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1.
Geochemical modeling of coal mine drainage, Summit County, Ohio 总被引:4,自引:1,他引:4
A. Foos 《Environmental Geology》1997,31(3-4):205-210
Geochemical modeling was used to investigate downstream changes in coal mine drainage at Silver Creek Metro-park, Summit
County, Ohio. A simple mixing model identified the components that are undergoing conservative transport (Cl–, PO4
3–, Ca2+, K+, Mg2+ and Na+) and those undergoing reactive transport (DO, HCO3
–, SO4
2–, Fe2+, Mn2+ and Si). Fe2+ is removed by precipitation of amorphous iron-hydroxide. Mn2+ are removed along with Fe2+ by adsorption onto surfaces of iron-hydroxides. DO increases downstream due to absorption from the atmosphere. The HCO3
– concentration increases downstream as a result of oxidation of organic material. The rate of Fe2+ removal from the mine drainage was estimated from the linear relationship between Fe+2 concentration and downstream distance to be 0.126 mg/s. Results of this study can be used to improve the design of aerobic
wetlands used to treat acid mine drainage.
Received: 4 June 1996 · Accepted: 17 September 1996 相似文献
2.
N. F. Gray 《Environmental Geology》1997,30(1-2):62-71
Work carried out at the abandoned copper (Cu) and sulphur (S) mine at Avoca (south east Ireland) has shown acid mine drainage
(AMD) to be a multi-factor pollutant. It affects aquatic ecosystems by a number of direct and indirect pathways. Major impact
areas are rivers, lakes, estuaries and coastal waters, although AMD affects different aquatic ecosystems in different ways.
Due to its complexity, the impact of AMD is difficult to quantify and predict, especially in riverine systems. Pollutional
effects of AMD are complex but can be categorized as (a) metal toxicity, (b) sedimentation processes, (c) acidity, and (d)
salinization. Remediation of such impacts requires a systems management approach which is outlined. A number of working procedures
which have been developed to characterise AMD sites, to produce surface water quality management plans, and to remediate mine
sites and AMD are all discussed.
Received: 16 January 1996 · Accepted: 5 March 1996 相似文献
3.
Sampling acid mine drainage (AMD) or natural acid rock drainage (ARD)-impacted sediments is complex, requiring appropriate
field sampling techniques to ensure representative samples that are both repeatable and reproducible. The important factors
affecting sampling of riverine sediments are examined. These include sample site location, field observations, representative
sampling, sample collection techniques, and sample preservation. A recommended sampling and processing protocol is presented
for AMD- and ARD-impacted riverine sediments, which includes sediment sampling, Fe hydroxide floc sampling, chemical analysis,
interstitial (pore) water collection, sediment elutriates, sediment fractionation, and physical analysis. The importance of
bioassay testing is discussed, as is quality assurance and assessment approaches to define sediment quality criteria.
Received: 18 September 1995 · Accepted: 23 October 1995 相似文献
4.
Hydrochemical characterization of acute acid mine drainage at Iron Duke mine, Mazowe, Zimbabwe 总被引:8,自引:0,他引:8
Acid mine drainage (AMD) with a minimum pH of 0.52 was recorded at Iron Duke mine near Mazowe, Zimbabwe during an investigation
of the environmental geochemistry of mine waters in the Greenstone Belts of Zimbabwe. Hydrochemical data for waters emanating
from the Iron Duke waste-rock pile indicate their super-saturation with respect to Fe and SO4
2–. Extremely high dissolved concentrations of Al, Zn, Cu, Co, Ni, V, Cr, Cd and As also prevail. Substantial losses of metals
from solution occur within 400 m of the AMD source through the precipitation of crystalline sulphates, principally melanterite.
Further downstream, hydrous oxide precipitation forms the dominant mechanism of metal attenuation in waters characteristically
under-saturated with respect to Fe sulphates. Speciation and saturation index data generated using the equilibrium model WATEQ4F,
suggest that such codes have broad utility for generic prediction of the mineralogical contraints on metal mobility in acute
AMD systems. Major discrepancies between modelled and empirical hydrochemistries are, however, evident for super-saturated
waters in which the kinetics of Fe precipitation are slow, and in which total ionic strengths markedly exceed their theoretical
maximum.
