Magnesium Ammonium Phosphate Production from Wastewater through Box–Behnken Design and Its Effect on Nutrient Element Uptake in Plants     

Ayla Uysal  Begüm Kuru 《洁净——土壤、空气、水》2013,41(5):447-454

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   

Characterization and Application of Dried Plants to Remove Heavy Metals,Nitrate, and Phosphate Ions from Industrial Wastewaters     

Mohamed Chiban  Amina Soudani  Fouad Sinan  Saida Tahrouch  Michel Persin 《洁净——土壤、空气、水》2011,39(4):376-383

Low cost adsorbents were prepared from dried plants for the removal of heavy metals, nitrate, and phosphate ions from industrial wastewaters. The efficiency of these adsorbents was investigated using batch adsorption technique at room temperature. The dried plant particles were characterized by N₂ at 77 K adsorption, scanning electron microscopy, energy dispersive X‐ray spectroscopy, Fourier transform infrared spectroscopy, and phytochemical screening. The adsorption experiments showed that the microparticles of the dried plants presented a good adsorption of heavy metals, phosphate, and nitrate ions from real wastewaters. This adsorption increased with increasing contact time. The equilibrium time was found to be 30 min for heavy metals and nitrate ions and 240 min for phosphate ions. After the adsorption process, the Pb(II) concentrations, as well as those of Cd(II), Cu(II), and Zn(II) were below the European drinking water norms concentrations. The percentage removal of heavy metals, nitrates, and phosphates from industrial wastewaters by dried plants was ～94% for Cd²⁺, ～92% for Cu²⁺, ～99% for Pb²⁺, ～97% for Zn²⁺, ～100% for ${\rm NO}_{{\rm 3}}^{{-} } $ and ～77% for ${\rm PO}_{{\rm 4}}^{3{-} } $ ions. It is proved that dried plants can be one alternative source for low cost absorbents to remove heavy metals, nitrate, and phosphate ions from municipal and industrial wastewaters.  相似文献   

Dynamics of Stream Water Quality during Snowmelt and Rainfall – Runoff Events in a Small Agricultural Catchment     

Petr Fučík  Markéta Kaplická  Tomáš Kvítek  Jana Peterková 《洁净——土壤、空气、水》2012,40(2):154-163

Surface water quality can vary a lot with fluctuating discharge during a Rainfall – runoff event. This paper uses a set of hydrological and hydrochemical variables to explain concentration–discharge loops and hysteresis of ${\rm NO}_{3}^{- } $ , ${\rm NH}_{4}^{ + } $ and total suspended solids in a brook dewatering a small upland agricultural catchment in the Czech Republic. Our study is based on data collected by a continuous monitoring approach provided by an automatic ISCO sampler both from snow thawing and rainfall – runoff events. Methods of correlation, regression and principal component analysis (PCA) were employed to reveal possible relationships among the variables. For ${\rm NO}_{3}^{- } $ and ${\rm NH}_{4}^{ + } $ , we found several types of concentration–discharge loops due to the loop rotation direction and also the loop curvature shape, in mutual combinations, no matter which type of a hydrological event it was related to. PCA indicated that ${\rm NO}_{3}^{- } $ loops correlated mostly with the length of a rising hydrograph limb and with the slope of the initial phase of a falling hydrograph limb, 5‐day amount of precipitation and runoff coefficient. In case of ${\rm NH}_{4}^{ + } $ , the concentrations usually increased with elevated discharge, whereas PCA did not detect any closer linkages. For suspended solids, an unambiguous positive monotonic relationship was discovered. Although no definite pattern was found, this study showed the necessity of a continuous water quality monitoring system as an approach for capturing and understanding relationships between solute concentrations and runoff formation for tracing and modelling catchment pollution sources and describing transport processes.  相似文献   

Factors controlling nitrogen release from two forested catchments with contrasting hydrochemical responses     

Sheila F. Christopher  Myron J. Mitchell  Michael R. McHale  Elizabeth W. Boyer  Douglas A. Burns  Carol Kendall 《水文研究》2008,22(1):46-62

