文献类型：期刊文献

英文题名：Subsurface Frontal Dynamics Induce Nitrate Regeneration and Phytoplankton Accumulation

作者：Zhou X.; Chen C.; Rao J.; Liu S.; Chen F.; Zhang S.

机构：[1]Guangdong Provincial Key Laboratory of Marine Disaster Prediction and Prevention, Institute of Marine Science, Shantou University, Shantou, China;[2]College of Chemistry and Environmental Science, Guangdong Ocean University, Zhanjiang, China;[3]Institute of Marine Science, Shantou University, Shantou, China;[4]College of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang, China

年份：2026

卷号：131

期号：1.0

外文期刊名：Journal of Geophysical Research: Oceans

收录：Scopus(收录号：2-s2.0-105026072239)

语种：英文

外文关键词：chlorophyll a accumulation; nitrgen cycle; northern South China Sea; oceanic front; stable isotopes

外文摘要：Oceanic fronts significantly affect primary production. While surface fronts are well-studied, subsurface fronts have received relatively little attention. The impacts and underlying mechanisms of subsurface fronts on phytoplankton distribution and nitrogen cycle remain unclear, limiting our understanding of primary production. Based on data from in situ sampling, satellite, and reanalysis, pronounced thermal fronts occurred in the subsurface layers but weakened and disappeared toward the surface and deeper layers of the northern South China Sea. Despite differing formation mechanisms (i.e., dipole eddies and warm offshore water intrusion), both frontal zones exhibited substantially higher chlorophyll a (Chl a) levels than non-frontal zones (on average, Chl a concentrations increased by 77.78% and inventories rose by 88.56%). Positive correlations between frontal intensities and Chl a concentrations, along with enhanced convergence-divergence and vertical processes, suggested that Chl a aggregate relates to physical accumulation. Additionally, evident nitrate (NO3?) loss and isotope enrichment factors (15 (Formula presented.) =?3.4‰ and 18 (Formula presented.) =?4.5‰) supported that Chl a increase were also associated with NO3? assimilation. However, 22.7% of the total NO3? pool in frontal zones was from nitrification, representing an increase of 15.2% compared to non-frontal zones. Elevated regeneration was attributed to enhanced oxygen exchange related to frontal dynamics, as suggested by comparable dissolved oxygen and ammonium levels in both zones, yet with elevated apparent oxygen utilization and NO3? in frontal zones. This study highlights that subsurface fronts not only facilitate phytoplankton aggregation but also drive active NO3? regeneration, thereby leading to an overestimation of new production in oligotrophic oceans. ? 2025. American Geophysical Union. All Rights Reserved.