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61.
Trace elements contamination of agricultural soils affected by sulphide exploitation (Iberian Pyrite Belt,Sw Spain) 总被引:1,自引:0,他引:1
Agricultural soils of the Riotinto mining area (Iberian Pyrite Belt) have been studied to assess the degree of pollution by
trace elements as a consequence of the extraction and treatment of sulphides. Fifteen soil samples were collected and analysed
by ICP-OES and INAA for 51 elements. Chemical analyses showed an As–Cu–Pb–Zn association related with the mineralisation of
the Iberian Pyrite Belt. Concentrations were 19–994 mg kg−1 for As, 41–4,890 mg kg−1 for Pb, 95–897 mg kg−1 for Zn and of 27–1,160 mg kg−1 for Cu. Most of the samples displayed concentrations of these elements higher than the 90th percentile of the corresponding
geological dominium, which suggests an anthropogenic input besides the bedrock influence. Samples collected from sediments
were more contaminated than leptosols because they were polluted by leachates or by mining spills coming from the waste rock
piles. The weathering of the bedrock is responsible for high concentrations in Co, Cr and Ni, but an anthropogenic input,
such as wind-blown dust, seems to be indicative of the high content of As, Cu, Pb and Zn in leptosols. The metal partitioning
patterns show that most trace elements are associated with Fe amorphous oxy-hydroxides, or take part of the residual fraction.
According to the results obtained, the following mobility sequence is proposed for major and minor elements: Mn, Pb, Cd, > Zn,
Cu > Ni > As > Fe > Cr. The high mobility of Pb, Cu and Zn involve an environmental risk in this area, even in soils where
the concentrations are not so high. 相似文献
62.
Daniel Bernard Jamal El Khattabi Emilie Lefevre Hani Serhal Sabine Bastin-Lacherez Isam Shahrour 《Environmental Geology》2008,53(5):1129-1138
In the north of France, high registers of nickel are sometimes recorded within the chalk aquifer. In a confined context, the
presence of pyrite in the covering clays or in the marcasite nodules encrusted in the clay may constitute a natural source
of trace metals. With an objective of sanitary control, the limits of chemical contents regulating the quality of water destined
for human consumption have been lowered by the European Framework Directive in the field of water policy (2000/60/EC). As
a result, nickel limits have been reduced from 50 to 20 μg/l. The analyses, carried out on three water catchment fields in
our area of study, were centred on variable parameters (Eh, O2(d), pH, Conductivity, T°), major elements (SO4, NO3) and metals (Fe, Ni, Mn, Co). The acquired data enabled us to identify from one hand, the conditions which are presented
within the site, special thanks to the evolution of nitrate and iron contents and on the other hand, the natural origin (geological)
of nickel for two of the three sites studied based essentially on the evaluation of the Nickel/Cobalt ratio. Thus, on the
first site, the evolution of nickel content and nitrate content showed the influence of the phenomenon of denitrification
on the re-mobilisation of the nickel. Whereas on the second site, a high variation of total iron content and oxygen dissolved
in solution highlighted a particular phenomenon of oxidation of the pyrite through molecular oxygen. Finally, the correlation
with the sulphates clearly showed behaviour of the nickel, once released, that was entirely dependent on the phenomenon of
adsorption on the iron and manganese hydroxides. 相似文献
63.
Mahmoud M. El Banna 《Environmental Geology》2008,54(6):1291-1299
Types, distribution, and origin of recent sand dunes between Rosetta and Idku, in the western sector of the Nile Delta, Egypt
were investigated. Sand samples from the dunes, beach, and seafloor were studied for grain size distribution and mineralogical
composition. It has been found that most of the dunes in the study area have been subjected to deterioration and removal due
to the construction of buildings and the International Coastal Highway. The remnant constitutes a damaged belt of foredunes
that extends from El Bouseily village to the west of Idku town. The dune’s origin is interpreted to be the result of coastal
drifting and the subsequent transport of sediments of the former Canopic Nile branch eastward by the predominant longshore
current and by aeolian processes. The blown sand grains accumulated to form a belt of coastal sand dunes of original longitudinal
and crescentic forms. Urbanization of the coast has severely altered the landscape. The study area is considered vulnerable
to the impacts of climate change and the expected rise in sea level. The outcome of potential sea level rise is serious; erosion
problems are expected to be exacerbated and vast areas from land and property would be lost. Thus, protection and preservation
the remaining dunes in the study area are vital requirements for shore protection. 相似文献
64.
N. Nur Ozyurt 《Environmental Geology》2008,54(4):731-736
Salinity and temperature variations in groundwater discharge from the Altug submarine karst cave have been observed at 28 m
below sea level for every 10 min between November 2004 and August 2005 to determine the drivers that govern the salinization.
Comparisons between temporal trends of salinity and temperature with those of precipitation, air pressure, sea level and wind
velocity revealed an apparent dominance of precipitation regime on the salinity and temperature variations. Spectral analyses
applied to observations showed that the air pressure and sea level oscillations are affected by sun and moon tides which do
not have an appreciable impact on the salinity and temperature variations. Annual rate of salinization in Altug cave seems
inversely related to the inland groundwater head so that the maximum and minimum fresh water contributions occur at mid-spring
and late-summer, respectively. 相似文献
65.
