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21.
Kazuhiko Sakamoto Hisae Takada Kazuhiko Sekiguchi 《Atmospheric environment (Oxford, England : 1994)》2004,38(40):6961
To evaluate the influences of O3, relative humidity (RH), and flow rate on the reaction between yellow sand and SO2, the SO2 deposition velocity and the oxidation state of sulfur were investigated by means of exposure experiments in a cylindrical flow reactor. Early in the reaction, the deposition velocity was not influenced by the RH or the presence of O3; as the reaction progressed, however, the deposition velocity increased in the presence of O3 and at high humidity. The oxidation of sulfur from S(IV) to S(VI) was also enhanced under these conditions. The amount of sulfur oxidation was positively correlated with the amount of deposited O3. Furthermore, the SO2 deposition velocity increased with increasing flow rate. However, changes in the flow rate had no noticeable effect on the amount of SO2 oxidation. 相似文献
22.
Yugo Nomura Kazuo Fujiwara Makoto Takada Satoshi Nakai Masaaki Hosomi 《Journal of Material Cycles and Waste Management》2008,10(1):14-18
In previous studies, we focused on a mechanochemical process for recycling fly ash for use in cement; this process was expected
to immobilize heavy metals in the fly ash, a desirable outcome in light of the fact that recycled fly ash is commonly used
in the synthesis of inorganic materials. Here, we investigated the leaching of lead (Pb) from fly ash treated by a mechanochemical
process and from cement prepared from the treated fly ash. We used lead oxide (PbO), a typical Pb compound in fly ash, as
a model substance. Mechanochemical treatment of the fly ash inhibited Pb leaching by 93%, and further inhibition (more than
99.9%) was observed in cement produced from the treated fly ash. During the mechanochemical treatment, PbO was reduced to
Pb by iron from the stainless-steel mill used for processing, and the lower solubility of Pb in water resulted in immobilization
of the Pb. 相似文献
23.
Kobayashi J Kinoshita K Mizukawa K Sakurai T Imaizumi Y Takada H Suzuki N 《Chemosphere》2011,82(5):745-750
To evaluate the dietary uptake of polychlorinated biphenyls (PCBs) from live food, we investigated the dietary uptake and depuration kinetics of PCBs in a marine benthic fish (marbled sole, Pseudopleuronectes yokohamae) by using as food live sandworms (Perinereis nuntia) that were laboratory-exposed to field-collected PCB-contaminated sediment. Marbled sole were fed the PCB-contaminated sandworms for 28 d and then uncontaminated sandworms for 56 d. The assimilation efficiencies (AEs) of 84 PCB congeners via the gastrointestinal tract (GIT) to the muscle of the fish ranged from 0.21 to 0.78; whole-body AEs would be lower than those of muscle because of the lower PCB concentrations, on a lipid basis. The AEs determined in this study were lower than those in other studies that used PCB-spiked commercial pelletized food. The lower AEs found in this study might be attributable to differences in the food administered (live sandworms vs. commercial pellet food), possibly because of low digestibility of sandworm lipids by marbled sole. In addition, the AEs in this study tended to increase with increasing log octanol-water partition coefficients (KOW) up to about seven, although AEs in the other studies using commercial pelletized food did not increase with increasing log KOW. This result suggests the co-transport of highly hydrophobic PCB congeners along with lipids and fatty acids from the digested sandworms into the GIT epithelium cells. The growth-corrected half-lives of 26 PCB congeners in the muscle of fish ranged from 20 to 107 d. 相似文献
24.
