Characteristics of azaarenes and dioxins in gases emitted from waste incinerators

In this study, we propose an analytical method to determine the fourteen of azaarenes present in flue gas samples collected according to Japanese Industrial Standard K 0311, which designates the method for the determination of dioxins in flue gas. Azaarenes can be analyzed using the acidic water phase after shaking extraction with dichloromethane, which is unnecessary for dioxin analysis. Flue gas samples were obtained from 24 waste incinerators in Japan, and azaarenes were detected in all the flue gas samples (0.21–3800 μg/m³ _N). The most abundant of the detected compounds were quinoline and isoquinoline. The concentration of azaarenes had a tendency to increase with that of polychlorinated dibenzo-p-dioxins and dibenzofurans. The isomer distribution of heptachloro-dibenzofurans (HpCDFs) was calculated using the computed Gibbs energy of formation (ΔG _f ) obtained by the semiempirical molecular orbital method at various temperatures. The calculated isomer distribution was fitted to the measured value of HpCDFs. It seems that the temperature obtained from the fitting calculations is an indicator of the cooling capacity of the combustion gas in an incinerator. The computed ΔG _f also explained the measured isomer distributions of azaarenes. It is suggested that the isomer distribution of azaarenes in the combustion process is thermodynamically controlled. This work was presented in part at the International Conference on Combustion, Incineration/Pyrolysis, and Emission Control, 2006, Kyoto     

Quantitative assessment of the Japanese “local production for local consumption” movement: a case study of growth of vegetables in the Osaka city region

This study aimed to assess Japan’s recent “local production for local consumption” (LPLC) movement, with a special focus on vegetables in the Osaka city region of central Japan. After collecting statistics and spatial data, we conducted a multi-scale analysis of vegetable production and consumption along with the associated energy consumption, using geographical information system software at three spatial scales along the vegetable flow paths: national, regional, and local. Vegetables consumed in the Osaka city region came from prefectures throughout Japan, and we mapped the foodshed within this region at 1-km spatial resolution, as well as the distribution of farmland, farmers’ and other markets. We also conducted a scenario analysis for reduced energy consumption through organic farming and the utilization of abandoned farmland near a city to replace food imports from distant areas. We found that the large majority of vegetables consumed in the Osaka city region currently come from remote prefectures, and that this is associated with a high level of energy consumption. Inside the Osaka city region, peri-urban vegetable farming contributes to regional vegetable provision, resulting in an approximately 70 % production/consumption ratio within an 80-km radius of the urban center; if all of the area of abandoned farmland were restored to production, this ratio would increase to approximately 75 %. Organic farming activities that bring together farmers and urbanites are emerging in many parts of the study area, contributing to increased LPLC. Scenario analysis suggested that a decrease of more than 1 × 10⁶ GJ of energy inputs could be achieved through wider adoption of local organic farming for local consumption and complete utilization of abandoned farmland in the Osaka city region.     

Emission control for precursors causing acid rain (V): Improvement of acid soil with the bio-briquette combustion ash

The bio-briquette technique which mixes coal, biomass and sulfur fixation agent and bio-briquettes under 3-5 t/cm^2 line pressure has aroused people‘s attention in view of controlling the air pollution and the acid rain. In this paper, the physicochemical properties of bio-briquette and its ash were investigated. And the acid soil was improved by the bio-briquette combustion ash, which contained nutritive substances such as P, N, K and had the acid-neutralizing capacity(ANC). The pH, EC, effective nutrient elements(Ca, Mg, K, P and N), heavy metal elements(AI, Cu, Cd, Cr, Zn and Mn) and acid-neutralizing capacity change of ash-added soils within the range of 0-10%, were also studied. Specially, when 5% bio-briquette combustion ash was added to the tested soil, the content of the effective elements such as Ca, Mg and K rose by 100 times, ? times and twice, respectively. The total nitrogen also increased by about twice. The results showed the oxyanions such as that of AI, Cu, Cd, Cr, Zn and Mn were not potentially dangerous, because they were about the same as the averages of them in Chinese soil. It is shown that the ANC became stronger, though the ANC hardly increases in the ash-added soil. On the basis of the evaluation indices, it is concluded that the best mixture ratio is to add 2.5%--8% of the bio-briquette combustion ash to the tested soil.     

