陈家山矿煤中微量元素和稀土元素地球化学特征

通过对陈家山煤矿中下侏罗统延安组4^#主采煤层中微量元素和稀土元素的测试分析,发现煤中富集亲花岗岩的钨钼族元素W、Mo、Bi、Sn、Ba、Sr和Li,说明该区煤系形成期间的陆源碎屑主要来自花岗岩和花岗片麻岩等中、酸性岩石。4^#煤中ΣREE平均值为98.2×10^-6,稀土元素分布模式十分相似,呈左高右低的宽缓“V”型曲线,Eu负异常明显,反映出稀土元素与陆源碎屑岩关系密切,成煤期间稀土元素来源一致,陆源物质的供应相对稳定。     

淮南煤田煤矸石中环境意义微量元素的丰度

淮南煤田矿区开采历史长,煤矸石累计堆存量大,从环境意义角度研究该矿区煤矸石具有其典型性和现实性.根据煤矸石来源、矿区主采煤层和岩性特征,在井下煤系地层系统采集原始煤矸石样品44件,运用现代环境微量元素分析技术(INAA和ICP-MS)测定了煤矸石中46种微量元素,并用冷原子吸收法分析Hg、选择性电极法分析F.进而筛选出11种具有环境意义的有害元素:10种金属元素(Cd、Cu、Ni、Sn、Hg、Mn、As、Cr、Pb、Zn)和1种非金属元素F.并以总量法初步预测和评估这些元素的含量水平和潜在的环境影响.与淮南煤及其土壤、世界煤、华北泥岩的对比可知,煤矸石中Cd、Cu、Mn、Ni、Pb、Sn等超出土壤背景值,有必要对这些元素在矿区环境污染迁移性和累积件的环境效应进行深入调查研究.     

Evaluation of trace element contents in groundwater in Abakaliki metropolis and around the abandoned mine sites in the southern part, Southeastern Nigeria

This study aimed at determining the concentrations of trace elements in the groundwater of Abakaliki urban and some abandoned mine sites in the Southern part. Sixteen trace elements were analyzed for each of the twenty water samples collected. Laboratory results showed that the concentration of manganese varied from 4.816 to 11.238 ppm, zinc from 0.126 to 1.403 ppm, copper from 0.198 to 0.967 ppm, lead from 0.005 to 0.010 ppm, arsenic from 0.001 to 0.009 ppm, chromium from 0.009 to 0.025 mg/l, cadmium from 0.003 to 0.011 mg/l, mercury from 0.001 to 0.005 mg/l, nickel from 0.008 to 0.032 mg/l, selenium from 0.001 to 0.011 ppm, iodine from 0.013 to 0.050 ppm, uranium from 0.001 to 0.006 ppm, platinum from 0.009 to 0.032 ppm, tin from 0.014 to 0.015 ppm, lithium from 0.009 to 0.024 mg/l, cobalt from 0.015 to 0.036 mg/l, and iron from 0.010 to 0.980 ppm. These results were analyzed statistically and their distribution modeled using a software package. The results were also compared with world standards for potable water. The comparison showed that water samples are contaminated with trace elements and particularly polluted with, Mn, Hg, and Cd with average concentration values of 8.43, 0.002, and 0.005 mg/l, all above the World Health Organization standard limits of 0.005, 0.001 and 0.003 mg/l, respectively. Concentrations of Fe, Zn, and Ni are above the permissible limits of 0.30, 0.01, and 0.02 mg/l, respectively, in some places. Health hazards like metal poisoning which can result from pollution of this nature cannot be ruled out. Controlling processes such as chemical dissolutions, mechanical weathering and pollution from urban sewage, release the trace elements to the soil system while chemical dilution, otherwise called leaching, streamlines the trace element plumes to the groundwater regime with dispersion processes mixing and spreading the plume. Dispersion trends of the elements show point sources from the southern part, indicating presence of ore deposits, most likely sulfide ores as interpreted from correlation matrix.     

