Figure 6From: Humic acids: Their detergent qualities and potential uses in pollution remediationChange in pyrene fluorescence intensity in a 10 ppm HA solution containing 1.0 Ă— 10-7 M pyrene, after MgCl2 addition to a Mg2+ concentration of 3.33 Ă— 10-5 M (adapted from ref. 38, with permission).Back to article page