Journal of Geophysical Research: Biogeosciences最新文献

Peat Particulate Organic Matter Accepts Electrons During In Situ Incubation in the Anoxic Subsurface of Ombrotrophic Bogs 泥炭颗粒有机物在腐生沼泽缺氧的次表层原位孵化过程中接受电子

IF 3.7 3区环境科学与生态学

Journal of Geophysical Research: Biogeosciences Pub Date : 2024-09-13 DOI: 10.1029/2024JG008223

Nikola Obradović, Rob A. Schmitz, Frédéric Haffter, Dimitri V. Meier, Mark A. Lever, Martin H. Schroth, Michael Sander

{"title":"Peat Particulate Organic Matter Accepts Electrons During In Situ Incubation in the Anoxic Subsurface of Ombrotrophic Bogs","authors":"Nikola Obradović, Rob A. Schmitz, Frédéric Haffter, Dimitri V. Meier, Mark A. Lever, Martin H. Schroth, Michael Sander","doi":"10.1029/2024JG008223","DOIUrl":"https://doi.org/10.1029/2024JG008223","url":null,"abstract":"Peat particulate organic matter (POM) in the anoxic subsurface of peatlands is increasingly recognized as an important terminal electron acceptor (TEA) in anaerobic respiration. While POM reduction has been demonstrated in laboratory peat-soil incubations and (electro-) chemical reduction assays, direct demonstration of POM reduction in peat soils under in situ, field conditions involving quantification of transferred electrons remain missing. Herein, we demonstrate that deployment of an oxidized reference POM in the anoxic, methanogenic subsurface of three ombrotrophic bogs, followed by one year incubation, resulted in the transfer of approximately 150–170 μmol of electrons per gram POM to the deployed reference POM. The capacity of this reduced POM to accept electrons was partially restored upon subsequent exposure to dissolved oxygen. These findings provide direct evidence for POM acting as regenerable and sustainable TEA for anaerobic respiration in temporarily anoxic parts of peat soils. Based on the number of electrons transferred to POM and thermodynamic considerations, we estimate that anaerobic respiration to POM may largely suppress methanogenesis in peat soils, particularly close to the oxic-anoxic interface across which POM is expected to undergo redox cycling.","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008223","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142230997","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}

引用次数: 0

Integrating State Data Assimilation and Innovative Model Parameterization Reduces Simulated Carbon Uptake in the Arctic and Boreal Region 整合状态数据同化和创新模型参数化降低北极和北方地区的模拟碳吸收量

IF 3.7 3区环境科学与生态学

Journal of Geophysical Research: Biogeosciences Pub Date : 2024-09-13 DOI: 10.1029/2024JG008004

Xueli Huo, Andrew M. Fox, Hamid Dashti, Charles Devine, William Gallery, William K. Smith, Brett Raczka, Jeffrey L. Anderson, Alistair Rogers, David J. P. Moore

{"title":"Integrating State Data Assimilation and Innovative Model Parameterization Reduces Simulated Carbon Uptake in the Arctic and Boreal Region","authors":"Xueli Huo, Andrew M. Fox, Hamid Dashti, Charles Devine, William Gallery, William K. Smith, Brett Raczka, Jeffrey L. Anderson, Alistair Rogers, David J. P. Moore","doi":"10.1029/2024JG008004","DOIUrl":"https://doi.org/10.1029/2024JG008004","url":null,"abstract":"Model representation of carbon uptake and storage is essential for accurate projection of the response of the arctic-boreal zone to a rapidly changing climate. Land model estimates of LAI and aboveground biomass that can have a marked influence on model projections of carbon uptake and storage vary substantially in the arctic and boreal zone, making it challenging to correctly evaluate model estimates of Gross Primary Productivity (GPP). To understand and correct bias of LAI and aboveground biomass in the Community Land Model (CLM), we assimilated the 8-day Moderate Resolution Imaging Spectroradiometer (MODIS) LAI observation and a machine learning product of annual aboveground biomass into CLM using an Ensemble Adjustment Kalman Filter (EAKF) in an experimental region including Alaska and Western Canada. Assimilating LAI and aboveground biomass reduced these model estimates by 58% and 72%, respectively. The change of aboveground biomass was consistent with independent estimates of canopy top height at both regional and site levels. The International Land Model Benchmarking system assessment showed that data assimilation significantly improved CLM's performance in simulating the carbon and hydrological cycles, as well as in representing the functional relationships between LAI and other variables. To further reduce the remaining bias in GPP after LAI bias correction, we re-parameterized CLM to account for low temperature suppression of photosynthesis. The LAI bias corrected model that included the new parameterization showed the best agreement with model benchmarks. Combining data assimilation with model parameterization provides a useful framework to assess photosynthetic processes in LSMs.","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142230996","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Quantifying Relative Contribution of Submerged Macrophytes to Sedimentary Organic Matter Using Concentrations and δ13C of n-Alkanes With the Bayesian Multi-Source Mixing Model: A Case Study From the Yangtze Floodplain 利用贝叶斯多源混合模型，利用正烷烃的浓度和δ13C量化沉积有机质中沉水植物的相对贡献：长江冲积平原案例研究

