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A digestion method for trace metals recovery from oil and grease contaminated soils
Author(s) -
Cook Nicola,
Turmel Marie-Claude,
Hendershot William H.
Publication year - 2000
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2000.642609x
Subject(s) - grease , soil water , chemistry , digestion (alchemy) , environmental chemistry , detection limit , soil test , contamination , inductively coupled plasma , atomic absorption spectroscopy , inductively coupled plasma atomic emission spectroscopy , soil contamination , chromatography , environmental science , soil science , ecology , biochemistry , physics , plasma , quantum mechanics , biology
Oil and grease contaminated soils are difficult to digest using the common HNO 3 –H 2 O 2 digestion method. Even after an overnight pre‐digestion with HNO 3 and subsequent heating, the addition of H 2 O 2 caused violent reactions in soils with oil and grease, resulting in the loss of the samples. At low metal concentrations at least a gram of soil needs to be digested to obtain concentrations measureable by flame atomic absorption spectrometry (FAAS) or inductively coupled plasma–atomic emission spectrometry (ICP‐AES). We developed a modified procedure using HNO 3 –HClO 4 for the analysis of total trace metals that can be used on all types of soils including those with oil and grease. Recovery rates of 99, 94, 114, 92, and 83% for Cd, Cu, Ni, Pb and Zn, respectively, were obtained for standard reference material (SRM) NIST 2710 (Montana Soil). Soils with ≈1000 mg kg −1 oil and grease were successfully digested and gave extract concentrations suitable for analysis on FAAS or ICP‐AES. Compared to the common HNO 3 –H 2 O 2 soil digestion method, the proposed method was as effective (no significant difference) in extracting Cu, Pb, and Zn and was significantly better in liberating Ni from the soil. With the HNO 3 –H 2 O 2 soil digestion method the Cd concentrations were often below the limit of detection by FAAS but were measureable in the HNO 3 –HClO 4 digests. Variability of results using the proposed method was reduced in some cases.