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Abstract: The PM10 particulate collected on filters from four air-quality monitoring stations in the city of Torino (Italy) has been investigated by means of detailed magnetic measurements, transmission electron microscopy and energy-dispersive X-ray analysis. The magnetic fraction mainly consists of magnetite-like ferrimagnetic phase and a minor contribution from a high-coercivity phase, which probably results from oxidation of the smallest magnetite grains. The magnetic particles have a grainsize mostly comprised in the single-domain/superparamagnetic range with a large prevalence of the latter. A large fraction of superparamagnetic particles of nanometric dimension were identified in the particulate matter by magnetic techniques and directly observed by electron microscopy. Energy dispersive X-ray elemental analysis showed that ultrafine Fe-rich particles have a spherical shape and are often associated with other metals. The analysis of daily-average variations of magnetic particle concentration found a close correlation of magnetic moment with total nitrogen oxides suggesting that the largest part of magnetic minerals in particulate matter originates from anthropogenic combustion processes. A simple model linking total nitrogen oxides with magnetic particles, for the city of Torino, is proposed. The correlation of magnetic moments and PM10 mass is generally poor because of the different sources of the latter, therefore in the studied contest PM10 is not a good proxy for ultrafine magnetic particles. [ABSTRACT FROM AUTHOR]

The principal aim of a detailed magnetostratigraphic and micropalaeontological investigation of the Jurassic/Cretaceous (J/K) boundary limestones in the basal portion (39m) of the Bosso Valley section in Umbria, central Italy, was to determine precisely the boundaries of magnetozones and narrow reverse subzones, and to find a correlation between magnetostratigraphic data (reflecting global events) and calpionellid zonation. Two reverse subzones were detected in magnetozones M20n and M19n. These are in the same positions relative to the magnetozones above and below as the reverse subzones at the recently studied locality of Brodno, near žilina, West Slovakia. Both the Brodno and Bosso sections so far represent the only magnetostratigraphic profiles across J/K boundary strata in continent-based outcrops in the Tethyan realm displaying both reverse subzones, which correlate well with analogous subzones in the M-sequence of marine magnetic anomalies. The samples of the upper Tithonian and lower Berriasian limestones studied are characterized by a three- or even four-component remanence, with the carrier of palaeomagnetic directions being the C-component, separated by multi-component analysis after progressive thermal demagnetization in the interval of ca. 400°C to the magnetite unblocking temperature (around 550°C). Other aspects of the use of magnetization changes in limestones for possible correlation are also discussed. In addition, the existence of a prominent post-tectonic component of remanent magnetization is indicated. This imprint, recorded in the Bosso Valley and elsewhere in the Tethyan realm, dates most probably to the Neogene and is worthy of further investigation. [Copyright &y& Elsevier]