Soil cadmium uptake by cocoa in Honduras

Area of Science:

• Environmental Science
• Agronomy
• Toxicology

Background:

• Cadmium (Cd) is a non-essential, toxic trace metal.
• Anthropogenic activities have increased global soil Cd levels.
• EU regulations on Cd in cocoa products necessitate understanding Cd uptake in Theobroma cacao L.

Purpose of the Study:

• To identify factors influencing cadmium uptake in cocoa.
• To analyze relationships between soil/site factors and Cd concentrations in cocoa plant parts.
• To assess Cd levels in cocoa beans against proposed EU limits.

Main Methods:

• Conducted a survey on 55 cocoa farms in Honduras.
• Measured Cd concentrations in cocoa leaves, pod husks, and beans.
• Analyzed relationships between soil properties, site factors, and Cd concentrations.

Main Results:

• Cocoa leaves (2.6±0.4mgkg-1) had higher Cd than beans (1.1±0.2mgkg-1).
• Average bean Cd concentration exceeded the proposed EU limit.
• DGT-available soil Cd was the best predictor (R2=0.5) of bean Cd; geology and soil pH were also significant predictors when DGT was not considered.
• Highest bean Cd concentrations were observed on alluvial substrates.

Conclusions:

• Natural soil variations, particularly geological substrate, significantly impact bean Cd levels.
• Soil Cd concentrations are influenced by factors beyond fertilizers and industrial proximity.
• Understanding soil-Cd dynamics is crucial for managing Cd contamination in cocoa production to meet regulatory standards.