Chesapeake Bay acidification buffered by spatially decoupled carbonate mineral cycling


Uptake of anthropogenic carbon dioxide (CO2) from the atmosphere has acidified the ocean and threatened the health of marine organisms and their ecosystems. In coastal waters, acidification is often enhanced by CO2 and acids produced under high rates of biological respiration. However, less is known about buffering processes that counter coastal acidification in eutrophic and seasonally hypoxic water bodies, such as the Chesapeake Bay. Here, we use carbonate chemistry, mineralogical analyses and geochemical modelling to demonstrate the occurrence of a bay-wide pH-buffering mechanism resulting from spatially decoupled calcium carbonate mineral cycling. In summer, high rates of photosynthesis by dense submerged aquatic vegetation at the head of the bay and in shallow, nearshore areas generate high pH, an elevated carbonate mineral saturation state and net alkalinity uptake. Calcium carbonate particles produced under these conditions are subsequently transported downstream into corrosive subsurface waters, where their dissolution buffers pH decreases caused by aerobic respiration and anthropogenic CO2. Because this pH-buffering mechanism would be strengthened by further nutrient load reductions and associated submerged aquatic vegetation recovery, our findings suggest that the reduction of nutrient inputs into coastal waters will not only reduce eutrophication and hypoxia, but also alleviate the severity of coastal ocean acidification.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Distributions of water properties in the Chesapeake Bay in August 2016.
Fig. 2: Non-conservative carbonate system behaviour.
Fig. 3: Water chemistry and calcium carbonate precipitation in Susquehanna Flats SAV beds.
Fig. 4: Differential effects on pH from biogeochemical processes in the Chesapeake Bay.
Fig. 5: Conceptual model of the self-regulated pH-buffering mechanism in the Chesapeake Bay.

Data availability

The data presented in this study can be found in the NCEI Ocean Archive with accession number 0209358. Source data are provided with this paper.


  1. 1.

    Gattuso, J.-P. et al. Contrasting futures for ocean and society from different anthropogenic CO2 emissions scenarios. Science 349, aac4722 (2015).

    Article  Google Scholar 

  2. 2.

    Feely, R. A. et al. The combined effects of acidification and hypoxia on pH and aragonite saturation in the coastal waters of the California current ecosystem and the northern Gulf of Mexico. Cont. Shelf Res. 152, 50–60 (2018).

    Article  Google Scholar 

  3. 3.

    Fabry, V. J., Seibel, B. A., Feely, R. A. & Orr, J. C. Impacts of ocean acidification on marine fauna and ecosystem processes. ICES J. Mar. Sci. 65, 414–432 (2008).

    Article  Google Scholar 

  4. 4.

    Cai, W.-J. et al. Acidification of subsurface coastal waters enhanced by eutrophication. Nat. Geosci. 4, 766–770 (2011).

    Article  Google Scholar 

  5. 5.

    Wallace, R. B., Baumann, H., Grear, J. S., Aller, R. C. & Gobler, C. J. Coastal ocean acidification: the other eutrophication problem. Estuar. Coast. Shelf Sci. 148, 1–13 (2014).

    Article  Google Scholar 

  6. 6.

    Andersson, A. J., Mackenzie, F. T. & Lerman, A. Coastal ocean and carbonate systems in the high CO2 world of the Anthropocene. Am. J. Sci. 305, 875–918 (2005).

    Article  Google Scholar 

  7. 7.

    Macreadie, P. I., Serrano, O., Maher, D. T., Duarte, C. M. & Beardall, J. Addressing calcium carbonate cycling in blue carbon accounting. Limnol. Oceanogr. Lett. 2, 195–201 (2017).

    Article  Google Scholar 

  8. 8.

    Cai, W.-J. et al. Redox reactions and weak buffering capacity lead to acidification in the Chesapeake Bay. Nat. Commun. 8, 369 (2017).

    Article  Google Scholar 

  9. 9.

    Green, M. A., Waldbusser, G. G., Reilly, S. L., Emerson, K. & O’Donnell, S. Death by dissolution: sediment saturation state as a mortality factor for juvenile bivalves. Limnol. Oceanogr. 54, 1037–1047 (2009).

