Impact of organic compounds on the concentrations of liquid water in ambient PM2.5

A field study was undertaken during the summer of 2000 to assess the impact of the presence of organic compounds on the liquid water concentrations of PM_2.5 samples. The selected site, located in Research Triangle Park, North Carolina, was in a semi-rural environment with expected impacts from both biogenic and anthropogenic emissions. Eight samples, collected on Teflon filters over 48-h periods, were analyzed for their liquid water concentrations by using a beta gauge to measure the change in PM_2.5 mass on the filter as a function of relative humidity in a humidity-controlled environmental chamber. The filter samples were also analyzed for mass, elemental and organic carbon, and anionic concentrations. For six of the eight samples, the measured liquid water concentrations exceeded those predicted from the presence of the inorganic constituents. A relationship between the excess liquid water and the measured organic carbon mass was found, although the standard deviations associated with the measurements were large. Through modeling studies it was determined that, on average, about 80% of the liquid water in the PM_2.5 could be accounted for by inorganic ions present, with the remaining 20% associated with organic compounds. The liquid water data were consistent with the presence of aqueous solutions supersaturated with respect to the inorganic ions in the aerosol.     

WATER ACTIVITY IN SOLUTIONS CONTAINING ORGANIC ACIDS

A thermodynamic model for the activity coefficient was used to predict au in some food-related solutions. Water activity values for organic acids solutions (malic, tartaric and citric) were measured experimentally and used to adjust interaction parameters for the UNIFAC model. The partial dissociation phenomenon for weak electrolytes in aqueous systems was considered and concentrations of species were calculated. Predictions of au with mean deviations of 0.26% were obtained.     

Alkylphenol ethoxylates in the environment

A comprehensive monitoring study, sponsored by the Chemical Manufacturers Association and designed in cooperation with the Environmental Protection Agency (EPA), measured the levels of nonylphenol (NP) and its ethoxylates (NPE) in 30 rivers. The sites, all receiving municipal or industrial wastewater, were selected at random from EPA’s United States river reach database by a statistical procedure. Water column and bottom sediment samples were collected along a perpendicular transect at each site. All samples were assayed for NP and NPE₁, and the higher ethoxylates (NPE₂ to NPE₁₇) were determined in the water samples. Analysis was by high-performance liquid chromatography (HPLC) with fluorescence detection of microgram quantities of NPE obtained by extractive steam distillation (NP and NPE₁) or a dualcolumn extraction procedure (NPE₂ to NPE₁₇). Sample collection and analytical procedures were validated according to rigorous EPA guidelines, and quality assurance standards were met throughout the study. NP and NPE concentrations in river water were mostly (60 to 75% of the samples) below their detection limits (about 0.1 ppb for NP, NPE₁, and NPE₂; 1.6 ppb for NPE_3–17). The highest levels found were about 1 ppb for NP, NPE₁, and NPE₂, 15 ppb for NPE_3–17. A majority of sediment samples contained detectable amounts of NP and NPE₁, ranging up to 3000 ppb for NP and 170 ppb for NPE₁. Sediment interstitial water concentrations of NP were estimated to be similar to concentrations in the water column. A portion of this paper was presented at the 1991 Annual AOCS Meeting in Chicago     

Cytochrome P450 Dependent Activities in Mussel and Fish from Coastal Marine Environment: Field Studies on the French Coast of the Mediterranean Sea

Hepatic cytochrome P450 monooxygenase activities including Benzo(a)pyrene hydroxylase (BPH), biomarker of exposure to polycyclic hydrocarbons (PAH) and other organic contaminants like polychlorobiphenyls (PCB) was measured in the microsomal fraction from the fish, Serranus cabrilla (sea comber) liver, and the mussel, Mytilus galloprovincialis, digestive gland. Additionally, ethoxyresorufin-O-deethylase (EROD) activity measurements were made on the same fish samples. The animals were collected from multiple sites on the French Mediterranean coast, exhibiting various degrees of sediment contamination by urban/industrial wastes quantified in term of PAH and PCB sediment content. Mussel BPH, fish BPH and to a lower extent fish EROD activities were tentatively correlated to sediment PAH/PCB content. The presence of low concentration (20 μM) of α-naphthoflavone (ANF) in the assay mixture increased hepatic BPH activity of sea comber. Statistical correlation of hepatic BPH with PAH level in sediment was greater with the presence of ANF. This work demonstrates the potential of mussel to be used in biomonitoring programmes for coastal pollution survey.     

