Contribution of transboundary air pollution to ionic concentrations in fog in the Kinki Region of Japan

To estimate the contribution of transboundary transported air pollutants from other Asian countries to Japan in ionic concentrations in fog water in March 2005, the Community Multiscale Air Quality (CMAQ) modeling system was utilized with meteorological fields produced by the 5th generation Mesoscale Model (MM5). For meteorological predictions, the model well reproduced the surface meteorological variables, particularly temperature and humidity, and generally captured fog occurrence. For chemical predictions, most of the model-predicted monthly mean concentrations were approximately within a factor of 2 of the observations, indicating that the model well simulated the long-range atmospheric transport from the Asian Continent to Japan. For SO₄^2?, NO₃^? and NH₄⁺, the contribution rates of the transboundary air pollution in the Kinki Region of Japan ranged from 69 to 82% for aerosols, from 47 to 87% for ionic concentrations in rain, and from 55 to 79% for ionic concentrations in fog. The study found that the transboundary air pollution also affected ionic concentrations in fog as well as aerosol concentrations and ionic concentrations in rain.     

Reactivity between PbSO4 and CaCO3 particles relevant to the modification of mineral particles and chemical forms of Pb in particles sampled at two remote sites during an Asian dust event

During the transboundary transport of anthropogenic heavy metals by mineral particles providing reaction sites, the divalent metal salt PbSO₄ can be converted to PbCO₃ in the presence of water. We carried out laboratory experiments to study the transformation process under various conditions by incorporating test particles comprising CaCO₃ of a particulate mineral component, PbSO₄, and NaCl. After the immersion of PbSO₄ particles in contact with CaCO₃ particles in a water droplet, the conversion of PbSO₄ into PbCO₃ was confirmed by the change in morphology of the original particles to stick or needle form; the percentages of the chemical forms relative to the total Pb were determined by X-ray absorption near edge structure (XANES) analysis. Approximately 60–80% of PbSO₄ was converted to PbCO₃ after 24 h. A small amount of stick particles was detected when NaCl particles attached to PbSO₄/CaCO₃ particles were exposed to air with a relative humidity (RH) of 80–90% for 24 h. XANES measurements of the samples revealed that the molar percentage of PbCO₃ relative to the total Pb content was 4%.Field experiments were also conducted to determine the chemical forms of the Pb particles during the Kosa (Asian dust storm) event. Samples were collected from two remote sites in Japan and Korea. The mass size distribution of Pb aerosols collected in Japan was bimodal with two peaks in the coarse mode; the enrichment factor of Pb suggested that its source was anthropogenic. Pb L3 edge XANES measurements of both samples indicated that they had similar shapes. These measurements also indicated that the major Pb components for the samples collected in Japan were PbO, PbSO₄ PbCl₂, and PbCO₃, with molar percentages of 44%, 30%, 21%, and 5%, respectively. No significant differences were found between the component ratios of the samples collected in Japan and Korea, suggesting that definite transformation did not occur during the transport of the Kosa particles from Korea to Japan. On the basis of these observations, we postulate that the transformation process either occurred mainly before the particles arrived at Korea or did not take place after the particles left continental Asia.     

Levels and regional trends of persistent organochlorines and polybrominated diphenyl ethers in Asian breast milk demonstrate POPs signatures unique to individual countries

Human breast milk samples collected in 2007–2008 from four countries, Vietnam (Hanoi), China (Beijing), Korea (Seoul) and Japan (Sendai, Kyoto and Takayama), were analyzed for persistent organic pollutants (POPs) such as dichlorodiphenyltrichloroethane and its metabolites (DDTs), chlordane-related compounds (CHLs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). Comparing with previous surveys, the present study indicates that the DDTs in breast milk from China and Vietnam had gradually decreased during the last decade, but were still 5–10 times higher than those in other nations. The ratios of p,p′-DDE/p,p′-DDT and o,p′-DDT/p,p′-DDT were higher in Beijing than in the other countries, suggesting that there is less fresh intake of commercial DDT products and a possible exposure to dicofol in China. CHL and PCB levels were relatively higher in mothers from Japan, whereas β-HCH and HCB were more common in Chinese women. In Japan, it is suspected that mothers in the urban/coastal area (Sendai) were more continuously exposed to organochlorine pesticides (OCPs) than mothers in the rural/inland area (Takayama). In addition, OCP levels in primiparae were significantly higher than those in multiparae from Japan and Korea. These indicate that both parity and regional factors are major determinants of the levels of OCPs and PCBs in human milk. On the other hand, higher concentrations of PBDEs were observed in mothers' milk from Korea. The congener was dominated by BDE-47 (43–54%), followed by BDE-153 (23–33%) in all regions except for Beijing where BDE-28 (23%) was relatively abundant. In Japanese breast milk, regional and parity-dependent distributions were not observed for PBDEs. Among PBDE congeners, age-dependency was observed for BDE-153, which was negatively correlated (p < 0.05) to the age of mothers in Kyoto (17 participants were housewives), while it increased with age in Sendai (10 participants were clerks). No such correlation was seen for BDE-47, indicating that BDE-47 was ingested and assimilated via different kinetics or routes from BDE-153 in Japan.     

