Saize Zhang, F. Niu, Shi Wang, Y. Sun, Jinchang Wang, Tian-Tian Dong
The embankment–bridge transition section (EBTS) is one of the zones where railway diseases occur frequently in permafrost regions. Disease risk assessment of EBTSs can provide guidance for maintenance. In this study, considering the engineering geological conditions, climate characteristics, and embankment structure types along the Qinghai–Tibet Railway (QTR) as well as based on the disease inventory of the QTR from 2010 to 2019, the logistic regression (LR), support vector machine (SVM), and combination‐weight‐based gay relation analysis (GRA) were used for disease risk assessment of the EBTSs along the QTR in permafrost regions. The results indicate that the LR and SVM models have a better capability for EBTS disease prediction than the GRA model, and the SVM model can select more disease samples in relatively larger regions than the LR model. Based on the SVM and LR models, the risk level of EBTSs is divided into four classes: low‐ (29.9%), moderate‐ (39.6%), high‐ (22.1%), and very high (8.4%) risk. Finally, we selected 272 EBTSs in high‐ and very‐high‐risk classes for key observation during the maintenance of the QTR in permafrost regions. This study provides a reference for the risk assessment of railways built in permafrost regions using data‐driven methods.
{"title":"Risk assessment of engineering diseases of embankment–bridge transition section for railway in permafrost regions","authors":"Saize Zhang, F. Niu, Shi Wang, Y. Sun, Jinchang Wang, Tian-Tian Dong","doi":"10.1002/ppp.2135","DOIUrl":"https://doi.org/10.1002/ppp.2135","url":null,"abstract":"The embankment–bridge transition section (EBTS) is one of the zones where railway diseases occur frequently in permafrost regions. Disease risk assessment of EBTSs can provide guidance for maintenance. In this study, considering the engineering geological conditions, climate characteristics, and embankment structure types along the Qinghai–Tibet Railway (QTR) as well as based on the disease inventory of the QTR from 2010 to 2019, the logistic regression (LR), support vector machine (SVM), and combination‐weight‐based gay relation analysis (GRA) were used for disease risk assessment of the EBTSs along the QTR in permafrost regions. The results indicate that the LR and SVM models have a better capability for EBTS disease prediction than the GRA model, and the SVM model can select more disease samples in relatively larger regions than the LR model. Based on the SVM and LR models, the risk level of EBTSs is divided into four classes: low‐ (29.9%), moderate‐ (39.6%), high‐ (22.1%), and very high (8.4%) risk. Finally, we selected 272 EBTSs in high‐ and very‐high‐risk classes for key observation during the maintenance of the QTR in permafrost regions. This study provides a reference for the risk assessment of railways built in permafrost regions using data‐driven methods.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"33 1","pages":"46 - 62"},"PeriodicalIF":5.0,"publicationDate":"2021-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47681676","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}
Within the Canadian Arctic, vast areas of previously frozen sediments and carbon are being released into aquatic ecosystems via the occurrence of permafrost thaw and retrogressive thaw slumps (RTSs). While knowledge of mass wasting RTS processes are more advanced, the significance of exposed retrogressive thaw slump scars (RTSSs) at various phases of stabilization to yield additional large quantities of ecologically relevant sediment to lakes and rivers is not well constrained. Using laboratory simulation (linked rainfall and lake flow dynamics), RTS sediments were investigated to assess the sediment continuum from the terrestrial RTSSs to depositional zones within two Arctic tundra lakes. Using an estimate of 30% of the RTSS areas contributing sediment under hypothetical 20‐ and 100‐year rainfall events, up to 598 and 997 kg hr−1 of RTSS sediment washoff was projected respectively. Eroded particle size, regardless of lake or initial bulk RTSS size distribution, was dominated by individual clay particles (<5 μm) that were winnowed from the RTSS surface sediment. Given this is the most biogeochemical relevant fraction, it has the potential for significant ecological impact on the lakes. This deposited fine sediment was found to be very unstable with a critical shear stress for erosion close to that of the critical shear for deposition (0.05 Pa). As such, wave energy is expected to have an impact on remobilization of fine sediments and associated compounds with concomitant implications for lake‐ecosystem health.
