Minor Anions Research Articles

Geochemical characterization of spring waters from the Tinerkouk region, southwestern Algeria

ABSTRACT The present work focused on the geochemical characterization of spring water in the Tinerkouk region in southwestern Algeria. The suitability of the spring water for drinking was assessed using its physicochemical parameters, which included pH, total dissolved solids, major and minor cation and anion compositions, and electrical conductivity. These parameters were compared to Algerian regulations and WHO (World Health Organization) standards to see if the water met the requirements for both spring water and mineral water according to the prevailing standards in force. For this purpose, 43 spring water samples were collected from Tinerkouk region and especially from mineral water unit of Tazliza, during the period 2009-2022. The results obtained for pH, conductivity, sulfate, chloride, nitrate, sodium, and potassium, showed that the water samples from all the sampled springs were acceptable for consumption and within the acceptable limits in accordance with specified criteria, except for Oudghagh, Fatis, and Benzita. However, at these sites, TDS, conductivity, nitrates, and chlorides exceeded the acceptable values. It was also noted that, the spring water from the Tazliza unit is classified as excellent for drinking purposes and meets the permissible limits defined by the legislation for mineral and spring waters. The results also indicate that the predominant chemical facies of the Tazliza spring waters are chlorinated and sulfated sodium and potassium.

CCQM-K161 "Anions in Seawater"

Main textAnions or nutrients in seawater are very important targets for oceanographic research and environmental monitoring of contaminations. Quantification of minor and trace anions in seawater has always been a challenge for the extremely high salinity, disparate levels of analyte and matrix ions, and even need to be measured at levels close to the detection limits of the method performance. Evidence of successful participation in formal, relevant international comparisons is needed to support calibration and measurement capability claims (CMCs) made by the national metrology institutes (NMIs) and designated institutes (DIs).The CCQM-K161 Anions in Seawater was organized by the Inorganic Analysis Working Group (IAWG) of the Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology (CCQM) to assess the abilities of the NMIs and DIs for the accurate determination of minor and trace anions in seawater. The measurands covered chloride (16 mg/g-25 mg/g), sulfate (1 mg/g-4 mg/g), bromide (30 mg/kg-100 mg/kg), nitrate (1 mg/kg-5 mg/kg) and phosphate (60 µg/kg-300 µg/kg). Twelve national metrology institutes and designated institutes participated in this key comparison. Participants were requested to evaluate the mass fractions, expressed in mg/g for chloride and sulfate, mg/kg for bromide and nitrate, and µg/kg for phosphate (as phosphorus) in a mixed natural seawater that was spiked with the phosphate. A variety of techniques including isotope dilution inductively coupled plasma mass spectrometry (IDMS), isotope dilution gas chromatography-mass spectrometry (ID-GC-MS), ion chromatography (IC), UV visible spectrophotometry (UV-Vis), flow injection analysis (FIA) was used by the participants for the determination.The NIST Decision Tree was used to assign the KCRV estimate and to calculate the degrees of equivalence of each participants following the IAWG Guidance on Using NIST Decision Tree for Comparison Reporting from 30 June 2023.Successful participation in CCQM-K161 demonstrates measurement capabilities for determination of anions in seawater. Considering the IAWG Core Capability Matrix, this material falls into the matrix challenge called 'High salts content', which corresponds to the CCQM amount-of-substance category sea water, and so will support CMCs for the anions in a mass fraction range from 60 µg/kg to 25 mg/g.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Geochemical appraisal of fluoride contaminated groundwater in the vicinity of a coal mining region: Spatial variability and health risk assessment

