Biogeosciences最新文献

{"title":"Seasonal cycles of biogeochemical fluxes in the Scotia Sea, Southern Ocean: a stable isotope approach","authors":"A. Belcher, S. Henley, K. Hendry, M. Wootton, L. Friberg, Ursula Dallman, Tongli Wang, C. Coath, C. Manno","doi":"10.5194/bg-20-3573-2023","DOIUrl":"https://doi.org/10.5194/bg-20-3573-2023","url":null,"abstract":"Abstract. The biological carbon pump is responsible for much of the decadal\u0000variability in the ocean carbon dioxide (CO2) sink, driving the\u0000transfer of carbon from the atmosphere to the deep ocean. A mechanistic\u0000understanding of the ecological drivers of particulate organic carbon (POC)\u0000flux is key both to the assessment of the magnitude of the ocean CO2\u0000sink and for accurate predictions as to how this will change with\u0000changing climate. This is particularly important in the Southern Ocean, a\u0000key region for the uptake of CO2 and the supply of nutrients to the\u0000global thermocline. In this study we examine sediment-trap-derived particle\u0000fluxes and stable isotope signatures of carbon (C), nitrogen (N), and\u0000biogenic silica (BSi) at a study site in the biologically productive waters\u0000of the northern Scotia Sea in the Southern Ocean. Both deep (2000 m) and\u0000shallow (400 m) sediment traps exhibited two main peaks in POC, particulate\u0000N, and BSi flux: one in austral spring and one in summer, reflecting periods\u0000of high surface productivity. Particulate fluxes and isotopic compositions\u0000were similar in both deep and shallow sediment traps, highlighting that most\u0000remineralisation occurred in the upper 400 m of the water column.\u0000Differences in the seasonal cycles of isotopic compositions of C, N, and Si\u0000provide insights into the degree of coupling of these key nutrients. We\u0000measured increasing isotopic enrichment of POC and BSi in spring, consistent\u0000with fractionation during biological uptake. Since we observed isotopically\u0000light particulate material in the traps in summer, we suggest\u0000physically mediated replenishment of lighter isotopes of key nutrients from\u0000depth, enabling the full expression of the isotopic fractionation associated\u0000with biological uptake. The change in the nutrient and remineralisation\u0000regimes, indicated by the different isotopic compositions of the spring and\u0000summer productive periods, suggests a change in the source region of\u0000material reaching the traps and associated shifts in phytoplankton community\u0000structure. This, combined with the occurrence of advective inputs at certain\u0000times of the year, highlights the need to make synchronous measurements of\u0000physical processes to improve our ability to track changes in the source\u0000regions of sinking particulate material. We also highlight the need to\u0000conduct particle-specific (e.g. faecal pellets, phytoplankton detritus,\u0000zooplankton moults) isotopic analysis to improve the use of this tool in\u0000assessing particle composition of the sinking material and to develop our\u0000understanding of the drivers of biogeochemical fluxes.\u0000","PeriodicalId":8899,"journal":{"name":"Biogeosciences","volume":" ","pages":""},"PeriodicalIF":4.9,"publicationDate":"2023-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47038962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enabling a process-oriented hydro-biogeochemical model to simulate soil erosion and nutrient losses","authors":"Siqi Li, B. Zhu, Xunhua Zheng, Pengcheng Hu, Shenghui Han, Ji-hui Fan, Tao Wang, Rui Wang, Kai Wang, Z. Yao, Chunyan Liu, Wei Zhang, Y. Li","doi":"10.5194/bg-20-3555-2023","DOIUrl":"https://doi.org/10.5194/bg-20-3555-2023","url":null,"abstract":"Abstract. Water-induced erosion and associated particulate carbon (PC), particulate nitrogen (PN)\u0000and particulate phosphorus (PP) nutrient losses are vital parts of biogeochemical\u0000cycling. Identifying their intensity and distribution characteristics is of\u0000great significance for the control of soil and water loss and nitrogen/phosphorus nonpoint\u0000source pollution. This study incorporated modules of physical soil\u0000erosion and associated PC, PN and PP losses into a process-oriented\u0000hydro-biogeochemical model (Catchment Nutrients Management Model coupled with\u0000DeNitrification–DeComposition, CNMM-DNDC) to enable it to predict soil and\u0000water loss. The results indicated that the upgraded CNMM-DNDC (i) performed\u0000well in simulating the observed temporal dynamics and magnitudes of surface\u0000runoff, sediment and PN/PP yields in the lysimetric plot of the\u0000Jieliu catchment in Sichuan Province and (ii) successfully predicted the\u0000observed monthly dynamics and magnitudes of stream flow, sediment yield and\u0000PN yields at the catchment outlet, with significant univariate\u0000linear regressions and acceptable Nash–Sutcliffe indices higher than 0.74.