Searching for the plumes

This time of year, the Gulf of Mexico experiences frequent and sometimes severe storms.  Over the past few days, the wind has been blowing 20 knots steadily, with gusts up to 30 knots.  The seas are up and we’ve been bounced around a lot.

From Gulfport, we headed to “ground zero”, where the City of Ships remains, as the relief well operation continues.   We reoccupied one of the stations from the Walton Smith cruise and saw no signals at depth.  This was no surprise – we did not expect to see signals so close to the wellhead since the well has been capped for ~6 weeks.

We moved to the south and east to obtain samples from a “control” area that should not have had deepwater features (e.g. plumes) like those we observed to the S/SW of the wellhead in May and June.  As expected, we saw no features at depth at this station. Next, we moved west, using model predictions of 1200m deep ocean currents to guide our search.  We're mapping and have not found the core of the plume – we want to find the now ~100 day old plume that we studied in May and June.  So far, we're seeing very weak CDOM signals that are at depths consistent with those where we observed plumes 3 months ago.  Finding the plume core will be a slow, methodical process, but I think we are moving in the right direction.

In addition to water sampling, we are collecting sediment samples using a “multi-corer”.   This instrument is a monster –large and a bit unwieldy – but it’s been behaving and we’ve gotten great samples at three stations.  Out here the water depth is >2000m and the surface of the sediment is a combination of calcareous (pteropod and foraminfera) ooze and fine-grained mud.  We have not seen oil on the sediment surface but all of our coring stations so far were not beneath extensive surface oil or deepwater plumes. We plan to go back closer in to ground zero and collect sediment samples there during the second leg of the cruise. The one good thing about bad weather is that a break in the weather often generates a spectacular rainbow (in this case a double rainbow).

For now, the search for the aged plume core continues.