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1.
Richard R. Parizek 《Environmental Geology》2007,51(5):731-735
Methods exist to obtain “new sources of water.” Examples include: (1) capturing and enhancing stormwater recharge and retention
within diffuse-flow portions of karst and other aquifers; (2) recycling and reuse of waste water; (3) reducing evapotranspiration
and rejected recharge; and (4) ameliorating atmospheric acid deposition through use of alkaline groundwater. These little
used management methods have immense potential to sustain future water demands. Full utilization of “new” and traditional
water resources requires an understanding of the hydrogeologic framework of karstic aquifers. Reliable conceptual, numerical
flow and transport models are needed to help evaluate, select, and design viable water management options. Three such simulation
examples are provided together with a discussion of Penn State’s Wastewater reuse project where recharge approaches 3.785 × 109l/year 相似文献
2.
Groundwater is a very important natural resource in Khanyounis Governorate (the study area) for water supply and development.
Historically, the exploitation of aquifers in Khanyounis Governorate has been undertaken without proper concern for environmental
impact. In view of the importance of quality groundwater, it might be expected that aquifer protection to prevent groundwater
quality deterioration would have received due attention. In the long term, however, protection of groundwater resources is
of direct practical importance because, once pollution of groundwater has been allowed to occur, the scale and persistence
of such pollution makes restoration technically difficult and costly. In order to maintain basin aquifer as a source of water
for the area, it is necessary to find out, whether certain locations in this groundwater basin are susceptible to receive
and transmit contamination. This study aims to: (1) assess the vulnerability of the aquifer to contamination in Khanyounis
governorate, (2) find out the groundwater vulnerable zones to contamination in the aquifer of the study area, and (3) provide
a spatial analysis of the parameters and conditions under which groundwater may become contaminate. To achieve that, DRASTIC
model within geographic information system (GIS) environment was applied. The model uses seven environmental parameters: depth
of water table, net recharge, aquifer media, soil media, topography, impact of vadose zone, and hydraulic conductivity to
evaluate aquifer vulnerability. Based on this model and by using ArcGIS 9.3 software, an attempt was made to create vulnerability
maps for the study area. According to the DRASTIC model index, the study has shown that in the western part of the study area
the vulnerability to contamination ranges between high and very high due to the relatively shallow water table with moderate
to high recharge potential, and permeable soils. To the east of the previous part and in the south-eastern part, vulnerability
to contamination is moderate. In the central and the eastern part, vulnerability to contamination is low due to depth of water
table. Vulnerability analysis of the DRASTIC Model indicates that the highest risk of contamination of groundwater in the
study area originates from the soil media. The impact of vadose zone, depth to water level, and hydraulic conductivity imply
moderate risks of contamination, while net recharge, aquifer media, and topography impose a low risk of aquifer contamination.
The coefficient of variation indicates that a high contribution to the variation of vulnerability index is made by the topography.
Moderate contribution is made by the depth to water level, and net recharge, while impact of vadose zone, hydraulic conductivity,
soil media, and Aquifer media are the least variable parameters. The low variability of the parameters implies a smaller contribution
to the variation of the vulnerability index across the study area. Moreover, the “effective” weights of the DRASTIC parameters
obtained in this study exhibited some deviation from that of the “theoretical” weights. Soil media and the impact of vadose
zone were the most effective parameters in the vulnerability assessment because their mean “effective” weights were higher
than their respective “theoretical” weights. The depth of water table showed that both “effective” and “theoretical” weights
were equal. The rest of the parameters exhibit lower “effective” weights compared with the “theoretical” weights. This explains
the importance of soil media and vadose layers in the DRASTIC model. Therefore, it is important to get the accurate and detailed
information of these two specific parameters. The GIS technique has provided an efficient environment for analysis and high
capabilities of handling large spatial data. Considering these results, DRASTIC model highlights as a useful tool that can
be used by national authorities and decision makers especially in the agricultural areas applying chemicals and pesticides
which are most likely to contaminate groundwater resources. 相似文献
3.
