Study of traffic pollution by metals in Seville (Spain) by physical and chemical speciation methods

Eighty-three samples of atmospheric particles were collected at a representative traffic site in the Mediterranean city of Seville during a period of one year. Urban particles were collected on quartz filters with a high-volume sampler coupled with a cascade impactor which separates particles into six size ranges: >10, 10–4.9, 4.9–2.7, 2.7–1.3, 1.3–0.6, and <0.6 m. The total metal content, its distribution by size (physical speciation), and the concentrations of different chemical forms (chemical speciation) in particles less than 0.6 m were determined. The chemical speciation scheme furnished four fractions: soluble and exchangeable metals; carbonates, oxides, and reducible metals; oxidisable and sulfidic metals bound to organic matter; and residual metals. The samples were analysed by ICP–OES for Pb, Ni, Cd, S, Fe, Zn, Cu, Ba, Mn, and V. Gaseous pollutants, traffic intensities, and primary meteorological data provided by the atmospheric and traffic networks were statistically related to the analytical data. Analytical and statistical results from physical and chemical speciation singled out Ba as a valid tracer of vehicular traffic, instead of Pb, in cities with high traffic density. Another important relationship was found between Pb and Cu. Physical speciation of lead showed that the major risk for health was from fine particles less than 2.7 m, because particles between 2.7 and 0.6 m were the size fractions of the total suspended particles with the major mass abundance of lead (mainly particles between 2.7 and 1.3 m) and because particles less than 0.6 m were the fraction of airborne particles most abundant in the urban air. Chemical speciation results showed that special attention must be taken with Ni and Cd concentrations, because of their high potential bioavailability, mainly a result of the high solubility of the chemical forms of Ni in the finest particles.     

Comparison of two calorimetric methods to determine the loss of organic matter in Galician soils (NW Spain) due to forest wildfires

Seven forest soils, Cambisols under pinus, located at Galicia (NW Spain) and affected by forest wildfires were collected to determine the loss of organic matter due to the effect of burning, using calorimetric methods. The enthalpy of combustion, ΔH, of the organic matter of the burnt and the corresponding unburnt soils was calculated from the thermograms obtained with a differential scanning calorimeter (DSC-7, Perkin-Elmer). From these data, the loss of organic matter during the fires was calculated. On the other hand, the organic matter content for each burnt and unburnt soil studied was determined by thermogravimetry (TG) and, in the same way, the loss of organic matter was obtained. High linear, significant correlations were found between the enthalpy of combustion of the soil organic matter (SOM) and the organic matter content measured by thermogravimetry. Consequently, comparison of the loss of organic matter obtained by both methods indicated that the quantitative results are similar. Both techniques allow to determine the degradation level of the soils affected by forest wildfires, taking the loss of organic matter during the fire as a degradation index.     

An automatic field sampler utilising supported liquid membrane (SLM) for on-site extraction of s-triazine herbicides and degradation products: applied to an agricultural region of Ethiopia

A portable and time-integrating field sampler based on the supported liquid membrane (SLM) extraction technique was constructed. Using two programmable syringe pumps and one programmable valve, the sampler could carry out automatic unattended extraction for up to seven extracts, combining the steps of sampling, trace enrichment and clean-up. The sampler was applied to the extraction of four s-triazine herbicides (atrazine, cyanazine, prometryn and terbutryn) and six major degradation products of s-triazines, including three dealkylated products (deethyl deisopropyl atrazine (DDA), deisopropyl atrazine DIA and deethyl atrazine (DEA)) and three hydroxylated products (hydroxy atrazine (ATOH), hydroxy propazine (PROH) and hydroxy terbutylazine (TZOH)). The donor solution was obtained by mixing sample and buffer, consisting of 1?M phosphate buffer at pH 7.0 and 1.7?M NaCl, in the ratio of 19?:?1 (v/v). Extraction was performed by continuously pumping 10?mL portions of donor along the SLM until 3?L of sample had been extracted. The SLM consisted of di-n-hexylether and the acceptor was 1?M HCl. After extract collection, extracts were neutralised with NaOH and buffered with phosphate. Extracts were analysed with HPLC, using a gradient elution consisting of 3.5?mM phosphate and acetonitrile and UV-detection at 220?nm. Enrichment factors in reagent water ranged from 1.3 (for DIA) to 2739 (for terbutryn). The developed field sampler was tested by carrying out 24-h time-weighted on-site extraction of the ten s-triazine target compounds in Hawassa Lake and its tributary river, located in the agricultural region of the Southern Rift Valley of Ethiopia. Atrazine, cyanazine and terbutryn were generally below the method detection limit, while prometryn was frequently found. Overall, s-triazines were not persistent in the studied environment and degradation products of s-triazines were found in higher concentrations than the parent herbicides in both the river and the lake.     

