Archaea were detected in the BLM-1 well, but our analysis of 21,794 partial rRNA gene sequences generated by
pyrotag analysis showed that groundwater from this deep source (878 m) revealed absolutely no overlap at the species
level with archaeal sequences from any of the Ash Meadows springs. Thus, patterns of archaeal diversity indicate that
deep groundwater in BLM-1 well is not groundwater flowing along flow paths that supply Ash Meadows springs, even
though δ2
H and δ18O data indicate that they have the same recharge area sources. Likewise, bacterial libraries for the
BLM-1 well and the well at Nevares Spring, while being dominated by functionally similar populations (e.g. Firmicute
predicted sulfate reducers and Nitrospirae), do not share a single overlapping lineage at the species level. Thus, microbial
data fail to support a hydrologic connection across the Funeral Mountains between the BLM-1 well and the Furnace Creek
springs (the waters are not along the same flow path), even though a large fault system connects BLM-1 with the springs.
Rather, consistent with BLM-1 well’s high temperature (58o
C) and anaerobic condition, this water is more likely derived
from a heretofore unrecognized, isolated deep flow path. Thus, although the δ2
H and δ18O data show that the Ash
Meadows and Furnace Creek springs have the same recharge sources, our microbial data indicate that they do not follow
the same flow paths in the deep carbonate aquifer system. To the best of our knowledge, this study represents the first
systematic application of a combined microbial/biogeochemical/isotopic approach for inferring subsurface fluid flow at
the regional scale.