Determining conventional and unconventional oil and gas well brines in natural samples III: mass ratio analyses using both anions and cations

Identifying the types of contamination and their sources in surface and groundwater is fundamental for effective protection of private and public source waters. Here we employed mass ratio analyses of a variety of anion and cation pairs to characterize flowback, produced water, and mine drainage. These endmembers were used to evaluate the source contributions of natural surface and ground water samples. A total of 1,177 ground water and surface water samples were analyzed including high-quality source waters and waters suspected of being impacted by drilling and mining activity. We found the following chemical ratios resolved different sources of contamination: Mg/Na vs SO₄/Cl; SO₄/Cl vs Mg/Li; Br/SO₄ vs Ba/Cl; and Br vs Mg/Li. While no single parameter or mass ratio pairing by itself was definitive it was possible to converge on a likely source of contamination using multiple lines of analytical evidence. Further, this process clarified sources in impacted samples where one or more parameters commonly considered diagnostic of specific sources (e.g., Br, Ba), were below detection limits (e.g., too dilute) or not tested for. Ultimately, movement of sample values within the mass ratio space allows tracking of changes in water quality and contamination source dynamics as the water chemistry evolves.

Determining conventional and unconventional oil and gas well brines in natural sample II: Cation analyses with ICP-MS and ICP-OES

Flowback and produced water generated by the hydraulic fracturing of unconventional oil and gas plays contain a suite of cations (e.g., metals) typically in a high salt (e.g., NaCl) matrix. Here, we analyzed the chemical (cation) composition of production fluids associated with natural gas and oil development (e.g., flowback, produced water, impoundment fluids), along with mine drainage, and surface and ground water samples using ICP-OES and ICP-MS. ICP-MS and ICP-OES analytical performance and interference effects were evaluated. Both platforms exhibited excellent analytical spike recoveries, detection limits for blank and spiked solutions, and accuracy for standard certified reference materials. Mass ratio analyses using Ca/Sr, Ca/Mg, Ba/Sr, Mg/Sr, and B and Li, were assessed for their efficacy in differentiation among brines from conventional oil wells, produced water from unconventional oil and gas wells and impoundments, mine drainage treatment pond water, groundwater, and surface water. Examination of Mg/Sr ratios when compared with Li concentrations provide clear separation among the different types of samples, while Ca/Mg versus Ca/Sr correlations were useful for distinguishing between conventional and unconventional oil and gas fluids.

An umbelliferone-derivated fluorescent sensor for selective detection of palladium(II) from palladium(0) in living cells

Palladium (Pd) has drawn worldwide attentions because its connections to industry, chemistry, biological material and public health. Quantitative and selective detection tools for Pd and its ion forms are in urgent necessity. Here an umbelliferone derivative Umb-Pd2 was provided as a small, steady, safe and selective sensor for detecting Pd(II). It indicated advantages including sensitive (LOD 1.1 nM), wide pH tolerance (5.0-10.0), applicable linear range (0-1.8 equivalent) and low toxicity. The most attractive point was its explicit selectivity towards Pd(II) from Pd(0) in both independent and coexistence systems. This distinguishing ability was further utilized in imaging in living cells, raising this work as a rare and important example among all the published papers on palladium sensing. Thus, Umb-Pd2 supplied a potential approach for further improvement and applications in both daily chemistry and public health.

A novel fluorescent chemosensor for detection of Zn(II) ions based on dansyl-appended dipeptide in two different living cells

This paper describes a new fluorescent chemosensor (DSH) based on dipeptide conjugated with dansyl group, which was synthesized by solid phase peptide synthesis (SPPS) technology. DSH exhibited a highly selective and sensitive toward Zn²⁺ ions by "turn-on" response based on generation of monomer-excimer mechanism in aqueous solutions, and the detection limit was calculated at 11.2 nM. In addition, the reversible of DSH-Zn with Na₂EDTA establishes the reuse of DSH, and the circulation effect was very good. Moreover, DSH had good water solubility, and was successfully applied to bioimage intracellular Zn²⁺ ions and Na₂EDTA in two different living cells with exciting cellular permeability and low cytotoxicity, which indicated that DSH had great potential in the application of biological imaging.

