SELECT Sources.Source_ID, Sources.Serial_Number, Sources.Date_Of_Receipt, Sources.Form, Sources.Nuclide, Sources.Activity, Assets.Asset_Description, Sources.Reference_Date, Sources.Estimated_Activity_On_Receipt, Sources.Active_Dimensions, Sources.Overall_Dimensions, Sources.Description, Sources.Last_Test_Date, Sources.Test_Validity_Months, Sources.Risk_Assessment, Sources.Current_Location, Sources.Disposal_Date, Sources.How_Disposed, [COLOR="Red"]Sum(Sources.Activity) as TotalActivity[/COLOR]
FROM Sources INNER JOIN Assets ON Sources.Serial_Number = Assets.Asset_Serial_Number
GROUP BY Sources.Source_ID, Sources.Serial_Number, Sources.Date_Of_Receipt, Sources.Form, Sources.Nuclide, Sources.Activity, Assets.Asset_Description, Sources.Reference_Date, Sources.Estimated_Activity_On_Receipt, Sources.Active_Dimensions, Sources.Overall_Dimensions, Sources.Description, Sources.Last_Test_Date, Sources.Test_Validity_Months, Sources.Risk_Assessment, Sources.Current_Location, Sources.Disposal_Date, Sources.How_Disposed;