Constructed wetlands are increasingly used for water pollution treatment but may also be sources of the greenhouse gas CH 4 . The effect of addition of two potential inhibitors of methanogenesis - iron ochre and gypsum - on net CH 4 emissions was investigated in a constructed wetland treating farm runoff in Scotland, UK. CH 4 fluxes from three 15-m 2 wetland plots were measured between January and July 2008 in large static chambers incorporating a tunable diode laser, with application of 5 ton ha -1 ochre and gypsum in May. CH 4 fluxes were also measured from control and ochre- and gypsum-treated wetland sediment cores incubated at constant and varying temperature in the laboratory. Ochre addition suppressed CH 4 emissions by 64 ± 13% in the field plot and >90% in laboratory incubations compared to controls. Gypsum application of 5 ton ha -1 in the field and laboratory experiments had no effect on CH 4 emissions, but application of 10 ton ha -1 to a sediment core reduced CH 4 emissions by 28%. Suppression of CH 4 emissions by ochre application to sediment cores also increased with temperature; the reduction relative to the control increased from 50% at 17.5 °C to >90% at 27.5 °C. No significant changes in N removal or pH and potentially-toxic metal content of sediments as the result of inhibitor application were detected in the wetland during the study. Crown Copyright © 2009.
Pangala, S. R., Reay, D. S., & Heal, K. V. (2010). Mitigation of methane emissions from constructed farm wetlands. Chemosphere, 78(5), 493–499. https://doi.org/10.1016/j.chemosphere.2009.11.042