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1.
Gksu Delta is an important wetland where the Gksu River reaches to sea in the eastern of the town Tasucu-Ice1. The delta is classified as a Wetland of International Impor-tance according to the Ramsar Convention on Wetlands of International Importance. The amount of fertilizers used in this area was 7200 tons in 2006. These pollutants affect the surface and groundwater quality negatively. The intensively used fertilizers and pesticides contain not only N- and P compounds but also some heavy metals. The contents of all pol-lutants in surface waters were determined for four different seasons between 2006 and 2008 and with these data a Geographic Information System (GIS) has been constructed by using Map Info. From the photometric heavy metal analysis, it is inferred that the excess concen-tration of Fe, Ni, Mn, Mo and Cu at some locations is the cause of undesirable quality for drinking purposes. The source of excess concentration of various heavy metals is the agri-cultural activities and fertilizers. It is determined that in all periods between 2006 and 2008 the heavy metals and other pollutants in the fertilizers and pesticides transported easily to river water with irrigation return flow. The organic pollutants, including COD, BOD, NH3 and NO3 followed the sharply increasing trends from Silifke city to Mediterranean Sea. The water quality of Gksu River is modeled and determined that the waste water discharge of 10,700 m3/day from Silifke city does not create a serious problem because of the high amount of flow rate of Gksu River.  相似文献   

2.
澜沧江-湄公河重金属污染评价及大坝影响(英文)   总被引：1，自引：1，他引：0  
The resource development and changes of hydrological regime,sediment and water quality in the Mekong River basin have attracted great attentions.This research aimed to enhance the study on transboundary pollution of heavy metals in this international river.In this study,eight sampling sites were selected to collect the bed sand samples along the mainstream of the Mekong River.In addition,the contents of 5 heavy metal elements and their spatial variability along the mainstream of the river were analyzed.The geoaccumulation index(I geo) and potential ecological risk analysis were employed to assess heavy metal pollution status in the mainstream of the Mekong River.The results show that the average content of the heavy metal elements Zn is 91.43 mg/kg,Pb is 41.85 mg/kg,and As is 21.84 mg/kg in the bed sands of the Upper Mekong River,which are higher than those(Zn 68.17 mg/kg,Pb 28.22 mg/kg,As 14.97 mg/kg) in the Lower Mekong.The average content of Cr in the Lower Mekong is 418.86 mg/kg,higher than that in the Upper Mekong(42.19 mg/kg).Luang Prabang has a very high Cr concentration with 762.93 mg/kg and Pakse with 422.90 mg/kg.The concentration of Cu in all of the 8 sampling sites is similar,except for in Jiajiu with 11.70 mg/kg and Jiebei with 7.00 mg/kg.The results of the geoaccumulation index reveal that contaminations caused by Zn and Pb while Pb and As are more than those by Zn in Upper Mekong.Cr is the primary pollutant in the Lower Mekong,especially at Luang Prabang and Pakse.Slight pollution with As also occurs in Pakse.The potential ecological risk index indicates that the potential ecological risk of heavy metals in the mainstream of the Mekong River is low.We argue that the pollution of water quality and contamination of heavy metals in bed sediment caused by mining of mineral resources or geochemical background values in the Mekong is not transmitted from the Upper to the Lower Mekong because of the reservoir sedimentation and dilution along the river.  相似文献   

3.
With rapid economic and social development, soil contamination arising from heavy metals has become a serious problem in many parts of China. We collected a total of 445 samples(0–20 cm) at the nodes of a 2 km×2 km grid in surface soils of Rizhao city, and analyzed sources and risk pattern of 10 heavy metals(As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb and Zn). The combination of Multivariate statistics analysis and Geostatistical methods was applied to identify the sources and hazardous risk of heavy metals in soils. The result indicated that Cr, Ni, Co, Mn, Cu, and As were mainly controlled by parent materials and came from natural sources. Cd and Hg originated from anthropogenic sources. Pb and Zn, belonging to different groups in multivariate analysis, were associated with joint effect of parent materials and human inputs. Ordinary Kriging and Indicator Kriging suggested that single element and elements association from the same principal components had similar spatial distribution. Through comprehensive assessment on all elements, we also found the high risk areas were located in the populated urban areas and western study area, which could be attributed to the higher geological background in the western part and strong human interference in the eastern part.  相似文献   

