Equilibrium,Thermodynamic, and Kinetic Studies on Lead (II) Biosorption from Aqueous Solution by Saccharomyces cerevisiae Biomass     

Mehrorang Ghaedi  Gholam Reza Ghezelbash  Farzaneh Marahel  Shiva Ehsanipour  Asma Najibi  Mustafa Soylak 《洁净——土壤、空气、水》2010,38(9):877-885

This paper presents a biosorption procedure for the preconcentration of Pb²⁺ ions using Saccharomyces cerevisiae biomass. The influence of several factors including pH, biomass dosage, contact time, and temperature on biosorption efficiency were optimized. At optimum value of all the equilibrium, thermodynamic, and kinetic parameters of Pb²⁺ ion biosorption was investigated by testing the Langmuir and Freundlich models and first and second order kinetic models were applied. The biosorption capacity of S. cerevisiae biomass was determined 89.6 mg/g, while the retained Pb²⁺ ions by S. cerevisiae were reversibly eluted using 5 mol/L HNO₃. Due to the high stability of S. cerevisiae the applied biomass can be used successively ten times with a slightly decrease (about 20%) in the recovery of Pb²⁺ ions. The calculated thermodynamic parameters, ΔG°, ΔH°, and ΔS° showed that the biosorption of Pb²⁺ ion onto S. cerevisiae biomass was feasible, spontaneous, and endothermic under examined conditions. The results of kinetic analysis showed that the biosorption processes of Pb²⁺ ions onto S. cerevisiae biomass followed pseudo second order kinetics.  相似文献   

Zytotoxikologische Untersuchung von Schadstoffen und Wasserblüten mit gefrierkonserviertem Bullensperma (Spermatest)     

L. Kalbe  R.-D. Recknagel 《洁净——土壤、空气、水》1985,13(2):185-194

The method is based on the determination of the number of the nonmotile sperms and/or the lethally damaged sperms with the aid of the fluorescent dye primuline. Incubation takes place at a suspension density of 10.000/mm³… 38.000/mm³, at 40°C or 46 °C for 15… 60 min. During the test with sublimate the loss of motility amounts to 55% at 4 mg/l Hg²⁺, the LC₅₀ is 7.3 mg/l Hg²⁺. Phenyl-mercuric acetate causes the total loss of motility with 20 mg/l, the LC₅₀ is above 168 mg/l (equivalent to 100 mg/l Hg²⁺). The LC₅₀ of sodiumpentadecylmonosulphonate and dodecylpyridinchloride are 11.6 and 15.8 mg/l, resp. Filtrates of blooming of cyanophyceae on Baltic, having been digested by repeated freezing and thawing, with 1.5… 6.4 g/l dry matter showed motility losses of 30… 100 % for Nodularia spumigena, whereas no significant effect was produced by a filtrate of Microcystis aeruginosa with 28.2 g/l dry matter as well as water-blooming of Nodularia spumigena from the Small Jasmund Bodden.  相似文献   

Adsorption studies of aqueous Pb(II) onto a sugarcane bagasse/multi-walled carbon nanotube composite     

《Physics and Chemistry of the Earth》2013

Adsorption of Pb²⁺ from aqueous solution onto a sugarcane bagasse/multi-walled carbon nanotube (MWCNT) composite was investigated by using a series of batch adsorption experiments and compared with the metal uptake ability of sugarcane bagasse. The efficiency of the adsorption processes was studied experimentally at various pH values, contact times, adsorbent masses, temperatures and initial Pb²⁺ concentrations. A pH of 4.5 was found to be the optimum pH to obtain a maximum adsorption percentage in 120 min of equilibration time. The composite showed a much enhanced adsorption capacity for Pb²⁺ of 56.6 mg g⁻¹ compared with 23.8 mg g⁻¹ for bagasse at 28 °C. The Langmuir adsorption isotherm provided the best fit to the equilibrium adsorption data. The pseudo first-order, pseudo second-order, intraparticle diffusion and Elovich kinetics models were used to analyse the rate of lead adsorption and the results show that the Elovich model is more suitable. The thermodynamic parameters of adsorption, namely ΔG°, ΔH° and ΔS°, were determined over the temperature range of 20–45 °C. The adsorption of Pb²⁺ onto both bagasse and the sugarcane bagasse/MWCNT composite was found to be spontaneous but for the former adsorbent it was enthalpy-driven whereas for the latter it was entropy-driven. Desorption of the lead-loaded adsorbents was fairly efficient with 0.1 mol dm⁻³ HCl. Overall this composite has the potential to be a good adsorbent for the removal of Pb²⁺ from wastewaters.  相似文献   

