Weathering fluxes of arsenic from a small catchment in Slovak Republic

Inputs of As to a small catchment due to chemical weathering of bedrock, mechanical weathering of bedrock, and atmospheric precipitation were 71.53, 23.98 and 0.02 g ha⁻¹ year⁻¹, respectively. The output fluxes of As due to mechanical erosion of soil, biological uptake, stream discharge, and groundwater flow were 6.32, 4.77, 0.37 and 0.02 g ha⁻¹ year⁻¹, respectively. The results indicate that arsenic accumulates in soil and regolith with a very high rate. This is attributed to the selective weathering and erosion with respect to arsenic and fixation of arsenic in the secondary solids produced by weathering. The output fluxes of As in stream and groundwater in Vydrica catchment in Slovak Republic (0.39 g ha⁻¹ year⁻¹) based on muscovite–biotite granites and granodiorites were much lower compared to catchments in a gold district in the Czech Republic. These results may be ascribed to the low levels of arsenic pollution measured in Vydrica catchment. The arsenic fluxes were estimated by calculation of mechanical and chemical weathering rates of the bedrocks in Vydrica catchment from mass balance data on sodium and silica. The justification of the steady state of Na and Si is that neither of the elements is appreciably accumulated in plants and in exchangeable pool of ions in soil.     

Liptinite in coal and oil source rocks in northern Thailand

Palynological study of northern Thailand coal and oil deposits indicates a similar palynological association to that of the Borneo region. Coal petrographic studies of these deposits show variations in the liptinite macerals, especially alginite types. The oldest of these coal and oil deposits, which are of Late Oligocene to Early Miocene age, are dominated by Botryococcus sp. or Botryococcus-related algae. Thick-walled lamaginites and spores and pollen of temperate affinity, are found in some areas. By contrast, thin-walled lamaginite is dominant in late Middle Miocene time. Resinite, suberinite, and cutinite are dominant in forest swamp coal deposits whereas alginite, cutinite and lycopodium spores are dominant in lacustrine environments. Exsudatinite is common even at early levels of maturation. These liptinite macerals can be major sources of oil and gas.     

粤北大宝山矿酸性排水中铅元素环境地球化学

粤北大宝山铁多金属矿床的开发给环境带来了严重的危害。采选冶产生的酸性排水及固体废弃物堆积的淋滤酸水,携带浸滤出的大量重金属离子流入下游河道,严重影响矿区及酸水流域的生态环境。结果表明,河流水中高Pb含量直接源于尾砂,并受水体pH值的显著影响。河流底泥能够大量聚集水体中的Pb,在水体pH值降低时,相对稳定存在的Pb会被再次从河流底泥中释放出来,形成河流二次污染。土壤中Pb含量受土壤pH值和土壤粒度的影响,食用蔬菜中Pb的高含量由土壤Pb高含量决定,并受土壤pH值的影响,通过改善农业灌溉水质,提高土壤pH值,可以降低蔬菜重金属Pb含量。     

Recultivation and renewal of a balanced landscape in the lignite mining area of the Rhineland

The lignite mining area of the Rhineland provides an excellent example for planned recultivation of large open-works. In order to properly carry out recultivation measures, it is necessary to conduct basic research on the ecological factors which compose a balanced landscape. The problems involved in reconstructing a landscape, which has been pitted by large-scale open-cut mines, are discussed from the aspects of: planning and construction of a new landscape-relief, proposed agricultural and forestry use, nature preserves and resort areas. The aim of recultivation, from the ecological point of view, is to renew the natural biological potential and to reform the landscape, so as to provide the healthiest environment for Man.     

A geochemistry study of arsenic speciation in overburden from Mae Moh Lignite Mine, Lampang, Thailand

The aim of this study was to investigate the geochemical characteristics of arsenic in the solid material samples of the Mae Moh Mine and also the Mae Moh power plants fly ash samples were systematically studied. Arsenic concentration in overburden, coal lignite and fly ash are variable (depending on source of solid samples). The results show that the strata of overburden, J seam of coal and fly ash are rich in arsenic and also relatively soluble from fly ash; it occurs as a surface precipitate on the ash particle. The experimental study on speciation in the strata also indicates that the arsenic speciation of Mae Moh solid samples are mainly arsenate, As (V), which are approaching exceed 80%. Arsenic content in the main of overburden is in the range of 14.3–888.8 mg/kg, which is larger than the arsenic background soil values. Solid materials polluted wastewater; the arsenic speciation was present predominantly as arsenate in the surface water of a series of Mae Moh solid materials basins.     

