Biogeochemistry最新文献

{"title":"Sphagnan in Sphagnum-dominated peatlands: bioavailability and effects on organic matter stabilization","authors":"Lauren Bryan,&nbsp;Rachel Shaw,&nbsp;Erik Schoonover,&nbsp;Alexis Koehl,&nbsp;Suzanne DeVries-Zimmerman,&nbsp;Michael Philben","doi":"10.1007/s10533-024-01134-2","DOIUrl":"10.1007/s10533-024-01134-2","url":null,"abstract":"<div><p>The unique pectin-like carbohydrate “sphagnan” has been shown to protect organic matter from microbial decomposition in <i>Sphagnum</i>-dominated peatlands. However, the bioavailability of sphagnan has not been evaluated, and it is not known if it persists or continues to affect decomposition processes over the long timescales of peat formation. To address this, we assessed the connection between sphagnan content and organic matter decomposition rates in a temperate peatland near Fennville, MI, USA. We compared the effects of sphagnan over two timescales: (1) a short-term litter incubation assay using mosses from different peatland microtopographies; and (2) oxic and anoxic incubation assays of peat collected from multiple depths within the peat profile, reflecting a natural long-term decomposition continuum. On both timescales, we hypothesized that higher sphagnan content would be associated with lower decomposition rates, and that sphagnan would be selectively preserved compared to bulk C and other carbohydrates. The litter decomposition experiment supported both hypotheses, as higher sphagnan content was associated with lower mass loss, and sphagnan content increased due to selective preservation. In the peat, we observed weak but significant correlations between the relative abundance of sphagnan (as a fraction of total non-cellulosic sugars) and both aerobic and anaerobic respiration rates. This relationship was stronger in cores collected from hollow microtopographies than those from hummocks. However, there was not a significant relationship between respiration rates and the total (C-normalized) sphagnan content. Sphagnan content increased with depth in the peat profile, indicating selective preservation compared to bulk C. Additionally, we observed the accumulation of non-cellulosic glucose in the deep peat, likely derived from microbial exopolysaccharides. Together, these results indicate that sphagnan persists in the catotelm and continues to contribute to the long-term stabilization of organic matter in <i>Sphagnum</i>-rich peatlands, although the weak relationship with respiration indicates that its influence is relatively minor.</p></div>","PeriodicalId":8901,"journal":{"name":"Biogeochemistry","volume":"167 5","pages":"665 - 680"},"PeriodicalIF":3.9,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10533-024-01134-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140541336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microbial abundances and carbon use under ambient temperature or experimental warming in a southern boreal peatland","authors":"Mark Felice,&nbsp;Cameron M. Blake,&nbsp;Stephen Sebestyen,&nbsp;Jessica L. M. Gutknecht","doi":"10.1007/s10533-024-01129-z","DOIUrl":"10.1007/s10533-024-01129-z","url":null,"abstract":"<div><p>Organic peat soils occupy relatively little of the global land surface area but store vast amounts of soil carbon in northern latitudes where climate is warming at a rapid pace. Warming may result in strong positive feedbacks of carbon loss and global climate change driven by microbial processes if warming alters the balance between primary productivity and decomposition. To elucidate effects of warming on the microbial communities mediating peat carbon dynamics, we explored the abundance of broad microbial groups and their source of carbon (i.e. old carbon versus more recently fixed photosynthate) using microbial lipid analysis (δ¹³C PLFA) of peat samples under ambient temperatures and before/after initiation of experimental peat warming (+ 2.25, + 4.5, + 6.75, and + 9 °C). This analysis occurred over a profile to 2 m depth in an undrained, ombrotrophic peat bog in northern Minnesota. We found that the total microbial biomass and individual indicator lipid abundances were stratified by depth and strongly correlated to temperature under ambient conditions. However, under experimental warming, statistically significant effects of temperature on the microbial community were