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1.
Concentrations of major ions in surface waters of the rivers of Khara-Murin and Snezhnaya are compared based on data of many-year observations carried out in the 1950s and 2000s. The concentrations of HCO 3 ? , Cl?, Ca2+, Mg2+, Na+ + K+ are shown to be stable. A considerable increase in SO 4 ?2 concentration was revealed.  相似文献   

2.
Dew samples were collected between October 2007 and February 2008 from a suburban site in Agra. pH, conductivity, major inorganic ions (F?, Cl?, NO 3 ? , SO 4 2? , Na+, K+, Ca2+, Mg2+, and NH 4 + ), and some trace metals (Cr, Sn, Zn, Pb, Cd, Ni, Mn, Fe, Si, Al, V, and Cu) were determined to study the chemistry of dew water. The mean pH was 7.3, and the samples exhibited high ionic concentrations. Dew chemistry suggested both natural and anthropogenic influences, with acidity being neutralized by atmospheric ammonia and soil constituents. Ion deposition flux varied from 0.25 to 3.0?neq?m?2?s?1, with maximum values for Ca2+ followed by NH 4 + , Mg2+, SO 4 2? , Cl?, NO 3 ? , Na+, K+, and F?. Concentrations of trace metals varied from 0.13 to 48?μg?l?1 with maximum concentrations of Si and minimum concentration of Cd. Correlation analysis suggested their contributions from both crustal and anthropogenic sources.  相似文献   

3.
The study aims to measure the hydrological behavior and nutrients dynamics of the springs located in different landscapes of Kosi basin, Indian central Himalaya. A total number of eight springs were considered for the present investigation, each landscape represented by one spring. The monitoring for hydrological measurement was conducted in January 1998 to December 1999, the interval between two successive measurements was 10 days, i.e., 240 hr (total 72 observations were made). Water quality measurement was done in three main seasons, i.e., winter (Jan.), summer (June) and monsoon (Aug.) of 1998 and 1999, and the average value for measured parameters were calculated. These samples were analyzed for pH, electrical conductivity, total dissolved solids, dissolve oxygen, Ca2?, Mg2?, Na?, Cl?, F?, NO 3 ? , and SO 4 2? . Hydrology of spring’s water showed that the reserve forest has a higher water retention capacity than the other landscapes, and the spring recharge capacity highly influenced by the settlements, open grazing, mismanaged agricultural and deforestation activities. The spring water chemistry shows that the springs located in forest and sparsely populated areas have lower EC, TDS, cationic and anionic concentration and are safe for drinking purposes, but those in irrigated land and densely populated areas feature higher EC, low dissolved oxygen concentration and higher NO 3 ? , which makes the water of these springs unsuitable for drinking. F concentration was higher in the springs located in the settlement area. In brief, the study indicates that the unmanaged drains, very poor and old pattern of sewage disposing system result in an increase in Na?, Cl?, F?, NO 3 ? , and SO 4 2? concentration as compared to the springs in agricultural and forested areas. All of the studied springs are badly managed which a is great threat for the longevity and quality of the water bodies, in particular, in Indian Central Himalayan region. This study suggests the ways of the constructional works, grazing. Forest resource extraction and agricultural activities in water bodies catchments area should also be controlled.  相似文献   

4.
On 11 March 2011, a moment magnitude M w = 9.0 earthquake occurred off the Japan Tohoku coast causing catastrophic damage and loss of human lives. In the immediate aftermath of the earthquake, we conducted the reconnaissance survey in the city of Rikuzentakata, Japan. In comparison with three previous historical tsunamis impacting the same region, the 2011 event presented the largest values with respect to the tsunami height, the inundation area and the inundation distance. A representative tsunami height of 15 m was recorded in Rikuzentakata, with increased heights of 20 m around rocky headlands. In terms of the inundation area, the 2011 Tohoku tsunami exceeded by almost 2.6 times the area flooded by the 1960 Chilean tsunami, which ranks second among the four events compared. The maximum tsunami inundation distance was 8.1 km along the Kesen River, exceeding the 1933 Showa and 1960 Chilean tsunami inundations by factors of 6.2 and 2.7, respectively. The overland tsunami inundation distance was less than 2 km. The tsunami inundation height linearly decreased along the Kesen River at a rate of approximately 1 m/km. Nevertheless, the measured inland tsunami heights exhibit significant variations on local and regional scales. A designated “tsunami control forest” planted with a cross-shore width of about 200 m along a 2 km stretch of Rikuzentakata coastline was completely overrun and failed to protect the local community during this extreme event. Similarly, many designated tsunami shelters were too low and were overwashed by tsunami waves, thereby failing to provide shelter for evacuees—a risk that had been underestimated.  相似文献   

