Estuarine capacity in removal of trace metals from contaminated river water, Southern Caspian Sea

In the present investigation, the flocculation of dissolved Cd, Cu, Ni, Pb, Mn and Zn with initial concentrations of 1, 2.5 and 5 mg/L in Tadjan River water during mixing with the Caspian Sea water has been studied in order to determine estuarine capacity to remove dissolved metals in the accidental contamination of the river. The flocculation process was investigated on a series of mixtures with salinities ranging from 0.1 to 11 p.p.t. The flocculation rates were indicative of the nonconservative behaviour of Cd, Cu, Ni, Pb, Mn and Zn during estuarine mixing. The order of the final flocculation rate of dissolved metals at 1, 2.5 and 5 mg/L of initial metal concentrations in the river water is as follows:Cu (99%)>Cd (95%)>Zn (88%)>Mn (85%)>Pb (83%)>Ni (73%), Cu(95.6%)>Pb(92.4%)>Cd (90%)>Zn(88.4%)>Mn (81.6%)>Ni(78.8%) and Cd (100%)>Cu(88%)>Ni (85.2%)>Pb (84%)>Zn (83.2%)>Mn (81.2%), respectively. The results also revealed that removal of dissolved metals is not influenced by pH changes and precipitation processes. The flocculation rates revealed that the overall dissolved metal pollution loads may be reduced to about 70% up to about more than 90% during estuarine mixing of Tadjan River with the Caspian Sea water.     

Determination of copper in water by means of chalcocite copper ion-selective electrode

The possibility of determination of copper in natural waters was tested by direct potentiometry with chalcocite copper sensitive ion selective electrode. This can be carried out for the copper concentration down to 6 μg l⁻¹ when the standard additions procedure is used. The electrode characteristics was investigated and as a medium was proposed a TFB solution containing Tris, potassium fluoride and potassium nitrate. However at the extreme low concentrations of copper the water samples after addition of TFB should be heated to boiling. In these conditions the accuracy of determination for the average of five measurements is not worse than 25%, and precision is of the order of 20%.     

Determination and speciation of copper and lead in sediments of a Mediterranean river (River Tenes, Catalonia, Spain)

Total concentrations of Cu and Pb and the speciation of these metals in sediments of the River Tenes are studied in order to establish the extent to which they are polluted and their capacity of remobilization. Five samples taken along the river were analyzed, major components of the sediments were studied using XRF and total Pb and Cu content were determined by AAS. In order to test the accuracy of the digestion methods used (triacid attack with nitric, perchloric and hydrofluoric acids or diacic attack with nitric and hydrochloric acids) for the determination of total trace metal, a standard reference material was also analyzed. Triacid attack is proposed to obtain good results. The results show a highly polluted area (1556 mg kg⁻¹ Cu and 1555 mg kg⁻¹ Pb) in the last sampling site analyzed. For metal speciation, the sequential scheme of Tessier et al. was used. From the results obtained, it can be concluded that Cu content in non-residual fraction is bonded mainly to organic matter, whereas non-residual Pb is mainly associated to iron and manganese oxides.     

高含水率有机质河道底泥压缩性状试验研究

河道底泥的压缩性状是影响河道底泥环保疏浚设计及处置的一个关键因素,采集了4条河道的底泥,针对4种城市河道底泥和过氧化氢处理的底泥开展了一系列物理和压缩试验,研究河道底泥的压缩性状,探讨有机质含量对河道底泥压缩性状的影响规律。试验结果表明,河道底泥的有机质含量变化范围大,河道底泥的压缩性状与底泥的物理性状密切相关,与无机质土类似,初始孔隙比和液限孔隙比是河道底泥压缩性状的两个关键控制因素。有机质对底泥压缩性状的影响可以归结于液限孔隙比的改变,有机质含量主要影响河道底泥的液限和比重,进而导致河道底泥重塑屈服应力σ_(yr)~′和压缩性状发生改变。有机质含量越高,液限孔隙比越大,压缩指数越大,呈现出的压缩性越高。     

Determination of the complexing properties of drinking waters toward copper(II) and aluminium(III) by ligand titration