sporadic and inconsistent. For example, 3 months after experimental warming the relative abundance of Gram-negative bacterial indicators across depth combined and &gt; 50 cm depth and Gram-positive bacterial indicators at 20–50 cm depth showed significant positive relationships to temperature. At that same timepoint, however, the relative abundance of Actinobacterial indicators across depth showed a significant negative relationship to temperature. After 10 months of experimental warming, the relative abundance of fungal biomarkers was positively related to temperature in all depths combined, and the absolute abundance of anaerobic bacteria declined with increasing temperature in the 20–50 cm depth interval. The lack of observed response in the broader microbial community may suggest that at least initially, microbial community structure with peat depth in these peatlands is driven more by bulk density and soil water content than temperature. Alternatively, the lack of broad microbial community response may simply represent a lag period, with more change to come in the future. The long-term trajectory of microbial response to warming in this ecosystem then could either be direct, after this initial lag time, or indirect through other physical or biogeochemical changes in the peat profile. These initial results provide an important baseline against which to measure long-term microbial community and carbon-cycling responses to warming and elevated CO₂.</p></div>","PeriodicalId":8901,"journal":{"name":"Biogeochemistry","volume":"167 5","pages":"631 - 650"},"PeriodicalIF":3.9,"publicationDate":"2024-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10533-024-01129-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140291548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Inconsistent recovery of nitrogen cycling after feral ungulate removal across three tropical island ecosystems","authors":"Fiona M. Soper,&nbsp;Kimberlee S. Sparks,&nbsp;Rebecca J. Cole,&nbsp;Christian P. Giardina,&nbsp;Creighton M. Litton,&nbsp;Jed P. Sparks","doi":"10.1007/s10533-024-01120-8","DOIUrl":"10.1007/s10533-024-01120-8","url":null,"abstract":"<div><p>Non-native ungulates (sheep, goats, and pigs) have significant negative impacts on ecosystem biodiversity, structure, and biogeochemical function throughout the Pacific Islands. Elevated nitrogen (N) availability associated with ungulate disturbance has been shown to promote the success of resource-exploitive invasive plants. While ungulate removal is a common restoration intervention, evaluations of its efficacy typically focus on vegetation responses, rather than underlying nutrient cycling. We used multiple chronosequences of ungulate exclusion (10–24 years duration) in three Hawaiian ecosystems (montane wet forest, dry forest, and dry shrubland) to determine N cycle recovery by characterizing gross mineralization and nitrification, soil inorganic N concentrations and leaching, N₂O emissions, and plant tissue δ¹⁵N. Ungulate removal led to a 1–2 ‰ decline in foliar δ¹⁵N in most species, consistent with a long-term decrease in N fractionation via ecosystem N losses, or a shift in the relative turnover of N forms. This interpretation was supported by significant (dry forest) or trending (wet forest) increases in mineralization and decreases in nitrification, but conflicts with lack of observed change in inorganic N pool sizes or gaseous losses, and increased leaching in the dry forest. While results could indicate that ungulate invasions do not strongly impact N cycling in the first place (no uninvaded control sites exist in Hawai’i to test this hypothesis), this would be inconsistent with observations from other sites globally. Instead, impacts may be spatially patchy across the landscape, or ungulate invasions (possibly in combination with other disturbances) may have permanently shifted biogeochemical function or decoupled elemental cycles. We conclude that eliminating ungulate disturbance alone may not achieve restoration goals related to N cycling within the timeframe examined here.