Chen, Nengwang

Maher, Damien Troy

Tamborski, Joseph James

Wang, Zhaohui Aleck

Xiao, Kai

Yu, Xuan

English

Old Dominion University

Old Dominion University ODU Digital Commons OES Faculty Publications Ocean & Earth Sciences 2022 Editorial: Advances in Understanding Lateral Blue Carbon Export From Coastal Ecosystems Kai Xiao Nengwang Chen Zhaohui Aleck Wang Joseph James Tamborski Old Dominion University, jtambors@odu.edu Damien Troy Maher See next page for additional authors Follow this and additional works at: https://digitalcommons.odu.edu/oeas_fac_pubs  Part of the Oceanography Commons, Terrestrial and Aquatic Ecology Commons, and the Water Resource Management Commons Original Publication Citation Xiao, K., Chen, N., Wang, Z. A., Tamborski, J. J., Maher, D. T., & Yu, X. (2022). Editorial: Advances in understanding lateral blue carbon export from coastal ecosystems. Frontiers in Marine Science, 9, 1-3, Article 1060958. https://doi.org/10.3389/fmars.2022.1060958 This Editorial is brought to you for free and open access by the Ocean & Earth Sciences at ODU Digital Commons. It has been accepted for inclusion in OES Faculty Publications by an authorized administrator of ODU Digital Commons. For more information, please contact digitalcommons@odu.edu. Authors Kai Xiao, Nengwang Chen, Zhaohui Aleck Wang, Joseph James Tamborski, Damien Troy Maher, and Xuan Yu This editorial is available at ODU Digital Commons: https://digitalcommons.odu.edu/oeas_fac_pubs/468 Editorial: Advances inunderstanding lateral bluecarbon export fromcoastal ecosystemsKai Xiao1, Nengwang Chen2, Zhaohui Aleck Wang3,Joseph James Tamborski4, DamienTroy Maher5 and Xuan Yu6*1State Environmental Protection Key Laboratory of Integrated SurfaceWater-Groundwater PollutionControl, School of Environmental Science and Engineering, Southern University of Science andTechnology, Shenzhen, China, 2Key Laboratory of the Coastal andWetland Ecosystems, College of theEnvironment and Ecology, Xiamen University, Xiamen, China, 3Department of Marine Chemistry andGeochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, United States, 4Department ofOcean & Earth Sciences, Old Dominion University, Norfolk, VA, United States, 5School of Environment,Science and Engineering, Southern Cross University, Lismore, NSW, Australia, 6Southern Marine Scienceand Engineering Guangdong Laboratory (Zhuhai), Zhuhai, ChinaKEYWORDSsaltmarsh, mangrove, kelp forests, groundwater, outwelling, carbon cycle, intertidalporewater, tidal flatEditorial on the Research TopicAdvances in understanding lateral blue carbon export fromcoastal ecosystems‘Blue Carbon’ refers to the carbon captured by the coastal systems or ocean and wascoined about a decade ago (Nellemann et al., 2009), emphasizing the carbonsequestration capacity of coastal vegetated ecosystems (e.g., macroalgae/kelp, seagrassbeds, saltmarshes, and mangroves). These blue carbon systems only cover <0.1% of theocean area, but may account for >50% of the carbon storage in marine environments,representing a large carbon sink comparable to the global river input (Alongi, 2014). Thefluxes of terrestrial-derived carbon including dissolved organic carbon (DOC), dissolvedinorganic carbon (DIC), and particulate organic carbon (POC) transported throughsurface river runoff to the ocean were well known and quantified (Ludwig et al., 1996;Regnier et al., 2022). However, increasing evidence suggests that tidal exchangedominates the transport of significant dissolved carbon from coastal ecosystems toadjacent estuarine and shelf waters (e.g., Maher et al., 2013; Tait et al., 2016; Wang et al.,2016; Chen et al., 2021). This mechanism is commonly named as carbon ‘outwelling’ orlateral carbon export (e.g., Teal, 1962; Odum, 1968; Wang and Cai, 2004; Sippo et al.,2017; Cabral et al., 