共查询到20条相似文献,搜索用时 109 毫秒
1.
Correlation between geology and radon levels in groundwater, soil and indoor air in Bhilangana Valley, Garhwal Himalaya, India 总被引:2,自引:1,他引:2
Radon concentrations were measured in soil, air and groundwater in Bhilangana Valley, Garhwal Himalaya, India by using an
LR-115 plastic track detector and radon emanometer. Radon concentrations were found to vary from 1 KBq/m3 to 57 KBq/m3 in soil , 5 Bq/l to 887 Bq/l in water and 95 Bq/m3 to 208 Bq/m3 in air. The recorded values are quite high due to associated uranium mineralization in the area. Radon concentration was
also found to depend on the tectonic structure and geology of the area.
Received: 22 July 1996 · Accepted: 8 January 1997 相似文献
2.
Radon measurements in soil and groundwater (springs, thermal springs and handpumps) were made in a variety of lithological
units including major thrusts between Mandi and Manali in Himachal Himalaya. Analysis of radon data in light of lithological
controls and influence of deep-seated thrusts has been made to elucidate the causative factors for anomalous emanation of
radon. The lithological types include banded gneisses, schists, quartzite, granite, phyllites, volcanics and mylonites. The
low-grade metasedimentries of Shali and Dharamsala generally show low and narrow range of radon concentration in water (5.6–13.4 Bq/l)
as well as in soil (1.8–3.2 kBq/m3) except for the samples related to thrusts. On the other hand, sheared and deformed rocks of Chail and Jutogh show moderate
radon content (average 5.03 kBq/m3, range 2.9–11.1 kBq/m3) in soil. However, the groundwater radon concentration shows wide variation in different types of sources (2.1–80.8 Bq/l).
The quartzite and volcanic rocks of Rampur formation in this area present as a window separated by Chail thrust. Radon emanations
on these rock types are relatively high (6.3–68.1 Bq/l in water and 5.5–15.9 kBq/m3 in soil) and are exceptionally high in samples that are related to uranium mineralization, deep-seated thrusts and hot springs
(13.5–653.5 Bq/l). It is generally observed that anomalous high radon content is associated with mineralization, deeper source
and tectonic discontinuities. Whereas it is obvious that subsurface radioactive mineralization would facilitate enhanced radon
production, however, thrust plains provide easy pathways for escape of gases from the deeper sources. Shallow and deep sources
of the groundwater have contrasting radon content particularly in the deformed and metamorphosed rocks of Jutogh and Chail.
Shallow groundwater sources, mainly handpumps, have lower radon concentration due to limited superficial water circulation,
whereas deeper sources, mainly perennial springs, show higher radon content because of larger opportunity for water–rock interaction. 相似文献
3.
Najeeb. K. Md N. Vinayachandran Bijimol Jose Rahul Vashistha 《Journal of the Geological Society of India》2014,83(6):665-668
Radon is a naturally occurring colourless and odourless radioactive gas that is soluble in water and is the main source of radioactivity of groundwater. Use of radon contaminated groundwater increased the radon levels in the air, especially in poorly ventilated houses, which is hazardous to health. Ingestion of such water for quite long period may lead to stomach cancer. The drinking water standards proposed by the Bureau of Indian Standards (BIS) exclude the permissible concentration of radon in drinking water. The US Environmental Protection Agency (USEPA) in 1991 proposed a Maximum Concentration Level (MCL) of 11.1 Bq/l for public water supply. The water samples from the bore wells in Tumkur district of Karnataka show radon concentrations in the range of 5 to 250 Bq/l. Ninety percentages of the samples show radon levels above the permissible limit as per USEPA. The spatial variation and geological control over radon concentration in groundwater in the area and sampling sensitivity are discussed here. The study was conducted during March 2012. 相似文献
4.