    Article  Google Scholar 

  10. 10.

    Abril, G., Etcheber, H., Delille, B., Frankignoulle, M. & Borges, A. V. Carbonate dissolution in the turbid and eutrophic Loire estuary. Mar. Ecol. Prog. Ser. 259, 129–138 (2003).

    Article  Google Scholar 

  11. 11.

    Waldbusser, G. G., Powell, E. N. & Mann, R. Ecosystem effects of shell aggregations and cycling in coastal waters: an example of Chesapeake Bay oyster reefs. Ecology 94, 895–903 (2013).

    Article  Google Scholar 

  12. 12.

    Ware, J. R., Smith, S. V. & Reaka-Kudla, M. L. Coral reefs: sources or sinks of atmospheric CO2? Coral Reefs 11, 127–130 (1992).

    Article  Google Scholar 

  13. 13.

    Borowitzka, M. A. & Larkum, A. W. D. Calcification in algae: mechanisms and the role of metabolism. Crit. Rev. Plant Sci. 6, 1–45 (1987).

    Article  Google Scholar 

  14. 14.

    Chauvaud, L., Thompson, J. K., Cloern, J. E. & Thouzeau, G. Clams as CO2 generators: the Potamocorbula amurensis example in San Francisco Bay. Limnol. Oceanogr. 48, 2086–2092 (2003).

    Article  Google Scholar 

  15. 15.

    Warren, L. A., Maurice, P. A., Parmar, N. & Ferris, F. G. Microbially mediated calcium carbonate precipitation: implications for interpreting calcite precipitation and for solid-phase capture of inorganic contaminants. Geomicrobiol. J. 18, 93–115 (2001).

    Article  Google Scholar 

  16. 16.

    Perry, C. T. et al. Fish as major carbonate mud producers and missing components of the tropical carbonate factory. Proc. Natl Acad. Sci. USA 108, 3865–3869 (2011).

    Article  Google Scholar 

  17. 17.

    Borowitzka, M. A. Calcification in aquatic plants. Plant Cell Environ. 7, 457–466 (1984).

    Article  Google Scholar 

  18. 18.

    Mazarrasa, I. et al. Seagrass meadows as a globally significant carbonate reservoir. Biogeosciences 12, 4993–5003 (2015).

    Article  Google Scholar 

  19. 19.

    Enríquez, S. & Schubert, N. Direct contribution of the seagrass Thalassia testudinum to lime mud production. Nat. Commun. 5, 3835 (2014).

    Article  Google Scholar 

  20. 20.

    Corlett, H. & Jones, B. Epiphyte communities on Thalassia testudinum from Grand Cayman, British West Indies: their composition, structure, and contribution to lagoonal sediments. Sediment. Geol. 194, 245–262 (2007).

    Article  Google Scholar 

  21. 21.

    Koch, E. W. Sediment resuspension in a shallow Thalassia testudinum banks ex König bed. Aquat. Bot. 65, 269–280 (1999).

    Article  Google Scholar 

  22. 22.

    Orth, R. J. & Moore, K. A. Chesapeake Bay: an unprecedented decline in submerged aquatic vegetation. Science 222, 51–53 (1983).

    Article  Google Scholar 

  23. 23.

    Orth, R. J. et al. Long-term trends in submersed aquatic vegetation (SAV) in Chesapeake Bay, USA, related to water quality. Estuaries Coasts 33, 1144–1163 (2010).

    Article  Google Scholar 

  24. 24.

    Orth, R. J., Batiuk, R. A., Bergstrom, P. W. & Moore, K. A. A perspective on two decades of policies and regulations influencing the protection and restoration of submerged aquatic vegetation in Chesapeake Bay, USA. Bull. Mar. Sci. 71, 1391–1403 (2002).

    Google Scholar 

  25. 25.

    Lefcheck, J. S. et al. Long-term nutrient reductions lead to the unprecedented recovery of a temperate coastal region. Proc. Natl Acad. Sci. USA 115, 3658–3662 (2018).

