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1.
To study arsenic(As) content and distribution patterns as well as the genesis of different kinds of water, especially the different sources of drinking water in Guanzhong Basin, Shaanxi province, China, 139 water samples were collected at 62 sampling points from wells of different depths, from hot springs, and rivers. The As content of these samples was measured by the intermittent flowhydride generation atomic fluorescence spectrometry method(HG-AFS). The As concentrations in the drinking water in Guanzhong Basin vary greatly(0.00–68.08 μg/L), and the As concentration of groundwater in southern Guanzhong Basin is different from that in the northern Guanzhong Basin. Even within the same location in southern Guanzhong Basin, the As concentrations at different depths vary greatly. As concentration of groundwater from the shallow wells(50 m deep, 0.56–3.87 μg/L) is much lower than from deep wells(110–360 m deep, 19.34–62.91 μg/L), whereas As concentration in water of any depth in northern Guanzhong Basin is 10 μg/L. Southern Guanzhong Basin is a newly discovered high-As groundwater area in China. The high-As groundwater is mainly distributed in areas between the Qinling Mountains and Weihe River; it has only been found at depths ranging from 110 to 360 m in confined aquifers, which store water in the Lishi and Wucheng Loess(Lower and Middle Pleistocene) in the southern Guanzhong Basin. As concentration of hot spring water is 6.47–11.94 μg/L; that of geothermal water between 1000 and 1500 m deep is 43.68–68.08 μg/L. The high-As well water at depths from 110 to 360 m in southern Guanzhong Basin has a very low fluorine(F) value, which is generally 0.10 mg/L. Otherwise, the hot springs of Lintong and Tangyu and the geothermal water in southern Guanzhong Basin have very high F values(8.07–14.96 mg/L). The results indicate that highAs groundwater in depths from 110 to 360 m is unlikely to have a direct relationship with the geothermal water in the same area. As concentration of all reservoirs and rivers(both contaminated and uncontaminated) in the Guanzhong Basin is 10 μg/L. This shows that pollution in the surface water is not the source of the high-As in the southern Guanzhong Basin. The partition boundaries of the high- and low-As groundwater area corresponds to the partition boundaries of the tectonic units in the Guanzhong Basin. This probably indicates that the high-As groundwater areas can be correlated to their geological underpinning and structural framework. In southern Guanzhong Basin, the main sources of drinking water for villages and small towns today are wells between 110–360 m deep. All of their As contents exceed the limit of the Chinese National Standard and the International Standard(10 μg/L) and so local residents should use other sources of clean water that are 50 m deep, instead of deep groundwater(110 to 360 m) for their drinking water supply.  相似文献   

2.
In this study, the concentration and spatial distribution of potentially toxic metals(PTMs), including arsenic(As), cadmium(Cd), chromium(Cr), lead(Pb), copper(Cu), iron(Fe), manganese(Mn), and magnesium(Mg) in 23 wells and drinking groundwater distribution networks of Rafsanjan, located in southeast Iran were evaluated. Moreover, the assessment of carcinogenic and non-carcinogenic risks was estimated by Monte Carlo simulation(MCS). The results showed that the concentrations of As and Pb in more than 99% and 23.46% of the study area, respectively, were higher than the maximum concentration level(10 μg/L). The mean concentration of other metals, including Cd, Cr, Cu, Fe, Mg, and Mn in all drinking water resources was within the WHO standard level. The mean hazard quotient(HQ) for As in the age group of children was 9.246 and adults 2.972, indicating high non-carcinogenic risk of As in the study area. The lifetime cancer risk(LTCR) of As was 1.36 E-3 for adults and 1.52 E-2 for children, indicating high non-carcinogenic risk of As. The level of HQ and LTCR for Pb in both age groups was in the acceptable range. The results of sensitivity analysis showed that the most effective variables were pollutant concentration and body weight(BW), respectively. Finally, it can be concluded that exposure to PTMs, especially As through drinking water in the study area can have significant effects on people’s health living in the area;therefore, it is necessary to treat and remove As from groundwater resources before drinking or using for domestic purpose.  相似文献   