Groundwater nitrate pollution in an alluvium aquifer, Eskişehir urban area and its vicinity, Turkey 总被引:1,自引:0,他引:1
A large amount of the water requirement (municipal, industrial, etc.) of Eskişehir city, Turkey, is supplied from groundwater
via wells in the urban area. The groundwater in the Eskişehir Plain alluvium has been polluted by municipal and industrial
wastewater, and agricultural activities. The nitrate concentrations at nine sampling points on Porsuk River, the main water
course in the plain, ranged from 1.5 to 63.3 mg/l during the period from July 1986 to August 1988. In the same period, the
nitrate concentrations measured in water from 51 wells ranged between 2.2–257.0 mg/l. The nitrate content of the groundwater
samples was 34.2% above 45 mg/l, the upper limit for nitrate in drinking water standards. High nitrate levels were observed
in water from wells in the central and eastern parts of the urban area. The nitrate content of the well water is subject to
seasonal fluctuation. In general, low nitrate concentrations were observed in wet seasons, and high ones in dry seasons.
Received: 16 April 1996 · Accepted: 2 October 1996 相似文献
5.
Radon in Himalayan springs: a geohydrological control 总被引:3,自引:0,他引:3
This paper presents the results of radon measurements in springs of the Himalayan region by using radon emanometry technique.
The radon was measured in different springs, draining from different geohydrological setups, and from stream water in order
to find the geohydrological control over radon concentration in groundwater emanating in the form of spring. The radon values
were found to vary from 0.4 Bq/l to 887 Bq/l, being observed lowest for a turbulent stream and highest for the spring. The
radon values were recorded highest in the springs draining through gneiss, granite, mylonite, etc. Radon concentrations have
been related with four spring types viz. fracture-joint related spring, fault-lineament related spring, fluvial related spring
and colluvial related spring, showing geohydrological characteristics of the rocks through which they are emanating. The high
radon concentration in fracture-joint and fault-lineament spring is related to increased ratio of rock surface area to water
volume and uranium mineralisation in the shear zones present in the close vicinity of fault and thrust. The low concentration
of radon in fluvial and colluvial springs is possibly because of high transmissivity and turbulent flow within such deposits
leading to natural de-emanation of gases.
Received: 6 January 1998 · Accepted 11 May 1999 相似文献
6.
Heavy metal distribution and environmental status of Doon Valley soils, Outer Himalaya, India 总被引:1,自引:0,他引:1
K. K. Purohit P. K. Mukherjee P. P. Khanna N. K. Saini M. S. Rathi 《Environmental Geology》2001,40(6):716-724
Doon Valley is surrounded by two major river systems (Ganga and Yamuna) on either side, with a water divide passing nearly
across the centre of the valley, and is sandwiched between two mountain ranges in the fragile ecological systems of the Himalayan
foothills. In total 398 soil samples were collected from the valley in a grid pattern (∼1 sample per 2 km2) and investigated for their heavy metal (Cr, Cu, Ni, Pb and Zn) abundances that are environmentally sensitive. Comparison
of the heavy metal abundances with the contamination threshold values (CTV) revealed that most of these elemental abundances
in Doon Valley soils fall well within the range of the uncontaminated to slightly contaminated category. In the case of Cr
and Ni, a sizeable number of samples exceeded the CTV (250 and 100 mg kg–1 respectively) with an overall background value of 109 and 52 mg kg–1 respectively. Sites of high Cr and Ni mostly occur in the Ganga Catchment (GC) sector that includes even relatively undisturbed
forestland. The source of this contamination is attributed to geological factors which indicate contribution from the mafic
volcanics of the Lesser Himalaya. This is also consistent with the distribution pattern of Mn and Fe, though their abundance
levels are not alarming. The background concentration of Pb is low (22 mg kg–1) in Doon Valley soils; however, signs of gradual Pb contamination are palpable in and around the centre of the Dehra Dun
city and along the highways. Aluminium normalized heavy metal ratios were found to exhibit narrow variability in the case
of Cu, Ni and Cr and had good correlation with Al, indicating their affinity and association with the clay minerals. On the
other hand, Pb and Zn seem to be associated with non-silicate sources.
Received: 7 January 2000 · Accepted: 30 July 2000 相似文献
7.
