Global Biogeochemical Cycles最新文献_第4页

Nitrogen Biogeochemistry of Adjacent Mesoscale Eddies in the North Pacific Subtropical Gyre

IF 5.4 2区地球科学

Global Biogeochemical Cycles Pub Date : 2025-02-04 DOI: 10.1029/2024GB008206

Mengyang Zhou, Julie Granger, Cesar B. Rocha, Samantha A. Siedlecki, Benedetto Barone, Angelicque E. White

{"title":"Nitrogen Biogeochemistry of Adjacent Mesoscale Eddies in the North Pacific Subtropical Gyre","authors":"Mengyang Zhou, Julie Granger, Cesar B. Rocha, Samantha A. Siedlecki, Benedetto Barone, Angelicque E. White","doi":"10.1029/2024GB008206","DOIUrl":"https://doi.org/10.1029/2024GB008206","url":null,"abstract":"We examined the nitrogen (N) biogeochemistry of adjacent cyclonic and anticyclonic eddies near Hawai'i in the North Pacific Subtropical Gyre (NPSG) and explored mechanisms that sustain productivity in the cyclone after the initial intensification stage. The top of the nutricline was uplifted into the euphotic zone in the cyclone and depressed in the anticyclone. Subsurface nutrient concentrations and apparent oxygen utilization at the cyclone's inner periphery were higher than expected from isopycnal displacement, suggesting that shallow remineralization of organic material generated excess nutrients in the subsurface. The excess nutrients may provide a supply of subsurface nutrients to sustain productivity in maturing eddies. The shallow remineralization also raises questions regarding the extent to which cyclonic eddies promote deep carbon sequestration in subtropical gyres such as the NPSG. An upward increase in nitrate 15N/14N isotope ratios below the euphotic zone, indicative of partial nitrate assimilation, coincided with negative preformed nutrients—potentially signaling heterotrophic bacterial consumption of carbon-rich (nitrogen-poor) organic material. The 15N/14N of material collected in shallow sediment traps was significantly higher in the cyclone than in the anticyclone and showed correspondence to the 15N/14N ratio of the nitrate supply, which is acutely sensitive to sea level anomaly in the region. A number of approaches were applied to estimate the contribution of N2 fixation to export production. Results among approaches were inconsistent, which we attribute to non-steady state conditions during our observation period.","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"39 2","pages":""},"PeriodicalIF":5.4,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143111569","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}

引用次数: 0

Rainfall and Seasonality Drive Pyrogenic Carbon Stocks in Coarse-Textured Mineral Soils

IF 5.4 2区地球科学

Global Biogeochemical Cycles Pub Date : 2025-02-01 DOI: 10.1029/2024GB008240

Jordahna Haig, Sourav Das, Jonathan Sanderman, Michael I. Bird

{"title":"Rainfall and Seasonality Drive Pyrogenic Carbon Stocks in Coarse-Textured Mineral Soils","authors":"Jordahna Haig, Sourav Das, Jonathan Sanderman, Michael I. Bird","doi":"10.1029/2024GB008240","DOIUrl":"https://doi.org/10.1029/2024GB008240","url":null,"abstract":"Pyrogenic carbon (PyC) from biomass burning is a large, but poorly quantified, slow-cycling component of the soil organic carbon pool. Modeling of soil carbon dynamics can be improved by including the processes governing the input and cycling of PyC in the soil. The carbon isotope composition of PyC (δ13CPyC) provides a tracer for the partitioning of PyC into the soil from biomass. We report the stocks and δ13C values for PyC and organic carbon (OC) for 41 regions dominated by savannas and seasonally wet to arid regions of Australia and Africa. Stocks of PyC in the 0–5 cm interval ranged from 0 to 1.17 MgC ha−1 (mean 0.43 ± 0.25 MgC ha−1) and in the 0–30 cm interval ranged from 0.25 to 3.89 MgC ha−1 (mean 1.65 ± 0.77 MgC ha−1). PyC stocks averaged 8% (but were up to 25%) of total organic carbon (TOC) stocks. Stocks tended to highest in relatively wet, but seasonally dry, regions such as tropical savannas. PyC abundance could be predicted (r = 0.8 to 0.95) from environmental variables only. δ13CPyC values varied widely between regions, but with no systematic differences within regions related to current vegetation or sample depth, likely due to the long residence time of PyC in the soil. δ13CPyC values were strongly correlated with δ13COC values but were systematically 1–2‰ higher even in C3 only regions.","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"39 2","pages":""},"PeriodicalIF":5.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143110470","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}