Rhodamine-azobenzene based single molecular probe for multiple ions sensing: Cu2+, Al3+, Cr3+ and its imaging in human lymphocyte cells

A photoinduced electron transfer (PET) and chelation-enhanced fluorescence (CHEF) regulated rhodamine-azobenzene chemosensor (L) was synthesized for chemoselective detection of Al³⁺, Cr³⁺, and Cu²⁺ by UV-Visible absorption study whereas Al³⁺ and Cr³⁺ by fluorimetric study in EtOH-H₂O solvent. L showed a clear fluorescence emission enhancement of 21 and 16 fold upon addition of Al³⁺ and Cr³⁺ due to the 1:1 host-guest complexation, respectively. This is first report on rhodamine-azobenzene based Cr³⁺ chemosensor. The complex formation, restricted imine isomerization, inhibition of PET (photo-induced electron transfer) process with the concomitant opening of the spirolactam ring induced a turn-on fluorescence response. The higher binding constants 6.7 × 10³ M^-1 and 3.8 × 10³ M^-1 for Al³⁺ and Cr³⁺, respectively and lower detection limits 1 × 10^-6 M and 2 × 10^-6 M for Al³⁺ and Cr³⁺, respectively in a buffered solution with high reversible nature describes the potential of L as an effective tool for detecting Al³⁺ and Cr³⁺ in a biological system with higher intracellular resolution. Finally, L was used to map the intracellular concentration of Al³⁺ and Cr³⁺ in human lymphocyte cells (HLCs) at physiological pH very effectively. Altogether, our findings will pave the way for designing new chemosensors for multiple analytes and those chemosensors will be effective for cell imaging study.

Novel polysiloxane-based rhodamine B fluorescent probe for selectively detection of Al3+ and its application in living-cell and zebrafish imaging

Polysiloxanes have excellent stability and biological relevance and are suitable for biological research. However, there were few polysiloxane-based fluorescent probes for bioimaging. This report successfully designed a new polysiloxane-based polymer fluorescent probe (RB-1) for the first time as a "turn-on" fluorescent probe response to Al³⁺ ion with highly sensitive and selectivity. Importantly, this probe could also apply both in cell and zebrafish imaging, indicating the huge application development prospects of polysiloxane-based fluorescent probes in future.

Hydrochemical assessment of surface and ground waters used for drinking and irrigation in Kardeh Dam Basin (NE Iran)

Water quality for drinking and irrigation usage was examined in Kardeh dam basin in NE Iran. Thirty-two surface and groundwater samples were collected and analyzed for major ions of Ca²⁺, Mg²⁺, Na⁺, K⁺, HCO₃^-, CO₃^2-, SO₄^2- and Cl^- by using standard analytical methods of titration and atomic absorption spectrophotometry at geochemistry laboratory of Ferdowsi University of Mashhad. Dominant cation in most of the water samples are Ca²⁺ and Mg²⁺, and dominant anion is HCO₃^-. Water quality index (WQI) was calculated based on physicochemical parameters such as pH, EC and major ions. The WQI values were less than 100 (maximum permissible value) for all samples and suitable for drinking usage; nevertheless, water quality decreased from northwest toward the southeast of studied area. Also, based on modified NSFWQI, the water resources were classified into average and good categories, which are suitable for irrigation uses. More than 40% of the samples are not suitable for irrigation uses based on magnesium hazard values. Carbonate rocks have the main effect on hydrogeochemical facies and the water quality in studied area. According to drinking and irrigation indices, water quality is reducing from upstream toward downstream to the southeast of the basin.

Are soils beneath coniferous tree stands more acidic than soils beneath deciduous tree stands?

