DSpace Collection: http://dspace.cityu.edu.hk:80/handle/2031/728 Tue, 21 Oct 2014 00:42:58 GMT 2014-10-21T00:42:58Z Changes of eco-environment in the Xisha Islands in response to climate change and human activity over the past 2000 years http://dspace.cityu.edu.hk:80/handle/2031/7208 Title: Changes of eco-environment in the Xisha Islands in response to climate change and human activity over the past 2000 years Authors: Xu, Liqiang (徐利強) Abstract: ﻿Global warming significantly impacts on ecosystems and has drawn increasing attention in recent years. However, how climate changes affect lives and the environment remains unclear. The past is the key to the future, and study of the past is essential for predicting the future. Seabirds move across aquatic/terrestrial ecosystem boundaries and their fossil remains have been widely used for studying ecological responses to climate change. Five sediment cores from Ganquan (GQ), Guangjin (GJ3), Jinqing (JQ), Jinyin (JY2) and Chenhang (CH) islands of the Xisha archipelago, South China Sea, were collected during field investigations. Well-preserved seabird remains were observed in these sediment cores. Via elemental, isotopic and biological geochemistry analyses, the history of the islands has been examined and major points of the present study are summarized as follows. 1. Establishment of chronologies for the five sediment cores Via analysis of several natural and anthropogenic radionuclides (210Pb, 226Ra and 137Cs) in the ornithogenic sediments, 210Pb dating has been proven to be effective for coral sand sediments in the Xisha Islands. The Constant Initial Concentration (CIC) model and the Constant Rate of Supply (CRS) model were applied for age calculation. The average supply rate of 210Pb was 126 Bq m-2 a-1, very close to the flux of northern hemisphere average (125 Bq m-2 a-1). The main source of radionuclides in the sediments is atmospheric precipitation, and the organic matter derived from plant and produced by nutrient-rich guano could further enhance them. Chronologies of the five sediments cores were further established by both 210Pb dating and radiocarbon analysis of ancient bones. Age models showed that the most ancient sample of these cores dated back to approximately 2000 years. 2. Geochemical characteristics of the bulk sediments and implications Geochemical characteristics of four profiles GQ, GJ3, JQ and JY2 were analyzed. We noted clear differences in the distribution of organic matter (OM) and elements above and below the respective critical depths of 11 cm (GQ), 16 cm (GJ3), 9 cm (JQ) and 12 cm (JY2) in the four profiles, revealing an apparent change in sediment source materials. Our results suggest that the source materials of ornithogenic sediments have changed gradually from a two-component (coral sand, guano) mixture to a three-component (coral sand, guano and humus) mixture, likely indicating the slow development of vegetation following seabird occupation. Cu, Cd, Zn, P, As, Se and Ba were identified as a group of avian bio-elements. Seabird activities appear central to terrestrial production and soil development on the islands. 3. Seabird population records over the past 2000 years and possible causes for seabird population changes Using avian-bioelements and reflectance spectroscopy, seabird population records of the islands over the past 2000 years were reconstructed. The results show that seabird occupation history of these tropical islets follows a rather similar pattern. Seabird populations peaked during the Little Ice Age (LIA, 1400-1850 AD). A cool climate during the LIA seems more favorable to seabirds on the Xisha Islands of the South China Sea. Relative low sea surface temperature (SST), stronger monsoons and weaker ENSO activity during the LIA might result in increase in marine nutrient mixing and high primary productivity. This provided high food availability and thus supported more seabirds. Moreover, a change in nitrogen/carbon isotope compositions in the collagen of seabird bones suggested that seabirds might dive deeper or travel further to catch prey, due to intra/inter-competitions. The abrupt decline of seabird population in recent times is probably attributed to human activity. 4. Cadmium in guano as an indicator of historical maritime productivity, and reconstruction of marine productivity over the last millennium Cadmium in ancient guano particles was analyzed, and has been identified as an indicator of maritime productivity in the open sea around the Xisha archipelago. The reconstructed maritime production record suggests that the Xisha area had a relatively high productivity and supported more seabirds during the LIA. The East Asian winter monsoon plays a principal role in biomass production in the South China Sea. The intensified winter monsoon during the LIA promoted deep seawater mixing and thus enhanced nutrient cycling. Terrestrial dust along with the cold/dry winter monsoon from Asian continent to the South China Sea may also have promoted maritime productivity. Solar irradiation variability is perhaps the ultimate controlling factor in seabird population on the atolls on the centennial to millennial scales. 