Potential hazards of metal-contaminated soils in an estuarine impoundment
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SEDIMENTS, SEC 1 • SEDIMENT QUALITY AND IMPACT ASSESSMENT • RESEARCH ARTICLE
Potential hazards of metal-contaminated soils in an estuarine impoundment Gillian A. Glegg 1 & Cally Barratt 1 & Alex Taylor 2 & Emily Gulson 1 & Geoffrey E. Millward 3 Received: 6 September 2020 / Accepted: 25 October 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Purpose A recreational impoundment was constructed in the mid-nineteenth century on the mudflats reclaimed from the Plym Estuary (SW England) following salt marsh removal and infilling with waste soils from local catchments. Restoration of the salt marsh was attempted about 25 years ago when a regulated tidal exchange system was installed in the embankment separating the impoundment from the estuary. Currently, the embankment is disintegrating with the potential loss of the impounded soils, of unknown composition, to the estuary. Methods Cores were obtained from the impoundment and the adjoining estuary, sectioned, dried and analysed. The geochronology of the soils, and estuarine sediments, was established using gamma-ray spectroscopy to determine the activities of fallout radionuclides, 137Cs and 210Pb. The concentrations of As, Co, Cr Cu, Fe, Mn, Ni, Pb, Rb, Sn, W and Zn in the core sections were determined by quantitative X-ray fluorescence spectrometry. Results Below a shallow surface layer (> 5 cm and post-1963), metal concentrations were high with several exceeding soil quality indices, and enrichment factors (EFs) were elevated, in the sequence Sn > W≈As > Cu > Pb. Estimates of the total masses of particulate Sn, Pb, As and Cu available for down-estuary migration were significant. Conclusions Given the ecotoxicological implications resulting from a loss of metal-contaminated soils into the estuary, a strategy for the future management of the impoundment is required. The conditions at this site are compared with ageing estuarine impoundments at other locations, where polluted sediments, or soils, could be vulnerable to release. Keywords Estuary . Impoundment . Managed realignment . Contaminated soils . Release
1 Introduction Estuarine salt marshes and coastal wetlands have been impounded for more than 200 years, mainly driven by a
human need to increase the land available for alternative uses, such as agriculture, urban development and recreation (Gedan et al. 2009). Salt marshes are dependent on regular tidal intrusions to retain their geomorphology and
Responsible editor: Elena Romano Supplementary Information The online version contains supplementary material available at https://doi.org/10.1007/s11368-02002821-x. * Geoffrey E. Millward [email protected] Gillian A. Glegg [email protected] Cally Barratt [email protected] Alex Taylor [email protected]
Emily Gulson [email protected] 1
School of Biological and Marine Sciences, Portland Square, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK
2
School of Geography, Earth and Environmental Sciences, Portland Square, University of Plymout
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