In 2008, the Mulberry River, a National Wild and Scenic River, was listed as impaired due to low pH (below pH 6.0). Over the last 50 years, the volume of conifers in the Ozark region has increased 115% since 1978 which may result in the acidification of nearby aquatic ecosystems. The objective of this study was to determine if differences exist in soil and litter chemical properties between deciduous and coniferous tree stands. Aboveground litter (n = 200) and soil (n = 400) at 0- to 5- and 5- to 15-cm depths were collected at paired deciduous and coniferous stands at 10 locations within the Mulberry River watershed and analyzed for a suite of chemical parameters. There were no differences (P > 0.05) in several measures of soil acidity between deciduous and coniferous stands. Litter collected from the coniferous stands was more acidic than deciduous litter (4.4 vs 4.7; P < 0.05). Cation exchange capacity, exchangeable Ca and Mg, and water-soluble P and Mg contents differed (P < 0.05) by stand and depth. Cation exchange capacity and exchangeable Ca and Mg were greatest in the 0- to 5-cm depth interval of the coniferous stands. Water-soluble P and Mg contents were greatest within the 0- to 5-cm depth interval which did not differ (P > 0.05) between stand but were greater than the 5- to 15-cm depth interval. Although limited to the top 15-cm of soil, the similarity in soil acidity between stands suggests that conifer growth may not be a substantial source of acidity to the Mulberry River.

Identification and characterization of multifunctional cationic peptides from traditional Japanese fermented soybean Natto extracts

In this study, we investigated the lipopolysaccharide (LPS)-neutralizing and angiogenic activities of cationic peptides derived from the traditional Japanese fermented product Natto, which is made by fermenting cooked soybeans using Bacillus subtilis. Initially, we prepared 20 fractions of Natto extracts with various isoelectric points (pI's) using ampholyte-free isoelectric focusing (autofocusing). Cationic peptides were then purified from fractions 19 and 20, whose pH values were greater than 12, using reversed-phase high-performance liquid chromatography, and were identified using matrix-assisted laser/desorption ionization-time-of-flight mass spectroscopy. Among the 13 identified cationic peptides, seven (KFNKYGR, FPFPRPPHQK, GQSSRPQDRHQK, QRFDQRSPQ, ERQFPFPRPPHQK, GEIPRPRPRPQHPE, and EQPRPIPFPRPQPR) had pI's greater than 9.5, positive net charges, and differing molecular weights. These peptides were then chemically synthesized and applied to chromogenic LPS-neutralizing assays using Limulus amebocyte lysates, and 50% effective (neutralizing) concentrations of 2.6-5.5 μM were demonstrated. In addition, tube formation assays in human umbilical vein endothelial cells revealed angiogenic activities for all but one (GEIPRPRPRPQHPE) of these seven cationic peptides, with increases in relative tube lengths of 23-31% in the presence of peptides at 10 μM. Subsequent experiments showed negligible hemolytic activity of these peptides at concentrations of up to 500 μM in mammalian red blood cells. Collectively, these data demonstrate that six cationic peptides from Natto extracts, with the exception of GEIPRPRPRPQHPE, have LPS-neutralizing and angiogenic activities but do not induce hemolysis.

Contribution of tobacco composition compounds to characteristic aroma of Chinese faint-scent cigarettes through chromatography analysis and partial least squares regression

To further explore the aroma mechanism of Chinese faint-scent cigarettes, the contribution of tobacco leaf composition, including six kinds of saccharides, eight tobacco alkaloids, seventeen kinds of organic acids, eighteen kinds of amino acids and four ions (Na+, K+, Mg2+ and Ca2+), on aroma quality characteristic (freshness, flowery and acidic notes) of faint-scent cigarettes was analyzed by chromatography and PLSR. The results showed that (i) xylose, fructose, glucose, maltose and sucrose were negatively correlated to acidic note, while galactose showed significantly positive correlation to acidic note. (ii) Phenylalanine and proline showed significant and positive correlation with characteristic aromas. Proline contributed to freshness and flowery, while leucine significantly contributed to acidic note. (iii) Most organic acids were significantly correlated to characteristic aromas. Palmitic acid and stearic acid contributed to the freshness, while dodecanoic acid and palmitic acid significantly contributed to flowery. (iv) Tobacco Na ion plays negative and significant correlation to acidic note.

