New technique for in situ sampling of particulate matter and colloids in soil and atmospheric fallout

This note describes a new technique for in situ sampling of fine particulate matter (PM) including colloids in natural environments. The technique is based on a microlysimeter which is easy to move between field and laboratory and can be routinely used for in situ monitoring. The design of the device aims at limiting bias and artefacts encountered with current sampling methods based on successive field collection of liquid samples, transport, storage and filtration in the laboratory. Samples are directly collected on transmission electron microscopy (TEM) grids, thus totally eliminating the modifications classically due to handling of samples from collection to analysis. Detailed physical and chemical microscopic studies of individual particles can then be performed in order to fully characterize PM in natural media such as soil solutions, atmospheric fallout, rainfall and any aquatic system. This technique can be applied in a number of research fields, such as the characterization and determination of pollution vectors, the tracing of sources of emissions, or investigations on particle interactions.