1 1 Controls on the spatial and temporal variability of 2 222 Rn in riparian groundwater in a lowland Chalk 3 catchment 4 5 N.J. Mullinger, J.M. Pates*, A.M. Binley and N.P. Crook 1 6 Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK 7 8 9 10 11 * Corresponding author. Tel.: +44 1524 593896; fax: +44 1524 593985. 12 E-mail address: J.Pates@lancaster.ac.uk (J.M. Pates). 13 1 Current address: Geophysics Department, Stanford University, Stanford 94305, 14 USA 15