness in conjunction with an assessment of SOC composition using Fourier‐transform ion cyclotron resonance mass spectrometry (FT‐ICR‐MS). Soils in the footslope position had a higher relative contribution of lignin‐like compounds, whereas backslope soils had more aliphatic and condensed aromatic compounds as determined using FT‐ICR‐MS. The effect of open versus closed tree canopy cover varied with the slope position. On the backslope, we found higher oxidation of molecules under open cover than closed cover, indicating an effect of warmer soil temperature on decomposition. Little to no effect of the canopy was observed in soils at the footslope position, which we attributed, in part, to the strong impact of soil moisture content in SOC dynamics in the water‐gathering footslope position. The thin organic mat under open cover on the backslope position may have contributed to differences in soil temperature and thus SOC oxidation under open and closed canopies. Here, the thinner organic mat did not appear to buffer the underlying soil against warm season air temperatures and thus increased SOC decomposition as indicated by the higher oxidation of SOC molecules and a lower contribution of simple molecules under open cover than the closed canopy sites. Our findings suggest that the role of canopy cover in SOC dynamics varies as a function of landscape position and soil properties, namely, organic mat thickness and soil moisture. Condition‐specific heterogeneity of SOC composition under open and closed canopy cover highlights the protective effect of canopy cover for soils on backslope positions.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"34 1","pages":"331 - 358"},"PeriodicalIF":5.0,"publicationDate":"2023-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44957697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tadeusz Sokołowski, B. Woronko, Dorota Chmielowska‐Michalak
Coversands (CSs) are one of the most distinctive sediments within the European Sand Belt. Their extraordinary thickness, exceeding 6 m, was recorded at the Góra Motyczna site located at the edge of the Wisłoka River valley in the Tarnów Plateau (southeast Poland). The sedimentary record of the studied CSs sets their arrangement into one of two sedimentary cycles. Each consists of sandy (A1 and A2) and silty (B1 and B2) lithofacies, forming an A1 ⇒ B1 ⇒ A2 ⇒ B2 sequence that is considered to be a record of climate change during the Weichselian Late Pleniglacial. Sandy lithofacies accumulation occurred under dry and snow‐free climatic conditions, whereas silty lithofacies accumulation marks an increase in humidity as a result of the presence of snow‐cover. Sediment optical dating indicated that the studied CSs were deposited in a period from ~18–17 to ~16–15 ka. The period of accumulation was therefore short, which is confirmed by the analysis of quartz‐grain shape and surface type. Due to this brevity of aeolian processes during this period, the only change expressed is in grain‐surface microrelief; thus, the quartz grains had already inherited their shape and degree of rounding from their source environments and earlier processes. The source sediments could have been artefacts of Miocene and Quaternary deflationary sediments associated with blowouts.
