Intercalibration in chemical oceanography-Getting the right number

Intercalibration has a strict metrological definition, but in brief, it's an open sharing of methods and results between laboratories to achieve the most accurate data with the fewest random and systematic errors. In the field of chemical oceanography where concentrations of many constituents can be in the nano- to picomolar range, the salt water matrix can be difficult to analyze, and knowing the exact concentrations, or even chemical forms, of biologically required elements is essential, intercalibration is a very relevant and needed tool. Implementing it is not simple because errors can occur at any step in the process of taking a water or particle sample, handling and processing it, and finally analyzing it and treating the resulting data. The international GEOTRACES program provides a good example of implementing intercalibration for studies of dissolved and particulate trace elements and isotopes, and is described here.