共查询到20条相似文献,搜索用时 15 毫秒
1.
F. Ruiz M. L. González-Regalado J. Borrego J. A. Morales J. G. Pendón J. M. Muñoz 《Environmental Geology》1998,34(4):270-278
The Holocene filling of the Tinto-Odiel Estuary comprises seven lithofacies over a Mio-Pliocene substrate. The sequence includes
three system tracts: lowstand system (10 000 to 8700 years BP), transgressive system (8700 to 7000 years BP), and regressive
system (7000 to Recent). Twenty sediment samples from the 50-m borehole were analyzed for their major components and minor
element concentrations. Two multivariate analysis methods, principal component analysis and cluster analysis, were performed
in the analytical data set to help visualize the sample clusters and the element associations. Samples corresponding to unpolluted,
pre-mining sediments are clearly separated by cluster analysis, mainly as a result of the low content in sulphide-associated
heavy metals such as Cu, Zn, As, Ag, and Pb. So, these sediments may be utilized as a background for geochemical analysis
(bulk sample) in other adjacent estuaries, both in sandy and silty-clayey sediments. As a consequence of large-scale mining
and smelting operations occurred since prehistoric times on the river banks, a rapid rise in the metal pollution was found
in the upper 2.5 m of the natural filling, with values exceeding up to ten times the natural background levels. In addition,
since the mid-1960s, large amounts of waste and pollutant effluents have been discharged from industries located around the
estuary, increasing the heavy metal content in the last 0.3 m of the natural sedimentation.
Received: 18 August 1997 · Accepted: 19 January 1998 相似文献
2.
F. Lorenzo A. Alonso M. J. Pellicer J. L. Pagés M. Pérez-Arlucea 《Environmental Geology》2007,52(4):789-802
This research focuses on the development of metal pollution in sediment cores from three estuaries in Northwest Spain: Viveiro,
Ortigueira and Barqueiro. Pb, Cu, Co, Cr, Cd and Zn and total organic carbon were assessed using principal component analysis
(PCA) in order to obtain background values, measure pollution levels and identify pollution sources. Results were interpreted
by considering the local industrial history, grain size and C/N relationship. The pollution levels obtained bear a strong
resemblance to those documented for of a moderately industrialised area. PCA identifies factors that reflect mainly temporal
associations with metals. Sedimentation rates between 0.9 and 1.1 cm/year were determined. In Viveiro core levels of Cr pollution
are associated with tanneries. In Ortigueira, high core levels of Cu and Co are linked to mining, and Cr levels to adjacent
ultramafic rocks. Erosion of Holocene sediment causes high values of Co and Cr in the Barqueiro core. Cu increase in the three
estuaries is related to fungicide use since 1910. Sea level rise appears to be affecting the marine characteristics of the
sediments in Barqueiro. In Viveiro, the nature of the sediment reflects engineering work and land reclamation. 相似文献
3.
A. M. Caredda A. Cristini C. Ferrara M. F. Lobina M. Baroli 《Environmental Geology》1999,38(2):91-100
We have studied sediments of the Piscinas beach (SW Sardinia, Italy), which is supplied by two streams that wash mine dumps
of abandoned lead and zinc mines at Montevecchio and Ingurtosu, situated inland from the supply basin of the beach itself.
A study of the texture, mineralogy and geochemistry of the sediments was conducted for the purpose of assessing the possible
influence of the mine waste on the composition of the sediments, looking for any anomalous enrichments in heavy metals. Furthermore,
to evaluate and quantify metal release into the sea, samples of Posidonia oceanica, a bioaccumulator marine plant, were also examined. The results indicate that the distribution of heavy metals in the foreshore
sediments is particularly affected by the contribution of the streams, while in the shoreface the distribution is affected
by the currents that disperse the sediments both out to sea and southwards. The metal contents of the Posidonia oceanica are correlated with the different stages of activity of the mines.
Received: 28 January 1998 · Accepted: 22 April 1998 相似文献
4.
