Application of Non-Destructive X-Ray Fluorescence Spectrometry to the Analysis of Suspended Matter in Sea Water

Abstract

In the framework of remote sensing studies concerning coastal transport of pollution in the Northern Adriatic Sea, a method has been developed for the quantitative determination of sulphur, iron, titanium, calcium, phosphorus, silicon, aluminium, magnesium in suspended matter of sea water.

The suspended material was collected by filtering on millipore membrane filters with pore width of 0.45 μ and directly analysed by X-ray spectroscopy. For calibration dried solution and particulate standard samples were used. Limits of sensitivity and precision of the method are reported.

Correlations between the concentration of these elements and the total suspended matter/chlorophyll are discussed.

The aim is to study the geochemical composition of particulate matter and its variations within the geographical site of the sea basin and the seasonal conditions. The approach is to consider aluminium and the other elements normalized on Al. On the basis of a matrix correlation analyses of some sets of data chosen in the restricted area for investigation, some hypothesis on superficial distribution of clay, carbonate, iron hydrous oxides and other mineral detrites, are taken into account. The results confirm the complex situation existing in the offshore area of the Venice lagoon from a geochemical point of view.

The suspended matter seem to be argillaceous in the Southern part of the investigated area and semi-argillaceous with hydrous oxides and carbonates in the Northern part which is influenced by the Piave river.     

Kinetic Analysis Applied to Iron in a Natural Water Model Containing Ions,Organic Complexes,Colloids, and Particles

Abstract

Kinetic analysis using complex formation reactions is applied to “mixtures” containing (variously), Fe³⁺, Fe²⁺, iron complexed to a fulvic acid, hydrous oxide colloids, and non-settleable particulate iron. Such mixtures can be directly resolved if the kinetics of complex formation reactions are pseudo first order and differences among rate constants are large enough. At pH = 4, it is found that fulvic acid causes substantial reduction of Fe³⁺ to Fe²⁺ and that it causes complete dissolution and depolymerization of colloidal and particulate iron at 1:1 ratio. Addition of one equivalent of phosphate causes precipitation of ferric phosphate even in the presence of fulvic acid. This system is very useful for modeling natural water because the kinetic technique allows convenient analysis of components of varying particle size. The present results are strongly indicative of the role of fulvic acid in mediating metal ion chemistry in natural water.     

Simultaneous Filtration and Solid-Phase Extraction Combined with Large-Volume Injection in GC/MS for Ultra-Trace Analysis of Polar Pesticides in Surface Water

A method combining simultaneous filtration and solid-phase extraction (SPE) with large-volume injection (LVI) in gas chromatography/mass spectrometry (GC/MS) was developed to determine 13 polar pesticides in surface water. The selected pesticides - 4 organophosphorus, 7 organonitrogens and 2 triazine degradation products - were extracted from 0.5-L samples of filtered and raw water using cartridges filled with a silica-bonded material (1 g of ISOLUTE triazine, C-18) and a depth filter. No obstruction was observed during the extraction of raw water drawn from the St. Lawrence River (concentration of suspended particulate matter (SPM) ranging from 2 to 58 mg L^?1). Overall percent recoveries were satisfactory for all the target pesticides (>60%) except desisopropyl-atrazine (more polar), which varied from 29 to 46% according to sample pH. The coefficient of variation was below 10% for the majority of the target pesticides and detection limits ranged from 0.1 to 0.8 ng L^?1. Applied to real samples drawn from the St. Lawrence River, this method allowed for the detection of atrazine, cyanazine, desethyl-atrazine (DEA), desisopropyl-atrazine (DIA), metolachlor and simazine, at concentrations of 6 to 91 ng L^?1. Using atrazine and metolachlor as examples, the correlation between filtered and raw water samples was more significant for the former (r = 0.87) than for the latter (r = 0.67). Temporal variations in atrazine and metolachlor in filtered water drawn from the St. Lawrence River, for example, were similar whether using the established method, based on liquid-liquid large-volume extraction (LVE) combined with GC/NPD analysis, or the one proposed herein. The latter method, however, systematically found atrazine concentrations 62% higher than those obtained by the older one, applied to the same field samples. Thus, the switch to the new analytical method will require the application of a correction factor to the atrazine concentration time series acquired with the previously used method.     