Geochemistry of granites and metasediments of the urban area of Vila Real (northern Portugal) and correlative radon risk 总被引:2,自引:2,他引:0
M. E. P. Gomes L. J. P. F. Neves F. Coelho A. Carvalho M. Sousa A. J. S. C. Pereira 《Environmental Earth Sciences》2011,64(2):497-502
Radon concentration was evaluated in dwellings of the urban area of Vila Real (Northern Portugal). The area is mainly composed
of Hercynian granites and Cambrian metasediments, and CR-39 passive detectors (n = 112) were used for the purpose. The results obtained in winter conditions suggest that the most productive geological unit
is the Hercynian granite G1 (geometric mean of 364 Bq/m3), while Cambrian metasediments of the Douro Group show the lowest average indoor radon concentration (236 Bq/m3). The geological, geochemical and radiological data obtained suggest that the most effective control on the radon concentrations
of the area is related with the uranium content of the rocks; indeed, the highest contents were observed in granite G1 (21 ppm)
and the lowest in the metasediments (3 ppm). This is also confirmed by the results obtained for groundwater, where granites
present the highest concentrations of dissolved radon (up to 938 Bq/l), uranium (5–18 ppb) and gross α activities (0.47–0.92 Bq/l). No important radiometric anomalies were found in relation with geological structures such as
faults, veins and contacts, but a moderate increase of the uranium content can occur locally in such structures. Petrographic
observations and SEM studies show that uranium is mainly contained within the rock in heavy accessory minerals (apatite, zircon,
monazite, xenotime), which reduces radon emanation. Notwithstanding, due to the high U contents granites show a significant
potential to induce indoor radon concentrations in dwellings in excess of the recommended value of 400 Bq/m3. Overall, we can conclude that the region of Vila Real presents a moderate to high radon risk in dwellings and groundwater. 相似文献
8.
Predicting New Hampshire indoor radon concentrations from geologic information and other covariates 总被引:2,自引:2,他引:0
Generalized geologic province information and data on house construction were used to predict indoor radon concentrations
in New Hampshire (NH). A mixed-effects regression model was used to predict the geometric mean (GM) short-term radon concentrations
in 259 NH towns. Bayesian methods were used to avoid over-fitting and to minimize the effects of small sample variation within
towns. Data from a random survey of short-term radon measurements, individual residence building characteristics, along with
geologic unit information, and average surface radium concentration by town, were variables used in the model. Predicted town
GM short-term indoor radon concentrations for detached houses with usable basements range from 34 Bq/m3 (1 pCi/l) to 558 Bq/m3 (15 pCi/l), with uncertainties of about 30%. A geologic province consisting of glacial deposits and marine sediments was
associated with significantly elevated radon levels, after adjustment for radium concentration and building type. Validation
and interpretation of results are discussed.
Received: 20 October 1997 · Accepted: 18 May 1998 相似文献
9.
Study of the radon concentrations in drinking water from three main cities of Shaanxi Province,China
This paper presents the results of radon concentration measurements in the drinking water from the municipal water supply system and private wells of Xian, Xianyang and Baoji city of Shaanxi province of China. The measurements were carried out on 38 samples. Radon levels in drinking water in Xian, Xianyang and Baoji were found to be 5.78, 13.04 and 15.01 k Bq m–3, respectively. The AM radon concentration of private well water from Xianyang and Baoji is 28.84 k Bq m–3 and 38.85 k Bq m–3, respectively, which is 2.56 times and 3.14 times as high as that of tap water radon, respectively. The radiation risk of radon in water would be due to degassing and not due to drinking water. The domestic use of showers, humidifiers, and cooking, washing up, laundering, etc. may lead to an additional increase of the radon concentration in the indoor air. The observed radon concentration in drinking water from three main cities of Shaanxi Province can contribute to a 4.86 to 32.63% increase in indoor radon concentration and can cause 0.068±0.016 mSv y–1 to 0.177±0.045 mSv y–1 extra annual effective dose to males, 0.060±0.014 mSv y–1 to 0.155±0.039 mSv y–1 to females. The mean annual effective dose equivalents to males and females of Xianyang and Baoji from well water account for 25.94 to 39.75% of environmental radon and radon daughters annual effective dose equivalents. The radon concentrations in the well water from Xianyang and Baoji will bring a definite additional risk to the population. 相似文献
10.
