Evaluating the use of Sr, Pb, and U isotopes for fingerprinting surface and groundwaters in southern New Hampshire

Abstract

Increased pressure on fresh water reserves in southern New Hampshire requires new methods for monitoring exploitation. In a pilot study, surface water and groundwater samples from southern New Hampshire were analyzed for Sr, Pb, and U isotopes to test if they could be used to distinguish between different reservoirs (surface waters, bedrock wells, and sand and gravel wells). Detecting and monitoring communication between different aquifers is an essential part of water management, and mixing between the reservoirs due to overproduction of the wells could adversely impact drinking water quality. The results show that a mix of ²³⁴U/²³⁸U, ²⁰⁶Pb/²⁰⁴Pb, and ²⁰⁸Pb/²⁰⁴Pb ratios was the most useful in distinguishing between the reservoirs. This method has great potential for the long-term monitoring of water wells to prevent overproduction.