Artificial colloid tracer tests: development of a compact on-line microsphere counter and application to soil column experiments

摘要

Multi-tracer tests with both solutes and particles allow to parametrise heterogeneous porous media on the basis of the dual porosity model. In soil column experiments both solute and particle tracers were measured on-line at the outflow of the column. For the on-line measurement of particles we developed a flow cytometer with a sensitivity of one single microsphere in 1 ml of water. The microspheres used are latex spheres of 1μm diameter, labeled with a fluorescent dye. The technique is based on the excitation of microspheres with a small diode laser. If a microsphere Passes the laser focus incorporated dye molecules emit fluorescent light.