Surface contamination, shipping

To fulfil the background requirements typical of rare event physics, particular care was dedicated to the selection and treatment of the materials used for the construction of CUORICINO the crystals where grown with low contamination materials in China and sent by ship to Italy where they have been optically polished with specially selected low-contamination powders. The mechanical structure of the array was made exclusively in OFHC copper and PTFE both these materials have an extremely low radioactive content. All the copper and PTFE parts of the mounting structure underwent a chemical treatment to remove any possible surface contamination. Finally, the array was assembled in an underground clean room in a N2 atmosphere to avoid Radon contamination. 

Step 9. Promptly place the emptied shipping container into a plastic bag and seal bag. Place bag into a plastic counting container and cap the counting container. Swipe counting container to check for surface contamination. If clean, seal counting container in plastic bag and place on Ge detector. 

Air flotation is simply the production of microscopic air bubbles, which enhance the natural tendency of some materials to float by carrying wastewater contaminants to the surface of the tank for removal by mechanical skimming. Many commercially available units are packaged rectangular steel tank flotation systems shipped completely assembled and ready for simple piping and wiring on site. 

Although the corrosivity may not be high provided the condensed moisture remains uncontaminated, this rarely happens in practice, and in marine environments sea salts are naturally present not only from direct spray but also as wind-borne particles. Moreover, many marine environments are also contaminated by industrial pollution owing to the proximity of factories, port installations, refineries, power stations and densely populated areas, and in the case of ships or offshore installation superstructures by the discharge from funnels, exhausts or flares. In these circumstances any moisture will also contain S, C and N compounds. In addition, solid pollutants such as soot and dust are likely to be deposited and these can cause increased attack either directly because of their corrosive nature, or by forming a layer on the surface of the metal which can absorb and retain moisture. The hygroscopic nature of the various dissolved salts and solid pollutants can also prolong the time that the surface remains moist. 

One alternative method for preparing field fortifications solutions/suspensions is to prepare each fortification sample of each matrix in a separate mini-vial in the analytical laboratory and ship the vials to the field for use. This procedure precludes the use of pipets in the field and may be useful when Field Scientists not experienced in the use of pipets are involved in the field fortification process. One disadvantage of this procedure is that the mini-vials, if not designed correctly, will be hard to handle in the field, and surface tension of the suspension or fortification solution will tend to leave unacceptable amounts of the solution/suspension in the vial or at the lip of the vial and not on the matrix in question. This procedure may lead to cross-contamination of samples as the field fortification liquid is forced from the top... 

Surface-water samples are usually collected manually in precleaned polyethylene bottles (from a rubber or plastic boat) from the sea, lakes, and rivers. Sample collection is performed in the front of the bow of boats, against the wind. In the sea, or in larger inland lakes, sufficient distance (about 500 m) in an appropriate wind direction has to be kept between the boat and the research vessel to avoid contamination. The collection of surface water samples from the vessel itself is impossible, considering the heavy metal contamination plume surrounding each ship. Surface water samples are usually taken at 0.3-1 m depth, in order to be representive and to avoid interference by the air/water interfacial layer in which organics and consequently bound heavy metals accumulate. Usually, sample volumes between 0.5 and 21 are collected. Substantially larger volumes could not be handled in a sufficiently contamination-free manner in subsequent sample pretreatment steps. 

---