Paul K S Lam

City University of Hong Kong, Chiu-lung, Kowloon City, Hong Kong

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Publications (325)857.09 Total impact

  • Chuncai Zhou, Guijian Liu, Ting Fang, Dun Wu, Paul Kwan Sing Lam
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    ABSTRACT: A study on toxic elements behaviors from a 330 MW coal gangue circulated fluidized bed co-combustion power plant equipped with electrostatic precipitators (ESPs) was performed. Simultaneous sampling of feed coal, bottom ash, fly ash and flue gas were implemented. Sequential chemical extraction was taken to investigate the transformation behaviors of toxic elements. The relative distribution and partitioning behavior of toxic elements in the power plants were analyzed systemically. The toxic elements can be divided into two groups, Cluster one, whereby high volatile tendencies are represented by As, Cd, Cu, Pb, Se and Sn which have a volatilization ratio more than 20% and are mainly enriched in fly ash. These elements are primarily associated with sulfide minerals. Cluster two, represented by Co, Cr, Mn and V, have low volatilization rate (⩽5%) and are equally distributed between bottom ash and fly ash. In addition, Bi, Ni and Zn may be located between Cluster one and Cluster two. The variation of modes of occurrence of toxic elements could lead to the difference of transformation behaviors during the combustion of feed coal. Most toxic elements transformed and partitioned into other fractions from Fe–Mn oxides during combustion.
    Fuel 11/2014; 135:1–8. · 3.36 Impact Factor
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    ABSTRACT: Organic UV filters are common ingredients of personal care products (PCPs), but little is known about their distribution in and potential impacts to the marine environment. This study reports the occurrence and risk assessment of twelve widely used organic UV filters in surface water collected in eight cities in four countries (China, the United States, Japan, and Thailand) and the North American Arctic. The number of compounds detected, Hong Kong (12), Tokyo (9), Bangkok (9), New York (8), Los Angeles (8), Arctic (6), Shantou (5) and Chaozhou (5), generally increased with population density. Median concentrations of all detectable UV filters were <250 ng/L. The presence of these compounds in the Arctic is likely due to a combination of inadequate wastewater treatment and long-range oceanic transport. Principal component analysis (PCA) and two-way analysis of variance (ANOVA) were conducted to explore spatiotemporal patterns and difference in organic UV filter levels in Hong Kong. In general, spatial patterns varied with sampling month and all compounds showed higher concentrations in the wet season except benzophenone-4 (BP-4). Probabilistic risk assessment showed that 4-methylbenzylidene camphor (4-MBC) posed greater risk to algae, while benzophenone-3 (BP-3) and ethylhexyl methoxycinnamate (EHMC) were more likely to pose a risk to fishes and also posed high risk of bleaching in hard corals in aquatic recreational areas in Hong Kong. This study is the first to report the occurrence of organic UV filters in the Arctic and provides a wider assessment of their potential negative impacts in the marine environment.
    Water research. 09/2014; 67C:55-65.
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    ABSTRACT: Pharmaceuticals have recently been regarded as contaminants of emerging concern. To date, there is limited knowledge about antibiotic-degrading microorganisms in conventional activated sludge treatment systems and their characteristics toward antibiotic degradation especially in the presence of a pharmaceutical mixture. As such, antibiotic-degrading microorganisms were investigated and isolated from the activated sludge, and their degradation capabilities were evaluated. Two strains of cefalexin-degrading bacteria CE21 and CE22 were isolated and identified as Pseudomonas sp. in the collected activated sludge. Strain CE22 was able to degrade over 90% of cefalexin, while CE21 was able to remove 46.7% of cefalexin after incubation for 24h. The removal efficiency of cefalexin by CE22, different from that of CE21, was not significantly affected by an increase in cefalexin concentration, even up to 10ppm, however the presence of 1ppm of other pharmaceuticals had a significant effect on the degradation of cefalexin by CE22, but no significant effect on CE21. The degradation product of cefalexin by the two strains was identified to be 2-hydroxy-3-phenyl pyrazine. Our results also indicated that CE21 and CE22 were able to degrade caffeine, salicylic acid and chloramphenicol. Moreover, CE21 was found to be capable of eliminating sulfamethoxazole and naproxen.
