Effect of lead and chloride ions on methane production in arable soils

Cultivated soils in high water conditions can be a source of methane (CH4). Despite the significant introduction of lead (Pb) into soils with fertilizers or sewage sludge, there are few reports concerning its impact on methane production in arable soils. The main premise of the study was to characterize the response of methanogenesis after soil contamination with Pb. For this reason, the effect of Pb on CH4 production in three different mineral arable soils was investigated. Lead, in the chloride form, was added at two concentrations, which were established based on the Sewage Sludge Directive (300 and 1 500 mg kg–1). Additionally, two types of controls were used – water and CaCl2 with chloride ions. It was observed that the process could be slowed down at the lower dose and that methane production was totally inhibited at the higher dose. Additionally, the inhibitory effect of the chloride ions on the process was also observed in the control samples. Despite the inhibition of methanogenesis in the soil, which has a positive effect on reducing the amount of the gas released, this process cannot be analysed individually. Other reactions in the soil should also be taken into consideration, and these changes which occur under the influence of the various factors should be investigated further.