Abstract  Geochemistry is a key tool in identifying sources of elements for both mineral exploration and environmental purposes. This study evaluates the first systematic regional hydrogeochemical survey for environmental assessments of the classic Andean copper mineral province and the Andina-Los Bronces mining district of Central Chile. One hundred and forty-five water samples were collected systematically in the Valparaiso and Metropolitana Regions of Central Chile, including the capital, Santiago. The concentrations of more than 70 elements and compounds were determined using inductively coupled plasma mass spectrometry (ICP-MS) and ion chromatography (IC) along with the stable isotopes (delta D, delta O-18, delta S-34, delta O-18(SO4), delta N-15 and delta O-18(NO3)) and used to define the geochemical baselines in the area and distinguish between different sources. The geochemistry demonstrates the potential to distinguish between natural (bedrock, hydrothermal alteration and mineralization) and anthropogenic (agriculture, sewage and urban) sources of elements. The distribution patterns of many chemicals show a strong correlation with the presence of evaporitic components (Ca, SO42-, Sr, K, Rb, total dissolved solids (TDS)), hydrothermal alteration and sulphide mineralization (Cu, Zn, Ni, Cd, Co and REEs). High concentrations of nitrate, phosphate and alkalinity occur downstream of agricultural areas and reflect pollution from fertilizers. Overall, the catchment areas affected by mining activities are relatively small and highly localized compared to those affected by agriculture and urban centres.

Abstract  Stabilizing anatase-phase in pure and doped nanocrystalline titania (TiO2) with enhanced photocatalytic activity has been a challenging task. In this report, we synthesize nanocrystalline anatase-TiO2 via the conventional and acid-catalyst-modified sol-gel processes. Three different types of acid-catalysts, HNO3, CH3COOH, and H3PO4, have been utilized for this purpose. The effect of acid-catalyst on the morphological, chemical, and structural evolution of samples has been analyzed using the different analytical techniques. The photocatalytic activity has been measured under the ultraviolet (UV)-radiation exposure by varying the acid-catalyst used, initial dye-concentration, and initial concentration of H3PO4. The maximum photocatalytic activity has been exhibited by the sample processed using the H3PO4 as an acid-catalyst which has been attributed to the ability of PO43- anions to bind strongly with the surface of anatase-TiO2 and their dual-role in the dark and under the UV-radiation exposure leading to the largest amount of dye-adsorption on the surface and highest dye-degradation kinetics.

Abstract  Four dihydroisoxazole prolines and four dihydroisoxazole cyclopentane derivatives were submitted to chiral ligand-exchange chromatographic analysis in the presence of O-benzyl-(S)-serine, as the chiral mobile phase additive to the eluent. The 1.0mM O-benzyl-(S)-serine and 0.5mM Cu(NO3)(2) eluent flowed at 1.0mL/min through a conventional octadecylsilica-based stationary phase maintained at 25 degrees C and provided excellent levels of enantioselectivity and resolution for all the species. By using enantiomers as model compounds, the method was validated revealing that the mixed ternary diastereomeric eluates present slightly different spectroscopic properties. The selected chiral ligand-exchange chromatography method was applied for semi-preparative enantioisolation that allowed the establishment of the k(-)<k(+) enantiomeric elution order.

Abstract  Potential energy surfaces (PESs) for the hydrogen sulfide tetramers and pentamers are shown to be very complex. 11 and 15 different isomers were located on the MP2/6-311++G(d,p) PES of (H2S)(4) and (H2S)(5) respectively. CCSD(T) energy calculations on the MP2 optimized geometries suggest that all tetramers are within 2.0 kcal mol(-1) of the lowest energy structure, while for the pentamers, all structures are found in a 3.5 kcal mol(-1) range. To the best of our knowledge, we report and analyze here for the first time in the scientific literature, a newly found type of very weakly stabilizing intermolecular H2S center dot center dot center dot SH2 interaction. In conjunction with traditional H2S center dot center dot center dot H-S-H hydrogen bonds, these previously unreported H2S center dot center dot center dot SH2 intermolecular contacts dictate cluster structures and energies. Our results reveal a very complicated scenario, where a number of different tetramers and pentamers are very close in energy, rendering impossible the unequivocal identification of the global minimum in each case, and as a consequence, suggesting that the properties of these systems would have contributions from many different structures.

