1. The glacial effect: when water vapor with lighter oxygen isotopes enters high latitudes and falls as snow, light water molecules are trapped in the glacier until they melt and return to the ocean. Therefore, during the glacial period with large glacial development, the isotopes of oxygen isotopes in seawater were about 1.0 ~ 1,7‰ heavier than those in the interglacial period. By contrast, if the glaciers were to melt completely today, the isotopes of oxygen in the ocean would change by -1.0‰ globally.

2. Salinity and transpiration effects: when regional seawater is affected by the injection of fresh water from tianshui or rivers, the oxygen isotopes in seawater are relatively light because they are mixed with water bodies of lighter oxygen isotopes, and the salinity effect will be more significant in the higher latitudes because the oxygen isotopes in the source water bodies are lighter. The isotopic values of oxygen isotopes in Antarctic glaciers and Greenland ice cores are about -50 ~ -55‰ and -32 ~ -37‰, both of which are much lower than 0‰ of oxygen isotopes in the global sea water. Transpiration, contrary to precipitation, will also affect the oxygen isotopic value of regional seawater. When vigorous transpiration is carried out, water molecules with relatively light isotopic value will continue to leave the seawater and enter the atmosphere, making the oxygen isotopic value of regional seawater heavier than that of other seawater.

3. Lithospheric and hydrosphere exchange: Due to an exchange process with a time scale of thousands of years, such as hydrothermal action and weathering near the mid-ocean ridge, O released from the lithosphere can change the value of seawater oxygen isotopes in the region.