5. Evidence of past human activity The level of Hg in eggshells of GJ3 was examined, and was identified as a marker for past Hg deposition in marine environment. Deposition flux of anthropogenic Hg over the past 700 years was also reconstructed from bulk sediments of GJ3, JY2 and JQ. Eggshell Hg and Hg flux well recorded past human activity, including enhanced metallurgy activity in Ming Dynasty of China, exploitation on the Europe/America and World War II. Our records suggest that Hg production center had gradually shifted from Europe and America to Asia since 1970s. We reconstructed a 400-year record of black carbon (BC) deposition flux from profiles GJ3, JQ and JY2. The BC flux remained low before the onset of 20th century; it started to increase from approximately 1900 AD, and peaked around the 1970s. In the recent 30 years, the BC flux displayed decreasing trend, very likely due to a change of energy structure and development of pollution control techniques. 6. DNA isolation from ancient guano samples Preliminary analysis of DNA in ancient bird droppings suggests that the guano contains quite a low level of ancient DNA, due to possible severe degradation. Notes: CityU Call Number: QC903.2.C6 X8 2012; xii, 194 leaves : ill. 30 cm.; Thesis (Ph.D.)--City University of Hong Kong, 2012.; Includes bibliographical references. Sun, 01 Jan 2012 00:00:00 GMT http://dspace.cityu.edu.hk:80/handle/2031/7208 2012-01-01T00:00:00Z Preparation, assembly and surface wettability of hierarchical structured composite microspheres http://dspace.cityu.edu.hk:80/handle/2031/7207 Title: Preparation, assembly and surface wettability of hierarchical structured composite microspheres Authors: Xu, Dezhi (徐德智) Abstract: ﻿The development of polymer microspheres has great influence on our economy and life. It has become an increasingly important subject to achieve desirable physical properties for coatings, light-sensing materials, bio-medicine, and so on. Furthermore, the morphology and size of particles are key factors to determine potential applications of polymer microspheres. So that, great interest has been focused on the morphology control of polymer microspheres, and the microspheres with different novel morphologies have been prepared. Amongst, the hierachical microspheres have attracted more and more attention because of their wide range of applications, e.g. surface enhanced Raman scattering (SERS), heterogeneous catalysts, and most importantly, fabrication of superhydrophobic materials. As we know, the raspberry hybrid particle possesses well-defined hierarchical structure, which consists of a microsized core decorated with nanoscaled particles on the surface. Thus, nowadays, raspberry hybrid particles have been intensively employed by more and more researchers to prepare superhydrophobic films with a dual-size hierarchical structured surface. This study aims at the preparation of raspberry, core-shell and triangle particles with controllable morphologies by different emulsion system (seed emulsion, miniemulsion) based on the interface physical chemistry theory, and the assembly of these particles to fabricate particulate surface with particular wettability. The main content is as follows: 1. raspberry-like SiO2/PS particles were prepared by introducing of MPS-modified SiO2 particles into radiation miniemulsion polymerization of St. MPS modification with a lower cover density of 0.90 molecules/nm2 on the surface of SiO2 is a crucial step to form a raspberry-like structure. The WSt/o-SiO2 (weight ratio of St to o-SiO2) and surfactant concentration also influence the morphology and wettability of the resultant SiO2/PS hybrid particles. The optimum WSt/o-SiO2 and SDS concentration for well-defined raspberry SiO2/PS particles is 50 and 6.94 mM, respectively. When the raspberry SiO2/PS particles were deposited on a glass substrate from ethanol dispersion, a film with dual-size roughness on the surface can be obtained. The surface of the film exhibites superhydrophobic property with a water contact angle of 151o and a large contact angle hysteresis (~116°). Compared with the traditional superhydrophobic surface, the as-prepared layer shows strong adhesion to water. The mechanism of the superhydrophobilicity and high adhesion to water produced on the raspberry SiO2/PS particulate film was considered to be the Gecko’s state because of the van der Waals force between water and PS nanospheres on the film surface and the large density of the PS nanoparticles contacted with water (~1.55×107/mm2). This kind of superhydrophobic particulate film can be used as a “mechanical hand” for transportation of small water droplets without lost, thus it may have potential applications in industrial field. 