||Although I am in the School of Oceanography, my lab group studies river
chemistry and the processes between land and water that control bioactive
elements (carbon, nitrogen, phosphorous and oxygen). We have three primary
study areas: the Amazon Basin, Southeast Asia and the Puget Sound. My Master's
project specifically looked at the natural production of methane in the
flooded forests of the Amazon Basin. During the rainy season, the rivers
in the Amazon Basin flood into the surrounding forest creating an anoxic
environment for biodegradation. Microbes that normally decompose the material
on the forest floor to carbon dioxide cannot function without oxygen. When
standing water in the forest is depleted of oxygen, different microbes
will decompose the leaves using a metabolic pathway that ends with the
production of methane gas. Since methane is a greenhouse gas, scientists
are very interested in knowing how humans are changing the natural sources
and sinks of methane. My study site was located in the Brazilian state
of Rondonia, and contained areas of flooded primary forest as well as flooded
pasture. The purpose of my research was to quantify the natural emission
of methane in the untouched forest and compare it to the emission observed
in the flooded pasture.
Because my work is in the middle of the South American Continent, you
could say that I am a " terrestrial oceanographer". I applied to work aboard
the Polar Star as an opportunity to obtain some true oceanographic experience.
I was hired to work as part of the CTD crew, but I also plan on conducting
an additional experiment in denitrification. Nitrogen can be a limiting
nutrient for phytoplankton. This means if not enough nitrogen is present
in the water, or if it is in the wrong form, phytoplankton cannot grow.
Phytoplankton growth in turn affects how much carbon gets taken out of
the atmosphere and put into the ocean. This movement of carbon to the ocean
is important for understanding climate change. One way that nitrogen can
be taken out of the water is by sediment microbes that convert useful forms
like nitrate (NO3 2-) and nitrite (NO2 -) to molecular nitrogen (N2) or
nitrous oxide (N2O). Both N2 and N2O are gaseous forms of nitrogen and
eventually will diffuse out of the water column and into the atmosphere.
We expect there to be significant denitrification in the waters of this
cruise because of their interaction with sediments on the shallow, extensive
Arctic continental shelves.