3.
Background： Fluorine is an important element to human health. Overloading of fluorine may cause dental and/or skeletal fluorosis, while in fluorine deficiency distracts, fluoride drinking water supply or other methods of fluoridation may greatly reduce the ratio of dental caries of local residents. The benefit of drinking water fluoridation has been widely accepted as a public sanitation measure in most western countries, but in China it faces big challenges. Method： Investigation of oral health and fluorine level in drinking water, main food and urine in some big cities of China. Result and conclusion： （1） Fluorine content in drinking water in 70% of the whole research cities is lower than 0.3 mg/L, and in 90% of the research cities, it is lower than 0.5 mg/L. （2） Fluorine concentrations in main foodstuff of respective cities in China were low and did not have too much difference. （3） Drinking water was the main source of fluorine intake for Chinese residents. （4） With the data of the epidemiological research by NCOH in 1995, in the range of fluorine content in drinking water below 1.0 mg/L, the ratio of dental caries and DMFT decreases with the increase of fluorine concentration. The relation between fluorine concentration in drinking water and dental index did not have a good linear relationship.  相似文献   

4.
河西内陆河流域水资源及其动态变化   总被引：1，自引：0，他引：1  
The Qilian Mountains is the cradle of all inland rivers in the Hexi arid region. The mountain glaciers are an important water resources for this region. Changes of the mountain runoffs resulted from global climate warming will have important impacts on the development of human society and economy in the region. In this paper, the river runoffs from the Qilian Mountains and their dynamic changes are analyzed on the basis of the instrumental data of precipitation, air temperature, and discharge from the weather and hydrological stations in the study area. The results show that the annual change in the mountain runoffs is affected mainly by precipitation in the east of the region, but also by temeprature in the west of the region. There are some obvious regional differences in the influence of climatic change on surface runoffs in the Hexi region. River runoffs in the western part of the Hexi region have been increasing, whereas those in the eastern part have been decreasing. River runoffs in the central part such as the Heihe River, present a slow increasing trend, although it is not quite visible  相似文献   

5.
Granite with extremely low permeability has been selected to host a repository of spent nuclear fuel in the Czech Republic. Three boreholes were drilled in a test site of the Podlesi granite stock in the Krusne hory Mts. The holes were located 10 m apart. After hydraulic tests, four sections in one of the boreholes were separated by packers at depth of 69-111, 111-161, 161-220 and 220-300 m. Samples of groundwater from each section were periodically collected for chemical and isotopic analysis. Groundwater from fractures in the granite stock does not belong to a single and uniform groundwater body in spite of that the granite is chemically and mineralogically homogeneous. There are three water bodies, which are only partly hydraulically connected. They are： （1） The groundwater in the oxidation zone to a depth of about 111 m. （2） The groundwater of the zone of hydrolysis of alumosilicates from 111 to 220 m. （3） The groundwater of the zone of hydrolysis of alumosilicates below the depth of 220 m from a different fracture system than the water from the above sections. The total dissolved solids of water increase with depth. The Ca-SO4 component predominates in the near surface water body while Na-HCO3 component predominates in the two deeper water bodies. Water from the oxidation zone contains higher concentrations of iron and other trace metals. The chemical composition of water in the three water bodies changed during the 14 months of sampling. No steady state was reached during this time. The changes displayed systematic trends. The ratio Ca/Na increased and the ratio HCO3/SO4 decreased with time in the shallow water body. In contrast, the ratio CafNa decreased and HCO3/SO4 fluctuated without an obvious trend in the deeper water bodies. An unusually high concentration of dissolved organic carbon （DOC） was found in the lowest section of the test borehole. The concentration of DOC was 150 mg/L at the beginning of sampling. The isotopic composition was δ^13C=-27.6 ‰. The concentration of DOC dropped both towards the surface and with time.  相似文献   

