title: Influence of aggregated particles on biodegradation activities for dimethylarsinic acid (DMA) in Lake Kahokugata.
abstract: Aquatic arsenic cycles mainly depend on microbial activities that change the arsenic chemical forms and influence human health and organism activities. The microbial aggregates degrading organic matter are significantly related to the turnover between inorganic arsenic and organoarsenic compounds. We investigated the effects of microbial aggregates on organoarsenic mineralization in Lake Kahokugata using lake water samples spiked with dimethylarsinic acid (DMA). The lake water samples converted 1 μmol L(-1) of DMA to inorganic arsenic for 28d only under anaerobic and dark conditions in the presence of microbial activities. During the DMA mineralization process, organic aggregates >5.0 μm with bacterial colonization increased the densities. When the organic aggregates >5.0 μm were eliminated from the lake water samples using filters, the degradation activities were reduced. DMA in the lake water would be mineralized by the microbial aggregates under anaerobic and dark conditions. Moreover, DMA amendment enhanced the degradation activities in the lake water samples, which mineralized 50 μmol L(-1) of DMA. The DMA-amended aggregates >5.0 μm completely degraded 1 μmol L(-1) of DMA with a shorter incubation time of 7d. The supplement of KNO(3) and NaHCO(3) to lake water samples also shortened the DMA-degradation period. Presumably, the bacterial aggregates involved in the chemical heterotrophic process would contribute to the DMA-biodegradation process in Lake Kahokugata, which is induced by the DMA amendment.
authors.affiliation: College of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa-shi, Japan. makiteru@t.kanazawa-u.ac.jp
authors.forename: Teruya
authors.initials: T
authors.lastname: Maki
authors.forename: Wakana
authors.initials: W
authors.lastname: Hirota
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Motojima
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hasegawa
authors.forename: Mohammad Azizur
authors.initials: MA
authors.lastname: Rahman
mesh_terms: D001419:Bacteria / Q000378:metabolism; D001673:Biodegradation, Environmental; D001711:Biotransformation; D002101:Cacodylic Acid / Q000032:analysis / Q000378:metabolism*; D005618:Fresh Water / Q000737:chemistry* / Q000382:microbiology; D006540:Herbicides / Q000032:analysis / Q000378:metabolism*; D059013:Microbial Consortia; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism*
chemical_list: D006540:Herbicides; D014874:Water Pollutants, Chemical; D002101:Cacodylic Acid