Hydrogeologic effects on the quality of water in the Oued Issen watershed, western Upper Atlas Mountains, Morocco

The study of spatial and temporal variations of some hydrochemical properties in the Oued Issen watershed, Morocco, has revealed their close relation to the area's lithologic and geologic characteristics and to variations in hydroclimatological cycles. High concentrations of sodium chloride are measured during flood periods, when the outcrops of the basin are leached by streams draining the rather dense hydrographic network. These variations depend also on the relative abundance of tributaries on both sides of the Oued, their respective contributions being hydrochemically very different: (1) northern-side tributaries, which mainly leach evaporitic terranes dating from the Late Triassic and Late Liassic periods and which are rich in gypsum and halite, increase the mineralization of the Oued Issen waters flowing toward the Abdelmoumen Dam; (2) the low salinity of water observed in the upstream portion of the watershed is due to dilution by waters from the southern-side tributaries, which are derived from snowmelt and the leaching of the high Paleozoic massif; (3) in the middle part of the basin, the increase in mineralization of the Oued Issen becomes substantial between the Abdelmoumen Dam and the Dkhila Dam, the next dam downstream, due to the absence of dilution by waters from the southern-side tributaries, which are sparse in this part of the basin. In addition, during flood periods, the outflow from the first dam is stopped. Thus, the main contribution of NaCl to the Oued is from the very salty Tirkou spring, which is situated downstream from the first dam. The geological characteristics of the basin have induced the development of high-salinity zones, which are particularly evident in the southwestern part of the basin in the vicinity of the confluence of the Oued Boulebaz with the Oued Issen. The discharge of very salty springs is controlled by faults that offset the formations that underlie the hydrographic network and degrade the quality of the Oued Issen. This water later recharges the unconfined aquifer along the Oued where it flows on the Oued Souss Plain. Received, July 1998/Revised, July 1999, September 1999/Accepted, November 1999     

A GIS mapping assessment of the suitability of the Oued Rmel aquifer for irrigation in the Zaghouan district (north-eastern Tunisia)

A total of twenty-three water samples were collected in winter 2013 to assess groundwater quality in the Oued Rmel aquifer in the Zaghouan governate in Tunisia. These samples were subject to in-field measurements of some physico-chemical parameters (temperature, pH, and salinity), and laboratory analysis of major elements. Several parameters were used to assess the quality of water destined for irrigation, including electrical conductivity (EC) and sodium adsorption ratio (SAR). As part of this work, GIS was used to study spatial distributions of SAR, EC, residual sodium carbonate, sodium percentage (%Na), Doneen’s permeability index, Kelly’s ratio, and magnesium hazard and, therefore, evaluated the water quality of Oued Rmel (good, fair, or poor) regarding irrigation. The major ions most abundantly found in the waters of Oued Rmel were in the following order: Na⁺?>?Ca²⁺?>?Mg²⁺?>?K⁺ and Cl^??>?SO₄^2??>?HCO₃. 56% of water samples from the Oued Rmel aquifer showed a low alkalinization risk, where SAR was lower than 10, 39% have a medium soil destabilization risks (10?<?SAR?<?18), and just 5% indicated high alkalinity hazards (SAR?>?26). Samples of water intended for irrigation showed a medium to high sodicity and alkalinization risk. It is expected that output may help in assessing the impacts of water quality of the Oued Rmel aquifer used for irrigation.     

Delineation of potential recharge area using a hybrid model,case of Djelfa Hadjia watershed

Groundwater potential map is important for environmental assessment and water resources management. In this work, a groundwater recharge potential map was established for the watershed of Oued Djelfa Hadjia in Algeria, based on new multiparameters hybrid model. The model has hydroclimatic parameters, geological settings, slope factor, and stream network density factor as inputs. The groundwater recharge estimated by the model range from 0.71 to 14 mm. The model allows delineation of potential area of recharge. The total water abstraction in Djelfa city is about of 14 hm³; however, the calculated groundwater recharge is about 3 mm/year (min 0.71 mm and max 14 mm), which correspond to an average recharge volume of 3.9 hm³ which mean that the aquifer is under over exploitation.     