Geochemistry, genesis, and health implications of fluoriferous groundwaters in the upper regions of Ghana 总被引:9,自引:2,他引:9
The most appropriate and widely used source of drinking water for the populations of the upper regions of Ghana is groundwater.
In general, groundwater quality is acceptable except for some parts of the Bolgatanga and Bongo Districts, where there are
occurrences of elevated levels of natural groundwater fluoride. Concentrations of groundwater fluoride in excess of the World
Health Organization (WHO) maximum guideline value (1.5 mg/l) in the Bongo area have been known since 1978. However, the effect
of fluoride on people ingesting the water did not receive public and medical attention until October 1993, when health personnel
were asked to investigate the cause of stained teeth in school children. The investigation established that 62% of the total
population of school children in the Bongo area had dental fluorosis. Against this background, a study was initiated to understand
the geochemistry, genesis, and distribution of fluoride in relation to the geology of the area. Groundwater fluoride in the
upper regions ranges from 0.11 to 4.60 ppm, with the highest concentrations associated with the fluorine-enriched Bongo coarse-grained
hornblende granite and syenite suite. The source of groundwater fluoride within the Bongo granitoids is dissolution of the
mineral fluorite and dissolution of and anion exchange with micaceous minerals and their clay products. Applying the WHO recommended
guideline values for fluoride in drinking water reveals that 49% of wells in the area deliver water below the optimum level
of 0.5 mg/l F–; these populations are thus prone to dental caries. Twenty-eight percent of the wells fall within the optimum interval for
good dental health (0.5–1.5 mg/l F–). Twenty-three percent of the wells have concentrations above the recommended maximum guideline limit of 1.5 mg/l F–; this population is susceptible to dental and possibly skeletal fluorosis. Climatic conditions of the area suggest that the
individual water consumption is in the order of 3 to 4 l which is higher than the WHO estimate of 2 l/adult/day. In addition,
dietary intake for the upper region population is probably higher than WHO baseline values (0.2–0.5 mg/day). This implies
that a much higher population is susceptible to developing dental and skeletal fluorosis than originally suspected. Geochemical
symbol plot maps help geochemists understand factors controlling the distribution and uptake of fluoride in the upper regions,
but they are of minimal value to health officials responsible for planning epidemiological studies and dental health education
programs in the region. By casting fluoride data into contoured 'geochemical health-risk maps' using intake interval guidelines
more closely aligned to regional climatic and dietary conditions, health officals can better judge the impacts (regional and
population based) of fluoride on segments of the population, such as various sex and age groups.
Received: 11 March 1997 · Accepted: 17 June 1997 相似文献
11.
The arsenic concentration in 13 water samples from wells in the thin, alluvial aquifer of the Madison River Valley, Montana,
U.S.A. ranged from 26 to 150 μg/l. The Madison River, which originates in Yellowstone National Park, has a mean arsenic concentration
of 51 μg/l (σ=26 μg/l), based upon very limited sampling in the study area during the main irrigation period. Groundwater
arsenic concentration increases down the valley can be best correlated with the intensity of ditch irrigation in this semiarid
area. No other sources of dissolved arsenic as concentrated as that of the river water have been identified. Evaporative concentration
of river-derived irrigation water is believed to have been the overwhelming factor in the contamination of this shallow aquifer. 相似文献
12.
