Predicting As, Cd and Pb uptake by rice and vegetables using field data from China

Area of Science:

• Environmental Science
• Agronomy
• Soil Science

Background:

• Heavy metal contamination in croplands poses risks to food safety and human health.
• Accurate assessment of plant uptake is crucial for managing soil contamination.
• Existing models for plant uptake factor (PUF) require validation and refinement.

Purpose of the Study:

• To derive, validate, and compare plant uptake factor (PUF) models for As, Cd, and Pb in rice and vegetables.
• To assess the influence of soil properties, such as pH, on heavy metal uptake.
• To establish a reliable method for calculating soil screening values based on crop concentration limits.

Main Methods:

• Paired crop and soil data from As, Cd, and Pb contaminated croplands in China were collected.
• Single-variable regression of log-transformed plant and soil concentrations was performed.
• Multiple-variable regression incorporating soil concentrations and pH was utilized.
• Model performance was evaluated, and prediction limits were analyzed.

Main Results:

• The median PUF values were not deterministic predictors.
• Natural logarithm transformation of PUF resulted in a Gaussian distribution, suitable for risk assessment.
• Single-variable regression models for As, Cd, and Pb uptake were significant but had large standard errors.
• Soil pH positively influenced Cd uptake by rice and vegetables.
• The upper 95% prediction limits of the multiple regression model for Cd uptake by rice were recommended for soil screening value calculation.

Conclusions:

• Log-transformed PUF provides a robust basis for risk assessment of heavy metal contamination.
• Multiple regression models, considering soil properties, offer improved prediction accuracy for heavy metal uptake.
• The developed model for Cd uptake in rice can inform soil screening value determination for paddy soils.
• This research contributes to better management strategies for heavy metal contaminated agricultural lands.