2. Submicron-sized polystyrene/polyacrylonitrile (PS/PAN) hybrid particles were prepared by γ-ray-induced seeded polymerization, in which the mono-disperse poly (acrylic acid) (PAA)-functionalized PS particles were used as seed particles and acrylonitrile (AN) as the second monomer. The morphology of the PS/PAN hybrid particles could be easily controlled by the pH value of seeded emulsion system. In particular, with the increase of pH value from 4 to 9.6, the morphology of the corresponding PS/PAN hybrid particles gradually changed from core-shell to well-defined raspberry-like structure. The result of X-ray photoelectron spectroscopy (XPS) spectrum revealed the existence of PAN on the surface of the resultant hybrid particles. In addition, the particulate films were constructed by assembling these raspberry-like particles on glass substrates. Without any treatment, superhydrophilic surfaces can be obtained and the contact angle of water on the dual-sized structured surface is highly influenced by the micro/nano surface structure of raspberry-like particles. 3. It is well know that silica must be modified with silane coupling agent, such as MPS, to improve the affinity of SiO2 particles to organic components before they can be used as carrier to load polymer. However, recently, we have successfully prepared raspberry silica/polyacrylonitrile (SiO2/PAN) hybrid particles by γ-ray radiation induced seeded polymerization using unmodified SiO2 particles (590 nm) as seeds. The surface morphologies of the obtained SiO2/PAN can be easily adjusted by the weight ratio of AN to SiO2 seeds. Most importantly, superhydrophilic surfaces can be obtained by assembling these raspberry-like SiO2/PAN particles on glass substrates, and the contact angle of water on the dual-sized structured surface is greatly influenced by the micro/nano surface structure of raspberry-like particles. 4. PS/silica hybrid microspheres with core-shell and raspberry-like structure were prepared respectively with different sol-gel reaction catalysts (NH3·H2O, diethanolamine ， triethylolamine and triethylamine) in the presence of PS microspheres. The PS microspheres were prepared by dispersion polymerization using poly(vinylpyrrolidone) (PVP) as the stabilizer. Since the seed PS microspheres contain PVP molecules on the surface, which was facilitated to give perfect location of silica on PS microspheres. After calcination of the core/shell structured particles at 800 °C, hollow silica microspheres were successfully prepared. The formation of hollow silica particles strongly indicates that PVP-stabilized PS microspheres prepared by dispersion polymerization can be successfully employed to the fabrication of a well-defined silica layer due to the existence of PVP molecules on the surface. The wettability of the PS and PS/SiO2 microspheres was also characterized by measuring the water contact angle of the corresponding particulate film. Furthermore, a novel strategy has been designed for the preparation of triangle polystyrene/SiO2 (PS/SiO2) hybrid particles using radiation-induced seeded emulsion polymerization from above PS/SiO2 seed particles. The triangle particles can be fabricated in relatively high yield when the weight ratio of monomer/seed particles (WSt/PS) is 5. Moreover, the size of the protruded PS bulbs of the triangle particles obviously increases with the weight ratio of monomer/seed particles from 1.25 to 5. This novel method is applicable to the preparation of anisotropic hybrid particles from polymer/inorganic core-shell particles. 5. Polystyrene (PS) microspheres with hydrophilic β-cyclodextrin (β-CD) shell were fabricated one-step via γ-ray radiation induced emulsion polymerization in a simple ternary system of styrene/β-CD/water (St/β-CD/water) at room temperature. The solid inclusion complex of St and β-CD (St/β-CD IC) particles formed at the St droplets-water interface act in-situ as the surfactant not only to stabilize the emulsion but also make contribution to the formation of a hydrophilic β-CD shell on the prepared PS microspheres, which was observed by TEM and XPS investigation. The average size of the PS particles is dependent on the weight ratio of β-CD to St (Wβ-CD/St), which increases from 186 nm to 294 nm as Wβ-CD/St rises from 5% to 12.5%. The water contact angle (CA) of the obtained PS latex film was measured to study the hydrophilic property of PS microspheres. The results show that all the CA of the obtained PS latex film are lower than 90o, and reduce with the content of β-CD even to 36o. Thus, this work provides a new and one-pot strategy to surface hydrophilic modification on hydrophobic polymer particles with cyclodextrins through radiation emulsion polymerization. Notes: CityU Call Number: TA418.9.N35 X78 2012; xxxii, 201 leaves : ill. 30 cm.; Thesis (Ph.D.)