Environmental Constraints and Part-time Farming in Southeastern Nigeria

In southeastern Nigeria where population pressure is a problem of accelerating importance the agricultural land is in short supply thereby necessitating off-farm jobs to supplement farm income. There is therefore, a high incidence of part-time farming in the region. Analysis of the operational characteristics of thirty-six villages confirms that the intensity of part-time farming varies spatially according to the severity of environmental degradation resulting from population pressure. In addition, villages around urban/industrial centres participate actively in part-time farming since opportunities for off-farm employment are relatively higher. The situation in southeastern Nigeria is used to illustrate the prospects and problems of part-time farming in a developing economy. The implications of part-time farming on the agricultural economy and on rural development generally are examined. Policy measures are suggested that will direct the co-existence of part-time farming with work in the off-farm sector in order to achieve a beneficial and integrated rural development.     

Arsenic and antimony contamination in the vicinity of Yata gold mine, Guizhou, China

The ores of the Yata gold mine in China are rich in arsenic and antimony, so the exploitation of this mine may also lead to the release of As and Sb to adjacent environments, such as stream water, stream sediment, soil, plants, and crops. To understand the environmental impact of mine tailings, samples of water, sediment, soil, plant and crop were collected and analyzed. In summer of 2005, the tailings dump was seriously flushed by a heavy flood, and the mine waste was transported far away. Samples were collected in December of 2004 and January of 2006, respectively, and the impact of the flood on the release of toxic elements was evaluated. The result shows that the Yata creek, which drains the mining area, was severely contaminated by As and Sb. The dissolved As and Sb in water are 86-1140 μg/L and 65-370 μg/L, the particulate As and Sb are 38-2100 μg/L and 25-420 μg/L, whereas As and Sb in the sediment are 190-760 μg/g and 69-210 μg/g, respectively. In water environment, As and Sb show a similar feature to SO4^2- since As and Sb exist dominantly as anions--H2AsO4^-, HAsO4^2- and SbO3^-. In contrast to Fe, Cu, Pb, Zn, which migrate mostly in particulate form, As and Sb tend to transport in dissolved form.     

Copper contamination of soils and vegetables in the vicinity of Jiuhuashan copper mine,China

Copper contamination in soils and vegetables in the vicinity of an abandoned copper mine in China was investigated. The Cu concentrations of 93 soil samples ranged from 30.4 to 3,191 mg kg⁻¹ soil for a mean of 816.8 mg kg⁻¹ soil. Among 15 samples from a 0 to 20-cm soil layer used for the toxicity characteristic leaching procedure (TCLP) test, the highest value of Cu-TCLP was 133.8 mg kg⁻¹ soil and the TCLP values were positively correlated with the total Cu content of the soils. The sequential extraction of soils in the 0–20-, 20–40-, and 40–60-cm soil layers showed that Cu existed mainly in the Fe–Mn oxide fraction, sulfide/organic fraction, and residual fraction. The copper contamination of 21 species of vegetables from in situ sampling was also examined. Cu concentrations in the edible portions of Brassica chinensis and Solanum melongena were higher than the FAO/WHO standard (40 mg kg⁻¹ DW). The health risk of copper for local inhabitants from consuming these vegetables was assessed on the basis of the target hazard quotient. Enriched concentrations of copper were also found in situ in eight cultivars of B. chinensis planted in the fields, with two levels of Cu concentration. The results showed that there is severe copper contamination in this mine area, and the pollutant in soils show a high risk of leaching into the groundwater and diffusing through the food chain.     

Contamination of the environmental ecosystems by trace elements from mining activities of Badao bone coal mine in China

Bone coal, as a main mining object, can be used by local inhabitants as daily fuel and by local industrial enterprises as industrial fuel in Pinglin County, Shaanxi Province, China. This study reports how the environmental ecosystems have been polluted around the Badao bone coal mine. Geochemical samples (e.g. rock, water, soil, edible plant and animal) were collected. Bone coal from the Badao mine contains Se up to 75 µg/g Se and 28 µg/g Se in ashes after its combustion, with higher contents of other trace elements. Bone coal and its ash seem to be the main geochemical source of trace elements in soils and plants, which may cause contamination of the local environmental ecosystems. Three ways by which soils have been contaminated by these trace elements derived from bone coal are proposed in this paper. Radishes and beans have the ability to accumulate Mo and Se from soils. There is no obvious difference in concentrations of Cu, Cr and F in each plant from the two areas.     

