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1.
The Great Falls-Lewistown Coal Field (GFLCF) in central Montana contains over 400 abandoned underground coal mines, many of which are discharging acidic water with serious environmental consequences. Areas of the mines that are completely submerged by groundwater have circum-neutral pH and relatively low concentrations of metals, whereas areas that are only partially flooded or freely draining have acidic pH (< 3) and high concentrations of metals. The pH of the mine drains either decreases or increases after discharging to the surface, depending on the initial ratio of acidity (mainly Al and Fe2+) to alkalinity (mainly HCO3?). In acidic, Fe-rich waters, oxidation of Fe2+ after exposure to air is microbially catalyzed and follows zero-order kinetics, with computed rate constants falling in the range of 0.97 to 1.25 mmol L? 1 h? 1. In contrast, Fe2+ oxidation in near-neutral pH waters appears to be first-order with respect to Fe2+ concentration, although insufficient data were collected to constrain the rate law expression. Rates of Fe2+ oxidation in the field are dependent on temperature such that lower Fe2+ concentrations were measured in down-gradient waters during the day, and higher concentrations at night. Diel cycles in dissolved concentrations of Zn and other trace metals (Mn, Ni) were also noted for down-gradient waters that were net alkaline, but not in the acidic drains.The coal seams of the GFLCF and overlying Cretaceous sandstones form a perched aquifer that lies ~ 50 m above the regional water table situated in the underlying Madison Limestone. The δD and δ18O values of flooded mine waters suggest local derivation from meteoric water that has been partially evaporated in agricultural soils overlying the coal mines. The S and O isotopic composition of dissolved sulfate in the low pH mine drains is consistent with oxidation of biogenic pyrite in coal under aerated conditions. A clear distinction exists between the isotopic composition of sulfate in the acid mine waters and sulfate in the adjacent sedimentary aquifers, making it theoretically possible to determine if acid drainage from the coal mines has leaked into the underlying Madison aquifer.  相似文献   

2.
 Acid mine drainage (AMD) from abandoned underground mines significantly impairs water quality in the Jones Branch watershed in McCreary Co., Kentucky, USA. A 1022-m2 surface-flow wetland was constructed in 1989 to reduce the AMD effects, however, the system failed after six months due to insufficient utilization of the treatment area, inadequate alkalinity production and metal overloading. In an attempt to improve treatment efficiencies, a renovation project was designed incorporating two anoxic limestone drains (ALDs) and a series of anaerobic subsurface drains that promote vertical flow of mine water through a successive alkalinity producing system (SAPS) of limestone beds overlain by organic compost. Analytical results from the 19-month post-renovation period are very encouraging. Mean iron concentrations have decreased from 787 to 39 mg l–1, pH increased from 3.38 to 6.46 and acidity has been reduced from 2244 to 199 mg l–1 (CaCO3 equivalent). Mass removal rates averaged 98% for Al, 95% for Fe, 94% for acidity, 55% for sulfate and 49% for Mn during the study period. The results indicate that increased alkalinity production from limestone dissolution and longer residence time have contributed to sufficient buffering and metal retention. The combination of ALDs and SAPS technologies used in the renovation and the sequence in which they were implemented within the wetland system proved to be an adequate and very promising design for the treatment of this and other sources of high metal load AMD. Received: 29 June 1998 · Accepted: 15 September 1998  相似文献   

3.
以美国匹兹堡煤田为例,介绍了废弃矿井地下水回充、相邻矿井水连通和自流排泄出地表,以致造成河水污染,生产矿井涌水量增加,甚至导致生产矿井水害事故等问题。强调应基于GIS和GPS等技术对这类矿区进行水文地质填图,设立长期水位水质观测站,并有针对性的设置矿井水处理厂。针对我国废弃矿井充水问题提出了建议。   相似文献   

