Large scale submarine groundwater discharge dominates nutrient inputs to China's coast.
Where this comes from
- Record sourced from PubMed, PMID 40133289.
- Also identified by DOI 10.1038/s41467-025-58103-y and PMC identifier 11937440.
- Licence recorded as CC BY-NC-ND.
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Abstract
Submarine groundwater discharge (SGD) is a nutrient source to coastal waters. However, most SGD estimates are restricted to a local scale and hardly distinguish contributions from fresh (FSGD) and recirculated (RSGD) SGD. Here, we compiled data on radium/radon of groundwater (n ~ 2000) and seawater (n ~ 10,000) samples along ~18,000 km of China's coastal seas to resolve large scale FSGD and RSGD and their associated nutrient loads. Nearshore-scale FSGD ( ~ 3.56 × 10<sup>8</sup> m<sup>3</sup> d<sup>-1</sup>) was only 2% of the total SGD but comparable to RSGD in terms of nutrient loads. Despite large uncertainties quantified via Monte Carlo simulations, SGD was a dominant contributor to China's coastal nutrient budgets, with dissolved inorganic nitrogen, phosphorus and silicate fluxes of ~395, 2.9, and 581 Gmol a<sup>-1</sup>, respectively. Total SGD accounted for 19-54% of nutrient inputs, exceeding inputs from atmospheric deposition and rivers. Overall, SGD helps sustaining primary production along one of the most human-impacted marginal seas on Earth.