5.
Three techniques for obtaining soil water solutions (gravitational and matrical waters extracted using both in situ tension lysimeters and in vitro pressure chambers) and their later chemical analysis were performed in order to know the evolution of the soil‐solution composition when water moves down through the soil, from the Ah soil horizon to the BwC‐ or C‐horizons of forest soils located in western Spain. Additionally, ion concentrations and water volumes of input waters to soil (canopy washout) and exported waters (drainage solutions from C‐horizons) were determined to establish the net balance of solutes in order to determine the rates of leaching or retention of ions. A generalized process of sorption or retention of most components (even Cl?) was observed, from the soil surface to the C‐horizon, in both gravitational and matrical waters, with H4SiO4, Mn2+, Na+, and SO42? being the net exported components from the soil through the groundwater. These results enhance the role of the recycling effect in these forest soils. The net percentages of elements retained in these forest soils, considering the inputs and the outputs balance, were 68% K+, 85% Ca2+, 58% Mg2+, 7% Al3+, 5% Fe3+, 34% Zn2+, 57% Cl?, and 20% NO3?, and about 75% of dissolved organic carbon was mineralized. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

6.
The 2010 Mentawai earthquake (magnitude 7.7) generated a destructive tsunami that caused more than 500 casualties in the Mentawai Islands, west of Sumatra, Indonesia. Seismological analyses indicate that this earthquake was an unusual “tsunami earthquake,” which produces much larger tsunamis than expected from the seismic magnitude. We carried out a field survey to measure tsunami heights and inundation distances, an inversion of tsunami waveforms to estimate the slip distribution on the fault, and inundation modeling to compare the measured and simulated tsunami heights. The measured tsunami heights at eight locations on the west coasts of North and South Pagai Island ranged from 2.5 to 9.3 m, but were mostly in the 4–7 m range. At three villages, the tsunami inundation extended more than 300 m. Interviews of local residents indicated that the earthquake ground shaking was less intense than during previous large earthquakes and did not cause any damage. Inversion of tsunami waveforms recorded at nine coastal tide gauges, a nearby GPS buoy, and a DART station indicated a large slip (maximum 6.1 m) on a shallower part of the fault near the trench axis, a distribution similar to other tsunami earthquakes. The total seismic moment estimated from tsunami waveform inversion was 1.0 × 1021 Nm, which corresponded to Mw 7.9. Computed coastal tsunami heights from this tsunami source model using linear equations are similar to the measured tsunami heights. The inundation heights computed by using detailed bathymetry and topography data and nonlinear equations including inundation were smaller than the measured ones. This may have been partly due to the limited resolution and accuracy of publically available bathymetry and topography data. One-dimensional run-up computations using our surveyed topography profiles showed that the computed heights were roughly similar to the measured ones.  相似文献   

7.
Groundwater quality in Ma’an area was evaluated for its suitability for drinking and agricultural uses by determining the main physical and chemical properties during a 1 year survey study (August 2009 to August 2010). Several samples were collected from ten different wells and analysed for temperature, pH, conductivity, total dissolved solids, total hardness, major cations (Ca2+, Mg2+, Na+ and K+), major anions (HCO3 ?, Cl?, NO3 ?, SO4 2?, F? and Br?) and trace metals (Fe2+, Al3+, Mn2+, Cu2+, Zn2+, Pb2+ and Cd2+). The general chemistry of water samples was typically of alkaline earth waters with prevailing bicarbonate chloride. The results showed great variations among the analyzed samples with respect to their physical and chemical parameters. However, most values were below the maximum permissible levels recommended by Jordanian and WHO drinking water standards. The quality assessment shows that in general, the GW in the study area is not entirely fit for direct drinking with respect to EC, and Pb2+. According to the residual sodium carbonate and sodium adsorption ratio, the water in the studied wells can be used for irrigational purposes.  相似文献   