D. Ciszewski 《Environmental Geology》1997,29(1-2):50-57
The influence of sources of effluents on pollution of bottom sediments of the small Chechło River (23 km long, mean discharge
1.5 m3 s–1) in southern Poland was examined through analysis of heavy metals distribution in transverse and longitudinal cross sections.
Underground waters from a Pb–Zn mine cause very high concentrations of Zn, Cd, and Pb in both fractions investigated (<1 mm
and <0.063 mm) of sediments in the active channel zone, whereas sedimentation of huge amounts of suspended matter discharged
from oil refinery cause concentrations of heavy metals in fine fractions rather uniform in cross sections. In the lowest reach,
with relatively reduced contamination, the highest concentration both in fine and coarse fractions occurs close to the river
banks and in the deepest points of the channel. The lowest concentrations have been found at the points of strongest reworking
and accumulation of sandy material in the riverbed.
Received: 25 April 1995 · Accepted: 11 September 1995 相似文献
5.
The most commonly recognized sources of sand and gravel aggregate are the deposits of coastal, fluvial and glacial sedimentary
processes. It is not commonly recognized that weathered bedrock is also an important source of sand and gravel aggregate.
In the case of weathered sedimentary bedrock the product may be indistinguishable from modern sedimentary materials and deposits
may be misidentified. Batson's quarry is a major sand and gravel aggregate resource for the rapidly developing region of north-eastern
New South Wales. The deposit has previously been assumed to be a young sedimentary deposit, but detailed field examination
and comparison with surrounding rock types indicates that it has formed from weathered Mesozoic sandstone bedrock. The extraction
of weathered bedrock aggregate deposits has distinctive environmental implications because, unlike sedimentary aggregates,
they are not restricted by the geometry of sedimentary environments and do not necessarily interfere with surface drainage
systems. This study shows that the recognition of the geological origin of a resource is essential in order to determine its
potential geographical extent, and thereby maximize its utilization and minimize land use conflict.
Received: 3 January 1996 / Accepted: 1 November 1996 相似文献
6.
Mine waste dumps and heavy metal pollution in abandoned mining district of Boccheggiano (Southern Tuscany, Italy) 总被引:11,自引:1,他引:11
M. Benvenuti I. Mascaro F. Corsini P. Lattanzi P. Parrini G. Tanelli 《Environmental Geology》1997,30(3-4):238-243
Mining activity in the Boccheggiano-Fontalcinaldo area (Southern Tuscany) dates back at least to the 16th century AD and
lasted up to very recent times. Copper-rich hydrothermal veins, massive pyrite deposits, and their gossans were exploited.
Two mine waste dumps (Fontalcinaldo, Fontebona), one flotation tailings impoundment (Gabellino), and one roasting/smelting
waste dump (Merse-Ribudelli) in the study area were selected to ascertain the environmental effects of such protracted mining
activity. Primary waste mineralogy is mainly characterized by pyrite, gypsum, quartz, carbonates, chlorites, and micas. Secondary
oxidation mineralogy includes Fe and Cu sulfates and hydroxy sulfates, Cu carbonates, Fe and Al oxyhydroxides, and other phases
[neogenic cassiterite at Fontalcinaldo; probable calkinsite, (Ce,La)2(CO3)3· 4H2O, at Fontebona]. Mine waste samples show extremely variable contents of toxic elements (Cu, Pb, Zn, Bi, Cd, As), with average
values in the order of hundreds to thousands of parts per million (except for Bi and Cd). In some samples, the abundance of
proper minerals of these metals cannot account for the entire metal load. Conceivably, either solid solution substitutions
or adsorption processes contribute to the intake of released metals into newly formed minerals. Release and transport of pollutants
was affected to variable degrees by acid-neutralization processes. The highest metal and acid concentrations occur close to
the investigated wastes and rapidly decrease moving downstream some hundreds of meters or less, with the partial exception
for Mn and Fe. Other than dilution effects, this phenomenon may be ascribed to metal adsorption and precipitation of solid
phases.