We investigated perfluorinated surfactants (PFSs) in size-fractionated street dust to identify their occurrence, contributions from traffic, and potential routes of entry into waters. Street dust was collected from residential areas and heavily trafficked areas in Tokyo and sorted into fine (<63 microm) and coarse fractions (63-2000 microm). Five PFS species were analyzed by liquid chromatography-tandem mass spectrometry: perfluorooctanesulfonate (PFOS), perfluorooctanoate (PFOA), perfluorononanoate (PFNA), perfluorodecanoate (PFDA), and perfluoroundecanoate (PFUA). In fine fractions, PFS contents were significantly higher in heavily trafficked street dust than in residential street dust, but in coarse fractions, no significant differences were observed. Additionally, in heavily trafficked areas, PFS contents were significantly higher in fine fractions than in coarse fractions, but in residential areas, no significant differences were observed. PFS compositions differed between size fractions, not locations, indicating differences in sources between size fractions. Fine particles from traffic contributed to PFSs in street dust. Street dust possibly acts as the origin of PFSs in street runoff and eventually enters waters. This is the first report of PFSs in street dust. 相似文献
25.
The contribution of non-point sources to perfluorinated surfactants (PFSs) in a river was evaluated by estimating their fluxes and by using boron (B) as a tracer. The utility of PFSs/B as an indicator for evaluating the impact of non-point sources was demonstrated. River water samples were collected from the Iruma River, upstream of the intake of drinking water treatment plants in Tokyo, during dry weather and wet weather, and 13 PFSs, dissolved organic carbon (DOC), total nitrogen (TN), and B were analyzed. Perfluorohexane sulfonate (PFHxS), perfluorooctane sulfonate (PFOS), perfluoroheptanoate (PFHpA), perfluorooctanoate (PFOA), perfluorononanoate (PFNA), perfluorodecanoate (PFDA), perfluoroundecanoate (PFUA), and perfluorododecanoate (PFDoDA) were detected on all sampling dates. The concentrations and fluxes of perfluorocarboxylates (PFCAs, e.g. PFOA and PFNA) were higher during wet weather, but those of perfluoroalkyl sulfonates (PFASs, e.g. PFHxS and PFOS) were not. The wet/dry ratios of PFSs/B (ratios of PFSs/B during wet weather to those during dry weather) agreed well with those of PFS fluxes (ratios of PFS fluxes during wet weather to those during dry weather), indicating that PFSs/B is useful for evaluating the contribution from non-point sources to PFSs in rivers. The wet/dry ratios of PFOA and PFNA were higher than those of other PFSs, DOC, and TN, showing that non-point sources contributed greatly to PFOA and PFNA in the water. This is the first study to use B as a wastewater tracer to estimate the contribution of non-point sources to PFSs in a river. 相似文献
26.
Concentration changes of PCDDs, PCDFs, and dioxin-like PCBs in human breast milk samples as shown by a follow-up survey 总被引:3,自引:0,他引:3
Breast milk is known to discharge dioxins from the human body. However, to date, no direct comparison has been made of the concentrations of dioxin analogues in breast milk obtained from identical population after successive deliveries. We present here follow-up survey results of PCDDs, PCDFs, and dioxin-like PCBs concentrations in human breast milk samples from 35 women living in Tokyo from whom samples had been obtained and analyzed to determine the corresponding concentrations in the past. The average concentrations of total PCDDs, PCDFs, dioxin-like PCBs were 8.5, 5.5, 11 TEQ pg/g fat for the first samples and 5.4, 4.0, 6.6 TEQ pg/g fat for the second samples, respectively. The degrees of reduction of total PCDDs and total dioxin-like PCBs were higher than that of total PCDFs because 1,2,3,7,8-PeCDD, 2,3,4,7,8-PeCDF and 3,3',4,4',5-PeCB (#126), which were the predominant congeners among PCDDs, PCDFs, and dioxin-like PCBs, respectively, had different degrees of reduction. Moreover we observed a significant increase of the concentrations of PCDDs, PCDFs, and dioxin-like PCBs in samples from three women in this follow-up survey, and the patterns of increased isomers differed among the three samples. It was conjectured that the increase of the concentrations was due mainly to dietary intake between deliveries. It is important for pregnant women to have a balanced diet to mitigate the exposure of infants to these chemicals. 相似文献