--City University of Hong Kong, 2012.; Includes bibliographical references. Sun, 01 Jan 2012 00:00:00 GMT http://dspace.cityu.edu.hk:80/handle/2031/7207 2012-01-01T00:00:00Z Organic geochemistry and photodegradation of organic pollutants in the environment http://dspace.cityu.edu.hk:80/handle/2031/7203 Title: Organic geochemistry and photodegradation of organic pollutants in the environment Authors: Wang, Ruwei (王儒威) Abstract: ﻿Polycyclic aromatic hydrocarbons (PAHs) belong to a class of organic contaminants of great environmental concern. They have grasped much attention due to their carcinogenic potential and ubiquitous presence in the environment. The main pathway for PAHs to enter human bodies is via breathing polluted air or through the food chain. Various forms of PAHs in coals or from coal combustion may affect human, especially indoor coal combustion. In the meantime, PAHs in raw coal can reduce or even poison the activity of catalysts in the refinery, making the stockpile of liquid product unstable. Many literatures concluded that most of the PAHs come from fossil-fuel combustion. However, their pollution from raw coal were usually neglected. The movement and distribution of PAHs in the environment depends on properties such as how easily they dissolve in water, and how easily they evaporate into the air. The abundances of sixteen polycyclic aromatic hydrocarbons (PAHs) on the priority list of U.S. Environmental Protection Agency (USEPA) have been determined in fourteen Chinese and American coals. The ranks of the samples range from lignite, bituminous coal, anthracite to natural coke. Soxhlet extraction was conducted on each coal for 48 h. The extract was analyzed on gas chromatograph-mass spectrometer (GC-MS). The results show that the total PAHs content ranged from 0.31 μg/g to 57.6 μg/g coal (on a dry basis). It varied with coal rank and is highest in the maturity range of bituminous coal rank. High-molecular-weight (HMW) PAHs are predominant in low-rank coals, but low-molecular-weight (LMW) PAHs are predominant in high-rank coals. The Low-sulfur coals have a higher PAHs content than high S coals. It may be explained by an increasing connection between disulfide bonds and PAHs in high-S coal. In addition, it leads us to conclude that the PAH content of coals may be related to the depositional environment. Fly ash and bottom ash samples were collected from a coal-fired power plant located in Anhui province, China. Mineral phases and morphologies of the samples were determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. 16 polycyclic aromatic hydrocarbons (PAHs, 16 compounds specified on “EPA Method 610”) properties in the ash samples were investigated. In the fly ashes, the ∑16PAH (total amount of 16 PAHs) and the CPAHs (total amount of eight carcinogenic PAHs) levels varied from 0.93 µg/g to 2.08 µg/g, 0.26 µg/g to 0.87 µg/g, respectively. In the bottom ashes, ∑16PAH and the CPAHs levels varied from 2.83 µg/g to 5.32 µg/g, 1.76 µg/g to 3.76 µg/g, respectively. The CPAHs levels of some ashes, especially for the bottom ashes, are above the limits regulated by several countries, indicating that this type of coal combustion product need special treatment before landfill. Fly ashes were dominated by medium molecular weight (MMW) PAHs and low molecular weight (LMW) PAHs, while bottom ashes were abundant in the 5- and 6-ring PAHs species. Thirty-three soil samples were collected from the Luling, Liuer, and Zhangji coal mines, in the Huaibei and Huainan areas, Anhui Province, China, in 2007. The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs), identified as priority pollutants by the USEPA, were determined by gas chromatography-mass spectrometry (GC-MS). The sum of 16 US-EPA PAHs ranged from 0.13 to 3.54 μg/g (dry weight basis) with a mean concentration of 0.84 μg/g. Among the three sampling sites selected around the coal mines, the site at the Luling Coal Mine revealed maximum concentration of PAHs, while minimum concentration was observed at the site at Zhangji Coal Mine. In general, low molecular weight PAHs were predominant. Gob pile and coal preparation plant are the sources of PAHs pollution in surface soils in the vicinity of coal mines. The crops in rice paddies may adsorb some PAHs and reduces the PAHs content in soils from paddyfields. Vertical distribution of PAHs in two soil profiles indicates that PAHs contamination in soil profiles tends to occur high in the surface soils and markedly decreases with soil depth. For all depths, PAHs showed a similar distribution pattern, which is an indicator of a similar origin. Total B[a]P equivalent concentration (B[a]Peq) was found to be maximum at the Luling area, while it was minimum at Liuer zones. Organic pollutants in water have been causing serious environmental problems. Photocatalytic degradation of these pollutants using solar energy is an attractive solution to this global problem. Metal oxide semiconductor nanoparticles have been used as high activity photocatalysts; such as ZnO, TiO2, CdS, Fe2O3 and HNbO3. These semiconductors, however, can only be excited by UV light due to their large band gaps. For better utilization of sunlight and indoor illumination, it is desirable to develop photocatalysts that can be excited by visible light. We propose to develop a series of highly efficient visible light nano-photocatalyst of niobates and tantalates as well as doping these semiconductors with various metals and