Compounds In Natural Waters Research Articles

Interaction of Alkyltin(IV) Compounds with Ligands of Interest in the Speciation of Natural fluids: Complexes of (CH3)2Sn2+ with Carboxylates

Complex formation by (CH3)2Sn 2+ with acetate (ac), malonate (mal), 1,2,3-propanetricarboxylate (tricarballylate, tca) and 1,2,3,4-butanetetracarboxylate (btc) ligands in aqueous solution is reported. The study has been performed by potentiometry ([H + ]‐glass electrode) at T = 25 °C, and in the 0 < I < 1 mol dm 2 3 ionic strength range. In order to evaluate the salt effects on the formation constants of the complex species, and to contribute to the definition of the chemical speciation of diorganotin(IV) compounds in natural waters where carboxylic ligands are naturally present, interactions of NaCl (which is the major component of all natural fluids), with the components of the systems under investigation have also been considered. A model for the ionic strength dependence of the formation constant was used in order to calculate the values of thermodynamic constants, at infinite dilution, for all the proposed species, by considering hydrolytic species too. A relationship between the charges on the different ligands considered and the stabilities of the complex species formed is also discussed. © 1997 by John Wiley & Sons, Ltd.

Determination of trace levels of taste and odor compounds in water by microextraction and gas chromatography-ion-trap detection-mass spectrometry

A simple, easy-to-perform and sensitive method for routine analysis of trace taste- and odor-causing organic compounds in natural water is presented. The compounds investigated included geosmin, 2-methylisoborneol (MIB), C 6–C 10 linear aldehydes, benzaldehyde, β-cyclocitral, citronella, citral, 2,4-decadienal, 2-methyl-3-heptanone, 5-methyl-3-heptanone, 6-methyl-5-hepten-2-one, geranylacetone, β-ionone, camphene, hexadecane and heptadecane. One liter water samples, salted with 100 g of sodium chloride, were extracted by microextraction using 2 × 3 ml of hexane. The extracts were analyzed by gas chromatographic-ion-trap detection-mass spectrometry (GC-ITD-MS). Mean recoveries from spiked reagent water were 99 ± 7 and 95 ± 8% for MIB and geosmin (spiked with 5–40 ng/l), respectively. For other compounds, recoveries ranged between 81 and 110%, with the exception of hexanal, heptanal and benzaldehyde. The method detection limits were as low as l ng/l for geosmin and MIB, 0.5–6 ng/l for ketones and 5–25 ng/l for other compounds. Recoveries and precision for most of the compounds investigated from spiked river water were similar to those obtained in reagent water. This method was employed for monitoring the occurrence of taste and odor compounds in the Arno River.

Resolution of phenol, o-cresol, m-cresol and p-cresol mixtures by excitation fluorescence using partial least-squares (PLS) multivariate calibration

Determination of phenol, o-cresol, m-cresol and p-cresol has been carried out in mixtures of up to four components by recording excitation fluorescence spectra between 210 and 285 nm with an emission wavelength of 298 nm. The excitationemission spectra of these compounds are strongly overlapped, which does not permit their direct determination without previous separation by conventional methodologies. Here, a method is proposed for the determination of these chemicals by the use of a full-spectrum multivariate calibration method, partial least squares (PLS). The experimental calibration matrix was designed with 18 samples. The concentrations were varied between 100 and 900 μgl −1 for phenol, 150 and 900 μg l −1 for o-cresol and from 80 to 800 μg l −1 for m- and p-cresol. The cross-validation method was used to select the number of factors. To check the accuracy of the proposed method, the optimized model, obtained using PLS-1, was applied to the determination of these compounds in natural water and soil samples previously spiked with different amounts of each chemical.

