Degradation of monomethylmercury chloride by hydroxyl radicals in simulated natural waters.
The degradation of methylmercury chloride by hydroxyl radicals (*OH) has been investigated using nitrate photolysis from 285 to 800 nm with a 450 W Xenon lamp as the (*OH source. The identified products are Hg(2+), Hg(0), CHCl(3) and formaldehyde. The second-order rate constant at pH of 5 at room temperature was determined to be 9.83(+-0.66)x10(9) M(-1) x s(-1)using benzoic acid as the *OH scavenger. The effects of chloride concentration and methylmercury speciation have also been investigated. A mechanism of the CH(3)HgCl-*OH reaction has been proposed. The calculated methylmercury degradation rates in natural waters using the above rate constant were comparable to the in situ photodegradation rates reported previously, indicating that degradation by (*)OH may be one of the important pathways of methylmercury degradation in sunlit surface waters.
Chen
Jing
J
Department of Chemical and Environmental Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260, Singapore.
Pehkonen
Simo O
SO
Lin
Che-Jen
CJ
D004202:Disinfectants / Q000737:chemistry; D005557:Formaldehyde / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry*; D008767:Methylmercury Compounds / Q000737:chemistry*; D016877:Oxidants / Q000737:chemistry*; D010084:Oxidation-Reduction; D010782:Photolysis; D018508:Water Purification
D004202:Disinfectants; D008767:Methylmercury Compounds; D016877:Oxidants; D005557:Formaldehyde; D017665:Hydroxyl Radical; C004925:methylmercuric chloride