H2O2 accumulation from photochemical production and atmospheric wet deposition in Antarctic off-shore waters of Potter Cove, King George Island, South Shetland Islands.

ABELE, D., FERREYRA, G.A., SCHLOSS, I.

ANTARCTIC SCIENCE

CAMBRIDGE UNIV PRESS

Año: 1999 p. 131 - 139

0954-1020

Temporal and spatial variations of the hydrogen peroxide accumulation were measured in off-shore waters and in intertidal rockpools near Jubany Station, King George Island, South Shetland Islands. As H,O, photoformation is mainly driven by the short wavelength radiation in the UV-B and the UV-A range of the solar spectrum, the study was conducted between the beginning of October and the end of December 1995, the period of Antarctic spring ozone depletion. Wet deposition of H,O, containing snow was identified as a major source of hydrogen peroxide in the surface waters of Potter Cove. As the concentrations of issolved organic carbon (DOC) in Potter Cove surface waters were low ( 12 I * 59 pmol C 1-I), when compared to the highly eutrophicated waters on the German Wadden coast (6000-7000 pmol C 1-I), direct UV-induced DOC photo-oxidation was of only limited significance in the Antarctic sampling site. Nonetheless, under experimental conditions, H,O, photoformation in Potter Cove surface waters amounted to 90 & 40 nmol H,O, h-? I-? under a UV-transparent quartz plate. When high energy UV-B photons were cut-off by a WG320 filter formation continued at a rate of 66 29 nmol H,O, h-? I-? due to UV-A and visible light photons. Samples from freshly deposited snow contained between 10 000 and 13 600 nmol H,O, I-?, and a snowfall event in mid November resulted in a maximum concentration of 1450 nmol H,O, 1.? in the upper I0 cm layer of Potter Cove surface waters. Maximal H,O, concentrations in intertidal rockpools were even higher and reached up to 2000 nmol H,O, 1.? after the snowfall event. During a grid survey on December 17 1995, H,O, concentrations and salinity displayed a north to south gradient, with higher concentrations and PSU at the south coast of the cove. The reasons for this spatial inhomogenety are as yet unknown, but may relate to a minor local input of photo-reactive organic matter from creeks entering the cove in the south-east, as well as to waste water discharge from the station, located on the south beach.