在加拿大的北极地区，由于永久冻土解冻和退行性解冻滑坡(RTSs)的发生，大量以前冻结的沉积物和碳被释放到水生生态系统中。虽然对大规模浪费的RTS过程的了解更加先进，但暴露的后退性融化滑塌疤痕(RTSSs)在稳定的各个阶段对湖泊和河流产生额外的大量生态相关沉积物的重要性并没有得到很好的限制。利用室内模拟(关联降雨和湖泊流动动力学)，研究了两个北极冻土带湖泊从陆地rtss到沉积带的沉积物连续体。在假设的20年和100年降雨事件下，利用30%的RTSS地区贡献泥沙的估计，分别预测了高达598和997 kg hr - 1的RTSS泥沙冲量。无论湖泊还是初始体积RTSS粒度分布，侵蚀粒度都以从RTSS表层沉积物中筛选出来的单个粘土颗粒(<5 μm)为主。鉴于这是与生物地球化学最相关的部分，它对湖泊有潜在的重大生态影响。沉积的细粒沉积物非常不稳定，侵蚀临界剪切应力接近沉积临界剪切应力(0.05 Pa)。因此，波浪能有望对细沉积物和相关化合物的再活化产生影响，并对湖泊生态系统的健康产生影响。
{"title":"Assessment of the sediment and associated nutrient/contaminant continuum, from permafrost thaw slump scars to tundra lakes in the western Canadian Arctic","authors":"I. Droppo, P. Cenzo, Renée McFadyen, Thomas Reid","doi":"10.1002/ppp.2134","DOIUrl":"https://doi.org/10.1002/ppp.2134","url":null,"abstract":"Within the Canadian Arctic, vast areas of previously frozen sediments and carbon are being released into aquatic ecosystems via the occurrence of permafrost thaw and retrogressive thaw slumps (RTSs). While knowledge of mass wasting RTS processes are more advanced, the significance of exposed retrogressive thaw slump scars (RTSSs) at various phases of stabilization to yield additional large quantities of ecologically relevant sediment to lakes and rivers is not well constrained. Using laboratory simulation (linked rainfall and lake flow dynamics), RTS sediments were investigated to assess the sediment continuum from the terrestrial RTSSs to depositional zones within two Arctic tundra lakes. Using an estimate of 30% of the RTSS areas contributing sediment under hypothetical 20‐ and 100‐year rainfall events, up to 598 and 997 kg hr−1 of RTSS sediment washoff was projected respectively. Eroded particle size, regardless of lake or initial bulk RTSS size distribution, was dominated by individual clay particles (<5 μm) that were winnowed from the RTSS surface sediment. Given this is the most biogeochemical relevant fraction, it has the potential for significant ecological impact on the lakes. This deposited fine sediment was found to be very unstable with a critical shear stress for erosion close to that of the critical shear for deposition (0.05 Pa). As such, wave energy is expected to have an impact on remobilization of fine sediments and associated compounds with concomitant implications for lake‐ecosystem health.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"33 1","pages":"32 - 45"},"PeriodicalIF":5.0,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42746152","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 cryosphere hosts a widespread microbial community, yet microbial influences on silicate weathering have been historically neglected in cold‐arid deserts. Here we investigate bioweathering by a cold‐tolerant cyanobacteria (Leptolyngbya glacialis) via laboratory experiments using glaciofluvial drift sediments at 12°C, analogous to predicted future permafrost surface temperatures. Our results show threefold enhanced Si weathering rates in pre‐weathered, mixed‐lithology Antarctic biotic reactors compared to abiotic controls, indicating the significant influence of microbial life on weathering. Although biotic and abiotic weathering rates are similar in Icelandic sediments, neo‐formed clay and Fe‐(oxy)hydroxide minerals observed in association with biofilms in biotic reactors are common on Icelandic mafic minerals, similar to features observed in unprocessed Antarctic drifts. This suggests that microbes enhance weathering in systems where they must scavenge for nutrients that are not easily liberated via abiotic pathways; potential biosignatures may form in nutrient‐rich systems as well. In both sediment types we also observed up to fourfold higher bicarbonate concentrations in biotic reactors relative to abiotic reactors, indicating that, as warming occurs, psychrotolerant biota will enhance bicarbonate flux to the oceans, thus stimulating carbonate deposition and providing a negative feedback to increasing atmospheric CO2.