Received: 16 April 1995 · Accepted: 14 December 1995 相似文献
7.
The variation of the oxygen content in olivines, (Fe
x
Mg1−
x
)2SiO4, with 0.2 ≤ x ≤ 1.0, was investigated by thermogravimetric measurements. Mass changes occurring upon oxygen activity changes were measured
as a function of oxygen activity and cationic composition at 1130 and 1200 °C. During the measurements the samples were in
direct contact with gases containing CO, CO2 and N2 and, at a few spots at the bottom of the sample stack, also with SiO2. By fitting experimental data of mass changes to equations derived using point defect thermodynamics, it was shown for olivines
with 0.2 ≤ x ≤ 1.0 at 1130 °C and 0.2 ≤ x ≤ 0.7 at 1200 °C within the oxygen activity ranges investigated that the observed variations in the oxygen contents are compatible
with cation vacancies and Fe3+ ions on M sites and Fe3+ ions on silicon sites as majority defects if it is assumed that only three types of point defects occur as majority defects.
Different cases were considered, closed systems, taking into account that ξ=[Si]/([Si]+[Fe]+[Mg]) is not necessarily equal
to 1/3, and olivines in equilibrium with SiO2 or pyroxenes. The oxygen content variations observed in this study are significantly smaller than those reported previously
in the literature. It is proposed that these differences are related to the dissolution of Fe into noble metal containers
used as sample holders in earlier studies and/or to the presence of secondary phases.
Received: 1 November 1995 / Accepted: 15 September 2002
Acknowledgements This work was supported by the Cornell Center for Materials Research (CCMR), a Materials Research Science and Engineering
Center of the National Science Foundation (DMR-0079992). The authors thank Mr. Daniel M. DiPasquo and Mr. Jason A. Schick
for helping in experimental work. 相似文献
8.
Heavy metals in freshly deposited sediments of the Gomati River (a tributary of the Ganga River): effects of human activities 总被引:10,自引:0,他引:10
The concentrations of various metals (Cr, Cu, Co, Fe, Mn, Ni, Pb, Zn, and Cd) were determined in recently deposited surface
sediments of the Gomati River in the Lucknow urban area. Markedly elevated concentrations (milligrams per kilogram) of some
of the metals, Cd (0.26–3.62), Cu (33–147), Ni (45–86), Pb (25–77), and Zn (90–389) were observed. Profiles of these metals
across the Lucknow urban stretch show a progressive downstream increase due to additions from 4 major drainage networks discharging
the urban effluents into the river. The degree of metal contamination is compared with the local background and global standards.
The geoaccumulation index order for the river sediments is Cd>Zn>Cu>Cr>Pb. Significant correlations were observed between
Cr and Zn, Cr and Cu, Cu and Zn and total sediment carbon with Cr and Zn. This study reveals that the urbanization process
is associated with higher concentrations of heavy metals such as Cd, Cu, Cr, Pb, and Zn in the Gomati River sediments. To
keep the river clean for the future, it is strongly recommended that urban effluents should not be overlooked before their
discharge into the river.
Received: 16 February 1996 · Accepted: 29 February 1996 相似文献
9.
Dreissena polymorpha is an exotic freshwater bivalve species which was introduced into the Great Lakes system in the fall of 1985 through the release
of ballast water from European freighters. Utilizing individual growth rings of the shells, the stable isotope distribution
(δ18O and δ13C) was determined for the life history of selected samples which were collected from the western basin of Lake Erie. These
bivalves deposit their shell in near equilibrium with the ambient water and thus reflect any annual variation of the system
in the isotopic records held within their shells. Observed values for δ18O range from -6.64 to –9.46‰ with an average value of –7.69‰ PDB, while carbon values ranged from –0.80 to –4.67‰ with an
average value of –1.76‰ PDB. Dreissena polymorpha shells incorporate metals into their shells during growth. Individual shell growth increments were analyzed for Pb, Fe, Mg,
Mn, Cd, Cu, and V concentrations. The shells show increased uptake of certain metals during periods of isotopic enrichment
which correspond with warmer water temperatures. Since metals are incorporated into the shells, the organism may be useful
as a biomonitor of metal pollution within aquatic environments.
