Strategies for including vegetation compartments in multimedia models

Area of Science:

• Environmental Chemistry
• Environmental Modeling
• Ecotoxicology

Background:

• Multimedia fugacity models are crucial for assessing environmental chemical fate.
• Incorporating vegetation compartments can refine model accuracy for specific chemical properties.
• Understanding chemical partitioning in ecosystems is vital for risk assessment.

Purpose of the Study:

• To evaluate the necessity and impact of including vegetation compartments in multimedia fugacity models.
• To define chemical property ranges where vegetation significantly influences environmental fate.
• To suggest equations and parameters for vegetation compartment calculations.

Main Methods:

• Comparison of model outputs with and without vegetation compartments for 12 non-ionic organic chemicals.
• Analysis of chemical uptake via atmospheric deposition and plant transpiration.
• Identification of chemical property thresholds (logK(OA), logK(AW), logK(OW)) for significant vegetation partitioning.

Main Results:

• Vegetation compartments significantly affect chemicals with high octanol-air partition coefficients (logK(OA) > 6) and low air-water partition coefficients (logK(AW) > -6) via atmospheric deposition.
• Transpiration uptake is significant for chemicals with low octanol-water partition coefficients (logK(OW) < 2.5) and low air-water partition coefficients (logK(AW) < -1).
• Model predictions are sensitive to assumptions regarding vegetation partitioning and uptake kinetics.

Conclusions:

• Vegetation inclusion is critical for specific chemical classes, guiding model complexity.
• Property-based criteria can determine the necessity of vegetation compartments in fugacity models.
• Further research is recommended for improved equations on equilibrium partitioning and uptake/depuration kinetics in vegetation.