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WP11 Risk Management
() Modelling the plant uptake of organic chemicals for risk assessment.
Collins, C1, Fryer, M1, Grosso, A2, 1 Imperial College, London, UK2 Environment Agency, Solihull, UK
ABSTRACT- Models for the plant uptake of organic chemicals are an essential component of any exposure model for assessing the risks of contaminated land. A number of plant uptake models have been reported in the literature over the last 15 years, but there has been little analysis of the strengths and weaknesses of these models when compared to independent experimental data sets. Additionally the understanding of plant uptake of organic contaminants has expanded since some of these models were developed. Most notably there has been improvements in our understanding of the aerial deposition pathway. The paper will present our recent model intercomparison and validation exercise using a range of models differing in complexity and approach. These included simple regression, semi-mechanistic models and fugacity based approaches. The model based on the work of Ryan et al. (1988) performed best overall in this exercise. This currently underpins the Contaminated Land Exposure Assessment (CLEA) model developed by the Environment Agency. In general all the plant uptake models over predicted root concentrations, but underpredicted shoot concentrations. The latter finding is proposed to be a result of plant contamination via the soil-air-pathway or the particle deposition pathway which were not accounted for in any of the models used in the study. How models may account for these pathways will be discussed in conjunction with future research needs to improve the modelling of this exposure pathway.
Key words: exposure, risk assessment, plant uptake, modelling
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