IF 3.7 3区环境科学与生态学

Journal of Geophysical Research: Biogeosciences Pub Date : 2024-09-12 DOI: 10.1029/2024JG008159

Linghan Zeng, Xianyu Huang, Deming Yang, Guang Yang, Yiming Zhang, Xu Chen

{"title":"Quantifying Relative Contribution of Submerged Macrophytes to Sedimentary Organic Matter Using Concentrations and δ13C of n-Alkanes With the Bayesian Multi-Source Mixing Model: A Case Study From the Yangtze Floodplain","authors":"Linghan Zeng, Xianyu Huang, Deming Yang, Guang Yang, Yiming Zhang, Xu Chen","doi":"10.1029/2024JG008159","DOIUrl":"https://doi.org/10.1029/2024JG008159","url":null,"abstract":"Submerged macrophytes are important indicators of the state of shallow freshwater ecosystems. Reconstruction long-term changes in submerged macrophytes remains a challenge in paleoecology. Here, the relative biomass (mass weight) of different plants to sedimentary organic matter in a shallow lake in central China was estimated using a Bayesian multi-source mixing model with concentrations and δ13C of n-alkanes extracted from surface lake sediments. The spatial distribution of submerged macrophytes biomass estimated by the model correlates with water transparency, water depth, and total nitrogen. The correlation patterns are consistent with previously established patterns of submerged macrophyte growth and water conditions, which supports the utility of the Bayesian approach in shallow freshwater lakes. In comparison, Paq, proportion of mid-chain length (C23, C25) to long-chain length (C29, C31) homologs, underestimated the contribution of submerged macrophytes, especially in samples with moderate Paq values (0.3 < Paq < 0.4). On the other hand, some discrepancies between the model output and the satellite imagery estimated macrophyte coverage are present, which suggests that ground-truthing is needed to further evaluate this approach. Our study demonstrates that the Bayesian mixing model combining the abundance and isotopes of n-alkanes makes a reasonable estimation of the relative biomass of submerged macrophytes in the sediments. This approach provides new insights into reconstructing long-term variations in submerged macrophytes for paleoecological studies, which is valuable for the restoration and conservation of shallow freshwater lakes when long-term limnological monitoring is lacking.","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142174226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Imaging Spectroscopy-Based Estimation of Aboveground Biomass in Louisiana's Coastal Wetlands: Toward Consistent Spectroscopic Retrievals Across Atmospheric States 基于成像光谱的路易斯安那州沿海湿地地上生物量估算：实现大气状态下光谱检索的一致性

IF 3.7 3区环境科学与生态学

Journal of Geophysical Research: Biogeosciences Pub Date : 2024-09-09 DOI: 10.1029/2024JG008112

Daniel Jensen, David R. Thompson, Marc Simard, Elena Solohin, Edward Castañeda-Moya