Quantifying biogeochemical cycles of nitrogen (N) and the associated fluxes to surface waters remains challenging, given the need to deal with spatial and temporal variability and to characterize complex and heterogeneous landscapes. We focused our study on catchments S14 and S15 located in the Adirondack Mountains of New York, USA, which have similar topographic and hydrologic characteristics but contrasting stream nitrate ( ) concentrations. We characterized the mechanisms by which reaches the streams during hydrological events in these catchments, aiming to reconcile our field data with our conceptual model of factors that regulate nutrient exports from forested catchments. Combined hydrometric, chemical and isotopic (δ ) data showed that the relative contributions of both soil and ground water sources were similar between the two catchments. Temporal patterns of stream chemistry were markedly different between S14 and S15, however, because the water sources in the two catchments have different solute concentrations. During late summer/fall, the largest source of in S14 was till groundwater, whereas shallow soil was the largest source in S15. concentrations in surface water decreased in S14, whereas they increased in S15 because an increasing proportion of stream flow was derived from shallow soil sources. During snowmelt, the largest sources of were in the near‐surface soil in both catchments. Concentrations of increased as stream discharge increased and usually peaked before peak discharge, when shallow soil water sources made the largest contribution to stream discharge. The timing of peaks in stream concentrations was affected by antecedent moisture conditions. By elucidating the factors that affect sources and transport of N, including differences in the soil nutrient cycling and hydrological characteristics of S14 and S15, this study contributes to the overall conceptualization of release from temperate forested catchments. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Monitoring of Microbiological Attributes of Soil and Groundwater Exposed to Metal Industrial Effluents     

Monica Rawat  Jaiprakash N. Rai 《洁净——土壤、空气、水》2013,41(11):1108-1115

The present paper evaluates the temporal and spatial impact of heavy metal containing (Cr, Zn, Cu, Ni, Cd and Fe) effluents of brass, electroplating and tannery industries on chemical and microbiological characteristics of affected soil and groundwater. Therefore, samples were drawn from three sites, S₁, S₂ and S₃, with a longitudinally distant from effluent drain of 20, 200 and 700 m, respectively. In general, the metals concentration exceeded the standard limits not only in the discharged effluents but also in the soil and groundwater. The significant reduction of microbial biomass C and N, soil respiration and microbial coefficient with increasing metal content from S₃ to S₁ was recorded, the effect being more pronounced in summer. However, the C_mic/N_mic ratio decreased whilst the metabolic quotient ($q_{{\rm CO}_{{\rm 2}} } $ ) increased with increasing metal concentration in soil. The content of Zn (11.5 mg/L) and Bacillus sp. was at maximum in groundwater of brass and electroplating industry site, whereas that of tannery site contained maximum Cr (2.34 mg/L) and Enterobacter sp. The toxic metals adversely polluted the groundwater which made it to harbours Escherichia coli beyond the prescribed limit. To check the soil and groundwater pollution, eco‐friendly measures involving improved effluent treatment technology and site‐specific application of treated effluent are recommended.  相似文献   

Average sand particle trajectory examined by the Raindrop Detachment and Wind‐driven Transport (RD‐WDT) process     

G. Erpul  D. Gabriels  W. M. Cornelis  H. Samray  T. Guzelordu 《地球表面变化过程与地形》2009,34(9):1270-1278

Recent studies of soil loss by the integrated action of raindrop impact and wind transport have demonstrated the significance of this mechanism. This paper presents data obtained during wind‐tunnel experiments examining the ‘Raindrop Detachment and Wind‐driven Transport’ (RD‐WDT) process to investigate average sand particle trajectory and the spatial extent at which the process operates. In the experimental design, at the same time as the horizontal wind velocities of 6·4, 10, and 12 m s^–1 passed through the tunnel, rainfall was simulated falling on very well sorted dune sand. The aspect and slope of the sand bed was varied to reproduce both windward (Ww) and leeward (Lw) slopes of 4º and 9º with respect to the prevailing wind direction. The average sand particle trajectories by the RD‐WDT process ( ) were estimated by a mass‐distribution function, which was integrated over a 7‐m uniform slope segment. The results showed that depended statistically upon the wind shear velocity (u*), and the effect of the slope gradient (θ) was insignificant on . This was different from that of the windless rain process ( ), ‘Raindrop Detachment and Splash‐driven Transport’ (RD‐ST), the spatial range of which relies strongly on θ. Additionally, was approximately 2·27 ± 2·2 times greater than the average path of a typical saltating sand particle of the rainless wind ( ), ‘Wind Erosion Saltation Transport’ (WE‐ST). Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Predicting Diel,Diurnal and Nocturnal Dynamics of Dissolved Oxygen and Chlorophyll‐a Using Regression Models and Neural Networks     

