The study looked at how to reduce lead, cadmium, and zinc in polluted soil from a mining area. They tested two substances, bentonite and calcium dihydrogen phosphate, to see which one worked better. Both substances helped lower lead and cadmium levels in the soil, but calcium dihydrogen phosphate was more effective at reducing all three metals. Bentonite increased lead and cadmium levels at first before decreasing them, while calcium dihydrogen phosphate consistently lowered them. Overall, calcium dihydrogen phosphate was better at fixing lead, cadmium, and zinc in the polluted soil.