{"title":"Imaging Spectroscopy-Based Estimation of Aboveground Biomass in Louisiana's Coastal Wetlands: Toward Consistent Spectroscopic Retrievals Across Atmospheric States","authors":"Daniel Jensen, David R. Thompson, Marc Simard, Elena Solohin, Edward Castañeda-Moya","doi":"10.1029/2024JG008112","DOIUrl":"https://doi.org/10.1029/2024JG008112","url":null,"abstract":"Developing accurate landscape-scale aboveground biomass (AGB) maps is critical to understanding coastal deltaic wetland resilience, as AGB influences stability and elevation dynamics in herbaceous wetlands. Here we used AVIRIS-NG imaging spectrometer (or “hyperspectral”) data from NASA's 2021 Delta-X mission in coastal Louisiana to map seasonal changes in herbaceous AGB across two deltaic basins with contrasting sediment delivery and hydrologic regimes: the Atchafalaya (active) and Terrebonne (inactive). We assessed the impact of atmospheric effects on our retrievals, as high water vapor content in August 2021 caused significant noise in the 880–1,000 and 1,080–1,200 nm near-infrared (NIR) wavelengths. We hypothesized that correcting these wavelengths with our conditional Gaussian interpolation algorithm would improve AGB estimates due to their association with plant canopy water content. We empirically assessed the performance of the corrected spectra on AGB estimates using Partial Least Squares Regression (PLSR), finding that the corrected NIR bands attained high variable importance and reduced estimation errors. Our Random Forest regression approach based on the corrected spectra attained equivalent error metrics via leave-one-out-cross-validation as the PLSR models (R2 = 0.43, mean absolute error = 257.3 g/m2) while greatly improving the AGB maps' visual quality, having better captured variability while reducing noise and discontinuities in AGB estimates across flightlines. The maps show differing seasonal growth, with the Atchafalaya and Terrebonne Basins' AGB increasing from means of 4.3–9.4 and 4.6–8.9 Mg/ha, respectively. We demonstrated that imaging spectroscopy can be applied to assess herbaceous biomass stocks, growth patterns, and resilience in coastal ecosystems.","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008112","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142165601","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}

引用次数: 0

Evidence for Wildland Fire Smoke Transport of Microbes From Terrestrial Sources to the Atmosphere and Back 野地火灾烟雾将微生物从陆地源传输到大气层并返回的证据

IF 3.7 3区环境科学与生态学

Journal of Geophysical Research: Biogeosciences Pub Date : 2024-09-09 DOI: 10.1029/2024JG008236

Krista Bonfantine, David C. Vuono, Brent C. Christner, Rachel Moore, Sam Fox, Timothy Dean, Doris Betancourt, Adam Watts, Leda N. Kobziar

{"title":"Evidence for Wildland Fire Smoke Transport of Microbes From Terrestrial Sources to the Atmosphere and Back","authors":"Krista Bonfantine, David C. Vuono, Brent C. Christner, Rachel Moore, Sam Fox, Timothy Dean, Doris Betancourt, Adam Watts, Leda N. Kobziar","doi":"10.1029/2024JG008236","DOIUrl":"https://doi.org/10.1029/2024JG008236","url":null,"abstract":"Smoke from wildland fires contains more diverse, viable microbes than typical ambient air, yet little is known about the sources and sinks of smoke-borne microorganisms. Data from molecular-based surveys suggest that smoke-borne microorganisms originate from material associated with the vegetation and underlying soils that becomes aerosolized during combustion, however, the sources of microbes in smoke have not yet been experimentally assessed. To elucidate this link, we studied high-intensity forest fires in the Fishlake National Forest, Utah, USA and applied source-sink modeling to assemblages of 16S ribosomal RNA (rRNA) gene sequences recovered from samples of smoke, vegetation, and soil. Our results suggest that 70% of the bacterial taxa in smoke originated from the local aspen (Populus tremuloides) (33%) and soil (37%) communities. In comparison, 42% of bacteria in air sampled prior to the fires could be attributed to these terrestrial sources. When the bacterial assemblages in smoke were modeled as sources to the local communities, they contributed an average of 25% to the terrestrial sinks versus an estimated contribution of <4% from ambient air. Our results provide support for the role of wildland fire in bacterial dispersal and the working hypothesis that smoke is an environmental reservoir of microbes for receiving ecosystems.","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142165599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Divergent Responses of Fir and Pine Trees to Increasing CO2 Levels in the Face of Climate Change 面对气候变化，杉树和松树对二氧化碳含量增加的不同反应