{"title":"Climate change records in coversand deposits from the eastern margin of the Tarnów Plateau (southeast Poland)","authors":"Tadeusz Sokołowski, B. Woronko, Dorota Chmielowska‐Michalak","doi":"10.1002/ppp.2199","DOIUrl":"https://doi.org/10.1002/ppp.2199","url":null,"abstract":"Coversands (CSs) are one of the most distinctive sediments within the European Sand Belt. Their extraordinary thickness, exceeding 6 m, was recorded at the Góra Motyczna site located at the edge of the Wisłoka River valley in the Tarnów Plateau (southeast Poland). The sedimentary record of the studied CSs sets their arrangement into one of two sedimentary cycles. Each consists of sandy (A1 and A2) and silty (B1 and B2) lithofacies, forming an A1 ⇒ B1 ⇒ A2 ⇒ B2 sequence that is considered to be a record of climate change during the Weichselian Late Pleniglacial. Sandy lithofacies accumulation occurred under dry and snow‐free climatic conditions, whereas silty lithofacies accumulation marks an increase in humidity as a result of the presence of snow‐cover. Sediment optical dating indicated that the studied CSs were deposited in a period from ~18–17 to ~16–15 ka. The period of accumulation was therefore short, which is confirmed by the analysis of quartz‐grain shape and surface type. Due to this brevity of aeolian processes during this period, the only change expressed is in grain‐surface microrelief; thus, the quartz grains had already inherited their shape and degree of rounding from their source environments and earlier processes. The source sediments could have been artefacts of Miocene and Quaternary deflationary sediments associated with blowouts.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"34 1","pages":"428 - 447"},"PeriodicalIF":5.0,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46201574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Issue Information","authors":"","doi":"10.1002/ppp.2154","DOIUrl":"https://doi.org/10.1002/ppp.2154","url":null,"abstract":"No abstract is available for this article.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":" ","pages":""},"PeriodicalIF":5.0,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44929707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Murton, T. Opel, S. Wetterich, K. Ashastina, G. Savvinov, P. Danilov, V. Boeskorov
The Batagay megaslump, in the Yana Uplands of northern Yakutia, Russia, is the largest known retrogressive thaw slump in the world. The slump exposes a remarkable sequence of Ice Age permafrost deposits that record the interaction of colluvial, eolian and periglacial processes on a hillslope episodically forested during the last 650 ka or more in response to climate variability on glacial–interglacial timescales. Numerous bones, teeth, and occasional carcasses of Pleistocene and Holocene mammals have been recovered from the permafrost. The megaslump developed over the course of several decades in three stages: (1) gullying, (2) thaw slumping, and (3) megaslumping. After disturbance to the taiga vegetation cover in the 1940s–1960s, a hillslope gully formed by the early 1960s. The gully initiated thaw slumping along its central part during the 1980s, with the slump enlarging to megaslump (>20 ha) proportions during the 1990s. By 2019, the area of the slump had reached about 80 ha and its headwall above the slump floor was up to about 55 m high. The main geomorphic processes of slump growth are headwall ablation and thermal erosion, producing a distinctive terrain of icy badlands on the slump floor. Though much of the megaslump is rapidly growing at present, it will probably stabilize eventually as an irregular terrain characterized by sandy ridges and sand‐filled elongate depressions formed by degradation of the badlands. Comparison of the Batagay megaslump with megaslumps from northwest Canada reveals several similarities and differences in terms of their geomorphology, permafrost deposits, and Quaternary history.
{"title":"Batagay megaslump: A review of the permafrost deposits, Quaternary environmental history, and recent development","authors":"J. Murton, T. Opel, S. Wetterich, K. Ashastina, G. Savvinov, P. Danilov, V. Boeskorov","doi":"10.1002/ppp.2194","DOIUrl":"https://doi.org/10.1002/ppp.2194","url":null,"abstract":"The Batagay megaslump, in the Yana Uplands of northern Yakutia, Russia, is the largest known retrogressive thaw slump in the world. The slump exposes a remarkable sequence of Ice Age permafrost deposits that record the interaction of colluvial, eolian and periglacial processes on a hillslope episodically forested during the last 650 ka or more in response to climate variability on glacial–interglacial timescales. Numerous bones, teeth, and occasional carcasses of Pleistocene and Holocene mammals have been recovered from the permafrost. The megaslump developed over the course of several decades in three stages: (1) gullying, (2) thaw slumping, and (3) megaslumping. After disturbance to the taiga vegetation cover in the 1940s–1960s, a hillslope gully formed by the early 1960s. The gully initiated thaw slumping along its central part during the 1980s, with the slump enlarging to megaslump (>20 ha) proportions during the 1990s. By 2019, the area of the slump had reached about 80 ha and its headwall above the slump floor was up to about 55 m high. The main geomorphic processes of slump growth are headwall ablation and thermal erosion, producing a distinctive terrain of icy badlands on the slump floor. Though much of the megaslump is rapidly growing at present, it will probably stabilize eventually as an irregular terrain characterized by sandy ridges and sand‐filled elongate depressions formed by degradation of the badlands. Comparison of the Batagay megaslump with megaslumps from northwest Canada reveals several similarities and differences in terms of their geomorphology, permafrost deposits, and Quaternary history.