Liming effects on cadmium stabilization in upland soil affected by gold mining activity

Area of Science:

• Environmental Science
• Soil Science
• Agronomy

Background:

• Heavy metal contamination of agricultural soil poses risks to food safety and human health.
• Cadmium (Cd) is a toxic heavy metal commonly found in contaminated soils, readily taken up by plants.
• Reducing plant cadmium uptake is crucial for mitigating risks associated with consuming contaminated crops.

Purpose of the Study:

• To identify the most effective liming material for reducing cadmium uptake in plants.
• To evaluate the field efficacy of the selected liming material on cadmium reduction in soil and plants.
• To assess the impact of liming on radish growth and yield.

Main Methods:

• Incubation tests comparing four liming materials (CaCO(3), Ca(OH)(2), CaSO(4).2H(2)O, oyster shell meal) at various calcium application rates.
• Field experiments applying the most effective liming material, calcium hydroxide (Ca(OH)(2)), at different rates (0, 2, 4, 8 Mg ha(-1)) to radish (Raphanus sativa L.).
• Analysis of soil cadmium concentrations (NH(4)OAc extractable) and plant cadmium concentrations in radish.

Main Results:

• Calcium hydroxide (Ca(OH)(2)) was the most effective liming material in reducing soil cadmium concentration during incubation.
• Field application of Ca(OH)(2) significantly decreased both soil and radish cadmium concentrations with increasing application rates.
• Approximately 5 Mg ha(-1) of Ca(OH)(2) reduced radish cadmium uptake by about 50% without negatively impacting radish yield or growth.

Conclusions:

• Calcium hydroxide is a highly effective liming agent for reducing cadmium bioavailability and uptake in plants on contaminated soils.
• Increased soil pH and net negative charge induced by Ca(OH)(2) application are key mechanisms for cadmium suppression.
• The findings suggest a practical method for remediating cadmium-contaminated soils and ensuring food safety.