Abstract  The lack of selectivity toward a particular analyte has always been the primary concern regarding CNT-based gas sensors. For that reason, in here we present a gas discrimination strategy that focuses on the electrode-CNT junction. The junction is shown to play a key role in the sensing mechanism. Resistive gas sensors based on horizontal CNT arrays have been fabricated using various designs and different top-contacting metals: Pt, Pd and Au. Arrays of devices have been exposed to a series of gases to monitor their resistive response. It was found for our system that the sensor response does not significantly change as a function of the device design or the available CNT sensing area in between the anchoring electrodes. On the contrary, responses to gases are observed to be specific to each sensor electrode metal. Exposure of locally passivated devices (for which distinct areas have been covered) to NO2, H-2 and NH3 highlights different sensing mechanisms for each gas. Multiplex gas discrimination for room temperature can be achieved by strategically choosing the right metal/CNT combination in a complete sensor system. (C) 2014 Elsevier B.V. All rights reserved.

Abstract  We evaluated the association between spinal PGE(2) and thermal hyperalgesia following repeated stress. Thermal nociception was determined in male Sprague-Dawley rats using the hot-plate test, before and after forced-swimming; non-conditioned rats served as controls. Animals were pretreated with ketoprofen or meloxicam, preferential COX-1 and COX-2 inhibitors, respectively. After the second hot-plate test, we measured serum corticosterone (stress marker), and lumbar spinal PGE(2) (neuroinflammation marker) under peripheral inflammation (1% formalin plantar injection). Stressed rats displayed response latencies 40% shorter and inflammatory spinal PGE2 levels 95% higher than controls. Pretreatment with ketoprofen or meloxicam prevented hyperalgesia and elevation of spinal PGE(2), increasing the escape behavior time during forced swimming 95% respect to saline-treated rats. Corticosterone levels in stressed rats were 97% higher than controls; COX inhibitors reduced them by 84%. PGE(2) could participate in stress-induced hyperalgesia, learned helplessness, and corticosterone production, supporting the use of non-steroidal anti-inflammatory drugs (NSAIDs) for persistent pain associated with chronic stress and depression. (C) 2015 Elsevier Ireland Ltd. All rights reserved.

Abstract  Photooxidation of (CH3)(3)CCHO in the presence of NO2 leads to the formation of CO, CO2, (CH3)(3)CC(O) OONO2 (DMPPN), and (CH3)(3)CONO2. The synthesis of DMPPN and thermal decomposition studies were carried out. Pressure dependence was studied at 293 K from 6.0 to 1000 mbar. Kinetic parameters for DMPPN were determined between 293 and 308K, at total pressures of 9.0 and 1000 mbar. The values found for the activation energy and pre-exponential factor were (109 +/- 3)kJ/mol, 1.7 x 10(15)s(-1), and (117 +/- 3) kJ/mol, 5.2 x 10(16)s(-1) at these pressures, respectively. Thermal stability for DMPPN is similar to peroxyacyl nitrates already identified in the atmosphere, such as peroxyacetyl and peroxypropionyl nitrates. The quantum yield for photolysis at 254 nm of (CH3)(3)CCHO was determined to be 0.60 +/- 0.05. (C) 2014 Published by Elsevier B.V.

Abstract  A di-copper(II) complex of the formula [(dien)Cu(mu-1,6-DAH)Cu(dien)(NO3)(2)](NO3)(2), where mu-1,6-DAH = 1,6-diaminohexane, has been synthesized and characterized by X-ray crystallography, X-ray powder diffraction, thermal gravimetric (TG) and differential thermal analyses, cyclic voltammetry, infrared, ultraviolet visible spectroscopies and elemental analysis methods. It was crystallized in a monoclinic system, space group P2(1)/n, with a = 8.0297(8) , b = 12.4937(14) , c = 15.3786(15) , beta = 102.739(8) and z = 2. Each copper(II) has a square-based pyramidal coordination geometry with four N atoms building the basal plane (three from dien and one from mu-1,6-DAH). TGA study of the complex revealed the compound to be stable up to 245 A degrees C. Electrochemical behavior of complex and enzyme-like catalytic activity of this complex, as a potential functional model for the active site of tyrosinase, was studied extensively. Kinetic studies show that the complex has the maximum enzymatic activity at pH 8, temperature of 40 A degrees C and ionic strength of 50 mM.