Preconcentration of Heavy Metals and Matrix Elimination using Silica Gel Chemically Modified with 2,3‐Dihydroxybenzaldehyde

Abstract

Many direct methods cannot easily be used to measure analytes such as Cd(II), Cu(II), Ni(II), Pb(II), and Zn(II) ions in sea and river water since these elements are present at very low concentration and the sample has a very complex matrix. In this study a method was developed to preconcentrate these ions by solid phase extraction within a column system using a newly synthesised 2,3‐dihydroxy benzaldehyde modified silica gel (SGDHB). Different parameters, such as pH, resin amount, eluent type, eluent volume, sample flow rate, preconcentration factors, and resin capacity were determined for the preconcentration of metal ions with the resin. Samples (125–500 ml) containing metal ions were passed through the column filled with SGDHB resin so that metal ions were retained on the column. The preconcentrated analytes were then eluted with 15 mL of 0.1 M HCl. The metal concentrations in the eluate were measured by FAAS. A sample and eluent flow rate of 1.12 and 0.56 ml/min respectively was used. Estimates of accuracy, precision, and detection limits were determined. In addition, analysis of the CRM LGC 6156 harbor sediment was undertaken, using the resin to isolate the analytes from potential interferences. Good agreement with certified values was obtained, indicating that the method is equally applicable to the analysis of water samples and to digests of solid materials.     

Water quality of Vistonis Lagoon, Northern Greece: seasonal variation and impact of bottom sediments

The aim of this study is to present the seasonal variation of nutrients in the water column and the bottom sediments of Vistonis Lagoon, a hypereutrophic Mediterranean coastal lagoon located in Northern Greece, and to estimate the impact of bottom sediments on the water quality of this lagoon. Nutrient concentrations in the water column and in bottom sediments were determined throughout seven seasonal sampling cruises from May 2003 to October 2004. Physicochemical parameters, such as transparency, temperature, salinity, pH and dissolved oxygen, were measured in situ in the water column using suitable equipment. Nutrient concentrations in bottom water were found generally higher than those in surface water. Nitrogen, mainly as nitrates, and phosphorus are released into the water column from the bottom sediments, especially during the summer period. Anoxia in the bottom water, as well as resuspension of the sediments are the main factors affecting nutrient internal loading in this lagoon. An approximate calculation showed that total phosphorus release was about 80 mg m⁻² d⁻¹ for the period March–August 2004. Vistonis Lagoon restoration will be possible only through the minimization or elimination of both external and internal nutrient loadings.     

HYDRODYNAMICS AND MASS TRANSFER IN DOWNFLOW BUBBLE COLUMN

Gas holdup, effective interfacial area and volumetric mass transfer coefficient were measured in two and three phase downflow bubble columns. The mass transfer data were obtained using the chemical method of sulfite oxidation, and the gas holdup was measured using the hydrostatic technique. Glass beads and Triton 114 were used to study the effects of solids and liquid surface tension on the gas holdup and the mass transfer parameters a and k_La. The gas holdup in three phase systems was measured for non-wettable (glass bead) and wettable (coal and shale particles) solids.

The mass transfer data obtained in the downflow bubble column were compared with the values published for upflow bubble columns. The results indicate that in the range of superficial gas velocities (0.002-0.025) m/s investigated, the values of the mass transfer coefficient were of the same order of magnitude as those observed in upflow systems, but the values of interfacial area were at least two fold greater. Also, the results showed that the operating variables and the physical properties had different influences on a and k_La in the downflow bubble column. Correlations for a and k_La for the downflow bubble column are proposed which predict the data with adequate accuracy in the range of operating conditions investigated.     

