TY - JOUR
T1 - Hydrogen Cyanide Accumulation and Transformations in Non-polluted Salt Marsh Sediments
AU - Kamyshny, A.
AU - Oduro, H.
AU - Mansaray, Z. F.
AU - Farquhar, J.
N1 - Funding Information:
Acknowledgments This work was supported by the Max Planck Society (T.G.F. and A.K.), Marie Curie Outgoing International Fellowship SULFUTOPES number POIF-GA-2008-219586 (to A.K.), NSF Geobiology and Low Temperature Geochemistry Program grant number: 0843814 (to A. K., JF and Z.F.M.) and the NASA Astrobiology Institute (J.F.). The authors would like to thank George W. Luther and Andrew Madison (University of Delaware) for assistance during sampling of Delaware Great Marsh. The authors are grateful to Donald E. Canfield and Daniel L. Eldridge for valuable comments on the manuscript. The revised manuscript benefited by the comments of two anonymous reviewers and the Associated Editor David J. Burdige.
PY - 2013/3/1
Y1 - 2013/3/1
N2 - While cyanide is known to be produced by many organisms, including plants, bacteria, algae, fungi and some animals, it is generally thought that high levels of cyanide in aquatic systems require anthropogenic sources. Here, we report accumulation of relatively high levels of cyanide in non-polluted salt marsh sediments (up to 230 μmol kg-1). Concentrations of free cyanide up to 1. 92 μmol L-1, which are toxic to aquatic life, were detected in the pore-waters. Concentration of total (free and complexed) cyanide in the pore-waters was up to 6. 94 μmol L-1. Free cyanide, which is released to the marsh sediments, is attributed to processes associated with decomposition of cord grass, Spartina alterniflora, roots and possibly from other sources. This cyanide is rapidly complexed with iron and adsorbed on sedimentary organic matter. The ultimate cyanide sink is, however, associated with formation of thiocyanate by reaction with products of sulfide oxidation by Fe(III) minerals, especially polysulfides. The formation of thiocyanate by this pathway detoxifies two poisonous compounds, polysulfides and hydrogen cyanide, preventing release of free hydrogen cyanide from salt marsh sediments into overlying water or air.
AB - While cyanide is known to be produced by many organisms, including plants, bacteria, algae, fungi and some animals, it is generally thought that high levels of cyanide in aquatic systems require anthropogenic sources. Here, we report accumulation of relatively high levels of cyanide in non-polluted salt marsh sediments (up to 230 μmol kg-1). Concentrations of free cyanide up to 1. 92 μmol L-1, which are toxic to aquatic life, were detected in the pore-waters. Concentration of total (free and complexed) cyanide in the pore-waters was up to 6. 94 μmol L-1. Free cyanide, which is released to the marsh sediments, is attributed to processes associated with decomposition of cord grass, Spartina alterniflora, roots and possibly from other sources. This cyanide is rapidly complexed with iron and adsorbed on sedimentary organic matter. The ultimate cyanide sink is, however, associated with formation of thiocyanate by reaction with products of sulfide oxidation by Fe(III) minerals, especially polysulfides. The formation of thiocyanate by this pathway detoxifies two poisonous compounds, polysulfides and hydrogen cyanide, preventing release of free hydrogen cyanide from salt marsh sediments into overlying water or air.
KW - Hydrogen cyanide
KW - Inorganic polysulfides
KW - Metallo-cyanide complexes
KW - Sulfide
KW - Sulfide oxidation intermediates
KW - Thiocyanate
UR - http://www.scopus.com/inward/record.url?scp=84874364486&partnerID=8YFLogxK
U2 - 10.1007/s10498-012-9180-5
DO - 10.1007/s10498-012-9180-5
M3 - Article
AN - SCOPUS:84874364486
SN - 1380-6165
VL - 19
SP - 97
EP - 113
JO - Aquatic Geochemistry
JF - Aquatic Geochemistry
IS - 2
ER -