4.
Natural recharge due to rainfall (annual average 1,200 mm) over an area of 1,500 km2 of the Neyveli groundwater basin was carried out for two consecutive hydrological years, using the tritium injection technique. The lignite seams, occurring within the Upper Miocene formation in the basin have been mined for the last 40 years. The confined aquifer underlying the lignite seams has been pumped continuously since 1961, for depressurization and safety around the mine. The recharge zone is identified as an elongated zone, oriented in a NE–SW direction within the basin. Natural recharge measurements were made at several sites (single and duplicate injections), covering the entire basin. They indicate a recharge rate of 333–556 mm/year (24–40% of rainfall) in the north and northeastern parts, covering the previously defined recharge areas as well as some adjoining areas. Soil moisture movement at several duplicate sites in these areas showed significant downward migration of tracer during the non-monsoon period, probably caused by pumping in the mine area. Isotopic data of ground water samples in the northern and northeastern part of the basin indicates modern ages. Concurrent field observations like deep water table with high annual fluctuations and exposure of pebble beds, enabled the redemarcation of the aggregate recharge area as 650 km2. The redefined recharge area includes the areas identified by earlier workers as well as the new area on the northeastern side of the lignite mine.  相似文献   

5.
Summary  Abandoned gypsum and anhydrite mines can be filled by underground water that progressively dissolves pillar rock. The long term stability of the mine under the weight of the overburden is therefore jeopardised. A common remedial measure consists in filling the flooded chambers with granular materials. The aim of the paper is that of investigating the effect of the mechanical characteristics of the filler on the time of mine collapse, induced subsidence and pore water pressure generation. By means of Sharp Front theory the saturation front advance and the loss of pillar bearing capacity with time is determined first. Subsequently one dimensional consolidation theory is used for the determination of the proportion of overburden weight carried by the solid skeleton of the filler and by water pressure. A parametric analysis is eventually performed for the case of an abandoned gypsum and anhydrite mine in order to determine the most appropriate mechanical characteristics of the filler material. Author’s address: Eleni Gerolymatou, Department of Applied Mathematics and Physics, National Technical University of Athens, 9 Iroon Politechneiou Street, 15780 Athens, Greece  相似文献   

6.
主要从水文地球化学的角度,以鄂尔多斯盆地白于山以南地区白垩系地下水的水化学水平分带和地表水基流水化学特征为主要依据,结合地质构造格局及岩相古地理条件,分析研究了该区白垩系地下水的补、径、排条件。认为该区白垩系地下水水化学场存在一个由东、北、西南向中部的水平分带,愈向盆地中部水质愈复杂、TDS愈高。马莲河基流水质的沿途变化规律反映出其接受东西两侧地下水的补给。说明鄂尔多斯盆地南区的东部地区和西南部地区为地下水补给区,而中心地带为地下水排泄区,最终经马莲河排出区外。天环向斜轴部和马莲河谷是南区汇集东西两侧地下水的排泄通道。  相似文献   

7.
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.  相似文献   

8.
本文以鹤岗煤田峻德、兴安两矿为例,作为典型的傍河型孔隙、裂隙充水矿床,对其矿床充水条件和充水来源组成进行了分析,确定鹤立河水侧向补给是矿井涌水的主要来源;通过多年矿井涌水量、补给组成及保障分析,得到其矿井涌水具备充足的补给来源、矿井水资源化具有较大可行性的结论,为此类矿床的研究提供了借鉴和参考。  相似文献   

9.
The Rozna Mine is one of the last active uranium mines in Europe. When the mine is closed and flooded, the natural groundwater flow pattern will be partly restored. Re-established groundwater flow system will be associated with an increase of groundwater discharge into draining rivers and streams. Since the groundwater inflows to streams can be contaminated by the mine water, the groundwater drainage characteristic of fractured aquifer should be carefully identified. Several methods of groundwater discharge zones identification were used including morphological analysis, thermometry, and electrical conductivity (EC) measurements. Stream temperatures and EC at more than 700 points in the area covering about 85 km2 were measured. The measurements were performed during winter period, when stream discharges were low and there was a maximum temperature contrast. There was a frequent presence of preferential discharge zones with resulting anomalous temperatures and electric conductivity values of stream water. The results show evident correlation of discharge zones with surface morphology and geological settings. Just like the aquifer discharge characteristics, the aquifer is strongly heterogeneous. The thermometry supported by measurement of EC proved to be a useful tool for large-scale investigation of groundwater flow and drainage in fractured aquifers.  相似文献   