Nusret Karakaya  Fatih Evrendilek  Kerem Gungor  Deniz Onal 《洁净——土壤、空气、水》2013,41(9):872-877

Human‐induced and natural interruptions with continuous streams of observational data necessitate the development of gap‐filling and prediction strategies towards better understanding, monitoring and management of aquatic systems. This study quantified the efficacy of multiple non‐linear regression (MNLR) versus artificial neural network (ANN) models as well as the temporal partitioning of diurnal versus nocturnal data for the predictions of chlorophyll‐a (chl‐a) and dissolved oxygen (DO) dynamics. The temporal partitioning increased the predictive performances of the best MNLR models of diurnal DO by 45% and nocturnal DO by 4%, relative to the best diel MNLR model of diel DO ($r_{{\rm adj}}^{2} = 68.8\%$ ). The ANN‐based predictions had a higher predictive power than the MNLR‐based predictions for both chl‐a and DO except for diurnal DO dynamics. The best ANNs based on independent validations were multilayer perceptron (MLP) for diel chl‐a, generalized feedforward (GFF) for diurnal and nocturnal chl‐a, MLP for diel DO, GFF for diurnal DO, and MLP for nocturnal DO.  相似文献   

Adsorption of Complex Pollutants from Aqueous Solutions by Nanocomposite Materials     

Yeoung‐Sheng Wang  Shu‐Huei Hsieh  Chang‐Hung Lee  Jao‐Jia Horng 《洁净——土壤、空气、水》2013,41(6):574-580

In view of water pollutants becoming more complex, both anionic and cationic pollutants need to be removed. The multi‐pollutants simultaneous removal is paid more and more attention. Hence, development composite materials for treatment complex wastewater are the aim of this study. In this research, iron–nickel nanoparticles deposited onto aluminum oxide (α‐Al₂O₃) and carbon nanotubes (CNTs) to form nanocomposite materials Fe–Ni/Al₂O₃ and Fe–Ni/CNTs, respectively, were used as adsorbents. The adsorption capacities of Fe–Ni/Al₂O₃ and Fe–Ni/CNTs for AO7, HSeO, and Pb²⁺ were observed to be 5.46, 8.28, 27.02, and 25.6 mg/g, 15.29 and 17.12 mg/g, separately. The composite materials with negative charges were superior in adsorption of anionic pollutants. Using orthogonal experimental design and analysis of variance to co‐treat dye AO7, HSeO and Pb²⁺ in aqueous solutions, seven testing factors were included: (1) adsorbent types, (2) amount of iron, (3) solution pHs, (4) AO7 concentrations, (5) Pb²⁺ concentrations, (6) HSeO concentrations and (7) reaction time. The experimental results showed that the removal of complex pollutants AO7, HSeO, and Pb²⁺ on Fe–Ni/CNTs could reach up to 90% in the optimal treatment conditions. When using Fe–Ni/CNTs as the adsorbent, the sorption isothermals were well fitted in the Freundlich isotherm, and R² could reach up to 0.98.  相似文献   

Gewinnung biokinetischer Daten von Abwässern mit dem Respirationsfermentor. Teil 2: Einfluß des Sauerstoffpartialdruckes auf die spezifische Wachstumsrate beim aeroben biologischen Abbau von Prozeßwasser der Braunkohlenvergasung im mesophilen und im thermophilen Temperaturbereich     

G. Martius  U. Behrens  B. Franz 《洁净——土壤、空气、水》1987,15(4):389-400

An improved laboratory respiration fermentor construction for batchwise operations by which permeations of gases through connecting rubber tubings could be avoided is described. From the registration of curves for oxygen consumption during batchwise treatment of waste water from coal gasification at 37°C a decrease of the COD reduction rate is observed when the dissolved oxygen concentration decreased to below 0,7 mg/l. At dissolved oxygen concentrations above 0,7 mg/l, biokinetic data were determined which on account of the improved respiratory fermenter construction diverge strongly from the values formerly given \documentclass{article}\pagestyle{empty}\begin{document}$({\rm \mu = 0,24 h}^{{\rm - 1}};Y_{\frac{x}{{{\rm O}_2 }}} = 0,57{\rm g\; OBTSZ/g O}_{\rm 2};Y_{\frac{x}{s}} = 0,32{\rm g\; OBTSZ/g\; COD}) $\end{document}. Investigations performed in the thermophilic range (55°C) led at dissolved oxygen concentration of 1,5 mg/l to significant slower COD-reduction rates whereas at dissolved oxygen concentration of 1,5 mg/l the efficiency of COD-reduction was significantly higher than in the mesophilic range. The results obtained at different dissolved oxygen concentrations and different treating temperatures are discussed.  相似文献   