    Journal of hazardous materials. 07/2014;
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    ABSTRACT: The thermal decomposition behavior of coal gangue, peanut shell, wheat straw and their blends during combustion were determined via thermogravimetric analysis. The coal gangue/agricultural biomass blends were prepared in four weight ratios and oxidized under dynamic conditions from room temperature to 1000°C by various heating rates. Kinetic models were carried out to evaluate the thermal reactivity. The overall mass balance was performed to assess the partition behavior of coal gangue, peanut shell and their blends during combustion in a fixed bed reactor. The decomposition processes of agricultural biomass included evaporation, release of volatile matter and combustion as well as char oxidation. The thermal reactivity of coal gangue could be improved through the addition of agricultural biomass in suitable proportion and subsequent appropriate heating rate during combustion. In combination with the heating value and base/acid ratio limitations, a blending ratio of 30% agricultural biomass is conservatively selected as optimum blending.
    Bioresource Technology 05/2014; 166C:243-251. · 5.04 Impact Factor
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    ABSTRACT: Coal mining area is highly subject to lead (Pb) pollution from coal mining activities. Several decades of coal mining and processing practices in dozens of coal mines in the Huainan Coal Mining Area (HCMA) have led to the accumulation of massive amounts of coal gangue, which piled in dumps. In order to investigate the impacts of coal gangue dumps on Pb level in the supergene media of the HCMA, a systematic sampling campaign comprising coal gangue, soil, wheat, and earthworm samples was conducted. The average Pb content in the coal mining area soil is 24 mg/kg, which is slightly higher than the associated coal gangues (23 mg/kg) and markedly higher than reference region soil (12.6 mg/kg). Soil in the HCMA present a slight to moderate Pb contamination, which might be related to the weathering and leaching of coal gangue dumps. Lateral distribution of Pb in HCMA soil differed among individual coal mines. The soil profile distribution of Pb depends on both natural and anthropogenic contributions. Average Pb content is higher in roots than in stems, leaves, and wheat husks, while the Pb level in seeds exceeded the maximum Pb allowance for foods (Maximum Levels of Contaminants in Foods of China, GB 2762-2012). Earthworms in the selected area are significantly enriched in Pb, suggesting higher bio-available Pb level in soil in the HCMA.
    Environmental Monitoring and Assessment 04/2014; · 1.68 Impact Factor
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    ABSTRACT: The present study investigated the composition profiles and levels of polybrominated diphenyl ethers (PBDEs) and five PBDE alternatives in the blubber of two species of marine mammals, Indo-Pacific humpback dolphins (Sousa chinensis) and finless porpoises (Neophocaena phocaenoides) from the South China Sea. Despite the fact that PBDEs were the most predominant brominated flame retardants in the samples analyzed, decabromodiphenyl ethane (DBDPE), 1,2-bis (2,4,6-tribromophenoxy) ethane (BTBPE), bis- (2-ethylhexyl) -tetrabromophthalate (TBPH), 2-ethylhexyl 2,3,4,5-tetrabromobenzoate (TBB) and Dechlorane Plus (DP) were all detected in both cetacean species. In addition, significantly increasing temporal shifting trends of Deca-BDE to DBDPE, Octa-BDE to BTBPE, and Deca-BDE to DP were observed in porpoise samples between 2003 and 2012 and dolphin samples between 2003 and 2011. These patterns may be attributed to the replacement of PBDEs by alternative halogenated flame retardants (HFRs) and the increasing usage of these alternatives following the restriction/voluntary withdrawal of the production and use of PBDE commercial mixtures. Our findings suggest that the study region may be a source of contamination by PBDE alternative flame retardants due to the high detection frequencies and levels of these compounds in marine mammals.
    Environment international 02/2014; 66C:65-70. · 6.25 Impact Factor
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    ABSTRACT: Organic ultraviolet (UV) filters are applied widely in personal care products (PCPs), but the distribution and risks of these compounds in the marine environment are not well known. In this study, the occurrence and removal efficiencies of 12 organic UV filters in five wastewater treatment plants (WWTPs) equipped with different treatment levels in Hong Kong, South China, were investigated during one year and a preliminary environmental risk assessment was carried out. Using a newly developed simultaneous multiclass quantification liquid chromatography-tandem mass spectrometry (LC-MS/MS) method, butyl methoxydibenzoylmethane (BMDM), 2,4-dihydroxybenzophenone (BP-1), benzophenone-3 (BP-3), benzophenone-4 (BP-4) and 2-ethyl-hexyl-4-trimethoxycinnamate (EHMC) were frequently (≥80%) detected in both influent and effluent with mean concentrations ranging from 23 to 1290 ng/L and 18-1018 ng/L, respectively; less than 2% of samples contained levels greater than 1000 ng/L. Higher concentrations of these frequently detected compounds were found during the wet/summer season, except for BP-4, which was the most abundant compound detected in all samples in terms of total mass. The target compounds behaved differently depending on the treatment level in WWTPs; overall, removal efficiencies were greater after secondary treatment when compared to primary treatment with >55% and <20% of compounds showing high removal (defined as >70% removal), respectively. Reverse osmosis was found to effectively eliminate UV filters from effluent (>99% removal). A preliminary risk assessment indicated that BP-3 and EHMC discharged from WWTPs may pose high risk to fishes in the local environment.