10.
 Aquifers above high-extraction underground coal mines are not affected by mine drainage, but they may still exhibit changes in groundwater chemistry due to alterations in groundwater flow induced by mine subsidence. At two active longwall mine sites in Illinois, USA, glacial-drift aquifers were largely unaffected by mining, but the geochemistry of the bedrock aquifers changed during the post-mining water-level recovery. At the Jefferson site, brackish, high-sulfate water present in the upper bedrock shale briefly had lower values of total dissolved solids (TDS) after mining due to increased recharge from the overlying drift, whereas TDS and sulfate increased in the sodium-bicarbonate water present in the underlying sandstone due to downward leakage from the shale and lateral inflow of water through the sandstone. At the Saline site, sandstones contained water ranging from brackish sodium-chloride to fresh sodium-bicarbonate type. Post-mining recovery of the potentiometric levels was minimal, and the water had minor quality changes. Longwall mining affects geochemistry due to subsidence-related fracturing, which increases downward leakage from overlying units, and due to the temporary potentiometric depression and subsequent recovery, whereby water from surrounding areas of the aquifer recharges the affected zone above and adjacent to the mine. Received, December 1998 / Revised, August 1999 / Accepted, August 1999  相似文献   

11.
Managing mine water that has been contaminated with metal sulfide minerals due to galvanic corrosion is becoming an increasingly important environmental problem. Here, galvanic corrosion was investigated by studying galvanic interactions between pyrite–chalcopyrite and pyrite–galena in flowing mediums such as mine discharge water and flowing rainwater. The results showed that the corrosion current density of pyrite–galena is greater than that of pyrite–chalcopyrite under identical conditions. The corrosion current density of the galvanic cell tends to increase with increasing concentrations of strongly oxidizing ions (e.g., Fe3+) in the flowing medium, whereas the existence of non-oxidizing and non-reducing ions (e.g., Na+) have no obvious influence on the galvanic cell. In addition, the corrosion current density increases with increasing flow rate. Using the galvanic model, mixed potential theory and Butler–Volmer equation, the experimental results were explained theoretically. Because these experiments were performed under conditions very similar to those seen in mine discharge water and flowing rainwater, these results have direct implications for the future management and control of environmental pollution from mining operations.  相似文献   

12.
务川自治县大竹园铝土矿区为高山台地向斜正地形,岩溶充水矿床,水位埋藏较深,大气降水是地下水的唯一补给源,北、东、西为陡崖或陡坡,崖脚为矿系和隔水层,沿陡崖上部边缘分布一条开口向西的地表分水岭,形成完整的水文地质单元,地下水在向斜内由东向西汇集于梅古洞排泄。铝土矿层直接顶板梁山组(P_2l)页岩,厚度小,不连续,其上部茅口栖霞组(P_2m+q)灰岩强含水层与矿层直接接触,并且岩溶管道发育。因此,计算矿坑涌水量的方法用水均衡法较为恰当,即利用泉水观测资料计算入渗系数,从而达到预测矿坑涌水量、评价含水层富水性的目的。  相似文献   

13.
The present study deals with the hydrochemical characteristics of groundwater in the upper catchment of Wadi Fatimah basin. The analysis of data indicated strongly that the chloride and sulfate in the groundwater are mainly of marine origin, concentrated by high evaporation processes. Flushing is the most important factor that modifies the ionic concentrations and almost stands for the short-term variation in groundwater chemistry. Weathering reactions of the rock-forming minerals take place under relatively high PCO2 condition in water and soil zone; it can be an important long-term neutralization process. It is accounted as a contributor for Ca and Mg ions in the groundwater. Using the chloride method the recharge rate has been estimated at 72 mm yr–1.  相似文献   

14.
A field study was undertaken on the Florida Bay side of Fiesta Key, Florida, to identify the chemical characteristics of a previously unexplored offshore groundwater system and to define the critical parameters affecting groundwater movement and interaction with sediment pore fluids and bedrock. Emphasis was placed on the upper 2 meters of bedrock, where groundwater recharge and discharge potentials are maximized, along a 100 meter transect extending from the island margin. Bedrock cores were used to describe Pleistocene depositional textures, and were sampled at discrete depths to determine the extent of water-rock interaction. Piezometers installed into each core hole were used to monitor surface and ground water tide levels, and for the systematic collection of water samples for a large suite of chemical determinations.Aqueous chemical data indicate that these groundwaters are marine in origin, anoxic, and moderately hypersaline (S = 36–40). Exchange of bedrock pore fluids with overlying Bay waters is restricted by a layer of Holocene sediment and a discontinuous soilstone crust formed at the modern bedrock surface. Groundwater chemistry near the sediment/bedrock interface is marked by elevated concentrations of total alkalinity and Ca2+, and by significant Mg2+ depletion. These waters likely acquired their unusual chemistry by mixing between deeper groundwaters and overlying, early diagenetically altered, sediment porewaters. High alkalinity and calcium concentrations presumably result from the combination of the effects of aerobic metabolism, carbonate dissolution, and sulfate reduction. Mg-depletion most likely resulted from the precipitation of Mg-calcite. These unusual chemistries disappear by 2 m depth in the groundwater system, where Ca2+ and Mg2+ concentrations are similar to those expected for seawater under slightly hypersaline conditions.The Pleistocene bedrock contains low Mg, Sr, F, and P concentrations relative to the overlying unconsolidated Holocene carbonate sediments. This is consistent with the diagenetic recrystallization processes that the bedrock has undergone. Hydraulic conditions favor the net recharge of Florida Bay seawater to the groundwater system, but there are insufficient tide data to identify cyclical water exchange rates or groundwater flow patterns.  相似文献   

