title: Mitigation of methane emissions from constructed farm wetlands.
abstract: 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 5tonha(-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 5tonha(-1) in the field and laboratory experiments had no effect on CH(4) emissions, but application of 10tonha(-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 degrees C to >90% at 27.5 degrees 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.
authors.affiliation: The University of Edinburgh, UK.
authors.forename: Sunitha R
authors.initials: SR
authors.lastname: Pangala
authors.forename: David S
authors.initials: DS
authors.lastname: Reay
authors.forename: Kate V
authors.initials: KV
authors.lastname: Heal
mesh_terms: D002133:Calcium Sulfate / Q000737:chemistry; D004784:Environmental Monitoring; D005290:Ferric Compounds / Q000737:chemistry; D017752:Greenhouse Effect; D008697:Methane / Q000737:chemistry*; D013696:Temperature; D053833:Wetlands
chemical_list: D005290:Ferric Compounds; C000499:ferric oxide; D008697:Methane; D002133:Calcium Sulfate