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[1] Little is known about nitrous oxide (N 2 O) emissions from wild animal colonies. N 2 O fluxes were measured from a penguin colony on Ardley Island, a seal and skua colony on Fildes Peninsula in the maritime Antarctic using a static chamber technique. Mean fluxes from penguin, skua and seal colonies were 856, 132 and 189 mg N 2 O-N m À2 h À1 , respectively. The deposition of sea animal excreta controls spatial variations of N 2 O fluxes from the colonies. The highest fluxes (2559, 2836 and 2081 mg N 2 O-N m À2 h À1 for penguin puddles, seal wallows and skua puddles, respectively) occurred during the freezing-thawing period. Laboratory experiments showed that the freezing-thawing cycle induced a flush of N 2 O from the soils sampled from the colonies and denitrification was the predominant process for the N 2 O source. We proposed that sea animal colonies represent the strong point sources of N 2 O in the maritime Antarctic.

[1] Most studies on greenhouse gas emissions from animals concentrated on domestic animals, with limited data available from wild animals. The number of marine animals is potentially large in coastal Antarctica. In this paper, N 2 O and CH 4 emissions were investigated from a penguin colony, a seal colony, a skua colony, the adjacent animal-lacking tundra, and background tundra sites to test the effects of marine animals on their fluxes in maritime Antarctica. ) are much higher than those from the animal-lacking tundra, whereas the background tundra showed negligible N 2 O fluxes. Penguin puddles and seal wallows were stronger CH 4 emitters than animal colony tundra soils, while animal-lacking tundra soils were strong CH 4 sinks. Overall high N 2 O and CH 4 emissions were modulated by soil physical and chemical processes associated with marine animal activities: sufficient supply of the nutrients NH 4 + -N and NO 3 À -N, total nitrogen, and total organic carbon from marine animal excreta, animal tramp, and high soil water-filled pore space. Laboratory incubation experiments further confirmed that penguin and seal colony soils produced much higher N 2 O and CH 4 emissions than animal-lacking tundra soils. Our results indicate that marine animal colonies are the hot spots for N 2 O and CH 4 emissions in maritime Antarctica, and even at the global scale, and current climate warming will further increase their emissions.

Earlier reports show very low concentrations of phosphine in remote air of the lower troposphere of nonpolar regions, in the low ng m(-3) range during the night and in the pg m(-3) range during daylight around noon. In this study, abnormally and unexpectedly high phosphine concentrations (30.0-407.8 ng m(-3), 11 locations) were found in polar air samples collected on Millor Peninsula, eastern Antarctica and Fildes Peninsula, western Antarctica. The maximum concentration was measured in the atmosphere of penguin colonies. Field phosphine emission rates from four colonies were 8.99 ng m(-2) h(-1) (skua colony), 9.56 ng m(-2) h(-1) (gentoo penguin colony), 39.96 ng m-2 h-' (seal colony) and 63.58 ng m(-2) h(-1) (empire penguin colony), respectively. Our air sampling sites are located downwind of two large penguin colonies, indicating that penguin colony emission is the predominant source for atmospheric PH3 on Millor Peninsula. Laboratory scale incubation of ornithogenic soils amended by penguin guanos yielded a maximum PH3 production rate of 0.58 ng kg(-1) d(-1) specifically at low temperature (4 degrees C). Significant concentrations of phosphine occur in the atmosphere of coastal Antarctica and confirm the existence of a small gaseous link in the phosphorus cycle of the Antarctic tundra ecosystem.