Coastal erosion in the south-eastern Mediterranean: case of beaches in North Tunisia

This research is conducted as part of a Spanish International Cooperation Agency project with the aim to investigate the sustainable protection of Tunisian coastal zones, as in the case of Beni Khiar and Dar Chaabane coasts (Hammamet Gulf) separated by Oued El Kebir river. The sedimentary dynamic of these beaches is studied in order to identify the main causes responsible for their erosion by the use of different approaches of in situ measurements and numerical methods. Geophysical surveys and sedimentary analyses have demonstrated that sediments are finer and less carbonated from Beni Khiar to Dar Chaabane. Then, the shoreline mapping of several missions of aerial photos has illustrated a mean shoreline retreat between 3 and 4 m/year. In terms of sand volume, a sediment loss more than 30,000 m³/year at Dar Chaabane has been observed since the hill lake structures were built within Oued El Kebir river in 1996. Finally, modelled hydrodynamic and sedimentary patterns have illustrated the refraction of waves in deep water close to shoals and a high-energy concentration along Dar Chaabane coast. The sediment transport direction is mainly of NE-SW induced by ESE-SE wave-driven alongshore current. Results provided by these approaches have shown the importance of Oued El Kebir sediment yield in supplying the neighbouring beaches. Changes in sedimentary dynamics are affected by the modification of hydrodynamic patters caused by the presence of hydrological dams and the implementations of hotels close to the shoreline. This finding underlines the key role of Oued El Kebir fluvial activity in controlling the equilibrium of beaches and their sensitivity to coastal managements induced by man activities, as in the case of the most Mediterranean beaches.     

Distribution of Cu,Co, As,and Fe in mine waste,sediment, soil,and water in and around mineral deposits and mines of the Idaho Cobalt Belt,USA

The distribution of Cu, Co, As and Fe was studied downstream from mines and deposits in the Idaho Cobalt Belt (ICB), the largest Co resource in the USA. To evaluate potential contamination in ecosystems in the ICB, mine waste, stream sediment, soil, and water were collected and analyzed for Cu, Co, As and Fe in this area. Concentrations of Cu in mine waste and stream sediment collected proximal to mines in the ICB ranged from 390 to 19,000 μg/g, exceeding the USEPA target clean-up level and the probable effect concentration (PEC) for Cu of 149 μg/g in sediment; PEC is the concentration above which harmful effects are likely in sediment dwelling organisms. In addition concentrations of Cu in mine runoff and stream water collected proximal to mines were highly elevated in the ICB and exceeded the USEPA chronic criterion for aquatic organisms of 6.3 μg/L (at a water hardness of 50 mg/L) and an LC50 concentration for rainbow trout of 14 μg/L for Cu in water. Concentrations of Co in mine waste and stream sediment collected proximal to mines varied from 14 to 7400 μg/g and were highly elevated above regional background concentrations, and generally exceeded the USEPA target clean-up level of 80 μg/g for Co in sediment. Concentrations of Co in water were as high as in 75,000 μg/L in the ICB, exceeding an LC50 of 346 μg/L for rainbow trout for Co in water by as much as two orders of magnitude, likely indicating an adverse effect on trout. Mine waste and stream sediment collected in the ICB also contained highly elevated As concentrations that varied from 26 to 17,000 μg/g, most of which exceeded the PEC of 33 μg/g and the USEPA target clean-up level of 35 μg/g for As in sediment. Conversely, most water samples had As concentrations that were below the 150 μg/L chronic criterion for protection of aquatic organisms and the USEPA target clean-up level of 14 μg/L. There is abundant Fe oxide in streams in the ICB and several samples of mine runoff and stream water exceeded the chronic criterion for protection of aquatic organisms of 1000 μg/L for Fe. There has been extensive remediation of mined areas in the ICB, but because some mine waste remaining in the area contains highly elevated Cu, Co, As and Fe, inhalation or ingestion of mine waste particulates may lead to human exposure to these elements.     