    Water Research 01/2014; 53C:58-67. · 4.66 Impact Factor
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    ABSTRACT: The thermal decomposition behavior of coal gangue, peanut shell, wheat straw and their blends during combustion were determined via thermogravimetric analysis. The coal gangue/agricultural biomass blends were prepared in four weight ratios and oxidized under dynamic conditions from room temperature to 1000 °C by various heating rates. Kinetic models were carried out to evaluate the thermal reactivity. The overall mass balance was performed to assess the partition behavior of coal gangue, peanut shell and their blends during combustion in a fixed bed reactor. The decomposition processes of agricultural biomass included evaporation, release of volatile matter and combustion as well as char oxidation. The thermal reactivity of coal gangue could be improved through the addition of agricultural biomass in suitable proportion and subsequent appropriate heating rate during combustion. In combination with the heating value and base/acid ratio limitations, a blending ratio of 30% agricultural biomass is conservatively selected as optimum blending.
    Bioresource Technology 01/2014; 166:243–251. · 5.04 Impact Factor
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    ABSTRACT: An investigation focused on the transformation and distribution behaviors of trace elements and natural radionuclides around a coal gangue brick plant was conducted. Simultaneous sampling of coal gangue, brick, fly ash and flue gas were implemented. Soil, soybean and earthworm samples around the brick plant were also collected for comprehensive ecological assessment. During the firing process, trace elements were released and redistributed in the brick, fly ash and the flue gas. Elements can be divided into two groups according to their releasing characteristics, high volatile elements (release ratio higher than 30%) are represented by Cd, Cu, Hg, Pb, Se and Sn, which emitted mainly in flue gas that would travel and deposit at the northeast and southwest direction around the brick plant. Cadmium, Ni and Pb are bio-accumulated in the soybean grown on the study area, which indicates potential health impacts in case of human consumption. The high activity of natural radionuclides in the atmosphere around the plant as well as in the made-up bricks will increase the health risk of respiratory system.
    Scientific reports. 01/2014; 4:6221.
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    ABSTRACT: The measurement of illicit drug metabolites in raw wastewater is increasingly being adopted as an approach to objectively monitor population-level drug use, and is an effective complement to traditional epidemiological methods. As such, it has been widely applied in western countries. In this study, we utilised this approach to assess drug use patterns over nine days during April 2011 in Hong Kong. Raw wastewater samples were collected from the largest wastewater treatment plant serving a community of approximately 3.5 million people and analysed for excreted drug residues including cocaine, ketamine, methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA) and key metabolites using liquid chromatography coupled with tandem mass spectrometry. The overall drug use pattern determined by wastewater analysis was consistent with that have seen amongst people coming into contact with services in relation to substance use; among our target drugs, ketamine (estimated consumption: 1400-1600mg/day/1000 people) was the predominant drug followed by methamphetamine (180-200mg/day/1000 people), cocaine (160-180mg/day/1000 people) and MDMA (not detected). The levels of these drugs were relatively steady throughout the monitoring period. Analysing samples at higher temporal resolution provided data on diurnal variations of drug residue loads. Elevated ratios of cocaine to benzoylecgonine were identified unexpectedly in three samples during the evening and night, providing evidence for potential dumping events of cocaine. This study provides the first application of wastewater analysis to quantitatively evaluate daily drug use in an Asian metropolitan community. Our data reinforces the benefit of wastewater monitoring to health and law enforcement authorities for strategic planning and evaluation of drug intervention strategies.
