Laboratory studies of the chemical weathering of rock from the English Lake District

This study examines the weathering of whole, mixed mineral rocks in the laboratory. Dissolution experiments were carried out in batch type reactors at 10 degrees C in the pH range 2.5 to 6.5. The solutions were analysed for pH, silicon, aluminium, sodium, potassium, magnesium and calcium. The behaviour of these rocks is quantitatively similar to results obtained with pure minerals. The dissolution rate decreases in a linear fashion within the pH range studied. There is an initial fast release of base cations, and with time dissolution begins to reach steady state. Dissolution is not stoichiometric. Fulvic acid was found significantly to increase the rate of dissolution of aluminium at pH 5.5 and 6.5.