Accumulation of cadmium and zinc in <Emphasis Type="Italic">Evodiopanax innovans</Emphasis>

The use of tree species for phytoremediation of contaminated soil offers the advantage of a large biomass in which to store contaminants. We investigated the cadmium (Cd) and zinc (Zn) accumulation ability of Evodiopanax innovans, a common deciduous tree species belonging to the Araliaceae family and widely found in secondary forests in Japan. Sampling was conducted at an old silver mine. Leaf samples were collected from nine tree species, including E. innovans. The seasonal variation of metal concentrations in the leaves and the detailed distribution of metals in the leaves and twigs of E. innovans were measured. We also analyzed the contents of organic acids in the leaves. The highest concentration of Cd in the leaves of E. innovans was 118 μg/g, which exceeds the threshold level for being considered a Cd hyperaccumulator (100 μg/g). For Zn, the highest value was 1040 μg/g in leaves, which is less than required to qualify as a Zn hyperaccumulator. Both Cd and Zn were found to accumulate in the petioles and veins of leaves and the bark of twigs. Since the oxalic acid content of leaves showed a weak correlation with Cd concentration, oxalic acid may play an important role in the accumulation of Cd. Taking both the Cd concentration level and the biomass of this woody plant into consideration, it may be possible to use E. innovans for the phytoremediation of Cd-contaminated soils.     

Efficient depolymerization and chemical conversion of polyamide 66 to 1,6-hexanediol

Journal of Material Cycles and Waste Management - Polyamide 66 was efficiently depolymerized and chemically converted by treatment with supercritical MeOH in the presence of glycolic acid. The...     

Heterogeneous loss of HO2 by KCl,synthetic sea salt,and natural seawater aerosol particles

The HO₂ uptake to aerosol particles is potentially significant sink for the HO₂ radical in the marine atmosphere. To assess the heterogeneous loss of HO₂ on marine aerosol particles, we have investigated the uptake coefficients (γ) of HO₂ for submicron aerosol particles of KCl, synthetic sea salt, and natural seawater under ambient conditions (760 Torr and 296 ± 2 K) using an aerosol flow tube (AFT) coupled with a chemical conversion/laser-induced fluorescence (CC/LIF) technique. γ values determined for dry and wet aerosols of KCl were 0.02 ± 0.01 and 0.07 ± 0.03 at 66% and 75% RH, respectively, while γ values for those doped with CuSO₄ was 0.55 ± 0.19 at 75% RH. γ values determined for synthetic sea-salt particles were 0.07 ± 0.03, 0.12 ± 0.04 and 0.13 ± 0.04 at 35%, 50%, 75% RH, respectively, while γ values for natural seawater particles were 0.10 ± 0.03, 0.11 ± 0.02 and 0.10 ± 0.03 at 35%, 50%, 75% RH, respectively. We recommend a HO₂ uptake coefficient in marine areas of 0.1 for modeling and estimated the contribution of heterogeneous loss of HO₂ by sea-salt aerosol particles in marine areas using a box model. Our box-model simulations suggested that daytime maximum HO₂ concentrations decreased to 87–94% of the values without heterogeneous loss.     

Contributions of biogenic volatile organic compounds to the formation of secondary organic aerosols over Mt. Tai,Central East China

To better understand the contribution of biogenic volatile organic compounds to the formation of secondary organic aerosol (SOA) in high mountain regions, ambient aerosols were collected at the summit of Mt. Tai (1534 m, a.s.l.), Central East China (CEC) during the Mount Tai Experiment 2006 campaign (MTX2006) in early summer. Biogenic SOA tracers for the oxidation of isoprene, α/β-pinene, and β-caryophyllene were measured using gas chromatography/mass spectrometry. Most of the biogenic SOA tracers did not show clear diurnal variations, suggesting that they are formed during long-range atmospheric transport or over relatively long time scales. Although isoprene- and α/β-pinene-derived SOA tracers did not correlate with levoglucosan (a biomass burning tracer), β-caryophyllinic acid showed a good correlation with levoglucosan, indicating that crop residue burning may be a source for this acid. Total concentrations of isoprene oxidation products are much higher than those of α/β-pinene and β-caryophyllene oxidation products. The averaged ratio of isoprene to α/β-pinene oxidation products (R_iso/pine) was 4.9 and 6.7 for the daytime and nighttime samples, respectively. These values are among the highest in the aerosols reported in different geographical regions, which may be due to the large isoprene fluxes and relatively high levels of oxidants such as OH in CEC. Using a tracer-based method, we estimated the concentrations of secondary organic carbon (SOC) derived from isoprene, α/β-pinene, and β-caryophyllene to be 0.42–3.1 μgC m^?3 (average 1.6 μgC m^?3) during the daytime and 0.11–4.2 μgC m^?3 (1.7 μgC m^?3) during the nighttime. These values correspond to 2.9–23% (10%) and 3.2–28% (9.8%) of the total OC concentrations, in which isoprene-derived SOC accounts for 58% and 63% of total SOC during the daytime and nighttime, respectively. This study suggests that isoprene is a more significant precursor for biogenic SOA than α/β-pinene and β-caryophyllene at high altitudes in CEC.     