Igor Jemcov 《Environmental Geology》2007,51(5):767-773
The management of groundwater flow systems in karst regions appears, at present, to be the most important procedure for solving
water deficiency problems during periods of low rainfall. Faced with a lack of data for characterizing the water supply potential
of karst aquifers, analyses of spring hydrographs may provide valuable indirect information regarding the structure of karst
hydrogeological systems. To estimate the optimal exploitation capacities of karstic sources, a stochastic-conceptual approach
was applied in case studies from the Serbian karst. Water supply potentials were initially evaluated on the basis of groundwater
budgets. Further steps towards defining optimal “exploitable” regimes included analyses of storage changes in karst water
reservoirs under natural conditions and calculation of the potential expansion of currently tapped sources. The results obtained
through these analyses are a significant contribution to feasibility studies and aid in the avoidance of problems of overexploitation. 相似文献
4.
Hydrochemical framework of the aquifer in and around East Kolkata Wetlands,West Bengal,India 总被引:1,自引:0,他引:1
The area lies between Hugli river in the northwest and Bidyadhari river in the east and includes the East Kolkata Wetlands.
The East Kolkata Wetlands is included in the List of Wetlands of International Importance (“Ramsar List”), as per the Convention
on Wetlands signed in Ramsar, Iran, in 1971. This wetland has been declared as a Ramsar site on the 19th August 2002 (Ramsar
site no. 1208) and therefore has acquired an international status. The area is a part of the lower deltaic plain of the Bhagirathi–Ganga
river system and is generally flat in nature. The sub-surface geology of the area is completely blanketed by the Quaternary
fluviatile sediments comprising a succession of clay, silty clay, sand and sand mixed with occasional gravel. The Quaternary
aquifer is sandwiched between two clay sequences. The confined aquifer is made up of moderately well sorted sand and reflects
fluviatile environment of deposition. The regional groundwater flow direction is from east to west. Detailed geochemical investigations
of 40 groundwater samples along with statistical analysis (for example, correlation and principal component analysis) on these
chemical data reveal: (i) four types of groundwater quality, for example, good, poor, very poor and water unsuitable for drinking
purpose, (ii) four hydrochemical facies which may be assigned to three broad types such as “fresh”, “blended”, and “brackish”
waters, (iii) the evolution of the “blended” water is possibly due to hydraulic mixing of “fresh” and “brackish” waters within
the aquifer matrix and/or in well mixing, and (iv) absence of Na–Cl facies indicates continuous flushing of the aquifer. 相似文献
5.
Hydrogeological conditions and quality of ground waters in northern Banat,Pannonian basin 总被引:1,自引:0,他引:1
Geological relationships, hydrogeology and chemical composition of ground water in northern Banat were studied through the
period 2000–2004 using the available background data from published and unpublished sources. Northern Banat is the extreme
northeastern part of the Republic of Serbia and a geotectonic part of the vast Pannonian depression. The source of domestic
and industrial water supply is only groundwater from artesian and subartesian aquifers of Lower Pleistocene (Q11) and Upper Pleistocene (Pl32) sand deposits. The ground water, “peculiar” in chemical composition, is the only source of drinking water in the arid area.
A notable variation in the chemical composition of artesian waters within the same geotectonic unit (Pannonian basin), abstracted
for municipal water supplies of Kikinda, Novi Knezevac and Djala, has attracted attention of these authors. Our paper attempts
to interpret the variation in the chemical composition of ground water and the cause of the variation by the interaction of
ground water and rocks forming the aquifers on the case example of the water supply sources for the three mentioned towns.
With respect to the depth and lithology of the aquifers, we interpret the varied chemical compositions of waters in the mentioned
sources as a consequence of natural factors (geological environment), geological relationships and hydrogeological conditions. 相似文献
6.
Hydrochemistry and Classification of Groundwater Resources of Ishwardi Municipal Area,Pabna District,Bangladesh 总被引:2,自引:0,他引:2
Golzar Hossain M. Farhad Howladar Lutfun Nessa Syed Samsuddin Ahmed Chowdhury Quamruzzaman 《Geotechnical and Geological Engineering》2010,28(5):671-679
The chemical property of groundwater depends largely on the mineralogical composition of the rocks through which the water
has moved and the rate of movement and these characteristics of surface water depend on organic and inorganic reactions, industrial
effluents, rainfall and temperature etc. The underground water tends to contain more dissolved materials than those in surface
water because of their more intimate and longer contact with organic materials of soil and rock particles. The groundwater
of the studied area is dominant of alkaline earth’s (Ca2+ and Mg2+) and weak acids (HCO3
−) which may be classified as Magnesium-Bicarbonate and Calcium Carbonate types. Genetically, the groundwater of the area belongs
to both “Normal Chloride” “Normal Sulphate” and “Normal Carbonate” to “Super Carbonate” group. Based on EC, SAR and RC, the
groundwater of the area varies from good–excellent quality for irrigation purposes with low alkali hazard and medium salinity
hazard. 相似文献
7.