Received: 28 August 1998 · Accepted: 7 December 1998 相似文献
5.
Environmental geochemistry of the Gulf Creek copper mine area, north-eastern New South Wales, Australia 总被引:10,自引:3,他引:10
Past mining and smelting of sulphide ore (pyrite-chalcopyrite-sphalerite) at the abandoned Gulf Creek mine has resulted in
a stream highly contaminated by acid mine drainage (pH: 2.2–3.4), as well as degradation of local soil and vegetation. Physical
dispersion of secondary metal-bearing minerals from abandoned ore and waste dumps into Gulf Creek and adsorption and coprecipitation
of dissolved metals and metalloids in the stream bed cause elevated Ag, As, Cd, Cu, Fe, Pb and Zn values in stream sediments.
The bioavailability of individual heavy metals to freshwater organisms changes downstream, however, selective bioaccumulation
processes in algae reject readily bioavailable Zn and concentrate less bioavailable Cu. Polluted soils in the vicinity of
the mine and smelter sites are subject to continuing soil erosion and either support no vegetation, or a depauperate flora
with certain species showing bioaccumulation of metals and resistance to high metal contents. Rehabilitation of disturbed
areas should involve covering and sealing sulphidic mine waste or removal of ore and waste dumps, installation of a physical
and chemical plant or construction of a wetland environment (plus anoxic lime drains), and import of topsoil and planting
of local, metal-tolerant plant species.
Received: 17 March 1998 / Accepted: 6 October 1998 相似文献
6.
Acid mine drainage (AMD) occurs when sulfide minerals are exposed to an oxidizing environment. Most of the methods for preventing
AMD are either short-term or high cost solutions. Coating with iron phosphate is a new technology for the abatement of AMD.
It involves treating the sulfide with a coating solution composed of H2O2, KH2PO4, and sodium acetate as a buffer agent. The H2O2 oxidizes the sulfide surface and produces Fe3+ so that iron phosphate precipitates as a coating on the sulfide surface. Experiments performed under laboratory conditions
prove that an iron phosphate coating can be established on pyrrhotite surfaces with optimal concentrations of the coating
solution in the range of: 0.2M/0.01M H2O2, 0.2M KH2PO4, and 0.2M sodium acetate NaAc, depending on the experimental scale. Iron phosphate coating may be a long-term solution to
the problem of AMD. The method would be easy to implement; the reagent cost, however, is not low enough, although it is lower
than the conventional treatment with lime.
Received: 30 March 1995 · Accepted: 6 September 1995 相似文献
7.
Controls on the nature and distribution of an alga in coal mine-waste environments and its potential impact on water quality 总被引:2,自引:0,他引:2
A dominant non-bacterial microorganism that may strongly impact environmental conditions in acid mine drainage at several
Indiana coal mine sites is a single-celled protozoan, Euglena mutabilis. Field data suggest E. mutabilis has high tolerance for elevated total dissolved solids (TDS), to 18 g/l, and acid conditions to pH 1.7. Distribution is restricted
to unmixed effluent pH<4.6, with prolific growth between pH 3.0 and 3.5. Additional factors influencing E. mutabilis include preference for areas with lower mineral/colloidal precipitation rates and a stable substrate of iron-rich precipitates.
Initial studies indicate that in areas of prolific growth it contributes to oversaturation of dissolved oxygen by up to 200%.
The presence of small orange intracellular crystalline-like structures, similar in color to iron oxyhydroxides, suggests that E. mutabilis may be sequestering iron, and possibly other metals. Further work is needed to determine if E. mutabilis contributes to natural mitigation of poor water quality at these and other coal mine sites.
Received: 13 January 2000 · Accepted: 2 May 2000 相似文献
8.
Several mines in the Witbank coalfield in South Africa are affected by acid mine drainage. This has led to a deterioration
in the water quality in many surface streams. The Loubert Mine is one such mine. Hence, an initial investigation was carried
out to determine the source of acid mine drainage pollution and the associated hydrogeological conditions. The investigation
showed that most of the acid mine drainage is emanating from old opencast workings which have been backfilled. Most of the
water from the backfilled area drains into control reservoirs. Unfortunately their capacity is limited, which means that water
overspills and seeps from them. This water finds its way into a nearby stream, the water of which accordingly has an unacceptably
low pH value and high sulphate content. The proposals advanced to control the problem basically involve inhibiting the amount
of water infiltrating the backfilled opencast area on the one hand and reducing the amount of water entering the control reservoirs
on the other.
