Integral assessment of heavy metal pollution in Don River estuary soils Dina Nevidomskaya, Tatiana Minkina, Yuri Fedorov, Olga Nazarenko, Natalya Kravtsova and Yuri Litvinov E3S Web Conf., 169 (2020) 01007 Published online: 19 May 2020 DOI: 10.1051/e3sconf/202016901007