Water studies in Wookey Hole Cave, Somerset, UK

Water samples were collected by members of the Cave Diving Group from the River Axe in Wookey Hole Cave between the Entrance and Wookey 23. The samples were analysed for all major constituents, enabling ion balances to be used to assess analytical reliability. The results showed that water in the Static Sump at the beginning of Wookey 23 had very much less magnesium than water in the Main Stream between the surface and Sump 22. This result was confirmed by the analysis of a second set of samples. The results of the remaining constituents showed that water in the Static Sump had the same origin as that in the River Axe. Only magnesium bicarbonate concentrations were different. A third set of samples included a sample from Sump 25. Results showed that the location of the "Unknown Junction", from where water flows to the Static Sump by a different route from the majority of the River Axe, is upstream of Sump 25. Analytical difficulties were caused by high concentrations of suspended calcium carbonate in the river during high water conditions in the winter of 1996/97, and part of the paper deals with analytical problems caused by such suspensions in the River Axe.