Coastal geochemists at BGS are studying how the sea level has varied over the past 10 000 years (Holocene). We are examining changes in the chemistry and isotopic composition of organic matter in modern intertidal sediments and deep sediment cores from the outer Humber Estuary, UK, as well as the Lincolnshire Marshes, UK.
We investigated the use of bulk stable carbon isotopes (δ13C) and the ratio of organic carbon to total nitrogen (C/N) to identify the main types of organic matter from high to low salt marsh as well as tidal flats. These data were then used to interpret the palaeoenvironmental changes (changes to the environment through the Holocene) contained within two sediment cores.
The Holocene δ13C values and C/N ratio suggested an overall change from terrestrial (land) to marine (sea) conditions. The estuary wide expansion of marine conditions from about 3300 years before present was followed by a contraction and return to estuarine conditions after about 2700 years before present (Lamb et al. 2007).
Sea-level rise is occurring globally at an average of approximately 3mm/yr. This change potentially threatens many of the world's most densely populated cities and ports including those in the UK. Predicting how quickly sea level will rise in the future is an important question, which needs to be underpinned by an improved understanding of how sea level has changed in the past.
Lamb, A.L., Vane, C.H., Rees, J.G., Wilson, G.P. and Moss-Hayes, V.L. 2007. Assessing δ13C and C/N ratios from stored organic material as Holocene sea-level and palaeoenvironmental indicators in the Humber Estuary, UK. Marine Geology 244, 109-128.
Contact Dr Christopher Vane for more information.