Evaluation of the goulden large-sample extractor for acidic compounds in natural waters

The Goulden Large-Sample Extractor has received extensive use for monitoring and surveillance surveys of natural waters impacted by pulp and paper mills and agricultural runoff water. However, there are concerns about whether this sampler, which was originally developed for extractions of hydrophobic polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and other organochlorines, is suitable for sampling polar acidic compounds. The sampler was evaluated for recovery of surrogates for resin acids, fatty acids, herbicide acids, and chlorophenols from natural waters. Performance tests conducted in this work indicated that three surrogate compounds with K p (C DCM /C water pH2 ) values from 16,700 to 1,260 were extracted from pH 2-adjusted 20-L water samples with an average recovery of 83.6%. The surrogate compounds with K p values less than 1,000 were extracted with significantly lower recoveries. The variability ranged from 10 to 36% relative standard deviation. Recoveries and variability compared favorably with reported recoveries and variabilities for neutral pesticide surrogates. Specific performance criteria (percent recoveries ± standard deviation, number of determinations in parentheses) observed for the surrogates 2,4,6-tribromophenol, heptadecanoic acid, O-methylpodocarpic acid, dichlorophenylacetic acid, and 4-bromophenol were 89.5 ± 24.0 (17), 82.8 ± 21.7 (18), 78.4 ± 14.8 (18), 41.9 ± 8.5 (16), and 22.1 ± 8.1 (19), respectively. Low recoveries of the 4-bromophenol surrogate may be due in part to side reactions with diazomethane. As a result, 4-bromophenol is not recommended as a surrogate. These values can be used to provide guidelines for acceptable surrogate recoveries and validation of extractions of polar acidic compounds.

Determination of phenolic compounds in natural waters by liquid chromatography with ultraviolet and electrochemical detection after on-line trace enrichment

The eleven phenolic EPA priority pollutants were determined by liquid chromatography followed by UV and electrochemical detection. Modified on-line trace enrichment was used to detect lower concentrations of phenolic compounds, which enables stronger sorbents to be used without broadening the peaks. PLRP-S and a highly cross-linked styrene-divinylbenzen copolymer were compared for the on-line enrichment. Higher breakthrough volumes were obtained with the latter sorbent but the selectivity was lower. The performance of the methods developed was checked with tap and river water and the methods studied enabled phenolic compounds at levels of 0.1 μg 1 −1 to be determined in real samples. The repeatability and reproducibility between days ( n = 5) for real samples spiked at 1 μg 1 −1 were lower than 10%.

Characteristics on the determination of dissolved organic nitrogen compounds in natural waters using titanium dioxide and platinized titanium dioxide mediated photocatalytic degradation

The oxidation of dissolved organic nitrogens (DONs) in natural waters using the photocatalytic degradation with titanium dioxide (TiO 2) and platinized titanium dioxide ( Pt TiO 2 ) is applied to the conventional determination of DONs in natural waters. By the photocatalytic degradation with TiO 2 and Pt TiO 2 , DONs were effectively converted to inorganic nitrogens such as ammonium, nitrate and nitrite within a shorter reaction time compared with the simple photooxidation method without catalyst. The photocatalytic activity of Pt TiO 2 was superior to that observed with simple TiO 2. The ammonium generated from DONs was oxidized to nitrite and nitrate under the aerobic condition with catalyst. The results of initial formation rates of inorganic nitrogens suggested that the nitrate and nitrite were directly generated from DONs, in addition to the formation route of nitrate and nitrite via ammonium. DONs in natural waters were effectively decomposed to inorganic nitrogens, and the concentration of DON in natural waters determined by the photocatalytic degradation method was good agreement with that determined by the wet oxidation method using persulfate as an oxidizing agent. The blank values observed in the photocatalytic degradation method were negligibly small in comparison with the wet oxidation method. The oxidation procedure using the TiO 2 and Pt TiO 2 was powerful method for the determination of DON in natural water.

