{"type": "FeatureCollection", "features": [{"id": "10.1016/j.geoderma.2024.116825", "type": "Feature", "geometry": null, "properties": {"updated": "2026-10-06T16:16:20Z", "type": "Journal Article", "created": "2024-02-24", "title": "Organic carbon stabilization in temperate paddy fields and adjacent semi-natural forests along a soil age gradient", "description": "Rice paddy soils have high organic carbon (OC) storage potential, but predicting OC stocks in these soils is difficult due to the complex OC stabilization mechanisms under fluctuating redox conditions. Especially in temperate climates, these mechanisms remain understudied and comparisons to OC stocks under natural vegetation are scarce. Semi-natural forests could have similar or higher OC inputs than rice paddies, but in the latter mineralization under anoxic conditions and interactions between OC and redox-sensitive minerals (in particular Fe oxyhydroxides, hereafter referred to as Fe oxides) could promote OC stabilization. Moreover, management-induced soil redox cycling in rice paddies can interact with pre-existing pedogenetic differences of soils having different degrees of evolution. To disentangle these drivers of soil OC stocks, we focused on a soil age gradient in Northern Italy with a long (30\u00a0+\u00a0years) history of rice cultivation and remnant semi-natural forests. Irrespective of soil age, soils under semi-natural forest and paddy land-use showed comparable OC stocks. While, in topsoil, stocks of crystalline Fe and short-ranged Fe and Al oxides did not differ between land-uses, under paddy management more OC was found in the mineral-associated fraction. This hints to a stronger redox-driven OC stabilization in the paddy topsoil compared to semi-natural forest soils that might compensate for the presumed lower OC inputs under rice cropping. Despite the higher clay contents over the whole profile and more crystalline pedogenetic Fe stocks in the topsoil in older soils, OC stocks were higher in the younger soils, in particular in the 50\u201370\u00a0cm layer, where short-range ordered pedogenetic oxides were also more abundant. These patterns might be explained by differences in hydrological flows responsible for the translocation of Fe and dissolved OC to the subsoil, preferentially in the younger, coarse-textured soils. Taken together, these results indicate the importance of the complex interplay between redox-cycling affected by paddy-management and soil-age related hydrological properties.", "keywords": ["2. Zero hunger", "Science", "Q", "Soil Science", "Soil carbon storage", "04 agricultural and veterinary sciences", "15. Life on land", "Markvetenskap", "01 natural sciences", "Particulate organic carbon", "Fe oxyhydroxides", "0401 agriculture", " forestry", " and fisheries", "Rice paddy soil", "Mineral associated organic carbon", "0105 earth and related environmental sciences"]}, "links": [{"href": "https://iris.unito.it/bitstream/2318/1963515/1/Geoderma_443_116825.pdf"}, {"href": "https://doi.org/10.1016/j.geoderma.2024.116825"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Geoderma", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1016/j.geoderma.2024.116825", "name": "item", "description": "10.1016/j.geoderma.2024.116825", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1016/j.geoderma.2024.116825"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2024-03-01T00:00:00Z"}}, {"id": "10.1029/2019jg005511", "type": "Feature", "geometry": null, "properties": {"updated": "2026-10-06T16:17:12Z", "type": "Journal Article", "created": "2020-01-29", "title": "Particulate Organic Matter Dynamics in a Permafrost Headwater Stream and the Kolyma River Mainstem", "description": "Abstract