\u0000The upgraded CNMM-DNDC demonstrated that a greater proportion of PN to total nitrogen (TN) during the period with large precipitation events and amounts than that during\u0000the drought period (16.2 %–26.6 % versus 2.3 %–12.4 %). The\u0000intensities of soil erosion and particulate nutrient yields in the Jieliu\u0000catchment were closely related to land use type in the following order: sloping\u0000cultivated upland (SU) > residential areas (RA) > forest land (FL).\u0000The scenario analysis demonstrated that high greenhouse gas (GHG) emissions\u0000scenarios provided a greater risk of soil erosion than did low GHG emissions\u0000scenarios and that land use change (i.e., from SU to FL)\u0000could help to mitigate soil and water loss accelerated by climate change in\u0000the future. The upgraded model was demonstrated to have the ability of\u0000predicting ecosystem productivity, hydrologic nitrogen loads, emissions of\u0000GHGs and pollutant gases, soil erosion and particulate nutrient yields,\u0000which renders it a potential decision support tool for soil erosion and\u0000nonpoint source pollution control coordinated with increasing production and\u0000reducing GHG and pollutant gases emissions in a catchment.\u0000","PeriodicalId":8899,"journal":{"name":"Biogeosciences","volume":" ","pages":""},"PeriodicalIF":4.9,"publicationDate":"2023-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49541464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gross primary productivity and the predictability of CO2: more uncertainty in what we predict than how well we predict it","authors":"I. Dunkl, N. Lovenduski, Alessio Collalti, V. Arora, T. Ilyina, V. Brovkin","doi":"10.5194/bg-20-3523-2023","DOIUrl":"https://doi.org/10.5194/bg-20-3523-2023","url":null,"abstract":"Abstract. The prediction of atmospheric CO2 concentrations is limited by the high interannual variability (IAV) in terrestrial gross primary\u0000productivity (GPP). However, there are large uncertainties in the drivers of GPP IAV among Earth system models (ESMs). Here, we evaluate the impact\u0000of these uncertainties on the predictability of atmospheric CO2 in six ESMs. We use regression analysis to determine the role of\u0000environmental drivers in (i) the patterns of GPP IAV and (ii) the predictability of GPP. There are large uncertainties in the spatial distribution\u0000of GPP IAV. Although all ESMs agree on the high IAV in the tropics, several ESMs have unique hotspots of GPP IAV. The main driver of GPP IAV is\u0000temperature in the ESMs using the Community Land Model, whereas it is soil moisture in the ESM developed by the Institute Pierre Simon Laplace (IPSL-CM6A-LR) and in the low-resolution configuration of the Max Planck Earth System Model (MPI-ESM-LR), revealing underlying differences in the\u0000source of GPP IAV among ESMs. Between 13 % and 24 % of the GPP IAV is predictable 1 year ahead, with four out of six ESMs showing values of between 19 %\u0000and 24 %. Up to 32 % of the GPP IAV induced by soil moisture is predictable, whereas only 7 % to 13 % of the GPP IAV induced by\u0000radiation is predictable. The results show that, while ESMs are fairly similar in their ability to predict their own carbon flux variability, these predicted contributions to the atmospheric CO2 variability originate from different regions and are caused by different drivers. A higher coherence in atmospheric\u0000CO2 predictability could be achieved by reducing uncertainties in the GPP sensitivity to soil moisture and by accurate observational products\u0000for GPP IAV.