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 250 毫秒
1.
Rainwater samples were collected in the western sector of Mexico City (MC) and at Rancho Viejo (RV), 80 km west-south-west of MC, from 2001 to 2005, and Orizaba City (OC), about 90 km from the Gulf of Mexico, where rainwater collections were only possible on some weekends in 2001. Rainwater samples were treated in the field, and analysed by fluorescence at the laboratory. The volume-weighted mean concentration (VWMC) of H2O2 was 13.2 μM at RV, and 11.2 μM in MC, for the period 2001–2005. The highest VWMC was observed in OC (21.6 μM). The VWMCs for each year were 9.5, 14.4, 11.5, 16.7, and 14.3 μM at RV, and 12.2, 12.2, 14.3, 11.8, and 9.9 μM in MC, for 2001–2005, respectively. Hydrogen peroxide in rainwater correlated significantly and negatively with sulfate in both MC and RV, but not, however, in OC. This study confirmed that H2O2 concentration in rainwater is controlled by a complex combination of rain intensity, washout processes and in-cloud formation of H2O2, acting simultaneously. This was suggested by the fact that rain intensity seemed to predominate in certain rain fractions of a rain event, while washout processes seemed to predominate in other fractions of the same rain event.  相似文献   

2.
Rainwater concentrations of either ammonium or nitrate were sufficient to stimulate chlorophyll a (chl a) production in bioassay experiments using Gulf Stream surface water collected off North Carolina during the summer of 1991. Previous studies primarily examined inshore waters and did not address the impact of rainwater ammonium. An increase in chl a occurred within 1 d of the addition of synthetic rainwater (2 or 5% rainwater, 98 or 95% seawater) containing up to 10 M ammonium; this increase was followed by a decrease in chl a the following day. A similar response to nitrate addition (5% addition of 20 M nitrate rain) was observed. In separate experiments, natural rainwater having nitrate and ammonium concentrations less than those in the experimental synthetic rain yielded a greater chl a response than synthetic rain when added at similar dilutions (0.5 to 5.0% rain). The maximum dissolved inorganic nitrogen concentration in the enriched seawater in these bioassays was 1.8 M; prior to enrichment the maximum was < 0.4 M. Bioassay experiments begun 2 d after a major storm event (sustained NE winds with gusts to 13 m s-1 and ca. 390 mol m-2 inorganic nitrogen deposition from rain) showed a chl a increase in response to addition of natural rainwater, but not to synthetic rainwater with similar dissolved inorganic nitrogen concentration. These results suggest that phytoplankton stimulants, in addition to nitrate and ammonium, exist in natural rain but not in the synthetic rain used in these experiments.  相似文献   

3.
The stability of H+, NH 4 + , and PO 4 3? ions in rainwater samples was in vestigated under different conditions cf storage and transport. Microbiological and physicochemical processes account for changes. Suppression of microbiological activities in deposition networks using conventional analyses may be achieved by adding AgCl-powder and by cooling to +4 °C.  相似文献   

4.
A field project encompassing wet-only rainwater sampling was initiated as a bilateral Fiji/Australia activity. Normally, biweekly samples were collected, using a wet-only rainwater sampler, and analysed for H+, Na+, K+, Mg2+, NH4 +, Cl, NO3 , SO4 2–, PO4 3-, methane sulphonic acid, oxalic acid, formic acid and acetic acid. The pH of the rainwater ranged between 5.730 and 4.480 with an average value of 5.176, slightly lower than the pH of unpolluted rainwater saturated with atmospheric CO2(pH = 5.650). Na+and Clwere the major ions with average concentrations of 98.15 M and 109.57 M respectively. There is an excellent correlation between the cation sum (average 147.71 eq L-1) and the anion sum (average 142.12 eq L-1) attesting to the quality of the data generated. This paper presents the detailed results of the study for a relatively clean remote island site in Suva, Fiji, latitude 18° 09 S, longitude 178° 27 E, height 6 m, and outlines prospects for further work.  相似文献   

