Cleanroom for the ends of the Earth

Global warming is a hot topic at present and some of the work being undertaken to try to combat this threat is taking an unusual direction. The Chemical Oceanography Department at the Leibniz Institut für Meereswissenschaften (ifM-Geomar) in Kiel, Germany, is researching the role of trace metals on primary productivity in the ocean. This is linked to the ability of algae in the ocean to convert carbon dioxide into oxygen. The huge tracts of sea in the Southern Oceans offer the possibility of harnessing the power of the ocean borne microbes to combat the growth in carbon dioxide and thus global warming. Unfortunately certain trace elements, such as iron, are lacking and these are necessary for microbial activity. IFM is taking part in EIFEX (European Iron Fertilisation Experiment), a mesoscale experiment in which algae growth in the iron-limited Southern Ocean is promoted by adding iron oxide (ferrous sulphate) to a 50km2 study site. This approach has been suggested as a possible method to remove anthropogenic CO2 from the atmosphere and thus mitigate the effects of global warming. In order to measure the effects of adding small amount of iron oxide to the sea, it is necessary to perform very careful measurements of iron concentration in seawater samples. This has to be done in a clean, trace-element-free atmosphere; a special cleanroom is needed, with no visible metal in the room or in the air stream. The cleanroom has to be housed in a container, built to offshore module standards, to be capable of performing on board a research ship in the severe weather conditions found in the Southern Oceans.

Picked for the job Clean Modules, which specialises in the design, construction and project management of cleanroom installations, controlled environments, clean air and conditioning systems, was selected to build the cleanroom. The company also has considerable expertise in pharmaceutical, medical, hospital, and biotechnology applications. The container cleanroom was specially designed to fit into the footprint of a standard "20 foot" container. It provides an ISO Class 7 environment for two technicians with an ISO Class 5 laminar flow workbench and other work areas. The module is entered via a Class 7 clean change room. A very compact plant room houses the air system and associated systems. Externally, the module comprises a steel container built to meet EN 12079 and American Bureau of Shipping offshore accommodation module standards. Internally, careful consideration was given to every aspect of design and construction. The cleanroom houses an ISO Class 5 laminar flow workbench, which is provided with a non-metallic work surface and "fiddles" with anchor points to secure the experimental equipment. Additional worksurfaces are provided, again with fiddles and equipment securing points. A special sea water sampling system is provided to bring samples into the cleanroom from a sampling pipe immersed in the sea next to the research ship. Only plastic has been used throughout the construction of the cleanroom. Plastic is also used for much of the air system, including the HEPA filter and housing. The plant room is extremely compact. In addition to the air filtration system a temperature control system is provided, as the module has to operate from Antarctic sub-zero conditions through to tropical heat. Power is provided from the ship's supplies and is split between 'dirty' and 'clean' supplies. A services hook-up point is provided, which also incorporates telephone and data connections, cold water and seawater sampling connection. An uninterruptible power supply is provided to ensure sensitive data collection and computing equipment can run without disruptions from variations in supply. The container cleanroom went on its first mission in early 2004 on the research ship Polarstern and, according to Dr Peter Croot, it "proved to be excellent at maintaining cleanroom conditions despite the environment encountered outside". "During storms waves broke over the cleanroom and a neighbouring container was even stoved in 40-50cm after a direct hit. The door of the cleanroom didn't leak and this is a remarkable achievement in itself for the Southern Ocean. During the cruise we were able to collect and analyse open ocean samples with apparently little or no contamination, as demonstrated by low background iron concentrations of 10-100 pM (1012 mol L-1)," he added. The container is scheduled to return to the Southern Oceans next year as the research group continues its work "at the ends of the earth".