Catalytic Reduction of Hexaminecobalt(III) by Pitch‐based Spherical Activated Carbon (PBSAC)     

Yu Chen  Yan‐peng Mao  Hai‐song Zhu  Jing‐yi Cheng  Xiang‐li Long  Wei‐kang Yuan 《洁净——土壤、空气、水》2010,38(7):601-607

The wet ammonia (NH₃) desulfurization process can be retrofitted to remove nitric oxide (NO) and sulfur dioxide (SO₂) simultaneously by adding soluble cobalt(II) salt into the aqueous ammonia solution. Activated carbon is used as a catalyst to regenerate hexaminecobalt(II), Co(NH₃), so that NO removal efficiency can be maintained at a high level for a long time. In this study, the catalytic performance of pitch‐based spherical activated carbon (PBSAC) in the simultaneous removal of NO and SO₂ with this wet ammonia scrubbing process has been studied systematically. Experiments have been performed in a batch stirred cell to test the catalytic characteristics of PBSAC in the catalytic reduction of hexaminecobalt(III), Co(NH₃). The experimental results show that PBSAC is a much better catalyst in the catalytic reduction of Co(NH₃) than palm shell activated carbon (PSAC). The Co(NH₃) reduction reaction rate increases with PBSAC when the PBSAC dose is below 7.5 g/L. The Co(NH₃) reduction rate increases with its initial concentration. Best Co(NH₃) conversion is gained at a pH range of 2.0–6.0. A high temperature is favorable to such reaction. The intrinsic activation energy of 51.00 kJ/mol for the Co(NH₃) reduction catalyzed by PBSAC has been obtained. The experiments manifest that the simultaneous elimination of NO and SO₂ by the hexaminecobalt solution coupled with catalytic regeneration of hexaminecobalt(II) can maintain a NO removal efficiency of 90% for a long time.  相似文献   

Regulating Environmental Factors of Nutrients Release from Wheat Straw Biochar for Sustainable Agriculture   总被引：1，自引：0，他引：1  

Linin Wei  Gang Xu  Hongbo Shao  Junna Sun  Scott X. Chang 《洁净——土壤、空气、水》2013,41(7):697-701

One mechanism by which biochar application enhances soil nutrient availability is through direct nutrients release from biochar. However, factors controlling the release processes are poorly understood. In this study, the effects of pH, biochar to water ratio, temperature, ionic strength, and equilibration time on the release of PO, NO, NH, K⁺, Na⁺, Ca²⁺, and Mg²⁺ from biochar were evaluated in simulated experiments. The release of PO, K⁺, Ca²⁺, and Mg²⁺ was significantly affected by extraction pH, suggesting that their release from biochar was pH dependent or an H⁺‐consuming process. Correlation analysis indicated that PO and Ca²⁺, PO and Mg²⁺, and Ca²⁺ and Mg²⁺ were co‐solubilized with increasing soil acidity. To a lesser extent, the recovery of the nutrients was also affected by the ratio of biochar to water: more nutrients were soluble with more water supply. In contrast, the release of Na was not affected by pH while the concentration increased with decreasing biochar to water ratio. Meanwhile, other factors (temperature, ionic strength, and equilibration time) had less effect on nutrient release from biochar. Under the influence of pH, the patterns of NO and PO release from biochar were different: extractable NO concentration was not affected by the pH but more PO was released in strongly acidic conditions. Our data suggested that P was mainly retained in inorganic forms while N was in organic forms in biochar. We conclude that environmental factors have marked influences on nutrients release from biochar.  相似文献   

Adsorption–Reduction Behavior of Co(NH3) on Activated Carbon     

Yan‐Peng Mao  Yu Chen  Jing‐Yi Cheng  Hai‐Song Zhu  Xiang‐Li Long  Wei‐Kang Yuan 《洁净——土壤、空气、水》2012,40(2):117-122

