Demands for more accurate pesticide exposure assessments has driven research into a focus on improving environmental pesticide fate predictions and their transformation products of toxicological significance. This study describes the role of the underlying soil heterogeneity in sorption and degradation of the MCPA pesticide and how heterogeneity affects the sampling/monitoring procedure in environmental pollutant studies. Soil samples were collected from the topsoil (A-horizon: 0-25 cm). A 100 m long profile was sampled parallel with the plough lines. A total of 73 samples were collected, with an equidistance of 1 meter. Each sample is comprised of 20-30 g of moist soil. At the profile center, nine samples make up a local short range variability test. A comprehensive laboratory data set could thus be set up (73 samples) which was used for 14C-labeled, MCPA sorption and mineralisation. Sorption and degradation profiles were assessed for outliers/trends and a variogram was calculated based on all data (with no model fitting) to provide more realistic result according to the objectives of the study. The variographic analysis explains that to include autocorrelation between the samples it is essential to sample locations with less than 15 m distance in between. This project focuses on development of a heterogeneity characterisation for 'next generation' sampling/monitoring and multivariate experimental and modelling practices, allowing implementation of realistic pesticide variability in environmental contaminant assessment studies. The study also has a noteworthy carrying-over potential for related research areas, e.g., soil science in general, contamination studies, and environmental monitoring.

Developing fit-for-purpose decision making tool for large scale representative pesticide fate studies in heterogeneous media: A variographic approach

248th National Meeting (2014)

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