中文摘要：

采用硫酸氢钾（KHSO4）熔融-六氟硅酸（H2SiF6）浸泡的化学方法分离出长江、黄河河口不同粒级沉积物中的石英矿物，使用BrF5为氧化剂提取出石英矿物中的氧，在质谱计上测定石英中氧同位素比值（δ^18O值），结果表明：同一沉积物样品中随粒度由粗变细，石英δ^18O值逐渐增加，长江河口沉积物中石英的δ^18O值比黄河河口沉积物中的稍高，两条河流河口沉积物中相同粒级石英δ^18O值差别主要受流域沉积物物质来源和流域的气候环境差异的影响。

英文摘要：

Quartz in sediments from the Yangtze and Yellow Rivers was separated by potassium hydrogen sulfate （KHSO4） fusing-hydrofluorosilic acid （He2iF6）. Oxygen was extracted from the quartz fraction by BrF5 （used as oxidant）, and then its isotopic composition was analyzed by mass-spectrometer, expressed as 8180 （180/160）values （relative to SMOW）. The results show that 8180 values generally increase with grain size of quartz changing from coarse to fine. The oxygen isotope ratios （δ^18O） of quartz from the Yangtze River are higher than those from the Yellow River. The differences in δ^18O values of the same grain-size quartz between the Yangtze and Yellow Rivers may have resulted from different sediment sources and climate conditions along these two river basins.