Spatial and temporal variability of biogenic isoprene emissions from a temperate estuary

• Published in: Global biogeochemical cycles Vol. 26; no. 2
• Main Authors: Exton, D. A., Suggett, D. J., Steinke, M., McGenity, T. J.
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 01.06.2012; American Geophysical Union
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Atmosphere; Biological and medical sciences; Biosphere; Earth sciences; Earth, ocean, space; estuary; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; General aspects; Geobiology; Geochemistry; isoprene; Limnology; seasonality; Synecology; trace gas; VOC; United Kingdom; Europe; Western Europe; Availability; Night; Environmental factor; concentration; variability; tides; Phytobenthos; drill cores; Biogenic factor; Intertidal zone; Light; temperature; estuaries; Community; sediments
• ISSN: 0886-6236; 1944-9224
• DOI: 10.1029/2011GB004210

Isoprene is important for its atmospheric impacts and the ecophysiological benefits it affords to emitting organisms; however, isoprene emissions from marine systems remain vastly understudied compared to terrestrial systems. This study investigates for the first time drivers of isoprene production in a temperate estuary, and the role this production may play in enabling organisms to tolerate the inherently wide range of environmental conditions. Intertidal sediment cores as well as high and low tide water samples were collected from four sites along the Colne Estuary, UK, every six weeks over a year. Isoprene concentrations in the water were significantly higher at low than high tide, and decreased toward the mouth of the estuary; sediment production showed no spatial variability. Diel isoprene concentration increased with light availability and decreased with tidal height; nighttime production was 79% lower than daytime production. Seasonal isoprene production and water concentrations were highest for the warmest months, with production strongly correlated with light (r2 = 0.800) and temperature (r2 = 0.752). Intertidal microphytobenthic communities were found to be the primary source of isoprene, with tidal action acting as a concentrating factor for isoprene entering the water column. Using these data we estimated an annual production rate for this estuary of 681 μmol m−2 y−1. This value falls at the upper end of other marine estimates and highlights the potentially significant role of estuaries as isoprene sources. The control of estuarine isoprene production by environmental processes identified here further suggests that such emissions may be altered by future environmental change. Key Points Estuarine isoprene shows significant spatial, diurnal, and seasonal variation Estuarine isoprene was driven primarily by environmental factors Temperate estuaries are important sources of coastal biogenic isoprene