Abstract  Denitrification in the groundwater systems of agricultural catchments can provide a substantial 'ecosystem service' by attenuating leached nitrate (NO3-) before it reaches surface water bodies. Samples along a groundwater flow path with low dissolved oxygen and declining NO3- concentrations can indicate the occurrence of denitrification. Isotopic analysis of this NO3- can potentially identify and quantify denitrification activity. In this study, shallow groundwater samples (maximum 5 m below ground surface) were taken from three locations within a small agricultural catchment in the Waikato region of New Zealand. The delta N-15 and delta O-18 values of NO3- were analysed to try to determine where denitrification was occurring and at what rate. Results indicated that denitrification rates varied spatially, but interpretation was confounded by insufficiently understood flow paths and extremely low concentrations of NO3- in reduced groundwater. Seasonal denitrification was observed at a Gley soil site where the soil profile was periodically saturated to near the ground surface and delta N-15-NO3- values reached +28.5 parts per thousand and delta O-18-NO3- values up to +19.6 parts per thousand. In contrast to expectations, NO3- in well-oxidised groundwater samples showed substantial variability in its delta N-15 and delta O-18 isotopic signature. This indicated that the NO3- originated from multiple sources, which restricted the quantification of denitrification. (C) 2015 Elsevier B.V. All rights reserved.

Abstract  Changing emissions can alter the surface O-3 seasonal cycle, as detected from northeastern U.S. (NE) observations during recent decades. Under continued regional precursor emission controls (-72% NE NOx by 2100), the NE surface O-3 seasonal cycle reverses (to a winter maximum) in 21st century transient chemistry-climate simulations. Over polluted regions, regional NOx largely controls the shape of surface O-3 seasonal cycles. In the absence of regional NOx controls, climate warming contributes to a higher surface O-3 summertime peak over the NE. A doubling of the global CH4 abundance by 2100 partially offsets summertime surface O-3 decreases attained via NOx reductions and contributes to raising surface O-3 during December-March when the O-3 lifetime is longer. The similarity between surface O-3 seasonal cycles over the NE and the Intermountain West by 2100 indicates a NE transition to a region representative of baseline surface O-3 conditions.

Abstract  This study was focused on the experimental investigation of the very promising combustion technology called as the oxygen-enhanced combustion (OEC), which uses the oxidant containing higher proportion of oxygen than in the atmospheric air, i.e. more than 21%. The work investigated and compared the characteristics of two OEC methods, namely the premix enrichment and air-oxy/fuel combustion, when the overall oxygen concentration was varied from 21% to 46%. The combustion tests were performed with the experimental two-gas-staged burner of low-NOx type at the burner thermal input of 750 kW for two combustion regimes - one-staged and two-staged combustion. The oxygen concentration in the flue gas was maintained in the neighborhood of 3% vol. (on dry basis). The aim of tests was to assess the impact of the oxidant composition, type of OEC method and fuel-staging on the characteristic combustion parameters in detail. The investigated parameters included the concentration of nitrogen oxides (NOx) in the flue gas, flue gas temperature, heat flux to the combustion chamber wall, and lastly the stability, shape and dimensions of flame. It was observed that NOx emission is significantly lower when the air-oxy/fuel method is used compared to the premix enrichment method. Moreover, when the fuel was staged, NOx emission was below 120 mg/Nm(3) at all investigated oxygen flow rates. Increasing oxygen concentration resulted in higher heating intensity due to higher concentrations of CO2 and H2O. The available heat at 46% O-2 was higher by 20% compared with that at 21% O-2. (C) 2014 Elsevier Ltd. All rights reserved.

Abstract  In the last years, emissions standards for internal combustion engines are becoming more and more restrictive, particularly for NOx and soot emissions from Diesel engines. In order to comply with these requirements, Original Equipment Manufacturers (OEM) have to face with innovative combustion concepts and/or sophisticate after-treatment devices. In both cases, the role of the Engine Management System (EMS) is increasingly essential, following the large number of actuators and sensors introduced and the need to meet customer expectations on performance and comfort. On the other hand, the large number of control variables to be tuned imposes a massive recourse to the experimental testing which is poorly sustainable in terms of time and money. In order to reduce the experimental effort and the time to market, the application of simulation models for EMS calibration has become fundamental. Predictive models, validated against a limited amount of experimental data, allow performing detailed analysis on the influence of engine control variables on pollutants, comfort and performance.