Ongoing rapid arctic warming leads to extensive permafrost thaw, which in turn increases the hydrologic connectivity of the landscape by opening up subsurface flow paths. Suspended particulate organic matter (POM) has proven useful to trace permafrost thaw signals in arctic rivers, which may experience higher organic matter loads in the future due to expansion and increasing intensity of thaw processes such as thermokarst and river bank erosion. Here we focus on the Kolyma River watershed in Northeast Siberia, the world's largest watershed entirely underlain by continuous permafrost. To evaluate and characterize the present\uffe2\uff80\uff90day fluvial release of POM from permafrost thaw, we collected water samples every 4\uffe2\uff80\uff937 days during the 4\uffe2\uff80\uff90month open water season in 2013 and 2015 from the lower Kolyma River mainstem and from a small nearby headwater stream (Y3) draining an area completely underlain by Yedoma permafrost (Pleistocene ice\uffe2\uff80\uff90 and organic\uffe2\uff80\uff90rich deposits). Concentrations of particulate organic carbon generally followed the hydrograph with the highest concentrations during the spring flood in late May/early June. For the Kolyma River, concentrations of dissolved organic carbon showed a similar behavior, in contrast to the headwater stream, where dissolved organic carbon values were generally higher and particulate organic carbon concentrations lower than for Kolyma. Carbon isotope analysis (\uffce\uffb413C, \uffce\uff9414C) suggested Kolyma\uffe2\uff80\uff90POM to stem from both contemporary and older permafrost sources, while Y3\uffe2\uff80\uff90POM was more strongly influenced by in\uffe2\uff80\uff90stream production and recent vegetation. Lipid biomarker concentrations (high\uffe2\uff80\uff90molecular\uffe2\uff80\uff90weight n\uffe2\uff80\uff90alkanoic acids and n\uffe2\uff80\uff90alkanes) did not display clear seasonal patterns, yet implied Y3\uffe2\uff80\uff90POM to be more degraded than Kolyma\uffe2\uff80\uff90POM.On\uffe2\uff80\uff90going shrinkage of Greenland's icecap, permafrost thaw, and changes in precipitation are exposing its landscapes to erosion and remobilization of ancient organic carbon (OC) held in soils and sedimentary rocks. The fate of this OC and potential feedbacks to climate are still unclear. Here, we show that the glacial Zackenberg river (Northeastern Greenland) exports aged particulate OC (POC, uncalibrated radiocarbon ages of \uffe2\uff88\uffbc4,000\uffc2\uffa0years). Many of the smaller periglacial streams affected by abrupt permafrost thaw transport substantially older POC (up to 32,000\uffc2\uffa0years), especially with enhanced discharge following intense precipitation. Mineralogical analysis, and density and size fractionation of soils and both glacial and nonglacial river sediments reveal that OC is largely associated with phyllosilicate minerals, suggesting stabilization against microbial processing. Enhanced export of ancient, mineral\uffe2\uff80\uff90associated OC as a consequence of summer rainfall may accelerate translocation of OC from terrestrial to marine environments, but could have limited consequences for climate.Collapse of permafrost coasts delivers large quantities of particulate organic carbon (POC) to Arctic coastal areas. With rapidly changing environmental conditions, sediment and organic carbon (OC) mobilization and transport pathways are also changing. Here, we assess the sources and sinks of POC in the highly dynamic nearshore zone of Herschel Island\uffe2\uff80\uff90Qikiqtaruk (Yukon, Canada). Our results show that POC concentrations sharply decrease, from 15.9 to 0.3\uffc2\uffa0mg\uffc2\uffa0L\uffe2\uff88\uff921, within the first 100\uffe2\uff80\uff93300\uffc2\uffa0m offshore. Simultaneously, radiocarbon ages of POC drop from 16,400 to 3,600 14C years, indicating rapid settling of old permafrost POC to underlying sediments. This suggests that permafrost OC is, apart from a very narrow resuspension zone (<5\uffc2\uffa0m water depth), predominantly deposited in nearshore sediments. While