Summer time haze characteristics of the urban atmosphere of Gwangju and the rural atmosphere of Anmyon, Korea

An extensive visibility monitoring was carried out simultaneously in the urban area of Gwangju and the rural area of Anmyon, Korea. This study examines patterns of visibility impairment and haze-forming pollutant concentrations on both sites resulting from natural and anthropogenic sources of gases and particles. Optical visibility measurements by a transmissometer, a nephelometer and an aethalometer provide aerosol light extinction, scattering, and absorption coefficients for both sites. In order to investigate the physico-chemical characteristics of atmospheric aerosols, aerosol samples were collected by various aerosol samplers at GJVMS (Gwangju Visibility Monitoring Station) and at KGAWO (Korea Global Atmosphere Watch Observatory), respectively. In addition, haze characteristics causing visibility impairment at those two sites were analyzed to obtain source contributions by regionally transported aerosols using grid analysis and display system (GrADS) from NECP reanalysis data. During the intensive monitoring period, ammonium sulfate was dominantly responsible for the fine particle mass loading at GJVMS, whereas organic carbon was the largest contributor at KGAWO. Light scattering by particles accounted for 52.8 to 81.3% of the range at the urban site, GJVMS and for 72.1 to 94.2% of the range at the rural site, KGAWO. Light absorption by the EC and NO₂ was between 14.5 and 34.8% at GJVMS, which was higher than the observed 1.1 ∼ 6.8% at KGAWO, respectively. Light scattering by aerosol was higher in the rural area than in the urban area. And organic carbon concentration was observed to be significantly higher than the concentration of elemental carbon at KGAWO. These haze-forming carbonaceous particles originate from anthropogenic pollutants at the urban atmosphere but they can be produced by natural environments such as marine and forest at the rural atmosphere.     

Enrichment of PCDDs/PCDFs in peripheral utilities of the municipal solid waste incineration facility

This study was performed to suggest the improvements through measuring the amounts of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), re-synthesized in peripheral utilities (PUs) of a commercial-scale municipal solid waste incineration facility (MSWIF) where a few research results existed. The PUs examined in this study consisted of air pre-heaters (APHs) and gas/gas re-heater (GGRH) and kerosene-fired duct burner for selective catalytic reduction (SCR) process. PCDDs/PCDFs in flue gas were simultaneously measured at the inlet and outlet of PUs.Flue gas was cooled down from 380 °C to 249 °C by exchanging the heat with fresh air in APHs, and then heated up to 383 °C by GGRH and duct burner from 164 °C at the outlet of bag filter. The results showed that PCDDs/PCDFs were 3–4 times higher within this temperature range of PUs. In comparison of PCDDs/PCDFs concentrations at the inlet with those at the outlet of PUs, particulate-phase PCDDs/PCDFs were about 9.5–10 times enriched while gaseous-phase ones were decreased by about 33–41%. The PCDDs/PCDFs re-synthesized in the PUs, where PCDDs were relatively higher than PCDFs, showed somewhat different patterns compared to those formed at incinerators and emitted at stack. Through the investigations for PUs, we conclude that the PUs used in MSWIFs was a potential source for de novo synthesis of PCDDs/PCDFs.     

Reducing ammonia emissions and volatile fatty acids in poultry litter with liquid aluminum chloride

This study was a pen trial in which the effects of adding different rates of liquid aluminum chloride (AlCl₃) on litter pH, total volatile fatty acids (VFAs), and ammonia (NH₃) fluxes was evaluated. Liquid AlCl₃ treatments used in this study were sprayed on the rice hull surface at rates of 100 g, 200 g, and 300 g liquid AlCl₃/kg rice hulls; untreated rice hulls served as controls. Litter pH, total VFAs, and NH₃ fluxes were all lowered (P< 0.05) by all of the liquid AlCl₃ treatments compared with controls during certain times of the 5 week study. However, there were no significant differences among treatments on litter pH at the end of the study (from 3 to 5 weeks) or NH₃ fluxes at beginning of the study (0 to 3 weeks). Total VFAs were reduced 16 %, 29 %, and 53 % by 100 g liquid AlCl₃/kg rice hulls, 200 g liquid AlCl₃/kg rice hulls, and 300 g liquid AlCl₃/kg rice hulls, respectively. Liquid AlCl₃additions reduced NH₃ fluxes by 35 %, 57 % and 67 %, respectively, at the low, medium and high rates. In summary, these results indicate that adding liquid aluminum chloride to rice hulls would be a useful tool in reducing the negative environmental impact of poultry litter. It should be noted that the decreased VFA production and NH₃ volatilization was chiefly associated with reduction in litter pH.     

