The effects of wind speed on the relative relationships between different sized-fractions of airborne particles

The concentrations of three different size fractions of particulate matter (PM) including PM2.5, PM10, and TSP were determined continuously at hourly intervals from four different sites in Seoul, Korea during the spring of 2001. To learn the effects of wind speed change on PM fractionation, the entire data sets were initially sorted into three particle fractions such as: fine (F: PM2.5), coarse (C: PM10-PM2.5), and giant (G: TSP-PM10). The inter-fraction relationships of PM were then explored by linear regression analysis of the data divided into four wind speed regimes. The results of this analysis, when examined in terms of either relative dominance between different PM fractions (i.e., in terms of their slope values) or strength of correlations, indicate the existence of diverse inter-fraction patterns. Most importantly, the physical influence of wind speed is seen to be reflected most efficiently between fine and coarse particle fractions, as the relative contribution of coarse fraction to the mass concentration of total particles (e.g., PM10) changes proportionally with changes in wind speed. However, such systematic patterns decrease noticeably between fine and giant fractions, as they can be affected more sensitively by such factors as the nature of their sources or the surrounding environmental conditions. The results of our comparative analysis thus confirm that wind speed is a useful barometer to distinguish and predict the behavior of different particle fractions in relation to each other.     

Evidence of immunomodulation in nestling American kestrels (Falco sparverius) exposed to environmentally relevant PBDEs

We investigated whether exposure to environmentally relevant polybrominated diphenyl ethers (PBDEs) causes immunomodulation in captive nestling American kestrels (Falco sparverius). Eggs within each clutch, divided by laying sequence, were injected with safflower oil or penta-BDE congeners-47, -99, -100, and -153 dissolved in safflower oil (18.7 microg sigmaPBDEs/egg) approximating Great Lakes birds. For 29 days, nestlings consumed the same PBDE mixture (15.6+/-0.3 ng/g body weight per day), reaching sigmaPBDE body burden concentrations that were 120x higher in the treatment birds (86.1+/-29.1 ng/g ww) than controls (0.73+/-0.5 ng/g ww). PBDE-exposed birds had a greater PHA response (T-cell-mediated immunity), which was negatively associated with increasing BDE-47 concentrations, but a reduced antibody-mediated response that was positively associated with increasing BDE-183 concentrations. There were also structural changes in the spleen (fewer germinal centers), bursa (reduced apoptosis) and thymus (increased macrophages), and negative associations between the spleen somatic index and sigmaPBDEs, and the bursa somatic index and BDE-47. Immunomodulation from PBDE exposure may be exacerbated in wild birds experiencing greater environmental stresses.     

Degradation of trichloroethylene by photocatalysis in an internally circulating slurry bubble column reactor

The effects of initial trichloroethylene (TCE) concentration, recirculating liquid flow rate and gas velocity on photodegradation of TCE have been determined in an internally circulating slurry bubble column reactor (0.15m-ID x 0.85 m-high). Titanium dioxide (TiO2) powder was employed as a photocatalyst and the optimum loading of TiO2 in the present system is found to be approximately 0.2 wt%. The stripping fraction of TCE by air flow increases but photodegradation fraction of TCE decreases with increasing the initial TCE concentration, recirculating liquid flow rate and gas velocity. The average removal efficiency of TCE is found to be approximately 97% in an internally circulating slurry bubble column reactor.     

Control of bacterial growth in water using synthesized inorganic disinfectant

Chlorine is a popular method for controlling bacterial growth in cooling towers. However, there are several drawbacks such as the difficulties in maintaining the disinfection efficacy particularly at high temperature and pH. In order to overcome these difficulties, an inorganic disinfectant based on silver and copper, which is called EEKO-BALL (commercial name), was recently developed. EEKO-BALL is made from specific ceramics and coating materials. This study was performed to evaluate the efficacy of EEKO-BALL and compare it with that of silver (Ag+) and copper (Cu2+) ions. In addition, a field study was undertaken to investigate the control of bacterial growth in several cooling tower systems. The results showed that the contact time required for inactivating 99% of E. coli was 15 min in the EEKO-BALL stock solution at 25 degrees C, pH 7.3, with 0.05 mgl(-1) Ag and 0.05 mgl(-1) Cu. EEKO-BALL was approximately four times more effective than silver and copper ions in inactivating E. coli at 25 degrees C, pH 7.3. The control of bacterial growth in the cooling towers was found to be effective, lasting more than two months after a one-time installation of the EEKO-BALL. Overall, this study suggests that EEKO-BALL can effectively work as an inorganic disinfectant for bacterial growth control.     