4.
珠江广州河段微表层与次表层水环境质量比较(英文)   总被引：1，自引：0，他引：1  
The water quality in the surface microlayer(SML) and subsurface water(SSW) in the Guangzhou segment of Pearl River, a eutrophic urban river section in China, were analyzed. The spatial and temporal dynamics of nutrient concentrations, heavy metals and bacteria were examined from two sampling sites in monthly samples throughout 2010. The mean concentrations of total nitrogen, ammonia, nitrate and nitrite were higher than 7.0 mg/L, 3.1 mg/L, 1.1 mg/L and 0.3 mg/L, while total phosphorus and orthophosphate were 0.5 mg/L and 0.1 mg/L, respectively. These results indicated that the water quality was rich in minerals and eutrophic. The mean concentrations of Mn and Fe were higher than 0.013 mg/L; and Ni, Cr and Pb were higher than 0.001 mg/L. The mean concentrations were in the order of Mn Fe Ni Pb Cr. The concentrations of heavy metals in the Guangzhou segment were lower than the limit of the surface water quality standards in China and the World Health Organization(WHO), but higher than the median values in the world's freshwater. The density of bacteria ranged from 3.30×105 to 5.23×106 cells/mL, and the amount of cultivable heterotrophic bacteria ranged from 1.30×10 3 to 1.89×10 6 cfu/mL. Fecal coliform levels were beyond the V class of China water quality standard. The SML was enriched in nutrients, heavy metals and bacteria, with the maximum enrichment factor of 3.84 for nutrients, 8.00 for heavy metals, and 3.04 for bacteria, suggesting that the water quality of the SML of the Guangzhou segment of the Pearl River was more serious than in the SSW.  相似文献   

5.
The study was conducted to quantify the concentration and distribution of metals (Cd, Zn, Ni, Cu, Pb, and Fe) in the surface sediments and to assess the status of metal contaminations in the Klang River, Malaysia. The concentrations of metals (μg∕g, Fe%, dry weight) were as follows: 0.57-2.19 μg∕g Cd; 31.89-272.33 μg∕g Zn; 5.96-24.47 μg∕g Ni; 10.57-52.87 μg∕g Cu; 24.23-64.11 μg∕g Pb and 1.56%-3.03% Fe. Sequential extraction technique (SET) showed that mean anthropogenic portions of metals were in the order of Zn (60.22%), Cu (56.01%), Cd (45.63%), Ni (42.08%), Pb (33.22%) and Fe (10.26%). The highest concentrations of metals ( p<0.05) were found in the stations located close to industrial parks and highly populated areas. The results of the present study showed that the effectiveness of total organic carbon (TOC) contents in controlling the distribution and enrichment of metals was a more important factor compared to grain size. The study also indicated that the control of metals pollution from direct influx of domestic wastes and insufficiently treated industrial wastes in the Klang River was an important and desirable way to minimize the detrimental effects of metals.  相似文献   