引用次数: 0

Regional Patterns of Organic Matter Export Rates Along the GEOTRACES Pacific Meridional Transect GP15

IF 5.4 2区地球科学

Global Biogeochemical Cycles Pub Date : 2025-01-30 DOI: 10.1029/2024GB008277

Paul Quay, Mark Stephens

引用次数: 0

Using δ15N of Amino Acids and Nitrate to Investigate Particle Production and Transformation in the Ocean: A Case Study From the Eastern Tropical North Pacific Oxygen Deficient Zone

IF 5.4 2区地球科学

Global Biogeochemical Cycles Pub Date : 2025-01-11 DOI: 10.1029/2024GB008280

Charlotte Wing Man Lee, Mark Altabet, Alanna Mnich, Lin Zhang

{"title":"Using δ15N of Amino Acids and Nitrate to Investigate Particle Production and Transformation in the Ocean: A Case Study From the Eastern Tropical North Pacific Oxygen Deficient Zone","authors":"Charlotte Wing Man Lee, Mark Altabet, Alanna Mnich, Lin Zhang","doi":"10.1029/2024GB008280","DOIUrl":"https://doi.org/10.1029/2024GB008280","url":null,"abstract":"The eastern tropical North Pacific oxygen deficient zone (ETNP-ODZ) exhibits a distinct physical and biological environment compared to other oxygenated water columns, leading to a unique scenario of particulate organic matter (POM) production and vertical transport. To elucidate these biological pump processes, we present the first comparison of δ15N values of nitrate, phenylalanine (Phe), and glutamic acid (Glu) within two distinct size fractions of particles collected along a productivity gradient in the ETNP-ODZ. Low δ15NPhe and δ15NGlu values in both particle pools at sites with prominent secondary chlorophyll maximum (SCM), compared to the ambient δ15N-NO3−, suggest the presence of recycled N-utilizing primary producers distinct from those at the primary chlorophyll maximum and their contribution to export. We observed reduced 15N enrichment of Phe in small particles and a narrower δ15NPhe disparity between the two particle size fractions compared to the results from oxic waters, likely due to slower heterotrophic microbial degradation of small particles. Unique δ15NPhe and δ15NGlu signatures of particles were found at the lower oxycline, potentially attributable to chemoautotrophic production and zooplankton mediation. These findings underscore the need for further investigations targeting particles generated at the SCM, their subsequent alteration by zooplankton, and the new production by chemoautotrophs. This will allow for a better evaluation of the efficiency of the biological pump in the globally expanding ODZs under contemporary climate change.","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"39 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2025-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143114143","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}

引用次数: 0

Uncertainties About the Role of River and Mangrove Dissolved Inorganic Carbon and Alkalinity Loads in Buffering the Great Barrier Reef Lagoon