A novel method has been put forward to retrofit the wet ammonia desulfurization process to realize the combined removal of sulfur dioxide and nitric oxide by introducing soluble cobalt(II) salt into aqueous ammonia solution. The active constituent of scrubbing NO from the flue gases is the produced by ammonia coordinating with Co²⁺. The regeneration of can be realized under the catalysis of activated carbon so as to sustain a high NO removal efficiency for a long time. In this paper, the adsorption–reduction behavior of on activated carbon has been researched using scanning electron microscopy, X‐ray diffraction, and X‐ray photoelectron spectroscopy. A conclusion can be drawn from the results that cobalt ions in the aqueous solution are adsorbed by activated carbon and most of them are reduced to Co²⁺ ions, and some of the Co²⁺ ions are further reduced into metallic cobalt. The results also demonstrate that the functional groups on the surface of carbon take part in this redox reaction. The C? H groups on the carbon surface are oxidized into C? OH, and then some of the hydroxyl groups are further oxidized into carbonyl or carboxyl groups.  相似文献   

Spatial and temporal variations in summer precipitation in Japanese mountain areas     

Yoshinori Shinohara  Tomonori Kume  Hikaru Komatsu  Kyoichi Otsuki 《水文研究》2010,24(13):1844-1855

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   

Mineral Content of Bottled and Desalinated Household Drinking Water in Kuwait     

Humood F. Al‐Mudhaf  Mohammad N. Al‐Hayan  Mustafa I. Selim  Abdel‐Sattar I. Abu‐Shady 《洁净——土壤、空气、水》2011,39(12):1068-1080

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   

The influence of fire and permafrost on sub‐arctic stream chemistry during storms     

K. C. Petrone  L. D. Hinzman  H. Shibata  J. B. Jones  R. D. Boone 《水文研究》2007,21(4):423-434

Permafrost and fire are important regulators of hydrochemistry and landscape structure in the discontinuous permafrost region of interior Alaska. We examined the influence of permafrost and a prescribed burn on concentrations of dissolved organic carbon (DOC), dissolved organic nitrogen (DON) and other solutes ( , Ca²⁺, K⁺, Mg²⁺, Na⁺) in streams of an experimentally burned watershed and two reference watersheds with varying extents of permafrost in the Caribou–Poker Creeks Research Watershed in interior Alaska. The low‐permafrost watershed has limited permafrost (3%), the high‐permafrost watershed has extensive permafrost (53%), and the burn watershed has intermediate permafrost coverage (18%). A three end‐member mixing model revealed fundamental hydrologic and chemical differences between watersheds due to the presence of permafrost. Stormflow in the low‐permafrost watershed was dominated by precipitation and overland flow, whereas the high‐permafrost watershed was dominated by flow through the active layer. In all watersheds, organic and groundwater flow paths controlled stream chemistry: DOC and DON increased with discharge (organic source) and base cations and (from weathering processes) decreased. Thawing of the active layer increased soil water storage in the high‐permafrost watershed from July to September, and attenuated the hydrologic response and solute flux to the stream. The FROSTFIRE prescribed burn, initiated on 8 July 1999, elevated nitrate concentrations for a short period after the first post‐fire storm on 25 July, but there was no increase after a second storm in September. During the July storm, nitrate export lagged behind the storm discharge peak, indicating a flushing of soluble nitrate that likely originated from burned soils. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Spatial Variation of the Precipitation Chemistry in the Thrace Region of Turkey     

Levent Şaylan  Barış Çaldağ  Fatih Bakanoğulları  Hüseyin Toros  Mustafa Yazgan  Orhan Şen  Yunus Özkoca 《洁净——土壤、空气、水》2011,39(5):491-501

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   

Evaluating equilibrium and non‐equilibrium transport of ammonium in a loam soil column          下载免费PDF全文

