ISSN:
1573-5117
Keywords:
paleolimnology
;
caesium-137
;
perched lake
;
meromictic
;
diffusion
;
bioconcentration
;
sediment accumulation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Hidden Lake is a perched, brown-water lake located in the centre of Great Sandy Island (Fraser Is.), S.E. Queensland. It is highly acid (pH 4.0), oligotrophic and is thermally and chemically stratified for most of the year. The sediments revealed a 137Cs profile which departed from the temporal pattern of 137Cs fallout in Brisbane and was represented by an exponential increase of 137Cs towards the surface sediments from ca. 32 cm depth. The possible causes of the divergent profile are discussed, including physical and biological mixing, lag in the transport of catchment material to the sedimentary basin, diffusion, recycling and biological concentration. It is hypothesised that a combination of the last four processes, with diffusion facilitated by the highly acid conditions, are the major causes of the observed 137Cs profile. Possible recycling and bioconcentration of 137Cs raises questions as to the validity of this method of dating in similar environmental conditions, and as to the interpretation of other palaeochemical data. These hypotheses are to be tested against profiles obtained from 14C, 210Pb, 239/240Pu analyses of the sediment, and the measurement of 137Cs activity in the water and biota of the lake.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00028423
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