A high performance 2-hydroxynaphthalene Schiff base fluorescent chemosensor for Al3+ and its applications in imaging of living cells and zebrafish in vivo

Developing high performance fluorescent chemo-sensors for in vitro and in vivo Al³⁺ detection is highly desirable, because Al³⁺ accumulation has been involved to various diseases. Herein, we report a highly selective and sensitive Schiff base fluorescent probe, H₃L, based on 2-hydroxynaphthalene, which can recognize aluminum ions and exhibit an "off-on" mode with high selectivity in methanol solutions. The detection limit of the probe for Al³⁺ is as low as 10^-7 M which was determined by fluorescent titration. The high selectivity and high sensitivity of H₃L for Al³⁺ are attributed to the inhibition of ESIPT. Additionally, the distribution of intracellular Al³⁺ ions could be observed under confocal fluorescence microscopy. Moreover, we also applied H₃L for in vivo detection of Al³⁺ ions in living zebrafish larvae.

Geochemistry and quality of groundwater of the Yarmouk basin aquifer, north Jordan

Quality of groundwater in the Yarmouk basin, Jordan has been assessed through the study of hydrogeochemical characteristics and the water chemistry as it is considered the main source for drinking and agriculture activities in the region. The results of the relationship between Ca²⁺ + Mg²⁺ versus HCO₃^- + CO₃^2-, Ca²⁺ + Mg²⁺ versus total cations, Na⁺ + K⁺ versus total cations, Cl^- + SO₄^2- versus Na⁺ + K⁺, Na⁺ versus Cl^-, Na⁺ versus HCO₃^- + CO₃^2-, Na⁺ versus Ca²⁺, and Na⁺: Cl^- versus EC describe the mineral dissolution mechanism through the strong relationship between water with rocks in alkaline conditions with the release of Ca²⁺, Mg²⁺, Na⁺, K⁺, HCO₃^-, CO₃^2-, SO₄^2-, and F^- ions in the groundwater for enrichment. Furthermore, evaporation processes, groundwater depletion, and ion exchange contribute to the increased concentration of Na⁺ and Cl^- ions in groundwater. Anthropogenic sources are one of the main reasons for contamination of groundwater in the study area and for increasing the concentration of Mg²⁺, Na⁺, Cl^-, SO₄^2-, and NO₃^- ions. Results show the quality of groundwater in the study area is categorized as follows: HCO₃^- + CO₃^2- > Cl^- > SO₄^2- > NO₃^- > F^- and Na⁺ > Ca²⁺ > Mg²⁺ > K⁺. In conclusion, the results of TDS, TH, and chemical composition showed that 26% of the groundwater samples were unsuitable for drinking. About 28% of groundwater samples in the study area have a high concentration of Mg²⁺, Na⁺, and NO₃^- above the acceptable limit. Also, based on high SAR, 10% of the groundwater samples were not suitable for irrigation purposes.

Chemical composition of rainwater in the Sinos River Basin, Southern Brazil: a source apportionment study

This study aimed to assess the chemical composition of the rainwater in three areas of different environmental impact gradients in Southern Brazil using the receptor model EPA Positive Matrix Factorization (EPA PMF 5.0). The samples were collected in a bulk sampler, from October 2012 to August 2014, in three sampling sites along with the Sinos River Basin: Caraá, Taquara, and Campo Bom. The major ions NH₄⁺, Na⁺, K⁺, Ca²⁺, Mg²⁺, F^-, Cl^-, NO₃^-, SO₄^2-, and pH were analyzed, as well as identify the main emission sources. The most abundant cations and anions were Ca²⁺, Na⁺, Cl^-, and SO₄^2-, respectively. The mean pH value in the Sinos River Basin during the study period was 6.07 ± 0.49 (5.13-7.05), which suggests inputs of alkaline species into the atmosphere. The most important neutralizing agents of sulfuric and nitric acids in the Sinos River Basin are Ca²⁺ (NF = 1.36) and NH₄⁺ (NF = 0.57). The source apportionment provided by the EPA PMF 5.0 resulted in four factors, which demonstrate the influence of anthropogenic and natural sources, in the form of (a) industry/combustion of fossil fuels (F^- and SO₄^2-), (b) marine contribution (Na⁺ and Cl^-), (c) crustal contribution (K⁺, Ca²⁺, and NO₃^-), and (d) agriculture/livestock (NH₄⁺). Therefore, this study allows a more appropriate understanding of factors that contribute to rainwater chemical composition and also to possible changes in air quality.