The radiation dose and distribution coefficient of 210Po and 210Pb concentrations in aquatic environs of major rivers of coastal Karnataka

The activity of ²¹⁰Po and ²¹⁰Pb was measured in different matrices of aquatic ecosystem of the major rivers of Coastal Karnataka viz, Kali, Sharavathi and Netravathi. The environmental samples such as surface water, suspended particulate matter and sediment have been subjected to analyses. The activity of these two radionuclides were determined by radiochemical separation of ²¹⁰Po and counting the activity using a ZnS(Ag) alpha counter. The activity ratio of ²¹⁰Po and ²¹⁰Pb and correlation between the activity of these radionuclides were studied. From the measured concentration of ²¹⁰Po and ²¹⁰Pb, the internal Committed Effective Dose to the population for the study area was calculated. The distribution coefficient K_d between water, suspended particulate matter and sediments have been calculated to understand the distribution and accumulation of these radionuclides in different matrices of the aquatic environment.

     

Monitoring of carcinogenic PAHs in air under mild–warm ambient temperatures: relative importance of vapour- and particulate-phase analyses in assessing exposure and risk

Atmospheric polycyclic aromatic hydrocarbons (PAHs) are often determined by collecting only the particulate phase. The aim of this study was to ascertain in the field to what extent not collecting the vapour phase may affect the exposure assessment and the risk assessment for carcinogenic PAHs, under ambient temperatures typical of Southern Europe. PM₁₀ 24-h samples were collected in Rome every two months throughout one year on a filter backed by two polyurethane foam sections. Daily mean temperatures during sampling reached 31°C, with hourly maximum values up to 36°C. While four-ring PAHs were found in the vapour phase to a large extent, the calculated annual means of five-ring PAHs, including benzo[a]pyrene, were not affected significantly by the amounts collected as vapour phase. By using the “toxicity equivalence factor” approach, the carcinogenic risk overall attributable to particle-bound PAHs accounted for at least 97% of the risk attributable to total (particulate + vapour phase) PAHs.     

A method to investigate the interaction of rare earth elements in aqueous solution with metal oxides

A method is described which can be used to investigate the interaction of dissolved metals with particulate material. Low level concentrations (10^–9M) of rare earth radiotracers were used to investigate their sorption onto synthetic mineral oxide surfaces. The preparation of rare earth radiotracers by neutron activation is discussed in detail. A kinetic approach was employed to investigate the interaction of dissolved metals and suspended mineral oxides. Amorphous iron oxyhyroxide, a phase commonly found in nature, was used in sorption experiments carried out in seawater at pH 7.8 and 2°C. Results of this study indicate a high affinity of the rare earth elements (REE) for the iron oxide surface (evidenced by fast uptake and high partition coefficients) and reveal a fraction between light and heavy REE.     

Distribution of Heavy Metals in Water and Soil Solutions Based on Colloid-Size Fractionation

The distribution of heavy metals Cr, Ni, Zn, Cu, Cd, and Pb among the truly dissolved (molecular weight cutoff <1 kD), colloidal (1 kD-0.20 µm and 0.20-0.45 µm) and particulate (>0.45 µm) fractions was investigated in the soil solution and surface water. In 15 soil solutions heavy metals were mainly present in the truly dissolved fraction (<1 kD) with occasional exceptions. And a good correlation was also found between the concentrations of metals in the truly dissolved fractions and the cation exchange capacity of soils. As for the surface water samples, the distribution pattern was more complicated one depending on metal properties and sampling sites.     

Coprecipitative Preconcentration and Differential Pulse Cathodic Stripping Voltammetric Determination of Selenium (IV)

Abstract

A DPCSV procedure for the determination of selenium (IV) with a prior preconcentrative coprecipitation on iron (III) hydroxide has been developed. The experimental conditions for coprecipitation of selenium (IV) onto iron (III) hydroxide, viz. pH, iron (III) concentration, volume of aqueous phase and selenium concentration, were optimized. The coprecipitated selenium (IV) is dissolved in 10 ml of 0.1 M HCl and analysed using DPCSV in the presence of copper (II). Selenium concentrations as low as 10–100 ng present in 500 ml of the aqueous phase could be determined. The method is precise and has been applied to the analysis of sea water and reference material samples.     