Socio-economic impacts of ecotourism attractions in Enugu state,Nigeria

The study examined the socio-economic impacts of ecotourism attractions in Enugu State with special interest to investigate the trending benefits, effects and challenges of ecotourism development in the State. Questionnaire survey and interview guided by participatory rural appraisal techniques were employed to elicit needed information. The findings of the study revealed that the ecotourism industry in the area attracted benefits such as; provision of jobs, business opportunities, improved family income, patronage of local products and improved transport system. Irrespective of these benefits, the study also revealed that there were accruing challenges such as; lack of trained labor power, lack of government interest, lack of private sector participation, poor administration of the ecotourism sites, inadequate security, lack of standard supermarkets and poor accommodation facilities. Based on these findings, the study recommended that all stakeholders of the tourism industry should participate actively in all stages of ecotourism development in the area and that tourism should be enrolled as one of the core subjects or course in the secondary schools, colleges and universities to improve the awareness of the local people and improve the labor power.     

煤矸石中微量元素的地球化学行为

以兖州矿煤矸石中微量元素的淋滤作用及析出含量为例,分析了微量元素在洗选过程和淋滤作用下的分布、迁移规律等地球化学行为。在用不同的pH值酸性溶液作淋滤实验时发现,pH值对微量元素的析出影响很大。研究还发现土壤中微量元素的富集量随着距矸石堆距离的增加呈明显的下降趋势。     

Rare-earth elements as source indicators of Pan-African granites from Obudu Plateau,Southeastern Nigeria

The rare-earth element （REE） concentrations of representative granite samples from the southeast of the Obudu Plateau, Nigeria, were analyzed with an attempt to determine the signatures of their source, evolutionary history and tectonic setting. Results indicated that the granites have high absolute REE concentrations （190×10^-6-1191×10^-6; av.=549×10^-6） with the chondrite-normalized REE patterns characterized by steep negative slopes and prominent to slight or no negative Eu anomalies. All the samples are also characterized by high and variable concentrations of the LREE （151×10^-6-1169×10^-6; av.= 466×10^-6）, while the HREE show low abundance （4×10^-6-107×10^-6; av.=28×10^-6）. These are consistent with the variable levels of REE fractionation, and differentiation of the granites. This is further supported by the range of REE contents, the chondrite-normalized patterns and the ratios of LaN/YbN （2.30-343.37）, CeN/YbN （5.94-716.87）, LaN/SmN （3.14-11.68） and TbN/YbN （0.58-1.65）. The general parallelism of the REE patterns, suggest that all the granites were comagmatic in origin, while the high Eu/Eu＊ ratios （0.085-2.807; av.=0.9398） indicate high fo2 at the source. Similarly, irregular variations in LaN/YbN, CeN/YbN and Eu/Eu＊ ratios and REE abundances among the samples suggest behaviors that are related to mantle and crustal sources.     

Heavy metal concentrations in soils and plants in the vicinity of Arufu lead-zinc mine,Middle Benue Trough,Nigeria

This study focused on the influence of base metal mining on heavy metal levels in soils and plants in the vicinity of Arufu lead-zinc mine, Nigeria. Soil samples (0-15 cm depth) and plant samples were collected from cul-tivated farmlands in and around the mine, the unmineralized site and a nearby forest (the control site). The samples were analyzed for heavy metals (Fe, Zn, Mn, Cu, Pb, Cr and Cd) by Atomic Absorption Spectrophotometry (AAS). The physical properties of soils (pH and LOI) were also measured. Results showed that soils from cultivated farm-lands have neutral pH values (6.5-7.5), and low organic matter contents (10%). Levels of Zn, Pb and Cd in culti-vated soils were higher than the concentrations obtained from the control site. These heavy metals are most probably sourced from mining and agricultural activities in the study area. Heavy metal concentrations measured in plant parts decreased in the order of rice leavescassava tuberspeelings. In the same plant species, metal levels decreased in the order of ZnFeMnCuPbCrCd. Most heavy metals were found in plant parts at average concentrations normally observed in plants grown in uncontaminated soil, however, elevated concentrations of Pb and Cd were found in a few cassava samples close to the mine dump. A stepwise linear regression analysis identified soil metal contents, pH and LOI as some of the factors influencing soil-plant metal uptake.     