Received: 31 October 1996 · Accepted: 21 May 1997 相似文献
10.
Dariusz Ciszewski 《Environmental Geology》1998,36(1-2):45-54
An evaluation of the influence of channel processes (erosion, accumulation, processing of channel sediments) on the dispersal
of heavy metals in bottom sediments was carried out in the channels of the Sztoła and Biała Przemsza rivers in Upper Silesia,
Poland. These rivers receive waters from a Zn and Pb mine. Mine waters transport a large amount of fine-grained sediments
contaminated with heavy metals. The polluted material is accumulated in these stream courses and mixed with nearly homogeneous
sandy sediment derived from erosion of the river banks and bed. Because these alluvia are easily set in motion, the distribution
of heavy metal concentration in the channel in fraction <1 mm reflects differences in physical processes of sedimentation
in its cross-section. The minimal values in active channel and maximal in the near-bank zone are typical for those channel
sections where heavy metals, present in a solid state, are transported as a suspended load (normally the largest part of a
polluted river course). In short sections heavy metals associated with the grains of a large mass which has accumulated in
the active channel are transported as a bed load and the typical distribution pattern is reversed (in fractions both <1 mm
and <0.063 mm). Such regularities can be disturbed in localities where strong, turbulent flow or frequent eddying occur and
Mn oxides and hydrooxides and associated elements precipitate. The smallest variation in heavy metal concentration in the
homogenous, fine-grained bank sediments which are trapped by plants below water level is a feature which recommends these
localities as being the most suitable for monitoring of river pollution.
Received: 11 November 1997 · Accepted: 12 March 1998 相似文献
11.
Geochemistry of Cu, Co, Ni, Zn, Cd and Cr in the surficial sediments of a tropical estuary, southwest coast of India: a granulometric approach 总被引:3,自引:0,他引:3
Geochemical characteristics of six trace metals – Cu, Co, Ni, Zn, Cd and Cr – in the bulk sediment and sand, silt and clay
fractions of a tropical estuary on the southwest coast of India have been studied and discussed. In bulk sediment, the trace
metal concentration is controlled mainly by the textural composition of the sample. Mud, sandy mud and sandy silt register
higher concentrations of trace metals than that in sand-dominant sediments. The granulometric partitioning studies also re-affirmed
the role of particle size in enriching the trace metals. The silt and clay fractions exhibit 7–8 times the enrichment of Cu
and Cd compared to that in sand. The enrichment factors of Zn, Cr, Ni and Co in the silt and clay fractions, compared to that
in sand, are 5–6, 4–5, 2–5 and 2–3 times, respectively. The trace metals in the sand fraction, particularly Ni and Cr, exhibit
strong positive correlation with the heavy mineral content of the samples. It clearly indicates a heavy mineral pathway to
the trace metals in the sand fraction. Cu and Co in silt and clay fractions exhibit a marked decrease towards the high saline
zones of the estuary. This is attributed to the desorption of Cu and Co from particulate phases during estuarine mixing. Contrary
to Cu and Co, the content of Zn in the clay fraction shows a marginal increase towards the estuarine mouth. This could be
explained by the influx of Zn-rich contaminant discharges from Zn-smelting industries located slightly north of the estuarine
mouth. The released Zn will effectively be held in the lattices of the clay mineral montmorillonite, which also exhibits a
marked increase towards the estuarine mouth. The anomalously high values of Cd in some places of the Central Vembanad estuary
is attributed to the local pollution.
Received: 10 July 1995 · Accepted: 3 June 1996 相似文献
12.