An integrated geophysical study of arsenic contaminated area in the peninsular Thailand

Geophysical surveys were carried out in an arsenic contaminated area, in the Ron Phibun District in southern Thailand. Here, tin and associated minerals, i.e. arsenopyrite and pyrite, have been extracted from granites and natural processes and the mining activities led to arsenic contamination in the environment. Electrical resistivity and self-potential (SP) were used to define the distribution of arsenic contamination in the groundwater. Resistivities of 25–100 Ωm and a positive SP anomaly of 66.0 mV were observed in an area where the arsenic content in auger water at 3.5–5.0 m depths was high, 0.5–5.0 mg/l. Integrated interpretation of resistivity, seismic refraction, GPR and gravity data gave a clear image of subsurface shallow structures (< 30 m depths). There was a good correlation between the resistivity and the gravity data. A subsurface rise was found, which possibly acts as a naturally buried dam, separating a high-contaminated area from a low contaminated area.     

Impacts of karst paleo-sinkholes on mining and environment in northern China

The karst paleo-sinkhole is a special geological structure widely found in the coal measures of northern China. Some paleo-sinkholes have high permeability and connectivity, making them excellent connectors between the karst aquifer and the coal seam. Consequently, during coal extraction disastrous water inrushes take place frequently, which cause severe loss not only in mine submersions and personnel casualties, but also in environmental quality. Locations and the geological and hydrogeological characteristics of paleo-sinkholes in northern China are presented. In-situ drilling and excavation results show that paleo-sinkholes have different hydrogeological behaviors in different regions and in different mines. Based on observed data, mining-induced strata failure in the seam floor is analyzed. The existence of paleo-sinkholes increases the floor strata failure zone. Numerical simulation then is adopted to model coal mining with the effects of both the paleo-sinkholes and the water pressure in the confined aquifer. Analyses of the simulation conclude that the paleo-sinkhole induces the increase in the strata failure and deformation. These make water inrushes more likely to happen.     

Organic geochemistry of Amynteo lignite deposit,northern Greece: a Multi-analytical approach

Several lignite samples were collected from boreholes of the Amynteo opencast lignite mine, northern Greece. Organic geochemical characteristics were investigated with the help of various analytical techniques, comprising Gas Chromatography (GC) and Gas-chromatography-Mass Spectrometry (GC-MS), Fourier Transform Infrared Spectroscopy (FTIR), solid-state Nuclear Magnetic Resonance (NMR) and Electron Paramagnetic Resonance (EPR) spectroscopy, petrographical measurements as well as determination of bulk parameters. In the low rank (Rr = 0.21%) Amynteo lignites, huminite is the most abundant maceral group, inertinite has relatively low percentages and liptinite concentrations are rather high. Carbon Preference Index (CPI) reveals the predominance of odd-numbered, long-chained aliphatic hydro-carbons, which is related to a higher terrestrial plant input. The Pr/Ph ratio suggests that reducing conditions were persistent during peatification. Gymnosperm biomarkers such as isoprimarane, abietane, phyllocladane and sandaracopimarane, as well as angiosperm indicators (lupane) and hopanoid compounds with bacterial origin were identified. Analyses of the aromatic fractions revealed the presence of naphthalene, alkyl benzenes and phenols, pyrene, cadalene, cadinane, fluoranthene and dibenzofurane. Based on the FTIR analysis, aliphatic and oxygen containing structures were prevailed over the aromatic moieties. The intensity of the mineral bands was preferentially increased in the FTIR spectra of insoluble material. According to NMR analysis, the aliphatic carbons (0–50 ppm) have higher proportions comparing to aromatic carbons (100–160 ppm). The aromaticity fraction is low (fa = 0.32), as expected for these low rank coals. The presence of free organic radicals and Fe³⁺ and Mn²⁺ paramagnetic ions was revealed by EPR. In summary, the combined application of complementary analytical techniques allowed a deep inside into the geochemical characteristics of Amynteo lignites.     

