大型水系的稳定Sr-B-Mo同位素组成对了解这些同位素体系在化学风化过程中的分馏机制和向海洋输出通量有重要意义。本申请项目拟对我国流域化学风化程度较高的大型水系珠江和长江开展研究，分别选定珠江水系的桂平、博罗和长江水系的巴东、大通站，开展持续的观测和采样，了解河水及其携带的悬浮物的稳定Sr-B-Mo同位素组成和相关化学组成的季节、年际变化和对气候环境因素变化的响应，以及水体和悬浮物之间的稳定Sr-B-Mo同位素交换。此项研究可以更深入认识不同气候环境条件下和不同流域地质条件下化学风化过程对这些同位素体系的影响，有助于更准确把握化学风化过程中这些同位素体系分馏的特征和控制机制，同时能更准确地估算出这两个大型水系向海洋输出的稳定Sr-B-Mo同位素通量，为更好限定海水中这些同位素组成的演变提供重要证据。

The stable Sr, B and Mo isptopes in the large rivers are the key for the understanding of the mechanism for the fractionation of these isotopic systematics during chemical weathering, and to constrain their budgets to ocean.The Pearl River and the Changjiang River, in which chemical weathering intensity is fairy intensive, are selected for study. We will carry on time-series observations with time interval of about one month in Guiping and Boluo Stations of the Pearl River and Badong and Datong Stations of the Changjiang River. The stable Sr, B and Mo isotopes, as well as some related elemental and isotopic compositions of both the river water and the suspended materials will be measured.The seasonal and interannual variations of these isotopic compositions and their response to climatic and environmental changes, and the interaction of these isotopic systematics between the river water and the suspended materials will be discussed. The results will be helpful for a better understanding for the influence of chemical weathering on the fractionation of these isotopic systematics under different climatic and environmental conditions and different geological backgrounds.This will benefit the studies on the mechenism for the fractionation of stable Sr, B and Mo isotopes during chemical weathering, and help to constrain the stable Sr,B and Mo isotopic budgets of the Pearl River and the Changjiang River to oceans, which are the important evidences for constraining the evolution of stable Sr, B and Mo isotopes in the ocean.