4 August 2013 Where do you search for trace metals?...water, plankton, mud, and organisms

Journal

Researchers collecting water from the CTD (Conductivity, Temperature, and Depth).

Bob and Erlenmeyer flask — CTD seawater is filtered through specialized filters, one type for trace metals and suspended solids, and a different one for particulate organic carbon

Dr. John Trefry (Florida Institute of Technology) and his group are studying trace metals in the Chukchi Sea. This sea has many trace metals including arsenic (As), cadmium (Cd), mercury (Hg), and methyl mercury (MeHg), yet the concentrations are low and ephemeral. The levels noted in the Chukchi are all natural and not anthropogenic (caused by man). In a recent study, an old drilling site was located in an area with significantly higher trace metal content left behind from a deposit of drilling mud. Other than that one location, the sediments around Hanna Shoal are pristine. Another favorable factor in the health of Chukchi Sea is that the water is naturally flushed out every 6 months. If there is an area with high biomass and/ or a water column high in chlorophyll content, there will be low levels of Hg. Hanna Shoal has both high biomass and chlorophyll; it truly is a biological hot spot of productivity.

Yuchao and mud — Yuchao sampling the mud for oxygen, pH, and redox potential

An interesting thing about sediment composition is that if the sediment is high in sand then Hg concentrations are low. Sand has less surface area and a low charge and therefore, does not attract Hg. The opposite is true for clay.

Elemental mercury can be removed from an organisms system. Mercury becomes a problem when it bonds with another group, such as a methyl group. When this happens and it is in the protein of a life form, it can cause damage to the nervous system.

Austin and a plankton net — Austin is geared up to take a plankton sample using a hand net.

I learned a new word, biomagnification. It refers to the increased amount of some chemical (element or compound) as it goes up the trophic level. A trophic level is the place or position an organism is within a food chain. If plankton have 0.1 mg of a substance in their tissues, the creature that eats them like clams may now have 0.5 mg in its own tissue. Methyl mercury is a substance that biomagnifies. Now I have heard of bioaccumulation and that deals with the increase of a chemical within an individual organism. For example, some medications can bioaccumulate.