Ultrafine magnetic particles characterization as a proxy of biogeochemical processes at a brownfield

In this work we present preliminary results of the magnetic properties characterization of sediment samples from a brownfield site in São Paulo – Brazil. We applied interpretation procedures appropriate to study the ultrafine magnetic fraction response of the samples. The distribution of ultrafine particles concentration correlates well with the detected methanogens, suggesting that the microbial activity producing methane may be generating these ultrafine particles, different from naturally occurring magnetic particles at other depths. The results presented here support the use of environmental magnetism techniques to investigate biogeochemical processes of anaerobic microbial activity.