Fate and transport of monoterpenes through soils. Part I. Prediction of temperature dependent soil fate model input-parameters.

Monoterpenes are C10H(n)O(n') compounds of natural origin and are potentially environmentally safe substitutes for traditional pesticides. Still, an assessment of their environmental behaviour is required. As a first step in a theoretical study focussing on monoterpenes applied as pesticides to terrestrial environments, soil fate model input-parameters were determined for 20 monoterpenes with widely different structural characteristics.

Fate and transport of monoterpenes through soils. Part II: calculation of the effect of soil temperature, water saturation and organic carbon content.

This theoretical study was performed to investigate the influence of soil temperature, soil water content and soil organic carbon fraction on the mobility of monoterpenes (C10HnOn') applied as pesticides to a top soil layer. This mobility was expressed as the amount volatilized and leached from the contaminated soil layer after a certain amount of time. For this, (slightly modified) published analytical solutions to a one dimensional, homogeneous medium, diffusion/advection/biodegradation mass balance equation were used.

Calculation of the interaction between dissolved organic carbon and organic micropollutants by three dimensional force field methods.

A 3D optimized potential for liquid simulation (OPLS) force field method with 6-31G* atomic charges and a geometrical optimization approach was studied for the calculation of enthalpies of transfer at 300 K of partitioning processes. A 3D fulvic acid model of dissolved organic carbon was built. Limonene, alpha-pinene, fluoranthene, p,p'-DDT, and 2,4-D were inserted into a general site of preference, and interaction energies were calculated.

Gas chromatographic determination of vapour pressure and related thermodynamic properties of monoterpenes and biogenically related compounds.

The (subcooled) liquid vapour pressure, heat of vapourization and gas-liquid heat capacity difference of monoterpenes and biogenically related compounds were determined by a gas-liquid chromatographic method based on Kovats retention indices. Compared to those used in previous studies using the same method, these compounds are structurally diverse and have relatively low boiling points. Despite of this and even though the difference in activity coefficients in the chromatographic column stationary phase between the test and reference compounds were ignored, results for vapour pressure compare favorably with experimental literature data.