Environmental Engineering Reference
In-Depth Information
Figure 4.
Depth profile of water chemistry of hypersaline Mono Lake during meromixis in
August, 2001. Agarose gel shows amplification products of reverse-transcriptase polymerase
chain reaction (RT-PCR) of
nifH
from 10, 15, and 24 m depths. Amplification by RT-PCR
indicates that nitrogenase is being expressed in the anoxic water column.
detected in the anaerobic portion of the Mono Lake water column.
NifH
gene
expression has been detected in the anoxic water column (Fig. 4). However,
despite presence of diverse
nifH
genes and evidence supporting
nifH
expression
in the system, attempts to measure N
2
fixation with
15
N in the Mono Lake water
column have been unsuccessful [123]. N
2
fixation in this ecosystem is not likely
to be constrained by the availability of trace elements, since it occurs in algal
aggregates in the littoral region of the lake [92]. It is somewhat surprising that
N
2
fixation has not been detected in the water column, even though primary
production in this system is believed to be nitrogen limited [57]. However, there