Landslide susceptibility mapping for a landslide-prone area (Findikli,NE of Turkey) by likelihood-frequency ratio and weighted linear combination models 总被引:17,自引:0,他引:17
Landslides are very common natural problems in the Black Sea Region of Turkey due to the steep topography, improper use of
land cover and adverse climatic conditions for landslides. In the western part of region, many studies have been carried out
especially in the last decade for landslide susceptibility mapping using different evaluation methods such as deterministic
approach, landslide distribution, qualitative, statistical and distribution-free analyses. The purpose of this study is to
produce landslide susceptibility maps of a landslide-prone area (Findikli district, Rize) located at the eastern part of the
Black Sea Region of Turkey by likelihood frequency ratio (LRM) model and weighted linear combination (WLC) model and to compare
the results obtained. For this purpose, landslide inventory map of the area were prepared for the years of 1983 and 1995 by
detailed field surveys and aerial-photography studies. Slope angle, slope aspect, lithology, distance from drainage lines,
distance from roads and the land-cover of the study area are considered as the landslide-conditioning parameters. The differences
between the susceptibility maps derived by the LRM and the WLC models are relatively minor when broad-based classifications
are taken into account. However, the WLC map showed more details but the other map produced by LRM model produced weak results.
The reason for this result is considered to be the fact that the majority of pixels in the LRM map have high values than the
WLC-derived susceptibility map. In order to validate the two susceptibility maps, both of them were compared with the landslide
inventory map. Although the landslides do not exist in the very high susceptibility class of the both maps, 79% of the landslides
fall into the high and very high susceptibility zones of the WLC map while this is 49% for the LRM map. This shows that the
WLC model exhibited higher performance than the LRM model. 相似文献
66.
In this study, dynamic behavior and earthquake resistance of Alibey earth dam was investigated. The dam was modeled with four
node plane-strain finite elements (FE) and displacement-pore pressure coupled FE analyses were performed. Nonlinear material
models such as pressure dependent and independent multi yield materials were implemented during the analyses. Transient dynamic
FE analyses were performed with Newmark method. The Newton-Raphson solution scheme was adopted to solve the equations. Liquefaction
and/or cyclic mobility effects were considered during the analysis. For the FE analyses, OpenSees (Open System for Earthquake
Engineering Simulation) framework was adopted. 相似文献
67.
We propose a simple pressure test that can be used in the field to determine the effective permeability of existing wellbores.
Such tests are motivated by the need to understand and quantify leakage risks associated with geological storage of CO2 in mature sedimentary basins. If CO2 is injected into a deep geological formation, and the resulting CO2 plume encounters a wellbore, leakage may occur through various pathways in the “disturbed zone” surrounding the well casing.
The effective permeability of this composite zone, on the outside of the well casing, is an important parameter for models
of leakage. However, the data that exist on this key parameter do not exist in the open literature, and therefore specific
field tests need to be done in order to reduce the uncertainty inherent in the leakage estimates. The test designed and analyzed
herein is designed to measure effective wellbore permeability within a low-permeability caprock, bounded above and below by
permeable reservoirs, by pressurizing the reservoir below and measuring the response in the reservoir above. Alternatively,
a modified test can be performed within the caprock without directly contacting the reservoirs above and below. We use numerical
simulation to relate pressure response to effective well permeability and then evaluate the range of detection of the effective
permeability based on instrument measurement error and limits on fracture pressure. These results can guide field experiments
associated with site characterization and leakage analysis. 相似文献
68.
Natural radioactivity in sediment of Wei River,China 总被引:1,自引:0,他引:1
The concentrations of natural radionuclides in sediment of Wei River of China were measured using γ-ray spectrometry with
the aim of estimating the radiation hazard as establishing a database for radioactivity levels of river sediment of China.
The activity concentrations of 226Ra, 232Th and 40K in sediment samples ranged from 10.4 to 39.9 Bq kg−1, 15.3 to 54.8 Bq kg−1 and 514.8 to 1,175.5 Bq kg−1, respectively. The concentrations of these radionuclides were compared with the typical world values and the average activities
of Chinese soil and Shaanxi soil. Radium equivalent activity (Raeq), external hazard index (H
ex) and representative level index (I
γr) were calculated for the samples to assess the radiation hazards arising due to the use of these sediment samples in the
construction of dwellings. All the sediment samples have Raeq lower than the limit of 370 Bq kg−1, H
ex less than unity and I
γr close to 1 Bq kg−1. The overall mean outdoor terrestrial gamma dose rate is 64.8 nGy h−1 and the corresponding outdoor annual effective dose is 0.079 mSv. None of the studied location is considered a radiological
risk and sediment can be safely used in construction. 相似文献
69.
Atlas of karst area based on Web GIS technology 总被引:1,自引:0,他引:1
Leszek Litwin 《Environmental Geology》2008,54(5):1029-1036
70.
Development of a 3D GIS and its application to karst areas 总被引:1,自引:0,他引:1
There is a growing interest in modeling and analyzing karst phenomena in three dimensions. This paper integrates geology,
groundwater hydrology, geographic information system (GIS), database management system (DBMS), visualization and data mining
to study karst features in Huaibei, China. The 3D geo-objects retrieved from the karst area are analyzed and mapped into different
abstract levels. The spatial relationships among the objects are constructed by a dual-linker. The shapes of the 3D objects
and the topological models with attributes are stored and maintained in the DBMS. Spatial analysis was then used to integrate
the data in the DBMS and the 3D model to form a virtual reality (VR) to provide analytical functions such as distribution
analysis, correlation query, and probability assessment. The research successfully implements 3D modeling and analyses in
the karst area, and meanwhile provides an efficient tool for government policy-makers to set out restrictions on water resource
development in the area. 相似文献