The present study focuses on the geochemical characteristics and quality of potable groundwater in mining area, particularly with reference to fluoride (F−). Spatial variability in physicochemical parameters of groundwater samples (32) collected from Katras block coal mine area was analysed. Parameters such as total hardness, total alkalinity, calcium (Ca2+), sodium (Na+), bicarbonate (HCO3-) and concentration of fluoride (F−) were found to be exceeding the Bureau of Indian standard (BIS) guidelines. The contributions of major cations and anions were found to be in the order of Ca2+ (44 %) > Na+ (40 %) > Mg2+ (15 %) > K+ (1%) and HCO3- (50 %) > Cl− (34 %) > SO42- (14 %) respectively, and aggregates of minor anions such as nitrate and fluoride constituted approximately 2% respectively. Piper trilinear diagram suggested dominance of Ca-Mg-Cl, CaCl and NaCl type of water, resulting in hard brackish water. Alkaline pH and high bicarbonate concentration provide suitable conditions for release of fluoride from fluorite and fluorapatite. Water quality index (WQI) indicated that most of the samples (53 %) of the study area belonged to "poor water", 41 % to "good water" and one sample was categorized as "excellent" type of water. Moreover, only one sample was classified as "not suitable for drinking purposes" with WQI value of 322.94. Health risk assessment for ingestion and dermal routes were carried out for various age groups based on chronic daily dose and hazard quotient, and results indicated that fluoride uptake through ingestion was more severe. Infants (6−12 months) were found to be at a higher risk when compared to higher age group population. To improve the existing groundwater quality and reduce associated human risks, suitable water management measures is also recommended.

Penentuan Secara Serempak Kadar Minor Anion (F-, Cl-, NO2-, Br-, NO3-, SO42– dan PO43-) dalam Sampel Air Botol Kemasan dengan Teknik Kromatografi Ion Kinerja Tinggi

Analytical and separation conditions for the simultaneous determination of minor anions (F - , Cl - , NO 2 - , Br - , NO 3 - , SO 4 2– , and PO 4 3- ) using ion chromatography technique have been optimized. In this study, ion chromatography with a suppressed conductivity detection system was applied to determine the ionic species with high sensitivity. By these conditions, it has been targeted in the determination of the seven anions in bottled drinking water samples. With concentration of 6 mM Na 2 CO 3 and 1,2 mM NaHCO 3 were used as the eluent combination for all determinations. All the above anions could be completely determied and eluted were less than 30 min. All anions were displayed symmetrical peak shapes as in the chromatograms. The correlation coefficient ( r ) varies between 0.9995 and 1 for the above seven anions, whereas the detection limits calculated at S/N= 3 were 0.02–0.45 µg/L. The obtained optimum conditions were then applied to the simultaneous determination of minor anions in 6 bottled drinking water samples with different brands. From the overall drinking water samples which was collected commersially in North Maluku, there were no minor anions concentration exceeding the specified quality standards.

Surface Water Quality in a Contrasted Land-Use River Catchment

To evaluate the current state quality of the surface water resources in a river catchment near the city of Leiria (Central Portugal), a water sampling programme was designed and has been carried out since September of 2017. The land uses of the basin area were also studied. The three sampling sites are located in the river Lis catchment, downstream from the river spring to the city of Leiria, and in the Ribeira do Sirol tributary. The sampling programme was performed according to ISO 5667 standards. At each sampling site and twice a year, the field parameters, the concentration of dissolved gases (O2 and CO2) and the alkalinity were measured in the water. As the Lis river discharge is widely variable, flow parameters were also measured. The composition of surface water was determined in dissolved and particulate material, being the samples filtered at site. The major and minor constituents, cations (Ca, Mg, Na, K, NH4 and Fe) and anions (HCO3, Cl, SO4, PO4, F, NO3 and NO2) were analysed. Data of the winter campaign show that the hydrochemical facies of Lis River water are mainly Ca-HCO3. The chemical species are in dissolved forms and there is no evidence of nitrites, phosphates or fluoride in the surface waters. The concentration of Na, K and Cl, Mg and SO4, increase downstream, after the Ribeira do Sirol tributary, whose basin is mainly of agricultural land use. The water of River Lis in the urban area of Leiria shows evidence of a mixture of the spring water and of the Ribeira do Sirol water, with little contributions of other water sources in the urban area, pointing to a greater concern with respect to sanitation and good environmental practices in the city of Leiria.

Formation, Structure, and Composition of Methylaluminoxane.