In this paper, a simulation analysis on the impact of injection pattern and Exhaust Gas Recirculation (EGR) rate on fuel consumption, combustion noise, NO and soot emissions is presented for an automotive Common-Rail Diesel engine. Simulations are accomplished by means of a quasi-dimensional multi-zone model of in-cylinder processes. Furthermore a methodology for in-cylinder pressure processing is presented to estimate combustion noise contribution to radiated noise.

Model validation is carried out by comparing simulated in-cylinder pressure traces and exhaust emissions with experimental data measured at the test bench in steady-state conditions. Effects of control variables on engine performance, noise and pollutants are analyzed by imposing significant deviation of EGR rate and injection pattern (i.e. rail pressure, start-of-injection, number of injections). The results evidence that quasi-dimensional in-cylinder models can be effective in supporting the engine control design toward the optimal tuning of EMS with significant saving of time and money.

Abstract  Hydrological conditions are among the most important factors influencing nutrient concentrations in rivers and their fluxes out of the catchments. In the boreal area extreme hydrological conditions are typical with intense floods during the snow-melt period in spring and the base-flow conditions during winter and summer.

In this study we compared nitrate-nitrogen (NO3-N), ammonium-nitrogen (NH4-N) and dissolved organic nitrogen (DON) concentrations and fluxes among summer seasons (June-August) with contrasting hydrology in four small boreal rivers with differing land-use in southern Finland.

For the analysis we selected 3 years of the lowest summer discharge (1999, 2010, 2011) and 3 years of the highest summer discharge (1996, 1998, 2004).

During high discharge summers NH4-N and DON concentrations were on average 187 and 240 % higher than during low discharge summers. Because of large differences in discharge between the summers the flux values of the different N fractions were at maximum 10-20 times higher during high discharge summers. The effect of heavy rains on N loading was clearly demonstrated in summer 2004 when two consecutive floods transported 42 % of the annual NO3-N flux, 44 % of the NH4-N flux and 57 % of the DON flux out of the catchment.

Available nitrogen storages in the studied catchment areas were probably in excess especially during the wet summers when the plant uptake was presumably lower compared to dryer and warmer summers. When the hydrological conditions were suitable for surface and subsurface runoff, the concentrations and fluxes of NO3-N, NH4-N and DON increased substantially.

Abstract  Constantly increase popularity of the reburning process for reduction of NO, emission, forces to investigate the impact of reburning process on the combustion conditions within the large scale industrial pulverized coal (PC) boiler. For that purpose the constantly developed numerical tools, like the Computational Fluid Dynamic (CFD) can be used. Presented paper shows the usability of the combustion of sewage sludge gasification gas within the retrofitted PC boiler for reduction of the NO, emission. In presented level of model complexity no modifications to the boiler construction for reburning process have been introduced. Evaluated results have been compared with specified limitation and requirements posted to the reburning technology in large scale industrial boilers. Presented paper should be seen as a case study where different location of the syngas injection ports and syngas proportion have been investigated. Moreover, the usability of NOx emission model from commercial CFD code has been presented. (C) 2014 Elsevier Ltd. All rights reserved.

Abstract  Fe/SBA-15 catalysts containing iron oxide nanoparticles confined inside silica pores (replicated, internal, poorly crystalline) and grown outside silica grains (external, mainly crystalline hematite) in different proportions are prepared using a single silica support. Fe-species are deposited by the two-solvent technique with two iron salts precursors (Fe(NO3)(3)center dot 9H(2)O, FeCl3 center dot 6H(2)O) and two solvents (cyclohexane, hexane) for 11 wt% of iron. Calcination is performed in reproducible conditions (700 degrees C, 2 degrees C/min, thin bed, in air). SAXS measurements are used to show that the 2D hexagonal structure of the used silica is maintained after Fe-loading and calcination. Ar sorption measurements show that the pores are partially plugged. The oxidation of pure methanol is used as a test reaction to compare photocatalytic properties. H2O2 and visible light both activate the reaction. More active catalysts are formed with hexane associated with FeCl3 center dot 6H(2)O than with Fe(NO3)(3)center dot 9H(2)O. A reversed situation is observed with cyclohexane. Iron leaching (after 1 h 30 of test, up to 3 mg of Fe by mL) is important. These results are expected to be of interest in the exploration of size and shape "nanocatalysis" and to provide a further understanding for the reactions that take place when porous silicas are used as supports. (C) 2015 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.

