Microbiological contamination and content of heavy metals in unlined landfill sites of Ulaanbaatar

Abstract

<p class="abstract"><strong>Background:</strong> 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.</p><p class="abstract"><strong>Methods:</strong> 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 м<sup>2</sup> to 500 м<sup>2</sup> out of cover soil), zone 3: from hygiene zone to settlement areas and compared the pollution. </p><p class="abstract"><strong>Results:</strong> The titre of <em>Cl. perfringens, </em>presence of <em>Salmonella </em>and total bacteria were not significantly different for landfill sites. The titre of <em>E. coli and </em>the titre of <em>Proteus </em>for industrial landfill site<em> </em>were significantly different than other sites. The titre of <em>E. coli</em> and the titre of <em>Proteus</em> for the zone 1 were significantly different than the zone 3. The presence of <em>Salmonella</em> and the total bacteria for the zone 1 was significantly different than the zone 2 and zone 3. The titre of <em>Cl. perfringens</em> was 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.</p><p class="abstract"><strong>Conclusions:</strong> Microbiological contamination and content of heavy metals in closed unlined landfill are not different from currently operating unlined landfills.</p><p class="abstract"> </p>