2021; Santos et al., 2021; Tamborski et al., 2021).Outwelling represents a potentially overlooked source of ‘blue carbon’, whichmay rival or even exceed the sedimentary burial rates of blue carbon in coastalFrontiers in Marine Science frontiersin.org01OPEN ACCESSEDITED AND REVIEWED BYAngel Borja,Technology Center Expert in Marineand Food Innovation (AZTI), Spain*CORRESPONDENCEXuan Yuyuxuan7@mail.sysu.edu.cnSPECIALTY SECTIONThis article was submitted toMarine Ecosystem Ecology,a section of the journalFrontiers in Marine ScienceRECEIVED 04 October 2022ACCEPTED 21 October 2022PUBLISHED 27 October 2022CITATIONXiao K, Chen N, Wang ZA,Tamborski JJ, Maher DT and Yu X(2022) Editorial: Advances inunderstanding lateral blue carbonexport from coastal ecosystems.Front. Mar. Sci. 9:1060958.doi: 10.3389/fmars.2022.1060958COPYRIGHT© 2022 Xiao, Chen, Wang, Tamborski,Maher and Yu. This is an open-accessarticle distributed under the terms ofthe Creative Commons AttributionLicense (CC BY). The use, distributionor reproduction in other forums ispermitted, provided the originalauthor(s) and the copyright owner(s)are credited and that the originalpublication in this journal is cited, inaccordance with accepted academicpractice. No use, distribution orreproduction is permitted which doesnot comply with these terms.TYPE EditorialPUBLISHED 27 October 2022DOI 10.3389/fmars.2022.1060958frontiers I Frontiers in Marine Science ® Check for updates ecosystems (Correa et al., 2022), and yet, this pathway remainsunderstudied to date due to a lack of robust, coherentmeasurements quantifying lateral blue carbon exports in highlydynamic coastal ecosystems. The aim of this Research Topic was tosummarize the recent advances in understanding lateral bluecarbon export from coastal ecosystems. Five articles were finallycollected in this Research Topic as summarized below.Zhu et al. calculated the porewater exchange rate and fluxes ofcarbon outwelling and greenhouse gas emissions, based on a 222Rnmass balance model in a subtropical multi-species saltmarsh inHangzhou Bay, China. They found that DIC was the mostdominant (~90%) carbon species exported through outwellingand porewater exchange, which were 3.2 and 1.2 times that ofcarbon burial. The emissions of CO2 (54.6 ± 0.5 mmol m-2 d-1)and CH4 (0.19 ± 0.01 mmol m-2 d-1) from creek water can offset16% of sedimentary carbon burial. Further, the isotopic signal ofd13C and ratios of C/N reveal that the organic carbon were mainlyoriginated from the C3 plant (i.e., Scirpus mariqueter) rather thanthe C4 plant (i.e., Spartina alterniflora). This study emphasizedthat the porewater-derived carbon outwelling acts as a critical rolein the long-term carbon sink, providing a scientific basis forprotecting blue carbon ecosystems.Yuanet al. assessed the annual lateral exchangeoforganic carbonbetween the adjacent water and salt marsh at the Yangtze estuary,China, to determine whether the salt marsh acted as a net source orsink for estuarine carbon. They found that the concentrations ofDOC and POC peaked in autumn (3.54 mg L-1 and 4.19 mg L-1,respectively) anddeclined to the lowest inwinter and spring (1.87mgL-1 and 1.51 mg L-1, respectively), and their fluxes were significantlycorrelated in different seasons. In different seasons the tidal creekshowed the export of organic carbonwith the flux range from -12.65to 4.04 g C m-2. Further, the flux of organic carbon varied with tidalpattern and were significantly higher during spring tides than thatduringneap tides. Last, this study indicates that the saltmarshes actedas a net source through lateral carbon export for the estuary.Wang et al. investigated the submarine groundwater discharge(SGD) and its effect on the carbon cycle in a highly urbanized andriver-dominated coastal area, i.e., the Guangdong-HongKong-Macao