Treatability of Dye Solutions Containing Disperse Dyes by Fenton and Fenton‐Solar Light Oxidation Processes     

Fehiman Çiner  Ömür Gökkuş 《洁净——土壤、空气、水》2013,41(1):80-85

This study attempts to explore the possibility of treating dye solutions containing Disperse Yellow 119 and Disperse Red 167 by Fenton and Fenton under solar‐light oxidation processes. Experiments were conducted to examine the effects of various operating conditions on the performance of the treatment systems. The Fenton results showed that 98.6% spectral absorption coefficient (SAC) and 90.8% chemical oxygen demand (COD) removals were proved at pH 3, 50 mg/L Fe²⁺, and 75 mg/L H₂O₂, 15 min oxidation time for Disperse Yellow 119. After 40 min solar irradiation time during Fenton process the SAC removal was 99.1%. COD reduction of about 98.3% was observed at the same time. It was also obtained as 97.8% SAC and 97.7% COD removal with pH 3, 75 mg/L Fe²⁺, 100 mg/L H₂O₂, and 25 min oxidation time for Disperse Red 167 at this optimum conditions. For Disperse Red 167 during Fenton under solar light process, after 40 min of solar irradiation time the SAC and COD reduction were obtained 99.3 and 98.4%, respectively.  相似文献   

A Study: Removal of Cu(II), Cd(II), and Pb(II) Ions from Real Industrial Water and Contaminated Water Using Activated Sludge Biomass     

Erdal Kusvuran  Deniz Yildirim  Ali Samil  Osman Gulnaz 《洁净——土壤、空气、水》2012,40(11):1273-1283

This study aims to remove of Cu²⁺, Cd²⁺, and Pb²⁺ ions from solution and to investigate the adsorption isotherms, adsorption kinetics, and ion‐exchange affinities of these metals using waste activated sludge (AS) biomass. The adsorptions of the metals on biomass were optimal at an acidic pH value of 6.0 based on its monolayer capacities. Maximum monolayer capacities of AS biomass (q_max) were calculated as 0.478, 0.358, and 0.280 mmol g^?1 for Cu²⁺, Cd²⁺, and Pb²⁺, respectively, and the adsorption equilibrium time was found as 60 min for each metal. The adsorbed amount of metal rose with increasing of initial metal ion concentration. The equilibrium adsorption capacity of AS for initial 0.25 mmol L^?1 metal concentration was determined as 0.200, 0.167, and 0.155 mmol g^?1 for Cu²⁺, Cd²⁺, and Pb²⁺ ions, respectively. These relevant values were determined as 0.420, 0.305, and 0.282 mmol g^?1 for Cu²⁺, Cd²⁺, and Pb²⁺ ions, respectively, when initial metal concentration was 0.50 mmol L^?1. In the multi‐metal sorption system, the adsorption capacity of AS biomass was observed in the order of Cu²⁺ > Cd²⁺ > Pb²⁺. In the presence of 100 mmol L^?1 H⁺ ion, the order of ion‐exchange affinity with H⁺ was found as Cu²⁺ > Cd²⁺ > Pb²⁺. The adsorption kinetics were also found to be well described by the pseudo‐second‐order and intraparticle diffusion models. Two different rate constants were obtained as k_i1 and k_i2 and k_i1 (first stage) was found to be higher than k_i2 (second stage).  相似文献   

Toxicity of Interactions of Zinc —Nickel,Copper —Nickel and Zinc —Nickel —Copper to a Freshwater Teleost,Lebistes reticulatus (PETERS)1     