6.
A total of 118 of agricultural soil and 43 of vegetable samples were collected from Dongguan City, Guangdong, China. The spatial distribution, sources, accumulation characteristics and potential risk of heavy metals in the agricultural soils and vegetables were depicted in details by three different approaches, including total contents of eight metal elements in soils and vegetables, GIS maps and multivariate analysis of heavy metals in soils in the study. The results show that there are higher accumulation of heavy metals such as Cu, Zn, Ni, Pb, Cd and Hg in agricultural soils, and the contents of Pb (65.38 mg kg?1) and Hg (0.24 mg kg?1) are 1.82 and 2.82 times of the background contents of the corresponding heavy metals in soils of Guangdong Province, respectively. There are about 3.4% of Cu, 5.9% of Ni, 1.7% of Cd and 28% of Hg in all collected soil samples from all investigated sites which have overran the contents for heavy metals of the China Environmental Quality Standard for Soils (GB15618-1995, Grade Ⅱ). The pollution characteristics of multi-metals in soils are mainly reflected by Hg. There are different sources to eight metal elements in soils, Cu, Zn, Ni, Cr and As are predominantly derived from parent materials, and Pb, Hg and Cd are affected by anthropogenic activities. The spatial distribution shows that the Cu, Zn, Ni, Cr, Pb, As and Hg contents of agricultural soils are high in the west and low in the east, and Cd contents are high in the northwest, southeast and low in the southwest in Dongguan. The ratios of vegetable samples which Ni, Pb and As concentrations higher than the Maximum Levels of Contaminants in Foods (GB2762-2005) are 4.7%, 16.3% and 48.8%, respectively. The order of bio-concentration factors (BCF) of heavy metals in vegetables is Cd > Zn > Cu > As > Ni > Hg > Cr > Pb. It is necessary to focus on potential risk of heavy metals for food safety and human’s health from agricultural soils and vegetables in Dongguan City, Guangdong Province.  相似文献   

7.
东莞市农田土壤和蔬菜重金属含量分析(英文)   总被引：7，自引：1，他引：6  
A total of 118 of agricultural soil and 43 of vegetable samples were collected from Dongguan City,Guangdong,China. The spatial distribution,sources,accumulation charac-teristics and potential risk of heavy metals in the agricultural soils and vegetables were de-picted in details by three different approaches,including total contents of eight metal ele-ments in soils and vegetables,GIS maps and multivariate analysis of heavy metals in soils in the study. The results show that there are higher accumulation of heavy metals such as Cu,Zn,Ni,Pb,Cd and Hg in agricultural soils,and the contents of Pb (65.38 mg kg-1) and Hg (0.24 mg kg-1) are 1.82 and 2.82 times of the background contents of the corresponding heavy metals in soils of Guangdong Province,respectively. There are about 3.4% of Cu,5.9% of Ni,1.7% of Cd and 28% of Hg in all collected soil samples from all investigated sites which have overran the contents for heavy metals of the China Environmental Quality Standard for Soils (GB15618-1995,Grade Ⅱ ). The pollution characteristics of multi-metals in soils are mainly reflected by Hg. There are different sources to eight metal elements in soils,Cu,Zn,Ni,Cr and As are predominantly derived from parent materials,and Pb,Hg and Cd are affected by anthropogenic activities. The spatial distribution shows that the Cu,Zn,Ni,Cr,Pb,As and Hg contents of agricultural soils are high in the west and low in the east,and Cd contents are high in the northwest,southeast and low in the southwest in Dongguan. The ratios of vegetable samples which Ni,Pb and As concentrations higher than the Maximum Levels of Con-taminants in Foods (GB2762-2005) are 4.7%,16.3% and 48.8%,respectively. The order of bio-concentration factors (BCF) of heavy metals in vegetables is Cd Zn Cu As Ni Hg Cr Pb. It is necessary to focus on potential risk of heavy metals for food safety and hu-man's health from agricultural soils and vegetables in Dongguan City,Guangdong Province.  相似文献   

8.
Heavy metal pollution is hazardous for the environment and human health. However,there are few studies of heavy metal pollution caused by historic metallurgical activity. The Laoniupo site in the Bahe River valley, Guanzhong Basin, China, was an important settlement of the Shang Culture(1600–1046 BCE). We studied two stratigraphic profiles at the Laoniupo site, which were used for measurements of magnetic susceptibility, heavy metal concentrations, and AMS ~(14) C ages to provide evidence of copper smelting activity at the site during the Shang Dynasty. The Nemerow Pollution Index and Geoaccumulation Index were calculated to assess the heavy metals record(Cu, Zn, Ni, Pb, Cr, and As) in the topsoil on the loess tableland. According to the Single Pollution Index, the topsoil was slightly polluted by As and unpolluted by Cu, Zn, Ni, Pb and Cr; according to the Nemerow Composite Pollution Index the topsoil was mildly polluted; and according to the Geoaccumulation Index, the topsoil was moderately polluted by As, slightly polluted by Cu, and unpolluted by Zn, Ni, Pb and Cr. The main cause of the heavy metal pollution in the topsoil is the presence of copper slag in the cultural layers that was disturbed by modern farming activity.  相似文献   