An innovative modeling approach using Qual2K and HEC-RAS integration to assess the impact of tidal effect on River Water quality simulation

Water quality modeling has been shown to be a useful tool in strategic water quality management. The present study combines the Qual2K model with the HEC-RAS model to assess the water quality of a tidal river in northern Taiwan. The contaminant loadings of biochemical oxygen demand (BOD), ammonia nitrogen (NH₃-N), total phosphorus (TP), and sediment oxygen demand (SOD) are utilized in the Qual2K simulation. The HEC-RAS model is used to: (i) estimate the hydraulic constants for atmospheric re-aeration constant calculation; and (ii) calculate the water level profile variation to account for concentration changes as a result of tidal effect. The results show that HEC-RAS-assisted Qual2K simulations taking tidal effect into consideration produce water quality indices that, in general, agree with the monitoring data of the river. Comparisons of simulations with different combinations of contaminant loadings demonstrate that BOD is the most import contaminant. Streeter-Phelps simulation (in combination with HEC-RAS) is also performed for comparison, and the results show excellent agreement with the observed data. This paper is the first report of the innovative use of a combination of the HEC-RAS model and the Qual2K model (or Streeter-Phelps equation) to simulate water quality in a tidal river. The combination is shown to provide an alternative for water quality simulation of a tidal river when available dynamic-monitoring data are insufficient to assess the tidal effect of the river.     

Prenatal diagnosis of Hb H disease due to compound heterozygosity for South-East Asian deletion and Hb constant spring by polymerase chain reaction

A pregnant woman has two children affected by moderately severe Hb H disease due to compound heterozygosity of South-east Asian deletion and Constant Spring mutation. In her third pregnancy, transabdominal chorionic villus sampling was performed at the tenth gestational week to obtain fetal DNA. The polymerase chain reaction was used for detection of both the South-east Asian deletion and the Constant Spring mutation. Hb H disease was diagnosed in the fetus. After genetic counselling, the couple elected to have the pregnancy terminated.     

The changes in common carp blood after short-term zinc exposure

Blood zinc level, hematological parameters and blood cell morphology were evaluated in common carp immediately after 3 h exposure to 20 mg dm(-3) of zinc (Zn0), and in 24, 48 and 96 hours after the end of it (Zn24, Zn48, Zn96). Blood zinc level in the non-exposed fish was 8 mg dm(-3), reached a maximum of 20 mg dm(-3) in Zn48, while it dropped to 9 mg dm(-3) in Zn96. Zinc caused a stress reaction in fish indicated by an increase in hematocrit value in Zn0, and elevated plasma glucose level and trombocytosis which persisted until the end of the experiment. Zinc-exposed fish showed an increased frequency of abnormal erythrocytes, and a compensatory release of immature erythrocytes to the blood stream. In zinc-treated fish, leukocyte count initially increased and subsequently decreased significantly below the control level due to a drop in lymphocyte number. Lymphocyte viability was reduced, and abnormal lymphocytes appeared. A decreased count of juvenile neutrophiles, and reduced phagocyte activity also occurred. The results indicate possible zinc-induced disturbances in both specific and non-specific immune mechanisms.     

Emission characteristics of PCDD/Fs, PCBs, chlorobenzenes, chlorophenols, and PAHs from polyvinylchloride combustion at various temperatures

The effect of temperature on polyvinylchloride (PVC) combustion using a downstream tubular furnace was investigated for the formation of polycylcic aromatic hydrocarbons (PAHs) and chlorinated compounds. As the temperature increased, higher levels of PAHs were generated. Chlorinated compounds reached a peak at 600 degrees C, with low emissions recorded at 300 and 900 degrees C. There was a close correlation (R2 = 0.97) among polychlorinated biphenyls (PCBs), hexachlorobenzene, pentachlorobenzene, and polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). PAHs at all temperatures were analyzed in the gas phase. PCDD/Fs and PCBs were emitted as a solid phase at 300 and 600 degrees C and as a gas phase at 900 degrees C. For some PAHs, chlorobenzenes, and PCDD/Fs, a mathematical equation between the gas and solid phase and the reciprocal temperature in semilog proportion was derived. The proposed equation, which is log (amount in gas phase/amount in solid phase) = -A/T + B, where T is the temperature of the furnace and A and B are constants, for these species relating their gas/solid distributions showed a good relationship.     

Minute theropod eggs and embryo from the Lower Cretaceous of Thailand and the dinosaur-bird transition

We report on very small fossil eggs from the Lower Cretaceous of Thailand, one of them containing a theropod embryo, which display a remarkable mosaic of characters. While the surficial ornamentation is typical of non-avian saurischian dinosaurs, the three-layered prismatic structure of the eggshell is currently known only in extant and fossil eggs associated with birds. These eggs, about the size of a goldfinch's, mirror at the reproductive level the retention of small body size that was paramount in the transition from non-avian theropods to birds. The egg-layer may have been a small feathered theropod similar to those recently found in China.