Age and depositional environment of the Draa Sfar massive sulfide deposit, Morocco

The Draa Sfar mineralization consists of two main stratabound orebodies, Sidi M’Barek and Tazacourt, located north and south of the Tensift River (“Oued Tessift”), respectively. Each orebody is comprised by at least two massive sulfide lenses. The hosting rocks are predominantly black shales, although minor rhyolitic rocks are also present in the footwall to the southern orebody. Shales, rhyolitic volcanic rocks, and massive sulfides are all included into the Sarhlef Series, which is recognized as one of the main stratigraphic units of the Moroccan Variscan Meseta. Hydrothermal activity related with an anomalous thermal gradient, together with a high sedimentation rate in a tectonically driven pull-apart marine basin, favored the accumulation of organic-rich mud in the deepest parts of the basin and the sedimentary environment suitable for massive sulfide deposition and preservation. This took place by replacement of the hosting unlithified wet mud below the sediment–water interface. Geochemical data suggest a sedimentary environment characterized by oxic water column and anoxic sediment pile with the redox boundary below the sediment–water interface. The low oxygen availability within the sediment pile inhibited oxidation and pyritization of pyrrhotite. Biostratigraphic analysis, based on the palynological content of the hosting black shales, restricts the age of the sulfides to the Asbian substage (mid-Mississippian). This age is consistent with earlier geochronological constraints.     

Assessment of organic pollutants (PAH and PCB) in surface water: sediments and shallow groundwater of Grombalia watershed in northeast of Tunisia

Toxic organic compounds in wastewater are serious threats for both human and environment healthy states. This study investigates the potential sources of surface water, sediment and groundwater pollution by polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyl (PCBs) as discharged by wastewater into the River of Oued El bey in northeastern Tunisia. Analysis indicates that the concentration of PAHs and PCBs are high in wastewater and vary from 0.37 to 0.83 mg/L and from 0.28 and 1.18 mg/L, respectively. The spatial distribution of PAHs and PCB in surface water showed a variation between 0.37 to 9.91 mg/L and between 0.1 to 0.47 mg/L, respectively. However, the quality of surface water is changed after wastewater evacuation at Oued Tahouna. The determination of PAH and PCB pollutants in groundwater shows a great interest in the development of water resources. The Concentration of these pollutants varying from 0.0204 to 1.93 mg/L and from 0.0052 to 0.196 mg/L, respectively. For PAH, analysis reveals also that naphtelene, fluorene, anthracene and chrysene are the most detected PAHs compounds in water and sediment samples while benzo[b]fluoranthene and benzo[a]pyrene are less present and in trace level. Higher concentrations of PAHs and PCBs are found in samples taken close to industrial areas of Bouargoub and Soliman, and wastewater discharge locations in Soliman. Analysis of the spatial distribution of PAHs and PCBs clearly link their higher concentration in water and sediments to wastewater and manufacturing discharges in the study area. In surface sediment, the organic pollutants are present. The cluster analysis for organic pollutants in different state and different matrix highlight a relationship between the wastewater evacuation and the water qualities which confirmed the direct response of the pollution sources on the surface water and groundwater organic pollution quality.     