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"34 1","pages":"399 - 416"},"PeriodicalIF":5.0,"publicationDate":"2023-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43467354","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The mechanisms of sediment removal associated with the nivation process suite are underinvestigated, a situation that hinders development of a unified, coherent theory of cryoplanation terrace formation. This study links sorted stripes—a type of periglacial patterned ground frequently encountered on cryoplanation terrace treads—to active hydrologic networks capable of transporting large quantities of fine sediments on periglacial hillslopes. Traditional interpretations hold that the presence of sorted patterned ground indicates geomorphic quiescence, a view that has contributed to the dismissal of these features as a factor in the formation of erosional periglacial topography. We address the geomorphic role of sorted stripes as fluvial features by investigating their hydrologic potential for transporting weathered material across and off developing cryoplanation terraces. Flow modeling and watershed geomorphometric analyses were conducted using a high‐resolution digital elevation model of a large cryoplanation terrace in a geomorphically active periglacial upland near Atlin, British Columbia, Canada. Results demonstrate the landscape‐scale spatial organization and geomorphic effectiveness of sorted‐stripe networks—“little tools”—for transporting water and suspended sediment across large cryoplanated surfaces. We present a qualitative model of sediment production and transportation, “the periglacial conveyor system,” that outlines erosional processes responsible for cryoplanation terrace formation and defines the distinctive hydrologic–geomorphic imprint imparted by sorted stripes on periglacial hillslopes.
{"title":"Little tools, big job: The periglacial conveyor system in cryoplanated uplands","authors":"Raven J. Mitchell, F. Nelson, K. Nyland","doi":"10.1002/ppp.2193","DOIUrl":"https://doi.org/10.1002/ppp.2193","url":null,"abstract":"The mechanisms of sediment removal associated with the nivation process suite are underinvestigated, a situation that hinders development of a unified, coherent theory of cryoplanation terrace formation. This study links sorted stripes—a type of periglacial patterned ground frequently encountered on cryoplanation terrace treads—to active hydrologic networks capable of transporting large quantities of fine sediments on periglacial hillslopes. Traditional interpretations hold that the presence of sorted patterned ground indicates geomorphic quiescence, a view that has contributed to the dismissal of these features as a factor in the formation of erosional periglacial topography. We address the geomorphic role of sorted stripes as fluvial features by investigating their hydrologic potential for transporting weathered material across and off developing cryoplanation terraces. Flow modeling and watershed geomorphometric analyses were conducted using a high‐resolution digital elevation model of a large cryoplanation terrace in a geomorphically active periglacial upland near Atlin, British Columbia, Canada. Results demonstrate the landscape‐scale spatial organization and geomorphic effectiveness of sorted‐stripe networks—“little tools”—for transporting water and suspended sediment across large cryoplanated surfaces. We present a qualitative model of sediment production and transportation, “the periglacial conveyor system,” that outlines erosional processes responsible for cryoplanation terrace formation and defines the distinctive hydrologic–geomorphic imprint imparted by sorted stripes on periglacial hillslopes.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"34 1","pages":"384 - 398"},"PeriodicalIF":5.0,"publicationDate":"2023-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41391143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rock glaciers are the most common landforms of the Andean periglacial landscape in the Central Andes of San Juan, Argentina. Their active layer is gravelly with a typical openwork structure. The upper parts of these rock glaciers are coarse‐grained Turbic Cryosols, with no vegetation cover. Since March 2018, coarse soils in the active layer of the “Candidato” rock glacier have been monitored (31.9°S, 70.18°W). Three trenches, 4,000 m a.s.l. and down to a depth of 90 cm, were equipped with sensors to measure soil temperature and volumetric water content. We also measured particle size distributions and calculated thermal properties from soil samples. The mean thermal conductivities for unfrozen and frozen soils were 0.69 and 0.54 W m−1 K−1, respectively, and the mean thermal diffusivities were 2.05 × 10−7 and 1.64 × 10–7 m2 s−1, respectively. Analysis of the seasonal thermal and hydrological fluxes in the active layer is challenging, as the physical properties change cyclically, thus controlling processes such as water storage, infiltration and seepage, heat balance, mechanical behavior, and kinematic response. We used the Coupled Heat and Mass Transfer Model for the Soil–Plant–Atmosphere System (COUP) numerical computerized model, performing a site‐specific calibration, to simulate soil temperatures, active layer thicknesses, and seasonal freezing–thawing depths. The model implemented, in combination with a reanalysis of the meteorological data series, performed very well to reproduce the data from thermo‐sensors placed in the ground. This proposed methodology is viable for areas with limited instrumentation or low accessibility. The “Candidato” rock glacier can be used as a pilot model for thermal modeling purposes on rhyolitic rock glaciers in the region.
