Pollution of soils (Pb, Cd, Cr, Zn, Cu, Ni) along the ring road of Wrocław (Poland) Anna Hołtra and Dorota Zamorska-Wojdyła E3S Web Conf., 22 (2017) 00066 Published online: 07 November 2017 DOI: 10.1051/e3sconf/20172200066