Sedimentological archives of coastal storms in South-West Wales, UK

High magnitude coastal storms have persistently threatened human communities and environments. In the British Isles their frequency and magnitude are predicted to increase in the future with advancing climate change. This study analyses sedimentological evidence from south-west Wales to assess the impacts of high magnitude coastal storms in vulnerable coastal saltmarshes in the Three Rivers Estuarine Complex, Carmarthen Bay. Storm surge saltmarsh deposits were identified following geochemical and particle size analyses and dated using radionuclides ¹³⁷Cs and ²¹⁰Pb. The sedimentological evidence is compared with regional tidal gauge and meteorological records to assess variability in storm recording and corroborate the storms which produced the sedimentological deposits. Three episodes of high magnitude saltmarsh storm surge deposition are identified in 1954, 1977 and 1981. Evidence of storm erosion or alternative forms of storm deposition were not present. The sedimentological evidence highlights the comparative rarity of major depositional events in the saltmarshes between 1929 and 2019. The recorded depositional events combined with organic accretion have contributed to maintaining saltmarsh elevation relative to sea level. There remains uncertainty surrounding the storm impacts on the saltmarshes of the Three Rivers Estuarine Complex. When the future 21st century threats of increasing regional atmospheric storminess and sea level rise are considered along with predictions of saltmarsh degradation, this study suggests further research is required to explore the sedimentological storm impacts. This could contribute to sustaining the vulnerable coastal saltmarsh environments and the important ecosystem services they provide

ITRAX Core Scanner Capabilities Combined with Other Geochemical and Radiochemical Techniques to Evaluate Environmental Changes in a Local Catchment, South Sydney, NSW, Australia

In this study, geochemical and radioanalytical techniques are used together with the ITRAX core scanner to reconstruct the environmental history of Mill Creek catchment, located on the south-western fringes of Sydney. This ITRAX capability study was undertaken to investigate environmental changes in a local catchment which incorporates a nuclear research reactor, a small legacy nuclear waste burial ground, extensive new housing developments, a large rubbish tip, as well as quarries. This catchment changed from being near pristine in the 1950’s to an extensively developed catchment with wide ranging land uses. This rapid development has led to silting up near the mouth of the creek, and there is also evidence of periodic siltation triggered by catchment disturbance from local bushfires, associated with peaks in magnetic susceptibility. The sedimentary environment changed from a creek system to a mangrove swamp and saltmarsh. Changes in Cu, Zn and Pb distributions over the last 60 years suggest an anthropogenically-driven input, although concentrations measured by WD-XRF indicate that the level of urbanisation is lower in the study area than in many of the more industrialised and urbanised neighbouring catchments of Sydney estuary and Botany Bay. The activities of 239 + 240Pu and 241Am in the sediment are below detection limit, which strongly suggests that the legacy nuclear waste has not entered the creek system. © 2015, Springer