{"title":"Thermal simulations on periglacial soils of the Central Andes, Argentina","authors":"Martín Mendoza López, Carla Tapia Baldis, Darío Trombotto Liaudat, Noelia R Sileo","doi":"10.1002/ppp.2189","DOIUrl":"https://doi.org/10.1002/ppp.2189","url":null,"abstract":"Rock glaciers are the most common landforms of the Andean periglacial landscape in the Central Andes of San Juan, Argentina. Their active layer is gravelly with a typical openwork structure. The upper parts of these rock glaciers are coarse‐grained Turbic Cryosols, with no vegetation cover. Since March 2018, coarse soils in the active layer of the “Candidato” rock glacier have been monitored (31.9°S, 70.18°W). Three trenches, 4,000 m a.s.l. and down to a depth of 90 cm, were equipped with sensors to measure soil temperature and volumetric water content. We also measured particle size distributions and calculated thermal properties from soil samples. The mean thermal conductivities for unfrozen and frozen soils were 0.69 and 0.54 W m−1 K−1, respectively, and the mean thermal diffusivities were 2.05 × 10−7 and 1.64 × 10–7 m2 s−1, respectively. Analysis of the seasonal thermal and hydrological fluxes in the active layer is challenging, as the physical properties change cyclically, thus controlling processes such as water storage, infiltration and seepage, heat balance, mechanical behavior, and kinematic response. We used the Coupled Heat and Mass Transfer Model for the Soil–Plant–Atmosphere System (COUP) numerical computerized model, performing a site‐specific calibration, to simulate soil temperatures, active layer thicknesses, and seasonal freezing–thawing depths. The model implemented, in combination with a reanalysis of the meteorological data series, performed very well to reproduce the data from thermo‐sensors placed in the ground. This proposed methodology is viable for areas with limited instrumentation or low accessibility. The “Candidato” rock glacier can be used as a pilot model for thermal modeling purposes on rhyolitic rock glaciers in the region.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"34 1","pages":"296 - 316"},"PeriodicalIF":5.0,"publicationDate":"2023-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46084702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Eleanor L. Jones, A. Hodson, K. Redeker, H. Christiansen, S. Thornton, Jade Rogers
Arctic wetlands are a globally significant store of soil organic carbon. They are often characterized by ice‐wedge polygons, which are diagnostic of lowland permafrost, and which greatly influence wetland hydrology and biogeochemistry during summer. The degradation of ice‐wedge polygons, which can occur in response to climate change or local disturbance, has poorly understood consequences for biogeochemical processes. We therefore used geochemical analyses from the active layer and top permafrost to identify and compare the dominant biogeochemical processes in high‐centered (degraded) and low‐centered (pristine) polygons situated in the raised beach sediments and valley‐infill sediments of Adventdalen, Central Svalbard. We found similar organic‐rich sediments in both cases (up to 38 dry wt.%), but while low‐centered polygons were water‐saturated, their high‐centered counterparts had a relatively dry active layer. Consequently, low‐centered polygons showed evidence of iron and sulfate reduction leading to the precipitation of pyrite and siderite, whilst the high‐centered polygons demonstrated more oxidizing conditions, with decreased iron oxidation and low preservation of iron and sulfate reduction products in the sediments. This study thus demonstrates the profound effect of ice‐wedge polygon degradation on the redox chemistry of the host sediment and porewater, namely more oxidizing conditions, a decrease in iron reduction, and a decrease in the preservation of iron and sulfate reduction products.