9.
湘江中下游农田土壤和蔬菜的重金属污染   总被引：11，自引：0，他引：11  
A total of 219 agricultural soil and 48 vegetable samples were collected from the midstream and downstream of the Xiangjiang River（the Hengyang-Changsha section）in Hunan Province.The accumulation characteristics,spatial distribution and potential risk of heavy metals in the agricultural soils and vegetables were depicted.There are higher accumulations of heavy metals such as As,Cd,Cu,Ni,Pb and Zn in agricultural soils,and the contents of Cd（2.44 mg kg^-1 ）,Pb（65.00 mg kg^-1 ）and Zn（144.13 mg kg^-1 ）are 7.97,3.69 and 1.63 times the corresponding background contents in soils of Hunan Province,respectively. 13.2%of As,68.5%of Cd,2.7%of Cu,2.7%of Ni,8.7%of Pb and 15.1%of Zn in soil samples from the investigated sites exceeded the maximum allowable heavy metal contents in the China Environmental Quality Standard for Soils（GB15618-1995,Grade Ⅱ）.The pollution characteristics of multi-metals in soils are mainly due to Cd.The contents of As,Cd,Cu,Pb and Zn in vegetable soils are significantly higher than the contents in paddy soils.95.8%, 68.8%,10.4%and 95.8%of vegetable samples exceeded the Maximum Levels of Contaminants in Foods（GB2762-2005）for As,Cd,Ni and Pb concentrations,respectively.There are significantly positive correlations between the concentrations of Cd,Pb and Zn in vegetables and the concentrations in the corresponding vegetable soils（p〈0.01）.It is very necessary to focus on the potential risk of heavy metals for food safety and human health in agricultural soils and vegetables in the midstream and downstream of the Xiangjiang River,Hunan Province of China.  相似文献   

10.
The concentrations of Cd, Cu, Pb, Zn, Ni and Fe were determined in the surface sediment and marine gastropod Nerita lineata collected in May 2005 from the intertidal zone of Dumai, Sumatera, Indonesia and Johor, Peninsular Malaysia. The results showed that metal concentrations in sediment and the soft tissue of N. lineata varied at different sampling stations. Mean heavy metal concentrations were 0. 92 μg/g(Cd) ;6.40 μg/g(Cu) ;32.77 μg/g(Pb) ;54.41μg/g(Zn) ;11.56 μg/g(Ni) and 2.97%(Fe) in sediment from Dumai and 1.15 μg(Cd) ;26.73 μg/g(Cu) ;53.45μg/g(Pb) ;130.77 μg/g(Zn) ;20.79 μg/g( Ni ) and 2.72% (Fe) in sediment from Johor. Concentrations of metals in gastropod N. lineata were 0.71 μg/g(Cd) ;15.16 μg(Cu) ;9.35 μg/g(Pb) ;94.69 μg/g(Zn) ;5.08 μg/g(Ni) and 397.97 μg/g(Fe) in samples from Dumai and 1.24 μg(Cd) ;18.02 μg/g(Cu) ;19.75 μg/g(Pb) ;95.09 μg/g(Zn) ;5.57 μg/g ( Ni ) and 473. 56 μg/g (Fe) in samples from Johor. Although they were not statistically significant (p >0.05), heavy metal concentrations in N. lineata were correlated with the concentrations of respective metals in sediment in both samples from Dumai and Johor. In general, samples of sediment and gastropod from Johor accumulated significantly higher heavy metal concentrations when compared to samples from Dumai(p < 0. 05). Higher concentrations of metals were recorded in samples collected from the stations close to the industrial and anthropogenic activities in both Dumai and Johor areas. However, most of the concentrations were still comparable to the previous reported studies from other geographical areas.  相似文献   

