Figure 4. Cd(II) adsorbed in the ternary system Cd-Al20 3-PAA (2 g/L A120 3, [Cd(II)] = IO'5 M, [PAA] = 60 mg C/L, I = 5x1 O'3M NaC104).

T h ro u g h m an y p as t in d u stria l o p e ra tio n s , h igh co n c e n tra tio n s o f heavy m eta ls h av e been d ep o s ited in so il. W aste s co n ta in in g bo th c o m p le x in g ag en ts such as P A A and to x ic m eta ls like C d are d u m p ed in to the g ro u n d w h ere they can p e rs is t y ears later. T h is w ork sh o w s th e im p o rtan ce o f o rg an ic m a tte r on m eta l so rp tio n . O rg an ic m a tte r has la rg e m o lecu le s and th e re fo re is co m p lica te to d e fin e w ell th e ir in te rac tio n s w ith o th e r p a rtic les p resen t in so ils . P A A has m u ch s im p le r m o lecu le s w ith s im ila r c h a rac te ris tic s as o rg an ic m atter. C o n c lu s io n s o b ta in ed on th e ir in te rac tio n s in the en v iro n m en t w ill be used in

d e fin in g th e in f lu en ce o f o rg an ic m a tte r am o n g soil in te rac tio n s . PAA ad so rp tio n o n to АЬОз d em o n s tra te s ch a rac te ris tic s o f a lig an d -ex ch an g e m ech a n ism , ad so rp tio n d ec rea s in g w ith in c reasin g pH . T h e p re sen ce o f PAA in c reases C d (II) u p tak e by A I2O 3. PAA b eco m e s so rb ed o n to th e o x id e su rface , a llo w in g o th e r PAA sites w ith h igh a ffin ity fo r C d (II) to be a v a ilab le fo r the fo rm a tio n o f te rn a ry ad so rp tio n co m p lex es . PAA m ay c o v e r th e su rface and fo rm te rn a ry c o m p lex es w ith som e C d (II), and a lso so m e C d (II) m ay be ad so rb ed d irec tly o n to A I2O 3.