{"title":"Biogeochemistry of low‐ and high‐centered ice‐wedge polygons in wetlands in Svalbard","authors":"Eleanor L. Jones, A. Hodson, K. Redeker, H. Christiansen, S. Thornton, Jade Rogers","doi":"10.1002/ppp.2192","DOIUrl":"https://doi.org/10.1002/ppp.2192","url":null,"abstract":"Arctic wetlands are a globally significant store of soil organic carbon. They are often characterized by ice‐wedge polygons, which are diagnostic of lowland permafrost, and which greatly influence wetland hydrology and biogeochemistry during summer. The degradation of ice‐wedge polygons, which can occur in response to climate change or local disturbance, has poorly understood consequences for biogeochemical processes. We therefore used geochemical analyses from the active layer and top permafrost to identify and compare the dominant biogeochemical processes in high‐centered (degraded) and low‐centered (pristine) polygons situated in the raised beach sediments and valley‐infill sediments of Adventdalen, Central Svalbard. We found similar organic‐rich sediments in both cases (up to 38 dry wt.%), but while low‐centered polygons were water‐saturated, their high‐centered counterparts had a relatively dry active layer. Consequently, low‐centered polygons showed evidence of iron and sulfate reduction leading to the precipitation of pyrite and siderite, whilst the high‐centered polygons demonstrated more oxidizing conditions, with decreased iron oxidation and low preservation of iron and sulfate reduction products in the sediments. This study thus demonstrates the profound effect of ice‐wedge polygon degradation on the redox chemistry of the host sediment and porewater, namely more oxidizing conditions, a decrease in iron reduction, and a decrease in the preservation of iron and sulfate reduction products.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"34 1","pages":"359 - 369"},"PeriodicalIF":5.0,"publicationDate":"2023-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44469485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
One of the most important problems of cryopedology is the interaction of pedogenic processes with the processes that form the structure of the uppermost layers of the near‐surface permafrost. The thickness, structure, spatial variability, and other features are responsible for the reaction of the soil‐permafrost system to the bioclimatic fluctuations as well as the contemporary anthropogenic pressure. Together the soil profile and the upper layers of permafrost form the natural body of the “soil–cryogenic complex,” which is the result of simultaneous late Pleistocene–Holocene soil and permafrost coevolution. Pedogenic and cryogenic processes together form organic‐accumulative horizons above the permafrost table that have often been described in the profiles of Cryosols in different regions of Arctic. The multiannual dynamics of summer thawing depth determine the involvement of the material of these shielding horizons into the zone of active modern pedogenesis or its exclusion from it in case of their frozen state. Soil surface microrelief, complexity of the vegetation, and spatial differences of thermal properties of the suprapermafrost soil horizons and the transient layer of permafrost are responsible for the complicated pattern of permafrost table microrelief. Thus, the long‐term study of cryogenic soils that are developed on the close underlying permafrost provides improved understanding of the natural‐historical body—soil‐cryogenic complex.