long\uffe2\uff80\uff90term storage of permafrost OC in marine sediments potentially limits biodegradation and its subsequent release as greenhouse gas, resuspension of fine\uffe2\uff80\uff90grained, OC\uffe2\uff80\uff90rich sediments in the nearshore zone potentially enhances OC turnover.The magnitude of future emissions of greenhouse gases from the northern permafrost region depends crucially on the mineralization of soil organic carbon (SOC) that has accumulated over millennia in these perennially frozen soils. Many recent studies have used radiocarbon (14C) to quantify the release of this \uffe2\uff80\uff9cold\uffe2\uff80\uff9d SOC as CO2 or CH4 to the atmosphere or as dissolved and particulate organic carbon (DOC and POC) to surface waters. We compiled ~1,900 14C measurements from 51 sites in the northern permafrost region to assess the vulnerability of thawing SOC in tundra, forest, peatland, lake, and river ecosystems. We found that growing season soil 14C\uffe2\uff80\uff90CO2 emissions generally had a modern (post\uffe2\uff80\uff901950s) signature, but that well\uffe2\uff80\uff90drained, oxic soils had increased CO2 emissions derived from older sources following recent thaw. The age of CO2 and CH4 emitted from lakes depended primarily on the age and quantity of SOC in sediments and on the mode of emission, and indicated substantial losses of previously frozen SOC from actively expanding thermokarst lakes. Increased fluvial export of aged DOC and POC occurred from sites where permafrost thaw caused soil thermal erosion. There was limited evidence supporting release of previously frozen SOC as CO2, CH4, and DOC from thawing peatlands with anoxic soils. This synthesis thus suggests widespread but not universal release of permafrost SOC following thaw. We show that different definitions of \uffe2\uff80\uff9cold\uffe2\uff80\uff9d sources among studies hamper the comparison of vulnerability of permafrost SOC across ecosystems and disturbances. We also highlight opportunities for future 14C studies in the permafrost region.Growing interest in the potential for agricultural soils to provide a sink for atmospheric C has prompted studies of effects of management on soil organic carbon (SOC) sequestration. We analyzed the impact on SOC of four N fertilization rates (0\uffe2\uff80\uff93270 kg N ha\uffe2\uff88\uff921) and four cropping systems: continuous corn (CC) (Zea mays L.); corn\uffe2\uff80\uff93soybean [Glycine max (L.) Merr.] (CS); corn\uffe2\uff80\uff93corn\uffe2\uff80\uff93oat\uffe2\uff80\uff93alfalfa (oat, Avena sativa L.; alfalfa, Medicago sativa L.) (CCOA), and corn\uffe2\uff80\uff93oat\uffe2\uff80\uff93alfalfa\uffe2\uff80\uff93alfalfa (COAA). Soils were sampled in 2002, Years 23 and 48 of the experiments located in northeast and north\uffe2\uff80\uff90central Iowa, respectively. The experiments were conducted using a replicated split\uffe2\uff80\uff90plot design under conventional tillage. A native prairie was sampled to provide a reference (for one site only). Cropping systems that contained alfalfa had the highest SOC stocks, whereas the CS system generally had the lowest SOC stocks. Concentrations of SOC increased significantly between 1990 and 2002 in only two of the nine systems for which historical data were available, the fertilized CC and COAA systems at one site. Soil quality indices such as particulate organic carbon (POC) were influenced by cropping system, with CS < CC < CCOA. In the native prairie, SOC, POC, and resistant C concentrations were 2.8, 2.6, and 3.9 times, respectively, the highest values in cropped soil, indicating that cultivated soils had not recovered to precultivation conditions. Although corn yields increased with N additions, N fertilization increased SOC stocks only in the CC system at one site. Considering the C cost for N fertilizer production, N fertilization generally had a net negative effect on C sequestration.