The earthquake swarm of December 2007 in the Mila region of northeastern Algeria

In December 2007, the Mila region of northeastern Algeria experienced thousands of microearthquakes (0.8????Md????3.9) recorded by eight temporary stations, in addition to permanent stations. Most of the events were too small to be located precisely, but a set of 122 precisely located events shows an alignment of epicenters, extending mainly in a horizontal band at about 1?C2?km depth in a NNW?CSSE direction and concentrated in a small area, 3?km southeast of Jebel Akhal, a small rocky hill between the Beni Haroun dam/reservoir and the Oued Athmania reservoir. The reservoirs are connected by pipelines, and a pumping station ensures water can be transferred between them at transient pressures of up to 80?bars. During the pumping in 2007, only 45?% of the transferred water (~600,000?m³ per day) was recovered at the Oued Athmania reservoir, and a large amount of the slightly pressurized water leaked through defective joints in a tunnel that passes through the Jebel. This water penetrated deeply into the soil with the assistance of preexisting fractures, faults, and karsts. Nine days after the first pumping started, a local increase in pore fluid pressures at shallow depths triggered seismicity southeast of Jebel Akhal, where the faults were probably close to failure. The focal mechanisms show a near vertical N?CS strike-slip fault plane under regional NW?CSE tectonic compression. One of the fault plane solutions is consistent with the NNW?CSSE direction along which the seismic events are aligned. Furthermore, a long-term comparison of the seismic activity in the region versus water levels behind the dam and the pumping of water shows that the earthquake swarm was a one-off event related to the pumping operation.     

Assessment of environmental hazards at abandoned mining sites: A case study in Sardinia,Italy

In the last two centuries, several Pb–Zn mines were active in the Rio Mannu basin near Narcao (SW Sardinia, Italy), but are now abandoned. These abandoned mines pose a serious risk to the population and required an assessment of the hazard sources and the contaminant pathways in the area. The characterization plan of the Rio Mannu basin was carried out according to Italian protocols. Specifically, samples of soil, stream sediment, fine-grained ore-processing waste (from washery and flotation processes), surface water and groundwater have been analyzed in order to assess the levels of contamination in each mine area and the risks in the plains surrounding the site. Several potential chemical contaminants were considered both in solid materials and water samples. The Rosas mine was recognized as the most contaminated area in the basin, due to the presence of a large tailing pond, some fine-grained waste piles and two mine adits with concentrations of the toxic elements As, Cd, Cu, Pb, Sb and Zn exceeding Italian regulatory standards. The dispersion of contaminants occurs downstream from the small stream draining the area. In case of heavy rain the runoff into the streamlet transports the contaminated material far into the plain. The results of this study show that the characterization plan is a relatively cheap tool for establishing mitigation actions, prior to the realization of a complete, and usually expensive, remediation project at abandoned mine sites. Urgent recommended actions in the Rio Mannu basin include the treatment of the adit water prior to its discharge into the Rio Barisonis; the construction of drainage barriers on waste piles to reduce runoff and solid transport into the Rio Barisonis; the consolidation of the earthen dam containing the tailing pond of Rosas to avoid the deepening of erosion furrows that may threaten its stability.     

我国露天煤矿截水帷幕关键技术进展

我国露天煤矿普遍采用抽排方式进行地下水控制以满足煤炭资源安全开采要求,这种方式对水资源造成极大破坏,严重影响煤矿周边的生态环境。近年来,随着我国社会经济的全面发展,国家对生态环境保护、生态文明建设提出了更高要求,如何优化、转变露天煤矿地下水控制方式,减少矿坑疏排水量是露天煤矿防治水工作普遍面临的崭新课题。采用截水帷幕技术取代疏排降水技术,由被动疏水变为主动截水,是解决露天煤矿因疏排水带来诸多问题的根本措施。以内蒙古扎尼河露天煤矿、元宝山露天煤矿截水帷幕实施过程为例,介绍我国露天煤矿截水帷幕设计理念、施工工艺和截水帷幕材料,在实践过程中,突破了防渗膜大深度垂向隐蔽铺设与连接技术瓶颈;研发了超长槽段连续开挖及浇筑工艺,大幅减少接头数量;研制粉煤灰?水泥混合浆体与HDPE防渗膜的复合帷幕材料,提高帷幕抗渗与抗变形性能;构建帷幕质量与截水效果综合检验体系,掌握了露天煤矿截水帷幕建造关键技术。截水帷幕技术在我国露天煤矿的成功应用,丰富了露天煤矿防治水与水资源保护技术理论,促进了行业技术进步,为露天煤矿地下水控制及安全绿色开采提供了新思路、新技术、新工艺,对其他非煤矿山及水利水电、交通等更高防渗等级要求的工程具有重要借鉴意义。      

