There is reasonable information on heavy metals at a national level from the National Soil Inventory but little or no information on organic contaminants.
Mae gwybodaeth resymol am fetelau trymion ar lefel genedlaethol ar gael o’r Rhestr Briddoedd Cenedlaethol (National Soil Inventory) ond does dim, neu fawr ddim gwybodaeth am halogion organig.