Hydrochemistry and Ground‐Water Mixing in Part of the Lincolnshire Limestone Aquifer, England

A hydrochemical study is outlined which demonstrates the mixing of two different ground-water types in the Lincolnshire Limestone aquifer. The two water types consist of a modern recharge water and an ancient possibly connate water. The hydrochemistry of the “interface zone” between the two waters is discussed in detail. In the younger water a relationship between sulphate reduction and bicarbonate is illustrated approaching the “interface zone” and is considered to be related indirectly to the mixing. Carbon isotope content is shown to be radically different in the various ground waters and supports the mixing hypothesis.