The great number of industrial and human activities which originate polluting waste containing heavy metals makes necessary to develop an alternative methodology that allows us to monitoring the pollution and identify the sources and extent of contaminants, in a simple and economical way. Due to the presence of magnetic particles in pollutants, during last decade, the magnetic method has been proposed as an alternative method for monitoring of anthropogenic pollution.
This paper focuses on the study of the correlation between magnetic parameters with the level of contamination by heavy metals in urban soils. We report a magnetic investigation of urban soil samples from Merida, state of Yucatan, Southern Mexico. It appears that most of our samples contain ferrimagnetic minerals as the magnetic carriers, probably coming from the titanomagnetites/titanomaghemites series. This is inferred by the acquisition of isothermal remanent magnetization, which shows that most of samples are almost completely saturated at about 200 mT. The S-200 value is between 0.8 and 1.0, characteristic of ferrimagnetic minerals. The susceptibility vs. temperature measurements also point to some titanomaghemites and titanomagnetites as probable responsible for magnetization.
On the other hand, measurements of magnetic susceptibility (X) at high and low frequencies helped us to determine the high content of superparamagnetic grains in the majority of the samples, although not all of these showed high values of magnetic susceptibility.
We found that the most contaminated samples by Pb and Zn showed the higher SIRM values. We found that magnetic susceptibility increases with Cr content, whereas this parameter decreases with the Sr content.
The SIRM Vs. Xlf graphs help us to identify the anomalous or most polluted samples. We can see how the magnetic monitoring helps us to identify the abnormal samples (soils or urban dusts) in a first probing, which will lead us to choose the samples that require further analysis.
Aguilar B., Bautista F., A. Gogichaishvili and O. Morton. 2011. Magnetic monitoring of top soils of Mérida (southern Mexico). Studia Geophysica et Geodaetica. 55, 377-388. http://www.springerlink.com/content/k02152u472808577/