Limnology and Oceanography最新文献

{"title":"Dual phosphorus and nitrogen nutrient reduction will be more effective than a phosphorus‐only reduction in mitigating diatom and cyanobacterial blooms in Lake Erie, USA–Canada","authors":"Hans W. Paerl, Justin D. Chaffin, Jack H. Cheshire, Haley E. Plaas, Malcolm A. Barnard, Lillian B. Goerlitz, Jeremy S. Braddy, Alexandrea Sabo, Leah M. Nelson, Lindsay Yue","doi":"10.1002/lno.12719","DOIUrl":"https://doi.org/10.1002/lno.12719","url":null,"abstract":"Lake Erie, USA–Canada, plays an important ecological and socioeconomic role but has suffered from chronic eutrophication. In particular, western Lake Erie (WLE) is the site of harmful algal blooms (HABs) which are suspected of being driven by excessive nutrient (phosphorus (P) and nitrogen (N)) inputs. During 2022 and 2023, in situ nutrient dilution and addition bioassays were conducted at a WLE bloom‐impacted location to investigate whether a nutrient reduction regime would be effective in limiting phytoplankton growth during the June diatom‐dominated spring blooms and August cyanobacteria‐dominated summer blooms. The primary objectives of this experiment were to (1) Determine if a proposed 40% P‐alone reduction would effectively reduce phytoplankton growth and mitigate blooms and (2) assess whether reductions in both P and N are more effective in controlling phytoplankton biomass than exclusive reductions in either N or P. Samples were analyzed for nutrient concentrations and growth rate responses for specific algal groups, utilizing diagnostic (for major algal groups) photopigments. Results indicated that although both 20% and 40% dilutions led to lower phytoplankton biomass and growth rates, 40% reductions were more effective. Our results support the USA–Canada Great Lakes Water Quality Agreement recommendation of a 40% P reduction, but also indicate that a parallel reduction of N input by 40% would be most effective in controlling bloom magnitudes. Overall, our findings underscore the recommendation that a year‐round dual N and P 40% reduction is needed for long‐term control of eutrophication and algal blooms, including cyanobacteria and diatoms, in Lake Erie.","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142563159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Can intense storms affect sinking particle dynamics after the North Atlantic spring bloom?","authors":"Elisa Romanelli, Sarah Lou Carolin Giering, Margaret Estapa, David A. Siegel, Uta Passow","doi":"10.1002/lno.12723","DOIUrl":"https://doi.org/10.1002/lno.12723","url":null,"abstract":"The sinking of large particles (i.e., marine snow) has long been recognized as a key pathway for efficient particulate organic carbon (POC) export to the ocean interior during the decline of spring diatom blooms. Recent work has suggested that particles smaller than marine snow can also substantially contribute to POC export. However, a detailed characterization of small and large sinking particles at the end of blooms is missing. Here, we separately collected suspended and small and large sinking particles using Marine Snow Catchers and assessed their biogeochemical composition after the North Atlantic spring bloom in May 2021. During the 3 weeks of sampling, when four intense storms (maximum wind speeds 37–50 kt) created high turbulent kinetic energy dissipation rates and deepened the mixed layer, we observed two distinct sedimentation events. At first, sinking particles were dominated by small (diameter &lt; 0.1 mm), slowly sinking ( 18 m d<jats:sup>−1</jats:sup>), particles rich in silica that carried a moderate POC flux (&lt; 6 mmol C m<jats:sup>−2</jats:sup> d<jats:sup>−1</jats:sup>) to 500 m depth. Once the storms ceased, the volume of large (diameter &gt; 0.1 mm), fast‐sinking (&gt; 75 m d<jats:sup>−1</jats:sup>), carbon‐rich marine snow aggregates (not fecal pellets) increased exponentially and POC fluxes at 100 m depth were more than fourfold greater (30 ± 12 mmol C m<jats:sup>−2</jats:sup> d<jats:sup>−1</jats:sup>) than those during the previous event. The aggregates consisted of a mixed post‐bloom plankton community. Our data suggest that the storms shaped the timing, type, and magnitude of POC flux at the end of this spring phytoplankton bloom.","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142563040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Moderate and extreme warming under a varied resource supply alter the microzooplankton–phytoplankton coupling in North Sea coastal communities","authors":"Marco J. Cabrerizo, Anika Happe, Antonia Ahme, Uwe John, Markus Olsson, Maren Striebel","doi":"10.1002/lno.12718","DOIUrl":"https://doi.org/10.1002/lno.12718","url":null,"abstract":"Rising temperature is one of the most visible effects of global change on Earth; however, it is barely known how moderate or extreme warming events impact the trophic interactions and the energy transfer in food webs. Combining a mesocosm approach and two‐point dilution incubations, we quantified how natural plankton assemblages respond to moderate and extreme warming (+6°C vs. +12°C above ambient temperature), covering a nitrogen‐to‐phosphorus gradient from nutrient‐saturated to limited conditions. We addressed how both drivers altered the community structure and mediated the phytoplankton growth (<jats:italic>μ</jats:italic>) and microzooplankton grazing (<jats:italic>m</jats:italic>) rates. Moderate and extreme warming effects on the microzooplankton–phytoplankton relationship differed and were mediated by time. This trophic interaction was weakened due to <jats:italic>μ</jats:italic> outpacing <jats:italic>m</jats:italic> regardless of the warming treatment at the middle of the experiment. By contrast, after the acclimation period, the trophic interaction was strengthened by increased grazing under extreme warming. The variable grazing pressure found at different temporal scales only under extreme warming could be due to a decreased microzooplankton grazing pressure with increasing temperature when prey biomass is low, and vice versa. Also, it could be a consequence of a switch toward mixotrophy or that the temperatures experienced by grazers were suboptimal compared to their prey. Finally, we found that temperature was the main driver whereas resource availability played a minor role in this trophic interaction. As climate change will intensify in the future, food webs could be less productive but more efficient, and thus, potentially support a higher secondary production.","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142563158","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Relative size matters: Spawning substrate roughness size and spacing affect egg dislodgement and retention in the benthos","authors":"Jake Carman, Yingming Zhao, Josef D. Ackerman","doi":"10.1002/lno.12715","DOIUrl":"https://doi.org/10.1002/lno.12715","url":null,"abstract":"The consequences of hydrodynamic effects on survival of embryonic benthic organisms remain unknown. This is because the interaction of hydrodynamics and substrate roughness is complex, but it can be conceptualized in two dimensions by roughness flow regimes (isolated, wake interference, and skimming flow) or roughness types (<jats:italic>k</jats:italic>‐ and <jats:italic>d</jats:italic>‐type). We examined the effect of different roughness flow regimes/roughness types and roughness heights (<jats:italic>k</jats:italic>) on the dislodgement of walleye (<jats:italic>Sander vitreus</jats:italic>) eggs (2 mm diameter, ⌀) using a wall jet apparatus. We expected that lower wall shear stress (<jats:italic>τ</jats:italic><jats:sub>w</jats:sub>) would be required for dislodgement in more‐exposed/less‐sheltered