The complexing capacity of some drinking waters for aluminium(III) and copper(II) is determined by a ligand titration with metal ions based on the use of complexing resins. The resins used in the titration are the iminodiacetic resin Chelex 100, the carboxylic resin Amberlite CG50 and the anionic exchange resin AG1X8. They allow the detection of ligands forming complexes of different stability with the metal ions used for the titration, since they have different sorbing properties. After equilibration with the resin, the concentration of the free metal ion in solution is evaluated from the concentration of sorbed metal ion and from the quantity K^*, which is the ratio of the concentration of the metal ion sorbed on the resin to the free metal ion in solution. It strongly depends on the conditions, but it can be evaluated, at the considered conditions, from the sorption equilibria of the metal ion on the resin. The concentration of the ligands in solution and the conditional stability constant are obtained from the Ruzik linearization procedure. Very strong ligands of copper(II) and aluminium(III) were detected in a tap water sample at concentrations ranging from 10⁻⁷ to 10⁻⁶ mol kg⁻¹, and forming complexes having conditional complexation constants K_cI=2.3×10¹⁷ (pH=6.77) and 4.5×10¹⁶ (pH=6.24), respectively, for copper(II) and aluminium(III). Weaker ligands were detected using the less strongly sorbing resins Amberlite CG50 and AG1X8, but at a concentration equal to that of the strong ligands. This was ascribed to the presence of competing metals in solution, not sorbed by the weak resins. Two other drinking waters had completely different complexing properties both towards copper(II) and aluminium(III), containing much weaker ligands.     

N,N-diethyl-m-toluamide transformation in river water

The paper deals with the aqueous environmental fate of N,N-diethyl-m-toluamide (DEET), one of the most widespread and efficient mosquito repellents. The investigation involved monitoring of the DEET decomposition and the identification of intermediate compounds.Initially, control experiments in the dark and under illumination were performed on sterilized and river water spiked with DEET, with the aim to simulate all possible transformation processes occurring in aquatic system. Under illumination, DEET was degraded and transformed into numerous organic intermediate compounds, 37 of which could be identified. Several isomeric species were formed and characterized by analysing MS and MSⁿ spectra, and by comparison with parent molecule fragmentation pathways.These laboratory simulation experiments were verified in the field to check the mechanism previously supposed. River water was sampled and analysed at eight sampling points. Among the transformation products (TPs) identified in river water spiked with DEET, twelve of them were also found in natural river water. The transformation occurring in aquatic systems involved dealkylation, mono- and poly-hydroxylation followed by oxidation of the hydroxyl groups and cleavage of the alkyl chains. Two TPs were principally formed in dark condition, while the others are mainly produced through indirect photolysis processes mediated by natural photosensitizers.     

Toxicities of total and chelex-labile cadmium to salmon in solutions of natural water and diluted sewage with potentially different cadmium complexing capacities

The LC₅₀ for total Cd averaged 4.8 and 8.0 μg1⁻¹ in river water and 33% sewage-treatment-plant effluent (STPE), respectively, and for Chelex-labile Cd, 3.9 and 5.6 μg1⁻¹, respectively. The LC₅₀ values for total Cd were significantly (P < 0.05) different, indicating a reduction in toxicity of Cd in the presence of 33% STPE, presumably due to complexation of Cd²⁺. The similarity of LC₅₀ values for Chelex-labile Cd indicates that that fraction contained toxic species of Cd at approximately the same concentration(s) in both river water and 33% STPE; it is therefore considered a better measure of Cd toxicity than total Cd. Furthermore, mortality was correlated with the concentration of Chelex-labile Cd but not with that of Chelex-nonlabile Cd. Measurements of Cd²⁺-complexing capacity by the Chelex method indicated that toxicity was due, at least in part, to Cd²⁺. Values were less than those obtained by the ion-selective-electrode method; these indicated that toxicity was due only to complexed Cd. Values from both methods were uncorrelated with LC₅₀ values.     