\u0000","PeriodicalId":8899,"journal":{"name":"Biogeosciences","volume":" ","pages":""},"PeriodicalIF":4.9,"publicationDate":"2023-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48816060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ideas and perspectives: The fluctuating nature of oxygen shapes the ecology of aquatic habitats and their biogeochemical cycles – the aquatic oxyscape","authors":"Marco Fusi, Sylvain Rigaud, Giovanna Guadagnin, Alberto Barausse, Ramona Marasco, Daniele Daffonchio, Julie Régis, Louison Huchet, Capucine Camin, Laura Pettit, Cristina Vina-Herbon, Folco Giomi","doi":"10.5194/bg-20-3509-2023","DOIUrl":"https://doi.org/10.5194/bg-20-3509-2023","url":null,"abstract":"Abstract. Oxygen availability is a pivotal factor for ecosystem functioning and the resistance of organisms to the effect of climate change in aquatic habitats. Although extensive work has been done to assess the effect of oxygen on marine and freshwater biota, many studies have not captured the ecological importance of oxygen variations. Overlooking the fluctuating nature of oxygen may cause potential biases in the design and implementation of management policies for aquatic habitats. Conceptual perspectives on the dynamic nature of oxygen fluctuations have been raised in the scientific community in order to enhance the understanding of the effect of oxygen on the physiology and the ecology of aquatic species as well as the biogeochemical functioning of their ecosystems. A growing number of empirical work has been outlining a novel conceptual framework that considers the magnitude of oxygen fluctuation as a key variable that explains adaptation to stress conditions. Oxygen in productive aquatic habitats shows large fluctuations at the diel scale, exposing aquatic species to conditions ranging from extreme supersaturation to anoxia. Recent research has indicated that such a fluctuation tunes the physiological plasticity of the animal in response to thermal stresses. In this paper, we provide compelling evidence based on current research that the fluctuating oxygen landscape, here defined as “oxyscape”, has an important role in aquatic animal physiology and adaptation as well as the ecosystem biogeochemistry. We propose that the oxyscape should be considered in the modelling and managing policies of aquatic ecosystems.","PeriodicalId":8899,"journal":{"name":"Biogeosciences","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135520481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sources and sinks of carbonyl sulfide inferred from tower and mobile atmospheric observations in the Netherlands","authors":"Alessandro Zanchetta, Linda M. J. Kooijmans, S. V. van Heuven, A. Scifo, H. Scheeren, I. Mammarella, U. Karstens, Jin Ma, M. Krol, Huilin Chen","doi":"10.5194/bg-20-3539-2023","DOIUrl":"https://doi.org/10.5194/bg-20-3539-2023","url":null,"abstract":"Abstract. Carbonyl sulfide (COS) is a promising tracer for the estimation of\u0000terrestrial ecosystem gross primary production (GPP). However, understanding\u0000its non-GPP-related sources and sinks, e.g., anthropogenic sources and soil\u0000sources and sinks, is also critical to the success of the approach. Here we\u0000infer the regional sources and sinks of COS using continuous in situ mole fraction\u0000profile measurements of COS along the 60 m tall Lutjewad tower (1 m a.s.l.;\u000053∘24′ N, 6∘21′ E) in the Netherlands. To identify\u0000potential sources that caused the observed enhancements of COS mole\u0000fractions at Lutjewad, both discrete flask samples and in situ measurements\u0000in the province of Groningen were made from a mobile van using a quantum\u0000cascade laser spectrometer (QCLS). We also simulated the COS mole fractions\u0000at Lutjewad using the Stochastic Time-Inverted Lagrangian Transport (STILT)\u0000model combined with emission inventories and plant uptake fluxes. We\u0000determined the nighttime COS fluxes to be -3.0±2.6 pmol m−2 s−1 using the radon-tracer correlation approach and Lutjewad\u0000observations. Furthermore, we identified and quantified several COS sources,\u0000including biodigesters, sugar production facilities and silicon carbide\u0000production facilities in the province of Groningen. Moreover, the simulation\u0000results show that the observed COS enhancements can be partially explained\u0000by known industrial sources of COS and CS2, in particular from the Ruhr\u0000Valley (51.5∘ N, 7.2∘ E) and Antwerp (51.2∘ N,\u00004.4∘ E) areas. The contribution of likely missing anthropogenic\u0000sources of COS and CS2 in the inventory may be significant. The impact\u0000of the identified sources in the province of Groningen is estimated to be\u0000negligible in terms of the observed COS enhancements. However, in specific\u0000conditions, these sources may influence the measurements in Lutjewad. These\u0000results are valuable for improving our understanding of the sources and\u0000sinks of COS, contributing to the use of COS as a tracer for GPP.