B. S. Khangarot 《洁净——土壤、空气、水》1981,9(5):495-503

The lethal toxicity of mixtures of Zn²⁺ —Ni²⁺, Cu²⁺ —Ni²⁺ and Zn²⁺ —Cu²⁺ —Ni²⁺ to common guppy at 21£C in hard water (total hardness = 260 mg/l as CaCO₃) was studied under static bioassays test conditions with renewal of the test solutions every 24 h. The heavy metals were tested separately and in mixtures. The 48 h median lethal concentrations (LC₅₀) for individual salts were 75 mg/l Zn²⁺, 37 mg/l for Ni²⁺ and 2.5 mg/l for Cu²⁺. Concentrations were expressed in “toxic units” by taking them as proportions of LC₅₀ values. Experiments showed that in the Zn²⁺-Ni²⁺ mixture, when Ni²⁺ was more in proportion, the toxicity was more than additive. The 48 h LC₅₀ value and 95% confidence limits in the Ni²⁺-Cu²⁺ mixture were 0.684 (0.484 … 0.807) toxic units and the mixture produced more than the additive toxicity (synergism.). The LC₅₀ value and its 95% confidence limits in a Zn²⁺?Cu²⁺?Ni²⁺ mixture also suggested that the mixture was again strictly additive. The results indicate that heavy metallic mixtures would pose a greater toxicological danger to fish than the respective individual metals.  相似文献   

Eliminierung von Schwermetallen aus komplexbildnerhaltigen Abwässern durch Kalk-/Kreide-Fällung     

H. Schilling  K. Fischwasser 《洁净——土壤、空气、水》1989,17(6):673-680

A report is given on laboratory investigations into model waters containing Cu²⁺-, Ni²⁺- or Zn²⁺-ions and tartrate, citrate, NTA or EDTA as complexing agents. There were determined residual concentrations of the metal ions at different shares of complexing agents, which are achieved by the precipitation with lime and chalk. Chalk is added in order to secure the required exess of calcium ions without causing an overalkalinization of the water. In the range of pH = 8…9, however, residual concentrations lower than 1 mg/1 are achieved only for copper ions in the presence of tartrate.  相似文献   

Degradation of Phenol in Aqueous Solution by Fenton,Sono‐Fenton and Sono‐photo‐Fenton Methods     

Arjunan Babuponnusami  Karuppan Muthukumar 《洁净——土壤、空气、水》2011,39(2):142-147

The present work focuses on the performance of Fenton, sono‐Fenton, and sono‐photo‐Fenton processes for the oxidation of phenol present in aqueous solution. The effects of H₂O₂ concentration, Fe²⁺ concentration, pH, and initial phenol concentration on the oxidation of phenol were studied. The optimum Fe²⁺ and H₂O₂ concentrations for the Fenton process were 45 and 800 mg/L, respectively. For the sono‐Fenton process, the optimum Fe²⁺ and H₂O₂ concentrations were 30 and 800 mg/L, respectively. The optimal conditions for the sono‐photo‐Fenton process were found to be 20 mg/L of Fe²⁺ and 700 mg/L of H₂O₂. The optimum pH was found to be 3 for the processes investigated in the present study. The analysis of results showed that the sono‐photo‐Fenton method reduced the Fe²⁺ concentration by 30–50% and the H₂O₂ concentration by 12.5%. It was found that the sono‐photo‐Fenton technique showed better performance than the Fenton and sono‐Fenton processes for the oxidation of phenol. A lumped kinetic model was used to predict the chemical oxygen demand reduction and the model was found to fit the data.  相似文献   

Elucidating geochemical response of shallow heterogeneous aquifers to CO2 leakage using high-performance computing: Implications for monitoring of CO2 sequestration     