Received: 5 March 1997 · Accepted: 17 June 1997 相似文献
9.
Mineralogical constraints on the determination of neutralization potential and prediction of acid mine drainage 总被引:3,自引:1,他引:3
A. D. Paktunc 《Environmental Geology》1999,39(2):103-112
Acid-base accounting tests, commonly used as a screening tool in acid mine drainage (AMD) predictions, have limitations in
(1) measuring with confidence the amount of neutralizers present in samples and (2) affording an interpretation of what the
test results mean in terms of predicting the occurrence of acid mine drainage. Aside from the analytical difficulties inherent
to the conventional methods, a potential source of error in neutralization potential (NP) measurements is the contribution
from the dissolution of non-carbonate minerals. Non-carbonate alkalinity measured during static tests may or may not be available
to neutralize acidity produced in the field. In order to assess the value-added of extending the NP with the knowledge of
mineralogical composition and evaluate potential sources of errors in NP measurements, a suite of samples were examined and
characterized in terms of their mineralogical and chemical compositions. The results indicate that although the acid-base
accounting tests work well for simple compositions, the tests may result in overestimation or underestimation of NP values
for field samples. Mineralogical constraint diagrams relating NP determinations to Ca, Mg and CO2 concentrations were developed with the purpose to serve as supplementary guides to conventional static tests in identifying
possible NP contributions from non-carbonate minerals and checking the quality of the chemical testing results. Mineralogical
NP makes it possible to interpret the meaning of NP results and to assess the behaviour of samples over time by predicting
the onset of AMD and calculating NP values for individual size fractions.
Received: 1 June 1998 · Accepted: 6 October 1998 相似文献
10.
Iron oxyhydroxide precipitates associated with acid mine drainage (AMD) from the Stearns Coal Zone in southeastern Kentucky
were analyzed for their metal (Al, Cu, Pb, Mn, Ni, and Zn) content. The most concentrated metals within these sediments are
nickel (27–32×103μmol/kg), manganese (16–29×103μmol/kg), and aluminum (13–22×103μmol/kg) as determined by HCl-HNO3 digestion. Metal concentrations associated with the organic fraction as determined by H2O2 digestion were generally far lower, with the exception of aluminum. "Batch" experiments (at initial pH=2.0) were used to
analyze the stability of these metals associated with a contaminated soil. Aluminum was the most mobile of the metals, presumably
the result of the formation of aluminum-sulfate aqueous complexes. The solubilization rates for nickel and iron were very
similar, suggesting that nickel, unlike the other metals, coprecipitated with iron in these sulfatic oxyhydroxides.
Received: 9 October 1997 · Accepted: 15 December 1997 相似文献
11.
A comparative mineralogical and geochemical study of sulfide mine tailings at two sites in New Mexico, USA 总被引:5,自引:0,他引:5
A comparative study of sulfide mine tailings from two sites near Silver City in southwest New Mexico has shown the need for environmental monitoring in a geological context. The Cyprus-Piños Altos and Cleveland deposits consist of Cu and Zn skarn mineralization in the Piños Altos Mountains of New Mexico. Primary ore minerals in both deposits include chalcopyrite, sphalerite, and galena. The Cyprus-Piños Altos Mine ceased operation in 1995 and the Cleveland Mill closed in 1950. The deposits have similar mineralogical characteristics; however, the tailings are different in terms of age, degree of oxidation and method of disposal. The Cyprus-Piños Altos tailings (CPAT) are stored in a lined, bermed impoundment. They are dominantly water-saturated and exhibit no secondary-phase formation. The grains are not cemented and show no evidence of primary-mineral dissolution. The geochemical data show a predominantly primary signature. The tailings pond water is neutral to slightly alkaline (pH?from 7 to 8.3), partly as a result of processing methods. The Cleveland mill tailings (CMT) were deposited in a valley at the headwaters of an ephemeral stream. They are highly oxidized and differentially cemented. They have undergone numerous wet/dry cycles resulting in extensive oxidation. Secondary minerals predominate, and consist mainly of jarosite, goethite, hematite, and Fe-oxyhydroxides and -oxyhydroxysulfates. The pH of the stream draining the CMT is as high as 2.15. Maximum metal contents in the stream immediately downstream from the tailings are 5305?ppm Zn, 454?ppm Cu, 1.16?ppm Pb, 17.5?ppm Cd, 1.4?ppm As, and 0.01?ppm Hg. 相似文献
12.
