Methyl Chloride and Methyl Bromide Production and Consumption in Coastal Antarctic Tundra Soils Subject to Sea Animal Activities

• Published in: Environmental science & technology Vol. 54; no. 20; pp. 13354 - 13363
• Main Authors: Zhang, Wanying, Jiao, Yi, Zhu, Renbin, Rhew, Robert C.
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 20.10.2020
• Subjects: Anaerobic treatment; animal manures; Animals; Antarctic region; Antarctic Regions; Antarctica; Bromine; Chlorides; Chlorine; Colonies; Consumption; Dung; excreta; Guano; highlands; Hydrocarbons, Brominated; Marshes; Methyl bromide; Methyl chloride; Methyl Chloride - analysis; Ozone; penguins; Polar environments; seals; Soil; Soil moisture; Soil temperature; soil water; Soils; Stratosphere; Taiga & tundra; Temperature gradients; Troposphere; Tundra; tundra soils; Antarctic Regions; Antarctica; Antarctic region
• ISSN: 0013-936X; 1520-5851; 1520-5851
• DOI: 10.1021/acs.est.0c04257

Methyl chloride (CH Cl) and methyl bromide (CH Br) are the predominant carriers of natural chlorine and bromine from the troposphere to the stratosphere, which can catalyze the destruction of stratospheric ozone. Here, penguin colony soils (PCS) and the adjacent tundra soils (i.e., penguin-lacking colony soils, PLS), seal colony soils (SCS), tundra marsh soils (TMS), and normal upland tundra soils (UTS) in coastal Antarctica were collected and incubated for the first time to confirm that these soils were CH Cl and CH Br sources or sinks. Overall, tundra soil acted as a net sink for CH Cl and CH Br with potential flux ranges from -18.1 to -2.8 pmol g d and -1.32 to -0.24 pmol g d , respectively. The deposition of penguin guano or seal excrement into tundra soils facilitated the simultaneous production of CH Cl and CH Br and resulted in a smaller sink in PCS, SCS, and PLS. Laboratory-based thermal treatments and anaerobic incubation experiments suggested that the consumption of CH Cl and CH Br was predominantly mediated by microbes while the production was abiotic and O independent. Temperature gradient incubations revealed that increasing soil temperature promoted the consumption of CH Cl and CH Br in UTS, suggesting that the regional sink may increase with Antarctic warming, depending on changes in soil moisture and abiotic production rates.