Migration and leaching characteristics of base cation: indicating environmental effects on soil alkalinity in a karst area

In karst areas, rock dissolution often results in the development of underground networks, which act as subterranean pathways for rapid water and nutrient (and possibly soil) loss during precipitation events. Loss of soluble nutrients degrades surface soils and decreases net primary productivity, so it is important to establish flow pathways and quantify nutrient loss during rainfall events of different magnitudes. We conducted a simulated rainfall experiment in karst and nonkarst areas to compare the concentration of nutrients in surface and subsurface flow water and effects on soil alkalinity in three lithologic soil formations under five different rainfall intensity treatments. Compared with the nonkarst area, the runoff in subsurface flows and the proportion of nutrient loss in the subsurface flow are larger in the karst area and less affected by rain intensity. The maximum loss loads of calcium (Ca²⁺) and magnesium (Mg²⁺) ions were 32.9 and 19.8 kg ha^-1, respectively. With the estimate of base cation loss loads in the China southern karst area under the rainfall intensity of 45 mm h^-1, more than 80% of the base cation loss load occurred in the limestone karst area. Although the alkalinity leaching value in nonkarst was similar to that in the karst area under simulated rainfall conditions, its impact on the ecological environment was quite different.

Synthesis of a magnetic polystyrene-based cation-exchange resin and its utilization for the efficient removal of cadmium (II)

A magnetic cation-exchange resin (MCER) was prepared by copolymerization of oleic acid-grafted magnetite with styrene, divinylbenzene (DVB), and triallylisocyanurate (TAIC) for removing Cd(II) from wastewater. A non-magnetic cation-exchange polystyrene resin (CEPR) was also prepared as a reference. Structural and morphological analyses revealed that the MCER and CEPR were mesoporous microspheres; the MCER contained about 25% Fe₃O₄. The influence of temperature, pH, contact time, and the initial concentration of Cd(II) on the adsorption of Cd(II) was investigated. The maximum adsorption capacity of the MCER reached 88.56 mg/g, which was achieved at 343 K using a Cd(II) initial concentration of 200 mg/L. The adsorption processes attained equilibrium within 120 min for the MCER and 300 min for the CEPR, and were well described by a pseudo-second-order kinetic model. Furthermore, the equilibrium adsorption data fitted the Freundlich isotherm model better than the Langmuir model. The superior magnetic response and regeneration of the MCER make it a good candidate as an adsorbent for removing Cd(II) from wastewater.

Hydrogeochemistry study and groundwater quality assessment in the north of Isfahan, Iran

This study presents the groundwater quality assessment in the north of Isfahan, Iran. In the study area, assessment and measurement of groundwater hydrochemical parameters such as pH, total dissolved solids (TDS), electrical conductivity (EC), sodium absorption ratio (SAR), total hardness, major cations (K⁺, Na⁺, Ca²⁺ and Mg²⁺) and major anions (Cl^-, [Formula: see text] and [Formula: see text]) concentrations were performed. Accordingly, the 66 water samples from different locations were collected during April and May 2015. Water samples collected in the field were analyzed in the laboratory for cations and anions using the standard methods. In this research, the analytical results of physiochemical parameters of groundwater were compared with the standard guideline values as recommended by the world health organization (WHO) for drinking and public health purposes. The pH values of groundwater samples varied from 7.05 to 8.95 with a mean of 7.78, indicating a neutral to slightly alkaline water. TDS values showed that 14% of the samples exceeds the desirable limit given by WHO. EC values varied from 213 to 4320 µS/cm, while 23% of the samples were more than the standard limit. Gibbs diagram had shown that 90% of the samples in the study area fall in the rock weathering zone, and this means that chemical weathering of rock-forming minerals is the main factor controlling the water chemistry in the study area. Irrigation suitability and risk assessment of groundwater are evaluated by measuring EC, %Na, SAR and RSC. According to the dominant cations and anions, five types of water were identified in the water samples: Ca-HCO₃, Ca-SO₄, Na-Cl, Na-HCO₃ and Na-SO₄. The results show that the majority of samples (30 samples, 45%) belongs to the mixed Na-SO₄ water type. Correlation analysis and principal component analysis was used to identify the relationship between ions and physicochemical parameters. Results indicated that 18 stations of the study area had the best quality and can be used for irrigation and drinking purposes in the future.