</p></div>","PeriodicalId":8901,"journal":{"name":"Biogeochemistry","volume":"167 5","pages":"651 - 663"},"PeriodicalIF":3.9,"publicationDate":"2024-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10533-024-01120-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140291624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Soil nitrogen cycling in forests invaded by the shrub Rosa multiflora: importance of soil moisture and invasion density","authors":"Eric R. Moore,&nbsp;Richard V. Pouyat,&nbsp;Tara L. E. Trammell","doi":"10.1007/s10533-024-01133-3","DOIUrl":"10.1007/s10533-024-01133-3","url":null,"abstract":"<div><p>Invasive plants often alter ecosystem function and processes, especially soil N cycling. In eastern United States forests, the shrub <i>Rosa multiflora</i> (“rose”) is a dominant invader, yet potential effects on N cycling are poorly understood. Moreover, invasive plant management can impact soil N cycling by decreasing plant N uptake and disturbing the soil. The objectives of this study were to evaluate N cycling along a gradient of rose invasion (observational) and investigate potential changes to N cycling (manipulative) under four different management strategies: (1) do nothing (the control), (2) invasive plant removal, (3) removal followed by native seed mix addition, (4) removal, native seed mix, and chipped rose stem addition. We selected three forest sites experiencing a Low, Medium, or High amount of shrub invasion, and measured N cycling in the early (June) and late (September) growing seasons. We found N was immobilized in June and mineralized in September. One year after experimental management, removal alone had no effect on N cycling compared to control plots, but addition of native seed mix and chipped stems reduced early-season nitrification in our Medium invasion site. Our findings suggest that rose invasion may increase N cycling rates when soils are dry, which may occur more frequently with future climate change. In addition, N cycling responds differentially to management in the year following invasive plant removal, but most noticeably under moderate rose invasion.</p></div>","PeriodicalId":8901,"journal":{"name":"Biogeochemistry","volume":"167 3","pages":"301 - 319"},"PeriodicalIF":3.9,"publicationDate":"2024-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10533-024-01133-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140196114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unraveling microbial processes involved in carbon and nitrogen cycling and greenhouse gas emissions in rewetted peatlands by molecular biology","authors":"Emilie Gios,&nbsp;Erik Verbruggen,&nbsp;Joachim Audet,&nbsp;Rachel Burns,&nbsp;Klaus Butterbach-Bahl,&nbsp;Mikk Espenberg,&nbsp;Christian Fritz,&nbsp;Stephan Glatzel,&nbsp;Gerald Jurasinski,&nbsp;Tuula Larmola,&nbsp;Ülo Mander,&nbsp;Claudia Nielsen,&nbsp;Andres F. Rodriguez,&nbsp;Clemens Scheer,&nbsp;Dominik Zak,&nbsp;Hanna M. Silvennoinen","doi":"10.1007/s10533-024-01122-6","DOIUrl":"10.1007/s10533-024-01122-6","url":null,"abstract":"<div><p>Restoration of drained peatlands through rewetting has recently emerged as a prevailing strategy to mitigate excessive greenhouse gas emissions and re-establish the vital carbon sequestration capacity of peatlands. Rewetting can help to restore vegetation communities and biodiversity, while still allowing for extensive agricultural management such as paludiculture. Belowground processes governing carbon fluxes and greenhouse gas dynamics are mediated by a complex network of microbial communities and processes. Our understanding of this complexity and its multi-factorial controls in rewetted peatlands is limited. Here, we summarize the research regarding the role of soil microbial communities and functions in driving carbon and nutrient cycling in rewetted peatlands including the use of molecular biology techniques in understanding biogeochemical processes linked to greenhouse gas fluxes. We emphasize that rapidly advancing molecular biology approaches, such as high-throughput sequencing, are powerful tools helping to elucidate the dynamics of key biogeochemical processes when combined with isotope tracing and greenhouse gas measuring techniques. Insights gained from the gathered studies can help inform efficient monitoring practices for rewetted peatlands and the development of climate-smart restoration and management strategies.