\u0000","PeriodicalId":8899,"journal":{"name":"Biogeosciences","volume":" ","pages":""},"PeriodicalIF":4.9,"publicationDate":"2023-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47271870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The contrasted phytoplankton dynamics across a frontal system in the southwestern Mediterranean Sea","authors":"Roxane Tzortzis, A. Doglioli, S. Barrillon, A. Petrenko, Lloyd Izard, Yuan Zhao, F. d’Ovidio, F. Dumas, G. Grégori","doi":"10.5194/bg-20-3491-2023","DOIUrl":"https://doi.org/10.5194/bg-20-3491-2023","url":null,"abstract":"Abstract. Numerical simulations have shown that finescale structures such as fronts are often suitable places for the generation of vertical velocities,\u0000transporting subsurface nutrients to the euphotic zone and thus modulating phytoplankton abundance and community structure. In these structures,\u0000direct in situ estimations of the phytoplankton growth rates are rare; although difficult to obtain, they provide precious information on the\u0000ecosystem functioning. Here, we consider the case of a front separating two water masses characterized by several phytoplankton groups with\u0000different abundances in the southwestern Mediterranean Sea. In order to estimate possible differences in growth rates, we measured the\u0000phytoplankton diurnal cycle in these two water masses as identified by an adaptive and Lagrangian sampling strategy. A size-structured population\u0000model was then applied to these data to estimate the growth and loss rates for each phytoplankton group identified by flow cytometry, showing that\u0000these two population parameters are significantly different on the two sides of the front and consistent with the relative abundances. Our results\u0000introduce a general method for estimating growth rates at frontal systems, paving the way for in situ exploration of finescale biophysical\u0000interactions.\u0000","PeriodicalId":8899,"journal":{"name":"Biogeosciences","volume":" ","pages":""},"PeriodicalIF":4.9,"publicationDate":"2023-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44524485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experiments of the efficacy of tree ring blue intensity as a climate proxy in central and western China","authors":"Yonghong Zheng, Huanfeng Shen, Rory Abernethy, Rob Wilson","doi":"10.5194/bg-20-3481-2023","DOIUrl":"https://doi.org/10.5194/bg-20-3481-2023","url":null,"abstract":"Abstract. To investigate the potential value of tree ring blue intensity as a robust\u0000climate proxy in central and western China, four species from five sites were\u0000assessed. As well as latewood inverted blue intensity, we also examined\u0000earlywood blue intensity. To explore the sensitivity of using different\u0000extraction parameter settings using the software CooRecorder, seven\u0000percentile (P) variant settings for earlywood blue intensity and latewood\u0000inverted blue intensity were used, namely P50 : 50, P60 : 40, P70 : 30, P80 : 20,\u0000P85 : 15, P90 : 10, and P95 : 5. Age-dependent spline was used for all, and the\u0000positive trends were not retained. Correlation analysis was applied between\u0000the tree ring parameter chronologies and monthly/seasonal mean temperature,\u0000precipitation, and self-calibrated Palmer drought severity index variables.\u0000Linear regression was also used to further highlight the potential of\u0000developing climate reconstructions using these species. Only subtle\u0000differences were found between the different percentile extraction variants.\u0000As has been shown for many other Northern Hemisphere studies, latewood\u0000inverted blue intensity expresses a strong positive relationship with\u0000growing-season temperatures (the two southern sites explain almost 56 % of\u0000the temperature variance when combined). However, the low latitude of these\u0000sites shows an exciting potential for regions south of 30∘ N that are\u0000traditionally not targeted for temperature reconstructions. Earlywood blue\u0000intensity also shows good potential to reconstruct hydroclimate parameters\u0000in some humid areas.