Large scale submarine groundwater discharge dominates nutrient inputs to China’s coast

Le résumé fourni par la source

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 × 108 m3 d−1) 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−1, 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. The authors resolved large scale fresh and recirculated submarine groundwater discharge (SGD) and their associated nutrient fluxes in China’s coastal seas, revealing a dominant role of SGD in nutrient budgets.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.