6.
In the coastal aquifers of Kaluvelly （Bengal coast, India）, the over exploitation of the main aquifer （the Vanur sandstone） has created a piezometric depression. Water flows from the sea towards inland. A salinization problem is questioned. The geochemical study was dedicated to major, minor and trace elements as well as isotope ratios （δ^18O, δD, δ^37Cl and ^87Sr/^86Sr）. The catchment comprises a crystalline bedrock hinterland （chamockites） overlaid by sediment. The Vanur and Cuddalore sandstones, the two main layers, are issued from the decay of chamockites upland. The geochemical feature of a water body is linked both to the composition of the hosted rock and the interaction time between water and rock. In the deeper parts of the Vanur aquifer, a mixture with long-residence time groundwaters has been evidenced. These waters can originate from a pocket of water entrapped in the Vanur or from the charnockites downward. No seawater intrusion could be assessed. Piezometric data suggest a possible hydraulic connection between the Cuddalore and the Vanur aquifers. Major, minor element data and isotope ratios do not allow to distinguish between old waters from the different aquifers. Data evidence the heterogeneity of the charnokite formation which is characterized by high Ba contents. On the whole, the two sandstones are depleted compared to charnockites in alkaline and earth-alkaline elements, and enriched in less soluble element such as Th or Zr. Trace elements in groundwaters waters from the chamockite aquifer exhibit a high concentration of Ba as compared to Vanur and Cuddalore waters. As Ba is a soluble element, the concentration of Ba in waters is related to the concentration in the hosted rocks. The Li concentration, slightly higher in Vanur rocks, allows to distinguish waters from the deeper parts of the Vanur aquifer. For insoluble elements such as Ti, the hosted rock signature cannot be seen. The Ti concentration in water samples seems to rely on the reaction progress rather than on the available amount. Trace element data show that waters recovered from chamockites and sandstone aquifers present different geochemical features. The host rock signature can be seen in the chamockite and Vanur aquifers for some alkaline and alkaline-earth elements （mainly Ba and Li）.  相似文献   

7.
The aim of the present study is to locate and decipher the groundwater quality,types,and hydrogeochemical reactions,which are responsible for elevated concentration of fluoride in the Chhindwara district in Madhya Pradesh,India.Groundwater samples,quality data and other ancillary information were collected for 26 villages in the Chhindwara District,M.P.India during May 2006.The saturation index was computed for the selected samples in the region,which suggest that generally most of the minerals are saturated with respect to water.The concentration of fluoride in the region varies from 0.6 to 4.74 mg/l,which is much higher as per the national and international water quality standards.The study also reveals that the fluoride bearing rock formations are the main source of the higher concentration of fluoride in groundwater along with the conjuncture of land use change.Moreover,the area is a hard rock terrain and consists of fractured granites and amygdaloidal and highly jointed compact basalt acting as good aquifer,which is probably enriching the high content of fluoride in groundwater.High concentration of fluoride is found in deeper level of groundwater and it is possible due to rock-water interaction,which requires further detailed investigation.The highly alkaline conditions indicate fluorite dissolution,which works as a major process for higher concentration of fluoride in the study area.The results of this study will ultimately help in the identification of risk areas and taking measures to mitigate negative impacts related to fluoride pollution and toxicity.  相似文献   

8.
The water system in a rural area of Lanmuchang in Southwest Guizhou is facing a risk of thallium (Tl) contamination due to Tl mineralization around the area. The major trace elements and Tl in the water system are studied to understand the hydrogeochemical processes of Tl constrained by Tl mineralization. The results showed that the dispersion pattern of Tl follows a descending order in concentration from mine groundwater (deep groundwater) →stream water→shallow groundwater→background water, reflecting the impact of Tl mineralization on the hydrogeochemical composition. Tl concentrations in stream water in both regimes are remarkably higher (2-30 fold) downstream than up- and mid-streams, probably caused by the unidentified discharge of deep groundwater. Low Tl levels are detected in the current drinking water, however, the highly elevated Tl in stream water and ground water may pose a potential environmental risk through daily washing and agricultural irrigation. This study suggests that human activities, such as agricultural irrigation, could intensify the environmental risk of Tl.  相似文献   

