Year-long measurements of C1-C3 halocarbons at an urban background site and their correlation with meteorological parameters

The mixing ratios of fourteen ozone-depleting, long lived C1-C3 halogenated compounds have been measured over the period from October 2004 to December 2005 at an urban background monitoring site in Bristol, UK. These halocarbons have been measured using a GC-twin linked ECD system. Time series and seasonal variations of the halocarbons were analysed over the period to determine where possible potential biogenic and anthropogenic sources and sinks. Correlations between the target halocarbons were also observed, suggesting common sources within the area. Wind rose plots for all halocarbons have been used to assist in the determination of halocarbons sources. Such an analysis suggests that the Severn Estuary, a wetland area in Bristol with the second highest tidal range in the world, could be a possible source of some biogenic halocarbons and also a sink. Avonmouth, an industrial site in Bristol, with heavy industries and several small refuse sites has been identified as a potential source of anthropogenically derived halocarbons. The relationship between halocarbon concentration and wind speed has been investigated; revealing unusual results for CH3Br. The result also suggests that the meteorological effect is only applicable to compounds which have significant local emission within the Bristol Area.