HESS Hydrology and Earth System Sciences HESS Hydrol. Earth Syst. Sci. 1607-7938 Copernicus Publications Göttingen, Germany 10.5194/hess-11-328-2007 Variability of dissolved CO<sub>2</sub> in the Pang and Lambourn Chalk rivers Griffiths J. Nutter J. Binley A. Crook N. Young A. Pates J. 17 01 2007 11 1 328 339 Copyright: © 2007 J. Griffiths et al. 2007 This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 Generic License. To view a copy of this licence, visit https://creativecommons.org/licenses/by-nc-sa/2.5/ This article is available from https://hess.copernicus.org/articles/11/328/2007/hess-11-328-2007.html The full text article is available as a PDF file from https://hess.copernicus.org/articles/11/328/2007/hess-11-328-2007.pdf

This paper presents the results of a two-year field campaign to determine the spatial and temporal variability of groundwater interaction with surface waters in two Cretaceous Chalk catchments (the Pang and Lambourn) in the Upper Thames in Berkshire, UK, based on measurement of dissolved carbon dioxide (CO<sub>2</sub>). Average stream water concentrations of dissolved CO<sub>2</sub> were up to 35 times the concentration at atmospheric equilibrium. Mean groundwater concentrations of 85 and 70 times the atmospheric equilibrium were determined from borehole water sampled in the Pang and Lambourn respectively. Diurnal and seasonal variation of in-stream concentration of dissolved CO<sub>2</sub> is not significant enough to mask the signal from groundwater inputs.