Selenium volatilization from tundra soils in maritime Antarctica

Authors: YE, WENJUAN - Hefei University Of Technology; YUAN, LINXI - Jiaotong University; ZHU, RENBIN - Hefei University Of Technology; YIN, XUEBIN - University Of Science And Technology Of China; Banuelos, Gary

Submitted to: Environment International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2020
Publication Date: 10/30/2020
Citation: Ye, W., Yuan, L., Zhu, R., Yin, X., Banuelos, G.S. 2020. Selenium volatilization from tundra soils in maritime Antarctica. Environment International. 146. Article 106189. https://doi.org/10.1016/j.envint.2020.106189.
DOI: https://doi.org/10.1016/j.envint.2020.106189

Interpretive Summary: It is well-known that maritime Antarctica harbors a potentially large number of sea animals, including penguins and seals. As a result, there is a large amount of penguin guano deposited into terrestrial ecosystems, which is particularly rich in organic carbon and trace elements like selenium (Se). The biological methylation and subsequent volatilization of Se to the atmosphere may be one of the most important processes of the Se biogeochemical cycling in terrestrial ecosystems in the Antartica. In this study, we collected soils from penguin colonies, seal colonies, adjacent tundra, tundra marshes and normal tundra in maritime Antarctica during the 31th Chinese Antarctic Research Expedition. In the laboratory, we investigated Se speciation and volatile Se produced from these Antarctic soils using gas-trapping methods. Our results showed that most soil Se was found as organically bound Se. In addition, we measured an increase in gaseous Se produced from these soils as they thawed. These results indicate that gaseous Se emitted from soils inhabited by sea animal colonies might be transported through the atmosphere, and then deposited into accumulated snow or ice. Volatilization of Se might initially decrease deposited Se level in sea animal colony soils, but the atmospheric movement and deposition of gaseous Se into adjacent tundra soils will likely occur. Since the Antarctic region is highly sensitive to global climate warming, an increase in temperature might further increase production of gaseous Se volatilization and lead to increases of Se deposition. Hence, this study is helpful for better understanding the potential effect that a warming climate may have on the biogeochemical cycle of gaseous Se and Se accumulation in tundra soils located in maritime Antarctica.

Technical Abstract: Maritime Antarctica harbors many penguins and seals that may contribute considerable selenium (Se) into terrestrial ecosystems originating from their guano. The source of Se in neighboring tundra soils may have originated via biomethylation and volatilization processes affecting Se contained within the guano complex. To determine and quantify Se in soil and in volatile Se emissions, Se speciation analyses were initiated for the first time in penguin colony soils (PCS), tundra marsh soils (TMS), seal colony soils (SCS), tundra soils (STS), and normal tundra soils (NTS) collected in Maritime Antarctica. The collected soil were incubated and evaluated for Se content using gas-trapping methods under laboratory conditions. The total Se content in PCS, SCS, STS and TMS was predominately organic matter-bound Se for all soils. There was one order of magnitude higher Se content in all soils compared to Se content in NTS. Volatilization of Se was also measured and rates were greatest in PCS and followed by SCS. The thawing of all frozen soils resulted in a 2-5-fold increase in volatile Se and the rate continued to increase until the soils were fully thawed. Overall, volatile Se was 1.5-4.1 times higher from fully-thawed tundra soils than those from thawing soils. The volatile Se values ranged from 0.11 to 0.20 µg kg/d during a five-day soil incubation. There was also significant positive correlation with volatile Se and soil temperature. Speciation of volatile Se showed that the methylated species were dominated by dimethylselenide (DMSe) in PCS and dimethyldiselenide (DMDSe) in SCS. Our results suggest that inputs of Se originating from penguin and seal guano in combination with climate warming, freezing-thawing processes in the soil, may promote Se volatilization and result in the movement and eventual deposition of volatile Se into nearby tundra soils. Hence, the biomethylation and volatilization of Se from guano-rich soils inhabited by sea animal colonies may play a significant role in the biogeochemical cycling of Se in maritime Antarctica.