IF 5.4 2区地球科学

Global Biogeochemical Cycles Pub Date : 2025-01-07 DOI: 10.1029/2024GB008134

Judith A. Rosentreter, Bradley D. Eyre

{"title":"Uncertainties About the Role of River and Mangrove Dissolved Inorganic Carbon and Alkalinity Loads in Buffering the Great Barrier Reef Lagoon","authors":"Judith A. Rosentreter, Bradley D. Eyre","doi":"10.1029/2024GB008134","DOIUrl":"https://doi.org/10.1029/2024GB008134","url":null,"abstract":"Terrestrial dissolved inorganic carbon (DIC) and total alkalinity (TAlk) loads have contrasting effects on the pH and carbonate chemistry of the coastal ocean. While TAlk can buffer against ocean acidification, elevated exports of free CO2 can further exacerbate ocean acidification. In this study, we quantify terrestrial DIC and TAlk loads from rivers and mangrove floodplains across six bioregions and varying flow conditions to assess their impact on the buffering capacity of the Great Barrier Reef (GBR) lagoon in Australia. For a mid-flow year, median terrestrial DIC and TAlk loads ranged from 0.72 to 0.89 Tg C yr−1 and 0.26 to 1.03 Tg C yr−1, respectively. We find that mangrove-dominated terrestrial inputs only have a small influence on the whole GBR but contribute 12.5% (range: 1.9%–45.7%) of the DIC and 18.7% (range: 2.8%–68.2%) of the TAlk inner shelf inventory. Depending on the approach used to estimate TAlk loads, mangroves have a potential short-term buffering effect on near-shore coastal waters due to higher TAlk loads. However, long-term mangrove TAlk production via pyrite formation complicates this interpretation, highlighting the need for ongoing monitoring to understand the complex interplay between terrestrial inputs and their effect on the GBR carbonate chemistry.","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"39 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143112947","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}

引用次数: 0

The Contrasting Role of Marine- and Land-Terminating Glaciers on Biogeochemical Cycles in Kongsfjorden, Svalbard 斯瓦尔巴群岛Kongsfjorden海端和陆端冰川对生物地球化学循环的影响。

IF 5.4 2区地球科学

Global Biogeochemical Cycles Pub Date : 2025-01-06 DOI: 10.1029/2023GB008087

C. E. Schmidt, D. Pröfrock, G. Steinhoefel, T. Stichel, C. Mears, L. M. Wehrmann, H. Thomas

{"title":"The Contrasting Role of Marine- and Land-Terminating Glaciers on Biogeochemical Cycles in Kongsfjorden, Svalbard","authors":"C. E. Schmidt, D. Pröfrock, G. Steinhoefel, T. Stichel, C. Mears, L. M. Wehrmann, H. Thomas","doi":"10.1029/2023GB008087","DOIUrl":"10.1029/2023GB008087","url":null,"abstract":"This case study of Kongsfjorden, western coastal Svalbard, provides insights on how freshwater runoff from marine- and land-terminating glaciers influences the biogeochemical cycles and distribution patterns of carbon, nutrients, and trace elements in an Arctic fjord system. We collected samples from the water column at stations along the fjord axis and proglacial river catchments, and analyzed concentrations of dissolved trace elements, together with dissolved nutrients, as well as alkalinity and dissolved inorganic carbon. Statistical tools were applied to identify and quantify biogeochemical processes within the fjord that govern the constituent distributions. Our results suggest that the glacier type affects nutrient availability and, therefore, primary production. Glacial discharge from both marine-terminating glaciers and riverine discharge from land-terminating glaciers are important sources of dissolved trace elements (dAl, dMn, dCo, dNi, dCu, and dPb) that are involved in biological and scavenging processes within marine systems. We identified benthic fluxes across the sediment-water interface to supply fjord waters with silicate, dFe, dCu, and dZn. Our data show that intensive carbonate weathering in proglacial catchments supplies fjord waters with additional dissolved carbonates and, therefore, attenuates reduced buffering capacities caused by glacial runoff. Our study provides valuable insight into biogeochemical processes and carbon cycling within a climate-sensitive, high-latitude fjord region, which may help predict Arctic ecosystem changes in the future.","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"39 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11702319/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142946914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Particulate Cadmium Accumulation in the Mesopelagic Ocean 中远洋镉微粒累积。

