Well they are all in the same table. There are four fields:
Latitude, Longitude, Type of chemical, Emission(kg)
The lat and long are in wgs (but I transfer them to ED50).
I plotted these points in ArcMap and this was ok. But then when I tried to use kriging, it said 'unable to estimate the semi-variogram'. I have no idea what this means. Maybe there is something I am doing wrong.