Abstract  The absolute integral intensity of the IR components of the continuum emission is calculated from the laboratory velocities of photochemical reactions between NO and nonexcited and excited O-3 molecules. The vertical intensity distribution of the continuous radiation spectrum of the upper atmosphere (continuum) in the IR area spans a range of heights of the middle atmosphere from 10 to 15 km. A comparison of the calculated values of the continuum intensity with the results of its spectrophotometric surface measurements in the near-IR spectrum allowed refinement of the coefficient of velocity of the NO-ozone reaction responsible for origination of the continuum emission in the IR spectrum range.

Abstract  The novel bimetallic compound [Cu(bappz)(mu-NC)Ni(CN)(3)]center dot H2O (bappz = 1,4-bis(3-aminopropyl) piperazine) is prepared by the reaction of Cu(NO3)center dot 3H(2)O, bappz, and K-2[Ni(CN)(4)] in water. The complex is characterized by IR spectroscopy and single crystal X-ray diffraction. The neutral [Cu(bappz)(mu-NC)Ni(CN)(3)] complex assumes a cyanide-bridged binuclear structure in which the nickel(II) ion is four-coordinated by carbon atoms from four cyano groups (one of them forms a bridge) in a square planar arrangement, whereas the copper(II) ion is five-coordinated by four bappz nitrogen and one cyanide nitrogen atoms in a distorted square-pyramidal geometry.

Abstract  Imino diacetamide styrene divinyl benzene (IDAA SDVB) resin was synthesized and evaluated for separation of molybdenum (Mo) from simulated dissolver solution of irradiated uranium-aluminium alloy. Detailed studies were carried out to understand the influence of various parameters on sorption of Mo. The kinetics of Mo sorption is found to be fast and the kinetics data fit well to the pseudo-second order kinetic equation. Sorption of Mo is found to decrease with the increase of feed acidity. The loading capacity of resin is determined to be 30 mg g(-1), the sorption isotherm data fit well to the Langmuir model. Batch sorption experiments with simulated dissolver solution showed quantitative uptake of Mo along with some co-extraction of iodine (I). Column runs have demonstrated that co-extracted 'I' could be scrubbed easily with solutions of feed acidity. Finally, sorbed Mo could be eluted with 3.0 M HNO3. XAFS and FT-IR studies of Mo sorbed on to IDAA SDVB resin have shown that Mo is sorbed in the + 6 oxidation state (in the form of MoO42-), wherein the complex attains octahedral geometry with contribution from four oxygen atoms of the molybdate anion and two oxygen atoms of the amidic moiety of the imino-diacetamide ligand.

Abstract  The work presented here characterises the influences of different waste-derived fuels on the combustion process in a microturbine. The two most common types of solid waste are converted into liquids by liquefaction in polyhydric alcohols and by pyrolysis to produce the novel fuels LW (liquefied wood) and TPO (tire pyrolysis oil). Baseline results were obtained with diesel fuel and with raw polyhydric alcohols otherwise used in wood liquefaction process. The original contribution of this analysis is the in-depth comparison of the combustion and emission phenomena of LW and TPO under different operating conditions. The results revealed significantly higher CO (carbon monoxide) and THC (total hydrocarbons) emissions for LW due to its reduced atomisation ability and increased spray penetration in line with the physical and chemical properties of the fuel. The combustion properties of TPO resembled those of diesel fuel in terms of CO and THC. NOx (nitrous oxides) emissions reflected the elemental composition of the fuels. In addition, pronounced soot formation is observed when utilizing TPO, whereas for LW, the opacity measurements are surprisingly low. These results indicate that TPO can be exploited directly in gas turbines, whereas LW requires adaptations in the fuel supply system and a narrower range of operating conditions. (C) 2014 Elsevier Ltd. All rights reserved.