Geochemical modeling of arsenic sulfide oxidation kinetics in a mining environment

Arsenic sulfide (AsS (am), As₂S₃ (am), orpiment, and realgar) oxidation rates increase with increasing pH values. The rates of arsenic sulfide oxidation at higher pH values relative to those at pH∼2 are in the range of 26-4478, 3-17, 8-182, and 4-10 times for As₂S₃ (am), orpiment, AsS (am), and realgar, respectively.Numerical simulations of orpiment and realgar oxidation kinetics were conducted using the geochemical reaction path code EQ3/6 to evaluate the effects of variable DO concentrations and mineral reactivity factors on water chemistry evolution during orpiment and realgar oxidation. The results show that total As concentrations increase by ∼1.14 to 13 times and that pH values decrease by ∼0.6 to 4.2 U over a range of mineral reactivity factors from 1% to 50% after 2000 days (5.5 yr). The As release from orpiment and realgar oxidation exceeds the current U.S. National Drinking Water Standard (0.05 ppm) approximately in 200-300 days at the lowest initial dissolved oxygen concentration (3 ppm) and a reactivity factor of 1%. The results of simulations of orpiment oxidation in the presence of albite and calcite show that calcite can act as an effective buffer to the acid water produced from orpiment oxidation within relatively short periods (days/months), but the release of As continues to increase.Pyrite oxidation rates are faster than orpiment and realgar from pH 2.3 to 8; however, pyrite oxidation rates are slower than As₂S₃ (am) and AsS (am) at pH 8. The activation energies of arsenic sulfide oxidation range from 16 to 124 kJ/mol at pH∼8 and temperature 25 to 40°C, and pyrite activation energies are ∼52 to 88 kJ/mol, depending on pH and temperature range. The magnitude of activation energies for both pyrite and arsenic sulfide solids indicates that the oxidation of these minerals is dominated by surface reactions, except for As₂S₃ (am). Low activation energies of As₂S₃ (am) indicate that diffusion may be rate controlling.Limestone is commonly mixed with sulfide minerals in a mining environment to prevent acid water formation. However, the oxidation rates of arsenic sulfides increase as solution pH rises and result in a greater release of As. Furthermore, the lifetimes of carbonate minerals (i.e., calcite, aragonite, and dolomite) are much shorter than those of arsenic sulfide and silicate minerals. Thus, within a geologic frame time, carbonate minerals may not be present to act as a pH buffer for acid mine waters. Additionally, the presence of silicate minerals such as pyroxenes (wollastonite, jadeite, and spodumene) and Ca-feldspars (labradorite, anorthite, and nepheline) may not be important for buffering acid solutions because these minerals dissolve faster than and have shorter lifetimes than sulfide minerals. However, other silicate minerals such as Na and K-feldspars (albite, sanidine, and microcline), quartz, pyroxenes (augite, enstatite, diopsite, and MnSiO₃) that have much longer lifetimes than arsenic sulfide minerals may be present in a system. The results of our modeling of arsenic sulfide mineral oxidation show that these minerals potentially can release significant concentrations of dissolved As to natural waters, and the factors and mechanisms involved in arsenic sulfide oxidation warrant further study.     

神木北部矿区防治水技术

介绍了大柳塔矿12404工作面通过母河沟时采取的综合防治水技术措施,使工作面安全通过了母河沟薄基岩富水区.这不仅提高了生产效益和资源回收率,而且对神东矿区类似条件下的煤层开采取得了宝贵的经验.     

Mineralogical components of some thermally decomposed lignite and lignite ash from the Ptolemais basin, Greece

Two samples of Pliocene lignites from the Ptolemais basin of Greece, one from the upper and one from the lower lignite seams, were heated and dried in air at 50°C intervals from 50 to 1200°C. The two lignite samples initially contained the same minerals, namely calcite, dolomite, quartz, kaolinite, illite, pyrite and gypsum, but in different proportions. The lignite sample from the upper lignite seam is rich in Fe₂O₃, CaO and SO₃, while that from the lower lignite seam is rich in SiO₂ and Al₂O₃.Hematite, periclase, melilites, calcium ferrite and brownmillerite are constituents of the 1200°C lignite ash from both samples. The heating conditions and the chemistry of the samples lowered the formation temperatures of brownmillerite, which appeared in both samples at 950°C. In the Fe₂O₃, CaO- and SO₃-rich sample, magnesioferrite is present from 850 to 1100°C and hematite appears at 300°C. In the SiO₂- and Al₂O₃-rich sample, magnesioferrite was not detected at any temperature and hematite appeared at 600°C.Anhydrite, which normally decomposes in air at 1638°C, is the main constituent at 1150°C, on heating the lignite sample that was rich in Fe₂O₃, CaO and SO₃. Anhydrite diminishes at 1200°C. In the SiO₂- and Al₂O₃-rich lignite sample, anhydrite is main constituent at 1100°C, but diminishes considerably at 1150°C and decomposes at 1200°C.     