{"title":"The soil–cryogenic complex: Evidence of late Pleistocene–Holocene coevolution of permafrost and cryosols at the Kolyma Lowland","authors":"A. Lupachev, S. Gubin","doi":"10.1002/ppp.2191","DOIUrl":"https://doi.org/10.1002/ppp.2191","url":null,"abstract":"One of the most important problems of cryopedology is the interaction of pedogenic processes with the processes that form the structure of the uppermost layers of the near‐surface permafrost. The thickness, structure, spatial variability, and other features are responsible for the reaction of the soil‐permafrost system to the bioclimatic fluctuations as well as the contemporary anthropogenic pressure. Together the soil profile and the upper layers of permafrost form the natural body of the “soil–cryogenic complex,” which is the result of simultaneous late Pleistocene–Holocene soil and permafrost coevolution. Pedogenic and cryogenic processes together form organic‐accumulative horizons above the permafrost table that have often been described in the profiles of Cryosols in different regions of Arctic. The multiannual dynamics of summer thawing depth determine the involvement of the material of these shielding horizons into the zone of active modern pedogenesis or its exclusion from it in case of their frozen state. Soil surface microrelief, complexity of the vegetation, and spatial differences of thermal properties of the suprapermafrost soil horizons and the transient layer of permafrost are responsible for the complicated pattern of permafrost table microrelief. Thus, the long‐term study of cryogenic soils that are developed on the close underlying permafrost provides improved understanding of the natural‐historical body—soil‐cryogenic complex.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"34 1","pages":"317 - 330"},"PeriodicalIF":5.0,"publicationDate":"2023-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46245692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Beáta Farkas, G. Sipos, Tamás Bartyik, E. Józsa, S. Czigány, Richárd Balogh, G. Varga, János Kovács, S. Fábián
The Pannonian Basin was located in the southernmost, disputed limit of permafrost during the Last Glacial Maximum (LGM). In the western part of the basin, over an area of 1,200 km2, more than 150 sites with polygonal patterned ground were surveyed, and 72 sediment samples from forms identified as relict sand wedges were collected. Ten optically stimulated luminescence ages were obtained from the infills, while morphometric analyses were also carried out on satellite images. Our study revealed that the polygonal networks developed in several phases, from 15.01 ± 1.68 to 23.0 ± 1.7 ka. The polygons have an average diameter of 13–23 m and are mainly present on flat surfaces, intruding into the gravelly, alluvial host of the paleo‐Rába. Statistical analyses highlighted the short transportation period of the sandy infill and multiple sediment provenances. This study adds further data to assess the presence of permafrost or deep seasonal frost and to the interpretation of the LGM in the central European periglacial domain.
{"title":"Characterization and mapping of MIS‐2 thermal contraction crack polygons in Western Transdanubia, Hungary","authors":"Beáta Farkas, G. Sipos, Tamás Bartyik, E. Józsa, S. Czigány, Richárd Balogh, G. Varga, János Kovács, S. Fábián","doi":"10.1002/ppp.2190","DOIUrl":"https://doi.org/10.1002/ppp.2190","url":null,"abstract":"The Pannonian Basin was located in the southernmost, disputed limit of permafrost during the Last Glacial Maximum (LGM). In the western part of the basin, over an area of 1,200 km2, more than 150 sites with polygonal patterned ground were surveyed, and 72 sediment samples from forms identified as relict sand wedges were collected. Ten optically stimulated luminescence ages were obtained from the infills, while morphometric analyses were also carried out on satellite images. Our study revealed that the polygonal networks developed in several phases, from 15.01 ± 1.68 to 23.0 ± 1.7 ka. The polygons have an average diameter of 13–23 m and are mainly present on flat surfaces, intruding into the gravelly, alluvial host of the paleo‐Rába. Statistical analyses highlighted the short transportation period of the sandy infill and multiple sediment provenances. This study adds further data to assess the presence of permafrost or deep seasonal frost and to the interpretation of the LGM in the central European periglacial domain.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"34 1","pages":"417 - 427"},"PeriodicalIF":5.0,"publicationDate":"2023-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41415012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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