Water quality impacts from mining in the Black Hills,South Dakota,USA

The focus of this research was to determine if abandoned mines constitute a major environmental hazard in the Black Hills. Many abandoned gold mines in the Black Hills contribute acid and heavy metals to streams. In some areas of sulfide mineralization local impacts are severe, but in most areas the impacts are small because most ore deposits consist of small quartz veins with few sulfides. Pegmatite mines appear to have negligible effects on water due to the insoluble nature of pegmatite minerals. Uranium mines in the southern Black Hills contribute some radioactivity to surface water, but the impact is limited because of the dry climate and lack of runoff in that area.     

The chemistry of bottled mineral and spring waters from Norway,Sweden, Finland and Iceland

Twenty-two bottled mineral and spring waters from Norway, Sweden, Finland and Iceland have been analysed for 71 inorganic chemical parameters with low detection limits as a subset of a large European survey of bottled groundwater chemistry (N = 884). The Nordic bottled groundwaters comprise mainly Ca–Na–HCO₃–Cl water types, but more distinct Ca–HCO₃, Na HCO₃ and Na–Cl water types are also offered. The distributions for most elements fall between groundwater from Fennoscandian Quaternary unconsolidated aquifers and groundwater from Norwegian crystalline bedrock boreholes. Treated tap waters have slightly lower median values for many parameters, but elements associated with plumbing have significantly higher concentrations in tap waters than in bottled waters. The small dataset is able to show that excessive fluoride and uranium contents are potential drinking water problems in Fennoscandia. Nitrate and arsenic displayed low to moderate concentrations, but the number of samples from Finland and Northern Sweden was too low to detect that elevated concentrations of arsenic occur in bedrock boreholes in some regions. The data shows clearly that water sold in plastic bottles is contaminated with antimony. Antimony is toxic and suspected to be carcinogenic, but the levels are well below the EU drinking water limit. The study does not provide any health-based arguments for buying bottled mineral and spring waters for those who are served with drinking water from public waterworks. Drinking water from crystalline bedrock aquifers should be analysed. In case of elevated concentrations of fluoride, uranium or arsenic, most bottled waters, but not all, will be better alternatives when treatment of the well water is not practicable.     

Mercury distribution in coals influenced by magmatic intrusions,and surface waters from the Huaibei Coal Mining District,Anhui, China

The Hg concentrations in 108 samples, comprising 81 coal samples, 1 igneous rock, 2 parting rock samples and 24 water samples from the Huaibei Coal Mining District, China, were determined by cold-vapor atomic fluorescence spectrometry. The abundance and distribution of Hg in different coal mines and coal seams were studied. The weighted average Hg concentration for all coal samples in the Huaibei Coalfield is 0.42 mg/kg, which is about twice that of average Chinese coals. From southwestern to northeastern coalfield, Hg concentration shows a decreasing trend, which is presumably related to magmatic activity and fault structures. The relatively high Hg levels are observed in coal seams Nos. 6, 7 and 10 in the southwestern coal mines. Correlation analysis indicates that Hg in the southwestern and southernmost coals with high Hg concentrations is associated with pyrite. The Hg concentrations in surface waters in the Huaibei Coal Mining District range from 10 to 60 ng/L, and display a decreasing trend with distance from a coal waste pile but are lower than the regulated levels for Hg in drinking water.     

