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Archives of Toxicology

, Volume 67, Issue 5, pp 365–368 | Cite as

Degradation of methyl and ethyl mercury by singlet oxygen generated from sea water exposed to sunlight or ultraviolet light

  • Ikuo Suda
  • Mari Suda
  • Kimiko Hirayama
Short Communication

Abstract

Photodegradation of methyl mercury (MeHg) and ethyl Hg (EtHg) in sea water was studied by sunlight or ultraviolet (UV) light exposure, and by determining inorganic Hg produced by degradation. Sea water containing 1 μM MeHg or EtHg was exposed to sunlight or UV light. N-Acetyl-l-cysteine was added to the solution for preventing Hg loss during the light exposure. MeHg and EtHg in sea water were degraded by sunlight (>280 nm), UV light A (320–400 nm) and UV light B (280–320 nm), though the amounts of inorganic Hg produced from MeHg were 1/6th to 1/12th those from EtHg. Inorganic Hg production was greater with increasing concentration of sea water. Degradation of MeHg and EtHg by the UV light A exposure was inhibited by singlet oxygen (1O2) trappers such as NaN3, 1,4-diazabicyclo[2,2,2]octane, histidine, methionine and 2,5-dimethylfuran. On the other hand, inhibitors or scavengers of Superoxide anion, hydrogen peroxide or hydroxyl radical did not inhibit the photodegradation of alkyl Hg. These results suggested that (1O2) generated from sea water exposed to sunlight, UV light A or UV light B was the reactive oxygen species mainly responsible for the degradation of MeHg and EtHg.

Key words

Methyl mercury Ethyl mercury Reactive oxygen Photodegradation Sunlight 

Abbreviations

Hg

mercury

MeHg

methyl mercury

EtHg

ethyl mercury

O2

superoxide anion

H2O2

hydrogen peroxide

· OH

hydroxyl radical

1O2

singlet oxygen

NAC

N-acetyl-l-cysteine

UV

ultraviolet

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Copyright information

© Springer-Verlag 1993

Authors and Affiliations

  • Ikuo Suda
    • 1
  • Mari Suda
    • 1
  • Kimiko Hirayama
    • 2
  1. 1.Kyushu National Agricultural Experiment StationMAFFNishigoshi KumamotoJapan
  2. 2.Kumamoto University College of Medical ScienceKumamotoJapan

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