", "keywords": ["corn\u2013soybean MAP", "2. Zero hunger", "particulate organic carbon SIC", "soil organic carbon SOM", "soil organic matter TN", "corn\u2013corn\u2013oat\u2013alfalfa CE", "corn\u2013oat\u2013alfalfa\u2013alfalfa CS", "Natural Resources Management and Policy", "Carlo-Erba COAA", "Soil Science", "Walkley-Black", "soil inorganic carbon SOC", "04 agricultural and veterinary sciences", "15. Life on land", "CC", "630", "6. Clean water", "\u03c1b", "mean annual precipitation PMC", "total nitrogen WB", "Agronomy and Crop Sciences", "continuous corn CCOA", "0401 agriculture", " forestry", " and fisheries", "potential mineralization of carbon POC"]}, "links": [{"href": "https://doi.org/10.2136/sssaj2005.0413"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Soil%20Science%20Society%20of%20America%20Journal", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.2136/sssaj2005.0413", "name": "item", "description": "10.2136/sssaj2005.0413", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.2136/sssaj2005.0413"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2005-03-01T00:00:00Z"}}, {"id": "10.5194/bg-22-601-2025", "type": "Feature", "geometry": null, "properties": {"updated": "2026-10-06T16:20:12Z", "type": "Journal Article", "created": "2025-01-31", "title": "Contrasting seasonal patterns in particle aggregation and dissolved organic matter transformation in a sub-Arctic fjord", "description": "

Abstract. Particulate (POM) and dissolved (DOM) organic matter in the ocean are important components of the Earth's biogeochemical cycle. The two are in a constant state of dynamic change as a result of physical and biochemical processes; however, they are mostly treated as two distinct entities, separated operationally by a filter. We studied the seasonal transition of DOM and POM pools and their drivers in a sub-Arctic fjord by means of monthly environmental sampling and by performing experiments at selected time points. For the experiments, surface water (5\u2009m) was either pre-filtered through a GF/F filter (0.7\u2009\u00b5m) or left unfiltered, followed by 36\u2009h incubations. Before and after incubation, samples were collected for dissolved and particulate organic carbon concentrations (DOC, POC), extracellular polymeric substances (EPSs), microbial community (flow cytometry), and molecular composition of DOM (high-performance liquid chromatography coupled to high-resolution mass spectrometry \u2013 HPLC-HRMS). During the biologically productive period, when environmental POC concentrations were high (April, June, September), the filtered water showed an increase in POC concentrations. While POC concentrations increased in September, DOM lability decreased based on changes in the average hydrogen saturation and aromaticity of DOM molecules. In contrast, during the winter period (December and February), when environmental POC concentrations were low, lower concentrations of POC were measured at the end of the experiments compared to at the start. The change in POC concentrations was significantly different between the biologically productive period and the winter period (t test; p<0.05). Simultaneously, the DOM pool became more labile during the incubation period, as indicated by changes in the average hydrogen saturation, aromaticity, and oxygen saturation, with implications for carbon cycling. The change in POC was not directly associated with an antagonistic change in DOC concentrations, highlighting the complexity of organic matter transformations, making the dynamics between POC and DOC difficult to quantify. However, in both periods, bacterial activity and EPS concentrations increased throughout the incubations, showing that bacterial degradation and physical DOM aggregation drive the transformations of POM and DOM in concert but at varying degrees under different environmental conditions.

", "keywords": ["particulate organic carbon", "seasonal variation", "QE1-996.5", "Ecology", "saturation", "aggregation", "surface water", "fjord", "Geology", "biogeochemical cycle", "Milj\u00f6vetenskap", "dissolved organic carbon", "microbial activity", "environmental conditions", "Life", "QH501-531", "microbial community", "Environmental Sciences", "QH540-549.5"], "contacts": [{"organization": "Maria G. Digernes, Yasemin V. Bodur, Mart\u00ed Amargant-Arum\u00ed, Oliver M\u00fcller, Jeffrey A. Hawkes, Stephen G. Kohler, Ulrike Dietrich, Marit Reigstad, Maria L. Paulsen,", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.5194/bg-22-601-2025"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Biogeosciences", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.5194/bg-22-601-2025", "name": "item", "description": "10.5194/bg-22-601-2025", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.5194/bg-22-601-2025"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2025-01-31T00:00:00Z"}}, {"id": "20.500.11850/403804", "type": "Feature", "geometry": null, "properties": {"updated": "2026-10-06T16:22:49Z", "type": "Journal Article", "created": "2020-01-29", "title": "Particulate Organic Matter Dynamics in a Permafrost Headwater Stream and the Kolyma River Mainstem", "description": "Abstract