V. V. S. Gurunadha Rao R. L. Dhar T. Jayachand C. S. Khoker 《Environmental Geology》2000,39(10):1138-1146
Mathura oil refinery was commissioned during 1977 and effluent storage ponds were constructed at the same time. These storage
ponds receive wastewater from the refinery at a rate of 10000 m3/day. After treatment, waste water is discharged through a 3-km pipeline to a stream leading to the Yamuna river. The groundwater-monitoring
as well as water-quality monitoring was carried at 24 observation wells in the refinery site during 1997. The water quality
measurements indicated total dissolved chloride and sulphate concentration of native groundwater as 400 mg/l, whereas elevated
levels up to 600 mg/l were found at the wells close to polishing ponds. Thus combined transport of chloride and sulphate was
simulated in the mass transport model. A three-dimensional flow, pathlines and mass transport model of the aquifer system
were constructed to analyze the impact of seepage from polishing ponds contaminating the groundwater regime. The permeability
of aquifer varies between 1.5–2.5 m/day. The porosity of formation was assumed as 0.2. The constant head and constant concentration
boundaries were assigned to the nodes representing effluent storage ponds. Longitudinal dispersivity of 100 m, horizontal
transverse dispersivity of 10 m and vertical transverse dispersivity of 0.01 m were assumed. The mass transport model was
calibrated for 20 years by comparing total dissolved chloride and sulphate concentrations from 1997. The model predictions
indicate further migration of contaminants on the east of effluent ponds in future.
Received: 4 January 1999 · Accepted: 12 July 1999 相似文献
13.
Spatio-temporal variation in radon concentration in groundwater with respect to rock types: A case study from Chitradurga district,Karnataka 总被引:1,自引:0,他引:1
P. Ravikumar Deljo Davis Sharika Mathew R. K. Somashekar K. L. Prakash 《Journal of the Geological Society of India》2014,83(2):156-164
An attempt was made in the present study to delineate how the radon concentrations vary with respect to different geological formations and to evaluate annual effective dose exposure due to ingestion of radon. A total of 60 groundwater samples were collected from layered sequential aquifers in Chitradurga district having major rock types such as Bababudan Group, Charnockite, Chitradurga Group, Closepet granite, migmatites and granodiorite — tonalitic gneisses and Sargur Schist complex during pre-monsoon and post-season of the year 2011. Radon measurement was made using Durridge RAD-7 radon-in-air monitor, connected to RAD H2O accessory with closed loop aeration concept. In the present study, the radon activity ranged from 0 to 186.6 Bq/L and 0 to 150.6 Bq/L during pre- and post-monsoon seasons of the year 2011, with 56.67 % (17 samples) of samples during both the seasons exceeding the EPA’s MCL value of 11.1 Bq/L. The annual mean radon activity in the groundwater was higher in the area having Chitradurga rock group formations (78.1 Bq/L) followed by Sargur-Satyamangalam schist complex group (56.8 bq/L), migmatites and granodiorite — tonalitic Gneisses group (56.3 Bq/L), Closepet granite (42.7 Bq/L), Charnonkite (29.1 Bq/L) and Bababudan Group (22.2 Bq/L). It is inferred that radon concentration found to depend on the tectonic structure, geology of the area and on the presence of uranium minerals in these rocks. The annual effective dose resulting from radon in groundwater in the Chitradurga district were significantly lower than UNSCEAR and WHO recommended limit of 1 mSv/y. 相似文献
14.
Groundwater arsenic contamination in Manipur,one of the seven North-Eastern Hill states of India: a future danger 总被引:1,自引:0,他引:1
Dipankar Chakraborti E. Jayantakumar Singh Bhaskar Das Babar Ali Shah M. Amir Hossain Bishwajit Nayak Sad Ahamed N. Rajmuhon Singh 《Environmental Geology》2008,56(2):381-390
Manipur State, with a population of 2.29 million, is one of the seven North-Eastern Hill states in India, and is severely
affected by groundwater arsenic contamination. Manipur has nine districts out of which four are in Manipur Valley where 59%
of the people live on 10% of the land. These four districts are all arsenic contaminated. We analysed water samples from 628
tubewells for arsenic out of an expected total 2,014 tubewells in the Manipur Valley. Analyzed samples, 63.3%, contained >10 μg/l
of arsenic, 23.2% between 10 and 50 μg/l, and 40% >50 μg/l. The percentages of contaminated wells above 10 and 50 μg/l are
higher than in other arsenic affected states and countries of the Ganga–Meghna–Brahmaputra (GMB) Plain. Unlike on the GMB
plains, in Manipur there is no systematic relation between arsenic concentration and the depth of tubewells. The source of
arsenic in GMB Plain is sediments derived from the Himalaya and surrounding mountains. North-Eastern Hill states were formed
at late phase of Himalaya orogeny, and so it will be found in the future that groundwater arsenic contamination in the valleys
of other North-Eastern Hill states. Arsenic contaminated aquifers in Manipur Valley are mainly located within the Newer Alluvium.