D. V. Reddy P. Nagabhushanam M. R. Rao D. S. Mitra B. M. Tripati S. K. Sinha B. Bhadu 《Journal of the Geological Society of India》2011,77(3):239-242
The Oil and Natural Gas Corporation Limited (ONGC), India, embarked upon exploration and exploitation of deep groundwater
under the project named as “Saraswati” in arid Thar desert, Rajasthan, with a societal mission of providing water to the local
people and cattle. A 555 m deep well drilled by the ONGC near Jaisalmer town in 2006 encountered a potential aquifer at a
depth of 450–500 m. Radiocarbon dating of this well water indicated paleorecharge to be >40,000 yr BP (uncorrected) (Before
Present with respect to 1950 AD), while the medium depth (∼200 m) well waters around that area showed an age range of ∼9,000
to 17,000 yr BP (uncorrected). These waters represent pre-Saraswati era recharge, because the mighty Saraswati flowed in this
region between 7000–4000 yr BP. The stable isotope (δD and δ18O) and Total Dissolved Solids (TDS) data of these waters clearly indicated absence of communication between the two aquifers
(deep and medium depth). However, the extension of this deep aquifer needs to be determined. 相似文献
8.
Tunisian Chott’s region is one of the most productive artesian basins in Tunisia. It is located in the southwestern part of
the country, and its groundwater resources are developed for water supply and irrigation. The chemical composition of the
water is strongly influenced by the interaction with the basinal sediments and by hydrologic characteristics such as the flow
pattern and time of residence. The system is composed of an upper unconfined “Plio-Quaternary” aquifer with a varying thickness
of 20–200 m, an intermediate confined/unconfined “Complex Terminal” aquifer about 100 m in thickness and a deeper “Continental
Intercalaire” aquifer about 150 m in thickness separated by thick clay and marl layers. The dissolution of evaporites and
carbonates explains part of the contained Na+, Ca2+, Mg2+, K+, SO42− and Cl-, but other processes, such carbonate precipitation, also contributes to the water composition. The stable isotope composition
of waters establishes that the deep groundwater (depleted as compared to present corresponding local rainfall) is ancient
water recharged probably during the late Pleistocene and the early Holocene periods. The relatively recent water in the Plio-Quaternary
aquifer is composed of mixed waters resulting presumably from upward leakage from the deeper groundwater. 相似文献
9.
This paper describes the research carried out in a karst aquifer located in Soria, Spain. The system presents considerable
good-quality water resources, yielding a series of springs which constitute a “Natural Monument”. An integral study of the
hydrological cycle is presented in order to characterize the hydrodynamic behavior of the aquifer. Research combines conventional
geological and hydrogeological approaches with more innovative techniques such as speleo-diving. On the basis of relatively
little available data, quantitative results are obtained. These include estimations on porosity, hydraulic conductivity, transmissivity,
and groundwater renewal rate and aquifer reserves. A vulnerability assessment is carried out to evaluate the potential effects
of overpumping. This is followed by a proposal for sustainable aquifer management. Since aquifers such as the one in this
study are frequently found, this methodology could be successfully extrapolated to other cases. 相似文献
10.
Marleen Coetsiers Petra Blaser Kristine Martens Kristine Walraevens 《Environmental Geology》2009,57(5):1155-1168
Aquifers from the same typology can have strongly different groundwater chemistry. Deducing the groundwater quality of less
well-characterized aquifers from well-documented aquifers belonging to the same typology should be done with great reserve,
and can only be considered as a preliminary approach. In the EU’s 6th FP BRIDGE project “Background cRiteria for the IDentification
of Groundwater thrEsholds”, a methodology for the derivation of threshold values (TV) for groundwater bodies is proposed.