roughness type/flow regimes (i.e., <jats:italic>k</jats:italic>‐type/isolated roughness flow) and when <jats:italic>k</jats:italic> ≤ ⌀. Surprisingly, the opposite was found, indicating that other mechanism(s) are also responsible for egg dislodgement on these rough surfaces. Hydrodynamic sheltering occurred when flow was directed over exposed eggs (<jats:italic>k</jats:italic> ≤ ⌀) adjacent to roughness elements effectively increasing their width, and thus requiring higher <jats:italic>τ</jats:italic><jats:sub>w</jats:sub> for rolling and then ejection. When <jats:italic>k</jats:italic> &gt; ⌀, eggs dislodgement likely occurred via the lower pressure in the eddies recirculating in the groove width between roughness elements, rather than due to <jats:italic>τ</jats:italic><jats:sub>w</jats:sub>. These results indicate the relevance of heterogeneous sorting and sizing of substrate elements to provide suitable spawning habitats in benthic environments.","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sargassum beaching on mangrove sediments shifts microbial and crab metabolisms and enhances blue carbon storage","authors":"Mathias Chynel, Gwenaël Abril, Mélissa Narayaninsamy, Loris Deirmendjian, Frédéric Guérin, Charlotte Dromard, Tarik Meziane","doi":"10.1002/lno.12725","DOIUrl":"https://doi.org/10.1002/lno.12725","url":null,"abstract":"Benthic metabolism and net carbon accumulation in mangroves sediments strongly depend on the quantity and quality of organic matter (OM) supplied, including material brought by coastal waters such as the macroalgae <jats:italic>Sargassum</jats:italic> spp. Mesocosms were used to assess the effect of eutrophication by <jats:italic>Sargassum</jats:italic> on mangrove sediments. The concentration of fatty acids (FAs), organic carbon and its carbon isotopic signature, and the sediments–air CO<jats:sub>2</jats:sub> fluxes were used to follow the evolution of sedimentary OM in surface and subsurface sediments for 60 d. <jats:italic>Sargassum</jats:italic> beaching shifted microbial and crab metabolism, leading to a preferential degradation of the labile fraction of OM from both <jats:italic>Sargassum</jats:italic> (δ<jats:sup>13</jats:sup>C = −17.7‰ and high concentration of essential FAs) and mangrove leaves (δ<jats:sup>13</jats:sup>C: −28.9‰ and high concentrations of 18:2ω6 and 18:3ω3). Fatty acids composition of crabs hepatopancreas revealed they preferentially fed on <jats:italic>Sargassum</jats:italic> and these invertebrates also increased the particulate OM tidal export. In addition, microbial activity at the sediment surface was enhanced, as revealed by strong production of branched FAs and higher CO<jats:sub>2</jats:sub> fluxes in mesocosms containing <jats:italic>Sargassum</jats:italic>. However, <jats:italic>Sargassum</jats:italic> beaching also increased the transfer and preservation of more refractory OM from mangrove leaves found in higher quantity in subsurface sediments (6–8 cm) after 60 d. Inputs of macroalgae induced a negative priming effect and enhanced the preservation of blue carbon in the sediments. This negative priming effect was enhanced by crab activities. These biotic interactions that include microbial communities apparently make mangrove efficient in storing carbon in a context of growing eutrophication of the tropical ocean.","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142490528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Different elemental stoichiometries of Fe‐limited Trichodesmium when grown under inorganic and organic phosphorus sources","authors":"Xuechao Wang, Thomas J. Browning, Eric P. Achterberg, Martha Gledhill","doi":"10.1002/lno.12716","DOIUrl":"https://doi.org/10.1002/lno.12716","url":null,"abstract":"&lt;jats:italic&gt;Trichodesmium&lt;/jats:italic&gt; spp. is a colonial diazotrophic cyanobacterium