Identification of number and type of cations in water-soluble Cs+ and Na+ calix[4]arene-bis-crown-6 complexes by using ESI-TOF-MS

The treatment of cesium-contaminated wastewater has become one of the biggest issues. The selective Cs⁺ removal from wastewater containing competitive alkali metal ions such as Na⁺ is desired to reduce the volume of sludge. Therefore, the present work focused on water-soluble calix[4]arene-bis-crown-6 (W-BisC6) to selectively capture Cs⁺. For characterization of the complex, UV-vis spectroscopy is commonly used, however, due to the limited availability of information it can be hard to quickly identify the specific structures of some complexes. In this work, the electrospray ionization time of flight spectrometry (ESI-TOF-MS) is successfully utilized to identify the number and type of cations in W-BisC6-cation complexes. ESI-TOF-MS accurately recognized 4 types of complex (W-BisC6-Na⁺, W-BisC6-Cs⁺, W-BisC6-2Na⁺, W-BisC6-Na⁺-Cs⁺), and the experimental and simulated results were almost perfectly matched. It also revealed the difficulty of W-BisC6-2Cs⁺ complex formation under the present conditions. Thus, this technique is significantly helpful for rapid identification of the specific structures of complexes during Cs⁺-contaminated wastewater treatment.

Enhancing peat metal sorption and settling characteristics

Peat is an excellent material for metal sorption since it naturally contains different kinds of functional groups that can sorb metal cations from water. The main objective of this work was to test low-cost treatment (acid and alkali) methods for natural peat, which would improve the settling properties of peat particles while maintaining its metal removal efficiency. Particularly, the poor settling properties of peat hinder its practical application. The study revealed that NaOH-treated peat (0.1M) had excellent settling properties and could be applied in wastewater applications having mixing and settling systems without a settling aid. The superior leaching of humic and fulvic acids in alkaline treatment caused a change in morphology, making it a harder and sticky material. Moreover, the NaOH-treated (0.1M) peat was proven to be the most efficient material for nickel removal followed by the HCl-treated (0.2M) peat, citric acid-treated (0.16M) peat and water-treated peat. A higher temperature and longer time slightly increased the Ni removal efficiency with NaOH-treated peat material. The settling of HCl-treated peat was studied further using polyacrylamide flocculants (cationic, neutral, anionic). Cationic flocculants performed best and the cationic charge density also had an effect on the flocculation performance of peat particles. This study provides further evidence that peat can be applied in the treatment of metal-containing wastewaters.

Considerations and Some Practical Solutions to Overcome Nanoparticle Interference with LAL Assays and to Avoid Endotoxin Contamination in Nanoformulations

Monitoring endotoxin contamination in drugs and medical devices is required to avoid pyrogenic response and septic shock in patients receiving these products. Endotoxin contamination of engineered nanomaterials and nanotechnology-based medical products represents a significant translational hurdle. Nanoparticles often interfere with an in vitro Limulus Amebocyte Lysate (LAL) assay commonly used in the pharmaceutical industry for the detection and quantification of endotoxin. Such interference challenges the preclinical development of nanotechnology-formulated drugs and medical devices containing engineered nanomaterials. Protocols for analysis of nanoparticles using LAL assays have been reported before. Here, we discuss considerations for selecting an LAL format and describe a few experimental approaches for overcoming nanoparticle interference with the LAL assays to obtain more accurate estimation of endotoxin contamination in nanotechnology-based products. The discussed approaches do not solve all types of nanoparticle interference with the LAL assays but could be used as a starting point to address the problem. This chapter also describes approaches to prevent endotoxin contamination in nanotechnology-formulated products.

