Isotopic Fingerprints of Iron Cyanide Complexes in the Environment

authors

  • Mansfeldt Tim
  • Höhener Patrick

document type

ART

abstract

Tracing the origin of iron cyanide complexes in the environment is important because these compounds are potentially toxic. We determined the stable isotopic compositions of cyanide carbon (C-CN) and cyanide-nitrogen (N-CN) in 127 contaminated solids and 11 samples of contaminated groundwater from coal carbonization sites, blast furnace operations, and commercial cyanide applications. Coal-carbonization-related cyanides had unique high mean delta C-13(CN) values of -10.5 +/- 3.5 parts per thousand for the solids and -16.1 +/- 1.2 parts per thousand for the groundwater samples, while the values for blast furnace sludge (-26.9 +/- 1.5 parts per thousand), commercial cyanides (-26.0 +/- 3.0 parts per thousand), and their corresponding groundwaters were significantly lower. Determination of delta C-13(CN) is a promising tool for identifying the source of cyanide contamination. However, for coal carbonization sites, historical research into the manufacturing process is necessary because a nonconventional gas works site exhibited exceptionally low delta C-13(CN) values of -22.7 +/- 1.7 parts per thousand. The delta N-15(CN) values for samples related to coal carbonization and blast furnaces overlapped within a range of +0.1 to +10.3 parts per thousand, but very high delta N-15(CN) values seemed to be indicative for a cyanide source in the blast furnace. In contrast, commercial cyanides tend to have lower delta N-15(CN) values of -5.6 to +1.9 parts per thousand in solids and -0.5 to +3.0 parts per thousand in the groundwater.

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