    Article  Google Scholar 

  26. 26.

    Kemp, W. et al. Eutrophication of Chesapeake Bay: historical trends and ecological interactions. Mar. Ecol. Prog. Ser. 303, 1–29 (2005).

    Article  Google Scholar 

  27. 27.

    Murphy, R. R., Kemp, W. M. & Ball, W. P. Long-term trends in Chesapeake Bay seasonal hypoxia, stratification, and nutrient loading. Estuaries Coasts 34, 1293–1309 (2011).

    Article  Google Scholar 

  28. 28.

    Su, J. et al. Source partitioning of oxygen-consuming organic matter in the hypoxic zone of the Chesapeake Bay. Limnol. Oceanogr. (2020).

  29. 29.

    Gurbisz, C. & Kemp, W. M. Unexpected resurgence of a large submersed plant bed in Chesapeake Bay: analysis of time series data. Limnol. Oceanogr. 59, 482–494 (2014).

    Article  Google Scholar 

  30. 30.

    Waldbusser, G. G., Steenson, R. A. & Green, M. A. Oyster shell dissolution rates in estuarine waters: effects of pH and shell legacy. J. Shellfish Res. 30, 659–669 (2011).

    Article  Google Scholar 

  31. 31.

    Waldbusser, G. G., Voigt, E. P., Bergschneider, H., Green, M. A. & Newell, R. I. E. Biocalcification in the eastern oyster (Crassostrea virginica) in relation to long-term trends in Chesapeake Bay pH. Estuaries Coasts 34, 221–231 (2011).

    Article  Google Scholar 

  32. 32.

    Schulte, D. M. History of the Virginia oyster fishery, Chesapeake Bay, USA. Front. Mar. Sci. 4, 127 (2017).

    Article  Google Scholar 

  33. 33.

    Officer, C. B. in Estuarine and Wetland Processes: With Emphasis on Modeling (eds Hamilton, P. & Macdonald, K. B.) 65–114 (Springer, 1980).

  34. 34.

    Beer, D. D. & Larkum, A. W. D. Photosynthesis and calcification in the calcifying algae Halimeda discoidea studied with microsensors. Plant Cell Environ. 24, 1209–1217 (2001).

    Article  Google Scholar 

  35. 35.

    Semesi, I. S., Beer, S. & Björk, M. Seagrass photosynthesis controls rates of calcification and photosynthesis of calcareous macroalgae in a tropical seagrass meadow. Mar. Ecol. Prog. Ser. 382, 41–47 (2009).

    Article  Google Scholar 

  36. 36.

    Koch, E. W. Hydrodynamics, diffusion-boundary layers and photosynthesis of the seagrasses Thalassia testudinum and Cymodocea nodosa. Mar. Biol. 118, 767–776 (1994).

    Article  Google Scholar 

  37. 37.

    Du, J. & Shen, J. Water residence time in Chesapeake Bay for 1980–2012. J. Mar. Syst. 164, 101–111 (2016).

    Article  Google Scholar 

  38. 38.

    Officer, C. B. Discussion of the behaviour of nonconservative dissolved constituents in estuaries. Estuar. Coast. Mar. Sci. 9, 91–94 (1979).

    Article  Google Scholar 

  39. 39.

    Cai, W.-J., Wiebe, W. J., Wang, Y. & Sheldon, J. E. Intertidal marsh as a source of dissolved inorganic carbon and a sink of nitrate in the Satilla River–estuarine complex in the southeastern U.S. Limnol. Oceanogr. 45, 1743–1752 (2000).

    Article  Google Scholar 

  40. 40.

    Heck, K. L. & Orth, R. J. Structural components of eelgrass (Zostera marina) meadows in the lower Chesapeake Bay—decapod crustacea. Estuaries 3, 289–295 (1980).

    Article  Google Scholar 

  41. 41.

    Karlsen, A. W. et al. Historical trends in Chesapeake Bay dissolved oxygen based on benthic foraminifera from sediment cores. Estuaries 23, 488–508 (2000).

