Submarine groundwater discharge (SGD) is a crucial material transport pathway across the continent–ocean margins. To evaluate the geochemical impacts of SGD on the western shelf of the northern South China Sea (NSCS), salinity, temperature, and radium were investigated in the summer of 2012. With Ra box models, the flux of SGD was estimated to be (1.0 ± 0.44) × 10⁸ m³ day⁻¹ (3.0 ± 1.3 cm day⁻¹) in the upwelling‐influenced area and (5.4 ± 2.3) × 10⁸ m³ day⁻¹ (1.8 ± 0.8 cm day⁻¹) in the no‐upwelling area. The flux of SGD in the no‐upwelling area estimated using a three end‐member mixing model was (2.1 ± 1.7) × 10⁸ m³ day⁻¹ (0.7 ± 0.5 cm day⁻¹), consistent with the flux estimates above. In the upwelling‐influenced area, the average net fluxes of dissolved inorganic nitrogen (DIN), soluble reactive phosphorus (SRP), dissolved silicate (DSi), dissolved carbon (including dissolved inorganic carbon, DIC, and organic carbon), and total alkalinity (TA) via SGD were 1–27 times greater than those from the upwelling. In the no‐upwelling area, the average SGD‐associated DIN, SRP, DSi, TA, and dissolved carbon fluxes were 22%–42% equivalent to the Pearl River estuarine exports. The net SRP flux from SGD could support 11%–13% of the new production on the shelf. The concentration of DIC on the shelf could increase by about 50 μmol L⁻¹ due to the net DIC fluxes via SGD. These results indicate that SGD is a significant nutrient and carbon source more important than the upwelling and second to the Pearl River on the western shelf of the NSCS and needs to be considered in the shelf biogeochemistry.

中文翻译：

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珠江羽流和上升流对南海北部西部陆架海底地下水排放的影响

海底地下水排放（SGD）是跨大陆-海洋边缘的重要物质运输途径。为了评估SGD对南海北部西部陆架（NSCS）的地球化学影响，于2012年夏季调查了盐度，温度和镭。使用Ra盒模型，SGD的通量估计为（1.0上涌影响区为±0.44）×10 ⁸  m ³ 天^-1（3.0±1.3 cm天^-1），而上流影响区为（5.4±2.3）×10 ⁸  m ³ 天^-1（1.8±0.8 cm天^-1）无居住区。使用三端混合模型估算的无上升流区域的SGD通量为（2.1±1.7）×10 ⁸ m ³ 天^-1（0.7±0.5 cm天^-1），与上述通量估算值一致。在上升流影响区，溶解的无机氮（DIN），溶解的活性磷（SRP），溶解的硅酸盐（DSi），溶解的碳（包括溶解的无机碳，DIC和有机碳）的平均净通量和总碱度（SG）通过SGD上升的幅度是上升流的1–27倍。在没有上升流的地区，与SGD相关的DIN，SRP，DSi，TA和溶解碳通量的平均水平相当于珠江口出口的22％–42％。SGD产生的SRP净流量可以支撑架子上新产品的11％–13％。架子上DIC的浓度可以增加约50μmolL ^-1由于通过SGD产生的净DIC通量。这些结果表明，SGD是重要的养分和碳源，比上升流更重要，并且在NSCS西部大陆架次之于珠江，其次要在大陆架生物地球化学中予以考虑。