In Manipur, the high rainfall and abundant surface water resources can be exploited to avoid repeating the mass arsenic poisoning
that has occurred on the GMB plains. 相似文献
15.
Appraisal of highly fluoride zones in groundwater of Kurmapalli watershed,Nalgonda district,Andhra Pradesh (India) 总被引:2,自引:0,他引:2
N. C. Mondal R. K. Prasad V. K. Saxena Y. Singh V. S. Singh 《Environmental Earth Sciences》2009,59(1):63-73
Fluoride (F) contamination study had been carried out to see its allocation in Kurmapalli watershed, Nalgonda district, Andhra
Pradesh, India. The study area is located about 60 km SE of Hyderabad city. The groundwater is the main source of water for
their living. The groundwater in villages and its surrounding are affected by fluoride contamination and consequently the
majority of the people living in these villages has health hazards and is facing fluorosis. The purpose of this study is to
identify the wells with high F, raise awareness in people, study the water chemistry, and also find out the source of F in
groundwater. A total of 32 groundwater samples were collected from different wells in both shallow aquifers and deeper fractures
zones during October 2004. The chemical analysis of groundwater has been done. Fluoride values vary from 0.7 to 19.0 mg/l.
It is noted that the maximum value (19.0 mg/l) is one of the highest values found in groundwater in India and 78% of the total
samples show F concentrations that exceeds the permissible limit value (1.5 mg/l). The highest value of F is found at Madanapur
bore well which is located at central part of the watershed. The F value of this bore well was monitored from October 2004
to October 2006. During this period the F concentration varies from 17.8 to 21.0 mg/l with mean 19.3 mg/l. There is no correlation
of F with chemical parameters except calcium. The Ca has shown inverse proportional with F. Water–rock interaction studies
were also carried out to understand the behavior of F in groundwater at prominent F affected areas. Rock samples were collected
and analyzed, and found their enrichment of F. The anthropogenic possibility of F is almost negligible. The rocks of this
area are enriched in F from 460 to 1,706 mg/kg. It is indicated that the rock–water interaction is the main source of F in
groundwater. The highest values of F are found in middle part of the region and are related to the occurrence of fluoride
rich rocks and their chemical kinetic behavior with groundwater. 相似文献
16.
J. Pacheco Luis Marín Armando Cabrera Birgit Steinich Oscar Escolero 《Environmental Geology》2001,40(6):708-715
The nitrate concentration in 12 water-supply wells were monitored for the period April 1992 to March 1993. Each water-supply
well was sampled once a month. The nitrate concentrations in the 12 wells ranged from 7 to 156 mg/l. Two water-supply wells
(Chacsinkin and Peto) showed concentrations that reached 3.5 times the maximum permissible limit for the Drinking Water Standard
(45 mg/l). A third water-supply well (Akil) exceeds the norm for 7 out of 12 months. The use of nitrogen-rich fertilizers
are responsible for high nitrate concentrations in groundwater in the southern part of Yucatan, Mexico where intensive agricultural
practices exist.
Received: 14 December 1999 · Accepted: 2 May 2000 相似文献
17.