Experimental investigation and modeling of the separation of ternary mixtures by hydrophilic pervaporation

ABSTRACT

In the course of the present study, the pervaporative dehydration of two ternary mixtures: ethanol/n-butanol/water and ethanol/ethyl acetate/water were investigated through hydrophilic polymer composite PERVAP 1210 membrane. The effects of temperature and the concentrations of water and organic components on permeation were studied through pervaporation experiments. The influence of Hansen solubility parameters of the components and mixtures on their permeation was also examined. It has been found that changes of organic ratios in the feed solution affect organic permeation due to mutual interactions and flux coupling. This interaction was built in a suggested semi-empirical mass-transport model for ternary mixtures with optional simplifications. The modeled partial fluxes are in good accordance with the measured values.     

Unsegmented flow approach for on-line monitoring of pH,conductivity, dissolved oxygen and determination of nitrite and ammonia in aquaculture

A fully automated flow system for on-line monitoring of analytes/parameters of interest in aquaculture is described. The approach has been optimized for the photometric determination of nitrite and ammonia and the continuous monitoring of pH, conductivity and dissolved oxygen, but these analytes/parameters are readily changeable as required. The system has been tested by monitoring these species in the input and output sea water streams of tanks at a fish breeding farm and also by monitoring water containing high concentrations of fish feed.     

Simulation Of Ozone Transfer In Water. Comparison With A Pilot Unit

A computer simulation of a bubble column is established to determine the residual ozone concentration in the air and the dissolved ozone residual in the water. This study is aimed to improve the control of ozonation systems, both technically and economically.

The program is based on mass balances along the contact column, which take into account the ozone consumption due to both the self-decomposition and the reactions with organic compounds contained in the water. The experimental measurements allow quantification of the ozone concentration in the air at the inlet and outlet of the pilot unit, as well as the dissolved ozone concentration at different heights along the column. A relation between the transfer coefficient, k_La, and the superficial velocity of the ozonated air is established. It is specific to the diffusion characteristics of the pilot unit. The k_La then is reintroduced in the program.

The calculated and the measured values are shown to be similar regarding the transfer yields, the dissolved ozone concentrations at the pilot unit outlet and the profiles of dissolved ozone concentrations along the contact column. Using the program, the influence of the most important parameters of ozonation on the transfer (treatment rates, initial ozone concentration in the air, pH and organic content of the water, k_La values) have been simulated.     

Investigation of liquid–liquid equilibrium of the ternary system(water +1,6-diaminohexane + 2-methyl-1-propanol or 3-methyl-1-butanol) at different temperatures

In this study, the LLE data of ternary system (water+1,6-diaminohexane+2-methyl-1-propanol) and (water+1,6-diaminohexane+3-methyl-1-butanol) were measured at 293.15, 303.15 and 313.15 K under atmospheric pressure. Reliability of the experimental tie-line data was checked by empirical Hand, Othmer-Tobias and Bachman equations. Distribution coefficient (D) and selectivity (S) were calculated in order to investigate capability of the studied organic solvents for 1,6-diaminohexane extraction. The high values of separation factors demonstrated that 2-methyl-1-propanol and 3-methyl-1-butanol were applicable for this purpose. The experimental data were correlated by nonrandom two-liquid (NRTL) and universal quasi-chemical (UNIQUAC) models. The percent-root-mean-square deviation (RMSD) values for NRTL and UNIQUAC models were less than 0.15, which indicated that the experimental data have been sufficiently correlated.     

Recycling soil nutrients by using channel deposits as fertilizers?

Topsoil constituents are eroded from agricultural sites and leached towards drainage channels. This transfer can affect aquatic ecosystems and deteriorate the efficiency of drainage systems and fertilisers. As long as erosion cannot be completely avoided, the recycling of sediments and associated nutrients may offer a sustainable solution to these problems. The aim of our case study at the island Sant Erasmo, lagoon of Venice (Italy) was to assess the ecological problems and potentials of sediment recycling. With our assessment we concentrated on (1) the origin of channel sediments, (2) the benefit of sediment application for increasing the nutrient stocks of the soils, and (3) the risk of heavy metal (HM) contamination of arable soils by sediment application. Samples from soils of horticultural sites, sediments, and waters from adjacent drainage channels and lagoon sediments were analyzed for the concentrations of nutrients (P and K) and HM (Cu, Pb, and Zn). Potentially available channel sediment masses and element stocks were calculated for the soil fertility classes of Sant Erasmo based on local measurements of sediment depths and analyses of aerial photographs by a geographic information system. In a column experiment, leaching of both nutrients and Cu from recently dredged sediments was analyzed. Heavy metal concentrations of soils and channel sediments were much higher than of lagoon sediments. The similarity of the chemical properties of the channel sediments and of top soil samples implies that topsoil material is eroded into the channels. The amount of sediments accumulated in the channels corresponded to soil erosion rates between 2 and 23?t?ha^?1?a^?1. Channel sediments contained higher concentrations of nutrients and organic carbon but slightly lower concentrations of HM than the soils of adjacent horticultural sites. Sediment P and K yields would be sufficient to replace fertiliser application at the horticultural sites for up to 51 and 35?years, respectively. The column experiment indicated that Cu mobilization induced by oxidation processes is restricted to the first years after sediments are applied to the soils. Our study emphasizes that for a comprehensive assessment of sediment recycling in agricultural systems the available sediment stocks as well as the contents of nutrients and pollutants of the sediment in relation to soils have to be considered.     