{"title":"Cyanobacterial weathering in warming periglacial sediments: Implications for nutrient cycling and potential biosignatures","authors":"C. Demirel‐Floyd, G. Soreghan, M. Madden","doi":"10.1002/ppp.2133","DOIUrl":"https://doi.org/10.1002/ppp.2133","url":null,"abstract":"The cryosphere hosts a widespread microbial community, yet microbial influences on silicate weathering have been historically neglected in cold‐arid deserts. Here we investigate bioweathering by a cold‐tolerant cyanobacteria (Leptolyngbya glacialis) via laboratory experiments using glaciofluvial drift sediments at 12°C, analogous to predicted future permafrost surface temperatures. Our results show threefold enhanced Si weathering rates in pre‐weathered, mixed‐lithology Antarctic biotic reactors compared to abiotic controls, indicating the significant influence of microbial life on weathering. Although biotic and abiotic weathering rates are similar in Icelandic sediments, neo‐formed clay and Fe‐(oxy)hydroxide minerals observed in association with biofilms in biotic reactors are common on Icelandic mafic minerals, similar to features observed in unprocessed Antarctic drifts. This suggests that microbes enhance weathering in systems where they must scavenge for nutrients that are not easily liberated via abiotic pathways; potential biosignatures may form in nutrient‐rich systems as well. In both sediment types we also observed up to fourfold higher bicarbonate concentrations in biotic reactors relative to abiotic reactors, indicating that, as warming occurs, psychrotolerant biota will enhance bicarbonate flux to the oceans, thus stimulating carbonate deposition and providing a negative feedback to increasing atmospheric CO2.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"33 1","pages":"63 - 77"},"PeriodicalIF":5.0,"publicationDate":"2021-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42019042","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}
C. D. Villarroel, Diana Agostina Ortiz, A. Forte, Guillermo Tamburini Beliveau, D. Ponce, A. Imhof, Andrés López
This paper presents an analysis of the internal structure, hydrogeology and dynamics of a large, complex, multilobate and multiroot rock glacier combining electrical resistivity tomography (ERT), hydrochemical data and differential interferometry synthetic aperture radar (DInSAR). The rock glacier consists of a series of overlapping lobes that represent different advancing stages with different degrees of conservation. The ERT surveys characterize the active layer and the upper part of the permafrost layer, the latter showing a heterogeneous geometry and electrical resistivity values ranging from 7 to 142 kΩm. Hydrochemical data argue for both the existence of different disconnected water flow pathways inside the rock glacier and the remarkable ionic concentrator effect of this landform. The horizontal displacement from October 2014 to April 2017 shows greatest magnitudes in the upper sector of both tongues, reaching speeds of up to 150 cm/year. The active frontal sector shows a displacement rate of 2–4.5 cm/year. This study contributes to knowledge of the material properties of rock glaciers, which are considered to represent important reservoirs/water resources, and their influence on the distribution of mountain permafrost, hydrology, and dynamics. Finally, to the best of our knowledge, the possible influence of the metal content of the ground on the resistivity values recorded for mountain permafrost is highlighted for the first time.
