Scanning Microscopy


Samples of Anabaena spiroides were collected from a eutrophic freshwater lake (Rostherne Mere, Cheshire) during the bloom periods of 1988 and 1989, and analysed by SEM electron probe X-ray microanalysis. Vegetative cells, akinetes and heterocysts consistently had clear peaks of Mg, Si, P, S, Cl, Kand Ca.

In comparison to vegetative cells, akinetes had generally higher elemental mass fractions (particularly K and P) while heterocysts had significantly lower levels of Mg, P, and Ca.

For both years, elemental mass fractions in vegetative cells showed significant changes during the course of the bloom, but these were not consistent from one year to the next. Mass fractions showed no correlation with water concentrations in 1988, but positive correlations - particularly with P and K occurred in 1989. In 1989, the availability of Pin the lakewater was probably less than in 1988.

Significant correlations also occurred between certain elements within X-ray emission spectra, suggesting that specific associations occur in the cell.

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