15.
Nitrogen budget of a typical subterranean river in peak cluster karst area   总被引：2，自引：0，他引：2  
Karst groundwater is one of the important water resources for people in the world. There is an estimate that by 2028 karst groundwater will supply more than 80% of people in the world. However, several areas in the world are characterized by high nitrate concentrations in karst aquifers. In China, karst groundwater is also threatened by extensive use of fertilizer and pesticides, industry waste, septic systems and poultry, hog or cattle manure. In order to understand the water quality of a subterranean river in south China, especially the dynamic variation of nitrate, nitrogen input and output were determined via auto-monitored apparatus, manual observation and samples from 2004 to 2008 in Guancun subterranean river drainage area. Land use and anthropogenic activities were also investigated frequently. The results showed the range of nitrate variation was 2.56–15.40 mg l−1, with an average value of 6.60 mg l−1. Spatial variation of nitrate concentrations showed nitrate rose where there were villages and agriculture distribution. Long series of nitrate and discharge monitoring revealed there was a nitrate peak in spring just before the beginning of rainy season. Three rainfall events were selected for analysis of relations among hydrological process, water chemistry, and nitrate of the spring. The flood processes of the spring were divided into three or four phases according to change of water level and water chemistry. They were dominated by initial condition of aquifer, piston flow in soil and vadose, piston flow in conduit, diffuse recharge, and bypass recharge. The original condition of aquifer and rainfall pulse controlled recharge flow and changes of nitrate and hydro-chemical graphs of the spring. The quantity of nitrogen input in a year was 66.61 t, and the output was 21.24 t. Nitrogen leaching loss in base flow accounted for 76.11% in a year. Some measures should be taken to protect karst water in the very near future, so that health risks to the local people can be decreased.  相似文献   

16.
Understanding factors influencing groundwater chemistry in regional groundwater basins is important to prevent groundwater pollution especially in arid areas where rainfall is low and water resources are limited. The present study assesses such factors in the regional, geologically diverse, groundwater basin of Wadi Umairy in Oman. The basin is composed of five different lithostratigraphic units with different hydraulic properties. Water samples (41) have been collected from the different units and analyzed for the major ions. Factor analysis and conventional hydrochemical methods were used to define the factors that have significant impact on the aquifer's hydrochemistry. It was found that evaporation and mineral weathering/dissolution are the main factors defining the groundwater chemistry along the flow path from recharge to discharge zones, whereas anthropogenic activities and alkalinity are found to be of lesser effect, and the latter prevails when the rocks are predominantly monomineralic. It was concluded that in regional groundwater basins, recharge/discharge relations together with the flow scale control the hydrochemistry irrespective of lithological variation in the basin.  相似文献   