8.
We examined the geochemical characteristics and temporal changes of deposits associated with the 2011 Tohoku‐oki tsunami. Stable carbon isotope ratios, biomarkers, and water‐leachable ions were measured in a sandy tsunami deposit and associated soils sampled at Hasunuma, Kujukuri coastal plain, Japan, in 2011 and 2014. At this site, the 2011 tsunami formed a 10–30 cm ‐thick layer of very fine to medium sand. The tsunami deposit was organic‐poor, and no samples contained any detectable biomarkers of either terrigenous or marine origin. In the underlying soil, we identified hydrocarbons and sterols derived from terrestrial plants, but detected no biomarkers of marine origin. In the samples collected in 2011, concentrations of tsunami‐derived water‐leachable ions were highest in the soil immediately beneath the tsunami deposit and then decreased gradually with depth. Because of its finer texture and higher organic content, the soil has a higher water‐holding capacity than the sandy tsunami deposit. This distribution suggests that ions derived from the tsunami quickly penetrated the sand layer and became concentrated in the underlying soil. In the samples collected in 2014, concentrations of water‐leachable ions were very low in both soil and sand. We attribute the decrease in ion concentrations to post‐tsunami rainfall, seepage, and seasonal changes in groundwater level. Although water‐leachable ions derived from seawater were concentrated in the soil beneath the tsunami deposit following the tsunami inundation, they were not retained for more than a few years. To elucidate the behavior of geochemical characteristics associated with tsunamis, further research on organic‐rich muddy deposits (muddy tsunami deposits and soils beneath sandy tsunami deposits) as well as sandy tsunami deposits is required.  相似文献   

9.
Xiaohu Wen  Meina Diao  De Wang  Meng Gao 《水文研究》2012,26(15):2322-2332
Groundwater salinization has become a crucial environmental problem worldwide and is considered the most widespread form of groundwater contamination in the coastal zone. In this study, a hydrochemical investigation was conducted in the eastern coastal shallow aquifer of Laizhou Bay to identify the hydrochemical characteristics and the salinity of groundwater using ionic ratios, deficit or excess of each ions, saturation indices and factor analysis. The results indicate that groundwater in the study area showed wide ranges and high standard deviations for most of hydrochemical parameters and can be classified into two hydrochemical facies, Ca2+‐Mg2+‐Cl‐ facies and Na+‐Cl‐ facies. The ionic ratio, deficit or excess of each ions and SI were applied to evaluate hydrochemical processes. The results obtained indicate that the salinization processes in the coastal zones were inverse cation exchange, dissolution of calcite and dolomite, and intensive agricultural practices. Factor analysis shows that three factors were determined (Factor 1: TDS, EC, Cl‐, Mg2+, Na+, K+, Ca2+ and SO42‐; Factor 2: HCO3‐ and pH; Factor 3: NO3‐ and pH), representing the signature of seawater intrusion in the coastal zone, weathering of water–soil/rock interaction, and nitrate contamination, respectively. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

10.
Sediment deposited by the Tohoku tsunami of March 11, 2011 in the Southern Kurils (Kunashir, Shikotan, Zeleniy, Yuri, Tanfiliev islands) was radically different from sedimentation during local strong storms and from tsunamis with larger runup at the same location. Sediments from the 2011 Tohoku tsunami were surveyed in the field, immediately and 6 months after the event, and analyzed in the laboratory for sediment granulometry, benthos Foraminifa assemblages, and diatom algae. Run-up elevation and inundation distance were calculated from the wrackline (accumulations of driftwood, woody debris, grass, and seaweed) marking the distal edge of tsunami inundation. Run-up of the tsunami was 5 m at maximum, and 3–4 m on average. Maximum distance of inundation was recorded in river mouths (up to 630 m), but was generally in the range of 50–80 m. Although similar to the local strong storms in runup height, the tsunami generally did not erode the coast, nor leave a deposit. However, deposits uncharacteristic of tsunami, described as brown aleuropelitic (silty and clayey) mud rich in organic matter, were found in closed bays facing the South Kuril Strait. These closed bays were covered with sea ice at the time of tsunami. As the tsunami waves broke the ice, the ice floes enhanced the bottom erosion on shoals and destruction of low-lying coastal peatland even at modest ranges of runup. In the muddy tsunami deposits, silt comprised up to 64 % and clay up to 41.5 %. The Foraminifera assemblages displayed features characteristic of benthic microfauna in the near-shore zone. Deep-sea diatoms recovered from tsunami deposits in two closely situated bays, namely Krabovaya and Otradnaya bays, had different requirements for environmental temperature, suggesting these different diatoms were brought to the bays by the tsunami wave entraining various water masses when skirting the island from the north and from the south.  相似文献   

