The IAEA-405 estuarine sediment was collected from the intertidal mudflats of the Tagus estuary (Portugal)As. 23.6 mg/kgHg .0.81 mg/kgPb. 74.8 mg/kgCd . 0.73 mg/kgHg, methyl-.0.00549 mg/kgSb. 1.81 mg/kgCo . 13.7 mg/kgLi.72 mg/kgSe. 0.44 mg/kgCr . 84 mg/kg