Nanofiltration of wastewaters from the fish meal industry

The wastewaters generated in the fish meal industry, a water-intensive industry, contain a high organic load comprising a significant amount of proteins. Therefore, they should not be discharged without a suitable treatment in order to prevent negative impacts in the environment, and allow the recovery of high added value products. The effluent generated in a fish meal plant located in Talcahuano, Chile, was characterized, and pre-treated by microfiltration (MF) cartridges in series (80, 20 and 5 μm). A multi-channel ceramic membrane of 1 kDa MWCO, Kerasep NanoN01A, was used in the nanofiltration (NF) experiments. The operating conditions were optimised in total recycling mode, and the subsequent concentration experiment was carried out at 4 bar, 4 m/s, ambient temperature and natural pH. The results from this work clearly show that NF is an efficient and ecologically suited environmental technology for decontamination and recycling of the wastewaters generated during the fish meal production, as it allows both the recycle of water (permeate stream) and proteins (concentrate stream) into the fish meal process, besides environmental pollution abatement. Although the membrane undergoes severe fouling, it can be effectively cleaned through a basic-acid washing cycle.     

Comparison of Separations of Fatty Acids from Fish Products Using a 30-m Supelcowax-10 and a 100-m SP-2560 Column

Commercial fish oils and foods containing fish may contain trans and/or isomerized fatty acids (FA) produced during processing or as part of prepared foods. The current American Oil Chemists’ Society (AOCS) official method for marine oils (method Ce 1i-07) is based on separation by use of poly(ethylene glycol) (PEG) columns, for example Supelcowax-10 or equivalent, which do not resolve most unsaturated FA geometric isomers. Highly polar 100-m cyanopropyl siloxane (CPS) columns, for example SP-2560 and CP Sil 88 are recommended for separation of geometric FA isomers. Complementary separations were achieved by use of two different elution temperature programs with the same CPS column. This study is the first direct comparison of the separations achieved by use of 30-m Supelcowax-10 and 100-m SP-2560 columns for fatty acid methyl esters (FAME) prepared from the same fish oil and fish muscle sample. To simplify the identification of the FA in these fish samples, FA were fractionated on the basis of the number and type of double bonds by silver-ion solid-phase extraction (Ag⁺-SPE) before GC analysis. The results showed that a combination of the three GC separations was necessary to resolve and identify most of the unsaturated FA, FA isomers, and other components of fish products, for example phytanic and phytenic acids. Equivalent chain length (ECL) values of most FAME in fish were calculated from the separations achieved by use of both GC columns; the values obtained were shown to be consistent with previously reported values for the Supelcowax-10 column. ECL values were also calculated for the FA separated on the SP-2560 column. The calculated ECL values were equally valid under isothermal and temperature-programmed elution GC conditions, and were valuable for confirmation of the identity of several unsaturated FAME in the fish samples. When analyzing commercially prepared fish foods, deodorized marine oils, or foods fortified with marine oils it is strongly recommended that quantitative data acquired by use of PEG columns is complemented with data obtained from separations using highly polar CPS columns.     