Ongoing rapid arctic warming leads to extensive permafrost thaw, which in turn increases the hydrologic connectivity of the landscape by opening up subsurface flow paths. Suspended particulate organic matter (POM) has proven useful to trace permafrost thaw signals in arctic rivers, which may experience higher organic matter loads in the future due to expansion and increasing intensity of thaw processes such as thermokarst and river bank erosion. Here we focus on the Kolyma River watershed in Northeast Siberia, the world's largest watershed entirely underlain by continuous permafrost. To evaluate and characterize the present\uffe2\uff80\uff90day fluvial release of POM from permafrost thaw, we collected water samples every 4\uffe2\uff80\uff937 days during the 4\uffe2\uff80\uff90month open water season in 2013 and 2015 from the lower Kolyma River mainstem and from a small nearby headwater stream (Y3) draining an area completely underlain by Yedoma permafrost (Pleistocene ice\uffe2\uff80\uff90 and organic\uffe2\uff80\uff90rich deposits). Concentrations of particulate organic carbon generally followed the hydrograph with the highest concentrations during the spring flood in late May/early June. For the Kolyma River, concentrations of dissolved organic carbon showed a similar behavior, in contrast to the headwater stream, where dissolved organic carbon values were generally higher and particulate organic carbon concentrations lower than for Kolyma. Carbon isotope analysis (\uffce\uffb413C, \uffce\uff9414C) suggested Kolyma\uffe2\uff80\uff90POM to stem from both contemporary and older permafrost sources, while Y3\uffe2\uff80\uff90POM was more strongly influenced by in\uffe2\uff80\uff90stream production and recent vegetation. Lipid biomarker concentrations (high\uffe2\uff80\uff90molecular\uffe2\uff80\uff90weight n\uffe2\uff80\uff90alkanoic acids and n\uffe2\uff80\uff90alkanes) did not display clear seasonal patterns, yet implied Y3\uffe2\uff80\uff90POM to be more degraded than Kolyma\uffe2\uff80\uff90POM.14C measurements of CO2, CH4, DOC and POC mostly from the northern permafrost region. Some other studies are included from sites not underlained by permafrost. The dataset focuses on 14C measurements of gaseous soil emissions and waterborne ecosystem C fluxes but the database also included C forms belowground, such as soil gases and pore water DOC.", "keywords": ["13. Climate action", "15. Life on land", "radiocarbon", " permafrost", " carbon dioxide", " methane", " dissolved organic carbon", " particulate organic carbon", " DOC", " POC", " thermokarst", " thaw"], "contacts": [{"organization": "Estop-Aragon\u00e9s, Cristian", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.5281/zenodo.3832031"}, {"rel": "self", "type": "application/geo+json", "title": "10.5281/zenodo.3832031", "name": "item", "description": "10.5281/zenodo.3832031", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.5281/zenodo.3832031"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2020-05-18T00:00:00Z"}}, {"id": "10.5281/zenodo.5652048", "type": "Feature", "geometry": null, "properties": {"updated": "2026-10-06T16:21:25Z", "type": "Dataset", "title": "Transport of Particulate Organic Carbon in The Huanghe: Insights from Lateral And Vertical Heterogeneity in a River Cross-section", "description": "The Huanghe (Yellow River), one of the largest turbid river systems in the world, has long been recognized as a major contributor of suspended particulate matter (SPM) to the ocean. However, over the last few decades, the SPM export flux of the Huanghe has decreased over 90% due to the high management, impacting the global export of particulate organic carbon (POC). To better constrain sources and modes of transport of POC beyond the previously investigated transportation of POC near the channel surface, SPM samples were for the first time collected over a whole channel cross-section in the lower Huanghe. Riverine SPM samples were analyzed for particle size and major element contents, as well as for POC content and dual carbon isotopes (13C and 14C). The