IF 5.4 2区地球科学

Global Biogeochemical Cycles Pub Date : 2025-01-04 DOI: 10.1029/2024GB008281

A. Laubach, J.-M. Lee, M. Sieber, N. T. Lanning, J. N. Fitzsimmons, T. M. Conway, P. J. Lam

{"title":"Particulate Cadmium Accumulation in the Mesopelagic Ocean","authors":"A. Laubach, J.-M. Lee, M. Sieber, N. T. Lanning, J. N. Fitzsimmons, T. M. Conway, P. J. Lam","doi":"10.1029/2024GB008281","DOIUrl":"10.1029/2024GB008281","url":null,"abstract":"Observations of dissolved cadmium (dCd) and phosphate (PO4) suggest an unexplained loss of dCd to the particulate phase in tropical oxyclines. Here, we compile existing observations of particulate Cd and phosphorus (P), and present new data from the US GEOTRACES GP15 Pacific Meridional Transect to examine this phenomenon from a particulate Cd perspective. We use a simple algorithm to reproduce station depth profiles of particulate Cd and P via regeneration and possible subsurface accumulation. Our examination of regeneration reveals decoupling of particulate Cd and P driven by variable partitioning between two particulate pools with differing labilities. Further, we identify evidence for subsurface particulate Cd accumulation at 31 stations. Subsurface particulate Cd accumulation occurs most consistently in the mesopelagic tropical Pacific but can be found in all examined ocean basins. This accumulation is not well-correlated with dissolved oxygen or particulate sulfide concentration. Instead, we observe that particulate Cd accumulation occurs in regions where the concentration of dCd is relatively high compared to dissolved zinc (dZn) and speculate that it is the result of enhanced dCd biological uptake in response to the subsurface micronutrient balance.","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"39 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2025-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11699538/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142931460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Heat and Drought Events Alter Biogenic Capacity to Balance CO2 Budget in South-Western Europe 高温和干旱事件改变了欧洲西南部生物平衡二氧化碳收支的能力。

IF 5.4 2区地球科学

Global Biogeochemical Cycles Pub Date : 2025-01-03 DOI: 10.1029/2024GB008163

R. Segura-Barrero, T. Lauvaux, J. Lian, P. Ciais, A. Badia, S. Ventura, H. Bazzi, E. Abbessi, Z. Fu, J. Xiao, X. Li, G. Villalba

{"title":"Heat and Drought Events Alter Biogenic Capacity to Balance CO2 Budget in South-Western Europe","authors":"R. Segura-Barrero, T. Lauvaux, J. Lian, P. Ciais, A. Badia, S. Ventura, H. Bazzi, E. Abbessi, Z. Fu, J. Xiao, X. Li, G. Villalba","doi":"10.1029/2024GB008163","DOIUrl":"10.1029/2024GB008163","url":null,"abstract":"Heat and drought events are increasing in frequency and intensity, posing significant risks to natural and agricultural ecosystems with uncertain effects on the net ecosystem CO2 exchange (NEE). The current Vegetation Photosynthesis and Respiration Model (VPRM) was adjusted to include soil moisture impacts on the gross ecosystem exchange (GEE) and respiration (RECO) fluxes to assess the temporal variability of NEE over south-western Europe for 2001–2022. Warming temperatures lengthen growing seasons, causing an increase in GEE, which is mostly compensated by a similar increment in RECO. As a result, there is a modest increase in the net carbon sink of 0.69 gC m−2 yr−1 but with high spatial and annual variability. The heatwave of 2022 reduced net carbon uptake by 91.7 TgC, a 26.4% decrease from the mean. The interannual variability of NEE is more influenced by drought in temperate humid regions than in Mediterranean semi-arid regions. These results emphasize the vulnerability of the net carbon sink as drying trends could revert the NEE trends, as it is happening for croplands in the French Central Massif.","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"39 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11696489/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142931458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A Close Look at Dissolved Silica Dynamics in Disko Bay, West Greenland 近距离观察西格陵兰迪斯科湾溶解二氧化硅的动态。

IF 5.4 2区地球科学

Global Biogeochemical Cycles Pub Date : 2025-01-01 DOI: 10.1029/2023GB008080

Mark J. Hopwood, Dustin Carroll, Yuanyuan Gu, Xin Huang, Jana Krause, Stefano Cozzi, Carolina Cantoni, María Fernanda Gastelu Barcena, Shandy Carroll, Arne Körtzinger