Mineralogical study of base metal tailings with various sulfide contents, oxidized in laboratory columns and field lysimeters 总被引:7,自引:0,他引:7
S. C. Shaw L. A. Groat J. L. Jambor D. W. Blowes C. J. Hanton-Fong R. A. Stuparyk 《Environmental Geology》1998,33(2-3):209-217
Oxidation of a flotation-derived, low-sulfide tailings containing approximately 0.4 wt.% S was compared with simultaneously
oxidized tailings containing 1.0 wt.% S and 2.5 wt.% S to assess their acid generating characteristics. Each tailings type
was exposed to oxidation for three years in laboratory columns and in lysimeter pits in the field. In these tailings the sulfide
mineral of principal concern with respect to acid generation is pyrrhotite (Fe
1-x
S). In past studies the alteration of pyrrhotite has been characterized by initial replacement with marcasite (FeS2) and ferric iron sulfates, which are followed by development of ferric oxyhydroxides such as goethite and lepidocrocite.
Macroscopic characterization of the tailings shows varying and progressive degrees of oxidation correlative with the three
different sulfur contents. As expected, the tailings with the lowest sulfur content are the least oxidized, and those with
the highest sulfur content have reacted the most. The column tests, which represent accelerated reaction conditions relative
to those for the lysimeter pits, show much higher degrees of oxidation, and a markedly more distinct boundary between the
oxidized and unoxidized zones; as well, differences among the three tailings types are more pronounced.
Received: 31 October 1997 · Accepted: 27 May 1997 相似文献
13.
The potential formation of acid mine drainage in pyrite-bearing hard-coal tailings under water-saturated conditions: an experimental approach 总被引:5,自引:0,他引:5
Annually, an amount of approximately 13 million cubic meters of hard-coal tailings must be disposed of in the German Ruhr
Valley. Besides the waste of land in a densily populated region, the disposal of the pyrite-bearing material under atmospheric
conditions may lead to the formation of acid mine drainage (AMD). Therefore, alternative disposal opportunities are of increasing
importance, one of which being the use of tailings under water-saturated conditions, such as in backfilling of abandoned gravel
pits or in the construction of waterways. In this case, the oxidation of pyrite, and hence the formation of AMD, is controlled
by the amount of oxygen dissolved in the pore water of tailings deposited under water. In case the advective percolation of
water is suppressed by sufficient compaction of the tailings, oxygen transport can be reduced to diffusive processes, which
are limited by the diffusive flux of dissolved oxygen in equilibrium with the atmospheric pO2. Calculations of the duration of pyrite oxidation based on laboratory experiments have shown that the reduction of oxygen
is mainly controlled by the content of organic substance rather than the pyrite content, a fact that is supported by results
from oxidation experiments with nitrate. A "worst case" study has lead to the result that the complete oxidation of a 1.5-m
layer of hard-coal tailings deposited under water-saturated conditions would take as much as several hundred thousand years.
Received: 6 May 1996 · Accepted: 2 August 1996 相似文献
14.
Some problems associated with past mining at a mine in the Witbank coalfield, South Africa 总被引:2,自引:0,他引:2
Mining in the Witbank Coalfield commenced at the turn of the century. Initially there was little environmental degradation
associated with mining activities; however, in the late 1930s and early 1940s a pillar-robbing programme commenced. At one
particular mine this has had marked effects on the environment. Primary effects include subsidence, the appearance of tension
cracks at the surface and crownhole development. Secondary effects include spontaneous combustion of the coal worked, as air
has been provided with ready access to the mine, accelerated subsidence due to the strength of many pillars being reduced
by burning, and a marked deterioration in groundwater quality in the area. Spoil heaps also form blemishes on the landscape.
