首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Pollutants affect not only the environment in which they originate since they are also transported by air currents to other locations. For this reason, air pollution is a global problem for all countries and the air and water quality need to be monitored carefully. More information on precipitation chemistry is required to determine the source of pollution as well as its effects on the ecosystems. In this study, precipitation chemistry has been analyzed for the first time by using simple bulk collectors located at four different sites in Northwest Turkey for a period of two years. About 650 sequential rainwater samples were collected and analyzed for pH, electrical conductivity, anions such as , , Cl?, and cations such as Na+, K+, Mg2+, Ca2+, and . The selected sites were under the effect of different environmental factors. Our results showed that the highest and concentrations were measured in the Northwest of the research area. Additionally, it has been found that Ca2+ ions are abundant within all rainwater samples.  相似文献   

2.
Three hundred and twenty‐two samples of desalinated household water were collected from 99 sampling locations that covered 95% of Kuwaiti's residential areas. Seventy‐one brands of bottled water were collected from Kuwaiti markets. The water quality parameters that were studied included pH, electrical conductivity (EC), total dissolved solids (TDS), F?, Cl?, Br?, , , , , , , , and the major macronutrients Na+, K+, Ca2+, and Mg2+. The analysis yielded a large range of results for most of these parameters, with differences in some cases exceeding 10‐fold. With a few exceptions, the results were found to comply with US‐EPA and WHO standards. Only the water in two brands of bottled water was acidic (pH < 6.5). The TDS was found to be higher than the US‐EPA regulated value in 4 and 3% of the household samples and bottled water brands, respectively. The fluoride levels were generally higher in bottled water than in household water. However, the household water that was produced by the Doha desalination plant and some of the European brands of bottled water were the best samples studied in terms of their quantity of Ca2+, Mg2+, and Na+ compared with the DRI values for those substances. EC and TDS were positively correlated with , , Na+, K+, Ca2+, and Mg2+ for household water but only with Ca2+ and Mg2+ for bottled water.  相似文献   

3.
We examined spatial and temporal variations in precipitation measured during summer season between 1976 and 2007 for 28 stations located in mountain areas across Japan using the amount of precipitation (Pr), the mean depth of precipitation events (η), and the inverse of the mean interval times (λ). We obtained positive correlations between the period mean Pr (Pr ) and the period mean η ( ) and between Pr and the period mean λ ( ) for the 28 stations. Pr was more strongly related to than to , indicating the spatial variations in Pr that are primarily related to the variations in . In addition, Pr was more strongly related to η than to λ for most stations on the basis of data for 1976–2007, indicating that the year‐to‐year variations in Pr are primarily related to η. We also examined temporal trends in Pr, η and λ for 1976–2007 and found no systematic trends for 23 of the 28 stations, suggesting long‐term trends that are not common in mountain areas of Japan. The relationships between Pr and and between Pr and η presented in this study enable us to generate a temporal precipitation distribution pattern based on only Pr and Pr data, respectively. Furthermore, probabilistic stochastic hydrological models require precipitation characteristics as input; thus, this study contributes to the determination of hydrological cycles and their possible future changes in Japanese mountain areas and therefore to water resource management. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

4.
This 2‐year study (2000, 2001) reports annual nutrient (phosphorus, nitrate) export from a first‐order agricultural watershed in southern Ontario based on an intensive monitoring programme. The importance of storm and melt events in annual export estimates is demonstrated and the temporal variability in nutrient loading during events is related to processes occurring within the catchment. The feasibility of predicting event‐related nutrient export from hydrometric data is explored. The importance of sampling frequency throughout events is also shown. Export of total phosphorus (TP), soluble reactive phosphorus (SRP) and nitrate ( ) for 2000 and 2001 averaged 0·35 kg ha?1 year?1, 0·09 kg ha?1 year?1, and 35 kg ha?1 year?1 (as N) respectively. Approximately 75% of annual TP export, 80% of annual SRP export and 70% of annual export occurred during 28 events per year. A small number of large‐magnitude events (>34 mm) accounted for 18–42% of annual TP export, 0–61% of annual SRP export and 13–33% of annual NO export. Our results show that temporal variability in nutrient export is largely governed by discharge in this basin, and export can be predicted from discharge. SRP and TP export can also be predicted from discharge, but only for events that are not large in magnitude. The sampling interval throughout events is important in obtaining precise estimates of nutrient export, as infrequent sampling intervals may over‐ or under‐estimate nutrient export by ± 45% per event for P. This study improves our understanding of and P export patterns and our ability to predict or model them by relating temporal variability in event nutrient export to discharge and processes occurring within the basin, and also by exploring the significance of sampling interval in the context of the importance of individual events, season and temporal variability during events. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