Speciation of selenium and arsenic compounds in natural waters by capillary zone electrophoresis after on-column preconcentration with field-amplified injection

A method for the separation and determination of selenium and arsenic compounds by capillary zone electrophoresis (CZE) was developed. On-column enrichment of selenium and arsenic was performed by stacking large volumes of samples injected onto the column with the field-amplified injection technique. Over a 100-fold preconcentration for selenium and arsenic compounds could be achieved within 3.7 min. This method was applied to the determination of selenium and arsenic species in real water samples. The detection limits were below 25 ppb. The relative standard deviations for the determination of selenium and arsenic species in water samples were in the range 4.0 to 15.6%.

Liquid chromatography of phenolic compounds in natural water using on-line trace enrichment

Two packing materials, C18 and PLRP-S, are studied for on-line trace enrichment of phenolic compounds in water. Various precolumns of different internal diameter are also tested and the addition of an ion-pair reagent to increase retention and thus, breakthrough volumes of phenolic compounds, is studied. Best results are obtained when a PLRP-S precolumn is coupled on-line with a C18 analytical column and DAD detector. Addition of TBA considerably increases breakthrough volumes. In contrast, when a C18 precolumn is used, breakthrough volumes are lower and it is impossible to determine TCP and PCP, under the experimental conditions used, because of interference of other nonpolar compounds in the samples. The performance of the system is evaluated with river and tap water and the preconcentration of 10 ml of sample in a PLRP-S precolumn involves a linear range between 1 μg 1−1 and 20 μl−1 and limits of determination between 0.5 μg l−1 and 1 μg l−1 are obtained.

Sampling Techniques for Organic Substances in Surface Waters

Abstract A crucial step in the measurement of organic compounds in surface waters is collecting samples representative of the system at the time of sampling and ensuring that no extraneous materials are introduced or target compounds removed during the sampling or transport and storage prior to analysis. The various associations of many organic compounds in natural waters with colloid and suspended materials including microorganisms and algae, have led to fundamental short-comings in describing the sample matrix. Techniques are not generally available at the moment to separate compounds on the basis of their occurrence in associated forms in waters, i.e. the majority of measurements are for “whole” water samples including particulate material. Sampling strategy is primarily determined by factors such as the overall objectives of the measurement, financial constraints and logistic considerations. This paper briefly examines sampling methodologies common to a range of non-Volatile organic compounds with particular attention given to some current problem areas. There is an increasing requirement for intensive sampling to monitor episodic events in rivers that place great demands on current techniques, particularly with respect to sample integrity and stability.

Abiotic transformations of polynuclear aromatic hydrocarbons and polynuclear aromatic nitrogen heterocycles in aquatic environments

The chemical and photochemical oxidation of polynuclear aromatic hydrocarbons (PAHs) and polynuclear aromatic nitrogen heterocycles (PANHs) in water has been critically reviewed. Research needs are identified in order to assess and predict the photodegradation of these compounds in natural water. In particular, more information is needed on the effects of dissolved and particulate inorganic and organic material on the chemical and photochemical oxidation of these compounds in order to understand their behaviour in aquatic ecosystems.

Real-time instrumentation for monitoring water quality: An Australian perspective

Current research in the field of real-time monitoring of water quality is reviewed from an Australian perspective. The desirable features of continuous monitoring instruments and progress in developing multi-parameter real-time instruments are considered first. Then Australian R&D in the three main areas involved in developing a complete instrument are considered; these are sample preparation and handling, new sensors and sensing chemistry, and finally data capture, processing and display. The review identifies five areas where developments are needed: new methods for handling and processing ‘real’ ( i.e. ‘dirty’ and heterogeneous) samples; the development of new sensors to provide more detailed information on particular forms ( e.g. bioavailable) of contaminants; new sensors for detecting and quantifying the presence of low concentrations of toxic organic compounds in natural waters; new real-time methods for assessing the microbial quality of waters; and greater use of chemometrics in processing the signals obtained from complex sample matrices.

