Magnetic techniques applied to study the accumulation time period of urban/industrial dust in lichens

SINITO A. M.; MARIE, D.C.; CHAPARRO, MARCOS A.E.

Praga

Congreso; 26th IUGG 2015 General Assembly; 2015

INTERNATIONAL UNION OF GEODESY AND GEOPHYSICS

26th IUGG General AssemblyA06c-A06c A06/A07 Applied Rock Magnetism (Div. I) / Theoretical and Experimental Rock Magnetism (Div. I)Abstract: IUGG-0296Magnetic techniques applied to study the accumulation time period of urban/industrial dust in lichensA.M. Sinito 1, D.C. Marié 1, Chaparro, M. A.E. 11 CIFICEN, CONICET - Universidad Nacional del Centro Exactas, Tandil, Argentina - This study assesses the accumulation time period of urban/industrial dust in the lichen Parmotrema Pillosum, using di in Tandil City (37º19.5?S; 59º08.3?W), Argentina. We selected a control (without or with low pollution load) site for collecting lichens to transplant. Such lichens were prepared and transplanted in va affected by different pollutant emission sources (vehicle traffic and metallurgical factories). Twelve samples for each site were prepared and simultaneously transplanted in order to make monthly collections. Magnetic susceptibility (X), anhysteretic and isothermal magnetizations (ARM, IRM) were measured. Also, associated parameters were used, such as k ratio, SIRM/X and X/X. In addition, deposited particles onto the lichen surf observed by scanning electron microscopy (SEM) and analyzed by x dispersive spectroscopy (EDS). The analysis of the set of parameters indicates the predominance of ferromagnetic minerals, like (titano)magnetite. The King´s plot indicate grains (less than 0.1 mm). There is a general trend of increase for parameters related to magnetic concentration, though a slight decrease is observed after rainy periods, apparently due to a washing effect of surface particles. The magnetic grain size dependent parameters decrease with time while magnetic concentration increases, suggesting that higher magnetic concentrations are associated with the accumulation of coarser magnetic grains. SEM and EDS indicate higher Fe content and the presence of spherules produced by industrial activity near the collection sites.