High‐resolution stalagmite oxygen isotope (δ¹⁸O) records are widely employed in palaeoclimate studies as indicators of East Asian Monsoon intensity in southern China. A key issue is whether the East Asian Monsoon or other factors control δ¹⁸O in precipitation in southern China, which requires modern observations to confirm. To understand which factors control the dual isotopes (δD and δ¹⁸O) of precipitation in southern China, δD and δ¹⁸O were measured from 412 precipitation events (including 144 rainwater samples from a total of 43 typhoon events) from May 2015 to April 2020 in Zhanjiang, a tropical city frequently affected by typhoon events in southern China. The overall relationship between δD and δ¹⁸O can be expressed as δD = 8.961 δ¹⁸O + 6.235; significantly lower intercept and larger slope of this relationship compared to these of the global meteoric water line (GMWL) and the China meteoric water line (CMWL). Remarkably, significantly low D‐excess and the lowest δD and δ¹⁸O occurred in the typhoon periods, suggesting that typhoon events could bring large amounts of remote moisture to this tropical city from the Western Pacific and South China Sea. The moisture from remote oceans would affect precipitation with the lowest δ¹⁸O and D‐excess, which could be responsible for the deviation of the slope and intercept from those of the CMWL and GMWL. Therefore, variations of the δ¹⁸O in precipitation are intensively influenced by typhoons, not by the East Asian Monsoon, providing new understanding for the interpretation of palaeo‐isotope data in southern China.

Typhoons frequently induce algal blooms in the open ocean based on the satellite remote sensing data. However, the effects of typhoons on nearshore areas are not fully clarified due to the inaccessibility of in situ sampled data and the low accuracy of satellite data in the nearshore areas. To understand the biogeochemical and ecological changes in semi‐enclosed bays under the influence of typhoons, physicochemical parameters and isotopic compositions of surface water were measured in Zhanjiang Bay during the super Typhoon Mujigae and nontyphoon periods. The results show that the chlorophyll a (Chl a) concentrations inside and outside the bay during these two periods were considerably different. During typhoon periods, the positive apparent oxygen utilization and unsaturated dissolved oxygen (DO) values suggested significant biological degradation in Zhanjiang Bay, rather than the algal blooms reported by previous studies. In contrast, during nontyphoon periods, particulate organic matter (POM: POC and PN) was mainly generated by in situ phytoplankton production, as indicated by a low POC/Chl a ratio (<99), low C/N ratio, and positive correlations between PN, POC, and Chl a. Isotopic analysis of the particulate N (PN) and nitrate (NO₃⁻) indicated that the ¹⁵N‐enriched PN in both periods originally came from sewage‐dissolved inorganic N. These results suggest that the typhoon‐induced decomposition processes, rather than algal blooms, in this semi‐enclosed bay in the northern South China Sea, providing new understanding of the impact of the typhoons on marine biogeochemistry and ecology.

Independent inference of the Asian winter monsoon (AWM), albeit achieved at several sparse sites, has reached no consensus for its variability through the Holocene. A sediment core from the northern coast of the South China Sea (SCS) was utilized to analyze organic biomarkers at (bi‐)decadal resolution, unveiling how SCS oceanic conditions fingerprint the AWM signal. Generally, alkenone sea surface temperature (SST) record, resembling the temporal structures of integrated tropical SST over the past 7,500 years, shows abnormal cool temperatures (up to ~4 °C) during the Little Ice Age and between ~1,200 and 2,500 years BP, when windborne terrigenous hopane compounds experienced considerable increases superimposed on a general increasing trend. Our results, together with augmented SST gradient between the SCS coast and open ocean, consistently suggest AWM strengthening toward the late Holocene. An intensified AWM during cold intervals like the Little Ice Age would have provided strong positive feedback to enhance coastal cooling.

A comprehensive, depth specific (near‐surface to 3,700 m) water isotope (δD and δ¹⁸O) data set of 237 water samples collected from 20 different locations from the Northwest Pacific through the Luzon Strait to the Northern South China Sea (NSCS) are used to clarify the deeper understanding of water mass processes using δ¹⁸O‐salinity (S) and δD‐δ¹⁸O relations. Our study reveals that the δD‐δ¹⁸O correlation has a low slope and the δ¹⁸O‐S correlation has a high slope, which are related to the intrusion of the Kuroshio water and the influence of the coastal current above 200 m on the NSCS, respectively. The isotope mixing model showed that 15% is from the Kuroshio water, 40% from the South China Sea (SCS) Tropical Water, and 45% from the coastal current for water above 200 m in the NSCS. In the intermediate layer (300–1,200 m), a significant δ¹⁸O‐S correlation was found at depths of 300–700 m on the NSCS side, but no correlation was found on the western Pacific side, suggesting that the mixing of the water masses of the South China Sea Intermediate Water and the North Pacific Intermediate Water mainly occurs at depth in the NSCS. In the deeper water (below 1,200 m), positive isotopic values were found at depths below 1,500 m, which refuted the previous knowledge that positive isotopic values only exist in the Luzon Strait at depths above 1,000 m, and the positive isotope water mass would flow with the Deep Pacific Water into the deeper water of the SCS.