Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 5 3 2005 10.5194/acpd-5-3921-2005 http://www.atmos-chem-phys-discuss.net/5/3921/2005/ http://www.atmos-chem-phys-discuss.net/5/3921/2005/acpd-5-3921-2005.html http://www.atmos-chem-phys-discuss.net/5/3921/2005/acpd-5-3921-2005.pdf 3921 3957 2005-06-13 Morphological, chemical and optical absorbing characterization of aerosols in the urban atmosphere of Valladolid S. Mogo V. E. Cachorro A. M. de Frutos Grupo de Óptica Atmosférica, Universidad de Valladolid, Valladolid, Spain Dep. de Física, Universidade da Beira Interior, Covilhã, Portugal Aerosol samples were collected from the Valladolid (Spain) atmosphere during 2003–2004 winter using a Dekati PM10 cascade impactor which allows to discriminate four level of particle sizes: greater than 10 µm, between 10 and 2.5, from 2.5 to 1 and less than 1 µm. The size and shape of the aerosol deposits were analyzed by means of individual particles through scanning electron microscope (SEM) technique. Additionally an energy dispersive X-ray analysis (EDX) was performed enabling elemental analysis of a large number of individual particles in a relatively short time. We present a classification in size, shape and composition of the major particulate species present in the Valladolid urban atmosphere. The aerosol concentration is very variable during winter, ranging from 39.86&nbspµg·m−3 to 184.88 µg·m−3 with coarse particle as dominant fraction. Emphasize was given to fine particles, behind 1 µm, for which the visible (from 400 nm to 650 nm) light absorption coefficients were measured using the integrating plate technique. We have made some enhancements relative to the illumination system in the well known integrating plate method, for the absorption coefficients determination. The absorption coefficient ranges from 7.33×10−6 m−1 to 1.01×10−4 m−1 for the 550 nm wavelength. Its visible spectrum decreases with wavelength with greater slope for greater σ values.