This methodology is tested on four aquifers in Flanders of the sand and gravel typology. The methodology works well for all
but the Ledo-Paniselian aquifer, where the subdivision into a fresh and saline part is disproved, as a gradual natural transition
from fresh to saline conditions in the aquifer is observed. The 90 percentile is proposed as natural background level (NBL)
for the unconfined Pleistocene deposits, ascribing the outliers to possible influence of pollution. For the Tertiary aquifers,
high values for different parameters have a natural origin and the 97.7 percentile is preferred as NBL. The methodology leads
to high TVs for parameters presenting low NBL, when compared to the standard used as a reference. This would allow for substantial
anthropogenic inputs of these parameters. 相似文献
11.
Hsueh-Yu Lu Tsung-Ren Peng Tsung-Kwei Liu Chung-Ho Wang Chih-Chao Huang 《Environmental Geology》2006,50(6):885-898
This study was based on the analysis of isotopic compositions of hydrogen and oxygen in samples from precipitation, groundwater and stream water. In addition, parts of groundwater samples were dated by carbon-14 and tritium. These data are integrated to provide other views of the hydrologic cycle in the Hsinchu-Miaoli groundwater district. The groundwater district is principally composed of Pleistocene and Holocene aquifers. The Pleistocene aquifers are highly deformed by folding and faults into small sub-districts with areas of only tens of square kilometers. These aquifers are exclusively recharged by local precipitation. The Holocene aquifers cover narrow creek valleys, only tens of meters in thickness. The local meteoric water line (LMWL), constructed from rainfall samples in the Hsinchu Science Park, is described by the equation δD=8.02δ18O+10.16, which agrees with the global meteoric water line. In addition, the precipitation isotopic compositions can be categorized into two distinct end members: typhoon type and monsoon type. The groundwater isotopic compositions are perfectly located on an LMWL and can be considered a mixture of precipitations. Based on the mass balance of isotopic compositions of oxygen and hydrogen, infiltration is more active in the rainy season with depleted isotopic compositions. The amount of infiltration during May–September is roughly estimated to comprise at least 55% of the whole year’s recharge. The isotopic compositions of stream water are expressed by a regression equation: δD=7.61δ18O+9.62, which is similar to the LMWL. Although precipitation isotopic compositions are depleted during summer time, the isotopic compositions contrarily show an enriched trend in the upstream area. This is explained by the opposite altitude effect on isotopic compositions for typhoon-related precipitations. 相似文献
12.
Hani Serhal Daniel Bernard Jamal El Khattabi Bastin-Lacherez Sabine Isam Shahrour 《Environmental Geology》2009,57(7):1579-1592
Since 1975, Europe sets up its policy to limit the degradation and the pollution of the aquatic environments through 30 directives
and regulations. In the north of France, the nitrate concentrations measured in the groundwater exceed the water drinking
limit fixed at 50 mg/L by the European framework directive in the field of water (2000/60/EC). This high concentration is
due to intensive agriculture, industrialization and demographic growth. Several programs were launched in order to resolve
this situation: “Ferti-better” or the use of fertilizer in moderation and installation and amelioration of wastewater collect
and treatment systems. In order to estimate the influence of the anthropic activities on the quality of groundwater in the
“Artois-Picardy” basin, a preliminary validation on parcel and district scale were necessary. The impact of these programs
in the “Cambrai district” was evaluated using an integrated approach, which is based on the use of four numerical models:
AgriFlux, VS2DT, Modflow and MT3D. The results illustrate an improvement due to the “Ferti-Better” program initiated in 1990
and punctual degradation under urbanized areas. Predictions (2015) show a spatial evolution of nitrates concentration varying
with the thickness of unsaturated layer. The integrated model constitutes an efficient tool for predicting the evolution of
the groundwater quality. This approach is important to control the application of the new European laws in the water field. 相似文献
13.