A preliminary study to assess the effect of some seawater components on the speciation of plutonium

Since Pu(IV) and Pu(V) exhibit very different sediment sorption behaviour, the transport of Pu in the aquatic environment is dependant upon oxidation state and the rate of interconversion between the species. A number of laboratory experiments have been carried out to determine possible parameters which influence the rate of Pu redox reactions and the extent of sorption by suspended particulate in the marine environment. Results suggest that, although the initial sorption of Pu(IV) did not appear to be dependant upon the major cations present in seawater, the sorption of Pu(V) was decreased in the presence of Ca²⁺ and Mg²⁺ ions. Both the rates of oxidation of dissolved Pu(IV) and reduction of dissolved Pu(V) increased with increasing suspended particulate concentration.     

Investigating the innate selectivity issues of methane to methanol: consideration of an aqueous environment

The higher reactivity of the methanol product over the methane reactant for the direct oxidation of methane to methanol is explored. C–H activation, C–O coupling, and C–OH coupling are investigated as key steps in the selective oxidation of methane using DFT. These elementary steps are initially considered in the gas phase for a variety of fcc (111) pristine metal surfaces. Methanol is found to be consistently more reactive for both C–H activation and subsequent oxidation steps. With an aqueous environment being understood experimentally to have a profound effect on the selectivity of this process, these steps are also considered in the aqueous phase by ab initio molecular dynamics calculations. The water solvent is modelled explicity, with each water molecule given the same level of theory as the metal surface and surface species. Free energy profiles for these steps are generated by umbrella sampling. It is found that an aqueous environment has a considerable effect on the kinetics of the elementary steps yet has little effect on the methane/methanol selectivity-conversion limit. Despite this, we find that the aqueous phase promotes the C–OH pathway for methanol formation, which could enhance the selectivity for methanol formation over that of other oxygenates.

Consideration of the selectivity of methane to methanol in the aqueous phase with AIMD.     

Vertical Distribution of Particulate Mercury as Measured on a Meteorological Observation Tower (213m)

Abstract

The concentration of mercury in airborne particles was determined in samples collected at heights of 1m and at 175m up the Meteorological Observation Tower (213m) at the Meteorological Research Institute, Tsukuba between August 1985 and April 1986. The concentrations of particulate mercury at the two heights were compared with gaseous mercury levels at a height of 10m and with other chemical components in the particles. The concentrations of particulate mercury at both heights showed no positive correlation with those of gaseous mercury, total suspended particles, sulfate, chloride, sodium or calcium. However, there was some positive correlation between particulate mercury and nitrate concentrations especially at 175m; the concentrations of these components were found to be high when the wind direction was southwesterly. These results suggest that these components were transported from the Tokyo Metropolitan area.     

Ultraviolet Photolysis and Ortho-Phthalaldehyde-Mercaptoethanol Derivatization of Pharmaceuticals for Enhanced Fluorescence Detection in HPLC

Abstract

Several classes of nitrogenous pharmaceutical were examined for fluorescence after ultraviolet (UV) radiation induced photolysis followed by reaction with o-phthalaldehyde-2-mercaptoethanol (OPA-MERC), and after UV photolysis alone. Photolyses were examined in water, mixtures of methanol/water (1:1), and acetonitrile/water (1:1). Acetone was assessed as a photosensitizer to enhance photolysis and fluorescence response. Flow injection analysis and high-performance liquid chromatographic techniques were used for several pharmaceuticals. The analytes were subjected to UV photolysis and reaction with OPA-MERC reagent for generation of fluorophores that responded to fluorescence detection. During photolysis, solvent type as well as the presence of photosensitizers seem to play a significant role in the formation of primary amines and fluorophores. Photochemical transformation products of some of the pharmaceutical chemicals are proposed. Analytical figures of merit were determined for some analytes. This fluorescence detection approach is applicable for a number of pharmaceuticals at nanogram level.     

An interlaboratory comparison on whole water samples

The European Water Framework Directive 2000/60/EC requires monitoring of organic priority pollutants in so-called whole water samples, i.e. in aqueous non-filtered samples that contain natural colloidal and suspended particulate matter. Colloids and suspended particles in the liquid phase constitute a challenge for sample homogeneity and stability. Within the joint research project ENV08 “Traceable measurements for monitoring critical pollutants under the European Water Framework Directive 2000/60/EC”, whole water test materials were developed by spiking defined amounts of aqueous slurries of ultra-finely milled contaminated soil or sediment and aqueous solutions of humic acid into a natural mineral water matrix. This paper presents the results of an European-wide interlaboratory comparison (ILC) using this type of test materials. Target analytes were tributyltin, polybrominated diphenyl ethers and polycyclic aromatic hydrocarbons in the ng/L concentration range. Results of the ILC indicate that the produced materials are sufficiently homogeneous and stable to serve as samples for, e.g. proficiency testing or method validation. To our knowledge, this is the first time that ready-to-use water materials with a defined amount of suspended particulate and colloidal matter have been applied as test samples in an interlaboratory exercise. These samples meet the requirements of the European Water Framework Directive. Previous proficiency testing schemes mainly employed filtered water samples fortified with a spike of the target analyte in a water-miscible organic solvent.     