Chemical characteristics and source analysis on ionic composition of rainwater collected in the Carpathians "Cold Pole," Ciuc basin, Eastern Carpathians, Romania

A study of precipitation chemistry was conducted for 11 years (01 January 2006-31 December 2016) in the Ciuc basin, Eastern Carpathians, Romania. The studied area is an enclosed basin, also called "the Carpathians cold pole." All collected samples were analyzed for major cations and anions. HCO₃^- concentrations were calculated based on the empirical relationship between pH and HCO₃^-. The multiannual arithmetic mean of pH values was found to be 6.57. The lowest and highest pH values were measured in 2009 and 2013, being 6.57% lower, respectively, 7.57% higher than the multiannual mean. Only 3.31% of the studied rainwater samples indicate acidic character. In descending order, the majority of the samples are as follows: NH₄⁺ >Ca²⁺ >SO₄^2- >Cl^- >HCO₃^- >NO₃^- >Na⁺ >K⁺ >Mg²⁺ >NO₂^- >H⁺. Principal component analysis (PCA) showed the NH₄⁺, Ca²⁺, and Mg²⁺ contribution to the neutralization process and their sources. The anthropogenic origin of SO₄^2- was supported by the high non-sea-salt fraction (NSSF) (~ 91%). The results of this study suggest that rainwater chemistry is strongly influenced by local natural and anthropogenic sources (agricultural activities) rather than marine sources. The pollutants in rainwater samples were mainly derived from calcareous and dolomitic soil dust and specific local climatic conditions, long-range transport, local industry, and traffic sources.

Spectrophotometric determination of anionic surfactants: optimization by response surface methodology and application to Algiers bay wastewater

A simple analytical method for quantitative determination of an anionic surfactant in aqueous solutions without liquid-liquid extraction is described. The method is based on the formation of a green-colored ion associate between sodium dodecylbenzenesulfonate (SDBS) and cationic dye, Brilliant Green (BG) in acidic medium. Spectral changes of the dye by addition of SDBS are studied by visible spectrophotometry at maximum wave length of 627 nm. The interactions and micellar properties of SDBS and cationic dye are also investigated using surface tension method. The pH, the molar ratio ([BG]/[SDBS]), and the shaking time of the solutions are considered as the main parameters which affect the formation of the ion pair. Determination of AS in distilled water gives a significant detection limit up to 3 × 10^-6 M. The response surface methodology (RSM) is applied to study the absorbance. A Box-Behnken is a model designed to the establishment of responses given by parameters with great probability. This model is set up by using the three main parameters at three levels. Analysis of variance shows that only two parameters affect the absorbance of the ion pair. The statistical results obtained are interesting and give us real possibility to reach optimum conditions for the formation of the ion pair. As the proposed method is free from interferences from major constituents of water, it has been successfully applied to the determination of anionic surfactant contents in wastewaters samples collected from Algiers bay.

Chemical characteristics of soluble aerosols over the central Himalayas: insights into spatiotemporal variations and sources

In order to investigate the spatial and temporal variations of aerosols and its soluble chemical compositions of the data gap zone in the central Himalayan region, aerosol samples were collected at four sites. The sampling location were characterized by four different categories, such as urban (Bode), semi-urban site in the northern Indo-Gangetic Plain (Lumbini), rural (Dhunche), and semiarid rural (Jomsom). A total of 230 aerosol samples were collected from four representative sites for a yearlong period and analyzed for water-soluble inorganic ions (WSIIs). The annual average aerosol mass concentration followed the sequence as Bode (238.24 ± 162.24 μg/m³)> Lumbini (161.14 ± 105.95 μg/m³)> Dhunche (112.40 ± 40.30 μg/m³)> Jomsom (78.85 ± 34.28 μg/m³), suggesting heavier particulate pollution in the urban and semi-urban sites. The total soluble ions contributed to 12.61-28.19% of TSP aerosol mass. The results revealed that SO₄^2- and NO₃^- were the major anion and Ca²⁺ and NH₄⁺ were the major cation influencing the aerosol composition over the central Himalayas. Calcium played a major role in neutralizing aerosol acidity followed by NH₄⁺ at all the sites. The major compound of aerosol was (NH₄)₂SO₄ and NH₄HSO₄ in the central Himalayas. Clear seasonality was observed at three observation sites, with higher concentrations during non-monsoon (dry periods) and lower during monsoon (wet period), suggesting washing out of aerosol particles by heavy precipitation during monsoon. In contrast, semiarid sites did not show the clear seasonal trend due to limited precipitation. Stationary sources were predominant over the mobile sources mostly in the remote sites. Principal component analysis confirmed that the major sources of WSIIs in the region were industrial emissions, fossil fuel and biomass burning, and crustal fugitive dusts. Nevertheless, transboundary aerosol transport over the region from polluted cities from south Asia could not be ignored as indicated by the clusters of air mass backward trajectory analysis.

