Potential ammonia emissions from penguin guano, ornithogenic soils and seal colony soils in coastal Antarctica: Effects of freezing-thawing cycles and selected environmental variables

Very little attention has been paid to quantifying ammonia (NH3) emissions from Antarctic marine animal excreta. In this paper, penguin guano and ornithogenic soils from four penguin colonies and seal colony soils were collected in coastal Antarctica, and laboratory experiments were conducted to investigate potential NH3 emissions and effects of environmental factors on NH3 fluxes. Ammonia fluxes were extremely low from the frozen samples. Significantly enhanced NH3 emissions were observed following thawing. The mean fluxes were 7.66 +/- 4.33 mg NH3 kg(-1) h(-1) from emperor penguin guano, 1.31 +/- 0.64 mg NH3 kg(-1) h(-1) from Adelie penguin guano and 0.33 +/- 0.39 mg NH3 kg(-1) h(-1) from seal colony soils during the thawing period. Ammonia emissions from penguin guano were higher than those from ornithogenic soils during freezing-thawing cycles (FTCs). The temperature, pH, total nitrogen (TN) and drying-wetting conversion had an important effect on NH3 fluxes. For the first time, we provide a quantitative relationship between NH3 flux and temperature, TN and pH. Our results show that marine animal excreta and ornithogenic soils are significant NH3 emission sources. In coastal Antarctica, FTC-induced NH3 emissions might account for a large proportion of annual flux from marine animal colonies due to high freezing-thawing frequency.