The study compared how different soils in China absorb copper, lead, and cadmium in single and mixed metal systems. They found that lead was absorbed more than copper in all soils. The order of metal absorption was lead, copper, cadmium for paddy soils at certain pH levels. Red soil absorbed less heavy metals than paddy soils but increased absorption more with pH changes. The type of minerals in the soil and soil composition affected metal absorption. In mixed metal systems, less metal was absorbed compared to single metal systems, with copper and lead absorption decreasing more with equal metal proportions.