In the East Asian monsoon area, stalagmites generally record lower and higher oxygen isotope (δ¹⁸O) levels during warm humid interglacial and cold dry glacial periods, respectively. Here, we report unusually low stalagmite δ¹⁸O from the last glacial period (ca. 32.2–22.3 ka) in Fukugaguchi Cave, Niigata Prefecture, Japan, where a major moisture source is the East Asian winter monsoon (EAWM) that carries vapor from the warm surface of the Japan Sea. The δ¹⁸O profile of this stalagmite may imply millennial-scale changes, and high δ¹⁸O intervals that are related to Dansgaard–Oeschger (D–O) interstadials. More importantly, the stalagmite exhibits low overall δ¹⁸O values; the mean δ¹⁸O (− 8.87‰) is distinctly lower than the mid-Holocene mean of another stalagmite from the same cave (4.2–8.2 ka, − 7.64‰). An interpretation assuming a more intense EAWM and greater vapor transportation during the last glacial period, compared with the mid-Holocene, contradicts the limited inflow of the Tsushima Warm Current into the Japan Sea because of lowered sea level. Additionally, our model calculation using δ¹⁸O data from meteoric water indicated that the amount effect of winter meteoric water was insignificant (1.2‰/1000 mm). Low stalagmite δ¹⁸O for the last glacial period in Fukugaguchi Cave most likely resulted from ¹⁸O-depleted surface water, which developed in the isolated Japan Sea. The estimated amplitude of the δ¹⁸O decrease in surface water was ~ 3‰ at most, consistent with the abnormally low values for foraminifera (by ~ 2.5‰) in sediment during the last glacial period, shown by samples collected from the Japan Sea. This is the first terrestrial evidence of ¹⁸O depletion in Japan Sea surface water during the last glacial period.

在东亚季风区，石笋通常（δ记录较低和较高的氧同位素¹⁸ O）温暖期间水平湿润的间和冷干冰周期，分别。在这里，我们报告异常低石笋δ ¹⁸从Fukugaguchi洞，日本新泻县，其中一个主要的水分来源是东亚冬季风（东亚冬季风），从带有蒸汽末次冰期（约32.2-22.3 KA）O日本海的温暖表面。的δ ¹⁸这石笋O配置文件可能意味着千年尺度的变化，和高δ ^18个ö使用有关丹斯加德-Oeschger（d-O）interstadials间隔。更重要的是，石笋表现出低的总δ ^18个O值; 平均δ ¹⁸O（− 8.87‰）明显低于同一洞穴中另一颗石笋的全新世中期平均值（4.2–8.2 ka，− 7.64‰）。与全新世中期相比，一种假设假设在最后一个冰期，EAWM更加强烈，蒸气输送更多，这与对马岛对流由于日本海平面降低而流入日本海的情况有限。此外，我们使用δ模型计算^18个从大气水O数据表明，冬季大气水的量的效果显着（1.2‰/ 1000毫米）。低石笋δ ¹⁸ O代表在Fukugaguchi洞穴末次冰期最有可能是由于¹⁸ O型耗尽地表水，这在隔离日本海发展。的δ的估计的幅度¹⁸从日本海收集的样本显示，地表水的O减少最多约为3‰，与上一个冰川期沉积物中有孔虫的异常低值（约2.5‰）相符。这是最后一个冰期日本海表层水消耗¹⁸ O的第一个地面证据。