Mineralogy and microstructures of carbonaceous gold ores

Summary This paper describes mineralogical and geological aspects of the Owl Creek and Hoyle Pond gold mines, located in Archean metasediments and metavolcanics in the Abitibi greenstone belt in northern Ontario, Canada. The occurrence of invisible gold of Cenozoic age, hosted in structurally-controlled settings in Paleozoic strata of the southwestern U.S.A., has been known and exploited for over thirty years. Petrographic observations are combined with electron microprobe data in order to describe aspects of gold mineralization from these Ontario mines and from selected analogous sites elsewhere. Details of selected exposures of Archean-Proterozoic lithologies, which are carbonaceous but not strongly enriched in gold, are briefly compared with features of the mine geology. Although no mine generates carbonaceous ores alone, the proportion of such ores varies widely from mine to mine, and district to district. Questions remain, particularly with regard to the chemical behaviour of the reduced carbon, but two common factors of prime economic relevance are established. These are the importance of (a) fluid focusing through incompetent carbonaceous units, and (b) localization of high (commonly visible) gold values on vein-wallrock contacts.

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La Minéralogie et micro-structures des minerais carbonifères d'or

Résumé Ce compte rendu s'intéresse au gîtes carbonifères d'or, spécialement dans la ceinture de roches vertes de l'Abitibi au nord de l'Ontario, au Canada. Des observations pétrographiques sont combinées avec des analyses de microsonde électronique afin de décrire quelques aspects de la minéralogie et de la géologie des mines d'or; en particulier Owl Creek et Hoyle Pond, et aussi des emplacements dont la concentration en or est trop faible pour être exploité. Trois générations de pyrite sont observée à Owl Creek, la troisième contenant de l'or. Souvent l'or est situé entre la veine de quartz et l'encaissante carbonifère, fréquemment avec de l'hydromicas sodiques, de la chlorite ferrifère et de la tourmaline. Cette association dont l'importance économique est substantielle, est produite par la concentration de fluides hydrothermales à travers des rocs carbonifères friables.

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With 6 Figures

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Contribution to the Ore Mineralogy Symposium (IMA/COM)at the 14th General Meeting of the International Mineralogical Association, at Stanford, California, in July, 1986.     

Environmental impact of the abandoned coal mines on the surface water and the groundwater quality in the south of Bochum,Germany

Surface water and groundwater samples were collected from 20 locations, situated in the vicinity of the abandoned coal mine fields south of Bochum. The main objective of this research is to assess the environmental impacts of these mines on the surface water and groundwater quality as well as to determine the factors controlling these impacts. The water samples were collected from stream sources, groundwater, surface water and engineered channels during April 2011. Physicochemical parameters were measured during fieldwork. Water samples were analysed for major ions and aluminium, iron, manganese, ferrous iron, zinc and hydrogen sulphide. The hydrochemistry of the surface water and the groundwater of this area is characterized by near-neutral to alkaline conditions, represented by predominance of calcium bicarbonate and sometimes calcium sulphate water types. Hence, the surface water and the groundwater quality in this region is significantly affected by abandoned coal mines. These effects resulted from oxidation of iron disulphide minerals that release iron, sulphate and hydrogen. The presence of carbonate-rich materials, which contained within the landfilling materials, has led the releasing of calcium, magnesium and bicarbonate. These materials could be the main source responsible for raising the alkalinity of the affected water. The environmental hazard of the abandoned coal mines in this area is related to the high concentration of Fe especially in the groundwater that possess the highest Fe concentration compared to other water sources: the Fe is 18 times larger than the allowed value in drinking water. Significant spatial variations of the water pollution were noted in this study. For this reason, the environmental hazards of the abandoned coal mines in Germany should be considered at closure of coal mines in the near future. Otherwise, these mines will be sources of environmental threats unless all necessary measures are taken to reduce their impact.     

