August 19, 2005
I can't believe it has been a week already! Time really went so quickly and yet I feel like I have always been on the Albatross IV. It's strange.
Now that I have helped Nora with the bottom grab a number of times, I feel like I know it well enough to explain it. I think I mentioned earlier that Nora is an intern scientist with the EPA. She and Don (who incidentally is also a Southampton College Alum) are doing a sediment study to test for toxics in the sediments that are from run-off of farms, factories, golf courses, etc. They are part of an on-going inshore study that stretches from VA to ME. This is the first time the study has been brought offshore.
First, water samples of bottom, mid, and surface waters are taken using nisken bottles. One nisken bottle is attached to the CTD line and sent down. When the line is half way through the depth of the water column, a second nisken bottle is attached. When the bottles are about 5m from the bottom, a messenger weight is sent down the line to trigger the bottles to close, trapping in the water sample. As I briefly mentioned earlier, 1000mLs of water from each of the 3 samples is filtered. The filtering is done so that the water can be tested for three things, nutrients, total suspended solids (TSS) and chlorophyll. The filtering process takes awhile because there is only enough equipment for us to filter 2 of the 3 samples of water at a time, and only 200mLs at a time. Generally we filter surface and mid first and then go back and filter the bottom. After the second filtering of each "level" of water, a water sample is taken from the filtered "nutrients" water. This will be sent to another scientist at the EPA for further nutrient analysis. The nutrient filters are the easiest to deal with. After the water is filtered, the filters are simply wrapped in aluminum foil and bar-coded (the matching barcode goes on the data sheet). The TSS filters come pre-weighed so they have special tins they need to be wrapped in before they can be wrapped in aluminum foil and bar-coded. Also, the TSS filters need to be rinsed with deionized water during the last few seconds of filtering. This is to make sure all of the sediments are on the filter disc and not on the side of the filter. The chlorophyll filter discs are rinsed with MgCO3 (Magnesium Carbonate) during the last few seconds of filtering. This helps reduce the possibility of degradation of the sample. These filters are also wrapped in aluminum foil and bar-coded. The filters all need to be handled with forceps (science tweezers). Touching them isn't allowed, which can at times be a bit tricky. Did you ever try to fold a tiny filter disc (about the size of a nickel) in half, using only a pair of forceps, while aboard a rocking boat? All of the filters and water samples are stored in the freezer to preserve them until we return to shore.
Two things happen to the sediment that is obtained in the bottom grab. The sample from one of the grabs is sieved out for organisms. Depending on the sediment, this can be a fast process or take a few hours. Mud is pretty quick and easy, sand takes forever. Ideally we want one 1L bottle of organisms (on one of the sand grabs we ended up with six bottles). The sediment is sieved down as much as possible using a light spray from a hose. The remaining organisms (and sometimes sediment) are bottled. Before the bottle is capped, taped (to ensure the seal), and labeled, 100mL of Rose Bengal formalin and more ocean water is added. The formalin preserves the "critters" and the Rose Bengal dyes their body tissues so that they stand out from the sediment. The water fills up the bottle, removing possibility of organisms sticking to the bottle or cap.
The other sediment sample from the bottom grab is bottled and used for toxicity testing. Only the top layer of the grab sediment sample is used. There are 5 bottles that sediment is put in- one is to test for metals, one is to test for organics, one is to test grain size, one is to test total organic carbon, and one tests toxicity. All of these bottles are taped closed and labeled. They are stored in the freezer (which helps with preservation) until we get back to shore.
Everything that is bottled or wrapped gets a barcode sticker that has a matching barcode sticker that goes on the data sheets. I kind of like that idea- it saves time from hand labeling everything.
Clean-up takes a bit of time as well. Everything (spoons, the grab, the buckets from under the grab, the pot that the sediment sample was transported in) needs to be scrubbed using soap and water. The deck needs to get hosed down. All of the filters used for filtering water need to be rinsed using deionized water and new filters need to be put on. It really is a good thing that bottom grabs only happen every fifth station because it takes a few hours to completely process each bottom grab.
2:50 P.M. (same day)- Today has been another gorgeous day at sea! Early this morning was a comedy of errors (bound to happen in the wee hours of the morning). First, part of one of the nisken bottles that the EPA uses broke off and fell in the ocean while it was being used to take a sample. It had to be replaced with their only spare. Then, two bottom grabs were attempted but the bottom was really rocky so we came up completely empty both times. We had to call off the bottom grab. Then, on our final plankton tow of our watch, the CTD started "acting funny" (to quote Joe). We ended up having to wake Jerry and one of the engineers. They discovered that there was a bad connection so one of the wires had to be spliced and the CTD had to be rewired. It seems to be fine now. Thankfully the rest of today has been pretty uneventful.