Articles | Volume 22, issue 20
https://doi.org/10.5194/bg-22-5573-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-22-5573-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Human activities caused hypoxia expansion in a large eutrophic estuary: non-negligible role of riverine suspended sediments
Yue Nan
School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, China
Zheng Chen
Earth, Ocean and Atmospheric Sciences Thrust, The Hong Kong University of Science and Technology (Guangzhou), Guangzhou, 511455, China
Department of Oceanography, Dalhousie University, Halifax, Nova Scotia, Canada
Bo Liang
Eco-Environmental Monitoring and Research Center, Pearl River Valley and South China Sea Ecology and Environment Administration, Ministry of Ecology and Environment of the People's Republic of China, Guangzhou, 510611, China
Jiatang Hu
CORRESPONDING AUTHOR
School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, China
Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou, 510275, China
Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, 519000, China
Related authors
No articles found.
Arnaud Laurent, Bin Wang, Dariia Atamanchuk, Subhadeep Rakshit, Kumiko Azetsu-Scott, Chris Algar, and Katja Fennel
EGUsphere, https://doi.org/10.5194/egusphere-2025-3361, https://doi.org/10.5194/egusphere-2025-3361, 2025
Short summary
Short summary
Surface ocean alkalinity enhancement, through the release of alkaline materials, is a technology that could increase the storage of anthropogenic carbon in the ocean. Halifax Harbour (Canada) is a current test site for operational alkalinity addition. Here, we present a model of Halifax Harbour that simulates alkalinity addition at various locations of the harbour and quantifies the resulting net CO2 uptake. The model can be relocated to study alkalinity addition in other coastal systems.
Zheng Chen, Bin Wang, Chuang Xu, Zhongren Zhang, Shiyu Li, and Jiatang Hu
Biogeosciences, 19, 3469–3490, https://doi.org/10.5194/bg-19-3469-2022, https://doi.org/10.5194/bg-19-3469-2022, 2022
Short summary
Short summary
Deterioration of low-oxygen conditions in the coastal waters off Hong Kong was revealed by monitoring data over two decades. The declining wind forcing and the increasing nutrient input contributed significantly to the areal expansion and intense deterioration of low-oxygen conditions. Also, the exacerbated eutrophication drove a shift in the dominant source of organic matter from terrestrial inputs to in situ primary production, which has probably led to an earlier onset of hypoxia in summer.
Jiatang Hu, Zhongren Zhang, Bin Wang, and Jia Huang
Biogeosciences, 18, 5247–5264, https://doi.org/10.5194/bg-18-5247-2021, https://doi.org/10.5194/bg-18-5247-2021, 2021
Short summary
Short summary
In situ observations over 42 years were used to explore the long-term changes to low-oxygen conditions in the Pearl River estuary. Apparent expansion of the low-oxygen conditions in summer was identified, primarily due to the combined effects of increased anthropogenic inputs and decreased sediment load. Large areas of severe low-oxygen events were also observed in early autumn and were formed by distinct mechanisms. The estuary seems to be growing into a seasonal, estuary-wide hypoxic zone.
Bin Wang, Katja Fennel, and Liuqian Yu
Ocean Sci., 17, 1141–1156, https://doi.org/10.5194/os-17-1141-2021, https://doi.org/10.5194/os-17-1141-2021, 2021
Short summary
Short summary
We demonstrate that even sparse BGC-Argo profiles can substantially improve biogeochemical prediction via a priori model tuning. By assimilating satellite surface chlorophyll and physical observations, subsurface distributions of physical properties and nutrients were improved immediately. The improvement of subsurface chlorophyll was modest initially but was greatly enhanced after adjusting the parameterization for light attenuation through further a priori tuning.
Cited articles
Barbosa, A. B., Domingues, R. B., and Galvão, H. M.: Environmental Forcing of Phytoplankton in a Mediterranean Estuary (Guadiana Estuary, South-western Iberia): A Decadal Study of Anthropogenic and Climatic Influences, Estuar. Coast., 33, 324–341, https://doi.org/10.1007/s12237-009-9200-x, 2010.