Thirty-two groundwater samples collected from the Merguellil Wadi basin (central Tunisia) complemented by the Haouareb dam reservoir water samples have been isotopically analysed in order to investigate the implication of the reservoir water to recharging the aquifer, and also to infer the sources, relative ages and mixing processes in the aquifer system. Plots of the stable isotopes data against the local meteoric lines of Tunis-Carthage and Sfax indicate a strong implication of the dam water noticeable up to a distance of 6–7 km. A contribution as much as 80% of the pumped water has been evidenced using isotopic mass balance. In addition, poorly distinguished water clusters in the stable isotope plots, but clearly identified in the diagrams δ18O versus 3H and 3H versus 14C, indicate various water types related to sources and timing of recharge. The isotopic signatures of the dam accounting water, the “old” and “native” recharged waters, have been evidenced in relation to their geographical distribution and also to their radiogenic isotopes (3H and 14C) contents. In the south-western part of the aquifer, mixing process occurs between the dam reservoir water and both the “old” and “native” water components. 相似文献
14.
Evaluation of groundwater environment of Kathmandu Valley 总被引:1,自引:1,他引:0
Vishnu Prasad Pandey Saroj Kumar Chapagain Futaba Kazama 《Environmental Earth Sciences》2010,60(6):1329-1342
Kathmandu Valley aquifer in central Nepal is continuously under stress since the commencement of mechanized extraction of
groundwater resources in early 1970s. Many wells have been drilled in shallow and deep aquifers of the valley; and numerous
studies have been made in last four decades to understand the aquifers. However, up-to-date information on well inventory,
water extraction, water quality and overall situation of groundwater environment are not yet known in the absence of institutional
responsibility in groundwater management. This study attempts to evaluate current state of the groundwater environment considering
natural and social system together; to better understand origin of stresses, their state, expected impact and responses made/needed
to restore healthy groundwater environment. The analysis reveals increasing population density (3,150–4,680 persons/km2), urbanization (increase in urban population from 0.61 to 1.29 million) and increasing number of hotels due to tourism (23–62
hotels) during a decade are acting as driving forces to exceed groundwater extraction over recharge (extraction = 21.56 and
recharge = 9.6 million-cubic meter-a-year), decrease in groundwater levels (13–33 m during 1980–2000 and 1.38–7.5 m during
2000–2008), decline in well yield (4.97–36.17 l/s during mid-1980s to 1998) and deterioration in water quality. In the absence
of immediate management intervention with institutional responsibility for groundwater development, regulation and knowledgebase
management (i.e. to facilitate collection, integration and dissemination of knowledge); situation of groundwater environment
are expected to deteriorate further. Groundwater modeling approach may help to suggest appropriate management intervention
under current and expected future conditions. 相似文献
15.
Yvonne S. Anku Bruce Banoeng-Yakubo Daniel K. Asiedu Sandow M. Yidana 《Environmental Geology》2009,58(5):989-997
Hydrochemical data are presented for groundwater samples, collected from fractured aquifers in parts of northern Ghana. The
data was collected to assess the groundwater suitability for domestic and agricultural use. Results of the study reveal that
the pH of the groundwater in the area is slightly acidic to slightly alkaline. The electrical conductivity values, total dissolved
solids (TDS) values and calcium, magnesium and sodium concentrations in the groundwater are generally below the limit set
by the WHO for potable water supply. On the basis of activity diagrams, groundwater from the fractured aquifers appears to
be stable within the montmorillonite field, suggesting weathering of silicate minerals. An inverse distance weighting interpolator
with a power of 2 was applied to the data points to produce prediction maps for nitrate and fluoride. The distribution maps
show the presence of high nitrate concentrations (50–194 mg/l) in some of the boreholes in the western part of the study area
indicating anthropogenic impact on the groundwater. Elevated fluoride level (1.5–4 mg/l), higher than the WHO allowable fluoride
concentration of 1.5, is recorded in the groundwater underlying the northeastern part of the study area, more specifically
Bongo and its surrounding communities of the Upper East region. Results of this study suggest that groundwater from the fractured
aquifers in the area exhibit low sodicity–low salinity (S1–C1), low sodicity–medium salinity (S1–C2) characteristics [United
States Salinity Laboratory (USSL) classification scheme]. All data points from this study plot within the ‘Excellent to good’
category on a Wilcox diagram. Groundwater in this area thus appears to provide irrigation water of excellent quality. The
hydrochemical results indicate that, although nitrate and fluoride concentrations in some boreholes are high, the groundwater
in the study area, based on the parameters analyzed, is chemically potable and suitable for domestic and agricultural purposes. 相似文献
16.