</p></div>","PeriodicalId":8901,"journal":{"name":"Biogeochemistry","volume":"167 4","pages":"609 - 629"},"PeriodicalIF":3.9,"publicationDate":"2024-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10533-024-01122-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140139405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Labile organic matter promotes nitrogen retention in natural and constructed gulf coast marshes","authors":"S. F. Starr,&nbsp;B. Mortazavi,&nbsp;C. Tatariw,&nbsp;K. A. Kuehn,&nbsp;J. A. Cherry,&nbsp;T. Ledford,&nbsp;E. Smyth,&nbsp;A. Griffin Wood,&nbsp;S. E. Sebren","doi":"10.1007/s10533-024-01128-0","DOIUrl":"10.1007/s10533-024-01128-0","url":null,"abstract":"<div><p>Coastal marshes mitigate allochthonous nitrogen (N) inputs to adjacent marine habitat; however, their extent is declining rapidly. As a result, marsh restoration and construction have become a major foci of wetland management. Constructed marshes can quickly reach similar plant biomass to natural marshes, but biogeochemical functions like N removal and retention can take decades to reach functional equivalency, often due to lags in organic matter (OM) pools development in newly constructed marshes. We compared denitrification and dissimilatory nitrate reduction to ammonium (DNRA) rates in a 32 year-old constructed marsh and adjacent reference marsh in the Northern Gulf of Mexico. Marsh sediments packed into 3 mm “thin discs” were subjected to three OM quality treatments (no OM addition, labile OM, or recalcitrant OM) and two N treatments (ambient nitrate or elevated nitrate) during a 13 day incubation. We found that OM addition, rather than marsh type or nitrate treatment, was the most important driver of nitrate reduction, increasing both denitrification and DNRA and promoting DNRA over denitrification in both marshes. Fungal and bacterial biomass were higher in the natural marsh across treatments, but recalcitrant OM increased fungal biomass in the constructed marsh, suggesting OM-limitation of fungal growth. We found that constructed marshes are capable of similar denitrification and DNRA as natural marshes after 30 years, and that labile OM addition promotes N retention in both natural and constructed marshes.</p><h3>Graphical Abstract</h3><p>Conceptual figure highlighting the findings of this experiment. Under control treatment with no C addition (bottom panel), constructed and natural marshes have similar rates of both DNRA and denitrification. The natural marsh has higher fungal and bacterial biomass, while fungal biomass is not detectable in the constructed marsh. Under labile OM additions (upper left panel), rates of both DNRA and denitrification are increased and DNRA becomes favored over denitrification in both marshes. Recalcitrant OM additions (upper right) increase denitrification, but do not affect DNRA or % denitrification. The addition of recalcitrant OM also increases the detectability of fungal biomass in the constructed marsh.</p><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":8901,"journal":{"name":"Biogeochemistry","volume":"167 3","pages":"269 - 285"},"PeriodicalIF":3.9,"publicationDate":"2024-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10533-024-01128-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140124081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Disentangling effects of multiple agricultural stressors on benthic and hyporheic nitrate uptake","authors":"Julia Pasqualini,&nbsp;Daniel Graeber,&nbsp;Alexander Bartusch,&nbsp;Steffen Kümmel,&nbsp;Zulma Lorena Duran Hernandez,&nbsp;Niculina Musat,&nbsp;Nergui Sunjidmaa,&nbsp;Markus Weitere,&nbsp;Mario Brauns","doi":"10.1007/s10533-024-01130-6","DOIUrl":"10.1007/s10533-024-01130-6","url":null,"abstract":"<div><p>Agricultural land use alters nitrate (NO₃^–) uptake dynamics in streams, but the specific mechanisms linking individual agricultural stressors to benthic and hyporheic uptake remain unclear. Using stream-side mesocosms and ¹⁵N-nitrate additions, we examined the individual and combined effects of fine sediment (FS) and augmented light and phosphorus levels (L&amp;P) on benthic and hyporheic NO₃^– uptake rates. In absence of FS, L&amp;P stimulated uptake of autotrophic and heterotrophic biofilms, leading to a 12- and 7-fold increase in the benthic and hyporheic compartments, respectively. Under ambient light and nutrient conditions, FS reduced by 3-fold benthic uptake, but effects were not significant. Conversely, in the hyporheic compartment, FS induced anoxic conditions, likely stimulating denitrification and causing