How do sediment traps work?
The basic sediment trap consists of a broad funnel with a collecting jar at the bottom. The funnel opening covers a standard area (such as 0.25 square meter [2.7 square feet]) and has baffles at the top to keep out very large objects that might clog the funnel. The trap clamps at a specific depth to a fixed cable attached to an anchor or buoy. Traps are often placed very deep, where they can catch sediment near the ocean bottom. When a ship returns to retrieve the trap, the crew activates a remote-controlled device called an acoustic release. The release severs the line between the trap and its anchor, and the trap floats to the surface with its samples. The first sediment trap was deployed in 1978 off Bermuda, in more than 3,200 meters (2 miles) of water. In more recent experiments, several traps have been spaced every 500 meters from the upper ocean to 500 meters above the seafloor. By comparing the trap catches, scientists learn how much material gets recycled by sea life on its jou