The degradation of groundwater quality, which has been noted in the recent years, is closely connected to the intensification
of agriculture, the unreasonable use of chemical fertilizers and the excess consumption of large volumes of irrigation water.
In the hilly region of central Thessaly in Greece, which suffers the consequences of intense agricultural use, a hydrogeological
study is carried out, taking groundwater samples from springs and boreholes in the Neogene aquifers. The aim of this study
is the investigation of irrigation management, water quality and suitability for various uses (water supply, irrigation),
the degradation degree and the spatial distribution of pollutants using GIS. The following hydrochemical types prevail in
the groundwater of the study area: Ca–Mg–HCO3, Mg–Ca–Na–HCO3 and Na–HCO3. In the above shallow aquifers, especially high values of NO3
− (31.7–299.0), NH4
+ (0.12–1.11), NO2
− (0.018–0.109), PO4
3− (0.07–0.55), SO4
2− (47.5–146.5) and Cl− (24.8–146.5) are found, particularly near inhabited areas (values are in mg L−1). The water of shallow aquifers is considered unsuitable for human use due to their high polluting load, while the water
of the deeper aquifers is suitable for human consumption. Regarding water suitability for irrigation, the evaluation of SAR
(0.153–7.397) and EC (481–1,680 μS cm−1) resulted in classification category ‘C3S1’, indicating high salinity and low sodium water which can be used for irrigation
in most soils and crops with little to medium danger of development of exchangeable sodium and salinity. The statistical data
analysis, the factor analysis and the GIS application have brought out the vulnerable-problematic zones in chemical compounds
of nitrogen and phosphates. The groundwater quality degradation is localized and related exclusively to human activities.
Based on 2005 and 2008 estimates, the annual safe yield of the region’s aquifers were nearly 41.95 MCM. However, the existing
situation is that 6.37 MCM of water is over extracted from these aquifers. 相似文献
17.
Jin Zhang Jinyi Li Yanfeng Li Zongjin Ma 《International Journal of Earth Sciences》2009,98(6):1511-1527
The Cenozoic deformation of the Alxa Block resulted directly from the evolution of the northern Qinghai-Tibetan Plateau. However,
many data show that the deformation occurred only in the Middle-Late Miocene. Our studies show that the Altyn Tagh fault did
not pass through the Alxa Block; on the contrary it went along the southern boundary of the Jintai-Huahai Basin, linking with
the Helishan—southern Longshoushan fault. Due to important tectonic events in the northern Qinghai-Tibetan plateau during
the Middle-Late Miocene time, the northern plateau underwent rapid uplift and the plateau compressed the Hexi Corridor Region,
resulting in a change from NS-trending to EW-trending structures in the Jinta-Huahai basin, and in the development of compressive
structures in the Beishan. The southern Alxa fault underwent right lateral movement, and in the northern and central parts
of the block, NS-trending Tertiary extensional structures formed. These basins controlled by Tertiary faults are similar to
basins developed by lateral extrusion with a strong foreland and weak limited boundaries. The authors suggest that a regional
“conjugate” fault system resulted from nearly NS-trending compression from the Qinghai-Tibetan Plateau during the Miocene
and Pliocene in the Alxa Block and southern Mongolia. And due to the control of early structures in these regions, most brittle
faults reactivated earlier ductile faults; NW–SE faults along the Altai Mountain and NE–SW faults to the southeast in Mongolia
consist of a “conjugate” fault system to the north. The Altyn Tagh fault and southern Helishan-Longshoushan fault comprise
a “conjugate” fault system to the south. The Beishan and Jinta-Huahai Basin occupied the convergent area between these two
sets of faults; the compression controlled the Tertiary deposition and led to the development of the Cenozoic Jinta-Huahai
Basin. The Alxa Block bounded by these two sets of faults moved eastwards, which resulted in the development of Cenozoic compressive
structures to the west of Helan Shan, and superimposed early ductile shear zones along the northeastern and southwestern boundaries
of the Alxa Block respectively. This model could explain the Cenozoic deformation occurring in and around the Alxa region. 相似文献
18.