a 14-fold increase in hyporheic uptake. When these stressors were combined, they did not interact in the benthic compartment. Conversely, in the hyporheic compartment they interacted antagonistically, with L&amp;P diminishing the increase in uptake induced by FS. Our results indicate that the previously observed increase of whole-stream NO₃^– uptake in agricultural streams is attributable to nutrients and light stimulating benthic uptake, while fine sediment effects and the role of the hyporheic compartment to total uptake are modest. Moreover, the finding that stressor interactions vary with ecosystem compartments calls for a consideration of all compartments and their contribution to whole-system functioning in multiple stressor studies. We are beginning to understand how multiple interacting stressors affect stream functioning, but more mechanistic evidence is needed to disentangle whether additive or non-additive effects prevail in human-altered ecosystems.</p></div>","PeriodicalId":8901,"journal":{"name":"Biogeochemistry","volume":"167 3","pages":"287 - 299"},"PeriodicalIF":3.9,"publicationDate":"2024-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10533-024-01130-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140114420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Disentangling the effects of temperature and reactive minerals on soil carbon stocks across a thermal gradient in a temperate native forest ecosystem","authors":"Idri Hastuty Siregar,&nbsp;Marta Camps-Arbestain,&nbsp;Gabor Kereszturi,&nbsp;Alan Palmer,&nbsp;Miko U. F. Kirschbaum,&nbsp;Tao Wang","doi":"10.1007/s10533-024-01125-3","DOIUrl":"10.1007/s10533-024-01125-3","url":null,"abstract":"<div><p>Effects of global warming on soil organic carbon (C) can be investigated by comparing sites experiencing different temperatures. However, observations can be affected by covariance of temperature with other environmental properties. Here, we studied a thermal gradient in forest soils derived from volcanic materials on Mount Taranaki (New Zealand) to disentangle the effects of temperature and reactive minerals on soil organic C quantity and composition. We collected soils at four depths and four elevations with mean annual temperatures ranging from 7.3 to 10.5 °C. Soil C stocks were not significantly different across sites (average 162 MgC ha⁻¹ to 85 cm depth,<i> P</i> &gt; .05). Neither aluminium (Al)-complexed C, nor mineral-associated C changed significantly (<i>P</i> &gt; .05) with temperature. The molecular characterisation of soil organic matter showed that plant-derived C declined with increasing temperature, while microbial-processed C increased. Accompanying these changes, soil short-range order (SRO) constituents (including allophane) generally increased with temperature. Results from structural equation modelling revealed that, although a warmer temperature tended to accelerate soil organic C decomposition as inferred from molecular fingerprints, it also exerted a positive effect on soil total C presumably by enhancing plant C input. Despite a close linkage between mineral-associated C and soil organic C, the increased abundance of reactive minerals at 30–85 cm depth with temperature did not increase soil organic C concentration at that depth. We therefore propose that fresh C inputs, rather than reactive minerals, mediate soil C responses to temperature across the thermal gradient of volcanic soils under humid-temperate climatic conditions.</p></div>","PeriodicalId":8901,"journal":{"name":"Biogeochemistry","volume":"167 3","pages":"251 - 267"},"PeriodicalIF":3.9,"publicationDate":"2024-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10533-024-01125-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140096965","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rivers and tidal flats as sources of dissolved organic matter and trace metals in the German Bight (North Sea)","authors":"Linn G. Speidel,&nbsp;Roger Carvalho da Silva,&nbsp;Melanie Beck,&nbsp;Olaf Dellwig,&nbsp;Jochen Wollschläger,&nbsp;Thorsten Dittmar,&nbsp;Michael Seidel","doi":"10.1007/s10533-024-01117-3","DOIUrl":"10.1007/s10533-024-01117-3","url":null,"abstract":"<div><p>The German Bight in the southern North Sea receives nutrients, dissolved organic matter (DOM), and trace metals from rivers, porewater reflux, and porewater outwelling. We