Post furnace formation of PCDDs and PCDFs in MSWI: Observations in an incinerator installed with quench reactor

Reduction of dioxin emission by a quench reactor with lime spray was investigated in relation to post furnace formation pathways. Results showed that the quench reactor performed to supress post furnace reaction of precursor molecules to form selected congeners of PCDD and PCDF.     

Modeling the influence of biogenic volatile organic compound emissions on ozone concentration during summer season in the Kinki region of Japan

Tropospheric ozone adversely affects human health and vegetation, and biogenic volatile organic compound (BVOC) emission has potential to influence ozone concentration in summer season. In this research, the standard emissions of isoprene and monoterpene from the vegetation of the Kinki region of Japan, estimated from growth chamber experiments, were converted into hourly emissions for July 2002 using the temperature and light intensity data obtained from results of MM5 meteorological model. To investigate the effect of BVOC emissions on ozone production, two ozone simulations for one-month period of July 2002 were carried out. In one simulation, hourly BVOC emissions were included (BIO), while in the other one, BVOC emissions were not considered (NOBIO). The quantitative analyses of the ozone results clearly indicate that the use of spatio-temporally varying BVOC emission improves the prediction of ozone concentration. The hourly differences of monthly-averaged ozone concentrations between BIO and NOBIO had the maximum value of 6 ppb at 1400 JST. The explicit difference appeared in urban area, though the place where the maximum difference occurred changed with time. Overall, BVOC emissions from the forest vegetation strongly affected the ozone generation in the urban area.     

Chlordane residues in krill,fish and Weddell seal from the Antarctic

Chlordane compounds (CHLs) were quantitated in krill (Euphausia superba), benthic fish (Trematomus bernacchii) and Weddell seal (Leptonychotes weddelli) collected around the Japanese Antarctic Research Station (Syowa Station: 69°00'S, 39°35'E). The concentrations of ZCHL (cis‐, trans‐chlordane+ cis‐, fraws‐nonachlor + oxych‐lordane) in krill was much lower than that of benthic fish. The ratio of SCHL to sum of SCHL, SDDT and PCBs decreased with the trophic levels. These results indicate that CHLs appear to be easily degraded in higher organisms.     

Acetate biodegradation by anaerobic microorganisms at high pH and high calcium concentration

Acetate biodegradation at a high pH and a high calcium concentration was examined to clarify the effect of bacterial activity on the migration of organic ¹⁴C compounds in cementitious repositories.Tamagawa river sediment or Teganuma pond sediment was anaerobically cultured with 5 mM acetate and 10 mM nitrate at pH 9.5-12 at 30 °C. After 20 and 90 days, the acetate concentration of the culture medium was analyzed and found to have decreased below 5 mM at pH ≤ 11. On the other hand, it did not decrease when either sediment was incubated in the absence of nitrate. These results suggest that nitrate-reducing bacteria can biodegrade acetate under more alkaline conditions than the reported pH range in which nitrate-reducing bacteria can exhibit activity.Acetate biodegradation was also examined at a high calcium concentration. Sediments were anaerobically cultured at pH 9.5 with 5 mM acetate and 10 mM nitrate in solution, equilibrated with ordinary Portland cement hydrate, in which the Ca concentration was 14.6 mM. No decrease in acetate concentration after incubation of the sediments was observed, nor was it lower than in the absence of cementitious composition, suggesting that kinetics of acetate biodegradation by anaerobic microorganisms is lowered by a high Ca concentration.     

Leaching of heavy metals by citric acid from fly ash generated in municipal waste incineration plants

The leaching behavior of heavy metals from municipal waste incineration (MWI) fly ash was investigated in this study. The leaching process includes two steps, i.e., fly ash was firstly washed with water, and then subjected to citric acid leaching. The main parameters of the washing process such as liquid/solid ratio, washing time, and number of washing were tested. The optimum conditions for water washing were found as follows: washing time 5–10 min, liquid/solid ratio 10:1 (ml:g), and number of washing was twice; under these conditions, 86% Na, 70% K, 12% Ca, 1.2% Al, and 0.5% Pb were removed from the fly ash in the prewashing. From the results of screening tests of leaching lixiviants, citric acid was found to be the most effective leaching agent, taking account of its environmentally benign characteristics. Optimum metal extraction can be achieved with citric acid under the following conditions: pH 3.0, liquid/solid ratio 40 (ml:g), citric acid concentration 0.10 mol/dm³, contact time 20 min at room temperature.