《Advances in water resources》2013

Predicting and quantifying impacts of potential carbon dioxide (CO₂) leakage into shallow aquifers that overlie geologic CO₂ storage formations is an important part of developing reliable carbon storage techniques. Leakage of CO₂ through fractures, faults or faulty wellbores can reduce groundwater pH, inducing geochemical reactions that release solutes into the groundwater and pose a risk of degrading groundwater quality. In order to help quantify this risk, predictions of metal concentrations are needed during geologic storage of CO₂. Here, we present regional-scale reactive transport simulations, at relatively fine-scale, of CO₂ leakage into shallow aquifers run on the PFLOTRAN platform using high-performance computing. Multiple realizations of heterogeneous permeability distributions were generated using standard geostatistical methods. Increased statistical anisotropy of the permeability field resulted in more lateral and vertical spreading of the plume of impacted water, leading to increased Pb²⁺ (lead) concentrations and lower pH at a well down gradient of the CO₂ leak. Pb²⁺ concentrations were higher in simulations where calcite was the source of Pb²⁺ compared to galena. The low solubility of galena effectively buffered the Pb²⁺ concentrations as galena reached saturation under reducing conditions along the flow path. In all cases, Pb²⁺ concentrations remained below the maximum contaminant level set by the EPA. Results from this study, compared to natural variability observed in aquifers, suggest that bicarbonate (HCO₃⁻) concentrations may be a better geochemical indicator of a CO₂ leak under the conditions simulated here.  相似文献   

Mantle source compositions of the Paraná Magmatic Province (southern Brazil): evidence from trace element and Sr–Nd–Pb isotope geochemistry     

L. S. Marques  B. Dupr  E. M. Piccirillo 《Journal of Geodynamics》1999,28(4-5)

An integrated study based on incompatible trace elements and Sr–Nd–Pb isotopes is presented in order to assess the mantle sources involved in the genesis of the Paraná Magmatic Province (PMP) tholeiites. Particular emphasis is given to 33 new Pb isotope and concentration data obtained in representative samples of low-TiO₂ (LTiB) and high-TiO₂ (HTiB) flood basalts that occur in the province. Results show important differences with respect to type and location of these rocks. The LTiB and HTiB from northern PMP exhibit very similar initial Pb isotope ratios (average LTiB vs HTiB: ²⁰⁶Pb/²⁰⁴Pb_i=17.78±0.03 vs 17.65±0.02; ²⁰⁷Pb/²⁰⁴Pb_i=15.53±0.01 vs 15.52±0.01; ²⁰⁸Pb/²⁰⁴Pb_i=38.12±0.03 vs 38.05±0.04). The LTiB from southern PMP, with initial ⁸⁷Sr/⁸⁶Sr_i≤0.7060, show small variation in initial Pb isotope compositions (average ²⁰⁶Pb/²⁰⁴Pb_i=18.20±0.07; ²⁰⁷Pb/²⁰⁴Pb_i=15.61±0.01; ²⁰⁸Pb/²⁰⁴Pb_i=38.32±0.10), which are highly enriched in radiogenic Pb in comparison to the northern PMP analogues. The HTiB from southern PMP have initial Pb isotope ratios (average ²⁰⁶Pb/²⁰⁴Pb_i=17.45±0.09; ²⁰⁷Pb/²⁰⁴Pb_i=15.50±0.01; ²⁰⁸Pb/²⁰⁴Pb_i=37.89±0.03) slightly less radiogenic compared with the HTiB from northern PMP. The data cover a large range of isotope compositions, which are accompanied by systematic changes in incompatible trace element ratios and Sr–Nd isotopes, indicating contributions from different mantle sources. The remarkable chemical and isotope differences between PMP basalts, N-MORB and Tristan da Cunha least evolved volcanics indicate that these asthenospheric sources did not play a significant role in the basalt genesis, suggesting generation from the melting of heterogeneous lithospheric mantle sources. The close similarity between the radiogenic isotopes of the Cretaceous carbonatites that surround the PMP and those of the HTiB rock-types and the LTiB from the northern Paraná suggests the involvement of the same mantle components in their genesis: a dominant EMI end member and a radiogenic isotope enriched component of EMII-type, as some phlogopite-peridotite mantle xenoliths (Japecanga) from the Alto Paranaíba Igneous Province. The latter component seems also to have an important role in the origin of the LTiB from the southern Paraná, where the other end member is highly depleted in radiogenic lead similar to DMM.  相似文献   

Color Removal from Synthetic Textile Wastewater by Sono‐Fenton Process     

Celalettin Özdemir  Muhammed Kamil Öden  Serkan Şahinkaya  Erkan Kalipçi 《洁净——土壤、空气、水》2011,39(1):60-67