Determination of ionic alkyllead compounds in natural waters by differential-pulse anodic stripping voltammetry

Determination of ionic alkyllead compounds in natural waters by differential-pulse anodic stripping voltammetry

Determination of ionic alkyllead compounds in natural waters by differential-pulse anodic stripping voltammetry

A method for the determination of ionic alkyllead compounds in natural waters is described. The method is based on the extraction of organolead compounds in the form of diethyldithiocarbamate complexes into hexane, their re-extraction with dilute nitric acid (pH 1.5), purification of the aqueous acidic solution from interfering co-extracted dithiocarbamate and determination of alkyllead species by differential-pulse anodic stripping voltammetry. The interference of inorganic lead is prevented by coprecipitation of lead ions with barium sulphate. Distributions of trialkyllead species in a water sample under conditions for extraction were calculated from measured stability constants of trialkyllead diethyldithiocarbamates and compared with experimental results. With 2.5 l of water the detection limits for di- and trialkyllead species are ca. 0.5 ng Pb l −1.

Examination for Degradation Paths of Butyltin Compounds in Natural Waters

Examination of individual degradation paths (biodegradation and photolysis) of butyltin compounds (especially tributyltin: TBT) in natural waters was performed. Biodegradation of TBT and dibutyltin (DBT) in an unfiltered sea water in summer is rather fast; their half life is about a week. But pretreatment with glass fiber filter makes the half life of TBT much longer (about 80 days). Photolysis of TBT in sea water by sun light is rapid (half life is about 0.5 days), and faster than in distilled water or in fresh water. Degradation rates of each process for TBT are calculated in various conditions of sea water, and contribution rates are compared. Biodegradation will be the main degradation process in an “SS-rich” area such as a marina, but photolysis will exceed that in a “clean” area. Over all half lives of TBT in sea water vary from 6 days to 127 days considering seasons and presence of SS.

A liquid chromatographic system with multi-detection for the direct analysis of hydrophilic organic compounds in natural waters

A combined analytical LC/HPLC system was developed which allows the direct and continuous determination of organic carbon (OC), inorganic carbon (IC), UV-Vis, fluorescence, and organically bound nitrogen in aqueous solutions in the low μg/l concentration range. The arrangement is well suited as detector for the direct chromatographic characterisation of organic constituents in natural surface- and groundwaters without any sample pretreatment.

Quartz dissolution in organic-rich aqueous systems

Organic electrolytes are a common component of natural waters and are known to be important in many rock-water interactions. The influence of organic electrolytes on silica mobility, quartz solubility, and quartz dissolution kinetics, however, is less well understood. While there is mounting evidence supporting the presence of an aqueous organic-silica complex in natural waters, the significance of this species is difficult to characterize because of competing interactions in mixed inorganic-organic electrolyte environments. In the experiments reported here, the kinetics of quartz dissolution in dilute aqueous organic-acid solutions between 25 and 70°C were investigated to determine the influence of both organic and inorganic electrolytes. Batch-reactor dissolution experiments in inorganic and organic electrolyte solutions were designed to investigate the hypothesis that organic acids at circum-neutral pH accelerate the dissolution and increase the solubility of quartz in water. Results suggest that multi-functional organic acids such as citrate and oxalate accelerate quartz dissolution by decreasing the activation energy by approximately 20%. The increase in dissolution rate was accompanied by a 100% increase in apparent quartz solubility at 25°C. Experiments using inorganic electrolytes, in contrast, increase the rate of quartz dissolution without decreasing the activation energy, and without increasing solubility. From these data, a model for both a solution complex between dissolved organic acid and monomeric silicic acid, and an activated complex on quartz surfaces is proposed. The model suggests that dissolved organic compounds in natural waters at near-neutral pH and low temperatures are capable of accelerating the dissolution of quartz and increasing its solubility.