Bianchi, T. S., DiMarco, S. F., Cowan, J. H., Hetland, R. D., Chapman, P., Day, J. W., and Allison, M. A.: The science of hypoxia in the Northern Gulf of Mexico: A review, Sci. Total Environ., 408, 1471–1484, https://doi.org/10.1016/j.scitotenv.2009.11.047, 2010.
Breitburg, D., Levin, L. A., Oschlies, A., Grégoire, M., Chavez, F. P., Conley, D. J., Garçon, V., Gilbert, D., Gutiérrez, D., Isensee, K., Jacinto, G. S., Limburg, K. E., Montes, I., Naqvi, S. W. A., Pitcher, G. C., Rabalais, N. N., Roman, M. R., Rose, K. A., Seibel, B. A., Telszewski, M., Yasuhara, M., and Zhang, J.: Declining oxygen in the global ocean and coastal waters, Science, 359, eaam7240, https://doi.org/10.1126/science.aam7240, 2018.
Bussi, G., Darby, S. E., Whitehead, P. G., Jin, L., Dadson, S. J., Voepel, H. E., Vasilopoulos, G., Hackney, C. R., Hutton, C., Berchoux, T., Parsons, D. R., and Nicholas, A.: Impact of dams and climate change on suspended sediment flux to the Mekong delta, Sci. Total Environ., 755, 142468, https://doi.org/10.1016/j.scitotenv.2020.142468, 2021.
Cao, Z., Duan, H., Ma, R., Shen, M., and Yang, H.: Remarkable effects of greening watershed on reducing suspended sediment flux in China's major rivers, Science Bulletin, 68, 2285–2288, https://doi.org/10.1016/j.scib.2023.08.036, 2023.
Carstensen, J., Andersen, J. H., Gustafsson, B. G., and Conley, D. J.: Deoxygenation of the Baltic Sea during the last century, P. Natl. Acad. Sci. USA, 111, 5628–5633, https://doi.org/10.1073/pnas.1323156111, 2014.
Chen, J. Y., Pan, D. L., Liu, M. L., Mao, Z. H., Zhu, Q. K., Chen, N. H., Zhang, X. Y., and Tao, B. Y.: Relationships Between Long-Term Trend of Satellite-Derived Chlorophyll-a and Hypoxia Off the Changjiang Estuary, Estuaries and Coasts, 40, 1055–1065, https://doi.org/10.1007/s12237-016-0203-0, 2017.
Chen, L., Zhang, X., He, B., Liu, J., Lu, Y., Liu, H., Dai, M., Gan, J., and Kao, S.-J.: Dark Ammonium Transformations in the Pearl River Estuary During Summer, J. Geophys. Res.-Biogeo., 125, e2019JG005596, https://doi.org/10.1029/2019JG005596, 2020.
Chen, Z., Yu, L., and Hu, J.: Disentangling the contributions of anthropogenic nutrient input and physical forcing to long-term deoxygenation off the Pearl River Estuary, China, Water Res., 265, 122258, https://doi.org/10.1016/j.watres.2024.122258, 2024.
Cheung, Y. Y., Cheung, S., Mak, J., Liu, K., Xia, X., Zhang, X., Yung, Y., and Liu, H.: Distinct interaction effects of warming and anthropogenic input on diatoms and dinoflagellates in an urbanized estuarine ecosystem, Glob. Change Biol., 27, 3463–3473, https://doi.org/10.1111/gcb.15667, 2021.
Cormier, J. M., Coffin, M. R. S., Pater, C. C., Knysh, K. M., Gilmour, R. F., Guyondet, T., Courtenay, S. C., and van den Heuvel, M. R.: Internal nutrients dominate load and drive hypoxia in a eutrophic estuary, Environ. Monit. Assess., 195, 1211, https://doi.org/10.1007/s10661-023-11621-y, 2023.