In this study, the oxidative decolorization of C.I. reactive yellow 145 (RY 145) from synthetic textile wastewater including RY 145 and polyvinyl alcohol by Fenton and sono‐Fenton processes which are the combination of Fenton process with ultrasound has been carried out. The effects of some operating parameters which are the initial pH of the solution, the initial concentration of Fe²⁺, H₂O₂, and the dye, temperature, and agitation speed on the color and chemical oxygen demand (COD) removals have been investigated. The optimum conditions have been found as [Fe²⁺] = 20 mg/L, [H₂O₂] = 20 mg/L, pH 3 for Fenton process and [Fe²⁺] = 20 mg/L, [H₂O₂] = 15 mg/L, pH 3 for sono‐Fenton process by indirectly sonication at 35 kHz ultrasonic frequency and 80 W ultrasonic power. The color and COD removal efficiencies have been obtained as 91 and 47% by Fenton process, and 95 and 51% by sono‐Fenton processes, respectively. Kinetic studies have been performed for the decolorization of RY 145 under optimum conditions at room temperature. It has been determined that the decolorization has occurred rapidly by sono‐Fenton process, compared to Fenton process.  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   

Effect of Zinc,Copper and Mercury on Channa marulius (HAMILTON)     

B. S. Khangarot 《洁净——土壤、空气、水》1981,9(6):639-649

Static bioassay acute toxicity tests of Zinc, Copper and Mercury were conducted to determine the median lethal concentrations (LC₅₀s) of a freshwater teleost Channa marulius (HAM .) The 96 h LC₅₀ and 95% confidence limits for Zn²⁺ were 25.61 (24.13 … 27.12) mg/l; 0.90 (0.80 … 1.038) mg/l; for Cu²⁺ and 0.314 (0.257 … 0.371) mg/l for Hg²⁺. However, these values decreased at 240 h of exposure and were: 21.09 (18.29 … 24.60) mg Zn²⁺/l; 0.66 (0.568 … 0.841) mg Cu²⁺/l; and 0.131 (0.103 … 0.158) mg Hg²⁺/l. The relative potency ratio of Zn/Hg, Zn/Cu and Cu/Hg suggests that fish were most sensitive to Hg, followed by Cu and Zn ions. The acute toxicities of mixtures of Zn²⁺?Cu²⁺; Zn²⁺?Hg²⁺, Cu²⁺?Hg²⁺ and Zn²⁺?Cu²⁺?Hg²⁺ up to 48 h of exposure were also investigated. The additive index and ranges for Zn²⁺?Cu²⁺ were ?0.241 (-0.577 … 0.054); 0.056 (-0.269 … 0.475) for Zn-Hg; 0.285 (-0.043 … 0.718) for Cu-Hg; and -0.542 (-1.215 … 0.005) for Zn-Cu-Hg. All the mixtures tested showed a greater than additive toxicity because index ranges overlapped zero.  相似文献   

Purification of Drinking Water (Municipal Water Supply) by Activated Charcoal,Potassium Permanganate and Silica Gel Beds Vis a vis to Bleaching Powder and Its Effects on Fish Life     

Smt. Lakshmi  A. K. Srivastava  A. N. Mishra  K. N. Pandey 《洁净——土壤、空气、水》1989,17(3):335-339

A novel method has been developed to purify the municipal water. A pH of 7.05 has been achieved, which is suitable for the drinking purpose. Heavy metal, Pb²+ ions, have been removed to the extent of 0.074 mg/l. This purified water also saves the life of fishes. At the same time the use of bleaching powder in purifying municipal water has been avoided due to its hazardous effect even on fishes.  相似文献   

Determination of Copper in Water Samples after Solid‐phase Extraction Using Dimethylglyoxime‐modified Silica     