The structurally ill-characterized methylaluminoxane (MAO) is the activator of choice in olefin polymerization catalysis. We have carried out large scale and systematic quantum chemical calculations to simulate the thermodynamics of its formation by controlled hydrolysis of trimethylaluminum (TMA), extending the studies up to 25 Al atoms, and thus, to the real size domain of MAO. In agreement with previous postulates on its structure, MAO is shown to favor cage-like structures, which commonly contain associated TMA, regardless of size or shape. The sites containing associated TMA are reactive, and explain the function of MAO as a catalyst activator. The compositions of MAOs show overall agreement with experiments, and exhibit structural transitions from chains to rings to sheets to eventually cages as a function of size. The most stable cage structure is obtained for a composition of (MeAlO)16 (Me3 Al)6 , which is in precise agreement with mass spectrometric studies of corresponding anions, and adapts a tubular molecular structure with a molecular weight of 1360 g mol-1 . Our mass spectrometric measurements enable detection of both major and minor anion species.

Altervalent substitution of sodium for calcium in biogenic calcite and aragonite

Sodium concentrations in biogenic CaCO3 are several thousands of parts per million, and, on a molar basis, Na is among the most abundant constituent minor element in these carbonates. Nevertheless, the chemical form of Na in CaCO3 is not well constrained. We used synchrotron X-ray spectroscopy to identify the dominant molecular host sites for Na in biogenic calcite and aragonite precipitated by corals, bivalves, and foraminifera. We also used the K-edge X-ray absorption near-edge structure to investigate the chemical environment of Na in biogenic calcium carbonates and identify the altervalent substitution of Na into Ca sites in the lattice structures of calcite and aragonite. Minor cation and anion concentrations in biogenic CaCO3 suggest that the principal substitution mechanism involves charge compensation through the creation of CO32− vacancies. The mostly homogeneous Na concentrations in the skeletal microstructures of the various biota we examined indicate that environmental and biological controls, such as temperature, skeletal microstructure, and calcification rates, have only minor influences on skeletal Na concentrations. A decrease of Na:Ca ratios with increasing age of foraminiferal shells picked from a Quaternary sediment core, indicates progressive release of Na, which suggests that structurally-substituted Na in biogenic CaCO3 is readily leached during burial diagenesis. Whereas the sediment that undergo diagenesis release some Na back to the water column, sodium co-precipitation in biogenic CaCO3 serves as a potential sink of Na for the ocean.

Hydrogeochemical Analysis and Evaluation of the Groundwater in the Haramaya Well Field,Eastern Hararghe Zone, Ethiopia

Knowledge of the origin and hydrogeochemical composition of groundwater is very important for the sustainable development of groundwater resources in the present state of art. It is imperative to regularly monitor the quality of groundwater and develop means to protect it. Accordingly, this study was aimed to conduct a hydrogeochemical analysis and evaluation of the groundwater in the Lake Haramaya well field. The water samples taken from the well field were analyzed for six physicochemical parameters (temperature, conductivity, TDS, total hardness, pH, and turbidity), major cations and anions, minor anions and trace metals using standard procedures, and the results were compared with the national and international standards. The analysis conducted using the GW-Chart software has also shown that the origin of the well water in the study area is shallow fresh groundwater with a major geochemical composition of calcium carbonate, which was found to be in line with the previously developed geological and hydrogeological maps of the site. According to the laboratory results, the levels of calcium ion in most of the samples were found to be very high. Moreover, the calcium ion concentrations in most of the wells, especially in the wells nearby the limestone outcropping area, were found to be by far beyond the maximum contaminant standards. Therefore, these facts can assure that the origin of the groundwater in the study area is shallow and calcium carbonate rich aquifer. Consequently, the groundwater in the area was evaluated as hard water.