{"title":"Internal structure of a large, complex rock glacier and its significance in hydrological and dynamic behavior: A case study in the semi‐arid Andes of Argentina","authors":"C. D. Villarroel, Diana Agostina Ortiz, A. Forte, Guillermo Tamburini Beliveau, D. Ponce, A. Imhof, Andrés López","doi":"10.1002/ppp.2132","DOIUrl":"https://doi.org/10.1002/ppp.2132","url":null,"abstract":"This paper presents an analysis of the internal structure, hydrogeology and dynamics of a large, complex, multilobate and multiroot rock glacier combining electrical resistivity tomography (ERT), hydrochemical data and differential interferometry synthetic aperture radar (DInSAR). The rock glacier consists of a series of overlapping lobes that represent different advancing stages with different degrees of conservation. The ERT surveys characterize the active layer and the upper part of the permafrost layer, the latter showing a heterogeneous geometry and electrical resistivity values ranging from 7 to 142 kΩm. Hydrochemical data argue for both the existence of different disconnected water flow pathways inside the rock glacier and the remarkable ionic concentrator effect of this landform. The horizontal displacement from October 2014 to April 2017 shows greatest magnitudes in the upper sector of both tongues, reaching speeds of up to 150 cm/year. The active frontal sector shows a displacement rate of 2–4.5 cm/year. This study contributes to knowledge of the material properties of rock glaciers, which are considered to represent important reservoirs/water resources, and their influence on the distribution of mountain permafrost, hydrology, and dynamics. Finally, to the best of our knowledge, the possible influence of the metal content of the ground on the resistivity values recorded for mountain permafrost is highlighted for the first time.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"33 1","pages":"78 - 95"},"PeriodicalIF":5.0,"publicationDate":"2021-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41498197","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}
Ice wedges in the Holocene deposits of alases and floodplains have been studied in the Kolyma Lowland region. Most ice wedges have been found within alases dated to between 11 and 4.2 cal kyr BP, corresponding to the Greenlandian and Northgrippian stages of the Holocene. This study confirms that the greatest intensity of ice wedge growth occurred during ~10.5–6 cal kyr BP. A decrease in their growth was mainly caused by alas draining and reduced sedimentation. In the last 4–4.5 cal kyr BP (defined as the Meghalayan stage of the Holocene), ice wedges continued to grow in old alases, sometimes as a younger generation, as well as within young alases and floodplains of the Kolyma River and its tributaries. Mean January air temperatures were quite stable during the Holocene and varied usually approximately between −33 and −41°C, with a slight cooling during the Meghalayan stage. Minor variations in mean January air temperature may indicate a stability of winter climate of northern Yakutia, probably as a result of the stable influence of the Siberian anticyclone.
对Kolyma低地全新世阿拉斯加和泛滥平原沉积物中的冰楔进行了研究。大多数冰楔是在阿拉斯加发现的，可追溯到11至4.2 cal kyr BP，对应于全新世的格陵兰和北格里普阶。这项研究证实，冰楔生长的最大强度发生在约10.5–6 cal kyr BP期间。它们的生长减少主要是由于阿拉斯加州的排水和沉积减少造成的。在最近的4–4.5 cal kyr BP（定义为全新世的梅加拉亚阶）中，冰楔继续在旧阿拉斯加生长，有时是年轻一代，以及在科莱马河及其支流的年轻阿拉斯加和泛滥平原内生长。1月的平均气温在全新世期间相当稳定，通常在−33和−41°C之间变化，梅加拉亚期略有降温。1月平均气温的微小变化可能表明雅库特北部冬季气候的稳定，这可能是西伯利亚反气旋稳定影响的结果。
{"title":"Holocene ice wedges of the Kolyma Lowland and January paleotemperature reconstructions based on oxygen isotope records","authors":"Y. Vasil'chuk, N. Budantseva","doi":"10.1002/ppp.2128","DOIUrl":"https://doi.org/10.1002/ppp.2128","url":null,"abstract":"Ice wedges in the Holocene deposits of alases and floodplains have been studied in the Kolyma Lowland region. Most ice wedges have been found within alases dated to between 11 and 4.2 cal kyr BP, corresponding to the Greenlandian and Northgrippian stages of the Holocene. This study confirms that the greatest intensity of ice wedge growth occurred during ~10.5–6 cal kyr BP. A decrease in their growth was mainly caused by alas draining and reduced sedimentation. In the last 4–4.5 cal kyr BP (defined as the Meghalayan stage of the Holocene), ice wedges continued to grow in old alases, sometimes as a younger generation, as well as within young alases and floodplains of the Kolyma River and its tributaries. Mean January air temperatures were quite stable during the Holocene and varied usually approximately between −33 and −41°C, with a slight cooling during the Meghalayan stage. Minor variations in mean January air temperature may indicate a stability of winter climate of northern Yakutia, probably as a result of the stable influence of the Siberian anticyclone.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"33 1","pages":"17 - 3"},"PeriodicalIF":5.0,"publicationDate":"2021-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48351538","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}
