Sources of organic nitrogen, phosphorus and carbon in antarctic streams

Abstract

Dissolved and particulate organic materials were analysed in 14 streamwaters of the McMurdo Sound region of Antarctica. These streams are fed by glacial meltwaters and pass through catchments largely devoid of terrestrial vegetation. Nonetheless they contained measurable amounts of organic material in both dissolved and particulate form. Most of the dissolved organic carbon (DOC) values lay in the range 1–3 g C m⁻³. Higher values were recorded close to penguin rookeries on the coast. Dissolved organic nitrogen (DON) concentrations were generally two orders of magnitude less than DOC and in flowing waters with rich blue-green algal growth DON increased with distance downstream. Dissolved organic phosphorus levels were generally much lower than DON, but highly variable. Particulate organic carbon concentrations (both fine and coarse) were unexpectedly high. Five sources of organic matter were identified: birdlife (only near the coast), autochthonous algal production (especially important for DON), streambed soils (important at first flows), lacustrine and marine sediments, through which certain streams and glaciers cut, and the glacial ice, which received organic input from wind-blown particulates, snowfall and the underlying bedrock of sedimentary origin. Highest organic levels were recorded in the first melt down the glacier face, suggesting that winter deposition of organic materials may be especially important.