    Article  Google Scholar 

  42. 42.

    Kemp, W. M., Smith, E. M., Marvin-DiPasquale, M. & Boynton, W. R. Organic carbon balance and net ecosystem metabolism in Chesapeake Bay. Mar. Ecol. Prog. Ser. 150, 229–248 (1997).

    Article  Google Scholar 

  43. 43.

    Malone, T. C. et al. Lateral variation in the production and fate of phytoplankton in a partially stratified estuary. Mar. Ecol. Prog. Ser. 32, 149–160 (1986).

    Article  Google Scholar 

  44. 44.

    Valle-Levinson, A. & Lwiza, K. M. M. The effects of channels and shoals on exchange between the Chesapeake Bay and the adjacent ocean. J. Geophys. Res. Oceans 100, 18551–18563 (1995).

    Article  Google Scholar 

  45. 45.

    Fugate, D. C., Friedrichs, C. T. & Sanford, L. P. Lateral dynamics and associated transport of sediment in the upper reaches of a partially mixed estuary, Chesapeake Bay, USA. Cont. Shelf Res. 27, 679–698 (2007).

    Article  Google Scholar 

  46. 46.

    Saderne, V. et al. Role of carbonate burial in Blue Carbon budgets. Nat. Commun. 10, 1106 (2019).

    Article  Google Scholar 

  47. 47.

    Gruber, R. K. & Kemp, W. M. Feedback effects in a coastal canopy-forming submersed plant bed. Limnol. Oceanogr. 55, 2285–2298 (2010).

    Article  Google Scholar 

  48. 48.

    Cafrey, J. M. & Kemp, W. M. Influence of the submersed plant, Potamogeton perfoliatus, on nitrogen cycling in estuarine sediments. Limnol. Oceanogr. 37, 1483–1495 (1992).

    Article  Google Scholar 

  49. 49.

    Gurbisz, C. et al. Interactive effects of physical and biogeochemical feedback processes in a large submersed plant bed. Estuaries Coasts 40, 1626–1641 (2017).

    Article  Google Scholar 

  50. 50.

    Orth, R. J. et al. Submersed aquatic vegetation in Chesapeake Bay: sentinel species in a changing world. BioScience 67, 698–712 (2017).

    Article  Google Scholar 

  51. 51.

    Bockmon, E. E. & Dickson, A. G. A seawater filtration method suitable for total dissolved inorganic carbon and pH analyses. Limnol. Oceanogr. Methods 12, 191–195 (2014).

    Article  Google Scholar 

  52. 52.

    Huang, W. J., Wang, Y. & Cai, W. J. Assessment of sample storage techniques for total alkalinity and dissolved inorganic carbon in seawater. Limnol. Oceanogr. Methods 10, 711–717 (2012).

    Article  Google Scholar 

  53. 53.

    Goyet, C., Bradshaw, A. L. & Brewer, P. G. The carbonate system in the Black Sea. Deep Sea Res. A 38, S1049–S1068 (1991).

    Article  Google Scholar 

  54. 54.

    Hiscock, W. T. & Millero, F. J. Alkalinity of the anoxic waters in the Western Black Sea. Deep Sea Res. II 53, 1787–1801 (2006).

    Article  Google Scholar 

  55. 55.

    Verdugo, P. et al. The oceanic gel phase: a bridge in the DOM–POM continuum. Mar. Chem. 92, 67–85 (2004).

    Article  Google Scholar 

  56. 56.

    Cai, W.-J., Wang, Y. & Hodson, R. E. Acid–base properties of dissolved organic matter in the estuarine waters of Georgia, USA. Geochim. Cosmochim. Acta 62, 473–483 (1998).

    Article  Google Scholar 

  57. 57.

    Millero, F. J. Carbonate constants for estuarine waters. Mar. Freshwater Res. 61, 139–142 (2010).

    Article  Google Scholar 

  58. 58.