Evolution of groundwater chemistry on shallow aquifer of Yogyakarta City urban area

Since 1980s, accelerated by urbanization, Yogyakarta City was shifting to many directions defined by main road networks and service centres. Urbanization has transformed rural dwellings to become urban settlements and generated urban agglomeration area. Until now, new business centres, education centres and tourism centres are growing hand in hand with new settlements (formal or informal) without proper provision of water supply and sanitation system. This condition increase the possibility of groundwater contamination from urban wastewater and a change of major chemistry of groundwater as shallow unconfined aquifer is lying under Yogyakarta City. To prove the evolution of groundwater chemistry, old data taken on 1980s were comparing with the recent groundwater chemistry data. The evaluation shows that nitrate content of groundwater in 1980s was a minor anion, but nowadays become a major anion, especially in the shallow groundwater in the centre of Yogyakarta City. This evidence shows that there is an evolution of groundwater chemistry in shallow groundwater below Yogyakarta City due to contamination from un-proper on-site sanitation system.
 
 Keywords: Urbanization, Yogyakarta city, rural dwellings, settlements, agglomeration, contamination, groundwater

Development of single‐step liquid chromatography methods with ultraviolet detection for the measurement of inorganic anions in marine waters

Although a number of techniques exist to measure the major and minor inorganic anions Cl‐, NO2‐, Br‐, NO3‐, or SO42‐ in marine waters and sediment porewaters, a single method that can quantify all five anions in a single step with a sufficiently low detection limit has yet to be developed. In this work, a novel ion‐chromatographic separation procedure was developed that exploits the UV‐absorbing properties of Br‐, NO3‐, and NO2‐, as well as the suppression of eluent absorbance by high concentrations of Cl‐ and SO42‐ to quantify all these anions simultaneously in marine waters. If additional sensitivity for the minor anions Br‐, NO3‐, and NO2‐ is needed, NaCl can be used as eluent in a matrix elimination method that no longer allows for Cl‐ and SO42‐ determination. These methods are isocratic, require no chemical or electronic suppression, are not subject to interferences, and can resolve the anions in less than 18 min. The decrease in analysis time and the number of analyses required compared with conventional methods lowers the costs associated with laboratory analysis of marine samples. Last, the simplicity and good limits of detection make this separation method suitable for in situ analyses of marine waters and porewaters, and an in situ liquid chromatograph is currently under development for these applications.

Geochemistry and modification of oilfield brines in surface pits in Northern Kuwait

Oilfield brines (produced water) are produced as a waste product daily at the gathering centers (GCs) in Kuwait oilfields. The geochemical evolution of the water produced at the GC (fresh brine) to stagnant pit water (evaporate) has been investigated in the northern fields of Kuwait, and a model is presented showing time-dependent variations. Kuwait oilfield brines are globally similar to others in other large sedimentary basins (USA, Canada), but modifications have occurred due to seawater injection practices performed episodically during the oil extraction process. Brine water chemistry changes from generally average brine chemistry (based on cations and anions) to saturated mixture of seawater, oilfield brine, and anthropogenic chemical pollutants. The objective of this study was to harmonize the database of brine waters in terms of regional identity by comparison with oilfield brines elsewhere, identify water–rock interaction, and statistically treat daily recordings from the pits in order to identify injection peaks and troughs. Laboratory analysis of major and minor cations and anions from the Rawdatayn samples gave the following concentration ranges in parts per million (ppm): (Na+, 11,698–203,977), (Ca2+, 2,216–98,514), (Mg2+, 1,602–28,885), (K+, 1,528–16,573), (Sr2+, 70–502), (Ba2+, 0.01–18.04), (Fe2+, 0.01–8.93), (Li+, 0.09–6.48), (Si2+, 0.00–13.18), (B3+, 0.05–37.45), (SO42+, 330–3100). For the Sabriyah oilfield samples, the major and minor cations and anions concentration ranges in ppm are: (Na+, 9,807–274,947), (Ca2+, 2,555–77,992), (Mg2+, 1,415–28,183), (K+, 764–19,201), (Sr2+, 77.84–641), (Ba2+, 0.15–6.76), (Fe2+, 0.016–38.88), (Li+, 0.05–6.83), (Si2+, 0.0195–16.84), (B3+, 7.17–55.33), (SO42+, 44,812–135,264). The stable isotopic analysis of five samples indicates normal trends in oxygen and hydrogen isotopes that classify the waters as “connate” which follow an evaporation trend. Carbon isotopic signatures are normal for hydrocarbon fields and average out around GC15, δ18O‰ = 1.4, δD‰ = −10, δ13C‰ = −3.6; while for GC23, δ18O‰ = 2.3, δD‰ = −4, δ13C‰ = −2.5; for GC25, δ18O‰ = −2.0, δD‰ = −14, δ13C‰ = −4.6; for pit1, δ18O‰ = 2.3, δD‰ = −5, δ13C‰ = −18.3; and for pit 2, δ18O‰ = 2.5, δD‰ = −4, δ13C‰ = −17.8. Carbon isotope average values for all brine samples from the GCs is = −56 which falls within normal hydrocarbon formation water category. Data spikes coincide with injection periods at the following times (A: May–Jun, 2006), (B: Sep–Oct, 2006), (C: Jan–Feb, 2007), (D: Mar, 2007), (E: May–Jun, 2007), (F: Feb, 2006), (G: Mar–Apr, 2006) and, subsequently the decay to “normal” brine occurs over a period of several weeks. The database was large enough to apply a principal component statistical analysis (PCA). PCA and geo-statistical techniques reveal several distinct population groups. The main chemical groups in the data are as follows: plateau, spike groups, and pit evaporation group. The spike periods correlate closely with seawater injection periods (Jan–Feb, Mar–Apr, May–Jun, and Sep–Oct). The pit chemistry reveals exceptionally high evaporation processes coinciding with summer peak temperature. PCA results show distinct groupings centered around the major elements reminiscent of other oilfields, but with the added evaporation trend strongly enhanced.