Cullen, J. J.: Subsurface Chlorophyll Maximum Layers: Enduring Enigma or Mystery Solved?, in: Annual Review of Marine Science, vol. 7, edited by: Carlson, C. A. and Giovannoni, S. J., 207–239, https://doi.org/10.1146/annurev-marine-010213-135111, 2015.
Dethier, E. N., Renshaw, C. E., and Magilligan, F. J.: Rapid changes to global river suspended sediment flux by humans, Science, 376, 1447–1452, https://doi.org/10.1126/science.abn7980, 2022.
Diaz, R. J. and Rosenberg, R.: Spreading dead zones and consequences for marine ecosystems, Science, 321, 926–929, https://doi.org/10.1126/science.1156401, 2008.
DiToro, D. M.: Sediment flux modeling, John Wiley & Sons, 656 pp., ISBN 9780471135357, 2001.
Domingues, R. B., Barbosa, A. B., Sommer, U., and Galvão, H. M.: Phytoplankton composition, growth and production in the Guadiana estuary (SW Iberia): Unraveling changes induced after dam construction, Sci. Total Environ., 416, 300–313, https://doi.org/10.1016/j.scitotenv.2011.11.043, 2012.
Ge, J., Torres, R., Chen, C., Liu, J., Xu, Y., Bellerby, R., Shen, F., Bruggeman, J., and Ding, P.: Influence of suspended sediment front on nutrients and phytoplankton dynamics off the Changjiang Estuary: A FVCOM-ERSEM coupled model experiment, J. Marine Syst., 204, 103292, https://doi.org/10.1016/j.jmarsys.2019.103292, 2020.
Hagy, J. D., Boynton, W. R., and Jasinski, D. A.: Modelling phytoplankton deposition to Chesapeake Bay sediments during winter-spring: interannual variability in relation to river flow, Estuar. Coast. Shelf S., 62, 25–40, https://doi.org/10.1016/j.ecss.2004.08.004, 2005.
Hong, B., Liu, Z., Shen, J., Wu, H., Gong, W., Xu, H., and Wang, D.: Potential physical impacts of sea-level rise on the Pearl River Estuary, China, J. Marine Syst., 201, 103245, https://doi.org/10.1016/j.jmarsys.2019.103245, 2020.
Howarth, R., Chan, F., Conley, D. J., Garnier, J., Doney, S. C., Marino, R., and Billen, G.: Coupled biogeochemical cycles: eutrophication and hypoxia in temperate estuaries and coastal marine ecosystems, Front. Ecol. Environ., 9, 18–26, https://doi.org/10.1890/100008, 2011.
Hu, J. and Li, S.: Modeling the mass fluxes and transformations of nutrients in the Pearl River Delta, China, J. Marine Syst., 78, 146–167, https://doi.org/10.1016/j.jmarsys.2009.05.001, 2009.
Hu, J., Li, S., and Geng, B.: Modeling the mass flux budgets of water and suspended sediments for the river network and estuary in the Pearl River Delta, China, J. Marine Syst., 88, 252–266, https://doi.org/10.1016/j.jmarsys.2011.05.002, 2011.
Hu, J., Zhang, Z., Wang, B., and Huang, J.: Long-term spatiotemporal variations in and expansion of low-oxygen conditions in the Pearl River estuary: a study synthesizing observations during 1976–2017, Biogeosciences, 18, 5247–5264, https://doi.org/10.5194/bg-18-5247-2021, 2021.
Huang, Y.-G., Yang, H.-F., Jia, J.-J., Li, P., Zhang, W.-X., Wang, Y. P., Ding, Y.-F., Dai, Z.-J., Shi, B.-W., and Yang, S.-L.: Declines in suspended sediment concentration and their geomorphological and biological impacts in the Yangtze River Estuary and adjacent sea, Estuar. Coast. Shelf S., 265, 107708, https://doi.org/10.1016/j.ecss.2021.107708, 2022.