Zhizhong Sun, Shujuan Zhang, Guo-yu Li, Guilong Wu, Yongzhi Liu
Thermokarst lakes are distributed widely in permafrost regions on the Qinghai–Tibet Plateau (QTP), China. Better knowledge of ground thermal variability beneath and around thermokarst lakes is important for understanding future landscape development and hydrological changes. At a typical undisturbed small, shallow, alpine thermokarst lake in the Beiluhe Basin on the QTP, ground temperatures beneath and adjacent to the lake were monitored at four locations with maximum 30 m depth from the lake center to natural ground. The lake is elliptical with an area of ~700 m2 and maximum water depth of 0.6 m. Permafrost was present beneath and adjacent to the lake during the monitoring period. However, supra‐taliks were present above the permafrost table beneath the lake before monitoring of ground temperature began, but were absent around the lake. The supra‐permafrost taliks beneath the lake have thickened over time. The difference in mean permafrost table depth between the lake center and natural ground reached 5.14 m, and permafrost table depths increased beneath the lake, but changed indistinctively around the lake. Mean annual ground temperatures at different depths (5, 10, 20 and 30 m) were higher beneath the lake than around the lake, and mean increasing rates of ground temperature were also greater beneath the lake than around the lake. Ground temperature differences between the lake bottom and natural ground surface are important for understanding ground thermal patterns beneath and around thermokarst lakes.
{"title":"A 10‐yr thermal regime of permafrost beneath and adjacent to an alpine thermokarst lake, Beiluhe Basin, Qinghai–Tibet Plateau, China","authors":"Zhizhong Sun, Shujuan Zhang, Guo-yu Li, Guilong Wu, Yongzhi Liu","doi":"10.1002/ppp.2107","DOIUrl":"https://doi.org/10.1002/ppp.2107","url":null,"abstract":"Thermokarst lakes are distributed widely in permafrost regions on the Qinghai–Tibet Plateau (QTP), China. Better knowledge of ground thermal variability beneath and around thermokarst lakes is important for understanding future landscape development and hydrological changes. At a typical undisturbed small, shallow, alpine thermokarst lake in the Beiluhe Basin on the QTP, ground temperatures beneath and adjacent to the lake were monitored at four locations with maximum 30 m depth from the lake center to natural ground. The lake is elliptical with an area of ~700 m2 and maximum water depth of 0.6 m. Permafrost was present beneath and adjacent to the lake during the monitoring period. However, supra‐taliks were present above the permafrost table beneath the lake before monitoring of ground temperature began, but were absent around the lake. The supra‐permafrost taliks beneath the lake have thickened over time. The difference in mean permafrost table depth between the lake center and natural ground reached 5.14 m, and permafrost table depths increased beneath the lake, but changed indistinctively around the lake. Mean annual ground temperatures at different depths (5, 10, 20 and 30 m) were higher beneath the lake than around the lake, and mean increasing rates of ground temperature were also greater beneath the lake than around the lake. Ground temperature differences between the lake bottom and natural ground surface are important for understanding ground thermal patterns beneath and around thermokarst lakes.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"32 1","pages":"618 - 626"},"PeriodicalIF":5.0,"publicationDate":"2021-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ppp.2107","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43552126","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}
Sizhong Yang, S. Liebner, Josefine Walz, C. Knoblauch, Till L. V. Bornemann, Alexander J. Probst, D. Wagner, M. Jetten, M. H. Zandt
Permafrost (PF)‐affected soils are widespread in the Arctic and store about half the global soil organic carbon. This large carbon pool becomes vulnerable to microbial decomposition through PF warming and deepening of the seasonal thaw layer (active layer [AL]). Here we combined greenhouse gas (GHG) production rate measurements with a metagenome‐based assessment of the microbial taxonomic and metabolic potential before and after 5 years of incubation under anoxic conditions at a constant temperature of 4°C in the AL, PF transition layer, and intact PF. Warming led to a rapid initial release of CO2 and, to a lesser extent, CH4 in all layers. After the initial pulse, especially in CO2 production, GHG production rates declined and conditions became more methanogenic. Functional gene‐based analyses indicated a decrease in carbon‐ and nitrogen‐cycling genes and a community shift to the degradation of less‐labile organic matter. This study reveals low but continuous GHG production in long‐term warming scenarios, which coincides with a decrease in the relative abundance of major metabolic pathway genes and an increase in carbohydrate‐active enzyme classes.
