Yeah, that's actually a lot more difficult than you make it sound. See, for instance, http://en.wikipedia.org/wiki/Vienna_Standard_Mean_Ocean_Water http://en.w

Yeah, that's actually a lot more difficult than you make it sound. See, for instance, http://en.wikipedia.org/wiki/Vienna_Standard_Mean_Ocean_Water http://en.wikipedia.org/wiki/Vienna_Standard_Mean_Ocean_Wate....