My name is Dan Razionale, and I am currently a Marine Science Undergraduate on the Geophysics track at Eckerd College. My research focuses on various Geochemistry following the Deep Water Horizon Blowout event of 2010. I use sediment cores collected from the C-IMAGE cruises to make integrated graphs and tables illustrating how Reduction and Oxidation (Redox) environments are responding to the blowout event. By separating these cores into very small increments (2-5mm) from the top down, and analyzing them separately, I am able to create comprehensive depth profiles of specific metals in the surficial sediments.
These metals are named ‘trace metals’ and are excellent indicators of Redox boundaries, or areas where the sediment switches from being oxidizing to reducing; the best ones to look for as indicators are Manganese, Rhenium, Cadmium and Uranium. My main findings have been that, following the oil spill, a peak in Manganese Oxide (MnO2 ) that denotes the Redox. boundary has significantly rose, indicating a depletion of oxidizing environments and an enhancement of the reducing environment. In other words, this indicates a decrease in the amount of oxygen in the surficial sediments which, in turn, allows fewer organisms to live here.
While I have been collecting cores to continue this research back at Eckerd, my roles on this year’s cruise entail more than simply retrieving the core as is it comes off the sediment multi-corer from the bottom of the ocean. For this cruise, I have deployed a specially made core at various sites to sample the pore water of surficial sediments; this core has tiny holes drilled in 1 cm increments from top to bottom. By inserting filter probes into these holes and attaching them to syringes, I am able to gather the water trapped in pore spaces in the sediment. Similarly to my other research, I use these to create depth profiles of trace metals found in these pore waters; however, at specific sites of interest, I split the volume of pore water gather and use half to test for nutrients.
Today marks the end of coring operations on the Weatherbird and, after the last station at 6:00 AM this morning, I caught up on some much needed sleep. For coring ops, the geo. crew must be ready to go as soon as we arrive at each predetermined location. Since these sites are mostly separated by only a couple hours, we essentially are working around the clock, with only a few hours in between to sleep.
Friday morning, at our last location, I retrieved my specialized core from the multicore, a process which in total can take up to 90 minutes based on depth. I then began immediately inserting probes and syringes to gather the pore water; once this is done, I headed in to the lab.
In order to analyze both trace metals and nutrients, I need a total of 2 milliliters, 1 mL for each analysis. After some tedious pipetting, I had 1 mL in all 32 test tubes (16 total probes and syringes). The nutrient tubes then go immediately into the freezer, to prevent unwanted oxygen penetration and to prevent anything from precipitating, whereas, the trace metal samples are slightly acidified and then packaged, to be processed back at Eckerd labs. This whole process takes about an hour to 90 minutes to complete.
This is my first research cruise, with the C-IMAGE Consortium and overall, and it has been a surely unforgettable experience. As an undergraduate, rarely do I get the opportunity to participate in science of this caliber, and I have been taking full advantage of the wisdom and experience that my colleagues have to offer. While I have learned a lot, it has also been a pleasure getting to know and hang out with the science crew for the past 10 days; it’s pretty interesting getting to know someone when you’re covered in mud together at midnight, and covered in fish blood together at midday.