5.
Rainwater samples were collected from Tamale town in the 1997 and 1998 rainy seasons. During this period road construction in the Tamale area resulted in the generation of suspended dust in the atmosphere. Analysis of the samples for major ions showed elevated levels of Cl. Ion ratios with Cl (Na+/Cl, K+/Cl, Ca2+/Cl/Cl Mg2+/Cl and SO4 2–/Cl) in rainwater samples were higher than the corresponding ratios in seawater. Some samples also showed elevated concentrations of Fe, Mn, Al and Zn, all of which except Zn showed a correlation with the dry periods between rainfall events. Consequently, it was concluded that dust generated from lateritic soils was probably the major cause of the increase in concentration of these metals. Aluminium and Fe concentrations were observed to be higher than the World Health Organization drinking water guide limits.  相似文献   

6.
Stable isotope ratios of hydrogen and oxygen of water are useful tracers of the hydrological cycle. For example, isotopes monitor the evapotranspiration in vegetated areas, local snow ice processes and stream water flow processes. δ18O and δD in rainwater reflect the processes of evaporation, condensation and precipitation. Heavy rains thus modify the stable isotope ratio of ground water, stream water and transpiration water vapor. However, the controlling factors of δ18O and δD are not clear. Here we analyzed the inorganic ion concentration and stable isotope ratio in 38 normal rainwater and 15 heavy rainwater samples were collected in Shinjuku, Tokyo, Japan, during four years from October 2012 to December 2015. Results show a decrease in δ18O and δD values with the total rainfall amount, thus highlighting the amount effect. δ18O and δD volume-weighted mean values in typhoon heavy rain were higher than the values estimated from amount effect, whereas δ18O and δD volume-weighted mean values in urban-induced heavy rain were lower. Typhoon heavy rain has high Na+ ratio and stable isotope ratios, while urban-induced heavy rain has low Na+ ratio and stable isotope ratio.  相似文献   

7.
Uranium is a very toxic and radioactive element. Removal of uranium from wastewaters requires remediation technologies. Actual methods are costly and ineffective when uranium concentration is very low. Little is known about the enhancement of sorption of uranyl ions by phosphate ions on aluminosilicates. Here, we studied sorption of uranyl acetate on red clay in the presence of phosphates. The concentration of U(VI) ranged 0.0001–0.001 mol/L, whereas the concentration of PO4 3? was constant at 0.0001 mol/L. We designed a new method for the analysis of ternary surface complexes. We observed for the first time a remarkable improvement of U(VI) sorption on red clay under the influence of phosphates. We also found that at least two different ternary surface complexes U(VI)–phosphate–clay are formed in the sorbent phase. The complexation of UO2 2+ cations by phosphate ligands in the sorbent phase was confirmed by the X-ray photoelectron spectra of U 4f electrons.  相似文献   

8.
This paper reports the results from a study of the organic composition of rainwater collected at Tianhe district of Guangzhou city, P.R. China, during the dry season. Several special setups of a pyrex bottle with a glass funnel were used for the collection of the rainwater. Three fractions (aliphatics, PAHs and fatty acids) were separated from the total extracted organic compounds and identified with GC-MS. The molecular diagnostic ratios were utilized for the source reconciliation. The aliphatic hydrocarbon and the biomarkers (triterpanes and steranes) distribution show a characteristic of the petrochemical source in the rainwater samples. The PAHs diagnostic ratios [e.g. MP/P, MPI, Fl/ (Fl + Py)] indicated vehicular emissions. The fatty acids ratios (e.g. C18:1/C18:0 and C18:2/C18:0) reflect the contribution of cooking emissions, while the higher plant waxes play little part. Moreover, the values of MP/P, MPI, BaA/(BaA + CT) and BeP/(BeP + BaP) reflected the origin of the long-distance transportation to some extent. On the whole, for the dry season rainwater, all molecular diagnostic ratios indicated the complexity of the organic composition of the rain, which have the characteristics of both a local emission contribution and a long-distance transportation contribution.  相似文献   

