A theory of solute movement is presented for those soils where the liquid‐filled pores can be partitioned into two distinct pore size classes. One region represents macro‐ or interaggregate porosity, and the other represents matrix or intraaggregate porosity. The regions may differ in dispersion coefficient, porosity, and flow velocity. In addition, an interaction coefficient characterizes the linear transfer between regions. A regular perturbation method is used to solve the model equations for small interaction coefficients. It is shown that if the interaction coefficient is large, the model approaches the classical dispersion equation. Esitmates of the interaction and its dependence on flow rate are presented along with the influence of interaction on the shape of the breakthrough curves.

The MAPS programme, which seeks to deepen mitigation ambition in developing countries, is engaged in exploring the concepts of Nationally Appropriate Mitigation Actions (NAMAs) and Low Carbon Development Strategies (LCDS) from a developing country perspective. Here, climate mitigation practitioners in six developing countries were surveyed for their understanding of these concepts (anonymous, personal communications with climate mitigation practitioners in Argentina, Brazil, Chile, Colombia, India, and South Africa). It is found that there is much scope for clarity and conceptual elaboration in this policy space. NAMAs are largely interpreted as mitigation activities packaged for submission to the United Nations Framework Convention on Climate Change (UNFCCC) registry, but are not held to constitute the full set of mitigation activity in a developing country. New terminology may be needed to describe this broader set. A tighter interpretation of LCDS to distinguish between a strategic or coordinating policy action may be useful. Other themes arising include the way 'national appropriateness' is reflected in the concepts, and the role of international policy in deepening mitigation action in developing countries.