Sensitive determination of anions in saliva using capillary electrophoresis after transient isotachophoretic preconcentration

A transient isotachophoresis–capillary electrophoresis (tITP–CE) system for the determination of minor inorganic anions in saliva is described. The complete separation and quantification of bromide, iodide, nitrate, nitrite, and thiocyanate has been achieved with only centrifugation and dilution of the saliva sample. In-line tITP preconcentration conditions, created by introduction of the plugs of 5 mM dithionic acid (leading electrolyte) and 10 mM formic acid (terminating electrolyte) before and after the sample zone, respectively, allowed the limits of direct UV absorption detection (at 200 nm) to be up to 50-fold improved as compared with CE without tITP. As a result, nitrate and thiocyanate were still detectable at 4.6 and 3.8 μg l −1, respectively, in 1000 times diluted saliva. The daily variations of anionic concentrations in saliva samples taken from a smoking health volunteer were discussed based on the results of tITP–CE analysis. It was confirmed that the thiocyanate concentration in saliva noticeably increased after smoking. This is apparently the first report on simultaneous quantification of more than four anionic salivary constituents using CE.

Effects of plant food potassium salts (citrate, galacturonate or tartrate) on acid–base status and digestive fermentations in rats

Potassium (K) organic anion salts, such as potassium citrate or potassium malate in plant foods, may counteract low-grade metabolic acidosis induced by western diets, but little is known about the effect of other minor plant anions. Effects of K salts (chloride, citrate, galacturonate or tartrate) were thus studied on the mineral balance and digestive fermentations in groups of 6-week-old rats adapted to an acidogenic/5 % inulin diet. In all diet groups, substantial amounts of lactate and succinate were present in the caecum, besides SCFA. SCFA were poorly affected by K salts conditions. The KCl-supplemented diet elicited an accumulation of lactate in the caecum; whereas the lactate caecal pool was low in rats fed the potassium tartrate-supplemented (K TAR) diet. A fraction of tartrate (around 50 %) was recovered in urine of rats fed the K TAR diet. Potassium citrate and potassium galacturonate diets exerted a marked alkalinizing effect on urine pH and promoted a notable citraturia (around 0.5 micro mol/24 h). All the K organic anion salts counteracted Ca and Mg hyperexcretion in urine, especially potassium tartrate as to magnesuria. The present findings indicate that K salts of unabsorbed organic anions exert alkalinizing effects when metabolizable in the large intestine, even if K and finally available anions (likely SCFA) are not simultaneously bioavailable. Whether this observation is also relevant for a fraction of SCFA arising from dietary fibre breakdown (which represents the major organic anions absorbed in the digestive tract in man) deserves further investigation.

