Effects of nickel and cobalt on methane production and methanogen abundance and diversity in paddy soil.

backgroundPaddies are an important anthropogenic source of methane emissions to the atmosphere, and they are impacted by heavy metal pollution. Nickel (Ni) and cobalt (Co) pollution might either enhance or mitigate CH

methodsAn incubation experiment was conducted, and different Ni and Co concentrations were added to test the effects of trace metals on methane production in paddy soil. The archaea community structure and the abundance of methanogen functional groups in the paddy soil with added Ni and Co were detected using high-throughput sequencing and quantitative PCR based on the 16S rRNA and mcrA (methyl coenzyme M reductase) genes, respectively.

resultsThe highest methane production rate was 561 mg CH DISCUSSION: Our results indicated that the contamination of soil by Ni and Co significantly affected total methanogens abundance and specific methanogen functional groups. Ni and Co additions to paddy soil promoted methanogenic activity at low concentrations, while they had inhibitory effects at high concentrations. Because paddy soils largely contribute to methane emissions and are increasingly exposed to heavy metal pollution, our results show that future assessments of greenhouse gas flux from paddy soils should take into account the effects of pollution by Ni and Co.