Departure

The tugboat Montevideo gently pulled us out of our berth at the port of Montevideo, Uruguay, today. It is a busy port with massive cranes loading cargo ships and the smell of manure filling the air as live cattle are loaded onto ships.

Tugboat pushing R/V Knorr out of its berth and toward the
South Atlantic (Winnifred Johnson, WHOI)

This port is the entry and exit for goods going to and from Uruguay, Paraguay, parts of Brazil, and Argentina. As we wait for our turn to leave the port ,a tugboat pulls a cargo ship, many times the size of the Knorr out of its berthing place. The port is located in the mouth of the Rio de la Plata and the water is full of mud and silt. On the horizon there is a barely visible streak of blue that shows where the river and the ocean meet.

We will be working on the R/V Knorr  for the next 45 days. Our most southerly samples will come from a latitude of 38S. We will then travel north along the western Atlantic, crossing the equator and disembarking in Bridgetown, Barbados (13.2N). This journey will take us from temperate latitudes through the tropics, sampling more nutrient-rich water in the south and entering low-nutrient water as we move north, while also crossing the Amazon River plume. There will be a variety of sampling to look at microbial life and chemistry of this part of the Atlantic Ocean. We will also be sampling for everything from viruses to phytoplankton and chemical analyses ranging from broad snapshots of the small organic molecules present to identify of individual lipids.

A cattleship loading as Knorr leaves the Port of Montevideo
(Winnifred Johnson, WHOI)

The cruise track is being dictated by the presence of north Atlantic deep water. This is water that is cold and salty, which makes it dense and causes it to sink down to around 3000-4000 meters in the North Atlantic near Greenland. This body of water then travels down the western Atlantic, transporting any matter that is associated with it. This is part of a deep ocean transport system that results in carbon and nutrients eventually being moved all the way into the North Pacific.

Radiocarbon dating shows us that some of this material is thousands of years old. Part of the goal of this cruise is to understand how the organic matter that is being transported along this route changes and the processes that are transforming it.

Over the coming weeks we’ll be uploading videos and blog posts highlighting all of the diverse work occurring on this cruise.