机车用水井改生活饮用水井的可行性探讨

针对石家庄南火车站三口机车用水井的水污染现状,对水的细菌总数和大肠菌群超标、嗅和味以及硬度等方面的治理措施进行了阐述,验证了机车用水井改生活饮用水井的可行性。     

Determination of heavy metals in natural water by the sorption-atomic-absorption method

The procedure for determining Hg, Cd, Pb, Zn, Cu elements in fresh water based on the preconcentration of these metals as complexes using poly-3-pyridyl-5-thioxo-4-allyl-4,5-dihydro-1H-1,2,3-triazole-1-carbodithionic acid with further measurement of atomic adsorption are proposed. The detection limits for metals are 5, 8, 20, 5 and 20 ng/dm³ respectively.     

Linear alkylbenzene sulfonates in river, estuary and bay water

Linear alkylbenzene sulfonates (LAS) in aquatic environments were determined by combined gas-liquid chromatography and mass spectrometry. The ratios of the concentrations of LAS to those of methylene blue active substances in river and bay water were estimated to 0.40–0.85 and less than 0.20, respectively.The percent composition of LAS varied among commercial detergent, river, estuary and bay water. The cause of the variation in the LAS composition among the aquatic environments is discussed.     

Observations on the use of iron(II) complexing agents to fractionate the total filterable iron in natural water samples

Analysis of filtered natural water samples using Fe(II) complexing agents (bathophenanthrolinedisulphonic acid, 2,2′-dipyridyl, ferrozine, TPTZ) and acetic acid-sodium acetate buffer (pH 4.6) showed that the absorbance of the iron(II) complex increased with time both in the presence and the absence of a reducing agent (ascorbic acid, hydroxylammonium chloride). Exposure of the samples to 0.1 M HCl (pH 1.3) for 1 h prior to the addition of the complexing reagents resulted in a stable iron concentration which was designated the acid-extractable fraction of the total filterable iron. The results have implications for the complexometric determination of iron fractions other than total iron after acid digestion.     

Effects of inorganic complexing on the toxicity of copper to Daphnia magna

Effects of carbonate-bicarbonate, orthophosphate, and pyrophosphate on the toxicity of copper (II) to Daphnia magna were studied at constant pH and total hardness. Mortality rates and reciprocal survival times were directly correlated with cupric (Cu²⁺) and copper hydroxy (Cu(OH)n) ion activities as determined by equilibrium calculations. Toxicity was negatively related to activities of soluble copper carbonate (CuCO₃) and other complexes, and was found to be independent of dissolved copper or total copper concentrations.     

Organically-bound copper in lake and river waters in Japan

Organically-bound copper, organic matter concentrations and molecular weight of the organic matter in lake and river waters at Hokkaido in Japan were measured. The interaction between copper and the organic matter was also investigated by using Sephadex gel. The ratio of organicallybound copper to total copper was 10–70%. There was no relationship between the copper complex and the organic matter. From thermodynamic calculation, it was concluded that the variation of the ratio from 10 to 70% depended on the variation of stability constant of copper with the organic matter. The organic matter has molecular weight of 300–700 which resembles fulvic acid originating in river water.     

谈深水井全自动及手动自动供水

针对阿尔及利亚雨水分布不均的气候特点,结合自身工作经验,通过深入试验,设计出了深水井全自动及手动自动供水装置,并对其功能、材料及工作原理进行了介绍,为今后干旱少雨地区施工用水提供了宝贵经验。     

Occurrence, molecular characterization and antibiogram of water quality indicator bacteria in river water serving a water treatment plant

Water pollution by microorganisms of fecal origin is a current world-wide public health concern. Total coliforms, fecal coliforms (Escherichia coli) and enterococci are indicators commonly used to assess the microbiological safety of water resources. In this study, influent water samples and treated water were collected seasonally from a water treatment plant and two major water wells in a Black Belt county of Alabama and evaluated for water quality indicator bacteria. Influent river water samples serving the treatment plant were positive for total coliforms, fecal coliforms (E. coli), and enterococci. The highest number of total coliform most probable number (MPN) was observed in the winter (847.5 MPN/100 mL) and the lowest number in the summer (385.6 MPN/100 mL). Similarly E. coli MPN was substantially higher in the winter (62.25 MPN/100 mL). Seasonal variation of E. coli MPN in influent river water samples was strongly correlated with color (R² = 0.998) and turbidity (R² = 0.992). Neither E. coli nor other coliform type bacteria were detected in effluent potable water from the treatment plant. The MPN of enterococci was the highest in the fall and the lowest in the winter. Approximately 99.7 and 51.5 enterococci MPN/100 mL were recorded in fall and winter seasons respectively. One-way ANOVA tests revealed significant differences in seasonal variation of total coliforms (P < 0.05), fecal coliforms (P < 0.01) and enterococci (P < 0.01). Treated effluent river water samples and well water samples revealed no enterococci contamination. Representative coliform bacteria selected by differential screening on Coliscan Easygel were identified by 16S ribosomal RNA gene sequence analysis. E. coli isolates were sensitive to gentamicin, trimethoprim/sulfamethazole, ciprofloxacin, vancomycin, tetracycline, ampicillin, cefixime, and nitrofurantoin. Nonetheless, isolate BO-54 displayed decreased sensitivity compared to other E. coli isolates. Antibiotic sensitivity pattern can be employed in microbial source tracking.     