Priority Polycyclic Aromatic Hydrocarbons (PAHs): Distribution,Possible Sources and Toxicity Equivalency in Urban Drains

Wastewater from urban areas constitutes one of the major sources of pollutants contributed to aquatic ecosystem. This study was carried out to elucidate the occurrence and possible source of US Environmental Protection Agency identified 16 priority polycyclic aromatic hydrocarbons (PAHs) in water and sediments from the urban wastewater drains in Delhi, India. A total 60 samples (water and sediment) collected during year 2011–2012, and analyzed the following USEPA methods. Water and sediment samples were extracted using liquid-liquid and ultrasonication techniques, respectively. Glass column chromatography with activated silica was used for sample extracts clean-up, followed by quantification on HPLC equipped with diode array detector at 254 nm wavelength using mixture of acetonitrule and water as mobile phase. Concentrations of total 16 PAHs (∑16PAHs) in all drain water samples ranged from 0.29–35.22 μg/L (mean ± SD, 10.83 ± 10.66 μg/L), predominated by two- and three -ring PAHs. The ∑16PAHs concentrations in all collected sediments ranged between 220–19321 μg/kg (mean±SD, 5574 ± 6820 μg/kg) dry weights. High molecular weight PAHs (≥4-ring PAHs) were dominant in sediment samples. Benzo(a)pyrene equivalent (BaPeq), a relative carcinogenic potential to the corresponding PAHs to BaP was estimated and presented. A selected number of concentration ratios of specific PAHs compounds were calculated and used to diagnose the possible sources of PAHs contamination. The diagnostic ratios reflected pyrogenic input from gasoline or diesel powered vehicular emissions as the major source of PAHs. The levels of PAHs observed in water and sediments were compared with similar studies undertaken in other regions of the world.     

Partitioning and pore-filling: Solubility-normalized sorption isotherms of nonionic organic contaminants in soils and sediments

Nonlinear sorption of hydrophobic organic pollutants in soils and sediments can be described by a combination of partitioning and adsorption (pore-filling) mechanisms. Both the partitioning and the pore-filling models plot sorptive uptake vs. solubility-normalized aqueous concentrations, which yields “collapsing” sorption isotherms for similar compounds. With this new concept, sorption of a variety of similar compounds could be predicted based on measured data of one probe chemical. The solubility-normalized Freundlich model predicts an inverse linear relationship between the sorption coefficient measured at a given relative concentration vs. solubility, S, which is demonstrated for 3 partitioning dominated samples from Bangladesh (soil, aquifer sediment, peat) and 4 compounds (carbofuran, trichloroethene, 1,2-dichlorobenzene, phenanthrene) as well as for 2 activated carbons (F300, F400), and a wide variety of compounds (literature data). Future research will focus on the improvement of prediction of sorption in soils and sediments by including other normalization parameters, such as molar volume, polarizability, etc., in addition to the water solubility.     

Nitrate contamination of groundwater: Measurement and prediction

Agriculture makes a significant contribution to the diffuse source contamination of surface and groundwater resources, particularly contributing to the NO ₃ ^- contamination of groundwater. Two approaches were adopted to evaluate management practices (within the context of the whole farming system) for their impacts on the environment : (1) measurement of the quality of groundwater under different farming systems, and (2) comparison of predictions of the impact of farming systems on water quality, obtained using whole farm N budgets, with measured values.The Ontario Farm Groundwater Quality Survey evaluated the rural groundwater quality in Ontario, with respect to common contaminants including NO ₃ ^- . Approximately 1300 domestic farm wells were sampled, and wells were drilled in some fields of farms involved in the study. NO ₃ ^- was present at concentrations above the maximum acceptable for drinking water (10 mg N 1^–1) in 14% of wells, including 7% of wells that also had unacceptable concentrations of coliform bacteria. Significant levels of NO ₃ ^- contamination were observed under most agricultural land use practices investigated.Calculation of N budgets was simplified by assuming that there was no net change in the N content of farm assets. The N inputs to agricultural systems considered were: purchases from off-farm suppliers, N₂ fixation and atmospheric deposition. Symbiotic N₂ fixation was estimated from empirical relationships between crop yield and N₂ fixed. The N outputs were in sales of plant and animal produce, gaseous and leaching losses. Gaseous loss was assumed to result only from volatilization of ammonia, estimated to be 39% of total manure N.We have identified one cash crop farming system where there was a true balance. The rotation included corn soybeans and wheat, with two years of soybean always being grown before corn. Many livestock farms, including two organic farms, gave large imbalances of N which might indicate that these operations were not in equilibrium.The relationship between measured and predicted values of NO ₃ ^- -N expected in the groundwater under the different management systems showed that the simplified N budget overestimated the NO ₃ ^- -N concentration by about one third. However, the budget approach appeared to identify farms where contamination was likely even if the actual amount was over estimated. Simplified budgets could therefore be used to compare the potential of different farming systems for causing environmental contamination.     