Mineralogy and environmental geochemistry of historical iron slag,Hopewell Furnace National Historic Site,Pennsylvania, USA

The Hopewell Furnace National Historic Site in southeastern Pennsylvania, which features an Fe smelter that was operational in the 18th and 19th centuries, is dominated by three slag piles. Pile 1 slag, from the Hopewell Furnace, and pile 2 slag, likely from the nearby Cornwall Furnace, were both produced in cold-blast charcoal-fired smelters. In contrast, pile 3 slag was produced in an anthracite furnace. Ore samples from the nearby Jones and Hopewell mines that fed the smelter are mainly magnetite-rich with some sulfides (pyrite, chalcopyrite, sphalerite) and accessory silicates (quartz, garnet, feldspar, and clay minerals). Slag piles 1 and 2 are similar mineralogically containing predominantly skeletal and dendritic aluminian diopside and augite, skeletal forsteritic olivine, glass, rounded blebs of metallic Fe, and exotic quartz. Olivine is a major phase in all samples from pile 2, whereas it occurs in only a few samples from pile 1. Samples of the <2 mm-size fraction of surface composite slag material or crushed slag from at depth in piles 1 and 2 are mineralogically similar to the large surface slag fragments from those piles with the addition of phases such as feldspars, Fe oxides, and clay minerals that are either secondary weathering products or entrained from the underlying bedrock. Pile 3 slag contains mostly skeletal forsteritic olivine and Ti-bearing aluminian diopside, dendritic or fine-grained subhedral melilite, glass, euhedral spinel, metallic Fe, alabandite–oldhamite solid solution, as well as a sparse Ti carbonitride phase. The bulk chemistry of the slag is dominated by Al₂O₃ (8.5–16.2 wt.%), CaO (8.2–26.2 wt.%), MgO (4.2–24.7 wt.%), and SiO₂ (36.4–59.8 wt.%), constituting between 81% and 97% of the mass of the samples. Piles 1 and 2 are chemically similar; pile 1 slag overall contains the highest Fe₂O₃, K₂O and MnO, and the lowest MgO concentrations. Pile 3 slag is high in Al₂O₃, CaO and S, and low in Fe₂O₃, K₂O and SiO₂ compared to the other piles. In general, piles 1 and 2 are chemically similar to each other, whereas pile 3 is distinct – a conclusion that reflects their mineralogy. The similarities and differences among piles in terms of mineralogy and major element chemistry result from the different smelting conditions under which the slag formed and include the fuel source, the composition of the ore and flux, the type of blast (cold versus hot), which affects the furnace temperature, and other beneficiation methods.     

Management of karst water resources in mining area: dewatering in mines and demand for water supply in the Dongshan Mine of Taiyuan, Shanxi Province, North China

Coalfields in North China contain six to seven coal seams in the Permo-Carboniferous strata. The coal seams are underlain by the Ordovician limestone. Large-scale dewatering or depressurizing of the karst aquifer was considered essential to avoid water inrushes and keep the mines safely operational. This practice, however, has caused water supply shortage in the mining areas. The most effective solution to this conflict is to use the uncontaminated karst water from the mines for water supply. This paper explores a management model to maximize the utilization of the karst water while maintaining the safe operation of the mines. The model can provide essential information on water resource distribution for decision makers. The model was applied to the Dongshan Coal Mine in Taiyuan City, China.     

Technologies of Preventing Coal Mine Water Hazards for Sustainable Development in North China

As hydrogeological conditions of coal field in North China are complicated, coal mine water hazards have been occurring frequently. Nearly 80% of coal mines are affected by Ordovician and Permo-Carboniferous Karst water. According to rough statistics, 200 incidents of water inrush have occurred since 1950, 1,500 persons have died, and there is an economic loss of 3 billion Yuan (RMB). The climate of North China belongs to drought or semi-drought zone. So the recharge amount of ground water by infiltration of precipitation is limited. Stronger coal mine water drainage has brought a series of environmental problems, such as water resource and lots of famous Karst springs exhausted, surface collapse emerged, mine water contaminated. Coal mine water hazards are so serious that the economic benefit of coal mines is dropping. Sustainable development of coal mines is affected. So, preventing coal mine water hazards and protecting geological environment are essential. This thesis focuses on preventing coal mine water hazards technologies. The technologies include four aspects: exploration of hydrogeological conditions; prediction and forecast of water inrush; mining under safe water pressure; and sealing off groundwater by grouting.