Volatile organic compounds in the surface waters of a British estuary. Part 1. Occurrence, distribution and variation

The occurrence and temporal distribution of volatile organic compounds (VOC) in the Southampton Water estuary located on the coastline of central southern England was studied over two periods including 1987/1988 and 1995. VOC with volatilities of low to medium polarity ranging broadly from those of n-butane to n-octadecane were the major focus of interest. Over 100 individual compounds were routinely found in the larger, semi-industrialised estuary (Southampton Water) which is most subject to urban and industrial influences. The types and concentrations of VOC identified reflect the juxtaposition of both anthropogenic and biogenic influences. In Southampton Water, the most abundant VOC classes consisted of aromatic, alkanes, alkenes, cycloalkanes, cycloalkenes and chlorinated compounds. Some of the alkene VOC were present as terpenes and were derived from both marine and terrestrial sources. The distribution of biogenic VOC in Southampton Water was significantly influenced on a seasonal basis, and characterised by biogenic as well as anthropogenic sources. Marine phytoplankton (e.g. particularly the photosynthetic ciliate Mesodinium rubrum) exhibited a major influence on the character and distribution of VOC within summer months.