Greater Bay Area in China. They found that SGD-derivedfluxes of DIC and DOC were (0.77–3.29)×1010 g d-1 and (0.60–9.94)×109 gd-1, respectively,whichwerenearly∼2 times larger thanriverine inputs. Further, they found that SGD acted as a potentialsource of atmospheric CO2 with a flux of 1.46×109 g C d-1. Theseadditional inputs of carbon andnutrientswere expected to enhancebiological pump efficiency, stimulate new primary production, andregulate the balance of the carbonate system inmarinewaters. Thisstudy emphasized that SGD is important as rivers, both of whichplays a significant role in carbon budgets at the regional andglobal scales.Kim et al. explored the spatial patterns of DIC and totalalkalinity (AlkT) productions and DIC in a shallow beach aquiferin Cape Shores, Delaware, USA. They found that the substantialchanges of DIC and AlkT can occur along the subsurfaceflowpaths due to the anoxic reactions which led to theadditional fluxes of DIC (191 mmol d-1) and AlkT (134 mmold-1) to the ocean per meter length of shoreline, respectively. Inthe saltwater-freshwater mixing zone, the ratios of DIC: AlkTand dDIC:dAlkT relative to the theoretical dilution line revealedthat both aerobic and anaerobic reactions can actively contributeto the productions of DIC and AlkT beneath the beach surface.This study suggests that the beach aquifers (as carbon-poor sites)can support the transformation of inorganic carbon and shouldnot be overlooked as an important source of DIC and AlkT likecarbon-rich mangrove wetlands.Pan et al. proposed an effective approach to track thedynamics of detached macrophytes on a semi-sheltered beach inOdense Fjord, Denmark. They conducted a monitoring surveyusing multiple technologies including real-time camera trap, deeplearning with a network architecture and partial least squaresregression analysis. The camera trap can be used as a labor-savingapproach to track the spatiotemporal dynamics of detachedmacrophytes deposited on the beach. Further, the application ofdeep learning provides an important aid in image identificationand ecological survey and environmental management.Overall, these articles presented in this Research Topicrepresent important progress, datasets, as well as novelmethodologies in understanding of lateral carbon export fromvarious coastal ecosystems (e.g., beach, salt marsh, estuary, andcoastal bay). We are convinced that this Research Topic willcontinue to inspire improvement of quantifying lateral carbonfluxes and developing effective strategies for management andprotection of the blue carbon ecosystems.Author contributionsKX invited the other guest editors NC, ZW, JT, DM and XY todesign this Research Topic. All guest editors have edited andreviewed the editorial article, and approved the submitted version.AcknowledgmentsWewould like to thank the authors for their contributions andpatience, and the reviewers for their help in the review process. KXthanks the fundings from National Natural Science Foundation ofChina (No. 41907162), GuangDong Basic and Applied BasicResearch Foundation (No. 2022A1515010572), and ShenzhenScience andTechnologyProgram(No. JSGG20210802153535002).Conflict of interestThe authors declare that the research was conducted in theabsence of any commercial or financial relationships that couldbe construed as a potential conflict of interest.Xiao et al. 10.3389/fmars.2022.1060958Frontiers in Marine Science frontiersin.org02Publisher’s noteAll claims expressed in this article are solely those of theauthors and do not necessarily represent those of their affiliatedorganizations, or those of the publisher, the editors and thereviewers. Any product that may be evaluated in this article, orclaim that may be made by its manufacturer, is not guaranteedor endorsed by the publisher.ReferencesAlongi, D. M. (2014). Carbon cycling and storage in mangrove forests. Ann. Rev.Mar. Sci. 6 (1), 195–219. doi: 10.1146/annurev-marine-010213-135020Cabral, A., Dittmar, T., Call, M., Scholten, J., de Rezende, C. E., Asp, N., et al.