Introduction Mining and, particularly, the extraction of rock and minerals in open mining have always been considered aggressive activities with a high and negative impact on the environment. Mining operations have, both volun- tarily and under pressure from the legislation, imple- mented an increasing number of measures in order to reduce all the effects and disturbances caused by this activity on the environment. One of the aspects that have been signalled out as important in minimizing these impacts is reducing water pollution. This article presents an in-depth study of the quality of runoff waters from a large granite quarry in Porrin˜o (Galicia), which is located at the northwest corner of Spain. The study area is characterized by a large number of quarries that, due to the continuous operation for decades, have merged in a nearly continuous face with a Enrique Pen˜a Gonza´lez Joaquı´n Sua´rez Lo´pez Jordi Delgado Martı´n Alfredo Ja´come Burgos Jero´nimo Puertas Agudo Analysis of the mobilization of solid loads and heavy metals in runoff waters from granite quarries Received: 22 December 2005 Accepted: 8 March 2006 Published online: 28 March 2006 Ó Springer-Verlag 2006 Abstract The cutting operations of dimension stone at quarries produce a large amount of fines that, in turn, cause a negative environmental im- pact over local surface waters. This article presents a detailed analysis of the mobilized contamination associ- ated with runoff waters in a large granite quarry (200 ha) which is located in Porrin˜o (Galicia, NW Spain), the most important produc- tion centre of dimension stone in Spain. There, an intensive monitor- ing survey was developed in order to characterize the hydrology of the system as well as the release and transport of pollutants. This was accomplished by means of different control sections for the flow and by the collection of 52 random water samples. Automatic samplers were also used to collect 192 water sam- ples associated with runoff generated by significant rain events. For each of the samples collected, a wide battery of analytic determinations was performed, including solid loads, turbidity, organic pollution, nutrient and selected metals. Upon careful examination it has been possible to obtain different parame- ters related to the contamination control, like the ‘‘event mean con- centration’’ (EMC), maximum con- centrations and specific sediment loads. Moreover, a comprehensive statistical study including parameter correlation and cumulative proba- bility analyses helped to understand the pollutant mobilization behaviour within the quarry system. It can be concluded that mobilized contami- nation shows the anomalous pres- ence of some metals, whose concentrations are in excess when compared to the natural rock. This excess metal amount must be attributed to an anthropogenic source associated to mining and cutting operations. Keywords Granite quarries Æ Runoff water pollution Æ Suspended solids Æ Selected metals Æ Statistical analysis Æ Spain Æ Galicia Æ Porrin˜o Environ Geol (2006) 50: 823–834 DOI 10.1007/s00254-006-0254-9 ORIGINAL ARTICLE E. Pen˜a Gonza´lez (&) Æ J. Sua´rez Lo´pez J. Delgado Martı´n Æ A. Ja´come Burgos J. Puertas Agudo Civil Engineering School, University of A Corun˜a, Campus de Elvin˜a s/n, 15071 A Corun˜a, Spain E-mail: epena@udc.es Tel.: +34-9-81167000 Fax: +34-9-81167170 E-mail: jsuarez@udc.es E-mail: jdelgado@udc.es E-mail: ajacome@udc.es