Experimental observations concerning the chlorine inventory in Boom Clay

Experimental data collected so far indicate that the chlorine concentration in Boom Clay pore water depends on experimental procedure. Chlorine concentration is higher in a batch experiment and in a flow-through experiment with NaNO3 (0.1 and 0.5 N) as inlet water than in a pore water sample collected in situ through piezometers. This is explained as being due to the fact that only a part of chlorine inventory in Boom Clay is extractable under the conditions of in situ water sampling. Chlorine inventory is 100 to 400 mg/l determined by batch experiments compared to 27 mg/l typical in a pore water collected in situ.