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Volume 1, Number 1, March 2012
Abstract
We demonstrated that reductive degradation of 2,4,6-Trinitrotoluene (TNT) and hexahydro- 1,3,5-trinitro-1,3,5-triazine (Royal Demolition Explosive, RDX) can be enhanced by bio-reduced ironbearing soil minerals (IBSMs) using Shewanella putrefaciens CN32 (CN32). The degradation kinetic rate constant of TNT by bio-reduced magnetite was the highest (0.0039 h-1), followed by green rust (0.0022 h-1), goethite (0.0017 h-1), lepidocrocite (0.0016 h-1), and hematite (0.0006 h-1). The highest rate constant was obtained by bio-reduced lepidocrocite (0.1811 h-1) during RDX degradation, followed by magnetite (0.1700 h-1), green rust (0.0757 h-1), hematite (0.0495 h-1), and goethite (0.0394 h-1). Significant increase of Fe(II) was observed during the reductive degradation of TNT and RDX by bio-reduced IBSMs. X-ray diffraction and electron microscope analyses were conducted for identification of degradation mechanism of TNT and RDX in this study. 4-amino-dinitrotoluene were detected as products during TNT degradation, while Hexahydro-1- nitroso-3,5-dinitro-1,3,5-triazine, Hexahydro-1,3-dinitroso-5-nitro-1,3,5triazine, and Hexahydro-1,3,5- trinitroso-1,3,5-triazine were observed during RDX degradation.
Key Words
2,4,6-Trinitrotoluene (TNT); hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX); iron-bearing soil minerals; Shewanella putrefaciens CN32
Address
Changhyun Cho, Sungjun Bae and Woojin Lee: Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea
Abstract
Mercury (Hg) is a global environmental pollutant that has been the cause of many public concerns. One particular concern about Hg in aquatic systems is its trophic transfer and biomagnification in food chains. For example, the Hg concentration increases with the increase of food chain level. Fish at the top of food chain can accumulate high concentrations of Hg (especially the toxic form, methylmercury, MeHg), which is then transferred to humans through seafood consumption. Various biological and hysiochemical conditions can significantly affect the bioaccumulation of Hg−including both its inorganic (Hg(II)) and organic (MeHg) forms−in fish. There have been numerous measurements of Hg concentrations in marine and freshwater fish worldwide. Many of these studies have attempted to identify the processes leading to variations of Hg concentrations in fish species from different habitats. The development of a biokinetic model over the past decade has helped improve our understanding of the mechanisms underlying the bioaccumulation processes of Hg in aquatic animals. In this review, I will discuss how the biokinetic modeling approach can be used to reveal the interesting biodynamics of Hg in fish, such as the trophic transfer and exposure route of Hg(II) and MeHg, as well as growth enrichment (the increases in Hg concentration with fish size) and biomass dilution (the decreases in Hg concentration with increasing phytoplankton biomass). I will also discuss the relevance of studying the subcellular fates of Hg to predict the Hg bioaccessibility and detoxification in fish. Future challenges will be to understand the inter- and intra-species differences in Hg accumulation and the management/mitigation of Hg pollution in both marine and freshwater fish based on our knowledge of Hg biodynamics.
Key Words
mercury; fish; biodynamics; bioaccumulation; biodilution; subcellular distribution; risk assessment
Address
Wen-Xiong Wang: Division of Life Science, The Hong Kong University of Science and Technology (HKUST), Clearwater Bay, Kowloon, Hong Kong
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Reduction of perchlorate using zero-valent titanium (ZVT) anode: reaction mechanism
Chunwoo Lee, Bill Batchelor, Sung Hyuk Park, Dong Suk Han, Ahmed Abdel-Wahab and Timothy A. Kramer
Abstract;
Full Text (3289K)
Abstract
Here we show that perchlorate reduction during pitting corrosion of zero-valent titanium (ZVT) is likely caused by dissolved titanium species, especially Ti(II). Several possible mechanisms were suggested based on the literature and were evaluated based on experimental observations. Direct reduction of perchlorate on the bare metal of the ZVT electrode was thermodynamically infeasible due to the highanodic potential that was applied. Other potential mechanisms were considered such as reduction by small ZVT metal particles released from the electrode and direct reduction on the oxide layer of the electrode where potential was sufficiently reduced by a high anodic potential drop. However, these mechanisms were not supported by experimental results. The most likely mechanism for perchlorate reduction was that during pitting corrosion, in which ZVT is partially oxidized to form dissolved ions such as Ti(II), which diffuse from the electrode surface and react with perchlorate in solution. This mechanism is supported by measurements of the dissolution valence and the molar ratio of ZVT consumed to perchlorate reduced (ΔTi(0)/ΔClO4-). The results shown in this study demonstrate that ZVT undergoing pitting corrosion has the capability to chemically reduce perchlorate by producing dissolved Ti(II) and therefore, it has the potential to be applied in treatment systems. On the other hand, the results of this research imply that the application of ZVT undergoing pitting corrosion in treatment systems may not be feasible now due to several factors, including material and electricity costs and possible chloride oxidation.