17.
The hydrogeochemistry of saline-meteoric water interface zones in sedimentary basins is important in constraining the fluid migration history, chemical evolution of basinal brines, and physical stability of saline formation waters during episodes of freshwater recharge. This is especially germane for interior cratonic basins, such as the Michigan and Illinois basins. Although there are large differences in formation water salinity and hydrostratigraphy in these basins, both are relatively quiescent tectonically and have experienced repeated cycles of glaciation during the Pleistocene. Exploration for unconventional microbial gas deposits, which began in the upper Devonian-age Antrim Shale at the northern margin of the Michigan Basin, has recently extended into the age-equivalent New Albany Shale of the neighboring Illinois Basin, providing access to heretofore unavailable fluid samples. These reveal an extensive regional recharge system that has profoundly changed the salinity structure and induced significant biogeochemical modification of formation water elemental and isotope geochemistry.New-formation water and gas samples were obtained from Devonian-Mississippian strata in the Illinois Basin. These included exploration wells in the New Albany Shale, an organic-rich black shale of upper Devonian age, and formation waters from over- and underlying regional aquifer systems (Siluro-Devonian and Mississippian age). The hydrostratigraphic relations of major aquifers and aquitards along the eastern margin of the Illinois Basin critically influenced fluid migration into the New Albany Shale. The New Albany Shale formation water chemistry indicates significant invasion of meteoric water, with δD values as low as −46.05‰, into the shale. The carbon stable isotope system (δ13C values as high as 29.4‰), coupled with δ18O, δD, and alkalinity of formation waters (alkalinity ≤24.08 meq/kg), identifies the presence of microbial gas associated with meteoric recharge. Regional geochemical patterns identify the underlying Siluro-Devonian carbonate aquifer system as the major conduit for freshwater recharge into the fractured New Albany Shale reservoirs. Recharge from overlying Mississippian carbonates is only significant in the southernmost portion of the basin margin where carbonates directly overlie the New Albany Shale.Recharge of dilute waters (Cl− <1000 mM) into the Siluro-Devonian section has suppressed formation water salinity to depths as great as 1 km across the entire eastern Illinois Basin margin. Taken together with salinity and stable isotope patterns in age-equivalent Michigan Basin formation waters, they suggest a regional impact of recharge of δ18O- and δD-depleted fluids related to Pleistocene glaciation. Devonian black shales at both basin margins have been affected by recharge and produced significant volumes of microbial methane. This recharge is also manifested in different salinity gradients in the two basins because of their large differences in original formation water salinity. Given the relatively quiet tectonic history and subdued current topography in the midcontinent region, it is likely that repeated cycles of glacial meltwater invasion across this region have induced a strong disequilibrium pattern in fluid salinity and produced a unique class of unconventional shale-hosted gas deposits.  相似文献   

18.
Temporal variability of phosphorus fractions in Irish karst springs   总被引：1，自引：0，他引：1  
Transfer pathways of phosphorus (P) from soil to surface waters are the subject of much current research because of concerns about eutrophication. However, P transfer via groundwater discharge has received little attention. Temporal P changes at eight Carboniferous limestone karst springs from two catchments in western Ireland are examined. The eight springs were sampled fortnightly between June and October 1999 and thereafter monthly until February 2000. Each sample was analysed for total P (TP), total dissolved P (TDP) and dissolved reactive P (DRP). Total P exhibited some hydrological response at all springs (e.g. increase from 45 to 107 µg l–1) reflecting significant changes in particulate P (PP) (e.g. increase from 7 to 44 µg l–1) and dissolved organic P (DOP) (e.g. increase from 0 to 27 µg l–1), with DRP displaying greatest temporal stability. Greatest response to rainfall events occurred after the first major autumnal rains in September 1999, when there appeared to be dislodging of loosely bound PP and DOP, which was transported to groundwater. This response to the first autumnal rains probably reflects the hydrological switch where the catchments change from a soil moisture deficit to a soil moisture surplus situation. Daily autosampling demonstrated TP concentrations of up to 1,814 µg l–1 due to local pollution, highlighting the need to adopt storm event driven sampling rather than discrete sampling in karstic springs. Identification and management of springs in karst areas, with associated point recharge via swallow holes, presents an urgent and demanding challenge.  相似文献   

19.
The Limani-Yagoua mega sand-ridge, covering an area of 330,000 km2 is well know in the extreme north of Cameroun. Similar structures have also been described in the Chad Republic (Bongor-Koro-Toro), Niger (Tal) and Nigeria (Bama). Two possible origins can be considered: (i) circum-lacustrine around the Lake Chad Basin, interpreted as a Holocene or Pleistocene palæo-shoreline, or (ii) æolian accumulation as a mega sand dune in an area of basin subsidence. The sand-ridge in northern Cameroun is an extremely permeable aquifer with discharge rates of 3–6 m3 h−1. High nitrate levels (27–127 mg l−1) have been observed in several boreholes. Tritium at 4.1 ut indicates recent groundwater recharge, suggesting infiltration of rainfall damned by the sand-ridge.  相似文献   

20.
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.  相似文献   

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