Optimizing the potential of iron oxide-based tracers

Abstract

So far, it does not exist a set of tracers which fulfill all the characteristics for being an idealsediment tracer such as, environmentally friendly, inexpensive or easily analysed (Zhang et al.,2001). For this reason, and in order to address some of the unsolved issues of water erosionprocesses, more research enquiring into the development of these soil and sediment tracers isneeded.Iron oxide-based tracers has been already tested in several water erosion trials with satisfactoryresults (e.g. Guzmán et al., 2010, 2013, 2015). In 2015, three cascade plots with a different ironoxide (magnetite, hematite and goethite) each were set up in order to evaluate soil redistributionafter the rainy season (Obereder et al., 2016). While these authors presented the total iron contentof sediments after clorhydric acid extraction, the present study will show only the free iron contentof soil and sediments using a different extraction method (CBC, citrate-bicarbonate-ditionite), asthis method is more adequate in high iron content soils, as is our case.The results depict the suitability of the CBD method extracting the three tracers with an averagerecovery rate of 0.7. The analysis of the iron content of soil and sediment samples indicates arelatively low movement of soil although showing significant statistical differences withbackground and mixture values. These results are in line with the ones detected by the magneticsusceptibility measurements. Further textural and visible spectrum analysis of the samples willallow to determine the possible selectivity factor and to discriminate qualitative and quantitativelyhematite and goethite tracers, respectively.