Detector for particulate polycyclic aromatic hydrocarbons in water

It is estimated that most polycyclic aromatic hydrocarbons (PAHs) in environmental water are not dissolved but rather in particulate form. Nevertheless, the currently available optical detectors are not suited for proper sampling of solid PAHs. A new setup for direct sampling and quantification of suspended particulate PAHs in water is suggested. It is based on a polymeric film that has the capability of dissolving PAH particulates, coupled to a traditional laser-induced fluorescence probe. Kinetics and performance of two sampling modes have been studied: bulk sampling, by immersing the probe into the water, and surface sampling, by laying the film on the water surface. The latter method has proved to be more sensitive; however, it is diffusion-limited. Linear calibration plots have provided quantification over a wide concentration range with detection limits in the ppb range (these could be improved by using a modified probe). The effects due to other particulates in water have been studied and only little interferences have been observed. The possibility of analysis of PAH mixtures has been addressed and it has been concluded that multivariate analysis is needed.     

Contamination Pétrolière de la Microcouche de Surface du Golfe de Fos-sur-mer (Mer Méditerranéee)

Abstract

In a general study on the petroleum contamination of the Fos-sur-mer Gulf (Mediterranean Sea), the surface microlayer was sampled. We present here the first results reported up to date in this area, based on a sampling carried out with a rotating PVC drum at 3 stations in May 1985.

Very high hydrocarbons concentrations were sometimes observed in the surface film, which appears more heterogeneous than the underlaying water column (0.5-2m). Water samples were filtered through fiberglass filters (0.5-1 μm). Both dissolved and particulate phases were separately extracted and analysed, providing evidence that suspended particles are the major vector for the accumulation and the transport of petroleum pollutants in these neritic waters.

The petroleum origin of “total hydrocarbons” fractions is confirmed by GC and HPLC which reveal characteristic features for n-alkanes and polynuclear aromatic hydrocarbons. HPLC analysis of polar (non-hydrocarbons) fractions could indicate their formation from petroleum components. Furthermore, the comparison with the underlying waters shows that volatilization and biodegradation are the major processes affecting hydrocarbons distribution in these superficial waters.

Biological data (bacteria, chlorophylls, ATP and energetic charge) were simultaneously measured and indicated an important inhibition of phyto- and bacterio- neuston regarding to the planktonic organisms.     

Free surface-induced bilayer smectic A phase in polar liquid crystals

Abstract

Here the influence of the free surface on both a thick (semi-infinite) layer and a thin freely suspended film of a polar liquid crystal is investigated. It is shown that within the temperature range of the monolayer smectic A phase (S_A1 ) the interaction between polar molecules and the free surface of the liquid crystal gives rise to a bilayer smectic A, a structure with long range antiferroelectric order (S_A2 ) in the surface region of the semi-infinite layer. The dependence of the bilayer smectic order parameter on the strength of the interaction between the constituent molecules and the free surface as well as temperature and the distance to the free surface are determined. Sufficiently far from the S_A1 -S_A2 transition the latter dependence has an exponential character and the depth of the S_A2 phase penetration into bulk liquid crystal is equal to the longitudinal correlation length for the bilayer smectic A structure fluctuations in the S_A1 phase. However, near the S_A1 -S_A2 transition the bilayer smectic order parameter decays non-exponentially and more rapidly with increasing distance to the free surface. In addition, it is found that the bilayer S_A2 phase can form several smectic layers at the free surface of a semi-infinite polar liquid crystal layer with the S_A1 phase. Finally, it is shown that in a freely suspended film the free surface-induced S_A2 phase can completely occupy the volume of the sample. Hence in a freely suspended polar liquid crystal film the S_A1 -S_A2 transition occurs with decreasing film thickness.     