9.
Nyemo-Nagqu, Tibet, is rich in high-temperature geothermal resources. The geothermal fields in Yangbajain and Yangyi as well as 11 unexplored geothermal fields along the geothermal belt from Nyemo to Nagqu were systematically investigated and the hydrochemistry data were collected from the whole field. Meanwhile, H-O-C-S isotope data were obtained for the new fields, and H-O isotope data for the Yangbajain and Yangyi fields. A comparison of the Nyemo-Nagqu geothermal fields with those in the Yangbajain area shows that the types of high-temperature geothermal water are dominated by Cl-Na and Cl·HCO_3-Na, while the types of medium-high-temperature geothermal water are dominated by HCO_3-Na. The concentrations of Li, F, SiO_2, and HBO_2 in the geothermal water are positively correlated with Cl content, indicating possible mixing with magma water. The reservoir temperatures range from 90 to 270°C by geothermometers. Slight drifting of ~(18)O was recorded at the Dongweng and Nyingzhong high-temperature geothermal fields, while more significant drifting was recorded at Gulu. The geothermal water is mainly replenished by atmospheric precipitation. The low tritium contents(1 TU) of the geothermal water from Nyingzhong, Gulu, and Luoma indicate that it is mainly replenished by sub-modern(prior to 1952) water, while the high tritium content(8.4 TU) in Yuela implies modern water replenishment. Other geothermal fields are replenished by a mix of sub-modern fresher water. The isotopic data in this study show that the carbon and sulfur in the geothermal water originates mainly from sediment leaching, with some of the carbon and sulfur having a deep origin.  相似文献   

10.
Nitrogen and phosphorus are the major nutrients to cause eutrophication to degrade water quality of the Miyun Reservoir,a very important drinking water source of Bijing,China,and they are mainly from non-point sources.The watershed in Miyun County was selected as the study region with a totoal area of 1400km^2.Four typical monitoring catchments and two experimental units were used to monitor the precipitation,runoff,sediment yield and pollutant loading related to various land uses in the meantime.The results show that the total nutrient loss amounts of TN and TP are 898.07t/a,and 40.70t/a,respectively,in which nutrients N and P carried by runoff are 91.3% and 77.3%,respectively.There is relatively heavier soil eroson in the northern mountain area whereas the main nutrient loss occurs near the northeast edge of the reservoir.Different land uses would influence the loss amounts of non-point source pollutants.The amount of nutrient loss from the agricultural land per unit is highest,that from forestry comes next that from grassland is lowest.However,due to the variability of land use areas,agricultural land contributes a lot to TP and forestry lands to TN.  相似文献   

11.
Concentrations and loads of nitrate and total phosphorus and the sources of these two nutrients were investigated at the Panjiakou and Daheiting Reservoir system in northern Hebei Province, the People＇s Republic of China. The Luanhe River is the primary source of water to these reservoirs. The response of the reservoir system from the phosphorus loading, with respect to chlorophyll-a production from algae, was fitted to a model of normalized phosphorus loading which regresses the average summer-time chlorophyll-a concentration to the average annual phosphorus concentration of the reservoir. The reservoirs have a primary use for drinking water and partially supplies the city of Tianjin with its annual supply, but secondary uses include flood control and aqua culture （fish cages）. Comparison of the normalized phosphorus loading and chlorophyll-a response of this system to other reservoirs throughout the world from similar studies indicates an elevated level of eutrophication, which will require an approximate 10-fold decrease in phosphorus load reduction to bring the system to a more acceptable level of algal productivity. Isotopes of nitrogen and oxygen in dissolved nitrate were measured from the headwater streams and at various locations along the major river system that provides the majority of water to this reservoir, and within the two reservoirs.  相似文献   

12.
Fluoride contamination in groundwater resources of Alleppey,southern India   总被引：1，自引：0，他引：1  
Alleppey is one of the thickly populated coastal towns of the Kerala state in southern India.Groundwater is the main source of drinking water for the 240,991 people living in this region.The groundwater is being extracted from a multi-layer aquifer system of unconsolidated to semi-consolidated sedimentary formations,which range in age from Recent to Tertiary.The public water distribution system uses dug and tube wells.Though there were reports on fluoride contamination,this study reports for the first time excess fluoride and excess salinity in the drinking water of the region.The quality parameters,like Electrical Conductivity(EC) ranges from 266 to 3900 μs/cm,the fluoride content ranges from 0.68 to2.88 mg/L,and the chloride ranges between the 5.7 to 1253 mg/L.The main water types are Na-HC03,NaCO_3 and Na-Cl.The aqueous concentrations of F~- and CO_3~(2-) show positive correlation whereas F~- and Ca~(2+) show negative correlation.The source of fluoride in the groundwater could be from dissolution of fluorapatite,which is a common mineral in the Tertiary sediments of the area.Long residence time,sediment-groundwater interaction and facies changes(Ca-HCO_3 to Na-HCO_3) during groundwater flow regime are the major factors responsible for the high fluoride content in the groundwater of the area.High strontium content and high EC in some of the wells indicate saline water intrusion that could be due to the excess pumping from the deeper aquifers of the area.The water quality index computation has revealed that 62%of groundwater belongs to poor quality and is not suitable for domestic purposes as per BIS and WHO standards.Since the groundwater is the only source of drinking water in the area,proper treatment strategies and regulating the groundwater extraction are required as the quality deterioration poses serious threat to human health.  相似文献   