Monitoring of V(IV) and V(V) in Etnean drinking-water distribution systems by solid phase extraction and electrothermal atomic absorption spectrometry

Monitoring activities carried out since 1994 showed the presence of significant levels of vanadium in drinking waters delivered in a lot of Etnean towns. The highest vanadium concentration was found in ground waters collected in the drainage gallery Ciapparazzo located on the Northwestern flank of Mt. Etna in Bronte's area (Catania, Italy). This drainage gallery, with a flow rate of near 500 l s − 1 , is an important water source for several towns of the Etnean province. On account of different toxicological behaviours of V(IV) and V(V), which are the only possible oxidation states in aqueous media, a research project was set up to evaluate the ratio between their concentrations before and after disinfection treatments (chlorination or UV irradiation). Data were acquired in the most representative sites of the drainage gallery and the distribution network to evaluate the effect of residence times and disinfection treatments on possible species interconversion. The average total concentration of vanadium was 165 μg l − 1 . Speciation analyses performed by solid phase extraction of both species followed by furnace atomic absorption spectrometric determination of V(IV) eluates revealed that the latter was the predominant species (90–100%) in untreated waters. Moreover, among the two disinfecting treatments applied by the water supplier, only sodium hypochlorite altered the species ratio and determined an instant increase of near 20% in V(V) relative concentration. No significant effect was observed as residence time varied in the drainage gallery or in the distribution systems. Other physico-chemical and chemical parameters (i.e. pH, E H, water temperature, electrical conductance, dissolved oxygen as well as major and minor inorganic cations and anions) were determined in the collected water samples to evaluate if they are proper or not for interconversion of the two V species. Redox potential of the water was also correlated to the percentage of V(IV).

Complementary Stimulation of Hepatobiliary Transport and Detoxification Systems by Rifampicin and Ursodeoxycholic Acid in Humans

Rifampicin (RIFA) and ursodeoxycholic acid (UDCA) improve symptoms and biochemical markers of liver injury in cholestatic liver diseases by largely unknown mechanisms. We aimed to study the molecular mechanisms of action of these drugs in humans. Thirty otherwise healthy gallstone patients scheduled for cholestectomy were randomized to RIFA (600 mg/day for 1 week) or UDCA (1 g/day for 3 weeks) or no medication before surgery. Routine biochemistry, lipids, and surrogate markers for P450 activity (4beta-hydroxy cholesterol, 4beta-OH-C) and bile acid synthesis (7alpha-hydroxy-4-cholesten-3-one, C-4) were measured in serum. Bile acids were analyzed in serum, urine, and bile. A wedge liver biopsy specimen was taken to study expression of hepatobiliary ABC transporters as well as detoxification enzymes and regulatory transcription factors. RIFA enhanced bile acid detoxification as well as bilirubin conjugation and excretion as reflected by enhanced expression of CYP3A4, UGT1A1, and MRP2. These molecular effects were paralleled by decreased bilirubin and deoxycholic acid concentrations in serum and decreased lithocholic and deoxycholic acid concentrations in bile. UDCA on the other hand stimulated the expression of BSEP, MDR3, and MRP4. UDCA became the predominant bile acid after UDCA treatment and lowered the biliary cholesterol saturation index. RIFA enhances bile acid detoxification as well as bilirubin conjugation and export systems, whereas UDCA stimulates the expression of transporters for canalicular and basolateral bile acid export as well as the canalicular phospholipid flippase. These independent but complementary effects may justify a combination of both agents for the treatment of cholestatic liver diseases.