These contain significant amounts of coal and have undergone spontaneous combustion. The deterioration in the water quality
has led to the decimation of vegetation in some areas and the eradication of aquatic flora and fauna in a nearby stream.
Received: 5 March 1997 · Accepted: 1 July 1997 相似文献
15.
Anytime that tornadoes interface with people, the results are often grim. The varied characteristics of tornado windfields
and the diverse techniques of home construction complicate the expected outcomes of such interactions. Since it is now known
that tornadoes do not produce unfathomable winds, engineers have developed techniques for increasing a home’s tornado resistance;
thus, increasing the odds of survival of the inhabitants. Even considering these advances, tornadoes still wreak havoc and
cause much causality every year. The story of tornado survival is partly chance, partly knowledge, and partly science. This
essay utilizes analogies between a popular motion picture and the state of the art of tornado-resistant construction to illustrate
the good, the bad, and the ugly facts of tornado survival. First examined are the positive aspects of tornado probability.
The odds of experiencing a tornado are so low that massive expenditures are not necessarily cost effective. Next, various
techniques of tornado-resistant construction practices are included for new and existing structures. Introduction of equations
for predicting debris penetration are compared with various building techniques to describe the viability of tornado protection.
The negative aspect of tornado/structure interfaces describes the fact that despite contemporary construction and prevention
exercise, the unpredictability of the tornado windfield causes tremendous damage and loss of life. The final section examines
the interface between tornadoes and mobile homes. This proves very ugly in every aspect of the word. Statistics and equations
confirm the inherent dangers of such an interaction. Also, described is a novel approach to the design of a portable tornado
shelter. 相似文献
16.
Bo Peng Xiaoyan Tang Changxun Yu Shurong Xie Meilian Xiao Zhi Song Xianglin Tu 《Environmental Geology》2009,57(2):421-434
The acid mine drainage (AMD) discharged from the Hejiacun uranium mine in central Hunan (China) was sampled and analyzed using
ICP-MS techniques. The analyzing results show that the AMD is characterized by the major ions FeTotal, Mn, Al and Si, and is concentrated with heavy metals and metalloids including Cd, Co, Ni, Zn, U, Cu, Pb, Tl, V, Cr, Se,
As and Sb. During the AMD flowing downstream, the dissolved heavy metals were removed from the AMD waters through adsorption
onto and co-precipitation with metal-oxhydroxides coated on the streambed. Among these metals, Cd, Co, Ni, Zn, U, Cu, Pb and
Tl are negatively correlated to pH values, and positively correlated to major ions Fe, Al, Si, Mn, Mg, Ca and K. The metals/metalloids
V, Cr, Se, As and Sb are conservative in the AMD solution, and negatively-correlated to major ions Na, Ca and Mg. Due to the
above different behaviors of these chemical elements, the pH-negatively related metals (PM) and the conservative metals (CM)
are identified; the PM metals include Cd, Co, Ni, Zn, U, Cu, Pb and Tl, and the CM metals V, Cr, Se, As and Sb. Based on understanding
the geochemistry of PM and CM metals in the AMD waters, a new equation: EXT = (Acidity + PM)/pH + CM × pH, is proposed to
estimate and evaluate extent of heavy-metal pollution (EXT) of AMD. The evaluation results show that the AMD and surface waters
of the mine area have high EXT values, and they could be the potential source of heavy-metal contamination of the surrounding
environment. Therefore, it is suggested that both the AMD and surface waters should be treated before they are drained out
of the mine district, for which the traditional dilution and neutralization methods can be applied to remove the PM metals
from the AMD waters, and new techniques through reducing the pH value of the downstream AMD waters should be developed for
removal of the CM metals. 相似文献
17.
Seepage from a tailings dam is the major source of groundwater pollution in the Selebi-Phikwe area, where mining of sulphidic
nickel–copper–cobalt ore started in 1973 and will continue until 2014. The seepage water has a pH in the range of 1.7–2.8
and is strongly enriched in SO4
2− (5,680 g/L) and heavy metals (6,230 μg/L Ni, 1,860 μg/L Cu and 410 μg/L Co). The fracture aquifer affected by pollution from
the dam exhibits a remarkable capacity of heavy-metal sorption. Most of the Ni, Cu and Co is scavenged at less than 500 m
distance downgradient from the polluting source, whereas SO4
2− is not immobilized significantly. The heavy-metal sorption process is assumed to be due to surface complexation, which is
supported by a relatively high groundwater pH (in the range of 6.2–7.8 at >200 m distance from the tailings dam). The objective
of this study is to demonstrate that the sorption process can be incorporated into a realistic three-dimensional reactive-transport
groundwater model that is implicitly charge-balanced. The simulations are performed with the PHAST1.2 program, which is based
on the HST3D flow and transport code and the hydrochemical PHREEQC2.12 code. 相似文献
18.
