The impact of sludge amendment on gas dynamics in an upland soil: monitored by membrane inlet mass spectrometry S.K. Sheppard a, * ,N.Gray b , I.M. Head b ,D.Lloyd a a Microbiology Group, Cardiff School of Biosciences, University of Wales Cardiff, P.O. Box 915, Cardiff CF1 3TL, UK b Fossil Fuels and Environmental Geochemistry Postgraduate Institute, School of Civil Engineering and Geosciences and Centre for Molecular Ecology, University of Newcastle, Newcastle upon Tyne NE1 7RU, UK Received 23 January 2004; received in revised form 22 July 2004; accepted 20 October 2004 Available online 8 December 2004 Abstract Studies of the land disposal of biosolids and municipal sewage have focused largely on the potential pollution of the soil with pathogens, toxic compounds or heavy metals. Little is known about the impact of sludge amendment on carbon source and sink concentrationsinsoils.InthisstudygasconcentrationsinScottishsoilcores(fromlimedandunlimedplots)weremonitoredcon- tinuously at 3cm depth before, during and after sludge application using membrane inlet mass spectrometry (MIMS). Following sludge application to soil cores, significant and sustained increases in CH 4 (for 8 days) and CO 2 (for between 16 and 120 days) concentration were observed. This suggested short-term stimulation of indigenous methanogens, provision of a new methanogenic inoculum, or inhibition of methane oxidizers (for example by heavy metals or NH 4 in sludge). Soil microbial fermentative activity was enhanced over periods of a few months as shown by elevated CO 2 concentrations. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Membrane inlet mass spectrometry; Soil; Sewage sludge; Lime; CH 4 ;CO 2 1. Introduction TheEUgeneratesapproximately14milliontonnesof organicwasteeachyear(Albiachetal.,2000)andthereis a requirement for the development and optimisation of environmentally sound methods for its disposal. There are numerous governmental edicts concerning the fate of sewage sludge, or biosolids, resulting from municipal wastewater treatment in the UK and throughout Eur- ope. These include EU directives on the use of sewage sludge in agriculture (86/278), on surface water abstrac- tion(75/440)andondangeroussubstances(91/271).Per- haps the most significant, the Urban Waste Water Treatment Directive (91/271) and the Bathing Water Directive (76/160), resulted in the pronouncement of an EUbanonthedumpingofsewageatseafromtheend of1998.Withanapplicationrateof732,000drytonnes sewage per annum predicted for the UK in 2005/2006 (Christiansen, 1999) accurate assessment of the impact ofitsapplicationtosoilisessential.Manycontemporary studies have focused on the potential for pollution of agricultural land with pathogens (Dumontet et al., 1999;LewisandGattie,2002;Pillaietal.,1996),toxicor- ganiccompounds(Gelbertetal.,1992;WangandJones, 1994) or heavy metals (Alloway and Jackson, 1991; Baath, 1989; Bolan and Duraisamy, 2003; Raven and Loeppert, 1997). Such studies, however, may overlook the effect of soil amendment upon below ground gas dynamicsthatdrivegasemissionsintotheatmosphere. Theapplicationofsewagesludgetograsslandecosys- tems can have a profound effect on soil biogeochemical 0960-8524/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.biortech.2004.10.006 * Corresponding author. Tel.: +44 2920 875784; fax: +44 2920 874305. E-mail address: sheppardsk1@cardiff.ac.uk (S.K. Sheppard). Bioresource Technology 96 (2005) 1103–1115