Biological activity of for-Met-Leu-Phe-OMe analogs: Relevant substitutions specifically trigger killing mechanisms in human neutrophils

Two analogs of the prototypical peptide for-Met-Leu-Phe-OMe (fMLP-OMe), for-Gln-Tyr-Phe-OMe ( 1) and for-Gln-Tyr-Tyr-OMe ( 2), carrying unusual hydrophilic residues, were synthesized in order to investigate whether they provoked specific biological responses, as well as intracellular calcium mobilization, in human neutrophils. Whereas neither compound stimulates chemotaxis, both are able to elicit lysosomal enzyme production. However compound 1 is able to trigger copious superoxide anion production while compound 2 only elicits minor superoxide anion production. In binding experiments on formylpeptide receptors, the newly synthesized compounds for-Gln-Tyr-Phe-OMe ( 1) and for-Gln-Tyr-Tyr-OMe ( 2) showed affinity values in the micromolar range. These derivatives demonstrate inability to find a positive contribute from single substitutions. A very important result of this research is the evidence of the ability of the formyl group alone to trigger the primary target of the human neutrophil activity, i.e. killing mechanisms, by activating the specific receptor conformation.

Positive and negative ion chemistry of the anesthetic halothane (1‐bromo‐1‐chloro‐2,2,2‐trifluoroethane) in air plasma at atmospheric pressure

The ion chemistry of 1-bromo-1-chloro-2,2,2-trifluoroethane (the common anesthetic halothane) in air plasma at atmospheric pressure was investigated by atmospheric pressure chemical ionization mass spectrometry (APCI-MS). The major positive ion observed at low declustering (API interface) energies is the ionized dimer, M(+.)M, an unexpectedly abundant species which possibly is stabilized by two H-bonding interactions. At higher energies [M--HF](+.) and [M--Br](+) prevail; the former, corresponding to ionized olefin [ClBrC=CF(2)](+.), appears to originate from M(+.)M and is quite stable towards fragmentation. The latter fragment ion ([M--Br](+)) and its analogue, [M--Cl](+), which is also observed though at much lower abundance, are originally ethyl cations (+)CHX--CF(3) (X = Br, Cl) which, upon collisional activation, rearrange and fragment to CHFX(+) via elimination of CF(2). All of the above described ions are also observed in humid air: in addition, the oxygenated ion [ClBrC=CFOH](+.) also forms in humid air via water addition to [ClBrC=CF(2)](+.) and HF elimination, as observed earlier for ionized trichloroethene. In contrast with similar chloro- and fluoro-substituted ethanes, halothane does not react with H(3)O(+) in the APCI plasma, a result confirmed by selected ion APCI triple-quadrupole (TQ) experiments. Major negative ions formed from halothane in the air plasma are Br(-) and, to a lesser extent, Cl(-), and their complexes with neutral halothane. APCI-TQ experiments indicated that Br(-) and Cl(-) are formed via reaction of halothane with O(2) (-.), O(2) (-.)(H(2)O) and O(3) (-.), possibly via dissociative electron transfer or nucleophilic substitution. Competing proton transfer was also observed in the reaction with O(2) (-.) and, at high halothane pressure, also with O(2) (-.)(H(2)O); at lower pressures the molecular anion M(-.) was observed instead. The other minor anions of the air plasma, NO(2) (-), N(2)O(2) (-.) and NO(3) (-), were found to be unreactive towards halothane.

