Reconnaissance limnology of Sub-Antarctic islands. II. Additional features of the chemistry of Macquarie Island lakes and tarns

Abstract

Further analyses of waters from lakes and tarns on Macquarie Island, including some not previously sampled, confirm conclusions of an earlier survey. Oceanic spray is a principal source of ions. Geochemical influence is minimal in most lakes, but Square Lake and Waterfall Lake contain considerably more calcium than others and the cationic dominance order is changed from that of seawater. Skua Lake is similarly affected though calcium concentrations are not so markedly increased. Magnesium enrichment does not occur.

Though calcium and bicarbonate accrue in approximately equivalent amounts, more lakes are deflected from seawater anionic dominance order than the three with changed cationic orders. Despite equivalent accession of calcium and bicarbonate, Square Lake and Waterfall Lake occupy anomalous positions on a plot of calcium proportions against Oceanic Origin Factor.

Seasonal variation in chemical composition is slight, but is greatest in Waterfall Lake and least in the shallow Square Lake where perhaps buffering by sediments is involved. Atmospheric supply of oceanic ions is commonplace on Sub-Antarctic islands.