Day 28 Monday October 24, 2011 01:37 GMT

Things are going smoothly.  The winch is working beautifully, the seas are calmer and the countdown until dry land is at 1 week now.  We have just moved through another time zone, we are now at 2 hours ahead of EST and currently on Brasil time.

There have been more whale sightings recently, especially as we moved to the western side of the Rio Grande Rise (located right around 35 deg W).  This rise is similar to the Walvis Ridge, that we passed early on into the cruise, in that it is an aseismic ridge.  An aseismic ridge is a long, linear, mountain chain that is formed by volcanic activity.  An interesting factoid of these ridges is that earthquakes do not occur in these regions.

Continuing with the discussion of the scientific groups sampling we come now to DIC and DOC.

DIC (dissolved inorganic carbon) references the total sum of inorganic carbons such as CO2, carbonic acid, bicarbonate anion, and carbonates.  DIC is linked to the measurements being done to determine the ocean acidification rate.  Ocean Acidification, caused by the absorption of DICs from the atmosphere, contributes to the breakdown of calcium carbonates, a necessary building block for organisms such as coral and shellfish.  For more information on Ocean Acidification see NOAA's site:
http://www.pmel.noaa.gov/co2/story/What+is+Ocean+Acidification%3F
Measurements taken in the ocean are a good way to measure the amount of DIC that is in the atmosphere.  It is hypothesized that one quarter of the DIC in the atmosphere is absorbed by the oceans.

DOC (dissolved organic carbon) is generally derived from the decomposition of organic materials, i.e., plants and animals.  DOC plays an important role in the carbon cycle found in oceans through something called the microbial loop.  This loop is simply a cyclical food chain where DOC is incorporated into a bacterial biomass and then carried through the chain until it returns eventually as DOC.
There is an indication that when high concentrations are found in areas that are typically low in DOC amounts, such as the deep oceans, it is caused by human influence.


Thanks for reading.
-Elizabeth

Our current position is on Station 94 at:
30 0.02 S    and   38 01.00 W


Below are several photos of: a) Location of Rio Grande Rise (located around the 35 W line) and b) Driving along the coast in Cape Town