11.
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12.
Three kinds of tundra plant samples including Dicranum angustum(a type of boreal bryophyte),Puccinellia phryganodes(a type of fringy plant),Salix polaris(a type of vascular plant) and surface soil were samples in 200 at Ny-lesund of the Arctic.The levels of eight heavy metal elements(Hg,Pb,Cd,Cu,Zn,Ni,Fe and Mn) and three metal-like elements(As,Se,Sr) in the plant and soil samples of the areas within previous coal mining activities are significantly higher than those of other areas.The relative accumulation of these elements in these tundra plant samples is consistent with the one in the soil samples,especially in the areas affected by previous coal-mining activities.Thus,the pollution is apparently from local coal mining activity.Dicranum angustum has the highest concentrations among those elements,and it can be a good bio-indicator for heavy metal pollution in Ny-lesund.Though Ny-lesund is less polluted by heavy metal than nearby Northern European human living areas,but much more than the tundras of the Alaska,Greenland and the Antarctic.  相似文献   

13.
Three different aquatic ecosystems(an urban pond,Kelana Jaya Pond;a polluted river,Sepang River;and the intertidal and offshore areas of the west coast of Peninsular Malaysia)with different sets of ecological backgrounds and human activities were reviewed and assessed for the levels of Cu and Zn contamination with special reference to those found in polluted sediments collected from the Sepang River.The discussion on the contamination levels of Cu and Zn in the aquatic environment of Peninsular Malaysia was based on a comparison of the metal contamination of 4 kinds of aquatic environments.The comparison of 4 different areas was based on ① total concentrations of 2 metals;② the concentrations and percentages of the nonresistant(EFLE,acid-reducible and oxidisable-organic)and resistant geochemical fractions;and ③ correlation coefficients(R-values)based on data of 4 areas separately and a combination of 4 areas.The Sepang River recorded nonresistant fractions of 63.1% for Zn and 55.8% for Cu in addition to slightly lower metal concentrations when compared to those(60%-70%)reported before the shutting down of the piggery activities in that area.These nonresistant metal percentages(55%-63%)indicated that the metal concentrations were still dominated by anthropogenic sources since nonresistant fraction of metals were mostly contributed by anthropogenic sources.The positive results from the four different aquatic environments assessed here provided strong evidence to show that Malaysia's aquatic environment had received anthropogenic Cu and Zn.The present study also showed that the percentage of the nonresistant fraction and the R-values based on correlation analysis of Cu and Zn could be used as indicators of Cu and Zn pollution in the Malaysian aquatic ecosystem.Based on the present data,the correlation coefficients(R-values)are potential indicators of EFLE Cu and acid-reducible Cu of the sediments.The use of R-values as indicators of metal pollution is suggested and it is applicable to other heavy metal data although it should be improved in future studies.  相似文献   

14.
上海市崇明岛农田土壤重金属的环境质量评价(英文)   总被引：1，自引：0，他引：1  
The environmental quality of heavy metals (Pb,Cd,Cr,As,Hg) in agricultural surface soil of Chongming Island was assessed by national,local and professional standards based on a large scale investigation,in which 28 samples from vegetable plots,65 samples from paddy fields and 9 samples from watermelon fields were collected from whole island area. Results showed that the average concentration of Pb,Cd,Cr,As and Hg was 21.6 mg·kg-1,0.176 mg·kg-1,69.4 mg·kg-1,9.209 mg·kg-1 and 0.128 mg·kg-1,respectively. Compared with the background value of Shanghai City soil,except for Pb and Cr,all the other heavy metals average concentrations in Chongming Island agricultural surface soil exceeded their corresponding natural-background values. The concentrations of Cd,As and Hg were 33.0%,1.2% and 26.3% higher than the background value of Shanghai City,respectively. In addition,inverse distance interpolation (IDW) tool of GIS was also applied to study the spatial variation of heavy metals. The results indicated that most of agricultural soil quality was good,and the ratio of ecological,good soil,certified soil and disqualified soil were 1.26%,97.1%,1.47% and 0.12%,respectively. About 10.1%,85.7%,27.0%,55.4% and 55.2% soil samples exceeded the Pb,Cd,Cr,As and Hg background value of Shanghai City,respectively. Among these three land use type soils,vegetable soil was most seriously polluted by heavy metals,which is probably related to the over-application of pesticides. The annual deposition fluxes of Pb,Cd,As and Hg were 7736 μg.m-2.a-1,208 μg.m-2.a-1,2238 μg.m-2.a-1 and 52.8 μg.m-2.a-1,respectively. Crop straw burning was the important source of heavy metals of atmospheric deposition,and atmospheric deposition contributed a lot to heavy metals in agricultural soil in Chongming Island.  相似文献   