Leaching of brominated flame retardants in leachate from landfills in Japan

Leachate samples were taken from seven different landfills and concentrations of brominated flame retardants (BFRs), i.e. polybrominated diphenyl ethers (PBDEs) and tetrabromobisphenol A (TBBPA), were quantified. Leaching characteristics of BFRs, especially factors affecting leachability, were clarified to obtain basic information regarding the release of BFRs into the environment. The results obtained for observed levels of the sum of PBDE-47, -99 and -100 were n.d.--4000 pg/l for the raw leachate and n.d. for the treated one, respectively, and those of TBBPA were n.d.--620,000 pg/l for the raw leachate and n.d.--11,000 pg/l for the treated one, respectively. Three sites that not only had crushed material from bulk wastes such as waste electric and electronic equipment, but also were under operation or within a year since closure, indicated a higher concentration of BFRs than the other sites. In particular extremely high concentration of PBDEs was observed at a site with a large amount of organics. Considering the leaching characteristics of BFRs, there exists the possibility that leachability of PBDEs is influenced by the presence of dissolved humic matter (DHM) in the leachate. The high removal efficiency for BFRs in the leachate treatment process was also confirmed.     

Influence of various reaction parameters on 2,4-D removal in photo/ferrioxalate/H(2)O(2) process

The influence of various reaction parameters on herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) removal were examined in the photo/ferrioxalate/H(2)O(2) system, with regard to: (1) sulfate, phosphate, and z.rad;OH scavenger, as solution constituent; and (2) light intensity, ferrioxalate, H(2)O(2), and oxalate concentration, as operating parameter. In terms of 2,4-D removal, the photo/ferrioxalate/H(2)O(2) system has always been superior to the photo/Ferric ion/H(2)O(2) system, despite the high presence of anions (sulfate 100 mM, phosphate 1 mM) or z.rad;OH scavenger. Not only the rate of 2,4-D removal, but also the decomposition rate of H(2)O(2) and oxalate proportionally increase with light intensity. The ferrioxalate concentration determines the light absorption fraction, and thus, controls the rates of 2,4-D removal, and the decomposition of H(2)O(2) and oxalate, are predicted from kinetic formulations. The optimal concentration of H(2)O(2) and oxalate, according to the extent of the z.rad;OH scavenging reaction with these reagents, has been demonstrated for 2,4-D removal. It was found that an increasing oxalate concentration, which bears the burden of increased dissolved organic carbon (DOC), does not occur. This is because its decomposition, as a result of the photochemical reduction of the ferric oxalate complex, results in a decrease of the equivalent DOC. The importance of the key reaction factors to be considered, when applying this system to real wastewater treatment, is also discussed.     

Contamination by selected chlorinated pesticides in surface waters in Hanoi, Vietnam

Fifteen insecticides, which were banned in Vietnam in the period from 1990 to 1998, were chosen for the investigation of surface water samples in Hanoi and its surroundings. The investigation was focused on an area of approximately 30 by 20 km. Thirty water samples, in total were analysed: 11 samples from the Red river, seven from the Duong river, four from various lakes (West lake, Thuyen Quang, Bay Mau, Ba Mau), six from irrigation canals and two samples from wells. The procedure was repeated in November 1998 and in August 1999. The results showed that the contamination of the banned pesticides was highest in the rivers and then in the irrigation canals, followed by the lakes and wells. These pesticides could hardly be determined in just two drinking water samples (wells) and their concentrations rarely exceeded detection limits (0.05-0.25 ng l(-1)). The mean concentrations of sigmaHCHs (alpha, beta, gamma, delta-HCH) and sigmaDDTs (2,4'-, 4,4'-DDE; 2,4'-, 4,4'-DDD; 2,4'-, 4,4'-DDT) in the rivers were 17.2 +/- 71.8 and 43.7 +/- 79.9 ng l(-1) in the dry season (DS, November 1998), 29.3 +/- 117 and 56.1 +/- 65.6 ng l(-1) in the rainy season (RS, August 1999), respectively. However, the highest concentration of DDTs detected in a river sample (DS): 0.324 microg l(-1) was much lower than their allowable limit of concentration in surface waters, which is accorded with Criteria of Vietnam (1995) (DDTs < 10 microg l(-1)). Moreover, endrin, heptachlor, aldrin were also detected in most of water samples with considerable mean concentrations in rivers: 25.3 +/- 40.5, 17.4 +/- 23.8, 11.0 +/- 9.02 ng l(-1) in the DS and 18.5 +/- 23.2, 19.3 +/- 29.0, 12.8 +/- 8.44 ng l(-1) in the RS, respectively. Heptachlor epoxide (isomer A) and dieldrin were detected in some water samples with lowest concentrations.     