Burcu Anilan  Tevfik Gedikbey  Sibel Tunali Akar 《洁净——土壤、空气、水》2010,38(4):344-352

This work describes the modification of silica gel with dimethylglyoxime, in order to prepare an effective sorbent for the preconcentration and determination of copper. The sorption capacity of dimethylglyoxime‐modified silica‐gel (DMGMS) was 71.37 mg g^–1 and the optimum pH for the quantitative recovery of copper was found to be 5.0. The optimum flow rate, sorbent amount, and sample volume were 1 mL min^–1, 300 mg, and 50 mL, respectively. 10 mL of 0.1 mol L^–1 HCl was the most suitable eluent. The detection limit of copper was 6.0 ng mL^–1. The recommended method, for the determination of copper, is simple and reliable, without any notable matrix effect and can be successfully applied to environmental water samples. Copper recovery in the range from 99–100% was obtained from seawater and thermal spring water using this method. The method was applied to standard reference materials, NIST‐1515 (apple leaves) and NIST‐1643e (simulated fresh water), for the determination of copper and the results were in good agreement with certified values.  相似文献   

Comparative Toxicity of Heavy Metals and Interaction of Metals on a Freshwater Pulmonate Snail Lymnaea acuminata (Lamarck)     

B. S. Khangarot  S. Mathur  V. S. Durve 《洁净——土壤、空气、水》1982,10(4):367-375

In static bioassays the toxicity of heavy metal ions against Lymnaea acuminata over 24 … 96 h is tested. The values of the LC_50,96h for the metals tested are, in mg/l: Hg²⁺ ?0.023; Cu²⁺-0.034, Cd²⁺ ?0.872, Ni²⁺ ?2.78, Cr⁶⁺ ?5.97 and Zn²⁺ ?10.49. In the combined solutions of Cu²⁺, Ni²⁺ and Zn²⁺ at least an additive effect of toxicity occurs in the presence of two metals. The same holds for the presence of the three metals; in this case, the relative toxicity against the mixture of two metallic salt solutions appears to be slightly reduced. The acute manifestation of the toxic effect occurs within 48 h, subsequently the relative mortality decreases especially in the mixed solutions.  相似文献   

Auswirkung von Schwermetallgemischen auf die biologische Behandlung naphthalinsulfonsäurehaltiger Abwässer     

H. Pack  D. C. Hempel 《洁净——土壤、空气、水》1997,25(6):306-310

Effect of Mixtures of Heavy Metals on the Biological Treatment of Sewages Containing Naphthalenesulfonic Acid Biological wastewater treatment processes can be destabilized considerably by heavy metals. In this investigation, the effect of loadings of heavy metals on the degradation of naphthalene-2-sulfonic acid (2NS) by immobilized bacteria in continuously operated airlift-loop reactors was studied. Shock loadings with mixtures of cadmium and nickel, or cadmium and zinc, respectively, resulted in increases in inhibition compared to those observed with the single metals. In contrast, the 2NS-degradation was less inhibited by shock loadings with mixtures of nickel and zinc than by the single metal ions. Repeated shock loadings up to 100 mg L^?1 nickel and 1000 mg L^?1 zinc effected an adaptation of the microorganisms. Continuous loadings with up to 10 mg L^?1 cadmium and nickel each, or with 50 mg L^?1 nickel and 210 mg L^?1 zinc, respectively, did not inhibit the degradation of 2NS. The permanent loadings led to an adaptation of the bacteria with an increased biosynthesis of proteins from 0.2 to 0.5 g g^?1 cell dry weight. However, if the immobilized cells were incubated with mixtures of cadmium and nickel, the specific polysaccharide content decreased to less than 0.2 g g^?1 cell dry weight, resulting in a detachment of the biofilms.  相似文献   

Der Einfluß von Erdölkohlenwasserstoffen auf die Primärproduktion des Donauplanktons     

J. Tomajka 《洁净——土壤、空气、水》1985,13(5):615-618

Danube river water samples were saturated with mineral oil, and then the primary production (gross) was determined by means of the light-dark bottle method (oxygen) in situ at depths of 0.1… 1.5 m in comparison with untreated samples. Samples were exposed for half a solar day alternately during the first and second half-days. Investigations carried out between March and October for periods of 14 days showed a mean production of 2.56 g · m^?2d^?1 O₂, which was reduced by 36% due to 12.6 mg/l hydrocarbons. Production decreases with the water depth from 6.2 to 0.9 mg · l^?1d^?1 0₂, whereas the inhibition by hydrocarbons increases from 31 to 41%.  相似文献   