9.
为评价由酸雨、酸性矿山排水等环境污染导致的水体酸化及水体重金属联合作用对水生生物的生态毒性效应,研究了不同pH值(pH=3、4、5、6、7和7.8)条件下Cu2+对斑马鱼胚胎发育的影响。结果表明,酸性水体及Cu2+单一存在时,酸对斑马鱼胚胎24h半数效应浓度值EC50为pH=3.65,Cu2+(pH=7.8)对斑马鱼胚胎24h-EC50为0.267mg·L-1;当水体酸化及水体中的Cu2+共存时,较低的pH对Cu2+的生物毒性起协同作用,表现为随溶液pH的降低,各浓度Cu2+对斑马鱼胚胎的24h凝结率显著增高(P24h致死率=0.001),而斑马鱼胚胎96h孵化率显著降低(P96h孵化率=0.002),且不同浓度的Cu2+之间的生物毒性效应存在显著性差异(P24h致死率=0.0321;P96h孵化率=0.0028)。这说明酸性水体和Cu2+都显著影响斑马鱼胚胎的发育,且Cu2+在酸性水体中对斑马鱼胚胎的毒性显著增强。因此,在受重金属Cu2+污染的地区,如同时受到酸雨或酸性矿山排水等较低pH值和Cu2+的双重胁迫,较低浓度的Cu2+就能够对水生生物的生殖发育及水生生态系统产生严重的影响和危害。  相似文献   

10.
Adsorption of diazine dye safranine O (SO) in the presence of Cs+ and Sr2+ ions was investigated onto natural and synthetic zeolites in order to predict competition of cationic organic species with their radionuclides, which are the main fission products released into the environment. Adsorption of SO was measured up to the 40th day and the surface-diffusion coefficients (Ds) were estimated by applying Nernst–Planck approximation based on a homogeneous-surface-diffusion model. The values of Ds were 10 times higher on natural zeolite than those of synthesized zeolite from fly ash (FA) under hydrothermal conditions. Similarly, distribution coefficients (KD) were considerably higher on the clinoptilolite-type natural zeolite. The zeolitized product of FA is mainly composed of analcime and sodalite. SO adsorption on natural zeolite was not influenced by Cs+ and Sr2+ ions, but it decreased at high concentrations on synthetic zeolite. The higher influence of the Sr2+ ions on SO+ adsorption showed that they compete with each other for the same adsorption sites. These results suggested that natural zeolite cannot be used for remediation of wastewater polluted with Cs and Sr radionuclides in the presence of organic cations, whilst FA zeolite has a potential for Sr removal.  相似文献   

11.
The influence of the type of clouds that produce precipitation in the rainwater composition was analyzed. Logroño, a remote station in the North of Spain was chosen for the analyses. Results prove that the rainwater composition from Cumulonimbus is different to the composition of the rainwater from the other clouds. In addition, the source of NO3 ? and SO4 2? is studied in the different types of clouds. It is shown that the source is the soil except Stratocumulus formed from Cumulus in which the source is the gas‐particle conversion.  相似文献   

12.
In this work, a new procedure for the enrichment of the trace amount of Cu2+, Ni2+, Co2+, Pb2+, Fe2+, and Zn2+ ions based on the utilization of multiwalled carbon nanotubes (MWCNT) modified with 2-(2-hydroxy-5-nitrophenyl)-4,5-diphenyl imidazole as chelating agent prior to their determination by flame atomic absorption spectrometry has been described. The influence of effective parameters including pH, amount of ligand and MWCNT, composition of eluent, and coexisting ions on recoveries of understudy metal ions was examined. At the optimum pH of 5.0, all metal ions were quantitatively sorbed onto the proposed solid phase and completely desorbed with 8?mL of 5.0?mol?L?1 HNO3. The detection limit of Cu2+, Co2+, Ni2+, Pb2+, Fe2+, and Zn2+ ions was 1.7, 2.4, 2.3, 2.9, 2.8, and 1.4?µg?L?1, while the preconcentration factor was 63 for Cu2+ and 94 for the other metal ions and relative standard deviations between 1.8 less than 3.0%. The proposed procedure was applied for the analysis of various samples.  相似文献   

13.
To investigate the potential use of Lentinus edodes (L. edodes) residue for Cd2+ adsorption, poly alcohol Na alginate (PVA) was applied to immobilize it. The parameters including contact time, pH, adsorbent dosages, and coexisting metal ions were studied. The suitable pH for immobilized L. edodes was 4?C7 wider than that for raw L. edodes (pH 6?C7). In the presence of Pb2+ concentration varying from 0 to 30 mg·L?1, the Cd2+ adsorption ratios declined by 6.71% and 47.45% for immobilized and raw L. edodes, respectively. While, with the coexisting ion Cu2+ concentration varied from 0 to 30 mg·L?1, the Cd2+ adsorption ratios declined by 12.97% and 50.56% for immobilized and raw L. edodes, respectively. The Cd2+ adsorption isotherms in single-metal and dual-metal solutions were analyzed by using Langmuir, Freundlich, and Dubinin-Radushkevich models. The Cd2+ adsorption capacities (q m) in single-metal solution were 6.448 mg·L?1 and 2.832 mg·L?1 for immobilized and raw L. edodes, respectively. The q m of immobilized L. edodes were 1.850 mg Cd·g?1 in Cd2+ + Pb2+ solution and 3.961 mg Cd·g?1 in Cd2+ + Cu2+ solution, respectively. The Cd2+ adsorption processes subjected to both adsorbents follow pseudo-second-order model. Mechanism study showed the functional group of L. edodes was -OH, -NH, -CO, and PVA played an important role in metal adsorbing. Mining wastewater treatment test showed that PVA-SA-immobilized L. edodes was effective in mixed pollutant treatment even for wastewater containing metal ions in very low concentration.  相似文献   