13.
As one of the most important buildup of persistent organic pollutants （POPs）, organochlorine pesticides （OCPs） have received more and more attention. Samples including sediments, water and marine products were collected. In the lab, nineteen types of organochlorine pesticides were tested using GC-ECD following US-EPA 8080A method. In the top sediments, the concentration of HCHs was 0.1-3.08 ng/g and the concentration of DDTs was 3.53-75.83 ng/g. In the bottom sediments, the concentration of HCHs was 0.1-3.59 ng/g and the concentration of DDTs was 1.56-81.68 ng/g. The concentration ranges of HCHs and DDTs in sea water were 1.31-9.96 ng/L and 0.78-6.51 ng/L, respectively. And the concentration ranges of HCHs and DDTs in land surface water were 7.04-14.08 ng/L and 3.82-9.66 ng/L, respectively. The residual levels of HCHs and DDTs in marine product samples ranges from 0.1 to 0.6 ng/g and from 0.57 to 85.02 ng/g, respectively. In this thesis, discussions of DDTs and HCHs in sediment, water and marine product samples were made. The following are the main results and conclusions： A general decreasing trend was found from the inner to outer sectors of the Bay for both sediment and water samples. The distribution of OCPs depends greatly on the different properties pertaining to them. The topography, redox, hydrodynamic condition as well as other factors also play an important role in controlling the distribution and fate of OCPs.  相似文献   

14.
Sulfur is one of the havardous elements in coal The concentrations of sulfur are relatively high in coal.The major forms of sulfur in coal are pyritic,organic and sulfate.Pyritic and organic sulfur generally account for the bulk of sulfur in coal.Elemental sulfur also occurs in coal,but only in trace to minor amounts.When coals are burned,leached and washed,sulfur will be released in the form of sulfide and H2S,which then reach with O2,water and other substances to change into vitriol,and in some places it may form acid rain.And they will impact water environment,acidify the soil and do great harm to plants and human health.In this paper,on the basis of the data from the Yanzhou mining district,the distribution and concentrations of sulfur are analyzed and the existing forms of sulfur are studied.The variation of sulfur and its impact on the environments also are described when coal is used.  相似文献   

15.
Endemic fluorosis, caused by excess fluoride in water, is widespread in the arid and semiarid tracts of India. This disorder is of recent origin and developed due to certain faulty water management practices. After Eager reported ‘dental mottling＇ among emigrants from Pozzuli in Italy in 1901, several such reports came from all over the world. From 3 works published independently from Pennsylvania, Arizona and South Africa in 1931, it was known that this disorder is caused by drinking water containing over 1 mg/L fluoride during formation of permanent teeth among children.‘Skeletal fluorosis/Osteofluorosis＇, affecting bones and joints among adults was reported by Moeller and Gudjonsson in 1932 due to accumulation of fluoride in hard tissues by drinking water with over 7 mg/L fluoride for several years. In course of time fluorosis has been reported in over 22 countries from all over the world. Fluorosis spreads now among 67 million people in the entire arid and semiarid tracts of India. The work of National Institute of Nutrition of India at Hyderabad in 1977 revealed the spread of endemic ‘genu valgum＇ （knock-knee） crippling lower limbs right from childhood in association with fluorosis in most parts of India. Although preliminary work revealed that genu valgum is caused by drinking waters poor in calcium and rich in molybdenum, efforts these disorders by supplying low-fluoride water should be taken up to know its exact cause to the communities could not so eradicate The governmental efforts to eradicate the problem.  相似文献   