results show clear vertical and lateral heterogeneity of SPM physical and chemical characteristics within the river cross section, with for example finer SPM carrying more POC with higher 14C activity near the surface and the right bank. Notably, we discuss how bank erosion in the alluvial plain is likely to generate lateral heterogeneity in POC composition. The Huanghe POC is millennial-aged (4,020 \u00b1 500 radiocarbon years), dominated by organic carbon (OC) from the biosphere, while the lithospheric fraction reaches up to ca. 33%. The mobilization of aged and refractory OC from deeper soil horizons of the loess-paleosol sequence through erosion in the Chinese Loess Plateau is an important mechanism contributing to fluvial POC in the Huanghe drainage basin. The involvement of this OC fraction has significance for the regional and global carbon cycles, especially regarding its final fate in the estuary. Altogether, this study sheds light on the mechanism of fluvial transfer of POC and corresponding impacts on the carbon cycle in large river systems strongly perturbed by anthropogenic activities.", "keywords": ["particulate organic carbon", "13. Climate action", "Huanghe", "bank erosion", "radiocarbon", "depth profile sampling", "14. Life underwater", "15. Life on land", "6. Clean water"], "contacts": [{"organization": "Yutian, Ke, Calmels Damien, Bouchez Julien, Massault Marc, Chetelat Benjamin, Noret Aur\u00e9lie, Hongming, Cai, Jiubin, Chen, Gaillardet J\u00e9r\u00f4me, Quantin C\u00e9cile,", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.5281/zenodo.5652048"}, {"rel": "self", "type": "application/geo+json", "title": "10.5281/zenodo.5652048", "name": "item", "description": "10.5281/zenodo.5652048", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.5281/zenodo.5652048"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2022-06-06T00:00:00Z"}}, {"id": "11250/3212345", "type": "Feature", "geometry": null, "properties": {"updated": "2026-10-06T16:22:30Z", "type": "Journal Article", "created": "2025-01-31", "title": "Contrasting seasonal patterns in particle aggregation and dissolved organic matter transformation in a sub-Arctic fjord", "description": "

Abstract. Particulate (POM) and dissolved (DOM) organic matter in the ocean are important components of the Earth's biogeochemical cycle. The two are in a constant state of dynamic change as a result of physical and biochemical processes; however, they are mostly treated as two distinct entities, separated operationally by a filter. We studied the seasonal transition of DOM and POM pools and their drivers in a sub-Arctic fjord by means of monthly environmental sampling and by performing experiments at selected time points. For the experiments, surface water (5\u2009m) was either pre-filtered through a GF/F filter (0.7\u2009\u00b5m) or left unfiltered, followed by 36\u2009h incubations. Before and after incubation, samples were collected for dissolved and particulate organic carbon concentrations (DOC, POC), extracellular polymeric substances (EPSs), microbial community (flow cytometry), and molecular composition of DOM (high-performance liquid chromatography coupled to high-resolution mass spectrometry \u2013 HPLC-HRMS). During the biologically productive period, when environmental POC concentrations were high (April, June, September), the filtered water showed an increase in POC concentrations. While POC concentrations increased in September, DOM lability decreased based on changes in the average hydrogen saturation and aromaticity of DOM molecules. In contrast, during the winter period (December and February), when environmental POC concentrations were low, lower concentrations of POC were measured at the end of the experiments compared to at the start. The change in POC concentrations was significantly different between the biologically productive period and the winter period (t test; p<0.05). Simultaneously, the DOM pool became more labile during the incubation period, as indicated by changes in the average hydrogen saturation, aromaticity, and oxygen saturation, with implications for carbon cycling. The change in POC was not directly associated with an antagonistic change in DOC concentrations, highlighting the complexity of organic matter transformations, making the dynamics between POC and DOC difficult to quantify. However, in both periods, bacterial activity and EPS concentrations increased throughout the incubations, showing that bacterial degradation and physical DOM aggregation drive the transformations of POM and DOM in concert but at varying degrees under different environmental conditions.

