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Lookup NU author(s): Professor John Pethick
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Understanding the patterns of marsh growth has primarily been based on modeling. Empirical verifications of such models are difficult. This is attributed to the inability of available techniques to generate past annual accretion rates from marsh sediment cores and the need for an extremely long observation period if a set of present day accretion rates is to be collected and used for such a purpose. Hypothetically, the large variation in temperature between summer and winter, occurring on some salt marshes, affects the viscosity of the tidal waters inundating and consequently the characteristics of the sediments deposited on the marsh surface. The variability of characteristics between seasonally deposited sediment can be used as annual markers to derive annual accretion rates. Sedimentation experiments at various temperatures and detailed analyses of core sediments, cut at 1 mm. intervals, from two selected Humber marshes, were conducted to test the hypothesis. The sedimentation experiments showed that sediment skewness, a sedimentological characteristic used to indicate the symmetry of the sediment distribution curve about the mean, is most sensitive to variations in water temperature and can be used as annual markers in marsh sediments. Detailed sedimentological analyses of two Humber marsh cores showed skew variability follows a low magnitude cyclicity throughout both cores. Using a 3 year time lag period and the negative skew peaks as annual markers, correlation between a set of peak negative skew values, occurring within a dated section of the core, and the average summer field temperatures was found to be statistically significant. The period for sediment to accumulate within the dated section was calculated to equal the period derived from the dateable pollutant horizons respectively. Additionally, the annual accretion rates derived using the negative skew peaks as annual markers are comparable to the observed average annual accretion rates previously reported.
Author(s): Mohd-Lokman H, Pethick JS
Publication type: Article
Publication status: Published
Journal: Wetlands Ecology and Management
Print publication date: 01/01/2001
ISSN (print): 0923-4861
ISSN (electronic): 1572-9834
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