The determination of neutralization potential (NP) of mining wastes is an essential part of waste characterization for acid
rock drainage (ARD) prediction. Interpretation of NP values requires consideration of the mineralogical composition of the
waste. Different minerals can neutralize acid drainage at different rates and in different pH ranges. The test conditions
of widely used laboratory procedures to determine NP do not distinguish between such differences and overestimation of NP
can often result. A simple procedure is proposed in which the effective NP is calculated based on mineralogical composition
and the relative reactivities of component minerals. Mineralogical composition is calculated from easily determined analytical
values using a CIPW normative procedure. Comparison of calculated NP values for 92 samples with experimentally determined
values from tests designed to prevent the overestimation of NP indicates that the method is successful in predicting an effective
NP value in most cases. The procedure is considered to be a cost-effective means of providing confident routine ARD prediction
when used in combination with other tests and analyses.
Received: 1 August 1996 / Accepted: 11 November 1996 相似文献
19.
Environmental pollution of Udaisagar lake and impact of phosphate mine, Udaipur, Rajasthan, India 总被引:6,自引:0,他引:6
B. K. Das 《Environmental Geology》1999,38(3):244-248
The study of water chemistry and sediment core samples from Udaisagar lake in Rajasthan has revealed high phosphate contents;
186 and 236 μg/l in surface and sub-surface waters and in core samples 0.157 wt % P2O5, low D.O. 4.61 and 3.50 mg/l on average in surface and depth waters and high E.C. 1316 and 1395 μs/cm and higher sedimentation
rate 8.90 mm/year in this lake compared to other lakes in the vicinity. The enormous and wide-spread growth of algal bloom
in lake water and Ahar river and occasional fish mortality are indications of eutrophic conditions prevailing in the lake.
Such a situation is developing due to the discharge of pollutants from phosphorite mines, chemical factories, distillary,
sewage and domestic waste from settlements, hotels throughout the length of River Ahar which during its journey receives and
finally discharges pollution in this lake. This renders the water unhygenic for human consumption and deleterious to aquatic
life.
Received: 27 January 1998 · Accepted: 28 September 1998 相似文献
20.
J.-Y. Yu 《Environmental Geology》1998,36(3-4):271-276
A few simple mass balance equations were developed to simultaneously estimate how much the pollutants from acid mine drainage
(AMD) in stream water are diluted and removed during their migration. The application of the equations requires knowledge
of the variations in the concentrations of the dissolved pollutants and the stoichiometry of the precipitation reaction of
the pollutants when none of the pollutant shows a conservative behavior along the stream path. The calculation should be restricted
to the pollutants showing much higher concentrations in the polluted main stream water than in the combining or diluting water
of the same target area.
The mass balance equations were applied to estimate the dilution factor and precipitation fractions of pollutants in Imgok
Creek such as Fe, SO4 and Al from the AMD of Yeongdong mine. The results show that the estimation, especially for SO4 and Al, significantly depends on the kinds of the precipitates. When FeOHSO4 and AlOHSO4 are assumed to precipitate, the maximum removal fractions of SO4 and Al by precipitation are respectively 34% and 46% of the original input, which is much higher than the values estimated
when SO4 is considered to be perfectly conservative. It indicates that the stoichiometry of precipitation reaction is very important
in the interpretation of the pollutant dilution and migration and assessment of environmental impacts of AMD. The applicability
of the mass balance equations may still need to be verified. However, examining the calculated dilution factor and precipitation
fractions with the equations can provide invaluable information on not only the behavior but also unexpected input of the
pollutants in the stream water polluted by AMD and other point sources.
Received: 12 November 1997 · Accepted: 30 March 1998 相似文献