This study aimed to understand the effects of nonlinear internal waves (NLIWs) on nutrient-involved biogeochemical processes and the consequences in the continental margin off Dongsha Atoll (DA) in the northern South China Sea (NSCS). Shipboard and mooring observations were conducted to determine hydrological and biogeochemical conditions mainly from two transects covering the DA-associated upper slope, shelf break, and shelf zones. A dense array of thermistor moorings and a temperature-fluorescence-sediment trap array were deployed on the same transect to determine the short-period variability of transport and shoaling of NLIWs across the shelf and to link physical variability to biogeochemical consequences induced by NLIW events. The shoaling of NLIWs appeared to uplift cooler and nutrient-rich subsurface water into the nutrient-deplete surface in shelf and nearshore environments as well as increase nutrient concentrations and biological production. We observed shoaling events that induced a notable range of upward fluxes in nitrate and nitrite (0.42–2.92 mmol N m⁻² d⁻¹) onto the euphotic zone to enhance and sustain new production, depending on the strength of shoaling activity in various observations. The shoaling-derived new production may fully elucidate the amount of sinking fluxes of particulate organic carbon measured from the shoaling field. According to short-time sequential observations during the passage of a single NLIW, the depressed waves may play a crucial role in enhancing the vertical transfers of surface-replete dissolved gases, carbon, or suspended constituents through the surface layers of stratified waters. This NLIW forcing appears to be effective in supplying cooler and nutrient-rich water to the DA-associated coral community, and this may be vital for improving the future development and conservation of the coral ecosystem.

本研究旨在了解非线性内波 (NLIWs) 对养分涉及的生物地球化学过程的影响以及对南海北部 (NSCS) 东沙环礁 (DA) 外大陆边缘的影响。进行了船上和系泊观测，主要从覆盖与 DA 相关的上坡、陆架断裂和陆架带的两个断面确定水文和生物地球化学条件。密集的热敏电阻系泊阵列和温度-荧光-沉积物捕集器阵列部署在同一横断面上，以确定 NLIW 跨大陆架运输和浅滩的短期变化，并将物理变化与 NLIW 事件引起的生物地球化学后果联系起来。NLIW 的浅滩似乎将较冷且营养丰富的地下水抬升到陆架和近岸环境中营养耗尽的表面，并增加了营养浓度和生物产量。我们观察到浅滩事件导致硝酸盐和亚硝酸盐（0.42–2.92 mmol N m^-2 d ^-1 ) 到透光区以增强和维持新的生产，这取决于各种观察中浅滩活动的强度。浅滩衍生的新产量可以充分阐明浅滩油田测得的颗粒有机碳下沉通量的大小。根据单个 NLIW 通过期间的短时间连续观测，被抑制的波可能在增强地表丰富的溶解气体、碳或悬浮成分通过分层水表层的垂直转移方面发挥关键作用。这种 NLIW 强迫似乎可以有效地为与 DA 相关的珊瑚群落提供更凉爽和营养丰富的水，这对于改善珊瑚生态系统的未来发展和保护可能至关重要。