Key Words
perchlorate; reduction; corrosion; zero-valent titanium; reductant
Address
Chunwoo Lee: Doosan Hydro Technology, Inc., Tampa, FL 33619, USA; Bill Batchelor: Zachry Department of Civil Engineering, Texas A&M University, College Station, TX 77840, USA; Sung Hyuk Park: Environmental & Energy Research Team, GS Engineering & Construction Research Institute, Youngin-si, Kyunggi-do, 449-831, Republic of Korea; Dong Suk Han and Ahmed Abdel-Wahab: Chemical Engineering Program, Texas A&M University at Qatar, Education City, Doha, PO Box 23874, Qatar; Timothy A. Kramer: Deceased
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Air pollution and hospital admissions for chronic obstructive pulmonary disease: are their potentially sensitive groups?
Shang-Shyue Tsai, Ya-Hui Yang, Saou-Hsing Liou,
Trong-Neng Wu and Chun-Yuh Yang
Abstract;
Full Text (263K)
Abstract
Recent studies showed that air pollution is a risk factor for hospitalization for chronic obstructive pulmonary disease (COPD). However, there is limited evidence to suggest which subpopulations are at higher risk from air pollution. This study was undertaken to examine the modifying effect of specific secondary diagnosis (including hypertension, diabetes, pneumonia, congestive heart failure) on the relationship between hospital admissions for COPD and ambient air pollutants concentrations. Hospital admissions for COPD and ambient air pollution data for Taipei were obtained for the period from 1999-2009. The relative risk of hospital admissions for COPD was estimated using a case-crossover approach. None of the secondary diagnosis we examined showed much evidence of effect modification.
Key Words
air pollution; COPD; sensitive population; case-crossover; hospital admissions
Address
Shang-Shyue Tsai: Department of Healthcare Administration, I-Shou University, Kaohsiung, Taiwan; Ya-Hui Yang: Department of Occupational Safety and Hygiene, Fooyin University, Kaohsiung, Taiwan; Saou-Hsing Liou: Division of Environmental Health and Occupational Medicine, National Health Research Institute, Miaoli, Taiwan; Trong-Neng Wu: Graduate Institute of Public Health, China Medical University, Taichung, Taiwan; Trong-Neng Wu and Chun-Yuh Yang: Division of Environmental Health and Occupational Medicine, National Health Research Institute, Miaoli, Taiwan; Chun-Yuh Yang: Department of Public Health, College of Health Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan
Abstract
Based on the measurement data of the particulate matter with an aerodynamic diameter of less than or equal to a nominal 10 µm (PM10) by the β-ray absorption method (BAM) equipped with an inlet heater and the gravimetric method (GMM) at two coastal sites in Korea, the optimal inlet heater temperature was estimated. By using a gas/particle equilibrium model, Simulating Composition of Atmospheric Particles at Equilibrium 2 (SCAPE2), water content in aerosols was estimated with varying temperature to find the optimal temperature increase to make the PM10 concentration by BAM comparable to that by GMM. It was estimated that the heated air temperature inside the BAM should be increased up to 35~45°C at both sites. At this temperature range, evaporation of volatile aerosol components was minor. Similar (30~50°C) temperature range was also obtained from the calculation based on the absolute humidity which changed with ambient absolute humidity and chemical composition of hygroscopic species.
Key Words
PM10; β-ray absorption method; gravimetric method; water content; gas-particle equilibrium; optimal inlet air temperature increase
Address
So Eun Shin and Yong Pyo Kim: Department of Environmental Science and Engineering, Ewha Womans University, Seoul, Korea; Chang Hoon Jung: Department of Health Care Management, Kyung In Women\'s College, Inchon, Korea
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Incorporation of water sludge, silica fume, and rice husk ash in brick making
Badr El-Din Ezzat Hegazy, Hanan Ahmed Fouad and Ahmed Mohammed Hassanain
Abstract;
Full Text (1510K)
Abstract
The water sludge is generated from the treatment of water with alum. Disposing of sludge again to the streams raises the concentrations of aluminum oxides in water, which has been linked to Alzheimer's disease. The use of water treatment plant (WTP) sludge in manufacturing of constructional elements achieves both the economical and environmental benefits. Due to the similar mineralogical composition of clay and WTP sludge, this study investigated the complete substitution of brick clay by sludge incorporated with some of the agricultural and industrial wastes, such as rice husk ash (RHA) and silica fume (SF). Three different series of sludge to SF to RHA proportions by weight were tried, which were (25: 50: 25%), (50: 25: 25%), and (25: 25: 50%), respectively. Each brick series was fired at 900, 1000, 1100, and 1200oC. The physical and mechanical properties of the produced bricks were then determined and evaluated according to Egyptian Standard Specifications (E.S.S.) and compared to control clay-brick. From the obtained results, it was concluded that by operating at the temperature commonly practiced in the brick kiln, a mixture consists of 50% of sludge, 25% of SF, and 25% of RHA was the optimum materials proportions to produce brick from water sludge incorporated with SF and RHA. The produced bricks properties were obviously superior to the 100% clay control-brick and to those available in the Egyptian market.
Key Words
water treatment sludge; sludge disposal; clay; brick; silica fume; rice husk ash
Address
Badr El-Din Ezzat Hegazy, Hanan Ahmed Fouad and Ahmed Mohammed Hassanain: Department of Civil Engineering, Faculty of Engineering at Shoubra, Benha University, Cairo, Egypt
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Editor-in-Chief