    Hunt, C. W., Salisbury, J. E. & Vandemark, D. Contribution of non-carbonate anions to total alkalinity and overestimation of pCO2 in New England and New Brunswick rivers. Biogeosciences 8, 3069–3076 (2011).

    Article  Google Scholar 

  59. 59.

    Yang, B., Byrne, R. H. & Lindemuth, M. Contributions of organic alkalinity to total alkalinity in coastal waters: a spectrophotometric approach. Mar. Chem. 176, 199–207 (2015).

    Article  Google Scholar 

  60. 60.

    Cai, W.-J. et al. Alkalinity distribution in the western North Atlantic Ocean margins. J. Geophys. Res. Oceans 115, C08014 (2010).

    Google Scholar 

  61. 61.

    Xu, Y.-Y., Pierrot, D. & Cai, W.-J. Ocean carbonate system computation for anoxic waters using an updated CO2SYS program. Mar. Chem. 195, 90–93 (2017).

    Article  Google Scholar 

  62. 62.

    Pai, S. C., Gong, G. C. & Liu, K. K. Determination of dissolved oxygen in seawater by direct spectrophotometry of total iodine. Mar. Chem. 41, 343–351 (1993).

    Article  Google Scholar 

  63. 63.

    Fonselius, S., Dyrssen, D. & Yhlen, B. in Methods of Seawater Analysis (eds Grasshoff, K. et al.) 91–100 (Wiley, 2007).

  64. 64.

    Kanamori, S. & Ikegami, H. Computer-processed potentiometric titration for the determination of calcium and magnesium in sea water. J. Oceanogr. Soc. Japan 36, 177–184 (1980).

    Article  Google Scholar 

  65. 65.

    Mucci, A. The solubility of calcite and aragonite in seawater at various salinities, temperatures, and one atmosphere total pressure. Am. J. Sci. 283, 780–799 (1983).

    Article  Google Scholar 

  66. 66.

    Stainton, M. P. A syringe gas-stripping procedure for gas-chromatographic determination of dissolved inorganic and organic carbon in fresh water and carbonates in sediments. J. Fish. Res. Board Can. 30, 1441–1445 (1973).

    Article  Google Scholar 

  67. 67.

    Joesoef, A., Kirchman, D. L., Sommerfield, C. K. & Cai, W.-J. Seasonal variability of the inorganic carbon system in a large coastal plain estuary. Biogeosciences 14, 4949–4963 (2017).

    Article  Google Scholar 

  68. 68.

    Taylor, J. R. An Introduction to Error Analysis Ch. 3 (University Science Books, 1997).

  69. 69.

    Hong, Q., Cai, P., Shi, X., Li, Q. & Wang, G. Solute transport into the Jiulong River estuary via pore water exchange and submarine groundwater discharge: new insights from 224Ra/228Th disequilibrium. Geochim. Cosmochim. Acta 198, 338–359 (2017).

    Article  Google Scholar 

  70. 70.

    Hussain, N., Church, T. M. & Kim, G. Use of 222Rn and 226Ra to trace groundwater discharge into the Chesapeake Bay. Mar. Chem. 65, 127–134 (1999).

    Article  Google Scholar 

  71. 71.

    Luek, J. L. & Beck, A. J. Radium budget of the York River estuary (VA, USA) dominated by submarine groundwater discharge with a seasonally variable groundwater end-member. Mar. Chem. 165, 55–65 (2014).

    Article  Google Scholar 

  72. 72.

    Brewer, P. G. & Goldman, J. C. Alkalinity changes generated by phytoplankton growth. Limnol. Oceanogr. 21, 108–117 (1976).

    Article  Google Scholar 

  73. 73.

    Wolf-Gladrow, D. A., Zeebe, R. E., Klaas, C., Körtzinger, A. & Dickson, A. G. Total alkalinity: the explicit conservative expression and its application to biogeochemical processes. Mar. Chem. 106, 287–300 (2007).

    Article  Google Scholar 

  74. 74.

    Fonseca, M. S. in Estuarine Shores: Evolution, Environments and Human Alterations (eds Nordstrom, K. & Roman, C. T.) 261–286 (Wiley, 1996).

