Effects of methane on the microbial populations and oxidation rates in different landfill cover soil columns

Abstract

A considerable fraction of methane produced in landfills is oxidized by landfill cover soils. In this work, microbial populations and oxidation rates developed in response to the presence of methane were studied in three soil columns simulated landfill cover soil environments. The population of aerobic heterotrophic bacteria was highest in the waste soil, middle in the clay soil, and lowest in the red soil. After exposure to methane-rich environments, the populations of methanotrophic bacteria showed increases in the waste and clay soils. The population of methanotrophic bacteria increased from 30.77× 10⁴ to 141.77× 10⁴cfu g d.w.^{− 1} in the middle layer of the waste soil column as a function of exposure to methane for 120 days. The populations of methanotrophic bacteria were correlated with the potential methane oxidation rates in the waste and clay soils, respectively. The topsoil was observed to be dried in the three soil columns. Most of methane oxidation occurred at the depth of between 10 and 20 cm in the waste soil column, while it took place mainly at the depth of between 20 and 30 cm in the clay soil column.

Keywords:

• Methane oxidation
• microbial population
• landfill cover soil.

Acknowledgments

This work was financially supported by National Natural Science Foundation of China with Grant No. 50478083, and Ministry of Education Key Lab of Environment Remediation and Ecological Health with Grant No. 050001.

Notes

*Mean ± standard deviation (S.D.) (n = 3).

*Mean ± S.D. (n = 3).

**Means with the same small letter(s) and capital letter(s) are not significantly different at p < 0.05 or p < 0.01, respectively, based on least significant differences (LSD) comparisons.

*Mean ± S.D. (n = 3).

**Means with the same small letter(s) and capital letter(s) are not significantly different at p < 0.05 or p < 0.01, respectively, based on LSD comparisons.

*Mean ± S.D. (n = 3).

**Means with the same small letter(s) and capital letter(s) are not significantly different at p < 0.05 or p < 0.01, respectively, based on LSD comparisons.

*Mean ± S.D. (n = 3).

**Means with the same small letter(s) and capital letter(s) are not significantly different at p < 0.05 or p < 0.01, respectively, based on LSD comparisons.