non-metals. Additionally, doping with metals can lead to increased photocatalytic efficiencies, while doping with non-metals can shift the optical absorption of the photocatalysts to the visible region. Our research should lead to the development of a novel, practical and marketable nanotechnology for environmental remediation. Nitrogen doped KNbO3 micro/nanostructures was synthesized by the following two procedures: First, KNbO3 micro/nanostructures were synthesized by a hydrothermal process using KOH and Nb2O5 as starting materials; The effects of KOH concentration on the morphology and particle size of KNbO3 micro/nanostructures were carefully studied. It was found that lower concentration of KOH lead to formation of nanorod, further increase of KOH concentration leads to formation of KNbO3 microcubes from the nanorod, and then the portion of the cubes increases as the reaction advances until all of the products become nanocubes. Second, nitrogen doped KNbO3 nanocubes (N-cube), that firstly exhibited good visible light photocatalytic activity of KNbO3 species, were synthesized by solid-state reaction of KNbO3 micro/nanostructures with urea at 425 ℃. Photocatalytic experiment results showed that 1) different morphology and particle size of KNbO3 can cause the change of recombination rate of photogenerated chargers and specific surface area, thus have a significant influence on the photocatalytic activity; 2) The as prepared N-cube exhibited greatly enhanced activity in the visible-light photocatalytic degradation of varies of organic contaminants and photocatalytic reduction and oxidation of water for H2 and O2 generation, which were mainly attributed to the improved surface area and increased optical absorption properties arises from the N 2p levels above the O 2p levels of the valence band. A mechanism for the photodegradation of organic contaminants by the N-cube photocatalyst under visible light is also proposed. The visible-light-sensitive photocatalyst of Ag1.4K0.6Ta4O11 nanoplates was synthesized by a facile molten-salt method, and the photocatalytic activity is evaluated by decomposition of aqueous organic contaminants containing orange G (OG), rhodamine B (RhB) and pentachlorophenol (PCP) as well as photocatalytic reduction of water for H2 generation under visible light irradiation. The Ag1.4K0.6Ta4O11 nanoplates exhibited higher photocatalytic activity on photodegradation of OG and PCP than that of Degussa TiO2 P25, but slower on the photodegradation of RhB. In addition, the activity of the Ag1.4K0.6Ta4O11 nanoplates is improved significantly by the modification with lanthanum ions. The optimal modifying content is 1mol% corresponding to the highest photodegradation percentages for photodegradation. On the other hand, the 5% La3+ modifying content exhibited highest photocatalytic activity for H2 evolution. The enhancement of photocatalytic activity after La3+ modification is attributed to the formation of nanowires, which further promote charge separation and transfer capability in the La3+ modified Ag1.4K0.6Ta4O11 nanocomposites. Notes: CityU Call Number: TD196.O73 W34 2012; xxi, 172 leaves : ill. 30 cm.; Thesis (Ph.D.)--City University of Hong Kong, 2012.; Includes bibliographical references. Sun, 01 Jan 2012 00:00:00 GMT http://dspace.cityu.edu.hk:80/handle/2031/7203 2012-01-01T00:00:00Z Selenium in Chinese coal : distribution, mode of occurrence and environmental geochemistry http://dspace.cityu.edu.hk:80/handle/2031/7202 Title: Selenium in Chinese coal : distribution, mode of occurrence and environmental geochemistry Authors: Wang, Lei (王蕾) Abstract: ﻿As is well known, selenium (Se) is one of the essential elements of human beings at low concentrations but toxic at high concentrations. Se exists as a trace element in the Earth’s crust, but coal and the black shale are known as the most Se-enriched carriers: so-called “Se-enriched sedimentary rock”. An environmental lack of Se is prevalent in most of the world and as a result, various forms of extra Se-enriched nutrition are used among people. China not only has a high incidence of endemic Se-deficiency, but also has a high incidence of environmental Se-poisoning. Among the latter, Se-poisoning incidents caused by high-Se coal combustion are the most obvious forms. Selenium is readily released during coal-combustion due to the high volatility of Se. The huge consumption amount of coal has made coal-combustion the main artificial resource of Se in the atmosphere. The content, distribution and mode of occurrence of Se in coals affects the release and migration of Se directly during the use of coal, and finally affects the environment and human health. China has abundant coal reserves produced by the long coal-forming period; thus, the sedimentary environment and coalification are comparatively complex. Systemic studies of Se in Chinese coals are meaningful work for objectively estimating the potential environmental effects of using Chinese coals. This study includes the following aspects: 1. based on the collection of 2,288 