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Speciation of Chromium in Artificially Contaminated Soil Reference Material GSJ JSO‐2 Using XANES and Chemical Extraction Methods
Author(s) -
Tsuno Hiroshi,
Ohta Atsuyuki,
Kagi Hiroyuki,
Imai Noboru,
Tao Hiroaki,
Nomura Masaharu
Publication year - 2006
Publication title -
geostandards and geoanalytical research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.037
H-Index - 73
eISSN - 1751-908X
pISSN - 1639-4488
DOI - 10.1111/j.1751-908x.2006.tb00911.x
Subject(s) - chromium , xanes , hexavalent chromium , chemistry , extraction (chemistry) , environmental chemistry , contamination , genetic algorithm , soil contamination , nuclear chemistry , soil water , geology , chromatography , soil science , spectroscopy , ecology , physics , organic chemistry , quantum mechanics , evolutionary biology , biology
The oxidation states of chromium in GSJ JSO‐2 (artificially contaminated soil) and three other geochemical reference materials (GSJ JSO‐1, JLS‐1 and JMS‐1) were observed using X‐ray near edge structure (XANES). For comparison, other artificially contaminated soil materials (mimic‐JSO‐2) were prepared by adding Cr(VI) into JSO‐1. Their oxidation states of chromium were determined using XANES. The chromium contents were 1118 μg g ‐1 for JSO‐2, 1352 μg g ‐1 for mimic‐JSO‐2 and 69‐113 μg g ‐1 for the other reference materials. Most chromium was present as hexavalent in mimic‐JSO‐2. No hexavalent species were detected in other samples. These results for chromium oxidation state in JSO‐2 and mimic‐JSO‐2 obtained with XANES resembled those obtained from a chemical extraction method. The present JSO‐2 has no trace of Cr(VI), although Cr(VI) was added as a major species during preparation. On the other hand, the content of Cr(VI) obtained in mimic‐JSO‐2 agreed with the original Cr(VI) content. A time‐elapse study showed that Cr(VI) contents in mimic‐JSO‐2 decreased gradually to 70% of the original abundance during 240‐day preservation in dry conditions. Moreover, the abundance of Cr(VI) decreased markedly to 15% after 240 days in the wet mimic‐JSO‐2 containing 20% m/m of water. These experiments suggested that soil humidity enhanced the reduction of Cr(VI) and that Cr(VI) was reduced even in dry conditions. Consequently, it is reasonable to infer that Cr(VI) doped into JSO‐2 was completely reduced to Cr(III) during the preservation period of 5 years. The certification of the long‐term stability of the chemical form in reference materials will be much more important in future.