210Po/210Pb Disequilibria and Its Estimate of Particulate Organic Carbon Export Around Prydz Bay, Antarctica

• Published in: Frontiers in Marine Science
• Main Authors: Hu, Huina, Liu, Xiao, Ren, Chunyan, Jia, Renming, Qiu, Yusheng, Zheng, Minfang, Chen, Min
• Other Authors: Chinese Arctic and Antarctic Administration, Foundation for Innovative Research Groups of the National Natural Science Foundation of China, China Ocean Mineral Resources Research and Development Association
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Frontiers Media SA 2021
• Subjects: Antarc*; Antarctica; Prydz Bay; Southern Ocean
• Online Access: http://dx.doi.org/10.3389/fmars.2021.701014; https://www.frontiersin.org/articles/10.3389/fmars.2021.701014/full

Due to the remoteness and difficulty of sampling, the 210 Po and 210 Pb data are scarce in the Southern Ocean. Here, the activity concentrations of 210 Po and 210 Pb around Prydz Bay in austral summer were determined to understand their spatial variation and evaluate the dynamics of particle organic matter (POM). The activity concentrations of dissolved 210 Po (D 210 Po) and 210 Pb (D 210 Pb) range from 0.47 to 3.20 Bq⋅m –3 and from 1.15 to 2.97 Bq⋅m –3 , respectively, with the lower values in the shelf. The particulate 210 Po (P 210 Po) and 210 Pb (P 210 Pb) are lower in the open ocean and increase to the coastal waters, among which the circumpolar deep water (CDW) is the lowest. The activity concentration of total 210 Pb (T 210 Pb) ranges from 1.26 Bq⋅m –3 to 3.16 Bq⋅m –3 , with a higher value in CDW, which is ascribed to radiogenic production from 226 Ra and subsequent lateral transport. Occasionally a high value of T 210 Po occurs in deep water (>3.00 Bq⋅m –3 ), which may be caused by the remineralization of POM. The disequilibria between T 210 Po and T 210 Pb appears throughout the water column at most stations. The average T 210 Po/T 210 Pb) A.R. in the euphotic zone is 0.66, reflecting the effect of strong particle scavenging. There is a good positive correlation between the solid-liquid ratio of 210 Po and POC, while 210 Pb does not, indicating that particulate organic matter regulates the biogeochemical cycle of 210 Po around Prydz Bay. Based on the 210 Po/ 210 Pb disequilibria, the export flux of POC in the water column is estimated to be 0.8–31.9 mmol m –2 d –1 , with the higher values in the shelf.