Origin of acid mine drainage in Enugu

Mine flooding is a serious problem in the Enugu Coal Mines and has led to the abandonment of two of the four mines. About 1800 m³ of water is pumped out daily from the mines into the nearby streams. The source of this enormous volume of water has been established based on the hydrodynamics and hydrology of the area. It is shown that although two prolific aquifers—an unconfined and a confined system—overlie the mines, the mine water is derived principally from the unconfined aquifer. The pathway of flow is, however, provided by the numerous fractures connecting the two aquifers and the mine tunnel.The major hydrochemical activity resulting in pollution of the mine water occurs within the sumps in the floor of the longwalls. These sumps act as oxidation chambers where groundwater from the fractures is mixed and subsequently reacted with sulfur-rich solutes released by coal mining.Contrary to general belief, the mine drainage has not seriously degraded the chemistry of receiving streams. The pH, electric conductivity and, thus, the dissolved ions were increased less than 10% of the values in the unaffected region.     

Spatial variability of topsoil contamination with trace elements in preschools in Vilnius,Lithuania

An investigation of the spatial variability of topsoil contamination level was performed in 49 preschool playgrounds located in Vilnius city and correlated with urban (height and age of the preschools and height of surrounding buildings) and natural (altitude) factors. Composite samples, consisting of 20–30 sub-samples, were collected from 10 cm topsoil layer with a 3–5 m distance from each other. Sieved fraction (< 0.63 mm) was ashed at 400 °C, ground to < 1.0 μm and analysed for the real total concentrations of 22 trace elements (Ag, B, Ba, Co, Cr, Cu, Ga, Li, Mn, Mo, Nb, Ni, Pb, Sc, Sn, Sr, Ti, V, Y, Yb, Zn and Zr) using optical atomic emission spectrophotometry. Information on construction year and height (number of building stories) of preschool and surrounding buildings was acquired from the Centre of Registers of Lithuania. Out of 22 analysed elements, 13 to a greater extent exceeded the background values in several areas and were used to calculate the total contamination index (Z_s13). Out of 49 analysed areas, 21 had moderately hazardous to hazardous levels of contamination as indicated by Z_s13. The main contaminating elements, exceeding the permissible concentrations were Ag, Cu, Mo, Pb, Sn and Zn, the origins of which coincide with city industry and traffic. Topsoil around the newer preschool buildings, despite their location, contained lower concentrations of contaminants, while areas at higher altitudes were more contaminated than those located at lower altitudes. The latter causality is biased, as the city industry, and hence the highest contamination, is in districts located higher above sea level than the remaining studied sites.     

Concentration and association of minor and trace elements in Mukah coal from Sarawak, Malaysia, with emphasis on the potentially hazardous trace elements

The ash yield and concentrations of twenty-four minor and trace elements, including twelve potentially hazardous trace elements were determined in Mukah coal from Sarawak, Malaysia. Comparisons made to the Clarke values show that Mukah coal is depleted in Ag, Ba, Be, Cd, Co, Mn, Ni, Se, U, and V. On the other hand, it is enriched in As, Cr, Cu, Pb, Sb, Th, and Zn. Among the trace elements studied, V and Ba are associated predominantly with the clay minerals. Manganese, Cr, Cu, Th, and Ni are mostly bound within the aluminosilicate, sulphide and/or carbonate minerals in varying proportions, though a portion of these elements are also organically bound. Arsenic, Pb and Sb are mostly organically bound, though some of these elements are also associated with the sulphide minerals. Zinc is associated with both the organic and inorganic contents of the coal. Among the potentially hazardous trace elements, Be, Cd, Co, Mn, Ni, Se, and U may be of little or no health and environmental concerns, whereas As, Cr, Pb, Sb and Th require further examination for their potential health and environmental concerns. Of particular concern are the elements As, Pb and Sb, which are mostly organically bound and hence cannot be removed by physical cleaning technologies. They escape during coal combustion, either released as vapours to the atmosphere or are adsorbed onto the fine fly ash particles.     