14.
The acid-base status of two sea urchins, Psammechinus miliaris (Gmelin) and Echinus esculentus (L.) during experimental emersion has been investigated. Sea urchins were collected from the Firth of Clyde between August and September 1987. The carbon dioxide capacity of the coelomic fluid of P. miliaris was greater than that of E. esculentus, although both were low and only marginally greater than that of sea water. The pH of the coelonic fluid was also low (7.05 to 7.17) and was influenced mainly by the internal partial pressure of CO2 (PCO 2). Acid-base disturbance in the coelomic fluid of both species during emersion, although minimal, was more pronounced in E. esculentus than in P. miliaris and was due primarily to an increase in the internal PCO 2, although there was an increase in the concentration of L-lactate in the coelomic fluid of E. esculentus. The coelomic fluid of both species was in a state of perfectly compensated respiratory acidosis. An increase in the concentration of divalent ions (Ca2+ and Mg2+) may be related to the dissolution of the test as a source of carbonate buffer.  相似文献   

15.
Quality of groundwater in the Yarmouk basin, Jordan has been assessed through the study of hydrogeochemical characteristics and the water chemistry as it is considered the main source for drinking and agriculture activities in the region. The results of the relationship between Ca2+ + Mg2+ versus HCO3? + CO32?, Ca2+ + Mg2+ versus total cations, Na+ + K+ versus total cations, Cl? + SO42? versus Na+ + K+, Na+ versus Cl?, Na+ versus HCO3? + CO32?, Na+ versus Ca2+, and Na+: Cl? versus EC describe the mineral dissolution mechanism through the strong relationship between water with rocks in alkaline conditions with the release of Ca2+, Mg2+, Na+, K+, HCO3?, CO32?, SO42?, and F? ions in the groundwater for enrichment. Furthermore, evaporation processes, groundwater depletion, and ion exchange contribute to the increased concentration of Na+ and Cl? ions in groundwater. Anthropogenic sources are one of the main reasons for contamination of groundwater in the study area and for increasing the concentration of Mg2+, Na+, Cl?, SO42?, and NO3? ions. Results show the quality of groundwater in the study area is categorized as follows: HCO3? + CO32? > Cl? > SO42? > NO3? > F? and Na+ > Ca2+ > Mg2+ > K+. In conclusion, the results of TDS, TH, and chemical composition showed that 26% of the groundwater samples were unsuitable for drinking. About 28% of groundwater samples in the study area have a high concentration of Mg2+, Na+, and NO3? above the acceptable limit. Also, based on high SAR, 10% of the groundwater samples were not suitable for irrigation purposes.  相似文献   

16.
As a biomass agricultural waste material, coconut shells were used for the preparation of high-quality modified activated carbon. Chemical modification of the surface of the prepared activated carbon is done by oxidation using H2O2 and HNO3, respectively. The surface area and pore volume of the coconut shells activated carbon are increased by the chemical modification, and followingly the removal of the metals is improved. The structural morphology and composition of the modified activated carbon coconut shells (MACCS) were evaluated by Fourier transform infrared (FTIR) spectra, thermogravimetric analysis–differential thermal analysis (TGA-DTA), scanning electron microscope (SEM), X-ray diffraction (XRD), surface area analysis (SAA), X-ray fluorescence (XRF), and carbon, hydrogen, nitrogen, and sulfur (CHNS) elemental analysis. The prepared MACCS has reasonably good chemical stability. The influence of solution pH, contact time, adsorbent dosage, adsorption temperature, initial metal concentrations, and interfering ions on the adsorption performance of the investigated ions onto the prepared sorbent was examined by a batch method. The selectivity sequence for sorption of Eu3+, Ce3+, Sr2+, and Cs+ ions on MACCS was found to be Eu3+?>?Ce3+?>?Sr2+?>?Cs+. The saturation capacities of MACCS for the studied metal ions were found to be 136.84, 85.55, 69.85, and 60.00?mg?g?1 for Eu3+, Ce3+, Sr2+, and Cs+ ions, respectively. The thermodynamic parameters, ΔH°, ΔS°, and ΔG° were also evaluated.  相似文献   

17.

