"I'm not in any way saying [the microbes are] a magic cure," Terry Hazen, a microbial ecologist at Lawrence Berkeley National Laboratory, said in an interview Thursday. "There were oil degrading bugs, but I expected them to be there."
However, "nobody in their right minds" would say you could put that much oil in the water without an adverse effect, Hazen said. Over four million barrels poured into the Gulf from April 20 to July 15. "We just don't know what ultimate effect it will have on the environment," he said.
The Berkeley Lab team studied the same large plume of oil near the wellhead as did researchers from Woods Hole Oceanographic Institution. The Woods Hole team reported that the oil persisted for several months without substantial degradation. Those researchers took their "forensic snapshot" in
late June and have not been back since.
The Berkeley Lab team has been "out there continuously and we're still out collecting samples," Hazen said. "As of three weeks ago, we haven't been able to detect a deepwater plume around the well. But we have the bacteria which are still elevated where the plume was."
Examining samples from the plume in the laboratory, "we found multiple lines of evidence that biodegradation was going on," Hazen said.
He said the cold water-loving bugs didn't spring up spontaneously. They probably had their origin "chomping on naturally occurring seeps, but had never been described before," he added.
The Berkeley Lab report on the degraded plume should not be taken as contradicting the Woods Hole finding that the plume was not degrading, Hazen said.
The Wood Hole team was not measuring specific biological parameters and microbiology, Hazen said, but was "measuring the oil in some detail and some of the chemistry."
The oil was dispersed into very small droplets of 10 to 60 microns, diluted to concentration no higher than 10 parts/million, and invisible to the naked eye, Hazen said. The combination of highly dispersed, small droplets of relatively volatile crude made it very biodegradable, Hazen said.
Hazen focused on one form of hydrocarbons--alkanes--that were being rapidly degraded by about half every four days.
Critics have pointed out that the Macondo oil contains thousands of types of hydrocarbons which have a half life much longer than the alkanes.
Hazen agreed that some other compounds in the oil "will be quite recalcitrant" and resistant to degradation, but "looking at this particular oil, 80% is alkanes and we focused on the largest component. That seemed like a logical place to look for rates of biodegradation."
Despite reports that other researchers are still monitoring plumes, Hazen said he doubts there are remaining plumes related to the Macondo well. He said his team didn't find any additional plumes in proximity to the wellhead, and "I would question whether you would find another plume that's a long distance from the wellhead. I would question whether it's a plume from a natural seep."
China Chemical Weekly: http://news.chemnet.com/en/detail-1403616.html
