RESUMO
Background:The aim of the study was to investigate bacterial and heavy metal pollution in four landfill sites of Ulaanbaatar. Surveyed landfills included closed and currently operating unlined landfills. Methods:In order to sample, we divided each landfill sites into three zones including zone 1: cover soil or in the boundary of the landfill, zone 2: from the boundary of the landfill to hygiene zone (25 м2to 500 м2out of cover soil), zone 3: from hygiene zone to settlement areas and compared the pollution.Results:The titre of Cl.perfringens, presence of Salmonella and total bacteria were not significantly different for landfill sites. The titre of E.coli and the titre of Proteus for industrial landfill sitewere significantly different than other sites.The titre of E.coliand the titre of Proteusfor the zone 1 were significantly different than the zone 3. The presence of Salmonellaand the total bacteria for the zone 1 was significantly different than the zone 2 and zone 3. The titre of Cl.perfringenswas not significantly different for landfill zones. The bacterial indicators were not significantly different for seasons of the year. Content of heavy metals in soil landfills were Pb 0.1-63 mg/kg, Cr 0.4-5124 mg/kg, Ni 3.2-84 mg/kg, Zn 21.7-776 mg/kg, Cd 0.01-2.8 mg/kg.Conclusions:Microbiological contamination and content of heavy metals in closed unlined landfill are not different from currently operating unlined landfills.