Bolide impacts, acid rain, and biospheric traumas at the Cretaceous-Tertiary boundary     

Ronald G. Prinn  Bruce Fegley Jr. 《Earth and Planetary Science Letters》1987,83(1-4)

Large projectiles impacting the Earth will cause severe shock heating and chemical reprocessing of the Earth's atmosphere. This occurs during atmospheric entry and, more importantly, as a result of the supersonic plume ejected on impact. In particular, very large amounts of nitric oxide would result from the impact of the putative Cretaceous-Tertiary bolide(s). We present models of the shock chemistry, the conversion of NO to NO₂ and thence to nitrous and nitric acids, and the global dispersion of the NO₂ and acids. Two plausible projectiles are considered: an ice-rich long-period comet and a much smaller rock-metal asteroid. The comet produces semi-global atmospheric NO₂ mixing ratios of 0.1% while the asteroid produces these high mixing ratios only in the immediate region of the impact. The comet produces concentrated nitrous and nitric acid rain with apH ≈ 0–1.5 globally. The asteroid produces rain with apH ≈ 0–1 near the impact and≈ 4–5 globally. Immediate environmental effects of these nitrogen species include inhibition of photosynthesis due to extinction of solar radiation by NO₂, foliage damage due to exposure to NO₂ and HNO₃, toxicosis resulting from massive mobilization of soil trace metals, and respiratory damage due to exposure to NO₂. The acid rain decreases the pH of the oceanic mixed layer affecting the stability of calcite with important implications for the survival of calcareous-shelled organisms and for exhalation of CO₂ from the mixed layer to the atmosphere. Longer-term environmental effects perhaps≈ 1000years in duration include a global warming due to the sudden CO₂ injection and the simultaneous extinction of the ocean micro-organisms which normally help remove CO₂ from the atmosphere-mixed layer system. Havens for survival include carbonate-buffered lakes and burrows. This acid rain theory therefore serves to explain the peculiar selectivity of the extinctions seen at the Cretaceous-Tertiary boundary. The first few years of acid rain will lead to massive weathering rates of continental soils characterized by large ratios of the relatively insoluble metals (e.g. Be²⁺, Al³⁺, Hg²⁺, Cu⁺, Fe²⁺, Fe³⁺, Tl³⁺, Pb²⁺, Cd²⁺, Mn²⁺, Sr²⁺) to the more soluble metals (Ca²⁺, Mg²⁺) which should have left a clear signal in the fossils of neritic organisms and in unperturbed neritic sediments near river deltas if such sediments still exist for the Cretaceous-Tertiary time frame.  相似文献   

Removal of Cu2+ and Pb2+ Ions Using CMC Based Thermoresponsive Nanocomposite Hydrogel     

Bengi Özkahraman  Işıl Acar  Serkan Emik 《洁净——土壤、空气、水》2011,39(7):658-664

In this study, carboxymethylcellulose (CMC) based thermoresponsive nanocomposite hydrogel was synthesized for the removal of Cu²⁺ and Pb²⁺ ions from aqueous solutions. To prepare nanocomposite hydrogel, graft copolymerization of N‐isopropyl acrylamide (NIPAm) and acrylic acid (AA) onto CMC was carried out in Na‐montmorillonite (MMT)/water suspension media and ammonium persulfate (APS) used as initiator. The chemical structures of hydrogels were characterized by Fourier transform infrared (FT‐IR) and X‐ray diffraction spectroscopy (XRD). Lower critical solution temperature (LCST), pH responsivity, swelling, and deswelling properties of the hydrogels were also examined. In addition competitive and non‐competitive removal of Cu²⁺ and Pb²⁺ studies were carried out. According to heavy metal sorption studies results, removal capacities of nanocomposite hydrogel for both metal ions were found to be higher than those of pure hydrogel. The analyzed adsorption data showed that the adsorption process of Cu²⁺ and Pb²⁺ could be explained by pseudo‐second order kinetic model. Moreover, according to competitive sorption studies, it is found to be that both hydrogels are more selective to Cu²⁺ ion rather than Pb²⁺.  相似文献