Geochemical phases and stability of metal contaminants in intertidal sediments of the Severn Estuary

Project: Research


The media frequently present stories concerning the implications of sea level rise and threats to society, particularly inhabitants of low-lying areas, of ‘natural’ processes such as coastal erosion and land loss. Less frequently reported, but just as real, are the indirect consequences of this erosion in environments rich in contaminants, such as estuaries. Consequences include the release of stored contaminants held within these eroded sediments, back into the water body. This apparent lacuna is the focus of this RSF application and will entail both scientific and social scientific evaluation.

Previous work has determined total levels and depth variation of selected contaminants, present in salt marsh sediments of different ages in the Severn estuary. Given the key environmental issues of marsh erosion brought on by sea level rise and the increased frequency of south-westerly winds which drive erosion in the Severn Estuary, a key need is to understand the impact that these contaminants will have when they are reintroduced into the estuarine environments. Marsh erosion and/or geochemical alteration are critical factors in shaping changing environmental conditions. In order to do this, it is important to know in which chemical phase the contaminants are present. The mineral phase can be considered as environmentally stable, but other chemical phases are environmentally active and potentially bioavailable, and hence a potential threat to water quality and ultimately, the estuarine food chain.

Thus, this project will investigate one marsh area with a known accretion history. The age of these sediments post dates the 1930’s but the project will provide the ability to assess the potential of broadening the work to include other marsh units in the Severn, where accretion history spans much longer time periods. Although restricted to one of many marsh areas available, the design of this initial data gathering project will not only provide key information in support of future grant applications, but it will also be used to produce a publication in its own right.

Effective start/end date1/06/10 → …

ID: 21707117