Kasai, M., Brierley, G. J., Page, M. J., Marutani, T., and Trustrum, N. A.: Impacts of land use change on patterns of sediment flux in Weraamaia catchment, New Zealand, Catena, 64, 27–60, https://doi.org/10.1016/j.catena.2005.06.014, 2005.
Lai, Y., Jia, Z., Xie, Z., Li, S., and Hu, J.: Water quality changes and shift in mechanisms controlling hypoxia in response to pollutant load reductions: A case study for Shiziyang Bay, Southern China, Sci. Total Environ., 842, 156774, https://doi.org/10.1016/j.scitotenv.2022.156774, 2022.
Laurent, A., Fennel, K., Ko, D. S., and Lehrter, J.: Climate change projected to exacerbate impacts of coastal eutrophication in the northern Gulf of Mexico, J. Geophys. Res.-Oceans, 123, 3408–3426, https://doi.org/10.1002/2017JC013583, 2018.
Lee, Z.-P., Du, K.-P., and Arnone, R.: A model for the diffuse attenuation coefficient of downwelling irradiance, J. Geophys. Res.-Oceans, 110, https://doi.org/10.1029/2004JC002275, 2005.
Li, D., Gan, J., Hui, C., Yu, L., Liu, Z., Lu, Z., Kao, S.-J., and Dai, M.: Spatiotemporal Development and Dissipation of Hypoxia Induced by Variable Wind-Driven Shelf Circulation off the Pearl River Estuary: Observational and Modeling Studies, J. Geophys. Res.-Oceans, 126, e2020JC016700, https://doi.org/10.1029/2020JC016700, 2021.
Li, G., Liu, J., Diao, Z., Jiang, X., Li, J., Ke, Z., Shen, P., Ren, L., Huang, L., and Tan, Y.: Subsurface low dissolved oxygen occurred at fresh- and saline-water intersection of the Pearl River estuary during the summer period, Mar. Pollut. Bull., 126, 585–591, https://doi.org/10.1016/j.marpolbul.2017.09.061, 2018.
Li, X., Lu, C., Zhang, Y., Zhao, H., Wang, J., Liu, H., and Yin, K.: Low dissolved oxygen in the Pearl River estuary in summer: Long-term spatio-temporal patterns, trends, and regulating factors, Mar. Pollut. Bull., 151, 110814, https://doi.org/10.1016/j.marpolbul.2019.110814, 2020.
Liu, Z., Fagherazzi, S., Liu, X., Shao, D., Miao, C., Cai, Y., Hou, C., Liu, Y., Li, X., and Cui, B.: Long-term variations in water discharge and sediment load of the Pearl River Estuary: Implications for sustainable development of the Greater Bay Area, Front. Mar. Sci., 9, 983517, https://doi.org/10.3389/fmars.2022.983517, 2022.
Lu, Z., Gan, J., Dai, M., Liu, H., and Zhao, X.: Joint Effects of Extrinsic Biophysical Fluxes and Intrinsic Hydrodynamics on the Formation of Hypoxia West off the Pearl River Estuary, J. Geophys. Res.-Oceans, 123, 6241–6259, https://doi.org/10.1029/2018jc014199, 2018.
Ma, C., Zhao, J., Ai, B., Sun, S., and Yang, Z.: Machine Learning Based Long-Term Water Quality in the Turbid Pearl River Estuary, China, J. Geophys. Res.-Oceans, 127, e2021JC018017, https://doi.org/10.1029/2021JC018017, 2022.
Ma, R., Chen, Z., Wang, B., Xu, C., Jia, Z., Li, L., and Hu, J.: Spatiotemporal variations and controlling mechanism of low dissolved oxygen in a highly urbanized complex river system, J. Hydrol.: Reg. Stud., 52, 101691, https://doi.org/10.1016/j.ejrh.2024.101691, 2024.
