Apparent Absence of Microbial Life inside an Alkaline Slag Dump
An extremely alkaline slag dump in Germany was investigated for its mineralogy and colonization with microorganisms. The dump material originated from a metallurgical processing plant for steel production and consisted of a magnetic concentrate of cohenite, metallic iron and magnetite interwoven or associated with various slag related phases such as glasses of variable chemistry, RO-, C2F- and C4AF- phases, and phases originating from the ovens, steel additives, sand and construction fragments. After deposition, reactions in the surface layer generated a number of secondary phases such as gels (NaCO3-rich or -poor), calcite, mirabilite, natron, and others. To explore the microbiology inside the approximately 15 m high dump, 35 samples were taken over the whole depth range via core drilling. Total cell counts were determined via acridine orange staining and living cells were enumerated on R2 agar plates for heterotrophs. Both methods allowed for the detection of microbial life on the dump surface down to about 1 m depth. In this depth range the pH values were between 8 and 12. Below, microbial life was not detected, most likely because of the high pH values of 12 and the low availability of organic carbon inside the dump. In contrast to all previously studied sulfidic dumps the interior of the alkaline slag dump did not appear to be a habitat for microorganisms.
M. Zaki Mubarok, Siti Khodijah Chaerun, Wahyudin Prawira Minwal, Fadhli Muhammad and Killang Pratama
A. Schippers and D. Rammlmair, "Apparent Absence of Microbial Life inside an Alkaline Slag Dump", Advanced Materials Research, Vol. 1130, pp. 93-96, 2015