Liu Guijian

Health Effects of Arsenic, Fluorine, and Selenium from Indoor Burning of Chinese Coal

Chinas economy has developed rapidly in the last two decades, leading to an increase in energy consumption and consequently emissions from energy generation. Coal is a primary energy source in China because of its abundance and will continue to be used in the future. The dominance of coal in energy production is expected to result in increasing levels of exposure to environmental pollution in China. Toxic trace elements emitted during coal combustion are the main sources of indoor air pollution. They are released into the atmosphere mainly in the forms of fine ash and vapors and have the potential to adversely affect human health. Those trace elements, which volatilize during combustion, are hazardous air pollutants (HAPs) and are particularly rich in Chinese coals. Among the HAPs, arsenic (As), fluorine (F), and selenium (Se) have already been identified as pollutants that can induce severe health problems. In this review, the geochemical characteristics of As, F, and Se, including their concentration, distribution, and mode of occurrences in Chinese coal, are documented and discussed. Our investigations have confirmed the current As- and F-induced epidemics in Guizhou (Southwest China) and Se epidemic in Hubei (Northeast China). In this study, diagnostic symptoms of arseniasis, fluorosis, and selenosis are also illustrated.

Geochemical Characters of Water Coproduced with Coalbed Gas and Shallow Groundwater in Liulin Coalfield of China

To reveal the geochemical characters of water coproduced with coalbed gas and shallow groundwater, water samples were collected from 12 wells of coalbed methane and 7 wells of shallow groundwater. The pH, CODMn, fCO(2), total dissolved solids (TDS), total hardness, and concentrations of metasilicic acid, sodium and kalium, calcium ion, magnesium ion, ammonium iron, bicarbonate ion, carbonate, chloride, sulfate ion, nitrate ion, fluoride, lithium, zinc, nickel, manganese, iron, boron, barium, etc. of the samples were measured. Research results showed the following: (1) Concentrations of TDS, chloride, fluoride, sodium and kalium, ammonium, iron, and barium in the water coproduced with coalbed gas exceeded the national standards of China; however, physical, chemical, and biological properties of shallow groundwater could meet the national standard. (2) The water produced from coalbed contained mainly Na-Cl center dot HCO3, with average TDS of 4588.5 ppm, whereas shallow groundwater contained a mixture of chemicals including Na center dot Mg center dot Ca-HCO3 center dot SO4 and Na center dot Mg-HCO3 center dot SO4, with average TDS of 663.8 ppm. (3) In general, it was observed that bicarbonate and sodium accumulated in a reducing environment and deeper system, while depletion of hydrogen ions and dissolution of sulfate, calcium, and magnesium occurred in a redox environment and shallow system. (4) Sodium and kalium, ammonium, chloride, and bicarbonate ions were the main ions found in the study area.

Characteristics of coal ashes in Yanzhou mining district and distribution of trace elements in them

In the process of combustion of coal organic and inorganic materials in it will undergo a complex variation. Part of them will become volatiles and, together with coal smoke, enter into atmosphere, some will remain in micro-particulates such as ash and dust and find their way into atmosphere in the form of solid particles, and the rest will be retained in ash and slag. Coal ashes are the residues of organic and inorganic substances in coal left after coal combustion and the composition of coal ashes is dependent on that of minerals and organic matter in coal. This paper deals with the chemical composition of coal ashes, the distribution of trace elements in them and their petrological characteristics, and also studies the relationship between the yield of coal ashes and the distribution of trace elements. In addition, a preliminary study is also undertaken on the factors that affect the chemical composition of coal ashes. As viewed from the analyses of coal ash samples collected from the Yanzhou mining district, it can be seen clearly that coal ashes from the region studied are composed chiefly of crystalline materials, glassy materials and uncombusted organic matter and the major chemical compositions are SiO2, Al2O3, Fe2O3, and CaO, as well as minor amounts of SO3, P2O5, Na2O, K2O and TiO2. During the combustion of coal, its trace elements will be redistributed and most of them are enriched in coal ashes. At the same time, the concentrations of the trace elements in flying ash are much higher than those of bottom ash, i.e., with decreasing particle-size of coal ashes their concentrations will become higher and higher. So the contents of trace elements are negatively proportional to the particle-size of coal ashes. There has been found a positive correlation between the trace elements Th, V, Zn, Cu and Pb and the yield of coal ashes while a negative correlation between Cl and the yield of coal ashes.

Thermal Ionization Mass Spectrometry (TIMS)-U-Series Ages of Corals from the South China Sea and Holocene High Sea Level

Coral samples collected from the waters off the Leizhou Peninsula, the Hainan Island and the Yongxing Island of the Xisha Islands were analyzed by thermal ionization mass spectrometry (TIMS) and multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) for their U-Th systematics. Their uranium contents are mostly lower than 3μg/g, and the δ234U (T) values are within the range of 150 ±5. X-ray diffraction analysis showed that the corals are all composed of aragonite. This demonstrates that the corals determined have maintained a close system for 7000 years and their skeletons bear much information about the primitive tropical marine environment. The highly precise age sequence of the corals determined has revealed that there occurred three phases of high sea level in the South China Sea waters, which are dated at 6799-6307 a B. P., 4472-4285 a B. P. and 1279-1012 a B. P., respectively. The three phases lasted 492 a, 187 a and 267 a, respectively. These three phases of high sea level are corresponding to the warm environments that had appeared in China during the Megathermal Period and the Medieval Warm Period in the past ten thousand years.