Analysis of perfluorooctanoate (PFOA) and other perfluorinated compounds (PFCs) in the River Po watershed in N-Italy

C7-C11 perfluorinated carboxylates (PFACs) and perfluorooctansulfonate (PFOS) were analysed in selected stretches of the River Po and its major tributaries. Analyses were performed by solid-phase extraction (SPE) with Oasis HLB cartridges and methanol elution followed by LC-MS-MS detection using 13C-labelled internal standards. High concentration levels ( approximately 1.3 microg l(-1)) of perfluorooctanoate (PFOA) were detected in the Tánaro River close to the city Alessandria. After this tributary, levels between 60 and 337 ng l(-1) were measured in the Po River on several occasions. The PFOA concentration close to the river mouth in Ferrara was between 60 and 174 ng l(-1). Using the river discharge flow data in m3 s(-1) at this point (average approximately 920 m3 s(-1) for the year 2006), a mass load of approximately 0.3 kg PFOA per hour or approximately 2.6 tons per year discharged in the Adriatic Sea has been calculated. PFOS concentration levels in the Po River at Ferrara were approximately 10 ng l(-1).     

Perceptual deformation induced by visual motion

The perceived position of a moving object can be misleading because the object has advanced while its previous retinal image has been transmitted through the visual stream, leading to a mismatch between actual location and its neural representation. It has been suggested that the human visual system compensates for neural processing delays to retrieve instantaneous position. However, such a mechanism would require a precise measure of the actual delay in order to provide a reliable position estimate. A novel illusory deformation of moving contours demonstrates that humans misjudge the spatial relationship between parts of coherently moving targets, and therefore do not perfectly account for neural delays. The size of this deformation increases with growing speed. In some subjects this illusion can be reversed by varying the luminance of individual dots; a manipulation that affects the neural delays. Our experiments agree with other evidence that the capacity of the visual system to compensate for processing delays is limited.