{"title":"Effects of a long‐term anoxic warming scenario on microbial community structure and functional potential of permafrost‐affected soil","authors":"Sizhong Yang, S. Liebner, Josefine Walz, C. Knoblauch, Till L. V. Bornemann, Alexander J. Probst, D. Wagner, M. Jetten, M. H. Zandt","doi":"10.1002/ppp.2131","DOIUrl":"https://doi.org/10.1002/ppp.2131","url":null,"abstract":"Permafrost (PF)‐affected soils are widespread in the Arctic and store about half the global soil organic carbon. This large carbon pool becomes vulnerable to microbial decomposition through PF warming and deepening of the seasonal thaw layer (active layer [AL]). Here we combined greenhouse gas (GHG) production rate measurements with a metagenome‐based assessment of the microbial taxonomic and metabolic potential before and after 5 years of incubation under anoxic conditions at a constant temperature of 4°C in the AL, PF transition layer, and intact PF. Warming led to a rapid initial release of CO2 and, to a lesser extent, CH4 in all layers. After the initial pulse, especially in CO2 production, GHG production rates declined and conditions became more methanogenic. Functional gene‐based analyses indicated a decrease in carbon‐ and nitrogen‐cycling genes and a community shift to the degradation of less‐labile organic matter. This study reveals low but continuous GHG production in long‐term warming scenarios, which coincides with a decrease in the relative abundance of major metabolic pathway genes and an increase in carbohydrate‐active enzyme classes.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"32 1","pages":"641 - 656"},"PeriodicalIF":5.0,"publicationDate":"2021-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ppp.2131","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45080546","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}
Identifying the changes in thermokarst lake dynamics has a significant contribution to landscape‐scale hydrology, ecology, and assessment of carbon budgets in permafrost regions. Changes in the number and areal extent of thermokarst lakes and ponds were quantified in a representative permafrost area (150 km2) in the south‐central Headwater Area of the Yellow River (HAYR). Water‐body inventories were generated from Landsat satellite imageries using the supervised Maximum Likelihood Classification method for three periods: 1986, 2000, and 2015. From 1986 to 2015, the number of water bodies larger than 0.36 ha decreased by 40% (461–277), while the total surface area decreased by 25% (542–406 ha). The ponds category (smaller than 1 ha) recorded the most substantial change, as their number decreased by 44% and their water‐surface area by 41%. Many lakes disintegrated, partially drained, and formed several remnant ponds, while the majority of the ponds did not drain completely, but shrank below 0.36 ha. These shrinking patterns are consistent with the warming climate in the HAYR, which suggests intense permafrost degradation. Future research will be focused on a better understanding of water–heat dynamics of thermokarst lakes and ponds in association with permafrost degradation at a landscape scale.