Synthesis and structure determination of N-(alkoxycarbonylsulfenyl)-s-triazine herbicides

Various 2-substituted-4,6-bis(alkylamino)-1,3,5-triazines, 1 , have been found to react with alkoxycarbonylsulfenyl chlorides, 2 , to give the title compounds, 3 . The structural characterization of 3a in the solid state by single X-ray crystallographic analysis established that it is the isomer wherein the methoxycarbonylthio group is attached to the less sterically hindered, exocyclic nitrogen bearing the ethyl group.     

Imidazolinone and triazine herbicides in soils in relation to the complexes formed with Cu(II) ions

Imidazolinone and triazine herbicides are used in many countries and may have a great impact on metal biocycles in soil. This article deals with the dynamics of imidazolinone and triazine herbicides in soils related to the formation of complexes with Cu(II) ions, which can be very stable. The stability constants of the complexes formed by five imidazolinone herbicides and ten triazine herbicides with Cu(II) ions are determined by means of fast, easy, and inexpensive measurements performed by ultraviolet–visible spectroscopy, for imidazolinones, and voltammetry (cyclic and differential pulse), for triazines. Because of the occurrence of dissociation reactions, the determinations were performed at three pH values for imidazolinones and at one pH value for triazines. In aqueous solutions of 5 < pH < 10 (corresponding to the majority of soils of agricultural use), the herbicides form very stable complexes with the Cu(II) ions, the complexes being integrated by two ligands (herbicides) and one copper ion. In conclusion, crops treated with such herbicides in conjunction with Cu(II) salts experience a decrease in its persistence and effectiveness. In addition, the herbicides and the copper ions may pass to the phreatic layer of the soil, increasing the chance of pollution.     

Surface and depth fallout distribution of137Cs and90Sr in soils of Caceres (Spain). Dose commitments due to external irradiation

An analysis has been made of the surface distribution of¹³⁷Cs and⁹⁰Sr in soils of the province of Cáceres (Spain), of some 20.000 km² area, situated on the frontier with Portugal. From the distribution of depth profiles of concentrations of these radionuclides and their fit to a negative exponential, determination was made of the mean values of the respective inventories and of the corresponding¹³⁷Cs/⁹⁰Sr ratio. The external dose rates from the presence of these man-made isotopes in the soil are calculated and compared with that originating from the concentrations of natural radioisotopes.     

Presence of nonylphenol, octyphenol and bisphenol a in two aquifers close to agricultural, industrial and urban areas

Active endocrine disruptors (nonylphenol, octylphenol and bisphenol A) were analysed in 2 aquifers and the corresponding surface waters. They are compounds widely used in industrial processes. The objective of this study was to determine the leaching potential of these compounds in groundwaters and to eventually correlate these levels with surface water samples. The areas sampled were agricultural, close to large cities and with an important industrial activity in the surrounding area. Samples (200 mL) were extracted using off-line SPE with polymeric OASIS 60 mg cartridges. Analyses were performed by gas chromatography-mass spectrometry (GC-MS) using selected ion monitoring (SIM) and full scan for quantification and unequivocal identification, respectively. This paper reports the detection limit for the compounds studied (from 0.001 to 0.030 μg L⁻¹), and method performance as regards to linearity (0.01–1.3 μg L⁻¹), reproducibility (less than 9%) and recovery (84 to 95%). The results from a monitoring program revealed the presence of the target compounds in all samples analysed, at levels of 0.07 and 1.9 μg L⁻¹. The presence of these compounds in groundwater was attributed basically to degradation of inert ingredients present in the formulation of many pesticides or to the increasing application of sludge in agricultural practice, although the infiltration of industrial run-off and wastewater disposal cannot be disregarded.     

Unusual reactivity of (6,9)purinophanes due to stereoelectronic effect

[n](6,9)Purinophanes 2a–c were synthesized and their unusual reactivity toward nucleophiles was explained by the stereoelectronic effect in the fairly rigid tetrahedral intermediate.     