", "keywords": ["particulate organic carbon", "seasonal variation", "QE1-996.5", "Ecology", "saturation", "aggregation", "surface water", "fjord", "Geology", "biogeochemical cycle", "Milj\u00f6vetenskap", "dissolved organic carbon", "microbial activity", "environmental conditions", "Life", "QH501-531", "microbial community", "Environmental Sciences", "QH540-549.5"]}, "links": [{"href": "https://doi.org/11250/3212345"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Biogeosciences", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "11250/3212345", "name": "item", "description": "11250/3212345", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/11250/3212345"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2025-01-31T00:00:00Z"}}, {"id": "1871.1/a9511e83-fead-49ba-9642-c0295015d109", "type": "Feature", "geometry": null, "properties": {"updated": "2026-10-06T16:22:41Z", "type": "Report", "title": "Particulate organic matter dynamics and degradation in Arctic fluvial systems", "description": "The Arctic is warming two to four times the rate of global average. The increase in air temperatures causes permafrost (i.e., perennially frozen ground) to thaw and release previously frozen organic carbon (OC) to the contemporary carbon cycle. Permafrost stores large amounts of organic carbon (~1300 \u00b1 200 Pg), which equals up to half of the belowground OC globally. Re-mineralization of the released permafrost OC can add greenhouse gases (CO2, CH4) to the atmosphere enhancing climate warming. Gradual permafrost thaw happens when the active layer (i.e., the topmost layer of permafrost that thaws during summer months) deepens due to climate warming releasing largely dissolved organic carbon (DOC). On the contrary, in permafrost regions with high ground ice-content, permafrost thaw happens abruptly (i.e., thermokarst) as landscapes subside or collapse due to melting of ice. Abrupt permafrost thaw releases dominantly particulate organic carbon (POC). While degradation of DOC has been extensively studied in Arctic fluvial systems, degradation of POC is still poorly characterized. In this study, we investigate POC composition and degradation in two different areas: i) in the thaw streams draining abrupt permafrost thaw features, retrogressive thaw slumps (RTS), on the Canadian Peel Plateau, and ii) in the Kolyma River, which is one of the major Arctic rivers draining to the Arctic Ocean. We also study carbon dynamics and water chemistry parameters in lower order streams within the Kolyma watershed in two hydrologically distinct seasons: spring freshet and summer. We use macro(molecular) methods, pyrolysis \u2013 gas chromatography mass spectrometry and lipid biomarkers (n-alkanes, n-alkanoic acids), to analyse POC composition and degradation status. For further compositional analysis, we use carbon isotopes (\u03b413C, \u039414C). Additionally, we employ spatial data analysis and statistical modelling to characterize the watersheds and POC sources. Our results indicate that POC composition is seasonally dependent, and it defines biodegradability of POC. On the Peel Plateau, POC consists largely of aromatic moieties and includes petrogenic carbon that are not easily degradable. By contrast, Kolyma River POC degrades relatively fast during summer, when it is mostly of autochthonous sources. However, freshet POC, dominated by allochthonous POC, is not readily degradable. During freshet, DOC is susceptible to adsorption to particles and/or flocculation, potentially attenuating its climate impact. The lower order streams within the Kolyma River watershed react fast to increase in air temperatures during spring freshet with increased surface water temperatures and depletion in \u03b413C-POC, suggesting early onset of primary production. Changes in water temperature and \u03b413C-POC were not as pronounced in the Kolyma River. These results suggest that lower order streams may start primary production and POC degradation earlier in the season than the larger ones and thus, start emitting greenhouse gases earlier. The degraded POC is mostly autochthonous, and more studies are needed to investigate whether degradation of autochthonous POC may stimulate degradation of allochthonous or permafrost POC. These results highlight the heterogeneity of the Arctic fluvial networks and the differences in their response to climate warming.", "keywords": ["Organische koolstof", "Afbraak", "Organische koolstof in suspensie", "Permafrost", "Flocculation", "Kolyma Rivier", "Flocculatie", "Klimaatverandering", "Particulate organic carbon", "Adsorptie", "Degradation", "Kolyma River", "Arctic", "Peel Plateau", "Climate change", "Adsorption", "Arctisch", "Organic carbon"], "contacts": [{"organization": "Keskitalo, Kirsi