title: Physicochemical speciation of molybdenum in rain water.
abstract: A combination of a sensitive catalytic determination method with filtration and ultrafiltration has been used for the physicochemical speciation of molybdenum in natural and synthetic rain water samples. The concentration (CL) of labile molybdenum was evaluated by a direct catalytic determination. The total concentration (CT ) of molybdenum was determined after the acid decomposition of the sample to calculate the non-labile concentration (CT-CL). From the speciation results, molybdenum species in the successive rainfall sample were found in a fraction with smaller molecular weights < 10(3) Da and characterized as labile forms, i.e. simple molybdate ions. Non-labile molybdenum existed in particulate matter (> or = 0.45 microm in particle size) and distributed predominantly in the initial rainfall sample. The coprecipitation with Fe(III) hydroxide contributed to the formation of the non-labile molybdenum. In the initial rainfall sample, a small part of molybdenum was labile in the particle fraction (> or = 0.45 microm). This type of molybdenum was associated with the formation of humic iron aggregates.
authors.affiliation: Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Yamanashi University, Kofu-shi, Japan. kawakubo@ab11.yamanashi.ac.jp
authors.forename: S
authors.initials: S
authors.lastname: Kawakubo
authors.forename: S
authors.initials: S
authors.lastname: Hashi
authors.forename: M
authors.initials: M
authors.lastname: Iwatsuki
mesh_terms: D000393:Air Pollutants / Q000032:analysis* / Q000737:chemistry; D002384:Catalysis; D004784:Environmental Monitoring / Q000379:methods*; D005290:Ferric Compounds / Q000032:analysis / Q000737:chemistry; D005374:Filtration / Q000379:methods; D006812:Humic Substances / Q000032:analysis / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008956:Models, Chemical; D008970:Molecular Weight; D008982:Molybdenum / Q000032:analysis* / Q000737:chemistry; D010316:Particle Size; D011891:Rain; D014462:Ultrafiltration / Q000379:methods; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D005290:Ferric Compounds; D006812:Humic Substances; D014874:Water Pollutants, Chemical; C021024:ferric hydroxide; D008982:Molybdenum