Mechanisms controlling the water chemistry of small lakes in Northern Ireland

Gibbsʹ model of world water chemistry has been adopted as a standard. In the present study, we demonstrate that its applicability to upland lakes is limited due to the modification of water chemistry by catchment processes, in particular, the contribution of rock weathering to sodium ion concentration. In Northern Ireland, 615 lakes between 1 and 100 hectares surface area were sampled and analysed in the summers of 1988–1990. Data from these lakes are used to derive a modified version of Gibbsʹ model, which accounts for local rainfall chemistry and the contribution of rock weathering or other sources to sodium ion concentration.