Trace Metal Clean Sampling CTD

The Conductivity-Temperature-Depth (CTD) system uses the SBE 911plus model manufactured by Sea-Bird Electronics, Inc. (SBE). It consists of the 9plus main unit (including a pressure sensor) and the SBE 11plus Deck Unit. For the trace element clean sampling system, the CTD is housed in a titanium alloy casing to prevent metal interference. This model is equipped on research vessels and features eight A/D channels, capable of collecting vertical profiles of pressure (depth), temperature, and conductivity up to 6000 meters. These measurements can be converted to salinity, density, sound speed, and other basic hydrographic data. The system is also equipped with oxygen, transmissivity, and fluorescence sensors to obtain biochemical parameter profiles.

The trace element clean sampling system uses a titanium alloy SBE 32 rosette sampler powered and controlled by the CTD, allowing water bottles to be closed at different depths to collect seawater samples. The sampler is equipped with electromagnetic valves controlled by the Deck Unit, which activate the valves to seal the bottles.

The water sampling bottles are Ocean Test Equipment, Inc. (OTE) model 115ES external spring-type 12L bottles, internally coated with Teflon. All external metal parts are made of stainless steel or titanium alloy backplates to avoid contamination.