    Forensic science international 12/2013; 233(1-3):126-32. · 2.10 Impact Factor
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    ABSTRACT: Saxitoxin (STX) is the most potent paralytic shellfish poisoning toxin in crustaceans and molluscs, and is known to cause intoxication to humans and marine animals due to its neurotoxicity. However, the extent of its early developmental toxicity to marine species remains unknown. In this study, we examined the early developmental toxicity of STX using marine medaka (Oryzias melastigma) embryos as model. The medaka embryos were exposed to STX for four days, from the early blastula stage onwards, and this exposure period covered the main developmental stage of the central nervous system and somites. After exposure, the treated medaka eleutheroembryos at 15 day post fertilization exhibited abnormal growth with longer body length and relatively smaller yolk sac size. High cell proliferation, neuron development, and metabolism were confirmed using whole-mount immunostaining and two-dimensional electrophoresis. In summary, STX disturbed the normal growth of medaka embryos probably by affecting the metabolic rate in the exposed medaka embryos.
    Toxicon 10/2013; · 2.92 Impact Factor
  • Chuncai Zhou, Guijian Liu, Shengchun Wu, Paul Kwan Sing Lam
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    ABSTRACT: The behaviors of natural radionuclides and toxic elements during coal gangue brick making processes are described. A simulation experiment of coal gangue brick firing was carried out to evaluate the enrichments of natural radionuclides and volatilizations of elements. Simultaneous sampling of coal gangue and corresponding combustion product (slag) was performed. The radioactivities of the radionuclide were determined by high-purity germanium gamma ray spectrometer, and the concentrations of toxic elements were analyzed by ICP-MS. Results have shown that the level of natural radionuclides may not cause immediate or acute environmental impacts because the Raeq values and Hex (in the brick) are 345Bqkg(-1) and 0.89, lower than the limit values of 370Bqkg(-1) and 1, respectively. However, the Raeq and Hex values are near the limit values, their chronic-environmental and health impacts should be considered noteworthy. The elements found in the emission could be categorized into two types: non-volatilized elements (Co, Cr, Mn and V) and volatilized elements (As, Cd, Cu, Ni, Se, Sn and Zn). Understanding the behaviors of natural radionuclides and toxic elements during brick making processes is helpful for the assessment of their potential impacts to human health and the environment.
    Chemosphere 10/2013; · 3.14 Impact Factor
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Publication Stats

6k Citations
857.09 Total Impact Points

Institutions

  • 1996–2014
    • City University of Hong Kong
      • • State Key Laboratory in Marine Pollution
      • • Department of Biology and Chemistry
      Chiu-lung, Kowloon City, Hong Kong
  • 2010–2013
    • University of Science and Technology of China
      • School of Earth and Space Sciences
      Hefei, Anhui Sheng, China
  • 2008–2013
    • Chinese Academy of Sciences
      • Key Laboratory of Animal Ecology and Conservation Biology
      Peping, Beijing, China
  • 2006–2013
    • National Institute of Advanced Industrial Science and Technology
      Tsukuba, Ibaraki, Japan
    • National Water Research Institute
      Fountain Valley, California, United States
    • University of Gdansk
      Danzig, Pomeranian Voivodeship, Poland
    • The Hong Kong Polytechnic University
      • Department of Civil and Environmental Engineering
      Hong Kong, Hong Kong
    • Indonesian Institute of Sciences
      Batavia, Jakarta Raya, Indonesia
  • 2012
    • Kumamoto University
      • Graduate School of Science and Technology
      Kumamoto-shi, Kumamoto Prefecture, Japan
  • 2006–2012
    • Northeast Institute of Geography and Agroecology
      • Institute of Hydrobiology
      Beijing, Beijing Shi, China
  • 1985–2012
    • The University of Hong Kong
      • Department of Biochemistry
      Hong Kong, Hong Kong
  • 2011
    • USTC-CityU Joint Advanced Research Center
      Hong Kong, Hong Kong
    • Helmholtz-Zentrum für Umweltforschung
      • Department Analytische Umweltchemie
      Leipzig, Saxony, Germany
  • 2008–2009
    • The Hong Kong University of Science and Technology
      Chiu-lung, Kowloon City, Hong Kong
  • 2006–2009
    • National Institute of Animal Health
      Tsukuba, Ibaraki, Japan
  • 1990–2009
    • The Chinese University of Hong Kong
      • Department of Biology
      Hong Kong, Hong Kong
  • 2005–2008
    • Michigan State University
      • Department of Zoology
      East Lansing, MI, United States
  • 2003–2008
    • Ehime University
      • Center for Marine Environmental Studies (CMES)
      Matsuyama-shi, Ehime, Japan
  • 2007
    • Woods Hole Oceanographic Institution
      • Department of Biology
      Falmouth, MA, United States
  • 2002–2007
    • University of Queensland 
      • National Research Centre for Environmental Toxicology
      Brisbane, Queensland, Australia