Biogeochemical features of hydrocarbons in cyanobacterial mats from the McMurdo Dry Valleys, Antarctica

Hydrocarbons in 9 cyanobacterial mat samples from the Labyrinth ponds and Lake Canopus in the Wright Valley of the McMurdo Dry Valleys in southern Victoria Land, Antarctica were studied to clarify their features in relation to source organisms and biogeochemical significance. The major hydrocarbons in cyanobacterial mats were all alkenes, such as n-C sub(17:1) (total carbon number per molecule:number of double bonds), 3-, 4- and 5-methyl-C sub(18:1), n-C sub(18:1), 3-methyl-C sub(19:1), 5-methyl-C sub(20:1) and/or hop-22(29)-ene. These hydrocarbons are mainly produced by cyanobacteria, such as Phormidium spp. which are major organisms of the cyanobacterial mats. The predominance of alkenes is probably ascribed to the influence of extremely low air temperatures in Antarctica. Cyanobacterial mats may be important sources of organic components in lakes and ponds in the McMurdo Dry Valleys, and other inland aquatic environments in Antarctica.