Lizhu Hou  Bill X. Hu  Zhiming Qi  Huan Yang 《水文研究》2018,32(1):80-92

Release of nitrogen compounds into groundwater, particularly those compounds from excessive agricultural fertilization, is a major concern in an aquifer recharge. Among the nitrogen compounds, ammonium ( ) is a common one. In order to assess the risk of agricultural fertilizer contamination to an aquifer through infiltration, adsorption onto a loamy agricultural soil profile (0–0.60 m depth) was studied using a soil column experiment and modelling simulation. The soil used in the experiment was drawn from an agricultural field in Xinzhen, Fangshan district, Beijing, China, and reconstituted in laboratory soil columns. Column experiments were conducted using bromide (conservative tracer) and ‐bearing aqueous solutions. The ammonium concentrations in the soil water samples were measured, and their values were plotted as the breakthrough curves. The chemical's soil–water distribution coefficients (K_d) were calculated using breakthrough curves. Then the retardation factor (R) in saturated soil was calculated. For the ‐bearing aqueous solutions, the strongest adsorption occurred at the soil depth of 0.30–0.45 m. The convection–dispersion equation model and chemical non‐equilibrium model in Hydrus‐1D were used to simulate transport in the loamy soil. The two‐site chemical non‐equilibrium model in Hydrus‐1D was best to simulate transport through the soil column. Parameter sensitivity study was conducted to investigate the influences of solute transport by K_d, the fraction of exchange sites assuming to be in equilibrium with the solution phase (f), the longitudinal dispersivity (λ), and the first‐order rate coefficients (ω). The sensitivity analysis results indicate K_d is the most critical parameter.  相似文献   

Temporal and spatial behaviour of rip channels in a multiple‐barred coastal system     

S. Quartel 《地球表面变化过程与地形》2009,34(2):163-176

A 15‐month data set of daily time‐averaged video images (Argus) has been analyzed to describe the spatial and temporal variability of the rip channels on a multiple‐barred coast at Noordwijk aan Zee, The Netherlands. The landward boundary of the intertidal bars and a proxy of the subtidal bar crest, defined as the intertidal and subtidal bar lines respectively, were derived from the Argus images. Local seaward‐directed deviations of the bar lines represent the cross‐shore and alongshore locations of the rip channels. The average intertidal rip spacing ( ) was 243 m, but the rips were not spaced regularly (σ_λ/ = 0.47). Some intertidal rips were observed to fill up during falling tide, but the majority remained open. The filled intertidal rip channels had more landward positions and migrated more slowly (2.4 versus 4.6 m/day) in the alongshore direction than the open intertidal rip channels. The number and the alongshore migration rate of open intertidal rip channels increased with the preceding wave heights (r = 0.26, p < 0.01) and alongshore component of the offshore wave power (r = 0.25, p < 0.01), respectively. The shape of the intertidal bar lines was similar to the subtidal bar line shape, suggesting that the intertidal morphology is coupled to the subtidal alongshore variability. The phase of two bar lines could vary from in phase (0°) to out of phase (180°). The phase changes gradually, due to different alongshore migration rates of the intertidal and subtidal bar lines. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Photocatalytic Degradation of 17α‐Ethinylestradiol and Inactivation of Escherichia coli Using Ag‐Modified TiO2 Nanotube Arrays     

Kai Mao  Yi Li  Houhu Zhang  Wenlong Zhang  Wenming Yan 《洁净——土壤、空气、水》2013,41(5):455-462

Ag‐modified TiO₂ nanotube arrays (Ag/TiO₂ NAs) were prepared and employed as a photocatalyst for degradation of 17α‐ethinylestradiol (EE2) and inactivation of Escherichia coli. The as‐synthesized Ag/TiO₂ NAs were characterized by field‐emission scanning electron microscope (FESEM), X‐ray diffraction (XRD), and X‐ray photoelectron spectroscopy (XPS). It was found that metallic Ag nanoparticles were firmly deposited on the TiO₂ NAs with the pore diameter of 100 nm and the length of 550 nm. Photocatalytic degradation of EE2 and inactivation of E. coli were enhanced effectively in an analogical trend using Ag/TiO₂ NAs. In particular, Ag/TiO₂ NAs exhibited the antimicrobial activity even in the absence of light. The Ag acted as a disinfection agent as well as the dopant of the modified TiO₂ NAs photocatalysis by forming a Schottky barrier on the surface of TiO₂ NAs. Inorganic ions suppressed the rates of photocatalytic degradation of EE2, with HCO having a more pronounced effect than NO or SO. Humic acid (HA) was found to increase the rate of EE2 degradation.  相似文献   

Capturing temporal variability for estimates of annual hydrochemical export from a first‐order agricultural catchment in southern Ontario,Canada     

M. L. Macrae  M. C. English  S. L. Schiff  M. Stone 《水文研究》2007,21(13):1651-1663

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