Munendra Singh 《Environmental Geology》2001,40(6):664-671
The Yamuna River sediments, collected from Delhi and Agra urban centres, were analysed for concentration and distribution
of nine heavy metals by means of atomic adsorption spectrometry. Total metal contents varied in the following ranges (in mg/kg):
Cr (157–817), Mn (515–1015), Fe (28,700–45,300), Co(11.7–28.4), Ni (40–538), Cu (40–1204), Zn (107–1974), Pb (22–856) and
Cd (0.50–114.8). The degree of metal enrichment was compared with the average shale concentration and shows exceptionally
high values for Cr, Ni, Cu, Zn, Pb and Cd in both urban centres. In the total heavy metal concentration, anthropogenic input
contains 70% Cr, 74% Cu, 59% Zn, 46% Pb, 90% Cd in Delhi and 61% Cr, 23% Ni, 71% Cu, 72% Zn, 63% Pb, 94% Cd in Agra. A significant
correlation was observed between increasing Cr, Ni, Zn, and Cu concentrations with increasing total sediment carbon and total
sediment sulfur content. Based on the Müller's geoaccumulation index, the quality of the river sediments can be regarded as
being moderately polluted to very highly polluted with Cr, Ni, Cu, Zn, Pb and Cd in the Delhi and Agra urban centres. The
present sediment analysis, therefore, plays an important role in environmental measures for the Yamuna River and the planning
of these city centres.
Received: 21 June 1999 · Accepted: 1 October 1999 相似文献
13.
Background concentrations of heavy metals in aquatic bryophytes used for biomonitoring in basaltic areas (a case study from central France) 总被引:1,自引:0,他引:1
Studies were made of the aquatic bryophytes Fontinalis antipyretica Hedw., Platyhypnidium rusciforme (Neck.)Fleisch and Chiloscyphus sp. (Hoffm.)Dum. from streams embedded in basaltic rocks (Le Puy, central France). Water from these streams possessed elevated
levels of Cu, Zn, Sr, V, Ba, Ni and Co, reflecting the geochemistry of the basalts, a basic type of igneous rocks containing
elevated levels of these elements. The concentration of elements in bryophytes is correlated to the chemical composition of
water of their sampling sites. Contents of trace elements in plants were higher than background values. The elevated levels
of these elements possibly caused disturbances in the ionic equilibrium within the bryophytes. The molar ratio between contents
of Ca and Mg in water (from 0.44 to 1) was different from that typical for natural water.
Received: 16 September 1998 · Accepted: 17 December 1998 相似文献
14.
The deviation from stoichiometry, δ, in spinel solid solutions of the type (Ti
x
Fe
1−x
)3−δ O4 with x=0.1, 0.2 and 0.25 was studied thermogravimetrically as a function of oxygen activity, a
O2, at 1100, 1200 and 1300 ∘C. The experimental results, S-shaped curves for δ vs. log aO2, are presented and discussed with regard to the type of point defects prevailing under different conditions in the deviation
from stoichiometry. It is concluded that cation vacancies are the predominant point defects at high oxygen activities, while
cation interstitials prevail at low oxygen activities. The temperature and composition dependencies of point defect concentrations
are also discussed.
Received: 1 October 1996 / Accepted: 15 September 2002
Acknowledgements The authors thank the US Department of Energy for support of this work under Grant no. DE-FGO2–88ER45357. This work made
use of the Cornell Center of Materials Shared Experimental Facilities, supported through the National Science Foundation Materials
Research Science and Engineering Centers program (DMR-0079992). 相似文献
15.