11.
Centroid moment tensor solutions for the 2011 Tohoku earthquake are determined by W phase inversions using 5 and 10 min data recorded by the Full Range Seismograph Network of Japan (F-net). By a scaling relation of moment magnitude to rupture area and an assumption of rigidity of 4 × 1010 N m?2, simple rectangular earthquake fault models are estimated from the solutions. Tsunami inundations in the Sendai Plain, Minamisanriku, Rikuzentakata, and Taro are simulated using the estimated fault models. Then the simulated tsunami inundation area and heights are compared with the observations. Even the simulated tsunami heights and inundations from the W phase solution that used only 5 min data are considerably similar to the observations. The results are improved when using 10 min of W phase data. These show that the W phase solutions are reliable to be used for tsunami inundation modeling. Furthermore, the technique that combines W phase inversion and tsunami inundation modeling can produce results that have sufficient accuracy for tsunami early warning purposes.  相似文献   

12.
We present concentrations of environmentally available (unfiltered acidified 2% v/v HNO3) As, Cu, Cd, Pb, V, Sr, and major ions including Ca2+, Cl?, and SO42? in a July 2005 and a March 2006 shallow snow profile from the lower Eliot Glacier, Mount Hood, Oregon, and its proglacial stream, Eliot Creek. Low enrichment factors (EF) with respect to crustal averages suggests that in fresh March 2006 snow environmentally available elements are derived primarily from lithogenic sources. Soluble salts occurred in lower and less variable concentrations in July 2005 snow than March 2006. Conversely, environmentally available trace elements occurred in greater and more variable concentrations in July 2005 than March 2006 snow. Unlike major solutes, particulate‐associated trace elements are not readily eluted during the melt season. Additionally, elevated surface concentrations suggest that they are likely added throughout the year via dry deposition. In a 1‐h stream sampling, ratios of dissolved (<0·45 µm) V:Cl?, Sr:Cl?, and Cu:Cl? are enriched in the Eliot Stream with respect to their environmentally available trace element to Cl? ratios in Eliot Glacier snow, suggesting chemical weathering additions in the stream waters. Dissolved Pb:Cl? is depleted in the Eliot Stream with respect to the ratio of environmentally available Pb to Cl? in snow, corresponding to greater adsorption onto particles at greater pH values. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

13.
Changes in the chemical composition of the hot springs of Mendeleev Volcano (Kunashir Island) as for Cl?, SO 4 2? , CO2, NH 4 + and Cl?/SO 4 2? are given in function of the 1965–66 and 1973 (in part) seismic activity in the South Kurile islands.  相似文献   

14.
Stemflow of beech (Fagus sylvatica L.) represents a significant input of water and elements to the soil and might influence the spatial patterns and the rate of seepage fluxes at the stand scale. We investigated the soil solution chemistry at different depths and distances from the stem and the element fluxes with stemflow, throughfall and seepage in proximal and distal stem areas of a 130‐year‐old beech/oak forest in Steigerwald (northern Bavaria, Germany). The proximal stem area (in total 286 m2 ha−1) was defined as a 1 m2, 60 cm deep cylinder around the beech stem. Seepage fluxes were calculated by a soil hydrological model for 1996 using measured soil matrix potentials and tree xylem flow data for calibration. Stemflow represented 6·6% of the annual soil water input. With the exception of H+ fluxes, less than 10% of the total element fluxes with throughfall and stemflow reached the soil via stemflow. The volume‐weighted concentrations of H+, K+ and SO42− in stemflow were higher than those in throughfall, while other elements had similar concentrations. Soil solution K+ concentrations decreased with stem distance, but the Na+, Mg2+, Cl− and SO42− concentrations increased. Gradients for other elements were not statistically significant. Stemflow had a strong influence on the spatial patterns of element fluxes with seepage. The water fluxes through the soil of the proximal stem areas at a depth of 60 cm contributed 13·5% to the total seepage at the stand scale. Proximal to the stems about 20% of total seepage for K+, Mn2+, Aln+, dissolved organic N and dissolved organic C were concentrated, but only 8–10% for Na+, Mg2+ and Ca2+. The loss of acid‐neutralizing capacity calculated from the flux balance was about four times higher proximal to the stems compared with distal areas, indicating high rates of soil acidification proximal to the stems. Our results confirm the concept of a microsite around beech stems, characterized by high element and water fluxes in comparison with distal stem areas. Calculations of seepage fluxes and element budgets in beech stands have to consider the spatial heterogeneity of fluxes induced by stemflow. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

