Journal of Hazardous Materials 148 (2007) 409–418 Toxic elements at a disused mine district: Particle size distribution and total concentration in stream sediments and mine tailings V. Giuliano a , F. Pagnanelli b,∗ , L. Bornoroni b , L. Toro b , C. Abbruzzese a a Institute of Environmental Geology and Geoengineering (CNR), Via Bolognola, 7, 00138 Rome, Italy b Department of Chemistry, University of Rome “La Sapienza”, P.le A. Moro, 5, 00185 Rome, Italy Received 27 April 2006; received in revised form 23 February 2007; accepted 23 February 2007 Available online 3 March 2007 Abstract Heavy metal and metalloid pollution at a disused pyrite mine was investigated. Five solid samples collected in the area (three stream sediments with different soil texture, a background soil sample and a mine tailing) were characterised by mineral and element composition, particle size distribution (by wet and dry sieving and laser diffraction) and total concentration by acid digestion (Mn, Zn, Cu, Pb, Hg, Cd, Sb and As). X- ray and element analyses denoted a common mineralogical and chemical composition of mainly quartz, clinochlore, muscovite, anorthite, and hematite. Particle size distributions of the five samples showed that stream sediments were characterised by larger percentage of sand range classes (2000–60 m) while background sample and tailing are mainly characterised by gravel particles (>2000 m). Wet and dry sieving procedures gave different particle size distributions, which can be interpreted by laser diffraction analysis and represented by Rosin–Rammler model. Concentrations of Zn, Cu and Cd were higher in the stream sediments than the tailing and background soil, while Mn, As, Sb and Hg are mainly concentrated in the tailing sample. Metal concentrations in the three stream sediment samples are correlated with both particle size dimensions (D 63.2 ) and concentration of geochemical normalizers (iron and aluminium). These correlations are observed also for the pollutants that are mainly concentrated in tailing sample (Mn and As), denoting the importance of surface interactions also for the binding of these elements onto stream sediments. © 2007 Elsevier B.V. All rights reserved. Keywords: Soil pollution; Heavy metals; Metalloids; Disused mine; Particle size distribution 1. Introduction Pollution in soil systems is strictly related to human activi- ties such as industry, agriculture, burning of fossil fuels, mining and metallurgical processes and their waste disposal. Toxic ele- ments, such as heavy metals and metalloids, can be retained by soils and/or mobilised to soil solution by biological and chemical mechanisms with a potential impact on human health (contami- nation of drinking water supplies, uptake by vegetation and input into the food chain). Metal mobility in soil systems depends on the chemical form of soil–metal interactions: metals immobilised by adsorption and precipitation, can be released when the metal retention capacity is overloaded or there is a particular change in soil environmental conditions, enhancing metal mobility (degrada- ∗ Corresponding author. Fax: +39 06 490631. E-mail address: francesca.pagnanelli@uniroma1.it (F. Pagnanelli). tion of organic compounds, change of pH, redox potential or soil solution composition) [1]. The evaluation of the total concentration of metals and metal- loids in soils is generally used as the first reference indicator for comparing pollution level with legislative limits. Nevertheless the natural occurrence of toxic elements in soils, especially in disused mining areas, requires further analyses to detect mobil- isation due to erosion and leaching to groundwater. In this contest, several sequential leaching procedures have been developed to selectively remove metals and metalloids present in different geochemical forms [2]. These procedures are all based on the general principle of reacting a soil sample with chemical solutions with progressively increasing strength. In this way it is possible to distinguish pollutant metals from natural and intrinsic ones. However, these procedures are lab expensive, require optimisation for the specific soil case and present several drawbacks, such as low reproducibility with large particles and encapsulated pollutants, error propagations, strong susceptibility to operating conditions, and re-adsorption of met- 0304-3894/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.jhazmat.2007.02.063