Bond critical point properties of electron density distributions calculated for representative Si5O16 moieties of the structure of coesite are compared with those observed and calculated for the bulk crystal. The values calculated
for the moieties agree with those observed to within ∼5%, on average, whereas those calculated for the crystal agree to within
∼10%. As the SiOSi angles increase and the SiO bonds shorten, there is a progressive build-up in the calculated electron density
along the bonds. This is accompanied by an increase in both the curvatures of the electron density, both perpendicular and
parallel to each bond, and the Laplacian of the electron density distribution at the bond critical points. The cross sections
of the bonds at the critical points become more circular as the angle approaches 180o. Also, the bonded radius of the oxide
anion decreases about twice as much as that of the Si cation as the SiO bond length decreases and the fraction of s-character of the bond is indicated to increase. A knowledge of electron density distributions is central to our understanding
of the forces that govern the structure, properties, solid state reactions, surface reactions and phase transformations of
minerals. The software (CRYSTAL95 and TOPOND) used in this study to calculate the bond critical properties of the electron
density and Laplacian distributions is bound to promote a deeper understanding of crystal chemistry and properties.
Received: 23 February 1998 / Revised, accepted: 16 July 1998 相似文献
16.
Retention ponds have been dug along some of the motorways in France to minimize environmental pollution by keeping pollutants
from spreading over the surrounding area. In the current work, eight core samples were collected from the bottom of a retention
pond located along the A-71 motorway in Sologne to study the pollution of sediment by heavy metals and their diagenetic behaviour.
The vertical concentration profiles of metals (Pb, Zn, Cd, Fe and Mn) in sediment as well as in interstitial water were determined.
Especially in the case of the sediment, a sequential extraction method was employed to investigate how the movement of each
metal is associated with the other metals and with other solid phases such as organic matter. In addition, to investigate
the relative mobility of the metals, the distribution coefficients (KD) were also determined. The concentrations of the metals were always found to be highest in the topmost layer of sediment.
This so-called surface enrichment is caused by a substantial increase of the non-detrital fraction of these metals at the
sediment surface. For instance, the accumulation of Pb and Zn is associated with the increase in the "fraction II" in the
sequential extraction. The accumulation of Cd at the surface (0–2 cm) is partly due to the liberation of Cd from the particles
during early diagenesis. However, the major factor contributing to the accumulation of Cd at the sediment surface is attributed
to the dissolution of Cd from polluted roadside soil during the periods of rainstorms and its subsequent redeposition on the
sediment surface after being carried to the retention pond. KD values for Zn and Cd were found to decrease with depth, while KD values for Pb increased. Based on the KD values, the relative mobilities of the studied metals were determined to be as follows: Mn>Zn>Cd>Pb, for the upper layer,
and Mn>Cd>Zn>Pb, for the layers below.
Received: 28 October 1996 / Accepted: 21 November 1996 相似文献
17.
Standardization of metal concentrations in sediments using regression residuals: an example from a large lake in Florida, USA 总被引:6,自引:0,他引:6
A new method of standardizing metal concentrations in sediments was tested on samples from Lake Miccosukee, a large karstic
lake in north Florida. Metal concentrations were analyzed in 222 sediment samples from 26 cores representing 9 sampling sites
in the lake. Measured sedimentation rates in the lake are low. Percent organic matter strongly increases upward in all the
cores. The C/N ratio remains constant throughout all the samples, with a mean value of about 13, regardless of depth or location.
All of the geochemical variables are at least approximately log-normally distributed; thus, log-log or semi-log scattergrams
were used and the data were log-transformed before statistical calculations were performed. Some elements (Mn, Zn, Hg, Cu,
and Ca) are primarily associated with the organic fraction; others (La, Cr, Sr, and Ba) are clearly related to the terrigenous
fraction; others show affinities for both fractions. Consequently, no bivariate scattergrams or plots of ratio versus depth
– commonly used for standardization by plotting or ratioing a reference element (such as Al) to an element of interest – were
found to be adequate for standardization of this dataset. The best method for standardization was found to be one based on
multivariate (trivariate) linear regression, using log Al and log C as the independent variables (reference elements representing
terrigenous and organic fractions, respectively), and the log of the element of interest as the dependent variable. Residuals
(deviations) from the best-fit linear surface were then plotted versus depth in the cores to accomplish the standardization.
The results indicate that, with the possible exception of Mn at two sites, there is little evidence of anthropogenic input
of trace elements to the lake, and most trace-element concentrations in the lake can be considered as valuable baseline information.
