In-Situ Passive Sampling Techniques

In this paper, three in-situ passive sampling techniques and devices, including dialysis peepers, diffusive equilibrium in thin-films (DET) technique and diffusive gradient in thin-films (DGT) technique, are introduced. The principles, devices and advantages of three in-situ passive sampling techniques are summarized. The applications of three in-situ passive sampling techniques, including the in situ sampling of total dissovled concentrations of heavy metals in water and sediment porewaters by dialysis peepers and DET coupled with DGT technique, and the prediction of bioavailability of heavy metals and its speciation measurement with DGT technique, are focused. Comparison with the soil chemical extraction method, DGT can be used as a new method for the measurement of bioavailability of heavy metals. The speciation of heavy metals can be measured by DGT coupled with other techniques (e. g. DET, ion selective electrode, competing ligand exchange and HPLC-ICP-MS methods). The prospects of in-situ passive sampling techniques are also evaluated.