(2021). Carbon and alkalinity outwelling across the groundwater-creek-shelfcontinuum off Amazonian mangroves. Limnol. Oceanogr Lett. 6 (6), 369–378.doi: 10.1002/lol2.10210Chen, X., Santos, I. R., Call, M., Reithmaier, G. M. S., Maher, D., Holloway, C.,et al. (2021). The mangrove CO2 pump: Tidally driven pore-water exchange.Limnol. Oceanogr 66 (4), 1563–1577. doi: 10.1002/lno.11704Correa, R. E., Xiao, K., Conrad, S., Wadnerkar, P., Wilson, A. M., Sanders, C., et al.(2022). Groundwater carbon exports reduce the sediment carbon burial potential of asalt marsh. Estuaries Coasts 45, 1545–1561. doi: 10.1007/s12237-021-01021-1Ludwig, W., Amiotte-Suchet, P., and Probst, J. L. (1996). River discharges ofcarbon to the world’s oceans: Determining local inputs of alkalinity and ofdissolved and particulate organic carbon. Comptes Rendus l’Academie Sci. - Ser.IIa Sci. la Terre Des. Planetes 323, 1007–1014.Maher, D. T., Santos, I. R., Golsby-Smith, L., Gleeson, J., and Eyre, B. D. (2013).Groundwater-derived dissolved inorganic and organic carbon exports from amangrove tidal creek: The missing mangrove carbon sink? Limnol. Oceanogr 58(2), 475–488. doi: 10.4319/lo.2013.58.2.0475Nellemann, C., Corcoran, E., Duarte, C. M., Valdés, L., De Young, C., Fonseca,L., et al. (2009). “Blue carbon: A rapid response assessment,” Blue Carbon (Arendal,Norway: United Nations Environment Programme, GRID-Arendal).Odum, E. P. (1968). “A research challenge: Evaluating the productivity of coastaland estuarine water,” in Proceedings of the Second Sea Grant Conference (Univ. ofRhode Island) 63–64.Regnier, P., Resplandy, L., Najjar, R. G., and Ciais, P. (2022). The land-to-Oceanloops of the global carbon cycle. Nature 603, 401–410. doi: 10.1038/s41586-021-04339-9Santos, I. R., Burdige, D. J., Jennerjahn, T. C., Bouillon, S., Cabral, A., Serrano,O., et al. (2021). The renaissance of odum’s outwelling hypothesis in ‘Bluecarbon’ science. Estuar Coast. Shelf Sci. 255, 107361. doi: 10.1016/j.ecss.2021.107361Sippo, J. Z., Maher, D. T., Tait, D. R., Ruiz-Halpern, S., Sanders, C. J., and Santos,I. R. (2017). Mangrove outwelling is a significant source of oceanic exchangeableorganic carbon. Limnol. Oceanogr Lett. 2 (1), 1–8. doi: 10.1002/lol2.10031Tait, D. R., Maher, D. T., Macklin, P. A., and Santos, I. R. (2016). Mangrove porewater exchange across a latitudinal gradient. Geophys. Res. Lett. 43 (7), 3334–3341.doi: 10.1002/2016GL068289Tamborski, J. J., Eagle, M., Kurylyk, B. L., Kroeger, K. D., Wang, Z. A.,Henderson, P., et al. (2021). Pore water exchange-driven inorganic carbonexport from intertidal salt marshes. Limnol. Oceanogr. 66, 1774–1792.doi: 10.1002/lno.11721Teal, J. M. (1962). Energy-flow in salt-marsh ecosystem of Georgia. Ecology 43,614–624. doi: 10.2307/1933451Wang, Z. A., and Cai, W. J. (2004). Carbon dioxide degassing andinorganic carbon export from a marsh-dominated estuary (the duplinriver): A marsh CO2 pump. Limnol. Oceanogr. 49, 341–354. doi: 10.4319/lo.2004.49.2.0341Wang, Z. A., Kroeger, K. D., Ganju, N. K., Gonneea, M. E., and Chu, S. N.(2016). Intertidal salt marshes as an important source of inorganic carbon to thecoastal ocean. Limnol. Oceanogr. 61, 1916–1931. doi: 10.1002/lno.10347Xiao et al. 10.3389/fmars.2022.1060958Frontiers in Marine Science frontiersin.org03

Editorial: Advances in Understanding Lateral Blue Carbon Export From Coastal Ecosystems

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Editorial: Advances in Understanding Lateral Blue Carbon Export From Coastal Ecosystems

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