Table A3.

Model parameters used to simulate Ca ions and proton adsorption onto natural organic matter (from Milne et al., 2001, 2003)

	Fulvic acid		Humic acid
	Carboxylic sites	Phenolic sites	Carboxylic sites	Phenolic sites
Qmax (mol.kg−1)	5·88	1·86	3·35	2·55
nH	0·66	0·76	0·81	0·63
nCa	0·85	0·8	0·78	0·75
p	0·59	0·7	0·62	0·41
logKH	2·34	8·6	2·93	8
logKCa	−2·13	−3	−1·37	-0·43