A significant finding is that different and erroneous conclusions might have been reached if other standardization methods,
not based on trivariate regression, had been employed.
Received: 28 August 1997 · Accepted: 24 November 1997 相似文献
18.
Chemical composition of landfill leachate in a karst area with a Mediterranean climate (Marbella, southern Spain) 总被引:2,自引:0,他引:2
I. Vadillo F. Carrasco B. Andreo A. García de Torres C. Bosch 《Environmental Geology》1999,37(4):326-332
Between March 1994 and April 1997, the physical and chemical parameters and chemical composition of the urban solid waste
leachate of the Marbella landfill (southern Spain) were determined. The data obtained show an ammonium and sodium chloride
and bicarbonate type, a pH>7 and high mineralization, effectively described by the following parameters: Na+, K+, NH4
+, Cl– and alkalinity. The chemical composition depends on the rainfall: in dry years, the mineralization and component concentrations
have values as much as double those found in normal rainfall years. After storm events, a major and rapid dilution (within
several hours) is seen in the leachate.
Received: 28 January 1998 · Accepted: 2 June 1998 相似文献
19.
Water vulnerability assessment in karst environments: a new method of defining protection areas using a multi-attribute approach and GIS tools (EPIK method) 总被引:42,自引:12,他引:30
Groundwater resources from karst aquifers play a major role in the water supply in karst areas in the world, such as in Switzerland.
Defining groundwater protection zones in karst environment is frequently not founded on a solid hydrogeological basis. Protection
zones are often inadequate and as a result they may be ineffective. In order to improve this situation, the Federal Office
for Environment, Forests and Landscape with the Swiss National Hydrological and Geological Survey contracted the Centre of
Hydrogeology of the Neuchatel University to develop a new groundwater protection-zones strategy in karst environment. This
approach is based on the vulnerability mapping of the catchment areas of water supplies provided by springs or boreholes.
Vulnerability is here defined as the intrinsic geological and hydrogeological characteristics which determine the sensitivity
of groundwater to contamination by human activities. The EPIK method is a multi-attribute method for vulnerability mapping
which takes into consideration the specific hydrogeological behaviour of karst aquifers. EPIK is based on a conceptual model
of karst hydrological systems, which suggests considering four karst aquifer attributes: (1) Epikarst, (2) Protective cover,
(3) Infiltration conditions and (4) Karst network development. Each of these four attributes is subdivided into classes which
are mapped over the whole water catchment. The attributes and their classes are then weighted. Attribute maps are overlain
in order to obtain a final vulnerability map. From the vulnerability map, the groundwater protection zones are defined precisely.
This method was applied at several sites in Switzerland where agriculture contamination problems have frequently occurred.
These applications resulted in recommend new boundaries for the karst water supplies protection-zones.
Received: 27 October 1997 · Accepted: 4 July 1998 相似文献
20.
In the northern Schwarzwald (Moldanubian Zone of the Variscan belt), paragneisses drilled from approximately 2500 m depth
at the Bühl-1 drilling site have experienced amphibolite-facies metamorphism and were later partly transformed to mylonites
under greenschist-facies conditions. Completely graphitised acritarchs and chitinozoans were recovered from these paragneisses
and mylonitic gneisses. Whereas both groups of palynomorphs give evidence of a marine depositional environment, only the chitinozoans
are stratigraphically useful in this case and indicate a Paleozoic age. Previous findings of acritarchs in a different high-grade
metamorphic gneiss unit within the Schwarzwald indicate an Upper Proterozoic marine sedimentation age. The spectrum of palynomorphs
found thus far in the Schwarzwald in combination with petrological data suggests that within the Moldanubian domain of the
Armorican microplate, rocks with different sedimentary records later experienced diverging prograde metamorphic histories.
In general, the results reveal that palynological studies in combination with petrological data are a promising tool for reconstructing
pre-orogenic settings in collisional belts.
Received: 17 July 1998 / Accepted: 19 January 1999 相似文献