We wrapped up our final day of water sampling with a round of CTD casts in the vicinity of the Deepwater Horizon site. In all, we completed 62 casts. This made for a very hectic week, but we did it! We’ve accomplished a lot in a very short time.
Some of us managed to sneak in enough downtime to make “shrunken cups.” Anybody who has ever been on an at-sea research expedition involving CTDs has probably made at least one. You take a plain styrofoam cup and draw your favorite design on it in permanent marker. Then, you put it in a mesh laundry bag and tie the bag to the CTD rosette frame. When the CTD is lowered, the cups go down with it.
Because the pressure at the depths of the CTD casts is much greater than at the surface -in fact, each 33 feet of sea water exerts the same amount of pressure as the ENTIRE atmosphere – the air is squeezed out of the air pockets in the styrofoam, compressing the cup do about a quarter of its original size. Check out the “before” and “after” photos. (In case you are wondering: Yes, we have tried this with styrofoam wig heads, with equally impressive results. Just not on this trip.)
Interestingly, our research seems to indicate that the same pressure that causes the cups to shrink has also played a role in the fate of the natural gas that was emitted with the oil from the Macondo well. While natural gas is lighter than water and might be expected to rise to the surface, it seems that the enormous pressure of the 5000 feet of water above the well exerts enough force to cause much of the natural gas to dissolve into the deep ocean instead.
It’s been a great nine days, but it’s time to head for land. Back to Pascagoula tomorrow!