Murphy, R. R., Kemp, W. M., and Ball, W. P.: Long-Term Trends in Chesapeake Bay Seasonal Hypoxia, Stratification, and Nutrient Loading, Estuaries and Coasts, 34, 1293–1309, https://doi.org/10.1007/s12237-011-9413-7, 2011.
Pitcher, G. C., Aguirre-Velarde, A., Breitburg, D., Cardich, J., Carstensen, J., Conley, D. J., Dewitte, B., Engel, A., Espinoza-Morriberón, D., Flores, G., Garçon, V., Graco, M., Grégoire, M., Gutiérrez, D., Hernandez-Ayon, J. M., Huang, H.-H. M., Isensee, K., Jacinto, M. E., Levin, L., Lorenzo, A., Machu, E., Merma, L., Montes, I., Swa, N., Paulmier, A., Roman, M., Rose, K., Hood, R., Rabalais, N. N., Salvanes, A. G. V., Salvatteci, R., Sánchez, S., Sifeddine, A., Tall, A. W., Plas, A. K. v. d., Yasuhara, M., Zhang, J., and Zhu, Z. Y.: System controls of coastal and open ocean oxygen depletion, Prog. Oceanogr., 197, 102613, https://doi.org/10.1016/j.pocean.2021.102613, 2021.
Roman, M. R., Brandt, S. B., Houde, E. D., and Pierson, J. J.: Interactive effects of Hypoxia and temperature on coastal pelagic zooplankton and fish, Front. Mar. Sci., 6, https://doi.org/10.3389/fmars.2019.00139, 2019.
Su, J., Dai, M., He, B., Wang, L., Gan, J., Guo, X., Zhao, H., and Yu, F.: Tracing the origin of the oxygen-consuming organic matter in the hypoxic zone in a large eutrophic estuary: the lower reach of the Pearl River Estuary, China, Biogeosciences, 14, 4085–4099, https://doi.org/10.5194/bg-14-4085-2017, 2017.
Syvitski, J. P. M. and Kettner, A.: Sediment flux and the Anthropocene, Philos. T. R. Soc. A, 369, 957–975, https://doi.org/10.1098/rsta.2010.0329, 2011.
Wang, B., Hu, J., Li, S., and Liu, D.: A numerical analysis of biogeochemical controls with physical modulation on hypoxia during summer in the Pearl River estuary, Biogeosciences, 14, 2979–2999, https://doi.org/10.5194/bg-14-2979-2017, 2017.
Wang, B., Hu, J., Li, S., Yu, L., and Huang, J.: Impacts of anthropogenic inputs on hypoxia and oxygen dynamics in the Pearl River estuary, Biogeosciences, 15, 6105–6125, https://doi.org/10.5194/bg-15-6105-2018, 2018.
Wang, G., Cao, W., Yang, Y., Zhou, W., Liu, S., and Yang, D.: Variations in light absorption properties during a phytoplankton bloom in the Pearl River estuary, Cont. Shelf. Res., 30, 1085–1094, https://doi.org/10.1016/j.envres.2021.111579, 2010.
Wang, H., Dai, M., Liu, J., Kao, S.-J., Zhang, C., Cai, W.-J., Wang, G., Qian, W., Zhao, M., and Sun, Z.: Eutrophication-Driven Hypoxia in the East China Sea off the Changjiang Estuary, Environ. Sci. Technol., 50, 2255–2263, https://doi.org/10.1021/acs.est.5b06211, 2016.
Wang, J. J., Bouwman, A. F., Liu, X. C., Beusen, A. H. W., Van Dingenen, R., Dentener, F., Yao, Y. L., Glibert, P. M., Ran, X. B., Yao, Q. Z., Xu, B. C., Yu, R. C., Middelburg, J. J., and Yu, Z. G.: Harmful Algal Blooms in Chinese Coastal Waters Will Persist Due to Perturbed Nutrient Ratios, Environ. Sci. Tech. Let., 8, 276–284, https://doi.org/10.1021/acs.estlett.1c00012, 2021.