Determination of picomolar concentrations of carbonyl compounds in natural waters, including seawater, by liquid chromatography

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDetermination of picomolar concentrations of carbonyl compounds in natural waters, including seawater, by liquid chromatographyRobert J. Kieber and Kenneth MopperCite this: Environ. Sci. Technol. 1990, 24, 10, 1477–1481Publication Date (Print):October 1, 1990Publication History Published online1 May 2002Published inissue 1 October 1990https://doi.org/10.1021/es00080a003RIGHTS & PERMISSIONSArticle Views703Altmetric-Citations92LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (638 KB) Get e-Alerts Get e-Alerts

Microbial degradation kinetics of toxic organic chemicals over a wide range of concentrations in natural aquatic systems

AbstractThe degradation kinetics for several toxic organic compounds (p‐cresol, phenol, p‐ chlorophenol, acetone and methanol) exposed to natural aquatic microbial assemblages were examined over a wide range of concentrations. Compounds were added in radiolabeled form and incubated at 25°C for periods ranging from several hours to one day. The results revealed that degradation kinetics were multiphasic for each of the compounds during at least one sampling period, i.e., the kinetic parameters Kt and Vmax increased with increasing substrate concentration. The observed multiphasicity suggests the presence within the natural microbial assemblages of multiple uptake/degradative systems, each with distinguishable kinetic parameters and each dominating degradation at a different substrate concentration range. If the kinetic diversity is ignored and rates of degradation are calculated based on the assumption that kinetics follow simple hyperbolic (Michaelis‐Menten) relationships, then errors as large as 40,000‐fold can result. Thus, our results suggest that models for predicting the persistence of such compounds in natural waters should consider changes in kinetic constants with substrate concentration.

Direct use of high molecular weight polysaccharide by heterotrophic flagellates

In aquatic ecology it is assumed that the heterotrophic (non-photosynthetic) protozoa that are abundant in marine and fresh water cannot compete with smaller-sized bacteria for labile dissolved substrates of low relative molecular mass (Mr), such as simple sugars and amino acids, at the low concentrations found in situ1,2 (typically 1–100 μg litre−1) because of surface to volume considerations. Consequently dissolved organic matter (DOM) is not considered to be a source of nutrition for heterotrophic protozoa, which are thought to be predominantly phagotrophic on bacteria and other small planktonic cells2. But there is no information as to whether protozoa might be able to use DOM of higher Mr. Here I report that heterotrophic flagellates in a salt marsh estuary and in a freshwater pond were able to ingest molecules of the polysaccharide dextran of Mr> 500,000 (500K). Mixed species cultures of estuarine and pond flagellates also showed enhanced growth in the presence of 2,000K, but not 40K, dextran. Compounds with high-Mr are often a large fraction of total DOM in natural waters3,4, and the concentrations (dry weight litre−1) of some types of labile high-Mr compounds in natural waters are equal to, or greater than, those of bacterioplankton5,6. Thus DOM of high Mr may be an alternative food resource for aquatic flagellates. Direct ingestion of high Mr compounds by heterotrophic flagellates would represent a more efficient pathway for returning a portion of DOM to aquatic food webs compared with the DOM-bacteria-flagellate-ciliate microbial loop7.

Methylation of tin(II) by methyl iodide under simulated estuarine conditions in the absence and presence of fulvic acid

This paper describes the methylation of tin(II) chloride and the formation of monomethyltin under conditions that model the estuarine environment. Two sets of factorial experimental designs clarified the significance of pH, salinity, and methyl iodide (MeI) concentration on monomethyltin formation in the absence and presence of fulvic acid (FA). The reactions gave percent yields for monomethyltin of 0.30 to 9.95 in the absence of FA and 0.18 to 4.90 in its presence. No other methyltin product occurred and several potential methylating agents failed to methylate tin(II). Analyses of variance (ANOVA) calculations at the 95% confidence level showed a high significance of MeI and FA concentrations in the methylation reactions. Increasing MeI concentration favors methylation while increasing FA concentration inhibits it. Calculations showed the distribution of tin(II) species was only slightly affected in the pH range of our experiments and was virtually unaffected by salinity and FA concentration. These results suggest that chemical processes can contribute to the formation of methyltin compounds in natural waters.