\u0000","PeriodicalId":8899,"journal":{"name":"Biogeosciences","volume":" ","pages":""},"PeriodicalIF":4.9,"publicationDate":"2023-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41782090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Potential bioavailability of representative pyrogenic organic matter compounds in comparison to natural dissolved organic matter pools","authors":"E. Graham, Hyun‐Seob Song, S. Grieger, V. Garayburu-Caruso, J. Stegen, K. Bladon, A. Myers‐Pigg","doi":"10.5194/bg-20-3449-2023","DOIUrl":"https://doi.org/10.5194/bg-20-3449-2023","url":null,"abstract":"Abstract. Pyrogenic organic matter (PyOM) from wildfires impacts river\u0000corridors globally and is widely regarded as resistant to biological\u0000degradation. Though recent work suggests PyOM may be more bioavailable than\u0000historically perceived, estimating bioavailability across its chemical\u0000spectrum remains elusive. To address this knowledge gap, we assessed\u0000potential bioavailability of representative PyOM compounds relative to\u0000ubiquitous dissolved organic matter (DOM) with a substrate-explicit model.\u0000The range of potential bioavailability of PyOM was greater than natural DOM;\u0000however, the predicted thermodynamics, metabolic rates, and carbon use\u0000efficiencies (CUEs) overlapped significantly between all OM pools. Compound type\u0000(e.g., natural versus PyOM) had approximately 6-fold less impact on predicted\u0000respiration rates than simulated carbon and oxygen limitations. Within PyOM,\u0000the metabolism of specific chemistries differed strongly between unlimited\u0000and oxygen-limited conditions – degradations of anhydrosugars, phenols, and polycyclic aromatic hydrocarbons (PAHs) were more favorable under oxygen\u0000limitation than other molecules. Notably, amino sugar-like, protein-like, and lignin-like PyOM had lower carbon use efficiencies relative to natural DOM\u0000of the same classes, indicating potential impacts in process-based model\u0000representations. Overall, our work illustrates how similar PyOM\u0000bioavailability may be to that of natural DOM in the river corridor,\u0000furthering our understanding of how PyOM may influence riverine\u0000biogeochemical cycling.\u0000","PeriodicalId":8899,"journal":{"name":"Biogeosciences","volume":" ","pages":""},"PeriodicalIF":4.9,"publicationDate":"2023-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41516535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Alkalinity generation from carbonate weathering in a silicate-dominated headwater catchment at Iskorasfjellet, northern Norway","authors":"N. Lehmann, H. Lantuit, M. Böttcher, J. Hartmann, A. Eulenburg, H. Thomas","doi":"10.5194/bg-20-3459-2023","DOIUrl":"https://doi.org/10.5194/bg-20-3459-2023","url":null,"abstract":"Abstract. The weathering rate of carbonate minerals is several\u0000orders of magnitude higher than for silicate minerals. Therefore, small\u0000amounts of carbonate minerals have the potential to control the dissolved\u0000weathering loads in silicate-dominated catchments. Both weathering processes\u0000produce alkalinity under the consumption of CO2. Given that only\u0000alkalinity generation from silicate weathering is thought to be a long-term\u0000sink for CO2, a misattributed weathering source could lead to incorrect\u0000conclusions about long- and short-term CO2 fixation. In this study, we\u0000aimed to identify the weathering sources responsible for alkalinity\u0000generation and CO2 fixation across watershed scales in a degrading\u0000permafrost landscape in northern Norway, 68.7–70.5∘ N, and on\u0000a temporal scale, in a subarctic headwater catchment on the mountainside of\u0000Iskorasfjellet, characterized by sporadic permafrost and underlain mainly by\u0000silicates as the alkalinity-bearing lithology. By analyzing total alkalinity\u0000(AT) and dissolved inorganic carbon (DIC) concentrations, as well as the\u0000stable isotope signature of the latter (δ13C-DIC), in\u0000conjunction with dissolved cation and anion loads, we found that AT was\u0000almost entirely derived from weathering of the sparse carbonate minerals. We\u0000propose that in the headwater catchment the riparian zone is a hotspot area\u0000of AT generation and release due to its enhanced hydrological connectivity\u0000and that the weathering load contribution from the uphill catchment is\u0000limited by insufficient contact time of weathering agents and weatherable\u0000materials. By using stable water isotopes, it was possible to explain\u0000temporal variations in AT concentrations following a precipitation event due\u0000to surface runoff. In addition to carbonic acid, sulfuric