5.
Nano‐alumina modified by 9‐aminoacridine was used as a sorbent for separation and determination of dichromate ions from water. Statistical method, based on surface response design, has been used for the optimization of dichromate ions elution from 9‐aminoacridine nano‐alumina. The adsorbed dichromate ions were found to be eluted quantitatively with 0.8 mol L?1 KCl in 1.6 mol L?1 NaOH which optimized by response surface design. Under optimum conditions, the accuracy, precision (relative standard deviation, RSD%) and R‐square of the method were calculated as >98, <3, and >94%, respectively. Remarkable agreement between experimental and theoretical data was confirmed the predicted assumption. The method was applied to the simultaneous determination of dichromate in natural and industrial water samples. We also examined the retention of dichromate anions in the presence of Cl?, , and anions at pH 3.  相似文献   

6.
A study of the changes in the ionic loads of NO, NH, SO and H+ in a boreal forest snowpack at Lake Laflamme, Québec was carried out using hydrological and chemical data from field lysimeters. The results showed that depletion of the N-containing species occurs periodically in the snowpack during meltwater discharge. Rain-on-snow events led to in-pack losses of NO and NH at a rate of 130 μeq m?2 day?1 and 101·3 μeq m?2day?1 respectively. On dry days, however, dry deposition and deposition of organic debris from the canopy resulted in increases of 183·3 μeq m?2day?1 for NO and 4·5 μeq m?2day?1 for NH in the pack. In contrast, SO42? showed continual in-pack increases due to deposition of 5·0 μeq m?2day?1 for wet days and 92·6 μeq m?2day?1 for dry days. The depletion of NO and NH is due to microbiological uptake of these nutrients during periods when the free water content of the pack is high. Controlled melts in a laboratory snowmelt simulator containing snow and organic matter from the forest canopy at Lake Laflamme showed losses of NO and NH similar to those observed in the field. As the microbiological uptake proceeds at a rate comparable to that of ionic load increases in the pack by dry deposition, models of the chemical dynamics of snowmelt should take the former into account in any system where organic content of the snowpack is appreciable.  相似文献   

7.
J. Lewin  M. G. Macklin 《水文研究》2010,24(20):2900-2911
Floodplains may be transformed when environmental changes or human activity causes alluvial systems to cross channel pattern thresholds. Thresholds between pattern states based on occurrence fields are only available for some pattern distinctions, and these may not encompass the alluvial contexts and range of dynamic factors involved. Pattern changes now known from the UK Holocene are reviewed as a basis for appreciating the potential for future transformations in a changing environment. These involved episodic boulder and gravel spreads in upland environments, and braiding meandering, anastomosing → meandering and active inactive transformations in more lowland contexts. Concern for possible impacts of climatic change need to be grounded in an appreciation of the nature and scale of these past changes. Some potential future changes may be relatively predictable in location (braiding meandering); others are more difficult given both present knowledge and the varying, modified and inheritance‐rich ‘contexts of vulnerability’ that floodplains now represent. Implications for management are discussed. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

8.
Shallow and bedrock groundwater from granitic aquifers were investigated for the hydrogeochemistry of major and minor constituents in an agricultural area. Nitrate concentrations were observed up to 49 mg/l as NO3‐N, with 22% of samples exceeding the drinking water standard, which could pose a significant threat because most residents rely on groundwater as their drinking water source. Principal component analysis revealed three principal components (PCs): (1) nitrate contamination, contributed by major cations, Cl?, SO and NO , (2) reduction processes positively involving Fe, Mn and B, and negatively involving dissolved oxygen and NO and (3) natural mineralization, involving HCO and F?. Cluster analysis, performed on the PC scores, resulted in seven sample groups, which were successfully identified by total depth, elevation and land use. The nitrate‐contaminated groups had mixed land uses, with locally concentrated residential areas. Uncontaminated groundwater groups were found in the natural environment, including high‐altitude spring water and bedrock groundwater with a higher degree of natural mineralization. Shallow groundwater groups in paddy fields in lowlands were affected by reducing environments, of which one group was characterized by high Fe, Mn and B, and negligible nitrate. Groundwater with intermediate nitrate and lower Cl? and SO was found primarily in hilly terrains with orchards and vegetable gardens, indicating lower contaminant loadings than lowland areas. Higher concentrations of F? and nitrate were observed in the nitrate‐contaminated water, which seemed unlikely to be explained by groundwater mixing. The strong acidity generated from nitrification may infiltrate deeper into the aquifer, induce accelerated weathering of bedrock and result in the coexistence of F? and nitrate, which may be an evidence of intense nitrate loading, leading to soil acidification. Multivariate statistical analysis successfully delineated hydrochemical characteristics of groundwater attained by natural and anthropogenic processes in an agriculturally stressed area with complex topographic land use patterns. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

