Distribution of enteric bacteria in Antarctic seawater surrounding a sewage outfall

Abstract

The spatial distribution and movement of the sewage plume from McMurdo Station, Antarctica, was investigated in the ocean under the early summer sea ice. Ocean currents were also examined to determine their effect on the movement of the plume. Samples of sea water were obtained via holes drilled through the ice and analyzed for coliform bacteria. Coliform densities in ice cores were also determined. Densities of coliform bacteria as high as 10 5/100 ml were found along the c. 1 km shoreline of McMurdo Station and the plume extended 200–300 m seaward. The relocation of the outfall from a surface configuration to the subsurface (11 m deep) had little influence on the distribution of the plume that sometimes reached the seawater intake station, 400 m to the south. Ocean current measurements in the study area confirmed that, while the prevailing advection was to the north and away from the intake area, episodic reversals of flow at some current meter stations coincided with pulses of sewage that moved to the intake. These findings support the use of bacterial indicators as one means to map the distribution and movement of recent sewage contamination in cold (−1.8°C) sea water and provide evidence that the disposal and movement of domestic wastes deserves attention in costal polar environments.