found in the oligotrophic (sub)tropical oceans, where its distribution is strongly regulated by the availability of phosphorus and iron. The bulk carbon : nitrogen : phosphorus elemental composition of phytoplankton has previously been shown to depart from classical “Redfield” values under nutrient‐limitation conditions. We hypothesized that the abundance of intracellular metabolites and the extended Redfield ratios of &lt;jats:italic&gt;Trichodesmium&lt;/jats:italic&gt;, including a range of trace elements, are variable in response to conditions of phosphorus and iron limitation that are found in the ocean. To test this, we grew &lt;jats:italic&gt;Trichodesmium&lt;/jats:italic&gt; under trace metal–controlled conditions, where phosphorus was supplied as either dissolved inorganic phosphorus (DIP) or dissolved organic phosphorus (DOP) from iron depleted to elevated levels. We found that the steady‐state extended Redfield ratios of &lt;jats:italic&gt;Trichodesmium&lt;/jats:italic&gt; under the iron‐depleted condition was (C&lt;jats:sub&gt;106&lt;/jats:sub&gt;N&lt;jats:sub&gt;15.82&lt;/jats:sub&gt;P&lt;jats:sub&gt;0.62&lt;/jats:sub&gt;)&lt;jats:sub&gt;1000&lt;/jats:sub&gt;Fe&lt;jats:sub&gt;2.26&lt;/jats:sub&gt;Zn&lt;jats:sub&gt;2.37&lt;/jats:sub&gt;Mn&lt;jats:sub&gt;1.68&lt;/jats:sub&gt;Cu&lt;jats:sub&gt;0.68&lt;/jats:sub&gt;Ni&lt;jats:sub&gt;0.31&lt;/jats:sub&gt;Mo&lt;jats:sub&gt;0.42&lt;/jats:sub&gt;Co&lt;jats:sub&gt;0.03&lt;/jats:sub&gt; for the DIP treatment where &lt;jats:italic&gt;Trichodesmium&lt;/jats:italic&gt; was under iron limitation, and (C&lt;jats:sub&gt;106&lt;/jats:sub&gt;N&lt;jats:sub&gt;13.89&lt;/jats:sub&gt;P&lt;jats:sub&gt;0.49&lt;/jats:sub&gt;)&lt;jats:sub&gt;1000&lt;/jats:sub&gt;Fe&lt;jats:sub&gt;3.38&lt;/jats:sub&gt;Zn&lt;jats:sub&gt;2.51&lt;/jats:sub&gt;Mn&lt;jats:sub&gt;0.97&lt;/jats:sub&gt;Cu&lt;jats:sub&gt;0.52&lt;/jats:sub&gt;Ni&lt;jats:sub&gt;0.42&lt;/jats:sub&gt;Mo&lt;jats:sub&gt;0.33&lt;/jats:sub&gt;Co&lt;jats:sub&gt;0.03&lt;/jats:sub&gt; for the DOP treatment where &lt;jats:italic&gt;Trichodesmium&lt;/jats:italic&gt; was under iron–phosphorus co‐limitation. Mean steady‐state cellular iron : carbon in the DIP treatment (iron limited) was only 50% of that in the control treatment, while zinc : carbon was elevated twofold. The average extended Redfield ratios following recovery from iron limitation was (C&lt;jats:sub&gt;106&lt;/jats:sub&gt;N&lt;jats:sub&gt;16.8&lt;/jats:sub&gt;P&lt;jats:sub&gt;0.7&lt;/jats:sub&gt;)&lt;jats:sub&gt;1000&lt;/jats:sub&gt;Fe&lt;jats:sub&gt;4.41&lt;/jats:sub&gt;Zn&lt;jats:sub&gt;1.44&lt;/jats:sub&gt;Mn&lt;jats:sub&gt;1&lt;/jats:sub&gt;Cu&lt;jats:sub&gt;0.52&lt;/jats:sub&gt;Ni&lt;jats:sub&gt;0.19&lt;/jats:sub&gt;Mo&lt;jats:sub&gt;0.3&lt;/jats:sub&gt;Co&lt;jats:sub&gt;0.03&lt;/jats:sub&gt; for the DIP and (C&lt;jats:sub&gt;106&lt;/jats:sub&gt;N&lt;jats:sub&gt;15.9&lt;/jats:sub&gt;P&lt;jats:sub&gt;0.73&lt;/jats:sub&gt;)&lt;jats:sub&gt;1000&lt;/jats:sub&gt;Fe&lt;jats:sub&gt;7.36&lt;/jats:sub&gt;Zn&lt;jats:sub&gt;2.24&lt;/jats:sub&gt;Mn&lt;jats:sub&gt;1.08&lt;/jats:sub&gt;Cu&lt;jats:sub&gt;0.71&lt;/jats:sub&gt;Ni&lt;jats:sub&gt;0.63&lt;/jats:sub&gt;Mo&lt;jats:sub&gt;0.38&lt;/jats:sub&gt;Co&lt;jats:sub&gt;0.02&lt;/jats:sub&gt; for the DOP treatment. No significant changes were observed in the carbon‐normalized abundance of targeted metabolites produced by &lt;jats:italic&gt;Trichodesmium&lt;/jats:italic&gt;, under the different treatments. These results suggest &lt;jats:italic&gt;Trichodesmium&lt;/jats:italic","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142490527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A temperature tipping point in hypoxic zone size","authors":"R. Eugene Turner, Nancy N. Rabalais, Cassandra N. Glaspie","doi":"10.1002/lno.12722","DOIUrl":"https://doi.org/10.1002/lno.12722","url":null,"abstract":"Temperature