Heavy metal distribution in soils near Palapye, Botswana: an evaluation of the environmental impact of coal mining and combustion on soils in a semi-arid region

Morupule Colliery near Palapye in eastern Botswana is the only coalmine in production in Botswana at present. Its coal is mainly used in the nearby coal-fired Morupule Power Station, which generates approximately 1,000 GWh of electricity per annum. After more than 30 years mining and more than 20 years of combustion, the sedimentation of outlet fly ash from the Morupule Power Station has increased concentrations of Cr, Ni, Zn and As by 13, 2.5, 16 and 5 ppm, respectively, in the fine portion (<53 μm) of surface soils for approximately 9 km downwind. Elements that have higher concentrations in coal have stronger small-particle association during coal combustion and are less mobile in surface soils, thus showing stronger contaminations in surface soils around the coal-fired plant. Although the degree of contamination of Cr, Ni, Zn and As from coal combustion in the Palapye area at present is low, it is necessary to monitor concentrations of these elements in surface soils routinely in the future. This study also reveals moderate Pb and Zn contaminations in the Palapye area. The former is due to the use of leaded petroleum in motor vehicle traffic and the latter is mainly due to the use of galvanized iron sheets in construction.     

Characterization of Santa Catarina (Brazil) coal with respect to human health and environmental concerns

The current paper presents the concentration, distribution, and modes of occurrence of trace elements of 13 coals from south Brazil. The samples were collected in the state of Santa Catarina. Chemical analyses and the high ash yields indicate that all studied coals are rich in mineral matter, with SiO₂ and Al₂O₃ dominating as determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Quartz is the main mineral species and is associated with minor levels of feldspars, kaolinite, hematite, and iron-rich carbonates. The contents of trace elements, including As, Pb, Cd, Ni, Cr, Mn, Be, V, U, Zn, Li, Cu, Tl, and Ni, in coals were determined. A comparison of ranges and means of elemental concentrations in Santa Catarina, Brazil, and world coals shows that the ranges of most elements in Santa Catarina coal are very close to the usual worldwide concentration ranges in coal.     

Fluorosis caused by indoor coal combustion in China: discovery and progress

In this study, investigations into endemic fluorosis were conducted and fluorine concentration in environmental samples determined. In an indoor coal-combustion-type fluorosis area, local clay was used to mix with coal for indoor combustion. There are two key steps in the procedure of the indoor transition of fluorine: indoor wet corns and vegetables strongly absorbed fluorine from indoor air; and fluorine strongly accumulated in clay, which was mixed with coal for combustion. Therefore, with the increasing of the percentage of clay in the clay-mixed coal as well as corn in foodstuff, the ratio of fluorosis will be increased.     

Endemic Arsenosis Caused by Indoor Combustion of High-As Coal in Guizhou Province, P.R. China

The arsenic (As) content of coal relating with mineralization of gold in Southwest Guizhou Province, China is up to 35,000 ppm. The coal is burned indoors in open pits for daily cooking and crop drying. As a result, arsenic is precipitated and concentrated in corn (5–20 ppm), chili (100–800 ppm) and other foods. Arsenic concentrations in the drinking water of high-As coal areas are lower than 50 ppb. The estimated main sources of As exposure in this area are from polluted food. Approximately, 3000 arsenosis patients were found by 1998, and more than 100,000 people from six counties were under the threat in China. This paper presents the major ingestion pathway of this type arsenosis and relative geochemistry of high-As coal. The project supported by National Natural Science Foundation of China (NSFC 40133010).     

中国煤中氮的含量及其分布

为了解我国煤中氮的含量水平及其分布特征,在全国主要产煤的26个省、市、区,根据各煤田的地质储量、成煤时期和煤变质程度,兼顾各矿区的煤炭产量,采集306个煤样,测定了全部样品的氮含量,并对各成煤时代、各聚煤区、各省市区的煤氮含量进行了统计分析。研究表明:煤中氮主要以有机形态赋存;氮含量与煤变质程度间有微弱的正相关关系;全国煤的氮含量近似服从正态分布,90%的样品含氮范围为0.52%～1.41%,宜用算术平均值0.98%作为全国平均煤氮含量。