studied the marine, riverine, and porewater sources analyzing molecular transformations of solid-phase extracted (SPE) DOM in the German Bight. We applied a combination of ultrahigh-resolution mass spectrometry (FT-ICR-MS) with quantitative data of dissolved organic sulfur (DOS), dissolved black carbon (DBC), dissolved trace metals (Ba, Co, Gd, Mo, Mn, W), and nutrients (nitrite, nitrate, phosphate, silicate). While aromatic DOM and DBC mainly originated from the rivers, nitrogen-containing, more saturated DOM was enriched offshore suggesting greater contributions of marine (algal) sources. Except for dissolved Mo, rivers were the primary source of trace metals and nutrients. However, tidal flats contributed to dissolved nutrient (e.g., dissolved phosphate), trace metal and DOS inventories of the southern North Sea. The input of DOS from intertidal flats was identified by the molecular index derived from sulfidic porewaters (I_SuP), non-conservative behavior of elemental sulfur-to-carbon ratio and sulfur content of molecular formulae (from FT-ICR-MS). Dissolved Mn and Si were removed in the German Bight, likely due to precipitation as Mn(hydr)oxides and biological uptake, respectively. Preliminary estimates suggest that DOS from porewater outwelling is approximately four times higher than DOS discharged by the three main rivers in the region. Our study therefore highlights the need to consider porewater discharge in addition to riverine sources to comprehensively assess elemental budgets within the complex interplay and transformations of DOM, nutrients, and trace metals in coastal ecosystems.</p></div>","PeriodicalId":8901,"journal":{"name":"Biogeochemistry","volume":"167 3","pages":"225 - 250"},"PeriodicalIF":3.9,"publicationDate":"2024-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10533-024-01117-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140096895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Permafrost degradation and its consequences for carbon storage in soils of Interior Alaska","authors":"Patrick Liebmann,&nbsp;Jiří Bárta,&nbsp;Cordula Vogel,&nbsp;Tim Urich,&nbsp;Alexander Kholodov,&nbsp;Milan Varsadiya,&nbsp;Ole Mewes,&nbsp;Stefan Dultz,&nbsp;Muhammad Waqas,&nbsp;Haitao Wang,&nbsp;Olga Shibistova,&nbsp;Georg Guggenberger","doi":"10.1007/s10533-024-01132-4","DOIUrl":"10.1007/s10533-024-01132-4","url":null,"abstract":"<div><p>Permafrost soils in the northern hemisphere are known to harbor large amounts of soil organic matter (SOM). Global climate warming endangers this stable soil organic carbon (SOC) pool by triggering permafrost thaw and deepening the active layer, while at the same time progressing soil formation. But depending, e.g., on ice content or drainage, conditions in the degraded permafrost can range from water-saturated/anoxic to dry/oxic, with concomitant shifts in SOM stabilizing mechanisms. In this field study in Interior Alaska, we investigated two sites featuring degraded permafrost, one water-saturated and the other well-drained, alongside a third site with intact permafrost. Soil aggregate- and density fractions highlighted that permafrost thaw promoted macroaggregate formation, amplified by the incorporation of particulate organic matter, in topsoils of both degradation sites, thus potentially counteracting a decrease in topsoil SOC induced by the permafrost thawing. However, the subsoils were found to store notably less SOC than the intact permafrost in all fractions of both degradation sites. Our investigations revealed up to net 75% smaller SOC storage in the upper 100 cm of degraded permafrost soils as compared to the intact one, predominantly related to the subsoils, while differences between soils of wet and dry degraded landscapes were minor. This study provides evidence that the consideration of different permafrost degradation landscapes and the employment of soil fractionation techniques is a useful combination to investigate soil development and SOM stabilization processes in this sensitive ecosystem.</p></div>","PeriodicalId":8901,"journal":{"name":"Biogeochemistry","volume":"167 3","pages":"199 - 223"},"PeriodicalIF":3.9,"publicationDate":"2024-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10533-024-01132-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140096857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}