This course presents the use of geochemical tools and approaches to understand and reconstruct the history of the waters in the hydrosphere, including any potential anthropic pollution. The use of geochemical tools such as major dissolved elements, stable isotopes of oxygen and hydrogen, and radiogenic isotopes ratios (87Sr/86Sr, 143Nd/144Nd) to identify the origin of waters, the present-day and past circulation paths and mixing processes will be described. Temporal issue will be addressed with cosmogenic isotopes (3H, 14C, 36Cl) to determine the underground water residence time. All these geochemical tools will be applied to study the widespread contamination of the groundwaters by As in the Bengal gulf that represents the largest public health concern in the human history.

By the end of the course you should be able to:

• Identify the appropriate geochemical tools to reconstruct he history of hydrological systems the through time
• Understand the dynamic of the transfers that affect the Hydrosphere