Quantitative mapping of chlorhexidine in natural river biofilms

Soft X-ray scanning transmission X-ray microscopy has been applied to map chlorhexidine, a ubiquitous antimicrobial agent, relative to major biochemical components (proteins, lipids, polysaccharides, Ca2+, K+, CO3(2-)) in natural river biofilms. For the first time, bio-accumulation of chlorhexidine in diatoms has been observed unambiguously. The quantitative results show that chlorhexidine bioaccumulated extensively in lipid-rich regions of diatoms and bacteria. Confocal laser scanning microscopy was used to document changes in the biofilm community. The bioaccumulation provides a significant entry point for chlorhexidine into the aquatic food chain. It results in modification of the biofilm community and it impacts the photosynthetic and protozoan species in particular. X-ray microscopy mapping at high spatial resolution is shown to be a powerful tool for studies of antimicrobial agents in the environment.     

Trees and wood: working with natural river processes

A history of land clearance and riparian tree and wood management has resulted in limited riparian woodland and wood along British rivers. However, river management approaches are now being promoted that ‘work with natural processes’ to reduce flood risk through measures intended to restore, protect and emulate the natural function of catchments, rivers, estuaries and coasts. Wood has started to be reintroduced into river channels during river restoration and natural flood management activities, but this needs to be undertaken using appropriate quantities, locations and designs that mimic natural tree‐wood features. This paper reviews the knowledge that is needed to support wood reintroduction activities including (i) the characteristics of the riparian tree species and wood that are present; (ii) the importance of river size relative to that of trees and wood pieces; and (iii) the way trees, wood and geomorphic processes interact across rivers and floodplains of different energy and style.     

Removal of zinc, copper and lead by natural zeolite-a comparison of adsorption isotherms

An uptake of zinc (Zn), copper (Cu), and lead (Pb) from aqueous solutions by ion exchange on natural zeolitic tuff has been studied. The Croatian zeolite clinoptilolite from the Donje Jesenje deposit has been used as a natural ion exchanger. The efficiency of removal is higher for Pb and Cu than for Zn ions. Measured concentrations of Si in the liquid phase identify the detachment of the aluminosilicate structure during ion exchange in the presence of H(+) and OH(-) ions. The adsorption isotherm equations; Langmuir-Freundlich, Redlich-Petersen, Toth, Dubinin-Radushkevich, modified Dubinin-Radushkevich, and Lineweawer-Burk were derived from the basic empirical equations, and used for calculation of ion exchange parameters. The best fitting of experimental results to the proposed isotherms was observed in models that assume that ionic species bind first at energetically most favorable sites, with multi-layer adsorption taking place subsequently.     

Fluoride concentration in the water of the river Cauvery,Karnataka, India

The results of a two‐year study on the fluoride levels in the waters of river Cauvery are presented. It is concluded that the water of this river is unsuitable for domestic use at a few stations along the course because of high fluoride content in the water. Fluoride rich water has also posed a threat to the bird sanctuary at station 4.     

中美供水管井标准中有关井身质量条文的对比研究

随着城市化建设的发展,供水管井作为一种长期的地下取水设备已得到广泛的应用,完善供水管井相关规范显得愈加重要,本文选取了中美5个具有代表性的供水管井技术标准,分析和对比了中美标准中有关井身质量的条文要求,并得出相关结论,为完善供水管井规范提供一定的借鉴意义。