9.
Analysis of data characterizing the chemical composition of atmospheric precipitation was presented, with an emphasis on components responsible for neutralization of rain acidity. For this purpose, chemometric methods were applied. Based on a principal component analysis (PCA) a strong correlation between precipitation pH and potassium and ammonium ions in the heating period (October–March) and potassium and sodium ions in the non‐heating period (April–September) was observed. Additionally, a classification of eight variables, i.e., Na+, K+, Mg2+, Ca2+, , , Cl?, and according to their similarities was made using a cluster analysis. Based on this study, two ions, potassium and ammonium, together with the pH value were classified into one group (cluster) in the heating period while in the non‐heating period ions of potassium and sodium were clustered together with the pH. The results of the cluster analysis indicated that the selected ions contributed the most to the neutralization of the atmospheric precipitation acidity. This relationship was confirmed by a discriminant analysis in which potassium and ammonium ions were selected as components of the highest potential for precipitation classification according to its acidity degree. The relationship between the precipitation pH and the number of non‐precipitation days preceding the precipitation was also analyzed. It was found that although the observed an increase of the pH value was not very high, nevertheless, the effect of the duration of the period preceding the precipitation on the pH value recorded on the day of the precipitation occurrence was quite evident.  相似文献   

10.
In this study, bench‐scale experiments were conducted to examine the UV/H2O2 oxidation of 17α‐ethynyestradiol (EE2) in water in a batch operation mode. The EE2 degradation exhibited pseudo‐first‐order kinetics, and the removal was ascribed to the production of hydroxyl radicals (?OH) by the UV/H2O2 system. Typically, the EE2 oxidation rate increased with increasing UV intensity and H2O2 dose, and with deceasing initial EE2 levels and solution pH. At EE20 = 650 µg/L, UV intensity = 154 µW/cm2, H2O2 = 5 mg/L, and neutral pH, the UV/H2O2 treatment was able to remove 90% of the EE2 content within 30 min. Four anions commonly present in water were found to inhibit EE2 degradation to varying degrees: > > Cl? > . Our results demonstrate that the described UV/H2O2 process is an effective method to control EE2 pollution in water.  相似文献   

11.
A study was performed in two submerged, pilot‐scale biofilm bioreactors operated under different conditions to determine the relationship between the operating parameters and H2S emission. H2S was always detected in the exhaust air at concentrations varying from 1 to 353 ppmv. The specific aeration rate was the most influencing parameter, with As < 30 kg COD (dissolved oxygen concentrations <4 mg L?1) increasing noticeably the H2S production. The periodical removal of the accumulated sludge reduced H2S emissions by ~14%.  相似文献   

12.
Contamination of water due to bromate is a severe health hazard. The aim of the present study was to remove bromate from water using a crosslinked polystyrene based strongly basic anion exchange resin De‐Acidite FF‐IP. Batch experiments were performed to study the influence of various experimental parameters such as effect of pH, contact time, temperature, and effect of competing anions on bromate removal by De‐Acidite FF‐IP resin. At optimum parameters, the removal rate of bromate was very fast and 90% removal took place in 5 min and equilibrium was established within 10 min. The presence of competitive anions reduced the bromate adsorption in the order of Cl? > F? > CO > SO > NO > PO. The practical utility of this resin has been demonstrated by removing bromate in some of the commercial bottled water from Saudi Arabia. The level of bromate was determined using a very sensitive, precise and rapid method based on ultra‐performance liquid chromatography‐tendem mass spectrometry (UPLC‐MS/MS).  相似文献   