Helena", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/1871.1/a9511e83-fead-49ba-9642-c0295015d109"}, {"rel": "self", "type": "application/geo+json", "title": "1871.1/a9511e83-fead-49ba-9642-c0295015d109", "name": "item", "description": "1871.1/a9511e83-fead-49ba-9642-c0295015d109", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/1871.1/a9511e83-fead-49ba-9642-c0295015d109"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2022-11-09T00:00:00Z"}}, {"id": "1983/b92f4977-b482-4b57-9710-09413462ccde", "type": "Feature", "geometry": null, "properties": {"updated": "2026-10-06T16:22:45Z", "type": "Journal Article", "created": "2020-09-02", "title": "Assessing the Potential for Mobilization of Old Soil Carbon After Permafrost Thaw: A Synthesis of 14C Measurements From the Northern Permafrost Region", "description": "Abstract

The magnitude of future emissions of greenhouse gases from the northern permafrost region depends crucially on the mineralization of soil organic carbon (SOC) that has accumulated over millennia in these perennially frozen soils. Many recent studies have used radiocarbon (14C) to quantify the release of this \uffe2\uff80\uff9cold\uffe2\uff80\uff9d SOC as CO2 or CH4 to the atmosphere or as dissolved and particulate organic carbon (DOC and POC) to surface waters. We compiled ~1,900 14C measurements from 51 sites in the northern permafrost region to assess the vulnerability of thawing SOC in tundra, forest, peatland, lake, and river ecosystems. We found that growing season soil 14C\uffe2\uff80\uff90CO2 emissions generally had a modern (post\uffe2\uff80\uff901950s) signature, but that well\uffe2\uff80\uff90drained, oxic soils had increased CO2 emissions derived from older sources following recent thaw. The age of CO2 and CH4 emitted from lakes depended primarily on the age and quantity of SOC in sediments and on the mode of emission, and indicated substantial losses of previously frozen SOC from actively expanding thermokarst lakes. Increased fluvial export of aged DOC and POC occurred from sites where permafrost thaw caused soil thermal erosion. There was limited evidence supporting release of previously frozen SOC as CO2, CH4, and DOC from thawing peatlands with anoxic soils. This synthesis thus suggests widespread but not universal release of permafrost SOC following thaw. We show that different definitions of \uffe2\uff80\uff9cold\uffe2\uff80\uff9d sources among studies hamper the comparison of vulnerability of permafrost SOC across ecosystems and disturbances. We also highlight opportunities for future 14C studies in the permafrost region.Collapse of permafrost coasts delivers large quantities of particulate organic carbon (POC) to Arctic coastal areas. With rapidly changing environmental conditions, sediment and organic carbon (OC) mobilization and transport pathways are also changing. Here, we assess the sources and sinks of POC in the highly dynamic nearshore zone of Herschel Island\uffe2\uff80\uff90Qikiqtaruk (Yukon, Canada). Our results show that POC concentrations sharply decrease, from 15.9 to 0.3\uffc2\uffa0mg\uffc2\uffa0L\uffe2\uff88\uff921, within the first 100\uffe2\uff80\uff93300\uffc2\uffa0m offshore. Simultaneously, radiocarbon ages of POC drop from 16,400 to 3,600 14C years, indicating rapid settling of old permafrost POC to underlying sediments. This suggests that permafrost OC is, apart from a very narrow resuspension zone (<5\uffc2\uffa0m water depth), predominantly deposited in nearshore sediments. While long\uffe2\uff80\uff90term storage of permafrost OC in marine sediments potentially limits biodegradation and its subsequent release as greenhouse gas, resuspension of fine\uffe2\uff80\uff90grained, OC\uffe2\uff80\uff90rich sediments in the nearshore zone potentially enhances OC turnover.On\uffe2\uff80\uff90going shrinkage of Greenland's icecap, permafrost thaw, and changes in precipitation are exposing its landscapes to erosion and remobilization of ancient organic carbon (OC) held in soils and sedimentary rocks. The fate of this OC and potential feedbacks to climate are still unclear. Here, we show that the glacial Zackenberg river (Northeastern Greenland) exports aged particulate OC (POC, uncalibrated radiocarbon ages of \uffe2\uff88\uffbc4,000\uffc2\uffa0years). Many of the smaller periglacial streams affected by abrupt permafrost thaw transport substantially older POC (up to 32,000\uffc2\uffa0years), especially with enhanced discharge following intense precipitation. Mineralogical analysis, and density and size fractionation of soils and both glacial and nonglacial river sediments reveal that OC is largely associated with phyllosilicate minerals, suggesting stabilization against microbial processing. Enhanced export of ancient, mineral\uffe2\uff80\uff90associated OC as a consequence of summer rainfall may accelerate translocation of OC from terrestrial to marine environments, but could have limited consequences for climate.