acid, probably\u0000originating from oxidation of pyrite or reduced sulfur in wetlands or from\u0000acid deposition, is shown to be a potential corrosive reactant. An increased\u0000proportion of sulfuric acid as a potential weathering agent may have\u0000resulted in a decrease in AT. Therefore, carbonate weathering in the studied\u0000area should be considered not only as a short-term CO2 sink but also\u0000as a potential CO2 source. Finally, we found that AT increased with\u0000decreasing permafrost probability, and attributed this relation to an\u0000increased water storage capacity associated with increasing contact of\u0000weathering agent and rock surfaces and enhanced microbial activity. As both\u0000soil respiration and permafrost thaw are expected to increase with climate\u0000change, increasing the availability of weathering agents in the form of\u0000CO2 and water storage capacity, respectively, we suggest that future\u0000weathering rates and alkalinity generation will increase concomitantly in\u0000the study area.\u0000","PeriodicalId":8899,"journal":{"name":"Biogeosciences","volume":" ","pages":""},"PeriodicalIF":4.9,"publicationDate":"2023-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48359161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Benthic foraminifera and gromiids from oxygen-depleted environments – survival strategies, biogeochemistry and trophic interactions","authors":"N. Glock","doi":"10.5194/bg-20-3423-2023","DOIUrl":"https://doi.org/10.5194/bg-20-3423-2023","url":null,"abstract":"Abstract. The oceans are losing oxygen (O2), and oxygen minimum zones are\u0000expanding due to climate warming (lower O2 solubility) and\u0000eutrophication related to agriculture. This trend is challenging for most\u0000marine taxa that are not well adapted to O2 depletion. For other taxa\u0000this trend might be advantageous because they can withstand low O2\u0000concentrations or thrive under O2-depleted or even anoxic conditions.\u0000Benthic foraminifera are a group of protists that include taxa with\u0000adaptations to partly extreme environmental conditions. Several species\u0000possess adaptations to O2 depletion that are rare amongst eukaryotes,\u0000and these species might benefit from ongoing ocean deoxygenation. In\u0000addition, since some foraminifera can calcify even under anoxic conditions,\u0000they are important archives for paleoceanographic reconstruction in O2-depleted environments. This paper reviews the current state of knowledge\u0000about foraminifera from low-O2 environments. Recent advances in our\u0000understanding of specific survival strategies of foraminifera to withstand O2\u0000depletion are summarized and discussed. These adaptations include an\u0000anaerobic metabolism, heterotrophic denitrification, symbiosis with\u0000bacteria, kleptoplasty and dormancy and have a strong impact on their\u0000preferred microhabitat in the sediments, especially the ability of some benthic foraminiferal species to denitrify. Benthic foraminifera also differ\u0000regarding their trophic strategies, which has an additional impact on the\u0000selection of their microhabitat. For example, some species are strict\u0000herbivores that feed exclusively on fresh phytodetritus and live close to\u0000the sediment surface, while some species are non-selective detrivores that\u0000occupy intermediate to deep infaunal habitats. There is evidence that\u0000foraminifers have the capacity to undergo phagocytosis, even under anoxia, and some\u0000foraminiferal species which can withstand low-O2 conditions seem to\u0000prey on meiofauna. Also, due to their high abundances in O2-depleted\u0000environments and their metabolic adaptations, benthic foraminifera are key\u0000players in marine nutrient cycling, especially within the marine N and P\u0000cycles. This review summarizes the denitrification rates for the species\u0000that are known to denitrify and the intracellular nitrate concentrations of\u0000the species that are known to intracellularly store nitrate. Finally,\u0000equations are provided that can be used to estimate the intracellular\u0000nutrient storage and denitrification rates of foraminifera and might be\u0000integrated into biogeochemical models.\u0000","PeriodicalId":8899,"journal":{"name":"Biogeosciences","volume":" ","pages":""},"PeriodicalIF":4.9,"publicationDate":"2023-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47682907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}