  75. 75.

    Ward, L. G., Michael Kemp, W. & Boynton, W. R. The influence of waves and seagrass communities on suspended particulates in an estuarine embayment. Mar. Geol. 59, 85–103 (1984).

    Article  Google Scholar 

  76. 76.

    Russ, E. R. & Palinkas, C. M. Seasonal-scale and decadal-scale sediment-vegetation interactions on the subaqueous Susquehanna River Delta, Upper Chesapeake Bay. Estuaries Coasts 41, 2092–2104 (2018).

    Article  Google Scholar 

  77. 77.

    Gurbisz, C., Kemp, W. M., Sanford, L. P. & Orth, R. J. Mechanisms of storm-related loss and resilience in a large submersed plant bed. Estuaries Coasts 39, 951–966 (2016).

    Article  Google Scholar 

  78. 78.

    Marani, M. et al. On the drainage density of tidal networks. Water Resour. Res. 39, 1040 (2003).

    Google Scholar 

  79. 79.

    Temmerman, S., Bouma, T. J., Govers, G. & Lauwaet, D. Flow paths of water and sediment in a tidal marsh: relations with marsh developmental stage and tidal inundation height. Estuaries 28, 338–352 (2005).

    Article  Google Scholar 

  80. 80.

    D’Alpaos, A., Lanzoni, S., Marani, M. & Rinaldo, A. Landscape evolution in tidal embayments: modeling the interplay of erosion, sedimentation, and vegetation dynamics. J. Geophys. Res. Earth Surf. 112, F01008 (2007).

    Google Scholar 

  81. 81.

    Xie, X., Li, M. & Ni, W. Roles of wind-driven currents and surface waves in sediment resuspension and transport during a tropical storm. J. Geophys. Res. Oceans 123, 8638–8654 (2018).

    Article  Google Scholar 

Download references


This work was supported by grants from the US National Oceanic and Atmospheric Administration (NA15NOS4780184, NA15NOS4780190 and NA18NOS4780179). We acknowledge the USGS, Maryland Department of Natural Resources and Virginia Institute of Marine Science (VIMS) for the monitoring data. We thank C. Hodgkins for assistance with the field work. This is University of Maryland Center for Environmental Science publication number 5821 and reference number UMCES CBL 2020-101.

Author information




W.-J.C. was responsible for the design of the work. J.S. analysed the data. B.C. and J.M.T. co-led the cruises. B.C., J.S., J.B., N.H., K.M.S. and Y.-Y.X. were responsible for sample collection and analysis. Y.Y. and C.N. contributed to the mineralogical analysis. M.L., X.X. and W.N. contributed to physical mixing and particle transport. J.C. and M.S.O. contributed to the weight percentage of CaCO3. J.M.T., C.G. and G.G.W. contributed supplementary materials and data. J.S. and W.-J.C. drafted the manuscript. All authors contributed to discussion and revision of the manuscript.

Corresponding author

Correspondence to Wei-Jun Cai.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Primary Handling Editors: James Super; Xujia Jiang.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data

Extended Data Fig. 1 Sampling sites during August 2016 cruise in the Chesapeake Bay.

Green areas show the coverage of Submersed Aquatic Vegetation (SAV) beds in the Chesapeake Bay in 2016 ( The upper, mid and lower bay (separated by the black lines) accounted for 16.4%, 64.0% and 19.6% of the total SAV coverage in 2016 (39,524 hectares). The arrow shows the outlet of the Susquehanna River. Red circles show the related locations of the four endmembers. Note that stations 82, 83, 85 and 87 are located further offshore in the Mid-Atlantic Bight and were visited during July 2015. Source data

Extended Data Fig. 2 Carbonate system variations and bottom depths in the vicinity of the Susquehanna Flats in 2018.