Interaction of Silica Particles Through a Liquid

Measurements of the destruction time of the sediment column structure were carried out for different fractions of silica particles in NaCl and CaCl₂ solutions whose concentrations were varied from 0.25 M to 2.0 M. On the basis of this study, linear relationships between the reciprocal of the destruction time of the silica sediment column structure and average diameter of the silica fraction, the density and the work of cohesion of the solutions were found. From these relationships the critical values of the particle diameter, the cohesion work and density of the solutions were determined for the destruction time equal to infinity (1/t = 0). The detachment force of one particle from another, which resulted from gravitational interaction, was calculated using the above critical parameters. For the system whose components have critical values the detachment force is found to be equal to the attachment force resulting from the interfacial interaction. Next, on the basis of our earlier study and Derjaguin's approximation, the radius of the contact plane and the attachment force between two silica particles were calculated. The detachment force decreased with increasing salt concentration, but the attachment force was nearly constant. It was found that, for a given salt concentration, the relationship between the reciprocal of the destruction time and the difference between the detachment and attachment forces was also linear. It appeared that for the silica column structure having critical parameters the values of the difference between the detachment and attachment forces were negative. This means that in the calculation of the attachment force between silica particles in the studied solutions an additional interaction should be taken into account.     

Evaluation of the weathering performance of basecoat/clearcoat automotive paint systems by electrochemical properties measurements

The aim of the present study was to investigate the possibility of evaluating the weathering performance of a basecoat/clearcoat automotive paint system through the determination of its electrochemical properties. To this end, the electrochemical properties of a basecoat/clearcoat automotive paint in a 3.5% solution of NaCl in deionized water were measured at different weathering exposure times. A constant phase element (CPE) was used for describing the electrochemical behavior of the coatings under test. The values of the CPE parameters, i.e. Y₀ (the CPE constant) and n (the CPE power) were subsequently correlated to the extent of photo-oxidation (as measured by appearance, surface roughness, FTIR, surface tension and adhesion measurements) of clearcoat at the surface, in the bulk and at the interface between the basecoat and the clearcoat. The result showed that the electrochemical parameters Y₀ and n provide ready means for comparing the weathering performances of basecoat/clearcoat automotive paint systems. Increases in the value of Y₀ together with decreases in the value of n with increasing weathering exposure times suggest increased possibilities for the onset of cracking in the clearcoat itself in addition to its propagation towards the basecoat. Additionally, sudden variations in the values of Y₀ and n are indicative of increases for the clearcoat to peel off.     

醋酸酐与水在化学反应量热方法确认中的应用

热流法化学反应量热测试获取的目标反应热（ΔH）、反应体系比热容（c_p）和最大热累积度（X_ac）等热安全参数是精细化工反应安全风险评估中不可或缺的关键参数,其测试结果的准确度（即正确度与精密度）直接影响化学反应的工艺危险度分级。目前关于测得的化学反应热安全参数准确度和有效性的研究未见报道。为解决这一问题,提出了以醋酸酐和水作为参考物质,采用“变异系数（CV值）法” 和“道格拉斯（Grubbs）检验法”分别验证热流法反应量热测试醋酸酐水解反应的ΔH、C_p 、X_ac等参数的精密度（即重复性和再现性偏差）,采用“t验证法”评估热流法反应量热测试水的比热容的正确度。研究结果表明：热流法反应量热测试醋酸酐水解反应的ΔH、C_p 、X_ac等参数在同一实验室内的重复性标准偏差和与其他4家实验室比对的再现性标准偏差均满足要求;采用热流法量热测试得到25℃水的比热容数据与标准比热容值t验证结果不存在实质性偏倚。因此,测试结果的精密度和正确度均满足要求。