Hundreds of liters of filtered seawater are collected at each station to look at the distribution of dissolved metals and nutrients; but to understand the bigger picture we also have to examine the chemistry of particles suspended in the same water. Particles in the ocean are composed of dust that falls in from the atmosphere, sediments stirred up from the ocean floor and continental margins, and decomposing biological material. Metals and nutrients can grab on or break free from marine particles at various depths in the water column which can alter the distribution of dissolved elements. At each station specialized particle pumps are deployed by researchers from Woods Hole Oceanographic Institute. The pumps have to be manually attached to a wire a depth intervals (pictured above) and spend four hours pumping hundreds of liters of seawater through two different sized filters. The filters are brought into the main lab bubble for processing where HEPA filters and plastic sheets protect the samples from any dust contamination in the ship.
Dan is cutting the filters into sections that will be distributed to different labs. I will bring home a small piece of each filter to analyze for methylmercury and total mercury back at Wright State.
Sara is processing filters in a glove box to minimize exposure to oxygen which could chemically alter some of the elements she is interested in. Oxygen is pushed out of the glove box by pumping in nitrogen gas; entry occurs through the chamber on the right where samples sit and wait to equilibrate with air inside the glove box.