Hualing Wei Nianqiao Fang Xuan Ding Lanshi Nie Xiuming Liu 《Frontiers of Earth Science》2008,2(2):162-169
This paper presents pelagic records of planktic foraminifera, as well as data of stable isotope stratigraphy and carbonate
stratigraphy since 3.5 Ma B.P. from site ODP758 in the Ninetyeast Ridge of the Indian Ocean. Based on these data, manifestations
and related mechanisms of major tectonic and environmental events such as the rapid uplift of the Himalaya Mountains, “middle
Pleistocene climatic transition” and “mid-Brunhes dissolution event” in the region are discussed. According to the analysis
and comparison of various indices and changes in terms of foraminifera assemblage, paleotemperature, paleosalinity and themocline
from site ODP758, the authors deduce that the paleoclimatic changes might correlate with the mid-Pleistocene transition at
1.4–1.7 Ma B.P. The changes of CaCO3, mass accumulation rates (MAR) of CaCO3 and non- CaCO3 MAR indicate that the loaded terrigenous sediments increased at 1.7 Ma, which is in agreement with the uplift history of
the Qinghai-Tibet plateau as shown by the available data. The last two changes coincide with the uplift of the Qinghai-Tibet
plateau, hence they are called “Qinghai-Tibet movement” (1.7 Ma), and the “Kunlun-Yellow River movement” (1.2–0.6 Ma). The
changes of the CaCO3 content, coarse fraction (> 150 μm) content and planktonic foraminifera biostratigraphy show that strong dissolution of abyssal
CaCO3 occurred in the study region during 0.5–0.4 Ma. The event was consistent with the “mid-Brunhes dissolution event” in the
sedimentary records of the Atlantic Ocean, Pacific Ocean, Indian Ocean and Nansha sea area of the South China Sea.
__________
Translated from Geological Bulletin of China, 2007, 26(12): 1627–1632 [译自: 地质通报] 相似文献
19.
Groundwater pollution risk mapping for the Eocene aquifer of the Oum Er-Rabia basin, Morocco 总被引:2,自引:0,他引:2
Said Ettazarini 《Environmental Geology》2006,51(3):341-347
Sustainable development requires the management and preservation of water resources indispensable for all human activities. When groundwater constitutes the main water resource, vulnerability maps therefore are an important tool for identifying zones of high pollution risk and taking preventive measures in potential pollution sites. The vulnerability assessment for the Eocene aquifer in the Moroccan basin of Oum Er-Rabia is based on the DRASTIC method that uses seven parameters summarizing climatic, geological, and hydrogeological conditions controlling the seepage of pollutant substances to groundwater. Vulnerability maps were produced by using GIS techniques and applying the “generic” and “agricultural” models according to the DRASTIC charter. Resulting maps revealed that the aquifer is highly vulnerable in the western part of the basin and areas being under high contamination risk are more extensive when the “agricultural” model was applied. 相似文献
20.
M. Draoui J. Vias B. Andreo K. Targuisti J. Stitou El Messari 《Environmental Geology》2008,54(3):455-463
This paper presents the results of a comparative study relating to the application of four vulnerability mapping methods,
GOD, AVI, DRASTIC and SINTACS, in a pilot detritic aquifer situated in NW Morocco, known as the Martil–Alila aquifer. The
principal objective of this work is to determine the most suitable such methods for this aquifer type within a Mediterranean
context, and to show the effect of the rainfall variations that are characteristic of the Mediterranean climate on the degree
of vulnerability. The methods applied distinguish five classes of vulnerability, these being irregularly divided up in space,
with the division varying according to the method in question. The vulnerability maps obtained by the different methods strongly
suggest that the eastern half of the aquifer is more vulnerable to contamination than the western half, for all hydrological
situations. The effect of climatic conditions on the degree of vulnerability is well represented by the DRASTIC, according
to which the aquifer is moderately to strongly vulnerable during humid hydrological years and weakly to moderately vulnerable
during dry ones. For the other methods, this climatic effect is limited to the area occupied by the two predominant classes
(“High” and “Low” for GOD and “High” and “Moderate” for SINTACS) while it is null for AVI. In conclusion, DRASTIC appears
the most suitable for mapping the vulnerability to contamination of Mediterranean coastal detritic aquifers such as the Martil–Alila
aquifer. 相似文献