A resin synthesized from tamarind kernel powder possesses high selectivity for metal ions. Distribution coefficients for some metal ions has been determined by the batch method. The influence of pH on ion exchange capacity and K d value of metal ions were studied. The resin has been characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, chemical composition and ion exchange capacity (IEC). The selectivity order is Pb2+?>?Cu2+?>?Fe2+?>?Zn2+?>?Ni2+. Removal of metal ions from the aqueous solution and from effluents of a steel mill has been studied.  相似文献   

18.
Agricultural activity is one of the most important sources of aerosol particles. To understand the mass distribution and sources of aerosol particles and their inorganic water-soluble ions in a suburb farmland of Beijing, particle samples were collected using a microorifice uniform deposit impactor (MOUDI) in the summer of 2004 in a suburb vegetable field. The distribution of the particles and their inorganic water-soluble ions in the diameter range of 0.18–18 μm were measured. The dominant fine particle ions were SO4 2?, NO3 ?, and NH4 +. The association of day-to-day variation of the concentration of these ions with temperature, humidity, and solar radiation suggested that they are formed by the reaction of NH3 released from the vegetable field with the acid species produced from photochemical reactions. Fine particle K+ is likely from vegetation emission and biomass burning. Coarse particles like Ca2+, Mg2+, NO3 ?, and SO4 2? are suggested to come from the mechanical process by which the soil particle entered the atmosphere, and from the reaction of the acid species at the surface of the soil particle. The results show that fertilizer and soil are important factors determining the aerosol particle over agricultural fields, and vegetable fields in suburban Beijing contribute significantly to the aerosol particle.  相似文献   

19.
A laboratory-scale investigation was performed to study arsenic (As (V)) removal by negatively charged GE-HL nanofiltration (NF) membrane in simulated drinking water. Effects of As (V) concentration (0–200 μg·L?1), pH, and co-ions and counter-ions were investigated. The NF membrane presented good stability, and the rejection rates exceeded 90%. The rejection rates of As (V) decreased with the increase of As (V) concentration, while it increased with the increase of pH (reached 96% at pH 6.75). Moreover, a negative relationship was observed between the co-existing ions of Cl?, Na+, SO 4 2? , and Ca2+ and the removal of As (V), in which bivalent ions presented more significant effects than monovalent ions.  相似文献   

20.
In this research, we evaluated the toxic effect of metal ions on mycelial growth and phosphate-solubilising activity of soil-borne micromycetes isolated from the Phragmites australis rhizosphere using Pikovskaya-agar plates supplemented with four metal concentrations. The diameter growth rate (DGR) decreased as the metal concentration rise for all tested fungi. Trichoderma atroviride had the fastest growth rate (1.48?cm2?day?1) and was the least susceptible to Al3+, Cd2+, Cr3+, Cu2+ and Pb2+ with a median effective concentration (MEC50) of 12.19, 0.48, 4.51, 11.44 and 50.05?mM, respectively. Aspergillus japonicus was the most tolerant to Co2+, Ni2+ and Zn2+, with MEC50 values of 3.36, 1.095 and 2.34?mM, respectively. Penicillium italicum was the most tolerant to Cr6+ (MEC50?=?0.677?mM). The ability to solubilise phosphate remained, despite the decrease in the DGR, and P. italicum and Penicillium dipodomyicola had the highest Phosphate Solubilisation Indexes (PSIs) at 1.97 and 2.12, respectively. In particular, P. italicum recorded the highest PSI of all the studied isolates at 0.62?mM Cr3+ (PSI?=?4.74). A. japonicus and T. atroviride were the most tolerant isolates to all tested metals, which suggests that these isolates are promising candidates for further study with regard to mycoremediation and biofertilisation of metal-polluted soils.  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