March 13, 2001 to June 2, 2001
Monterey to Hawaii and back
May 28, 2001: Leg 5; Day 7
Log Entry: Hello and Happy Memorial Day. Where did you go for Holiday? We toured the middle of the Pacific. We’re at 30o 37’N, 137o 10’W, a little past half way to home. The ship is running along at 9 knots under a slight overcast and a 15 knot wind that is backing around to the North as we pass along a high pressure front. Gale warnings for the coastal region are predicted at about the time we’ll arrive, as several fronts pile up, but things are very nice right now, right here.
The crew is preparing a barbeque dinner for the holiday. Doug has posted a menu of:
Split Pea Soup
New York Steak
Hawaiian Lobster (which he says is from Nicaragua)
Corn on the Cob
H’mmm, sounds good. One of the things I enjoy about going to sea is a bowl of homemade soup for lunch. Doug has been excelling at that.
While being at sea on a holiday is usually not too much fun, I’m enjoying this one. All of our data is coming together and a really neat story is emerging. First, a little background. Deep water concentrations of iron are about 0.6 nM, a little higher near the coast (nM = nanomoles/liter; nano = 10^-9 and a mole is the number of atoms in 1 gram of carbon 12 = 6.023x10^23). In more familiar terms, 0.6 nM is 30 parts per million of a part per million (30 parts per trillion). Iron concentrations are usually much lower in surface waters. The global average about 0.05 nM, or 2 parts per trillion (2 kg of iron in a cubic kilometer of seawater). Phytoplankton consume the iron for their growth, which drives the concentrations to such low values.
On our way out to Hawaii in March, before the high dust input season, the values of iron that we saw were typical of the global surface water average – 0.05 to 0.15 nM. Now, after massive storms of Asian dust have passed through the area, iron concentrations have jumped to nearly 0.7 nM near Hawaii. As we’ve traveled east, away from Asia, iron concentrations (and aluminum) have dropped steadily until they reached background around 145oW. The enriched surface iron concentrations extend down to 100 m in our vertical profiles. And chlorophyll concentrations have doubled. Very neat.
All this excitement has turned Josh into a philosopher and he has penned the Ode to Iron:
On a ship in the ocean
Sat a young chemist in motion
O’ what a wonderful chemical potion
Many questions he did ask
of that iron in the flask
While tending to his daily task
Never enough to see
This rust is the key
For the all of the plants that are to be
From the east it must sail
While spring winds prevail
Til it drops from the cloud like a veil
To the ocean it must settle
Leaching away its precious metal
Becoming fish soup in a kettle
And this it might seem
Turns the blue ocean green
And makes a fisherman’s dream
We will leave you to ponder that for now. IT’S DINNER TIME!
Aloha, MBARI Sensors Group