13.
The present study deals with the application of the hierarchical cluster analysis and non‐parametric tests in order to interpret the Gdańsk Beltway impact range. The data set represents concentration values for major inorganic ions (Na+, NH, K+, Mg2+, Ca2+, F, Cl, NO, and SO) as well as electrolytic conductivity and pH measured in various water samples [precipitation, throughfall water, road runoff, and surface water (drainage ditches, surface water reservoirs, and spring water)] collected in the vicinity of the beltway. Several similarity groups were discovered both in the objects and in the variables modes according to the water sample. In the majority of cases clear anthropogenic (fertilizers usage and transport, road salting in winter) and semi‐natural (sea salt aerosols, erosion of construction materials) impacts were discovered. Spatial variation was discovered for road runoff samples and samples collected from surface water reservoirs and springs. Surprisingly no clear seasonal variability was discovered for precipitation chemistry, while some evidences for existing of summer and winter specific chemical profile was discovered for road runoff samples. In general, limited range of the Gdańsk Beltway impact was proven.  相似文献   

14.
Errors in the kinematic wave and diffusion wave approximations for time-independent (or steady-state) cases of channel flow were derived for three types of boundary conditions: zero flow at the upstream end, and critical flow depth and zero depth gradient at the downstream end. The diffusion wave approximation was found to be in excellent agreement with the dynamic wave approximation, with errors in the range 1–2% for values of KF (? 7.5), where K is the kinematic wave number and F0 is the Froude number. Even for small values of KF (e.g. KF20 = 0.75), the errors were typically less than 15%. The accuracy of the diffusion wave approximation was greatly influenced by the downstream boundary condition. The error of the kinematic wave approximation was found to be less than 13% in the region 0.1 ? x ? 0.95 for KF = 7.5 and was greater than 30% for smaller values of KF (? 0.75). This error increased with strong downstream boundary control.  相似文献   

15.
The knowledge of total inorganic carbon concentration (c) is important for characterizing natural waters. It is usually measured by the titration alkalinity (“m-value”) and pH which depend on temperature and ionic strength. This paper demonstrates that Ca (and Mg) can influence the calculation of from titration alkalinity, too. Errors result from neglecting this influence. In such cases the share of ion pair CaCO amounts to more than 50 % of . General relationships among the influencing factors are given by tables calculated with the help of a BASIC computer programme for calculation from titration alkalinity, pH and Ca concentration.  相似文献   

16.
This study examined ${\rm NH}_{{\rm 4}}^{{\rm + }} $ , ${\rm PO}_{{\rm 4}}^{{\rm 3}- } $ recovery and the concentration of residual ions from anaerobic effluent of the potato processing industry through magnesium ammonium phosphate (MAP) precipitation using a Box–Behnken design. The regression model was statistically significant in terms of ${\rm NH}_{{\rm 4}}^{{\rm + }} $ and ${\rm PO}_{{\rm 4}}^{{\rm 3}- } $ removal efficiency and residual ion concentrations. Optimum ${\rm NH}_{{\rm 4}}^{{\rm + }} $ and ${\rm PO}_{{\rm 4}}^{{\rm 3}- } $ removal was obtained at pH 9.50 and at Mg2+/${\rm NH}_{{\rm 4}}^{{\rm + }} $ /${\rm PO}_{{\rm 4}}^{{\rm 3}- } $ molar ratio of 1.8:1:1.8. Under these conditions, Mg, Ca, K, Fe, and Cl concentrations required for plant growth significantly decreased with MAP precipitation, which was supported by EDX analysis of dry MAP precipitate. The fertilizer effect of MAP on the growth of corn and tomato plants was compared with chemical fertilizers through pot trials. Nutrient element uptake levels of plants were examined in different fertilizer sources. While Mg, Fe, Cu, Mn, and Zn nutrient element uptake levels were sufficient in MAP pots, Ca uptake exceeded sufficient level. Average levels of N, P, K, Mg, Cu, and Mn of corn plant were higher in MAP than other pots. The average N, P, and Mg levels of tomato plant in MAP pots were higher than other pots. N/K ratio, which is important in tomato plants, was better optimized in MAP pots. Only Ni, Cr, and Pb heavy metals were found in plants.  相似文献   

17.
Pharmaceutical compounds, widely produced and used all around the world, are partly responsible for the widespread water pollution in the environment. Carbamazepine (CBZ) is an antiepileptic drug that persists in the environment for many years. In the present study, we used the TiO2/UV, nanoparticulate zero‐valent iron (NZVI), and NZVI/H2O2 treatment processes to compare efficiency of CBZ removal from water. Influence of NZVI loading, H2O2 concentration, TiO2 loading, UV lamp power, and the matrix (distilled water and groundwater) on CBZ removal efficiency was evaluated using full factorial design. Results indicated that the NZVI/H2O2 process oxidized CBZ within 5 min. On the other hand, the NZVI process alone did not reduce CBZ concentration after 120 min of process time. The NZVI/H2O2 process was equally effective in CBZ removal from both distilled water and groundwater whereas the TiO2/UV process was less effective due to the presence of ions in groundwater. CBZ removal efficiency of the TiO2/UV process declined 30% when the matrix was changed from distilled water to groundwater. Negative divalent ions, i.e., and , were the main cause of reduction of CBZ removal efficiency from groundwater. It is likely that these two ions adsorb onto, and consequently prevent the superoxide anion and hydroxyl radical OH? from being generated on, the surface of the TiO2.  相似文献   