Trichloroethylene degradation by photocatalysis in annular flow and annulus fluidized bed photoreactors

The effects of trichloroethylene (TCE) gas flow rate, relative humidity, TiO(2) film thickness, and UV light intensity on photodegradation of TCE have been determined in an annular flow type photoreactor. Phosgene and dichloroacetyl chloride formation could be controlled as a function of TCE gas flow rate and photodegradation of TCE decreased with increasing relative humidity. The optimum thickness of TiO(2) film was found to be approximately 5 mum and the photocatalytic reaction rate of TCE increased with square root of UV light intensity. In addition, the effects of the initial TCE concentration, phase holdup ratio of gas and solid phases (epsilon(g)/epsilon(s)), CuO loading on the photodegradation of TCE have been determined in an annulus fluidized bed photoreactor. The TCE photodegradation decreased with increasing the initial TCE concentration. The optimum conditions of the phase holdup ratio (epsilon(g)/epsilon(s)) and CuO wt.% for the maximum photodegradation of TCE was found to be 2.1 and 1.1 wt.%, respectively. Therefore, an annulus fluidized bed photoreactor is an effective tool for TCE degradation over TiO(2)/silica gel with efficient utilization of photon energy.     

Catalytic oxidation of pentachlorophenol in contaminated soil suspensions by Fe+3-resin/H2O2

Pentachlorophenol (PCP) is a wood preserving agent that is commonly found in contaminated soils at wood treatment sites. The catalytic properties of Fe+3-resin for the oxidation of PCP in aqueous solution and soil suspension with H2O2 were tested. Batch tests in aqueous solution were performed at various dosages of catalyst and H2O2, and reaction temperatures. The results showed that the oxidation of PCP in aqueous solution depends on the dose of H2O2 and the temperature. Essentially complete oxidation of 100 mgl(-1) PCP was obtained with 0.5% Fe+3-resin catalyst, 0.1 M H2O2 and at a reaction temperature of 80 degrees C. The oxidation of PCP achieved in three different soil suspensions was more than 94% within 30-50 min. Moreover, it was demonstrated that the same Fe+3-resin could be reused for at least six cycles of PCP oxidation in soil solutions without loss in efficiency unless the pH of the reaction falls below 5. It was proposed that the loss in used Fe+3-resin catalyst activity could be related to the leaching of Fe+3 at low pH.     

Mercury and cadmium in common cormorants (Phalacrocorax carbo)

Mercury (Hg) and cadmium (Cd) in common cormorants (Phalacrocorax carbo) collected in Lake Biwa, Japan and Tokyo, Japan, were investigated to elucidate the biological behaviors of these elements, and to assess exposure to these pollutants of wild, fish-eating birds. Hg and Cd concentrations were highest in the liver and kidneys, respectively. The lowest levels of both elements were observed in chicks. Hg concentrations in all tissues except brain increased significantly with growth from chicks to juveniles (p<0.05, U-test). Cd concentrations in the kidneys and liver also increased significantly during growth from juvenile to adult (p<0.005, U-test). When comparing hepatic Hg and Cd in adult birds between 10 samples from Lake Biwa and nine samples from Tokyo, the Cd concentrations in the Lake Biwa samples (1.4+/-0.37 microg/g dry wt) (mean+/-SD) were significantly higher than those from Tokyo (0.32+/-0.16 microg/g dry wt) (p<0.005, U-test), while no statistically significant difference was found in the Hg concentrations. Possible causes of these differences were discussed in relation to their prey.