Comparative Study for the Removal of Oxadiazon from Aqueous Solutions by Adsorption on Chitosan and Activated Carbon

Abstract

In the present investigation, chitosan and activated carbon are used as adsorbents for the removal of oxadiazon from aqueous solutions. The analyzing system was a gas chromatograph equipped with mass selective detector. The equilibrium studies are systematically carried out in a batch process, covering various process parameters that include agitation time, adsorbent dosage, and pH of the aqueous solution. Also, the relationship between extraction of oxadiazon and volume of aqueous/organic phase as well as the effect of inorganic salt were investigated. Adsorption behavior was found to follow Freundlich and Langmuir isotherms. The adsorption mechanism is described by a pseudo-second-order kinetics.     

Determination of chlorophenols in environmental water samples using directly suspended droplet liquid-liquid-liquid phase microextraction prior to high-performance liquid chromatography

A new sample preparation method named directly suspended droplet liquid-liquid-liquid phase microextraction was used in this research for determination of three chlorophenols in environmental water samples. The analytes (2-chlorophenol, 3-chlorophenol and 4-chlorophenol) were extracted from 4.5?mL acidic donor phase, (pH 2, P1) into an organic phase, 350?µL?of benzene/1-octanol (90?:?10 v/v, P2) and then were back-extracted into a 7?µL droplet of an basic (pH 13) aqueous solution (acceptor phase, P3). In this method, contrary to the ordinary single drop liquid-phase microextraction technique, an aqueous large droplet is freely suspended on the surface of the organic solvent, without using a microsyringe as supporting device. This aqueous microdroplet is delivered at the top-centre position of an immiscible organic solvent which is laid over the aqueous donor sample solution while the solution is being agitated. Then, the acceptor phase containing chlorophenols was withdrawn back into a HPLC microsyringe and neutralised by adding of 7?µL HCl 0.1?M. The total amount was eventually injected into the HPLC system with UV detection at 225?nm for further analysis. Parameters such as the organic solvent, phases volumes, extraction and back-extraction times, stirring rate and pH values were optimised. The calibration graphs are linear in the range of 10–2000?µg?L^?1 with r?≥?0.9973. The enrichment factors were ranged from 115 to 170, and the limit of detection (LOD, n?=?7) varied from 5 to 10?µg?L^?1. The relative standard deviations (RSDs, n?=?5) were found 6.8 to 7.4 at S/N?=?3. All experiments were carried out at room temperature, (22?±?0.5°C).     

Analysis,fate studies and monitoring of the antifungal agent clotrimazole in the aquatic environment

The analysis and presence of clotrimazole, an antifungal agent with logK _OW > 4, was thoroughly studied in the aquatic environment. For that reason analytical methods based on gas chromatography–mass spectrometry and liquid chromatography–tandem mass spectrometry were developed and validated to quantify clotrimazole with limits of quantification down to 5 and 1 ng/L, respectively. Both methods were compared in an intercalibration exercise. The complete mass-spectrometric fragmentation pattern could be elucidated with the aid of quadrupole time of flight mass spectrometry. Since clotrimazole tends to adsorb to laboratory glassware, studies on its adsorption behaviour were made to ensure the appropriate handling of water samples, e.g. pH, storage time, pretreatment of sampling vessels or material of the vials used for final extracts. The phenomena of adsorption to suspended matter were investigated while analysing different waste-water samples. Application of the methods in various investigated wastewater and surface water samples demonstrated that clotrimazole could only be detected in the low nanogram per litre range of anthropogenic influenced unfiltered water samples after acidification to pH 2.     

Heterogeneous conversion of calcite aerosol by nitric acid

The reaction of nitric acid with calcite aerosol at varying relative humidities has been studied under suspended particle conditions in an atmospheric reaction chamber using infrared absorption spectroscopy. The reactant concentration in the chamber, as well as the appearance of gas phase products and surface adsorbed species, was spectroscopically monitored before and after mixing with CaCO(3) (calcite) particles. The interaction with HNO(3) was found to lead to gas phase CO(2) evolution and increased water uptake due to heterogeneous conversion of the carbonate to particulate nitrate. The reaction was enhanced as the relative humidity of the system was increased, especially at relative humidities above the reported deliquescence point of particulate Ca(NO(3))(2). The measured reaction extent demonstrates that the total calcite particulate mass is available for reaction with HNO(3) and the conversion process is not limited to the particle surface. The spectroscopy of the surface formed nitrate suggests a highly concentrated solution environment with a significant degree of ion pairing. The implications of the HNO(3) loss and the formation of the particulate nitrate product for atmospheric chemistry are discussed.