Procedures to define Pu isotopic ratios characterizing a contaminated area in Palomares (Spain)

Plutonium isotopic ratios have been calculated in soils contaminated by the Palomares accident which occurred in 1966 (Almería, Southeastem Spain). Contrasted techniques have been used to determine the radionuclide activities:²³⁸Pu and^238+240Pu were analysed by -spectrometry prior purification on anion-exchange resins, the ratio²³⁹Pu/²⁴⁰Pu was estimated by -spectra deconvolution and²⁴¹Pu was directly measured by liquid scintillation counting and indirectly through quantification of in-grown²⁴¹Am from aged plutonium discs. The mean activity ratios²³⁸Pu/²³⁹Pu,²³⁹Pu/²⁴⁰Pu,²⁴¹Pu/²³⁹Pu, backdated to 1966, were 0.027±0.002 (1), 4.5±0.2 (1) and 8.2±0.8 (1), respectively, characterizing the accident of Palomares as the source term of the measured plutonium.     

Micro volume changes due to Pb(II) and Cu(II) sorption on amorphous Fe(III) hydroxide

Micro volume changes due to Pb(II) and Cu(II) sorption on amorphous Fe(III) hydroxide (AFH) were determined by a dilatometer at pH 4.50. Volume change is attributed to change in hydration status of dissolved and/or suspended substances. The volume of the system increased due to Pb(II) and Cu(II) sorption, suggesting that water molecules hydrated around Pb(II) or Cu(II) ions and AFH were released during sorption. Volume increases due to Pb(II) and Cu(II) sorption were smaller than those due to bulk precipitation of Pb and Cu hydroxides. Precipitation of Pb(II) and Cu(II) was not likely to occur at pH 4.50 in the presence of AFH. In conclusion, Pb(II) and Cu(II) formed an inner-sphere complex on AFH at pH 4.50, keeping hydrated water on the adsorbed species. Adsorbed Cu(II) kept more hydrated water than adsorbed Pb(II) on AFH.     

Raman spectroscopy of the system iron(III)-sulfuric acid-water: an approach to Tinto River's (Spain) hydrogeochemistry

Acid mine drainage is formed when pyrite (FeS(2)) is exposed and reacts with air and water to form sulfuric acid and dissolved iron. Tinto River (Huelva, Spain) is an example of this phenomenon. In this study, Raman spectroscopy has been used to investigate the speciation of the system iron(III)-sulfuric acid-water as an approach to Tinto River's aqueous solutions. The molalities of sulfuric acid (0.09 mol/kg) and iron(III) (0.01-1.5 mol/kg) were chosen to mimic the concentration of the species in Tinto River waters. Raman spectra of the solutions reveal a strong iron(III)-sulfate inner-sphere interaction through the nu(1) sulfate band at 981 cm(-1) and its shoulder at 1005 cm(-1). Iron(III)-sulfate interaction may also be facilitated by hydrogen bonds and monitored in the Raman spectra through the symmetric stretching band of bisulfate at 1052 cm(-1) and a shoulder at 1040 cm(-1). Other bands in the low-frequency region of the Raman spectra are attributed to the hydrogen-bonded complexes formation as well.     

Volume expansion and loss of sample due to initial self-heating in capillary electroseparation (CES) systems

Summary The application of a high voltage, V, in capillary electroseparations following sample injection, can cause loss of analyte if the rate of thermal expansion of the liquid in the capillary (due to ohmic heating) is more rapid than the rate of electro-migration of the slowest moving analyte into the column. We show that the limiting condition for avoidance of this undesirable effect requires that the ramp-up rate for the applied voltage is below a critical value. This critical (maximum) value is given to a good approximation by a simple formula (Eq. (30)). Limiting values of dV/dt are in the region of 1000 V s^–1 when the power loss in the capillary is around 3 W m^–1 (e.g. with a field of 30,000 V m^–1 and a current of 100 A). A detailed mathematical analysis which takes full account of the thermal dependence of key variables, indicates that thermal explosion will occur at fields above a critical value (Eq. (21)). We recommend that commercial CES instrumentation incorporates manual or software led ramp-up voltage control.     