P. Ravikumar R. K. Somashekar 《International Journal of Environmental Science and Technology》2014,11(2):493-508
The distribution of radon in ground and surface water samples in Sankey Tank and Mallathahalli Lake areas was determined using Durridge RAD-7 analyzer with RAD H2O accessory. The radiation dose received by an individual falling under different age groups (viz., 3 months; 1, 5, 10, 15 years and adult) depending upon their average annual water consumption rate was attempted. The mean radon activity in surface water of Sankey Tank and Mallathahalli Lake was 7.24 ± 1.48 and 11.43 ± 1.11 Bq/L, respectively. The average radon activities ranged from 11.6 ± 1.7 to 381.2 ± 2.0 Bq/L and 1.50 ± 0.83 to 18.9 ± 1.59 Bq/L, respectively, in 12 groundwater samples each around Sankey Tank and Mallathahalli Lake areas. Majority of the measured groundwater samples (viz., 100 % in Sankey Tank area and 75 % in Mallathahalli Lake area) showed mean radon values above the EPA’s maximum contaminant level of 11.1 Bq/L and only 66.67 % of samples in Sankey Tank area showed radon above the WHO and EU’s reference level of 100 Bq/L. The overall radiation dose due to radon emanating from water in the study area was increasing with increase in age and water consumption rates, but significantly lower than UNSCEAR and WHO recommended limit of 1 mSv/year except for few groundwater samples in Sankey Tank area (i.e., 0.92, 0.99 and 1.39 mSv/year). The radiation dose rate received by bronchial epithelium via inhalation was very high compared to that by stomach walls via ingestion. 相似文献
18.
It has been established that radon and its airborne decay products can present serious radiation hazards. A long term exposure
to high concentration of radon causes lung cancer. Besides, it is also known that out of the total radiation dose received
from natural and man-made sources, 60% of the dose is due to radon and its progeny. Taking this into account, an attempt has
been made to estimate radon concentration in dwellings in and around Guwahati using aluminium dosimeter cups with CR-39 plastic
detectors. Results of preliminary investigation presented in this paper show that the mean concentration is 21.31 Bq m − 3. 相似文献
19.
The aquifer system of the Upper Triassic Keuper Sandstone, an important source of drinking water in northern Bavaria, is
affected by elevated arsenic concentrations. Within the study area of 8000 km2, no evidence exists for any artificial source of arsenic. Data from about 500 deep water wells show that in approximately
160 wells arsenic concentrations are 10–150 μg/L. The regional distribution of arsenic in the groundwater shows that elevated
arsenic concentrations are probably related to specific lithofacies of the aquifers that contain more sediments of terrestrial
origin. Geochemical measurements on samples from four selected well cores show that arsenic has accumulated in the rocks.
This indigenous arsenic is the source of arsenic in the groundwater of certain facies of the middle unit of the Keuper Sandstone.
Received, June 1998 / Revised, January 1999, May 1999 / Accepted, June 1999 相似文献
20.
Irina Gaus 《Hydrogeology Journal》2000,8(2):218-229
Pesticides are a potential threat to the quality of extracted groundwater when the water-supply area is used for agricultural
activities. This problem is discussed for the water-supply area of Sint-Jansteen, The Netherlands, where measured pesticide
concentrations in the extracted water regularly exceed EU limits (0.1 μg/L). Groundwater samples taken from the aquifer within
the water-supply area show low contamination, but samples taken from the extracted water occasionally contain pesticides,
making the water inadequate for drinking-water purposes. The more intense contamination of the extracted water is caused by
the change in the natural groundwater flow pattern near the extraction wells. In this area, pesticide use cannot be avoided
easily, and an approach is given to differentiate pesticide use in the area according to expected travel time toward the wells
and the chemical characteristics of the pesticides. A groundwater flow model for the area is developed and the effects of
groundwater extraction on the natural flow pattern are evaluated. Using particle tracking, the travel-time zones are determined.
Combining these results and the degradation behavior of certain pesticides led to an optimal scheme to integrate agricultural
activities and groundwater extraction in the area. This is illustrated for five different types of pesticides (atrazine, simazine,
bentazone, MCPA, and mecoprop).
Received, October 1998/Revised, July 1999, September 1999/Accepted, November 1999 相似文献