{"title":"Shrinking thermokarst lakes and ponds on the northeastern Qinghai‐Tibet plateau over the past three decades","authors":"R. Serban, H. Jin, M. Șerban, D. Luo","doi":"10.1002/ppp.2127","DOIUrl":"https://doi.org/10.1002/ppp.2127","url":null,"abstract":"Identifying the changes in thermokarst lake dynamics has a significant contribution to landscape‐scale hydrology, ecology, and assessment of carbon budgets in permafrost regions. Changes in the number and areal extent of thermokarst lakes and ponds were quantified in a representative permafrost area (150 km2) in the south‐central Headwater Area of the Yellow River (HAYR). Water‐body inventories were generated from Landsat satellite imageries using the supervised Maximum Likelihood Classification method for three periods: 1986, 2000, and 2015. From 1986 to 2015, the number of water bodies larger than 0.36 ha decreased by 40% (461–277), while the total surface area decreased by 25% (542–406 ha). The ponds category (smaller than 1 ha) recorded the most substantial change, as their number decreased by 44% and their water‐surface area by 41%. Many lakes disintegrated, partially drained, and formed several remnant ponds, while the majority of the ponds did not drain completely, but shrank below 0.36 ha. These shrinking patterns are consistent with the warming climate in the HAYR, which suggests intense permafrost degradation. Future research will be focused on a better understanding of water–heat dynamics of thermokarst lakes and ponds in association with permafrost degradation at a landscape scale.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"32 1","pages":"601 - 617"},"PeriodicalIF":5.0,"publicationDate":"2021-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ppp.2127","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41959005","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}
I. Rico, F. Magnin, J. López Moreno, E. Serrano, E. Alonso‐González, J. Revuelto, L. Hughes‐Allen, M. Gómez‐Lende
Permafrost is a relevant component of the Pyrenean high mountains, triggering a wide range of geomorphological cryogenic processes. Although in the past decades there has been an increase in frozen ground studies in the Pyrenees, there are no specific studies about rock wall permafrost, its presence, distribution, thermal regime, or historical evolution. This work combines measured rock surface temperatures (RSTs, from August 2013 to April 2016) along an elevation profile (four sites) on the north facing the rock wall of the Vignemale peak (3,298 m a.s.l., 42°46′16″N/0°08′33″W) and temperature modeling (CryoGRID2) to determine the presence of permafrost and to analyze its evolution since the mid‐20th century. Simulations are run with various RST forcings and bedrock properties to account for forcing data uncertainty and varying degrees of rock fracturing. Results reveal that warm permafrost may have existed down to 2,600 m a.s.l. until the early 1980s and that warm permafrost is currently found at ~2,800 m a.s.l. and up to 3,000 m a.s.l. Cold (<−2°C) permafrost may exist above 3,100–3,200 m a.s.l. Systematic investigations on rock wall permafrost must be conducted to refine those results in the Pyrenees. The elevation shift in warm permafrost suggests an imminent disappearance of permafrost in the Vignemale peak.
永久冻土是比利牛斯山脉的相关组成部分，引发了广泛的地貌低温过程。尽管在过去的几十年里，比利牛斯山脉的冻土研究有所增加，但没有关于岩壁永久冻土、其存在、分布、热状况或历史演变的具体研究。这项工作结合了沿Vignemale峰（3298）北侧岩壁的高程剖面（四个地点）测量的岩石表面温度（RST，2013年8月至2016年4月） m a.s.l.，42°46′16〃N/0°08′33〃W）和温度建模（CryoGRID2），以确定永久冻土的存在并分析其自20世纪中期以来的演变。利用各种RST强迫和基岩特性进行模拟，以考虑强迫数据的不确定性和不同程度的岩石破裂。结果表明，温暖的永久冻土可能存在于2600年以前 m a.s.l.，直到20世纪80年代初，目前发现的温暖永久冻土约为2800 m a.s.l.和高达3000 m a.s.l.冷（＜−2°C）永久冻土可能存在于3100–3200以上 m a.s.l.必须对比利牛斯山脉的岩壁永久冻土进行系统的调查，以完善这些结果。温暖的永久冻土的海拔变化表明Vignemale峰的永久冻土即将消失。
{"title":"First evidence of rock wall permafrost in the Pyrenees (Vignemale peak, 3,298 m a.s.l., 42°46′16″N/0°08′33″W)","authors":"I. Rico, F. Magnin, J. López Moreno, E. Serrano, E. Alonso‐González, J. Revuelto, L. Hughes‐Allen, M. Gómez‐Lende","doi":"10.1002/ppp.2130","DOIUrl":"https://doi.org/10.1002/ppp.2130","url":null,"abstract":"Permafrost is a relevant component of the Pyrenean high mountains, triggering a wide range of geomorphological cryogenic processes. Although in the past decades there has been an increase in frozen ground studies in the Pyrenees, there are no specific studies about rock wall permafrost, its presence, distribution, thermal regime, or historical evolution. This work combines