IF 3.7 3区环境科学与生态学

Journal of Geophysical Research: Biogeosciences Pub Date : 2024-09-09 DOI: 10.1029/2023JG007754

A. Correa-Díaz, A. Gómez-Guerrero, L. U. Castruita-Esparza, L. C. R. Silva, W. R. Horwath

{"title":"Divergent Responses of Fir and Pine Trees to Increasing CO2 Levels in the Face of Climate Change","authors":"A. Correa-Díaz, A. Gómez-Guerrero, L. U. Castruita-Esparza, L. C. R. Silva, W. R. Horwath","doi":"10.1029/2023JG007754","DOIUrl":"https://doi.org/10.1029/2023JG007754","url":null,"abstract":"Understanding the response of forests to the increases in atmospheric CO2 (ca) is fundamental to implementing innovative management strategies and for assessing impacts on the global carbon and water cycles. Here, we explored correlations between ecophysiological traits and climate variability that influence changes in stable isotope carbon and oxygen (δ13C and δ18O) of tree-rings. We present these relationships between species of the contrasting genera Abies and Pinus, along a latitudinal transect encompassing different biogeographical regions in North America. We also tested if the rate of intrinsic water-use efficiency per unit of ca (dW/dca) during two periods (1890–1965 vs. 1966–2016), for fir and pine were different and indicated acclimation to ca increases. We hypothesize that, spatially and temporally, the divergent responses among species to carbon and oxygen isotopes and dW/dca are influenced by the site conditions and the historical increases in ca. From our results, we show that fir and pine species will behave physiologically different as global warming progresses. Firs are more responsive to atmosphere vapor pressure deficit along different geographical zones. The survival of forests species under climate change will rely on the response to water stress and species' traits that influence the regulation of dW. Finally, we want to highlight the concept of “progressive resource limitation” of soil water and nutrients, previously proposed by other authors, that likely indicate fir species that inhabit moister sites will benefit more from increased ca than pine, but this positive effect is likely transitory as global warming increases.","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142165598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

On the Variability of Phytoplankton Photophysiology Along a Latitudinal Transect in the North Atlantic Surface Ocean 关于北大西洋表层海洋纬向横断面浮游植物光生理学的变异性

IF 3.7 3区环境科学与生态学

Journal of Geophysical Research: Biogeosciences Pub Date : 2024-09-04 DOI: 10.1029/2023JG007962

Hedy M. Aardema, Hans A. Slagter, Isabella Hrabe de Angelis, Maria Ll. Calleja, Antonis Dragoneas, Simone Moretti, Nina Schuback, Lena Heins, David Walter, Ulrike Weis, Gerald H. Haug, Ralf Schiebel

{"title":"On the Variability of Phytoplankton Photophysiology Along a Latitudinal Transect in the North Atlantic Surface Ocean","authors":"Hedy M. Aardema, Hans A. Slagter, Isabella Hrabe de Angelis, Maria Ll. Calleja, Antonis Dragoneas, Simone Moretti, Nina Schuback, Lena Heins, David Walter, Ulrike Weis, Gerald H. Haug, Ralf Schiebel","doi":"10.1029/2023JG007962","DOIUrl":"https://doi.org/10.1029/2023JG007962","url":null,"abstract":"Phytoplankton photosynthesis is the first step of energy capture in the open ocean and is therefore fundamental for global biogeochemical processes and ecosystem functioning. High-resolution methods are required to fully capture the variability of marine photosynthesis and its environmental drivers. Here, we combine two high-resolution underway methods to study phytoplankton photophysiology, Fast Repetition Rate fluorometry and Flow Cytometry, along a transect in the North-East Atlantic Ocean from the polar circle to the equator. Significant spatial distinctions in photophysiological strategies were found between biogeographical provinces. The most pronounced distinction was present between the subarctic North Atlantic and the oligotrophic subtropical gyre, where the latter was typified by high photosystem II (PSII) turnover rates, low pigment-to-cell volume ratios, low PSII quantum efficiency and low absorption cross sections for photochemistry in PSII. Small-scale variability along the transect results from varying diel cycles in photophysiology, possibly governed by light availability and cell metabolism. In general, we found that variability in PSII photochemistry was associated with variability in sea surface temperature, whereas the median mixed layer irradiance could explain more of the variation in the light harvesting capacity of the phytoplankton community. This implies that the expected climate change driven shoaling of the mixed layer may impact phytoplankton light harvesting strategies.","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023JG007962","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142137744","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}