15.
Tsunamis are most destructive at near to regional distances, arriving within 20–30 min after a causative earthquake; effective early warning at these distances requires notification within 15 min or less. The size and impact of a tsunami also depend on sea floor displacement, which is related to the length, L, width, W, mean slip, D, and depth, z, of the earthquake rupture. Currently, the primary seismic discriminant for tsunami potential is the centroid-moment tensor magnitude, M w CMT , representing the product LWD and estimated via an indirect inversion procedure. However, the obtained M w CMT and the implied LWD value vary with rupture depth, earth model, and other factors, and are only available 20–30 min or more after an earthquake. The use of more direct discriminants for tsunami potential could avoid these problems and aid in effective early warning, especially for near to regional distances. Previously, we presented a direct procedure for rapid assessment of earthquake tsunami potential using two, simple measurements on P-wave seismograms—the predominant period on velocity records, T d , and the likelihood, T 50 Ex , that the high-frequency, apparent rupture-duration, T 0, exceeds 50–55 s. We have shown that T d and T 0 are related to the critical rupture parameters L, W, D, and z, and that either of the period–duration products T d T 0 or T d T 50 Ex gives more information on tsunami impact and size than M w CMT , M wp, and other currently used discriminants. These results imply that tsunami potential is not directly related to the product LWD from the “seismic” faulting model, as is assumed with the use of the M w CMT discriminant. Instead, information on rupture length, L, and depth, z, as provided by T d T 0 or T d T 50 Ex , can constrain well the tsunami potential of an earthquake. We introduce here special treatment of the signal around the S arrival at close stations, a modified, real-time, M wpd(RT) magnitude, and other procedures to enable early estimation of event parameters and tsunami discriminants. We show that with real-time data currently available in most regions of tsunami hazard, event locations, m b and M wp magnitudes, and the direct, period–duration discriminant, T d T 50 Ex can be determined within 5 min after an earthquake occurs, and T 0, T d T 0, and M wpd(RT) within approximately 10 min. This processing is implemented and running continuously in real-time within the Early-est earthquake monitor at INGV-Rome (http://early-est.rm.ingv.it). We also show that the difference m b  ? log10(T d T 0) forms a rapid discriminant for slow, tsunami earthquakes. The rapid availability of these measurements can aid in faster and more reliable tsunami early warning for near to regional distances.  相似文献   

16.
Regional source tsunamis pose a potentially devastating hazard to communities and infrastructure on the New Zealand coast. But major events are very uncommon. This dichotomy of infrequent but potentially devastating hazards makes realistic assessment of the risk challenging. Here, we describe a method to determine a probabilistic assessment of the tsunami hazard by regional source tsunamis with an “Average Recurrence Interval” of 2,500-years. The method is applied to the east Auckland region of New Zealand. From an assessment of potential regional tsunamigenic events over 100,000 years, the inundation of the Auckland region from the worst 100 events is modelled using a hydrodynamic model and probabilistic inundation depths on a 2,500-year time scale were determined. Tidal effects on the potential inundation were included by coupling the predicted wave heights with the probability density function of tidal heights at the inundation site. Results show that the more exposed northern section of the east coast and outer islands in the Hauraki Gulf face the greatest hazard from regional tsunamis in the Auckland region. Incorporating tidal effects into predictions of inundation reduced the predicted hazard compared to modelling all the tsunamis arriving at high tide giving a more accurate hazard assessment on the specified time scale. This study presents the first probabilistic analysis of dynamic modelling of tsunami inundation for the New Zealand coast and as such provides the most comprehensive assessment of tsunami inundation of the Auckland region from regional source tsunamis available to date.  相似文献   

17.
The hydrochemical analyses of twenty-three springs were used to determine the properties and types of groundwater of the Tertiary-Quaternary Aquifer of northern Jordan. The result shows that the geological formation influences the quality of the investigated groundwater more than the anthropogenic factors. The water of the Quaternary-Tertiary aquifer is enriched in Ca++ due to the dissolution of the nearby carbonate rocks. The investigated water has a low EC values with Ca(Na)-HCO3 water type. Most springs belong to this hydrochemical facies except Malka. Groundwater in the Malka wells has high salinity with NaCl waters and a strong Ca(Mg)-HCO3 facies (900 to 1000 mg/l TDS). The area long-term hydrochemical data have been also evaluated; general trend of increase of the analyzed ion was observed. Bicarbonate represents the most abundant anion in the studied water, which exceeds the permissible limits. Nitrates (NO 3 ? ) also exceed the permissible limit and are the most common contaminant in the investigated water. Data on dissolved major and trace elements (K+, Na+, Mg2+, Ca2+, Cl?, SO 4 2? , Fe, Zn, Cu and Pb) in the investigated water revealed that the concentrations lie within the natural background range. The positive correlation values between various ions indicate that most of ions come from same lithological sources. According to the residual sodium carbonate, and EC values, the studied springs are suitable for agricultural purposes.  相似文献   