Ions in Wine and Their Relation to Electrical Conductivity Under Ultrasound Irradiation

Change in electrical conductivity is considered a potential indicator for the on-line monitoring of wine aging accelerated by ultrasound, as determined in our previous study; however, the exact mechanism of change is currently unclear. In this study, the ion content and the total ionic strength were analyzed by ion-exchange chromatography to investigate the change mechanism of the electrical conductivity of wine under ultrasound irradiation. The results indicate that the changes in wine electrical conductivity during ultrasound treatment correlate with the changes in the cations (Na+, K+, Ca2+, Mg2+, and NH4+) and in the anions from the organic acids (malic acid, citric acid, tartaric acid, oxalic acid, and formic acid) and inorganic acids (Cl-, SO42-, and PO43-), especially for the ionic strength of the wine. Overall, electrical conductivity may be used to reflect the chemical reactions related to wine aging to a certain extent because the reactions can be initiated by the conversion of cations and by the degradation or auxiliary function of organic acids.

Dendrochemical evidence for soil recovery from acidic deposition in forests of the northeastern U.S. with comparisons to the southeastern U.S. and Russia

A soil resampling approach has detected an early stage of recovery in the cation chemistry of spruce forest soil due to reductions in acid deposition. That approach is limited by the lack of soil data and archived soil samples prior to major increases in acid deposition during the latter half of the 20th century. An alternative approach is the dendrochemical analysis of dated wood to detect temporal changes in base cations back into the 19th century. To infer environmental change from dendrochemical patterns of essential base cations, internal factors that affect cation chemistry such as the maturation of sapwood and the spread of wood infection need to be recognized. Potassium concentration was a useful marker of these internal maturation and infection that could affect the concentration of essential base cations in wood. Dendrochemical patterns in samples of red spruce in the eastern United States and Norway spruce in northwestern Russia were used to determine how internal changes in base cations can be separated from external changes in root-zone soil to date major changes in the availability of essential base cations associated with a changing environment.

Precipitation collector bias and its effects on temporal trends and spatial variability in National Atmospheric Deposition Program/National Trends Network data

Precipitation samples have been collected by the National Atmospheric Deposition Program's (NADP) National Trends Network (NTN) using the Aerochem Metrics Model 301 (ACM) collector since 1978. Approximately one-third of the NTN ACM collectors have been replaced with N-CON Systems, Inc. Model ADS 00-120 (NCON) collectors. Concurrent data were collected over 6 years at 12 NTN sites using colocated ACM and NCON collectors in various precipitation regimes. Linear regression models of the colocated data were used to adjust for relative bias between the collectors. Replacement of ACM collectors with NCON collectors resulted in shifts in 10-year seasonal precipitation-weighted mean concentration (PWMC) trend slopes for: cations (-0.001 to -0.007 mgL^-1yr^-1), anions (-0.009 to -0.028 mgL^-1yr^-1), and hydrogen ion (+0.689 meqL-¹yr^-1). Larger shifts in NO₃^- and SO₄^-2 seasonal PWMC trend slopes were observed in the Midwest and Northeast US, where concentrations are generally higher than in other regions. Geospatial analysis of interpolated concentration rasters indicated regions of accentuated variability introduced by incorporation of NCON collectors into the NTN.