In this part of the Pacific, some of the iron has been traced to desert sand blown across the miles from Asian deserts. Using minute amounts of radioactive C14 as a marker, he can check for how much carbon is incorporated by the tiny plankton and calculate from that the rate of plankton biomass produced. Remember, plants need light and sunlight only penetrates the surface water and down the column for 100m. This is known as the euphotic zone. Dr. Strutton works closely with the ship's survey technician, Dennis Sweeney, in setting the collecting bottle depths for the CTD array.
Sunlight is the trigger for photosynthesis to occur.
Knowing how much radiation from the sun and which wavelengths are penetrating the sea surface is discovered from the other instrumentation Peter brought onboard. With his long hair tied back out of the wind, he attaches sensors to the bridle areas of several buoys being prepared for deployment along our transit. The bridle is a metal, inverted tripod cage bolted onto and weighted below the toroid of the buoy. The sensor will measure light emissions reflecting upward from 2m below the surface in the 400-700nm range, or in other words, the visible spectrum of red through blue light wavelengths. When color graphs are plotted from his data so far, you can see the interaction of marine temperature, phytoplankton activity, and the changes that have occurred due to El Nino.