Wang, K., Chen, J., Jin, H., Li, H., Gao, S., Xu, J., Lu, Y., Huang, D., Hao, Q., and Weng, H.: Summer nutrient dynamics and biological carbon uptake rate in the Changjiang River plume inferred using a three end-member mixing model, Cont. Shelf. Res., 91, 192–200, https://doi.org/10.1016/j.csr.2014.09.013, 2014.
Wang, Y., Wu, H., Lin, J., Zhu, J., Zhang, W., and Li, C.: Phytoplankton Blooms off a High Turbidity Estuary: A Case Study in the Changjiang River Estuary, J. Geophys. Res.-Oceans, 124, 8036–8059, https://doi.org/10.1029/2019jc015343, 2019.
Wei, X., Cai, S., Ni, P.and Zhan, W.: Impacts of climate change and human activities on the water discharge and sediment load of the Pearl River, southern China, 10, https://doi.org/10.1038/s41598-020-73939-8, 2020.
Wen, G., Liang, Z., Xu, X., Cao, R., Wan, Q., Ji, G., Lin, W., Wang, J., Yang, J., and Huang, T.: Inactivation of fungal spores in water using ozone: Kinetics, influencing factors and mechanisms, Water Res., 185, 116218, https://doi.org/10.1016/j.watres.2020.116218, 2020.
Wu, C. S., Yang, S., Huang, S., and Mu, J.: Delta changes in the Pearl River estuary and its response to human activities (1954–2008), Quatern. Int., 392, 147–154, https://doi.org/10.1016/j.quaint.2015.04.009, 2016.
Yang, H., Wang, T., Yang, D., Yan, Z., Wu, J., and Lei, H.: Runoff and sediment effect of the soil-water conservation measures in a typical river basin of the Loess Plateau, Catena, 243, 108218, https://doi.org/10.1016/j.catena.2024.108218, 2024.
Yu, L. and Gan, J.: Reversing impact of phytoplankton phosphorus limitation on coastal hypoxia due to interacting changes in surface production and shoreward bottom oxygen influx, Water Res., 118094 https://doi.org/10.1016/j.watres.2022.118094, 2022.
Yu, L., Fennel, K., and Laurent, A.: A modeling study of physical controls on hypoxia generation in the northern Gulf of Mexico, J. Geophys. Res.-Oceans, 120, 5019–5039, https://doi.org/10.1002/2014JC010634, 2015.
Yu, L., Gan, J., Dai, M., Hui, C., Lu, Z., and Li, D.: Modeling the role of riverine organic matter in hypoxia formation within the coastal transition zone off the Pearl River Estuary, Limnol. Oceanogr., 66, 1–17, https://doi.org/10.1002/lno.11616, 2020.
Zhang, S., Lu, X. X., Higgitt, D. L., Chen, C.-T. A., Han, J., and Sun, H.: Recent changes of water discharge and sediment load in the Zhujiang (Pearl River) Basin, China, Global Planet. Change, 60, 365–380, https://doi.org/10.1016/j.gloplacha.2007.04.003, 2008.
Zhang, Z., Wang, B., Li, S., Huang, J., and Hu, J.: On the Intra-annual Variation of Dissolved Oxygen Dynamics and Hypoxia Development in the Pearl River Estuary, Estuar. Coast., 45, 1305–1323, https://doi.org/10.1007/s12237-021-01022-0, 2022.
Short summary
Human activities are changing the coastal water environment, but the role of suspended sediments in oxygen loss is not well understood. We used a model to compare dissolved oxygen levels and related factors in the 1990s and 2010s in the Pearl River estuary. Reduced suspended sediments and increased pollution have expanded low-oxygen areas by 1.5 times. This highlights the fact that declining suspended sediments increase hypoxia in estuaries, especially with rising nutrients, which needs urgent attention.
Human activities are changing the coastal water environment, but the role of suspended sediments...
Altmetrics
Final-revised paper
Preprint