Please excuse the lag in posting, I’ve been traveling and without internet for a few days! We reached port at Praia, Cape Verde at 9AM on Sunday December 11 successfully ending the cruise. The Knorr will steam directly back to Woods Hole, MA and is expected to arrive December 23, just in time for the holidays. All of our gear and science equipment was left onboard and we will meet at Woods Hole after Christmas to pack and ship home all of our belongings.
Overall the cruise was a success, we set out with an ambitious plan and only had to cut two small three hour stations due to the weather (there is only so much trace-metal sampling you can do in the middle of a tropical storm!). The wonderful group of scientist involved in this cruise had a huge part in its success. Going to sea is like being in grade school and attending your first overnight summer camp. It’s a collection of characters, of people that you normally would never have met but suddenly find yourselves living together, sleeping in bunk beds and relying on each other for moral support.
Over five weeks at sea, team mercury has analyzed 2000 samples (~500 samples, four species of mercury each) and will continue to analyze an additional 400 filters for particulate mercury back home in the lab. Though I don’t have an official count, thousands of samples were collected on this cruise and it will take years for everything to be processed and analyzed. I mentioned before that each sample collected has a special GEOTRACES ID number – this means that once all analyses are completed I will be able to compare my data for mercury with other nutrients and metals. This gives us a powerful advantage in understanding how mercury cycles and reacts throughout the Atlantic Ocean.
Once all of our data is finalized we will be able to see how mercury concentrations change horizontally (from east to west across the basin) and vertically (from the surface to the ocean floor). Along this vast cruise path the ocean changes a lot, and it will be interesting to see how these changes are affecting mercury. We hope to use data from this cruise to study the main sources of mercury to the ocean. Mercury can enter the ocean from both natural and anthropogenic (man-made) sources, however, in the open ocean we expect most is from human activities. Stronger scientific evidence of man-made mercury entering the ocean could influence policy makers to enforce more stringent pollution control regulations, especially in regards to coal emissions which are a major source of mercury to the atmosphere. We also hope to learn more about methylmercury, the species of mercury that is able to travel through marine food webs and into the fish that end up on our dinner plates. Understanding more about how and where this toxic species is produced will hopefully make steps towards protecting fish as a world-wide food staple. It’s crunch time for me now, I am scheduled to present our data from the cruise in February at the international Ocean Sciences meeting in Salt Lake city Utah!