Mobility of some potentially toxic trace elements in the coal of Guizhou, China

 The mobility of 10 potentially toxic trace elements (PTTE), As, Cd, Cr, Cu, Hg, Ni, Pb, Se, Tl, and Zn from 32 coals of the Longtan Group formed in Permian Period in Guizhou Province, China was investigated using sequential extraction procedures. The results demonstrate that PTTEs such as Hg, As, Se, Cd, Cu, and Pb have the highest mobility at surface conditions, and the average extractable fractions of them are 86%, 95%, 79%, 76%, 69%, and 69% of the total amount in coal, respectively. The elements in coal with the lowest leachability include Tl, Cr, and Ni, and the average extractable fractions of them are 30%, 20%, and 29% of the total amount in coal respectively. Zinc has an intermediate behavior, and the average leachable fraction of it accounts for 46% of the total amount in coal. The results demonstrate that mobility of PTTE in coal depends on the speciation of these elements. The elements associated with sulfates, carbonates, sulfides and some organic matter in coal show the highest extraction rates during the weathering process, while elements with silicate affinities are inert at surface conditions. Received: 29 December 1998 · Accepted: 10 November 1998     

Geochemical characteristics of REY,Li, Ga trace elements in the No. 9 coal seam of the Daheng mine,Ningwu coalfield,Shanxi Province,China

To understand the geochemical characteristics of the No.9 coal in the Daheng Mine of the Ningwu coalfield, the trace element analysis was conducted through X-ray fluorescence spectroscopy (XRF) and inductively coupled plasma mass spectrometry (ICP-MS). The sedimentary environment was discussed according to the element geochemical parameters. The results show that Li, Ga, Hf, Zr, Nb, Th, and Ta are slightly enriched in the No. 9 coal of Daheng Mine. The average value of the rare earth elements and yttrium (∑REY) in coal here is 144.20 μg/g (excluding parting), which is higher than the average value of ∑REY in the world ’s coal and China ’s coal. The light rare earth elements (LREY) are enriched. The content of Eu was 0.12–2.10 μg/g with an average of 0.57 μg/g, and the Eu is obviously negatively abnormal. Most of the trace elements in the coal are positively correlated with the ash content, which shows that the occurrence of these trace elements is related to inorganic minerals. The results of sequential chemical extraction experiments show that rare earth elements mainly exist in coal in the form of aluminosilicate. The value of the Sr/Ba and the content of S reflect that the coal-forming environment was influenced by seawater. The values of V/Cr and Ni/Co reflect that the peat swamp is in an anaerobic environment and a strongly reducing environment during the coal-forming period.     

兖州矿区煤中某些微量元素的赋存状态研究

微量元素的赋存状态决定其在煤的加工利用过程中释放的难易程度和毒性，弄清其在煤中的赋存状态，对准确评价元素的工艺性能、环境影响、作为副产品的可能性以及在地质意义上都是十分重要的。分析了微量元素在煤中的有机亲合性，采用数理统计方法，求得了微量元素与煤中有机显微组分、三态硫、灰分之间的相关性，并在浮沉实验的基础上，分析了微量元素的存在状态，通过研究向知，Ge、Ga、U、V、Cu、Th、Pb和Zn主要以无机态存在于煤中，F和Cl可能以有机态存在为主，As无机态和有机态存在的机率相似。     

Migration and contamination of major and trace elements in groundwater of Madras city,India

Groundwater samples collected from both open and bore wells in an area of about 270 km² from Madras City, India, have been analyzed for major ions (HCO₃, Cl, Si, Na, Ca, and Mg) and trace elements (As, Se, B, V, Cr, Fe, Co, Pb, Cu, Zn, Cd, Mn, Ni, Mo, and Ba). The study reveals that the quality of potable water has deteriorated to a large extent. Seawater intrusion into the aquifer has been observed in nearly 50 percent of the study area. The toxic elements (As and Se) have already exceeded the maximum permissible limits of drinking water in almost the entire city. A positive correlation of As and Se with other toxic metals such as V, Cr, Fe, B, etc., indicates that all these elements are anthropogenic in origin. Applying multivariate analysis, the source for trace elements in groundwater has been grouped into two major factors: pollution and mobilization factors. The groundwater in the study area is largely contaminated by organic effluents and reflects the intensity of pollution caused by the overlying soil sediment and rapid infiltration of the pollutants.