A novel method for assessing heavy metal distribution in soils coupling laser ablation(LA)-ICP-MS in thin sections with traditional micromorphological and geochemical approaches

In this work we present an application of a new technique to detect and compare microscale distribution of heavy metals and some radionuclides in the main soil features (illuvial pedofeatures, pedogenic matrix and skeletal grains) that were identified in different genetic horizons, i.e. surface and buried mineral horizons (A) and argillic horizons (Bt) from two soil profiles in Sardinia, Italy. This novel method consists in geochemical spot analyses performed with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) on thin sections prepared from undisturbed soil samples, combined with conventional micromorphological observations using both polarizing optical microscopy and scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy microprobe (SEM-EDS).