18.
Acid‐neutralizing capacity (ANC) is an important index for streamwater acidification caused by external factors (i.e. chronic acid deposition) and internal factors such as soil acidification due to nitrification. In this study, the influence of forest clear‐cutting and subsequent regrowth on internal acidification was investigated in central Japan, where stream pH (near 7·0) and ANC (above 0·1 meq L?1) are high. pH, the concentrations of major cations (Na+, K+, Mg2+ and Ca2+), major anions (NO3?, Cl? and SO42?) and dissolved silica (Si), and ANC were measured in 33 watersheds of various stand ages, during 2002 to 2004. Only NO3? concentration decreased with stand age, whereas pH, ANC, and concentrations of the sum of base cations (BC) and Si were negatively correlated with the minimum elevation of the watershed. The correlation between the BC/Si ratio and minimum elevation suggested that factors contributing to acid neutralization changed at 1100 m above sea level. In watersheds at lower elevations (?1100 m), the relatively high contribution of soil water with longer soil contact times should result in higher ANC, and cation exchange reactions should be the dominant process for acid neutralization due to deposition of colluvial soils on the lower slope. In contrast, in higher‐elevation watersheds (≥1100 m), weathered residual soils are thin and the small contribution of deeper groundwater results in lower ANC. These results suggest that the local acid sensitivity is determined by the hydrological and geomorphologic factors generated by steep topography. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

19.
Observations of soil moisture and salt content were conducted from May to August at Neleger station in eastern Siberia. Seasonal changes of salt and soil moisture distribution in the active layer of larch forest (undisturbed) and a thermokarst depression known as an alas (disturbed) were studied. Electric conductivity ECe of the intact forest revealed higher concentrations that increased with depth from the soil surface into the active layer and the underlying permafrost: 1 mS cm?1 at 1·1 m, to 2·6 mS cm?1 at 160 cm depth in the permafrost. However, a maximum value of 5·4 mS cm?1 at 0·6 m depth was found in the dry area of the alas. The concentration of ions, especially Na+, Mg2+, Ca2+, SO42? and HCO3? in the upper layers of this long‐term disturbed site, indicates the upward movement of ions together with water. A higher concentration of solutes was found in profiles with deeper seasonal thawing. The accumulation of salts in the alas occurs from spring through into the growing season. The low concentration of salt in the surface soil layers appears to be linked to leaching of salts by rainfall. There are substantial differences between water content and electric conductivity of soil in the forest and alas. Modern salinization of the active layer in the alas is epigenetic, and it happens in summer as a result of spring water collection and high summer evaporation; the gradual salt accumulation in the alas in comparison with the forest is controlled by the annual balance of water and salts in the active layer. Present climatic trends point to continuous permafrost degradation in eastern Siberia increasing the risk of surface salinization, which has already contributed to changing the landscape by hindering the growth of forest. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

20.
The influence of geochemical processes and quality of groundwater in a rural tract of Damodar Valley region were investigated. The study has distinguished the groundwater as fresh, soft to moderately hard and mainly CaHCO3 type. The paired samples student’s t test shows the significant seasonal variations of pH, HCO3?, and Fe. Amphoteric exchange has lessened HCO3? concentration in post-monsoon which subsequently has caused to drop pH. Quite the reverse, the monsoon precipitation has triggered the additional release of Fe from iron-bearing sediments. The contaminant Cl? is from the domestic wastewater as is evidenced by field observations. The inter-variable relations, cation and anion mechanisms, and mineral saturation indices reveal that the dissolutions of silicate and carbonate minerals are the primary sources of major ions in groundwater. The chloro-alkaline indices showed the role of ion exchange too in water chemistry. The R-mode factor analysis also successfully identified two dominant processes regulating water chemistry—geogenic sources (Ca2+, Mg2+, Na+, and HCO3?) and anthropogenic inputs (mainly Cl?). The groundwater is found unsuitable for drinking at 82 and 93% of wells in pre- and post-monsoon seasons, respectively mainly due to elevated Fe content. The water from more than 90% of wells is appropriate for irrigation uses. The study recommends the proper treatment of contaminated water for consumption and measures to protect the groundwater from the waste water infiltration.  相似文献   

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