increases will have ubiquitous effects on aquatic food webs, from microbes to consumers, and affect the quality and quantity of carbon flows within and between water layers. A decline in the biological pump moving carbon from surface to lower layers is anticipated. We reviewed 37 years of data on hypoxic zone size and water quality in the northern Gulf of Mexico to determine if air and bottom water temperature increases (0.5°C decade<jats:sup>−1</jats:sup>) are significantly related to variations in its areal size. There was no significant decline in important river water quality in the 24 years since the national Hypoxia Action Plan was developed to reduce its size. Changes in the ratio of km<jats:sup>2</jats:sup> hypoxia per 1000 mt nitrate loading from the Mississippi River from 2000 to 2023 reveals a tipping point in the hypoxic zone size that is driven by ocean warming. Biological factors varying with temperature such as ectotherm growth rates, zooplankton grazing, cell sinking rates, and diatom sequestration of Si or N are apparently more important influences on recent hypoxic zone size than variations in physical factors. This tipping point may be common to similarly warmed and eutrophic coastal waters where warming will likely result in diminished oxygen deficiency (&lt; 2 mgO<jats:sub>2</jats:sub> L<jats:sup>−1</jats:sup>). Hypoxia and food web models assuming a stationary equipoise of nutrient loadings, ratios and food webs will be deficient as coastal waters warm further, coastal storm and hurricane frequency increase and land uses in the watershed are altered with climate change.","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142488828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High‐speed escape jumps in haptophytes: Mechanism and triggering fluid signal","authors":"Federica Miano, Seyed Saeed Asadzadeh, Fredrik Ryderheim, Anders Andersen, Thomas Kiørboe","doi":"10.1002/lno.12713","DOIUrl":"https://doi.org/10.1002/lno.12713","url":null,"abstract":"Some planktonic organisms can remotely sense and evade predators by powerful escape jumps. Remote perception typically happens through the fluid disturbance generated by the approaching predator or its feeding current. In copepods and ciliates with mechanosensors, the perception and jump mechanisms are well understood. But how some flagellates perceive the fluid disturbance and achieve similar relative speeds with only two flagella is less explored. Here, we examined the ability of three haptophytes, <jats:italic>Chrysochromulina simplex</jats:italic>, <jats:italic>Prymnesium polylepis</jats:italic>, and <jats:italic>Prymnesium parvum</jats:italic>, to sense and evade the fluid disturbance generated by the feeding current of a copepod nauplius. <jats:italic>Chrysochromulina simplex</jats:italic> has a long haptonema (14 cell diameters), while the haptonema of the two other species are shorter (1 and 0.5 cell diameters). Only <jats:italic>C. simplex</jats:italic> responded to the fluid disturbance by fleeing at high speeds. The jump mechanism consists of two phases: the rapid coiling of the haptonema that pulls the cell about two cell diameters in the direction of the haptonema, followed by flagellar reversal and high‐speed swimming (70 cell lengths per second) in the opposite direction. We rationalize cell displacements and escape speeds from haptonema and flagellar kinematics and fluid dynamics. Using a microfluidic channel, we demonstrate that the component of the fluid signal that triggers the jumps is the maximum deformation rate rather than the magnitude of deformation. High‐speed escape jumps may be an avoidance mechanism evolved by haptophytes with long and coiling haptonema, while species with shorter haptonema may use other defense mechanisms, such as stealth and