The use of small columns to estimate the effect of soil structure on transport

Abstract

The use of small (10 cm × 4 cm ID) columns was tested to determine the effect of micro soil structure on the transport of atrazine triazine. In the case of a sandy soil, there was no evidence that micro structure played a significant role. The breakthrough curves could be well fitted with a convection-dispersion transport model with linear equilibrium adsorption, and the transport rate was also similar to that calculated with static (batch run) partition coefficients (k d). In the case of an agriculturally modified muck soil, very low transport rates were predicted when static k d values were used. Similar results were obtained from columns of homogenized soil. By contrast, when micro structure was present, small but significant amounts of triazine leached through the columns. The transport model could not be fitted. Small columns can be used to check the suitability of decisions based on static k d values and can serve as a link in the scaling of transport models from laboratory to field conditions. Since they are compact and inexpensive, they are also suitable for geovariability studies.