引用次数: 0

Classifying Plant Communities in the North American Coastal Plain With PRISMA Spaceborne Hyperspectral Imagery and the Spectral Mixture Residual 利用 PRISMA 星载高光谱成像和光谱混合残差对北美沿海平原的植物群落进行分类

IF 3.7 3区环境科学与生态学

Journal of Geophysical Research: Biogeosciences Pub Date : 2024-09-03 DOI: 10.1029/2024JG008217

Jennifer A. Rogers, Kevin M. Robertson, Todd J. Hawbaker, Daniel J. Sousa

{"title":"Classifying Plant Communities in the North American Coastal Plain With PRISMA Spaceborne Hyperspectral Imagery and the Spectral Mixture Residual","authors":"Jennifer A. Rogers, Kevin M. Robertson, Todd J. Hawbaker, Daniel J. Sousa","doi":"10.1029/2024JG008217","DOIUrl":"https://doi.org/10.1029/2024JG008217","url":null,"abstract":"The effort to map terrestrial biodiversity, in recent years limited mostly to the use of broadband multispectral remote sensing at decameter scales, can be greatly enhanced by harnessing hyperspectral imagery. Interpretation of hyperspectral imagery may be aided by the Mixture Residual (MR) spectral preprocessing transformation. MR integrates the benefits of spectral mixture analysis with the absorption peak-enhancing characteristics of continuum removal. MR characterizes each pixel as a linear combination of generic end-members estimating the spectral continuum, from which the residual of each wavelength is computed and treated as a source of additional information. Using Hyperspectral Precursor of the Application Mission (PRISMA) imagery, we tested the ability of MR-transformed reflectance as compared to untransformed surface reflectance (SR) to map plant associations and land cover using ground truthing and random forest classifications across four landscapes within the North American Coastal Plain. We used a forward stepwise selection algorithm to choose bands for each classification and subsequently compared these between SR and MR. Our MR classifications distinguished land cover with 5% greater balanced accuracy on average than the SR-based classifications across all four landscapes. The MR-based classification that integrated data from all landscapes into a unified model encompassing all 21 land cover types achieved a 76% average balanced accuracy over three iterations. Generally, MR utilized the near-infrared region to a greater degree than SR while deemphasizing the green peak. Based on our results, MR improves the accuracy of mapping terrestrial biodiversity, likely extending to other current and planned satellite hyperspectral missions.","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008217","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142130387","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}

引用次数: 0

Beyond Hydrology: Exploring the Factors Influencing the Seasonal Variation of the Molecular Composition of Riverine Dissolved Organic Matter 超越水文学：探索影响河流溶解有机物分子组成季节性变化的因素

IF 3.7 3区环境科学与生态学

Journal of Geophysical Research: Biogeosciences Pub Date : 2024-09-02 DOI: 10.1029/2024JG008014

Xiaoqian Zhan, Hongyan Bao, Jutta Niggemann, Weiqiang Zhao, Nengwang Chen, Dekun Huang, Moge Du, Yuanbi Yi, Thorsten Dittmar, Shuh-Ji Kao