{"title":"A Close Look at Dissolved Silica Dynamics in Disko Bay, West Greenland","authors":"Mark J. Hopwood, Dustin Carroll, Yuanyuan Gu, Xin Huang, Jana Krause, Stefano Cozzi, Carolina Cantoni, María Fernanda Gastelu Barcena, Shandy Carroll, Arne Körtzinger","doi":"10.1029/2023GB008080","DOIUrl":"10.1029/2023GB008080","url":null,"abstract":"Discharge of calved ice, runoff and mixing driven by subglacial discharge plumes likely have consequences for marine biogeochemistry in Disko Bay, which hosts the largest glacier in the northern hemisphere, Sermeq Kujalleq. Glacier retreat and increasing runoff may impact the marine silica cycle because glaciers deliver elevated concentrations of dissolved silica (dSi) compared to other macronutrients. However, the annual flux of dSi delivered to the ocean from the Greenland Ice Sheet is poorly constrained because of difficulties distinguishing the overlapping influence of different dSi sources. Here we constrain silica dynamics around Disko Bay, including the Ilulissat Icefjord and four other regions receiving glacier runoff with contrasting levels of productivity and turbidity. Both dissolved silica and Si* ([dSi]-[NOx−]) concentrations indicated conservative dynamics in two fjords with runoff from land-terminating glaciers, consistent with the results of mixing experiments. In three fjords with marine-terminating glaciers, macronutrient-salinity distributions were strongly affected by entrainment of nutrients in subglacial discharge plumes. Entrainment of dSi from saline waters explained 93 ± 51% of the dSi enrichment in the outflowing plume from Ilulissat Icefjord, whereas the direct contribution of freshwater to dSi in the plume was likely 0%–3%. Whilst not distinguished herein, other minor regional dSi sources include icebergs and dissolution of amorphous silica (aSi) in either pelagic or benthic environments. Our results suggest that runoff around Greenland is supplemented as a dSi source by minor fluxes of 0.25 ± 0.67 Gmol yr−1 dSi from icebergs and ∼1.9 Gmol year−1 from pelagic aSi dissolution.","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"39 1","pages":""},"PeriodicalIF":5.4,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11693982/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142931435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Dissolved Nitrogen Cycling in the Eastern Canadian Arctic Archipelago and Baffin Bay From Stable Isotopic Data 从稳定同位素数据看加拿大东部北极群岛和巴芬湾溶解氮循环。

IF 5.4 2区地球科学

Global Biogeochemical Cycles Pub Date : 2024-12-16 DOI: 10.1029/2023GB007926

H. C. Westbrook, A. Bourbonnais, C. C. M. Manning, J.-É. Tremblay, M. M. M. Ahmed, B. Else, J. Granger

{"title":"Dissolved Nitrogen Cycling in the Eastern Canadian Arctic Archipelago and Baffin Bay From Stable Isotopic Data","authors":"H. C. Westbrook, A. Bourbonnais, C. C. M. Manning, J.-É. Tremblay, M. M. M. Ahmed, B. Else, J. Granger","doi":"10.1029/2023GB007926","DOIUrl":"10.1029/2023GB007926","url":null,"abstract":"Climate change is expected to alter the input of nitrogen (N) sources in the Eastern Canadian Arctic Archipelago and Baffin Bay due to increased discharge from glacial meltwater and permafrost thaw. Since dissolved inorganic N is generally depleted in surface waters, dissolved organic N (DON) could represent a significant N source fueling phytoplankton activity in Arctic ecosystems. Yet, few DON data for this region exist. We measured concentrations and stable isotope ratios of DON (δ15N) and nitrate (NO3−; δ15N and δ18O) to investigate the sources and cycling of dissolved nitrogen in regional rivers and marine samples collected in the Eastern Canadian Arctic Archipelago and Baffin Bay during the summer of 2019. The isotopic signatures of NO3− in rivers could be reproduced in a steady state isotopic model by invoking mixing between atmospheric NO3− and nitrified ammonium as well as NO3− assimilation by phytoplankton. DON concentrations were low in most rivers (≤4.9 μmol N L−1), whereas the concentrations (0.54–12 μmol N L−1) and δ15N of DON (−0.71–9.6‰) at the sea surface were variable among stations, suggesting dynamic cycling and/or distinctive sources. In two regions with high chlorophyll-a, DON concentrations were inversely correlated with chlorophyll-a and the δ15N of DON, suggesting net DON consumption in localized phytoplankton blooms. We derived an isotope effect of 6.9‰ for DON consumption. Our data helps establish a baseline to assess future changes in the nutrient regime for this climate-sensitive region.","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"38 12","pages":""},"PeriodicalIF":5.4,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11650013/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142853583","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0