15.
地下水位变化对干旱区植被盖度的影响及其空间变异特征   总被引：5，自引：0，他引：5  
Sampling and testing are conducted on groundwater depth and vegetation coverage in the 670 km^2 of the Sangong River Basin and semi-variance function analysis is made afterwards on the data obtained by the application of geo-statistics. Results showed that the variance curve of the groundwater depth and vegetation coverage displays an exponential model. Analysis of sampling data in 2003 indicates that the groundwater depth and vegetation coverage change similarly in space in this area. The Sangong River Basin is composed of upper oasis, middle ecotone and lower sand dune. In oasis and ecotone, influenced by irrigation of the adjoining oasis, groundwater level has been raised and soil water content also increased compared with sand dune nearby, vegetation developed well. But in the lower reaches of the Sangong River Basin, because of descending of groundwater level, soil water content decreased and vegetation degenerated. From oasis to abandoned land and desert grassland, vegetation coverage and groundwater level changed greatly with significant difference respectively in spatial variation. Distinct but similar spatial variability exists among the groundwater depth and vegetation coverage in the study area, namely, the vegetation coverage decreasing (increasing) as the groundwater depth increases (decreases). This illustrates the great dependence of vegetation coverage on groundwater depth in arid regions and further implies that among the great number of factors affecting vegetation coverage in arid regions, groundwater depth turns out to be the most determinant one.  相似文献   

16.
塔里木河下游植被生态需水量(英文)   总被引：4，自引：0，他引：4  
We have appraised the relationships between soil moisture,groundwater depth, and plant species diversity in the lower reaches of the Tarim River in western China,by analyzing field data from 25 monitoring wells across eight study sites and 25 permanent vegetation survey plots.It is noted that groundwater depth,soil moisture and plant species diversity are closely related.It has been proven that the critical phreatic water depth is five meters in the lower reaches of the Tarim River.We acquired the mean phreatic evaporation of different groundwater levels every month by averaging the two results of phreatic evaporation using the Qunk and Averyanov formulas.Based on different vegetation types and acreage with different groundwater depth,the total ecological water demand(EWD)of natural vegetation in 2005 was 2.4×108m 3in the lower reaches of the Tarim River.Analyzing the monthly EWD,we found that the EWD in the growth season(from April to September)is 81%of the year's total EWD.The EWD in May,June and July was 47%of the year's total EWD,which indicates the best time for dispensing artificial water.This research aims at realizing the sustainable development of water resources and provides a scientific basis for water resource management and sound collocation of the Tarim River Basin.  相似文献   

17.
Understanding the variation in a plant's water sources is critical to understanding hydrological processes in water-limited environments. Here, we measured the stable-isotope ratios(δ18 O) of xylem water of Caragana microphylla, precipitation,soil water from different depths, and groundwater to quantitatively analyze the proportion of water sources for the shrub.We found that the water sources of C. microphylla differed with the plant's ages and the seasons. The main water source for young shrubs was upper-soil water, and it showed significant changes with seasonal precipitation inputs. In summer,the proportion contributed by shallow water was significantly increased with increased precipitation inputs. Then, the contribution from shallow-soil water decreased with the decline in precipitation input in spring and autumn. However, the adult shrubs resorted to deep-soil layers and groundwater as the main water sources during the whole growing season and showed much less seasonal variation. We conclude that the main water source of the young shrubs was upper-soil water and was controlled by precipitation inputs. However, once the shrub gradually grew up and the roots reached sufficient depth, the main water sources change from the upper-soil layer recharged by precipitation to deep-soil water and groundwater, which were relatively stable and abundant in the desert ecosystem. These results also suggest that desert shrubs may be able to switch their main water sources to deep and reliable water sources as their age increases, and this adjustment to water availability carries significant importance for their acclimation to the desert habitat.  相似文献   