The dashed line separates the western deep channel and eastern shallow flats, where SAV beds were present. The arrows show the cruise path. Sampling sites are labelled in the inserted maps. The SAV biomass was low in early June (a, c), but was high in early September (b, d) 2018. The Δ values in each station are relative to CB1.1, which was our uppermost station near the Susquehanna River mouth. Source data

Extended Data Fig. 3 SEM images of CaCO3 precipitates on the leaf surface of Vallisneria americana collected from Susquehanna Flats in 2018.

a, semi-spherical crystallites; b, ellipsoidal crystallites; c, polycrystalline maze-like aggregates; d, aggregates with other materials; e, arborisation-like aggregates; f, rice-like aggregates. The atomic composition in Spectrum 32: 41.8% C, 18.4% Ca, 17.2% O, 10.5% K, 6.5% C, 1.9% Na, 1.6% S, 1.3% Mg, 0.8% P; Spectrum 27: 40.8% C, 25.2% O, 14.4% Ca, 9.2% N, 5.3% K, 2.4% Mg, 1.6% P, 1.0% Na; Spectrum 1: 42.9% O, 27.7% Ca, 25.4% C, 1.4% K, 1.2% Si, 0.9% Al, 0.2% Na, 0.2% Mg; sum spectrum in (e): 31.1% C, 29.9% O, 22.3% Ca, 4.6% Fe, 4.4% Si, 3.8% Al, 2.0% K, 1.9% Mg; Spectrum 13: 41.6% O, 38.1% Ca, 12.5% C, 3.7% K, 1.5% Cl, 1.1% Mg, 0.9% Si, 0.5% Na, 0.2% Al. Source data

Extended Data Fig. 4 Effective concentration (C*) and removal (percentage) of TA and Ca2+ in the Chesapeake Bay in August 2016.

The fitting equation for TA (a) at salinity < =22 is C = 0.00002708×S6-0.00336738×S5+0.17376067×S4-4.6574875×S3+64.65219917×S2-344.24526458×S+1342.095396, whereas at salinity >22 the equation is C = 31.791176×S +1172.4787872. The fitting equation for Ca2+ (b) at salinity < =22 is C = -0.00001835×S6+0.00171504×S5-0.05591518×S4+0.67310609×S3-0.73633157×S2+265.9022229×S+368.4115086, while at salinity >22 the equation is C = 270.483366×S +740.833973. C* can be acquired by extending the derivative at any salinity to zero salinity in a concentration-salinity plot. The removal percentage at any salinity relative to freshwater input can be calculated via removal (%) = (C0-C*)/C0×100, where C0 means the concentration at freshwater end. Source data

Extended Data Fig. 5 Numerical model simulation of the transport of fine particles from the Susquehanna Flats in the Chesapeake Bay.

The model simulates suspended sediment concentration (SSC) at surface, mid-depth and bottom water in the bay after the initial release of sediment particles (diameter = 2 μm) from all water depths on the Susquehanna Flats. SSC is shown on a logarithmic scale. The initial concentration is set as 0.5 kg m-3 over the Susquehanna Flats and the release time is on 00:00:00 May 31th, 2016. The output snapshots are the concentrations 1 hour, 1 day, 10 days, 30 days, 60 days and 90 days after the initial release of particles. Source data

Supplementary information

Supplementary Information

Supplementary Figs. 1–4 and Tables 1 and 2.

Source data

Source Data Fig. 1

Water property data for section plot.

Source Data Fig. 2

Cruise data, endmember values and deviation values.

Source Data Fig. 3

Sensor data, SEM images and CaCO3 content data.

Source Data Fig. 4

ΔpH for different biogeochemical processes.

Source Data Extended Data Fig. 1

Latitude and longitude of sampling sites.

Source Data Extended Data Fig. 2

Carbonate chemistry on the Susquehanna Flats.

Source Data Extended Data Fig. 3

SEM images and atomic composition of CaCO3 precipitates on the leaf surface.

Source Data Extended Data Fig. 4

TA and Ca2+ data in August 2016.

Source Data Extended Data Fig. 5

The full path of data repository for model simulation.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Su, J., Cai, W., Brodeur, J. et al. Chesapeake Bay acidification buffered by spatially decoupled carbonate mineral cycling. Nat. Geosci. 13, 441–447 (2020).

Download citation