Arsenic speciation in marine interstitial water. The occurrence of organoarsenicals |
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Authors: | K J Reimer J A Thompson |
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Institution: | (1) Dept. of Chemistry, Royal Roads Military College, FMO, Victoria, BC, Canada, V0S 1B0;(2) Institute of Ocean Sciences, P.O. Box 6000, Sidney, BC, Canada, V8L 4B2 |
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Abstract: | Arsenic speciation data are presented for pore waters squeezed from some native and anthropogenically influenced sediments.Ten stations were sampled with a box corer (to 20 cm) at two British Columbia coastal sites that are influenced by mine-tailings discharges. These are Rupert Inlet and Alice Arm as well as their associated systems of Quatsino Sound/Holberg Inlet and Hastings Arm respectively.Total dissolved arsenic concentrations ( As
D) usually exhibited subsurface maxima at 5–10 cm and were generally related to solid phase arsenic (As
p) levels, but there was also a dependence on the nature of the substrate. Tailings exhibited both the lowest (Rupert Inlet) and the highest (Alice Arm) As
D values. Inorganic arsenicals, arsenate (AsV) and arsenite (AsIII) constituted the majority (>90%) of the dissolved species butevery sample contained organoarsenicals. This is the first report of mono-, di- and tri-methylated arsenic species in marine interstitial water.A strong positive correlation between the sum of the methylarsenic compounds ( MeAs) and the total dissolved arsenic ( As
D) was found, indicating in situ microbial methylation similar to that observed in non-aquatic systems. Flux values for arsenic at the sediment-water interface suggest that, at present, there is no significant mobilization of arsenic from these mine-derived sediments into the water column. |
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Keywords: | arsenic speciation interstitial water organoarsenicals sediment mine-tailings Rupert Inlet Alice Arm |
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