Polychlorinated dibenzothiophenes in Japanese environmental samples and their photodegradability and dioxin-like endocrine-disruption potential

Polychlorinated dibenzothiophenes (PCDTs) in sediment, soil, and fly ash samples collected in Japan were analyzed and their dioxin-like endocrine-disruption potential and photodegradability investigated. PCDTs were detected in all three types of sample, although the concentrations were lower than those of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). An Ah-immunoassay confirmed that 2,3,7,8-TeCDT, 1,2,3,7,8-PeCDT, 1,2,3,7,8,9-HxCDT, and 1,2,3,4,7,8,9-HpCDT had Ah receptor-binding activities, which means that these PCDTs have the potential to cause dioxin-like endocrine-disruption. Photodegradation of PCDTs by UV irradiation was accompanied by dechlorination. The photodegradation rates of 2,3,7,8-TeCDT and OCDT were lower than the rates for the corresponding PCDF isomers (2,3,7,8-TeCDF and OCDF), which indicates that PCDTs are more stable than PCDFs to photodegradation.     

Estimation of municipal solid waste generation and landfill area in Asian developing countries

In developing Asian countries, the municipal cooperations are unable to handle the increasing amount of municipal solid waste, which into the uncollected waste being spread on roads and in other public areas leading to tremendous pollution and destruction of land and negative impact on human health. Generation of municipal solid waste increases with the rapid urbanization and accelerated economic development with in the rapidly growing advanced technological societies. The nature of municipal solid waste is a term usually applied to a heterogeneous collection group of waste produced in urban areas, the nature of which varies from region to region. The common problem faced by all developing Asian countries, is the disposal of municipal solid waste and availability of land fill site area. Present study explains the correlation analysis of among different factors of municipal solid waste and the objective is to assess the future municipal solid waste stream in Asian developing countries. The other goal of this study was to calculate the future land area that would be required for landfill site disposal in Asian developing countries.     

Dietary contribution of the microphytobenthos to infaunal deposit feeders in an estuarine mudflat in Japan

The food sources of benthic deposit feeders were investigated at three stations in an estuarine mudflat (Idoura Lagoon, Sendai Bay, Japan) during July and August 2005, using δ¹³C and δ¹⁵N ratios. Sediment at the stations was characterized by low chlorophyll (chl) a content (0–1 cm depth, <4 μg cm⁻²) and the dominance of riverine–terrestrial materials (RTM) in the sediment organic matter (SOM) pool. Surface-deposit feeders (Macoma contabulata, Macrophthalmus japonicus, and Cyathura muromiensis) exhibited much higher δ¹³C values (−18.4 to −12.4‰) than did the SOM pool (<−25‰). A δ¹³C-based isotopic mixing model estimated that benthic diatoms comprised 45–100% (on average) of their assimilated diet, whereas RTM comprised a lesser fraction (29% maximum). The major diet of the deep-deposit feeding polychaetes Notomastus sp. and Heteromastus sp. was benthic diatoms and/or marine particulate organic matter (POM), with little RTM assimilated (39% maximum). The consumers appeared to lack specific digestive enzymes and to use detritus-derived carbon only after its transfer to the microbial biomass. The isotopic mixing model also showed that the dietary contribution of RTM increased slightly (15% maximum) in the vicinity of freshwater input, suggesting that spatial changes in RTM supply affect the dietary composition of deposit feeders. These results clearly demonstrate that deposit feeders selectively ingest and/or assimilate the more nutritious microalgal fractions in the SOM pool. Such adaptations may allow enhanced energy gain in estuarine mudflats that are rich in vascular plant detritus with low nutritive value.