Geochemistry of the Gavkhoni Playa Lake Brine

The Gavkhoni Playa Lake is located to the southeast of Esfahan, Iran. It is surrounded by the Varzaneh aeolian sand field to the west and alluvial/fluvial sediments to all other directions. It is typical of the few permanent lakes within closed drainage basins in Iran. The properties of intermittent fine-grained and coarse-grained siliciclastic and finally fine-grained evaporite sediments suggest that the basin was influenced repeatedly by wet and dry periods. During periods of flooding, it had been a shallow permanent lake. With increasing aridity, the middle of the lake became increasing restricted and shallower which resulted in the formation of a salt pan, contributing to the nature of the lake brine. Due to the enclosed nature of the lake system, the water chemistry of Gavkhoni Playa Lake is dominated by sodium and chloride ions but shows wide variations in composition and concentration through time and location. The percentage of Na+ (1,012 to 10,3040 ppm), Cl− (4,118 to 19,9365 ppm), Mg2+ (360 to 25,691 ppm), and K+ (78 to 3,570 ppm) is highest toward the south and at a minimum in the north. Calcium content, ranging from 160 to 3,480 ppm, appears highest in the north. The percentage of strontium (5 to 292 ppm) with the highest value to the north, is extremely low in comparison to other elements. Sulfate is another abundant anion in the brines with the highest content of 22,051 ppm. Bicarbonate is a minor anion ranging from 73 to 450 ppm with the highest values to the north and west. The concentration of sulfate and bicarbonate does not change regularly in the brines from north to south, nor does it vary seasonally. The chemical analysis of the brine shows that it becomes progressively depleted in carbonate and sulfates from the margins to the center of the lake. It ultimately became a Na+, (Mg2+), Cl− brine type in the northern section and a Na+, Mg2+, Cl−brine type in the central part of the lake. After complete desiccation, the mineral assemblage exhibited halite, carnallite, bischofite, and tachyhydrite in abundance.

Molecular assembly in secondary minerals - Raman spectroscopy of the arthurite group species arthurite and whitmoreite

Two members of the arthurite mineral group, arthurite and whitmoreite A(Fe3+) 2 (XO 4 ) 2 (O,OH) 2 .4(H 2 O) where A = Cu(II), Zn(II), Pb(II) or Fe(II) and X = As, P, S have been studied using Raman spectroscopy. The minerals are based upon the combination of a divalent cation such as Cu(II), Zn(II), Pb(II) or Fe(II) and the trivalent cation, Fe(III), with counterbalancing of hydroxyl, arsenate, phosphate and sulphate anions. Such minerals lend themselves to analysis by Raman spectroscopy. For arthurite Cu(Fe 3 + ) 2 (AsO 4 ,PO 4 ,SO 4 ) 2 (O,OH) 2 .4(H 2 O), arsenate and hydroxyl anions are observed as well as minor phosphate and significant carbonate anions. For whitmoreite FeFe 2 (PO 4 ) 2 (OH) 2 .4(H 2 O), hydroxyls and phosphate are the major anions with significant sulphate and some carbonate. Raman spectroscopic analysis of two whitmoreite samples from the same mineral field suggests that differentiation by concentration of the anions occurs in the molecular assembly of the anions as crystallisation occurs as a function of the equilibrium conditions. Changing solution conditions are reflected in the varying compositions in the lattice.

Functional and Chemical Calibrates of Ceramic Cup Water Samplers in Forest Soils

A study was conducted to assess the properties of a tension porous-ceramic cup soil-solution sampler and its usefulness in extracting soil solutions in selected forest soils (haplic Umbrisols) at “Sierra De Gata” Mountains, CW-Spain. The main characteristics of the sampler evaluated were hydraulic conductivity, the time required to obtain the soil-water sample, and the volume of water uptake for optimum calibration prior to analysis of the chemical composition of the soil water solution. Hydraulic conductivity values were not substantially modified during the sampling (two hydrologic cycles). The time required to obtain the samples was relatively short (mean value 2 h) and the sphere of sampling influence was small (radii ranging from 6 to 15 cm), both depending on the size of the sampler. The chemical analyses obtained after calibrating the ceramic cup sampler pointed to: a) an effect of light adsorption by the ceramic cup, involving DOC, major and minor cations (Na+, K+, Ca2+, Mg2+, Fe3+, Al3+, Mn2+, and Zn2+), and and anions; b) a release of H4SiO4; and c) no clear trend for Cl−. The Cu2+ values obtained between a blank soil solution and those obtained after passage through the ceramic cup were not correlated. Relatively low pH values (the pH of these acid forest soils is 5.1–6.2) favor the adsorption of anions and DOC, the latter also increasing the exchange capacity and cation adsorption of the cup. The results point to a generalized tendency of the ceramic cup to adsorb DOC, cations and anions (with the exception of chlorides), H4SiO4, by contrast, being released.