Association of oil source algae in some Tertiary basins,northern Thailand

A coal petrographic study of sediments, including coals, oil shale, and oil source rocks, in the fossil fuel deposits of northern Thailand revealed changes in alginite associations. In the Lower part of these Tertiary deposits, especially in the Fang oilfield, alginite A (a Botryococcus sp.) was the only type of alga found. Later, the association of Botryococcus braunii, Pila algae, thick-walled alginite B, and temperate palynomorphs were recognized in many coalfields, as well as in the middle part of the deposits in the Fang Basin. Their ages were Late Oligocene (?) to Early Miocene. In the upper part of the fossil fuel deposits, alginite B is dominant in many basins, together with Botryococcus-related taxa such as Pila algae, Reinschia and fresh-water-dwelling ferns. In the Mae Sod Basins Reinschia was found to be dominant in the northern part, whereas lamaginite dominated in the south, showing different environmental conditions in different parts of the basin during deposition. These different associations indicate changes in depositional environments in northern Thailand, resulting from climatic and/or sea level changes during Tertiary time.     

中国北方高砷地下水分布特征及成因分析

本文分析了银川平原北部饮水型砷中毒分布、水文地质条件和水化学特征,并探讨了地下水中砷离子分布规律和富集环境。研究表明:高砷地下水区呈两个条带状分布于冲湖积平原,主要为埋藏深度小于40m的潜水,水化学环境呈弱碱还原环境,水化学类型主要为HCO3-Na·Ca,Cl·HCO3-Na,Cl·HCO3-Na·Ca型;最后对比分析了中国北方内蒙古平原、山西大同盆地、新疆、吉林西部高砷地下水分布和环境地质特征。     

A comparative evaluation of minerals and trace elements in the ashes from lignite, coal refuse, and biomass fired power plants

Coal being a limited source of energy, extraction of energy from other sources like lignite, coal-refuse, and biomass is being attempted worldwide. The minerals and inorganic elements present in fuel feeds pose different technological and environmental concerns. Lignite ash, refuse ash, and biomass ash collected from Indian power plants burning lignite, coal-refuse, and mustard stalk, respectively, were analyzed for physico-chemical characteristics and trace elements. The lignite ash has high SiO₂, CaO, MgO, Al₂O_3, and SO₃; the refuse ash has high SiO₂ and Fe₂O₃, but low SO₃; the biomass ash has high SiO₂ (but low Al₂O₃), and high CaO, MgO, K₂O, Na₂O, SO₃, and P₂O₅. A substantial presence of chloride (2.1%) was observed in the biomass ash. Quartz is the most abundant mineral species. Other minerals are mullite, hematite, gehlenite, anhydrite, and calcite in the lignite ash; orthoclase in the refuse ash; albite, sanidine, gehlenite, anhydrite, and calcite in the biomass ash. Ashes with high concentrations (> 100 mg/kg) of trace elements are: lignite ash (V < La < Mn < Cr < Ni < Nd < Ba < Ce, Zn < Sr); refuse ash (Cr < Ce < V < Rb < Mn < Sr, Zn < Ba); biomass ash (Cu < Zn < Ba, Sr). Based on Earth crust normalization, Co, Ni, As, Se, Mo, Zn, Pb, U, and REEs (except Pr and Er) are enriched in the lignite ash; molybdenum, Zn, Cs, Pb, Th, U, La, Ce, and Lu in the refuse ash; and Mo, Zn, Sr, Cs, Pb, and Lu in the biomass ash. Elements As, Zn, Mo, Ni, Pb, Rb, Cr, V, Ba, Sr, and REEs are correlated with Al, indicating the possibilities of their association with aluminum silicates minerals. Similarly, barium, Cs, Th, and U are correlated with iron oxides; molybdenum and Sr may also be associated with sulfates and chlorides. Due to the alkaline nature of these ashes, the high concentrations of As and Se in the lignite ash; molybdenum in the biomass ash; and Se in the refuse ash may pose environmental concerns.     

