TY - JOUR

T1 - Mitigation of methane emissions from constructed farm wetlands

AU - Pangala, Sunitha Rao

AU - Reay, David S.

AU - Heal, Kate V.

PY - 2010/1/5

Y1 - 2010/1/5

N2 - Constructed wetlands are increasingly used for water pollution treatment but may also be sources of the greenhouse gas CH4. The effect of addition of two potential inhibitors of methanogenesis – iron ochre and gypsum – on net CH4 emissions was investigated in a constructed wetland treating farm runoff in Scotland, UK. CH4 fluxes from three 15-m2 wetland plots were measured between January and July 2008 in large static chambers incorporating a tunable diode laser, with application of 5 ton ha1 ochre and gypsumin May. CH4 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 CH4 emissions by 64 ± 13% in the field plot and >90% in laboratory incubations compared to controls. Gypsum application of 5 ton ha1 in the field and laboratory experiments had no effect on CH4 emissions, but application of 10 ton ha1 to a sediment core reduced CH4 emissions by 28%. Suppression of CH4 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.

AB - Constructed wetlands are increasingly used for water pollution treatment but may also be sources of the greenhouse gas CH4. The effect of addition of two potential inhibitors of methanogenesis – iron ochre and gypsum – on net CH4 emissions was investigated in a constructed wetland treating farm runoff in Scotland, UK. CH4 fluxes from three 15-m2 wetland plots were measured between January and July 2008 in large static chambers incorporating a tunable diode laser, with application of 5 ton ha1 ochre and gypsumin May. CH4 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 CH4 emissions by 64 ± 13% in the field plot and >90% in laboratory incubations compared to controls. Gypsum application of 5 ton ha1 in the field and laboratory experiments had no effect on CH4 emissions, but application of 10 ton ha1 to a sediment core reduced CH4 emissions by 28%. Suppression of CH4 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.

KW - Constructed wetland

KW - Farm

KW - Gypsum

KW - Methane

KW - Ochre

KW - Pollution swapping

U2 - 10.1016/j.chemosphere.2009.11.042

DO - 10.1016/j.chemosphere.2009.11.042

M3 - Journal article

VL - 78

SP - 493

EP - 499

JO - Chemosphere

JF - Chemosphere

SN - 0045-6535

IS - 5

ER -