coal samples, the average Se content in Chinese coal is 3.91 mg/kg; 2. the Se content in Chinese coal varied remarkably with different provinces or areas, and three groups were defined upon Se content; 3. contents of Se falls gradually over the coal-forming period, and the average content of Se in Paleozoic coals is higher than in the Mesozoic and Cenozoic coals; 4. the content and modes of occurrence of Se in coals of different metamorphic grade were studied and discussed; 5. the formation mechanism of Se in different kinds of coal was systemic discussed; 6. Se in special coal samples (high-sulfur coal and high-chlorine coal ) were also studied. Systemic research on typical coal mining areas are helpful for further understanding of the distribution and enrichment mechanisms of trace elements in coal. Selenium contents in 123 coal and 19 surrounding rock channel samples, which were collected from the fresh working face of main coal seams in seven selected coal mines of the Huaibei coalfield (i.e. Qidong (QD), Taoyuan (TY), Renlou (RL), Haizi (HZ), Liudian (LD), Baishan (BS), and Liuer (LE)), were determined by hydride generation atomic fluorescence spectrometry. Compared with the average China and world coals, Huaibei coals were highly enriched in selenium. The depositional environment of the Permian coal-bearing strata in Huaibei coalfields was inferred by the Boron content in coal. Selenium was distributed unevenly both horizontally and vertically in this area. Pearson correlation coefficients are used to estimate the modes of occurrence of selenium in Huaibei coals. Iron-bearing clay minerals and carbonates were the dominant carriers of selenium in coals of the Lower Shihezi Formation. Selenium in coals from No. 3 and No. 10 coal seams was mainly associated with sulfide minerals. The well-developed faults in the Huaibei coalfield could contribute to the enrichment of selenium in Huaibei coals. The transformation behavior of trace elements in coal during the combustion process has been a focus of interest for a long time, but few researchers have targeted the combustion of coal slime and coal gangue. In fact, the abundant trace elements in coals also exist in coal slime and gangue, which are even more enriched. Low heat value fuels have different physical characteristics, mineral components and modes of occurrence of trace elements. Study of the emission situation of Se from low heat value power plants would be helpful in estimating the environmental risk of the coal-fired power plants more scientifically and accurately. Therefore, Selenium in feed coal, fly ash and bottom ash samples which were collected from a low-heating power plant, were studied. Result showed that Se tends to be enriched by varied degrees in different kinds of fly ash samples. This kind of distribution is shaped by two factors: first, the use of desulfurizing agents produce CaO which may react with gaseous SeO2 which is released by the high temperature; then, the honeycomb-like nature of the material and the tiny size could increase the adsorptive capacity by the enhanced specific surface area of the fly ash particles. Mass balance calculations of feed coal indicate that 80-90% of selenium in coal is distributed in the fly ash, which is captured by an electrostatic precipitator. 6.60-15.23% of the selenium may be disposed into the atmosphere directly or with the flue gas. The environmental impacts of bottom ashes may cause few environmental impacts because of the small proportions involved. The amount of selenium released into air could be very high over time, and further control is necessary for the potential environmental risk. Surface soil samples of Huaibei coal mine area have been contaminated to various degrees, according to the result of the I-geo method. The most polluted soil sample belonged to the moderately polluted category. As far as Se is concerned, the proportion of the polluted sample and the level of Se pollution both have increased from 2009 to 2011. Selenium mainly concentrated at the test site 40 cm below the surface, and then decreased with depth. This distribution pattern indicates the low immigration capacity of Se in local soils, and the high-Se site could be related to external Se sources. The contents of Se in water samples collected in 2009 and 2011 did not show visible differences. Concentrations of Se in most of the water samples are very low without any pollution evident. But there is an obvious evidence of Se enrichment and pollution in sediments and the sediment samples are mainly moderately polluted. However, considering that those water bodies are mainly used for fish-farming, Selenium in the sediment could be secondary sources. Periodic monitoring is necessary for food safety and the health of local residents. Notes: CityU Call Number: QE516.S5 W36 2012; xiv, 150 leaves : ill. 30 cm.; Thesis (Ph.D.)--City University of Hong Kong, 2012.; Includes bibliographical references. Sun, 01 Jan 2012 00:00:00 GMT http://dspace.cityu.edu.hk:80/handle/2031/7202 2012-01-01T00:00:00Z