measured rock surface temperatures (RSTs, from August 2013 to April 2016) along an elevation profile (four sites) on the north facing the rock wall of the Vignemale peak (3,298 m a.s.l., 42°46′16″N/0°08′33″W) and temperature modeling (CryoGRID2) to determine the presence of permafrost and to analyze its evolution since the mid‐20th century. Simulations are run with various RST forcings and bedrock properties to account for forcing data uncertainty and varying degrees of rock fracturing. Results reveal that warm permafrost may have existed down to 2,600 m a.s.l. until the early 1980s and that warm permafrost is currently found at ~2,800 m a.s.l. and up to 3,000 m a.s.l. Cold (<−2°C) permafrost may exist above 3,100–3,200 m a.s.l. Systematic investigations on rock wall permafrost must be conducted to refine those results in the Pyrenees. The elevation shift in warm permafrost suggests an imminent disappearance of permafrost in the Vignemale peak.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"32 1","pages":"673 - 680"},"PeriodicalIF":5.0,"publicationDate":"2021-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ppp.2130","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43634985","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}
Surface energy balance (SEB) strongly influences the thermal state of permafrost, cryohydrological processes, and infrastructure stability. Road construction and snow accumulation affect the energy balance of underlying permafrost. Herein, we use an experimental road section of the Alaska Highway to develop a SEB model to quantify the surface energy components and ground surface temperature (GST) for different land cover types with varying snow regimes and properties. Simulated and measured ground temperatures are in good agreement, and our results show that the quantity of heat entering the embankment center and slope is mainly controlled by net radiation, and less by the sensible heat flux. In spring, lateral heat flux from the embankment center leads to earlier disappearance of snowpack on the embankment slope. In winter, the insulation created by the snow cover on the embankment slope reduces heat loss by a factor of three compared with the embankment center where the snow is plowed. The surface temperature offsets are 5.0°C and 7.8°C for the embankment center and slope, respectively. Furthermore, the heat flux released on the embankment slope exponentially decreases with increasing snow depth, and linearly decreases with earlier snow cover in fall and shorter snow‐covered period in spring.
{"title":"Surface energy balance of sub‐Arctic roads with varying snow regimes and properties in permafrost regions","authors":"Lin Chen, C. Voss, David H. Fortier, J. McKenzie","doi":"10.1002/ppp.2129","DOIUrl":"https://doi.org/10.1002/ppp.2129","url":null,"abstract":"Surface energy balance (SEB) strongly influences the thermal state of permafrost, cryohydrological processes, and infrastructure stability. Road construction and snow accumulation affect the energy balance of underlying permafrost. Herein, we use an experimental road section of the Alaska Highway to develop a SEB model to quantify the surface energy components and ground surface temperature (GST) for different land cover types with varying snow regimes and properties. Simulated and measured ground temperatures are in good agreement, and our results show that the quantity of heat entering the embankment center and slope is mainly controlled by net radiation, and less by the sensible heat flux. In spring, lateral heat flux from the embankment center leads to earlier disappearance of snowpack on the embankment slope. In winter, the insulation created by the snow cover on the embankment slope reduces heat loss by a factor of three compared with the embankment center where the snow is plowed. The surface temperature offsets are 5.0°C and 7.8°C for the embankment center and slope, respectively. Furthermore, the heat flux released on the embankment slope exponentially decreases with increasing snow depth, and linearly decreases with earlier snow cover in fall and shorter snow‐covered period in spring.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"32 1","pages":"681 - 701"},"PeriodicalIF":5.0,"publicationDate":"2021-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ppp.2129","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47268609","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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