{"title":"Beyond Hydrology: Exploring the Factors Influencing the Seasonal Variation of the Molecular Composition of Riverine Dissolved Organic Matter","authors":"Xiaoqian Zhan, Hongyan Bao, Jutta Niggemann, Weiqiang Zhao, Nengwang Chen, Dekun Huang, Moge Du, Yuanbi Yi, Thorsten Dittmar, Shuh-Ji Kao","doi":"10.1029/2024JG008014","DOIUrl":"https://doi.org/10.1029/2024JG008014","url":null,"abstract":"The export of dissolved organic matter (DOM) from rivers is essential for linking terrestrial and marine carbon reservoirs in the global carbon cycle. However, there is limited knowledge regarding how the molecular composition of riverine DOM changes under different hydrological conditions, especially during extreme rainfall events. Moreover, the factors beyond hydrology that impact DOM composition have not been well defined. To address these gaps, samples were collected from a human-impacted medium-sized subtropical monsoonal river across various hydrological conditions throughout a complete hydrological cycle. Utilizing high-resolution mass spectrometry, it was discovered that the solid-phase extractable DOM (SPE-DOM) during the high-flow (1 < runoff (Q): annual mean runoff (Qm) < 3) and extreme-rain (Q:Qm > 3) periods exhibited a higher number of molecular formulae, lower H/C, higher O/C, and a higher proportion of carboxylic-rich alicyclic molecules compared to the low-flow period (LFP) (Q:Qm < 1). These alterations were attributed to input from more diverse sources, particularly a greater input from soil organic matter with higher oxidation degrees. Additionally, the P-containing formulae were more enriched during the extreme-rain period, likely from agricultural lands and sediment release. Conversely, the fraction of S-containing formulae was significantly higher during the LFP, possibly due to the amplified influence of anthropogenic input. Furthermore, the DOM aromaticity did not fluctuate with runoff but was significantly associated with temperature. In summary, the study indicated that the composition of DOM varied significantly under different hydrological conditions, with temperature and anthropogenic activities identified as crucial factors influencing riverine DOM export.","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142123279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A New Method for the Detection of Siliceous Microfossils on Sediment Microscope Slides Using Convolutional Neural Networks 利用卷积神经网络检测沉积物显微切片上硅质微化石的新方法

IF 3.7 3区环境科学与生态学

Journal of Geophysical Research: Biogeosciences Pub Date : 2024-09-01 DOI: 10.1029/2024JG008047

Camille Godbillot, Ross Marchant, Luc Beaufort, Karine Leblanc, Yves Gally, Thang D. Q. Le, Cristele Chevalier, Thibault de Garidel-Thoron

{"title":"A New Method for the Detection of Siliceous Microfossils on Sediment Microscope Slides Using Convolutional Neural Networks","authors":"Camille Godbillot, Ross Marchant, Luc Beaufort, Karine Leblanc, Yves Gally, Thang D. Q. Le, Cristele Chevalier, Thibault de Garidel-Thoron","doi":"10.1029/2024JG008047","DOIUrl":"https://doi.org/10.1029/2024JG008047","url":null,"abstract":"Diatom communities preserved in sediment samples are valuable indicators for understanding the past and present dynamics of phytoplankton communities, and their response to environmental changes. These studies are traditionally achieved by counting methods using optical microscopy, a time-consuming process that requires taxonomic expertise. With the advent of automated image acquisition workflows, large image data sets can now be acquired, but require efficient preprocessing methods. Detecting diatom frustules on microscope images is a challenge due to their low relief, diverse shapes, and tendency to aggregate, which prevent the use of traditional thresholding techniques. Deep learning algorithms have the potential to resolve these challenges, more particularly for the task of object detection. Here we explore the use of a Faster Region-based Convolutional Neural Network model to detect siliceous biominerals, including diatoms, in microscope images of a sediment trap series from the Mediterranean Sea. Our workflow demonstrates promising results, achieving a precision score of 0.72 and a recall score of 0.74 when applied to a test set of Mediterranean diatom images. Our model performance decreases when used to detect fragments of these microfossils; it also decreases when particles are aggregated or when images are out of focus. Microfossil detection remains high when the model is used on a microscope image set of sediments from a different oceanic basin, demonstrating its potential for application in a wide range of contemporary and paleoenvironmental studies. This automated method provides a valuable tool for analyzing complex samples, particularly for rare species under-represented in training data sets.","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008047","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142123317","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}

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