16.
The chemical and isotopic characteristics of the water and suspended particulate materials(SPM)in the Yellow River were investigated on the samples collected from 29 hydrological monitoring stations in the mainstem and several major tributaries during 2004 to 2007.TheδD andδ~(18)O values of the Yellow River water vary in large ranges from-32‰to-91‰and from-3.1‰to-12.5‰,respectively.The characters of H and O isotope variations indicate that the major sources of the Yellow River water are meteoric water and snow melting water,and water cycle in the Yellow River basin is affected strongly by evaporation process and human activity.The average SPM content(9.635g/L)of the Yellow River is the highest among the world large rivers.Compared with the Yangtze River,the Yellow River SPM has much lower clay content and significantly higher contents of clastic silicates and carbonates.In comparison to the upper crust rocks,the Yellow River SPM contains less SiO_2,CaO,K_2O and Na_2O,but more TFe_2O_3,Co,Ni,Cu,Zn,Pb and Cd.The abnormal high Cd contents found in some sample may be related to local industrial activity.The REE contents and distribution pattern of the Yellow River SPM are very close to the average value of the global shale.The averageδ~(30)Si_(SPM)in the Yellow River(-0.11‰)is slightly higher than the average value(-0.22‰)of the Yangtze River SPM.The major factors controlling theδ~(30)Si_(SPM)of the Yellow River are the soil supply,the isotopic composition of the soil and the climate conditions.The TDS in the Yellow River are the highest among those of world large rivers.Fair correlations are observed among Cl~-,Na~+,K~+,and Mg~(2+)contents of the Yellow River water,indicating the effect of evaporation.The Ca~(2+)and Sr~(2+)concentrations show good correlation to the SO_4~(2-)concentration rather than HCO_3~-concentration,reflecting its origin from evaporates.The NO_3~-contents are affected by farmland fertilization.The Cu,Zn and Cd contents in dissolved load of the Yellow River water are all higher than those of average world large rivers,reflecting the effect of human activity.The dissolved load in the Yellow River water generally shows a REE distribution pattern parallel to those for the Yangtze River and the Xijiang River.Theδ~(30)Si values of the dissolved silicon vary in a range from 0.4‰to 2.9‰,averaging1.34‰.The major processes controlling the D_(Si)andδ~(30)Si_(Diss)of the Yellow River water are the weathering process of silicate rocks,growth of phytolith in plants,evaporation,dissolution of phytolith in soil,growth of fresh water diatom,adsorption and desorption of aqueous monosilicic acid on iron oxide and human activities.The averageδ~(30)Si_(Diss)value of the Yellow River is significantly lower than that of the Nile River,Yangtze River and Siberia rivers,but higher than those of other rivers,reflecting their differences in chemical weathering and biological activity.Theδ~(34)S_(SO4)values of the Yellow River water range from-3.8‰to 14.1‰,averaging 7.97‰.There is some correlation between SO_4~(2-)content andδ~(34)S_(SO4).The factors controlling theδ~(34)S_(SO4)of the Yellow River water are the SO_4 in the meteoric water,the SO_4 from gypsum or anhydrite in evaporite rocks,oxidation and dissolution of sulfides in the mineral deposits,magmatic rocks and sedimentary rocks,the sulfate reduction and precipitation process and the sulfate from fertilizer.The~(87)Sr/~(86)Sr ratios of all samplesrange from 0.71041 to 0.71237,averaging 0.71128.The variations in the~(87)Sr/~(86)Sr ratio and Sr concentration of river water are primarily caused by mixing of waters of various origins with different~(87)Sr/~(86)Sr ratios and Sr contents resulting from water-rock interaction with different rock types.  相似文献   

17.
The impact of water quality changes of the Changjiang River on dissolved CO2 and silicate concentration and seasonal flux in the water column for the past decades were evaluated, based on monitoring data from hydrographic gauge. It was found that dissolve…  相似文献   