toxicity.","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142488829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Biogenic silica dynamics in coastal wetland sediments: A key driver of silicon and carbon biogeochemical cycling","authors":"Xiangwei Zhao, Zhaoliang Song, Yuntao Wu, Lukas Van Zwieten, Laodong Guo, Changxun Yu, Zimin Li, Lele Wu, Xiaomin Yang, Xiangbin Ran, Jun Sun, Yuqiu Wei, Yidong Wang, Peng Yuan, Jianping Zhang, Xiaole Sun, Xinxin Zuo, Tony Vancov, Cong‐Qiang Liu, Hailong Wang","doi":"10.1002/lno.12717","DOIUrl":"https://doi.org/10.1002/lno.12717","url":null,"abstract":"Biogenic silica (biogenic Si) is a bioactive component crucial for the biogeochemical cycling of Si in terrestrial and aquatic ecosystems. Its formation and dissolution dynamics are intricately linked to carbon (C) cycling. However, knowledge about the source, composition, and factors controlling the distribution of biogenic Si in coastal wetland sedimentary environments is still limited. To address this lack of knowledge, we introduced a suite of geometric models for biogenic Si biovolume calculation and investigated biogenic Si assemblages, along with biogenic Si and biogenic Si‐occluded C contents, in sediments from representative coastal wetlands along the west coast of Bohai Bay. Our analysis showed that sedimentary biogenic Si predominantly derived from phytoliths (78.1% ± 5.8%), diatoms (18.2% ± 4.8%), and sponge spicules (3.7% ± 2.9%). Notably, phytolith assemblages were primarily composed of forms derived from the Poaceae family. The biogenic Si‐occluded C content (0.035–1.870 g kg<jats:sup>−1</jats:sup>) within these wetland sediments was consistent across both sites, accounting for 0.97–5.71% of the total organic C pool. Structural equation modeling indicated that total organic C, pH, and amorphous aluminum oxides either directly or indirectly influenced the biogenic Si content in coastal wetlands sediments. These results demonstrate the critical role that biogenic Si plays in the Si biogeochemical cycle and provide valuable information that advances our understanding of the biogeochemical interactions between Si and C in coastal wetland ecosystems.","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142487531","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Apparent nitrous acid dissociation across environmentally relevant temperatures in freshwater and seawater","authors":"Benedict Borer, Eric Bi, Ryan J. Woosley, Andrew R. Babbin","doi":"10.1002/lno.12714","DOIUrl":"https://doi.org/10.1002/lno.12714","url":null,"abstract":"Nitrite is a ubiquitous compound found across aquatic systems and an intermediate in both the oxidative and reductive metabolisms transforming fixed nitrogen in the environment. Yet, the abiotic cycling of nitrite is often overlooked in favor of biologically mediated reactions. Here we quantify the apparent acid dissociation constant (p<jats:italic>K</jats:italic><jats:sub>a</jats:sub>) between nitrous acid and its conjugate base nitrite in both freshwater and seawater systems across a range of environmentally relevant temperatures (5–35°C) using potentiometric‐based titration. In freshwater, we measured a p<jats:italic>K</jats:italic><jats:sub>a,NBS</jats:sub> of 3.14 at 25°C and a p<jats:italic>K</jats:italic><jats:sub>a,<jats:italic>T</jats:italic></jats:sub> of 2.87 for seawater at the same temperature. We quantify substantial effects of both salinity and temperature on the p<jats:italic>K</jats:italic><jats:sub>a</jats:sub>, with colder and fresher water manifesting higher values and thus a greater proportion of protonated nitrite at any given pH. Because nitrous acid is unstable and decomposes to nitric oxide, the implications for the nitrous acid dissociation constant on ecosystem function are broad.","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142488639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}