, clay minerals were dominated by smectite, illite or chlorite, especially in profile 2 [46,50,57,58]. Smectite and illite may intrinsically retain HREE more efficiently than LREE [46,58]. As shown in Figure 7a, LREE/HREE had a remarkable positive relationship with SiO...
same proportions within those fractions. With respect to current speciation, the exchangeable fractions of Pb and Zn were shown to be dominated by metals weakly bound to clay minerals and other soil solids and soluble metal-bearing phases [43]. Clay minerals are effective sinks from metals such ...