18.
The distribution and concentrations of Cd, Cu, Pb and Zn were determined in the gills and remaining soft tissues of Perna viridis collected from 12 geographical sites （ 10 from the west and 2 from the east coastal waters） of Peninsular Malaysia. All samples showed that the levels of Cd, Pb and Zn were generally higher in the gill than those in the remaining soft tissues. These results could be due to the fact that gills are the first organ of metal accumulation and larger surface area with mucus sheets in the organ. Since the mussel gill is a better accumulator of Cd, Pb and Zn of ambient seawater than remaining soft tissue, it is a potential indicator of ambient levels of dissolved metals in the ambient seawater. However, further validations based on laboratory conditions are needed.  相似文献   

19.
Stable oxygen and hydrogen isotopic compositions （δ18O and δD） of soil water and shallow groundwater of a riparian forest, an artificial shrub forest, and Gobi of the lower reaches of the Heihe River Basin are used to study the recharge water sources of those ecosystems. IsoSource software is used to determine the δ180 values for root water of Populous euphratica and Tamarix ramosissima in the riparian forest ecosystem, Haloxylon ammodendron in the artificial shrub forest, and Reaumuria soongorica in the Gobi, as well as for local soil water and groundwater, and precipitation in the upper reaches of the Heihe River Basin. Our results showed that soil water and shallow groundwater of the riparian forest and the artificial shrub forest were recharged by river water which originated from precipitation in the upper reaches, and strong evaporation occurred in the artificial shrub forest. Soil water of the Gobi was not affected by Heihe River water due to this area being far away from the river channel. The main water sources of Populous euphratica were from 40-60-cm soil water and groundwater, and of Tamarix ramosissima were from 40-80-cm soil water in the riparian forest ecosystem. In the artificial forest, Haloxylon ammodendron used 200-cm saturated-layer soil water and shallow groundwater. The Reaumuria soongorica mainly used soil water from the 175-200-cm depth in the Gobi. Therefore, soil water and groundwater are the main water sources which maintain survival and growth of the plants in the extremely arid regions of the lower reaches of the Heihe River Basin.  相似文献   

20.
It is well known that the Hetao Basin is one of the most seriously arsenic-affected groundwater areas in China. In order to understand the characteristics of high arsenic(As) groundwater in the Basin, a brief overview of arsenic in groundwater follows. High arsenic in the Basin commonly occurs in shallow groundwater and the total arsenic concentrations range from 0.58 to 572 μg/L(average 99.73 μg/L), exceeding the maximum mandated value of 10 μg/L for drinking water in China; As(Ш) is the predominant species. The regional distribution pattern of arsenic in the groundwater increases from south/southeast to north/northwest. Hangjinhouqi and Wuyuan counties are considered as the most seriously affected areas, with high incidences of endemic arsenicosic diseases in the Hetao Basin. High groundwater arsenic correlates with the increase of well depth. Previous studies proposed that groundwater arsenic in the Basin is mainly originated from desorption of some natural solid materials in the sediments, under reducing condition. Generally, reducing condition is believed to be the primary factor for arsenic releasing from the sediment to groundwater in the region. Under inorganic or bacterial processes, Fe2O3 changes to Fe S and arsenic adsorbed to Fe(OH)3 dissolves into groundwater, and As(V) is reduced to As(Ш). Besides, reducing environments, groundwater hydraulic gradients, organic matter, p H, evapotranspiration, and soil texture are presumed to be the predominant factors that control arsenic mobilization.  相似文献   

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