18.
Variability of aquatic chemistry in central Guizhou karst region, China   总被引：1，自引：1，他引：0  
It is necessary to understand the aquatic chemical characterstics of natural surface fresh water for water quality assessment.The chemical data from different kinds of water in the central Guizhou karst area showd that spring water from carbonate rock cracks(crack-water)is of neutrality or meta-alkalinity and [C] Ca II type.The amounts of all ions and the concentrations of HCO3^- and Ca^2 were higher in the autumn than in the spring,The crack-water was influenced by the infiltration of surface water in the process of erosion and /or trans-portation with decreasing HCO3 and increasing pH,SO4^2-,Cl^-,K^ and Na^ during running in a certain distance on the land surface .In particular,the chemical compositions of the waters at Tianxingqiao(upper-stream),Shuiliandong(mid-waterfall)and Luoshuitan(down-pool)near the Huangguoshu Waterfall were much different from those of the crack-water.The concentration of SO4^2-,Na^ ,Fe^3 and NO3^- varied closely with seasons.The CaCO3 deposited violently with CO2 release in the spring ,In Lake Hongfeng the HCO3^-/SO4^2- equivalent ratios were only 2.1-2.4 ,but Ca^2 /Mg^2 up to 2.4-4.2.The Cl^- concentration increased by a factor of 1 and Na^ by order of magnitude relative to the spring water.These indicated the increase in artificial pollutant discharge in the Lake Hongfeng watershed.In addition,Proewater in the soils covering carbonate rocks belongs to strongly mineralized water,The obvious differences in water quality were controlled by carbonate deposition,sulphate mineralization and nitrogen fixation as well as ammonification.It is indicated thaty the chemical compositions in the waters from the karst region were unstable and changeable.  相似文献   

19.
Dissolved organic matter （DOM）, a mixture of numerous organic compounds of 30 to 300000 D, exists in all natural water resources including rivers, lakes and oceans, and plays a very important role in global carbon cycle and ecology. The DOM molecules absorb UV light strongly in short wavelengths and prevent microorganisms from being damaged by solar UV irradiation. Meanwhile, the large DOM molecules are then photodegraded into inorganic carbon and smaller organic molecules which are easier for bacterioplankton to digest. The Arkansas River is one of the largest rivers in the US, and a major input of organic materials to the Mississippi River and Gulf of Mexico. However, the photochemical properties of the DOM in the river water have not been investigated. To study this photodegradation process of the Arkansas River, water samples from the river were collected, filtered, sealed into quartz flasks, and exposed to sunlight for up to 15 hours. Some samples were retrieved from the flasks at certain time intervals. The intensity of the sunlight was measured during the exposure process at 30 min to 1 hr intervals. UV-vis absorption, fluorescence emission, 3D fluorescence spectra and DOM concentrations were determined for all retrieved samples. It was found that the total DOM concentration decreased while the dissolved inorganic carbon （DIC） concentration increased in the samples. UV absorption and fluorescence intensity of DOM decreased exponentially. The disappearance rate of UV absorption varied with wavelength. The loss of integral fluorescence was about 2.6 times that of the UV absorption at the excitation wavelength. In addition, the quantum yields also decreased, and the peak position of 3D fluorescence scan shifted to shorter wavelength.  相似文献   

20.
The Lower Triassic Jialingjiang Formation reservoirs are distributed widely in the East Sichuan Basin, which are composed mainly of fractured reservoirs. However, natural gas with high concentration of H2S, ranging from 4% to 7%, was discovered in the Wolonghe Gas pool consisting primarily of porous reservoirs, while the other over 20 fractured gas reservoirs have comparatively low, tiny and even no H2S within natural gases. Researches have proved the H2S of the above reservoirs are all from the TSR origin. Most of the Jialingjiang Formation natural gases are mainly generated from Lower Permian carbonate rocks, the Wolonghe gas pool＇s natural gases are from the Upper Permian Longtan Formation, and the natural gases of the Huangcaoxia and Fuchengzhai gas pools are all from Lower Silurian mudstone. The formation of H2S is controlled by the characteristics and temperature of reservoirs, and is not necessarily related with gas sources. The Jialingjiang Formation in East Sichuan is buried deeply and its reservoir temperature has ever attained the condition of the TSR reaction. Due to poor reservoir potential, most of the gas pools do not have enough room for hydrocarbon reaction except for the Wolonghe gas pool, and thus natural gases with high H2S concentration are difficult to be generated abundantly. The south part of East Sichuan did not generate natural gases with high H2S concentration because the reservoir was buried relatively shallow, and did not suffer high temperature. Hence, while predicting the distribution of H2S, the characteristics and temperature of reservoirs are the necessary factors to be considerd besides the existence of anhydrite.  相似文献   

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