18.
Processes driving carbonate diagenesis in islands of the northern Bahamas are investigated using major ion, dissolved oxygen and dissolved organic carbon analyses of water samples from surface and ground waters, and measurements of soil gas P. Meteoric waters equilibrate with aragonite, but reactions are water controlled rather than mineral‐controlled and drive dissolution rather than concurrent precipitation of calcite. Surface runoff waters equilibrate with atmospheric P and rapidly recharge the vadose zone, limiting subaerial bedrock dissolution to only 6·6–15 mg l?1 Ca. P of soil gas measured in the summer wet season ((7·4 ± 3·7) × 10?3 atm) is elevated compared with that of the atmosphere, despite the thin skeletal organic nature of the soil and the discontinuous soil cover. Soil waters retained in surface pockets are equilibrated with respect to aragonite and have dissolved 51 ± 19 mg l?1 Ca. This is substantially less than the 93 ± 18 mg l?1 Ca in samples from pumping boreholes that sample meteoric waters from the freshwater lens. The high P of the freshwater lens ((16 ± 8·3) × 10?3 atm for pumping boreholes) suggests that significant additional CO2 may be derived by oxidation of soil‐ and surface‐derived organic carbon within the lens. The suboxic nature of the majority of the freshwater lens and the observed depletion in sulphate support this suggestion, and indicate that both aerobic and anaerobic oxidation may take place. Shallow lens samples from observation boreholes are calcite supersaturated and have a lower P than deeper lens waters, indicating that CO2 degasses from the water table, driving precipitation of calcite cements. We suggest that the geochemical evolution of waters in the vadose zone and upper part of the freshwater lens may be determined by the presence of a body of ground air with P controlled by production in the freshwater lens and soil and by degassing to the atmosphere. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

19.
HCHO is ubiquitous and important chemical constitutes in the troposphere. The concentrations of the HCHO (aq) in the rainwater were measured in the Guiyang city, southeastern of China from May 2006 to April 2007 and 153 discrete samples were collected. Rainwater (N = 151) HCHO (aq) concentrations ranged from lower than method detection limit (MDL) to 40.2 µmol/L with a volume weighted mean value of 7.4 ± 8.8 µmol/L. The strong correlations between HCHO (aq) and HCOO? (r = 0.69, n = 137), HCHO (aq) and nss‐ (r = 0.74, n = 137), HCHO (aq) and (r = 0.67, n = 137), HCHO (aq) and (r = 0.74, n = 133) suggest the significant influence of the anthropogenic input for the HCHO (aq) levels. The concentration levels of rainwater HCHO (aq) was inversely proportional to the amount of rainfall, indicating the below‐cloud process is the most important mechanism for rainwater HCHO (aq) scavenging processes. More than 70% of the HCHO (aq) wet deposition took place during the early stage of the rainfall. According to the air mass back‐trajectory analysis, the rainwater with industrial back‐trajectories coming from the north had the highest levels of HCHO (aq) while the rainwater with the green‐covered or marine back‐trajectories from the southeast had the lowest concentrations, and this indicate the HCHO (aq) originated from urban or industrial regions served as an important source of the rainwater. The annual HCHO (aq) wet deposition flux was calculated as 6.96 mmol/m2 per year and the total deposition flux was estimated as 24.35 mmol/m2 per year, 71.4% of which was dominated by dry deposition.  相似文献   

20.
It is shown that the new definition1 of strong motion local magnitude M leads to stable estimates of magnitudes for earthquakes in Yugoslavia, with epicentral distances R <100 km and for 2.5 < M < 6.5. Tables with magnitudes computed using this new procedure are presented for all earthquakes contributing to the strong motion accelerogram files in EQINFOS for Yugoslavia.2 The similarity of our findings with the analogous analyses for California suggests new possibilities for relative calibration between various local magnitude scales, which are used in southeastern Europe, and ML in California.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号