Emissions of volatile organic compounds originating from UK livestock agriculture

In this paper we estimate the quantity of non-methane volatile organic compounds (NMVOCs) emitted from UK livestock. The final estimate is derived from published values and from direct measurements of NMVOC emissions from dairy cattle slurry and laying hen manure. Emission rates of NMVOCs were determined for fresh dairy cattle slurry and laying hen manure using a 40 m^3 emissions chamber. Dimethyl sulphides dominated emissions from laying hen manure at 753 ± 263 g m^-3 day^-1. Emissions from dairy cattle slurry were dominated by volatile fatty acids (C2-C5, 6.3 ± 3.1 g m^-3 day^-1) and phenols (2.4 ± 1.2 g m^-3 day^-1). Many of these NMVOCs are decomposition products from protein sources from which ammonia is also a by-product. There is a close association between ammonia and NMVOC production from manure, and on this basis we estimated the annual NMVOC emissions from UK livestock as 165 ± 56 kt for 2002. These emissions compare to those from the larger industrial and transport sectors and exceed the 50-100 kt C year^-1 currently determined as originating from biogenic sources including agriculture. These findings have implications for air quality, and these NMVOCs may affect the cleansing capacity of the troposphere.