Disruptions in the crystallinity of poly(lauryl methacrylate) due to adsorption on silica

The effects of adsorption of poly(lauryl methacrylate) (PLMA), a side‐chain crystalline polymer, on silica were investigated. Fourier transform infrared spectroscopy and differential scanning calorimetry (DSC) measurements were made on both bulk and adsorbed PLMA. The reversible heat flow rates were observed as a function of temperature and the degree of crystallinity of the samples determined based on the broad melting transitions of the side chains in the surface samples. It was found that adsorption caused a disruption of the side‐chain crystallinity primarily in the tightly bound layer of the polymer, but did not significantly affect its glass transition temperature. A change in the packing of the hydrophobic side chains, as a result of adsorption, was also observed for the tightly adsorbed polymer. These results indicated that PLMA side chains in proximity to the silica surface have different properties from those in bulk PLMA. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 89–96     

Speciation analysis to unravel the soil-to-plant transfer in highly arsenic-contaminated areas in Cornwall (UK)

Two areas near derelict calciners in Cornwall (UK) were chosen to study the uptake of arsenic from arsenic-contaminated soil into indigenous plants (heather, Calluna vulgaris; blackberry, Rubus ulmifulmus; gorse, Ulex europaeus). With total arsenic concentrations in soil ranging from 1240 to 2860 mg kg^?1 at Site 1 (Tuckingmill), no adverse effects on the growth of the plants studied were observed. Very low soil-to-plant transfer factors (0.01 to 0.03) were found although they were much higher when the extractable soil arsenic concentrations were taken into account (0.1 to 1.1). In the central dump area at Site 2 (Bissoe, 9.78% [w/w] arsenic in soil), the only plant to grow was heather, although it was severely impaired. However, heather was thriving at the edge of the dump where higher soil arsenic concentrations were found (10.32% [w/w]), indicating that arsenic is not a growth-limiting factor in itself. Soil-to-plant transfer factors in the range 2 × 10^?5–9 × 10^?4 confirm that arsenic is indeed effectively excluded from uptake, even taking into account extractable soil arsenic concentrations (9 × 10^?4–1.2 × 10^?2).

Extraction of bioavailable arsenic from soil using 0.05 mol L^?1 ammonium sulphate yielded recoveries from 1.18 to 3.34% of the total arsenic, predominantly in the form of arsenate. Extraction of arsenic and its metabolites from plants was achieved with water or a water/methanol mixture yielding recoveries up to 22.4% of the total arsenic, with arsenite and arsenate the predominant arsenic species and a minor fraction consisting of methylarsonic acid, dimethylarsinic acid and trimethylarsine oxide. The identity of the remainder of the non-extractable arsenic species still has to be revealed. Although the data suggest that higher plants synthesise organoarsenic compounds it cannot be excluded that symbiotic organisms have synthesised these compounds.     

Particle size distribution of metals in the atmosphere of Madrid (Spain)

Summary The size distribution of six metals (Cd, Cu, Fe, Mn, Ni and Pb) present in the atmosphere of Madrid was determined in the airborne particulate matter. Samples were collected in an area located in the University Campus in Madrid. Twenty-one samplings were carried out in two different periods: summer 1986 and autumn — winter 1986–87. AAS was employed in the analysis. The particle size distribution of the elements was bimodal. The most toxic metal studied (Cd, Ni and Pb) have extremely high proportions in the smallest particle size range, which can easily enter the respiratory tract lodging in the alveoli. For the metals the enrichment factors based on soil proportions are calculated on each stage. The values are higher for lead, cadmium and nickel, tending to vary from stage to stage, suggesting significant pollution sources.     

Efficient rate enhancement due to intramolecular general base (IGB) assistance in the hydrolysis of N-(o-hydroxyphenyl)phthalimide

The rates of the hydrolyses of N-(o-hydroxyphenyl)phthalimide (1) and N-(o-methoxyphenyl)phthalimide (2), studied at different pH, show that the hydrolysis of 1 involves intramolecular general base (IGB) assistance where the o-O- group of ionized 1 acts as IGB and H2O as the reactant. The rate enhancement due to the IGB-assisted reaction of H2O with ionized 1 is>8x10(4)-fold. Pseudo-first-order rate constant for the reaction of water with 2 is approximately 2x10(3)-fold smaller than the first-order rate constant (0.10 s-1) for pH-independent hydrolysis of 1 within the pH range of 9.60-10.10. Second-order rate constants (kOH) for hydroxide ion-assisted hydrolysis of ionized 1 and 2 are 3.0 and 29.1 M-1 s-1, respectively. The solvent deuterium kinetic isotope effect (dKIE) on the rate of alkaline hydrolysis of 1 and 2 reveals that the respective values of kOH/kOD are 0.84 and 0.78, where kOD represents the second-order rate constant for DO--assisted cleavage of these imides (1 and 2). The value of kwH2O/kdD2O is 2.04, with kwH2O and kdD2O representing pseudo-first-order rate constants for the reactions of ionized 1 with H2O and D2O, respectively.