氢化物发生-原子荧光光谱法测定水中的砷

采用氢化物发生-原子荧光光谱法,对地下水、地表水、饮用水以及生活污水中的砷含量进行测定,对氢化物发生条件、载流酸类型、酸的浓度、还原掩蔽剂浓度等影响因素进行详细探讨,选出优化的测定条件:以5％的盐酸为载流酸性介质,以20 g·L-1的硼氢化钠(溶解于2 g·L-1的氢氧化钠稳定剂中)为还原剂,以50 g·L-1硫脲-抗...     

The sources of geogenic arsenic in aquifers at Datong basin,northern China: Constraints from isotopic and geochemical data

Mineralogical, geochemical and zircon U–Pb dating studies were carried out to identify the sources of arsenic in the shallow aquifers of Datong Basin in northern China. A sediment sample from 18 m depth containing 10.3 mg/kg arsenic showed a Zircon U–Pb concordant age of 2528 ± 20 to 271 ± 4 Ma that can be divided into two groups (2528 ± 20 to 1628 ± 21 Ma and 327 ± 4 to 271 ± 4 Ma) and is comparable to that of the sedimentary rocks of Taiyuan (upper Carboniferous) and Shanxi Formation (lower Permian) outcropping to the west of Datong Basin. In contrast, a sediment sample from 22.5 m depth containing 5.7 mg/kg arsenic displayed a Zircon U–Pb concordant age ranging from 2561 ± 21 to 1824 ± 26 Ma that is comparable to that of the Hengshan Complex (Ne-Archaean Precambrian) outcropping to the east of .     

Environmental impact assessment of open pit mining in Iran

Mining is widely regarded as having adverse effects on environment of both magnitude and diversity. Some of these effects include erosion, formation of sinkhole, biodiversity loss and contamination of groundwater by chemical from the mining process in general and open-pit mining in particular. As such, a repeatable process to evaluate these effects primarily aims to diminish them. This paper applies Folchi method to evaluate the impact of open-pit mining in four Iranian mines that lacked previous geo-environmental assessment. Having key geologic resources, these mines are: Mouteh gold mine, Gol-e-Gohar and Chogart iron mines, and Sarcheshmeh copper mine. The environmental components can be defined as public health and safety, social relationships, air and water quality, flora and fauna hence, various impacting factors from the mining activities were estimated for each environmental component. For this purpose, each impacting factor was first given a magnitude, based solely on the range of possible scenarios. Thereafter, a matrix of weighted factors was derived to systematically quantify and normalize the effects of each impacting factor. The overall impact upon each individual environmental component was then calculated by summing the weighted rates. Here, Folchi method was applied to evaluate those environmental conditions. Based on the acquired results, the present paper finally concludes that amongst four case histories in Iran, Sarcheshmeh copper mine significantly affects the environment, with critical level of air pollution there.     

松辽盆地北部热史恢复及烃源岩生烃史

根据镜质体反射率、粘土矿物分析和包裹体测试数据对松辽盆地北部齐家-古龙凹陷、三肇凹陷、黑鱼泡凹陷和双城向斜的古地温进行了研究并恢复了其热历史.它们都是在明水组沉积末期达到最高古地温,从古近纪到现今古地温持续降低.各个凹陷经历的古地温高低顺序依次为：古龙凹陷 >双城向斜 >三肇凹陷 >黑鱼泡凹陷,对应最高古地温为160℃至120℃不等.成烃史研究表明：松辽盆地中-浅层主力烃源岩青山口组-段泥岩随着嫩江组的快速沉积迅速进入生烃阶段,但各地所处成烃阶段不同;齐家-古龙凹陷烃源岩在嫩江组沉积初期进入生油门限,在嫩江组-明水组沉积期为快速生烃期,现为成熟-高熟阶段;双城向斜和三肇凹陷烃源岩在嫩江组沉积中期进入生油门限,于嫩江组-明水组沉积末期为快速生烃期,现为成熟阶段;黑鱼泡凹陷烃源岩在嫩江组沉积期末进入生油门限,于四方台组-明水组沉积期为快速生烃期,现为低熟-成熟阶段.