Abstract  Nitrous oxide (N2O) fluxes can increase significantly following small increases in soil water-filled pore space (WFPS). Thus, it is essential to improve our knowledge of this crucial relationship to better model N2O emissions by soils. We studied how much the addition of a gas transport and a gas-liquid equilibrium module to the model of N2O emissions NOE could improve simulation results. A sensitivity analysis of the modified model (NOEGTE: gas transport and equilibrium) was first performed, and then the model was tested with published data of a wetting-drying experiment. Simulated N2O fluxes plotted against WFPS appeared to be bell-shaped during the 7 days simulated, combining the effects of the low N2O production for WFPS < 0.62, and the slow gas diffusion for WFPS > 0.95. The WFPS generating the maximum simulated N2O fluxes shifted with time, from 0.76 after 12 h, to 0.79 after 168 h, because of an increase over time of the gas concentration gradient between the soil surface and the atmosphere. NOEGTE appeared able to capture the pattern of N2O emissions monitored in the experimental data. In particular, N2O peaks during drying were well reproduced in terms of timing, but their magnitudes were often overestimated. They were attributed to the increasing gas diffusivity and N2O exchanges from the liquid phase to the gaseous phase.

Abstract  This paper presents the results of measurements of the concentration of surface ozone and concurrent standard meteorological parameters: total solar radiation, temperature, relative humidity, pressure, wind speed, and vertical and horizontal components of the wind. The data were collected from 2005 to 2010 at stations located in central Poland (Mazowieckie voivodeship): Warszawa (urban), Legionowo (suburban), Granica and Belsk (rural). Furthermore, Granica is situated in the forested area of Kampinoski National Park. Continuously measured surface ozone concentrations demonstrated the well-known diurnal cycle of surface ozone concentration with a maximum in the afternoon and a minimum in the early morning hours. The averaged diurnal variations over six years reveal that the highest concentrations appear at rural stations (Belsk: 55 mu g m-(3) and Granica: 50 mu g m-(3)) and the lowest at the urban station (Warszawa: 41 mu g m-(3)). The threshold for high levels of surface ozone (120 mu g m-(3) per 8 h) was exceeded most often at Granica and Belsk. The occurrence of the ozone "weekend effect," especially at urban stations, has been identified. The difference between weekend and weekday surface ozone concentrations at urban and rural stations was as high as 6.5 mu g m-3 and approximately 2 mu g m-(3), respectively. Using appropriate statistical tools, it has been shown that meteorological conditions have a significant influence on ozone concentration. High correlation coefficients were found between ozone concentration and solar radiation, temperature, relative humidity, and wind speed. The forward stepwise regression model explains up to 75% of the variations in daily surface ozone concentration in terms of meteorological variability in summer and up to 70% in winter. At the same time, a multilayer perceptron neural network model was used to reconstruct the concentration of surface ozone. High correlation coefficients (up to 0.89) indicate that, on the basis of standard meteorological parameters and NO2 concentration, we can determine ozone concentration with high accuracy.

Abstract  Using tetrabutyl titanate, erbium oxide and nitric acid as raw materials, TiO2: Er3+ hollow spheres were prepared with carbon spheres as template. The structures and morphologies of the obtained samples were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), and X-ray diffraction (XRD). The photocatalytic activities were studied by degradation of organic pollutants (rhodamine B, methylene blue, alizarin red, methyl orange) using UV-Vis spectrophotometer. The factors, such as Er3+ dopant concentration, pH of the dye solution, on the photocatalytic activities were discussed. The results showed that uniform and well crystallized TiO2: Er3+ hollow spheres in an anatase phase, with diameter of 120 nm could be obtained via carbon-template method followed by a heat treatment at 600 degrees C for 3 h. The specific surface area of the TiO2: Er3+ hollow spheres was about 60.5 m(2)/g. When the Er3+ dopant concentration was 0.5 mol% of Ti4+ ions in TiO2, the photocatalytic activity of catalyst on the methyl orange was better than the other samples. Among the four different organic pollutants, the photocatalytic activity on the alizarin red was best. TiO2: 0.5mol%Er3+ showed the better photocatalytic properties than the undoped TiO2. The photodegradation efficiency of alizarin red with TiO2: 0.5mol%Er3+ was 30% higher than that with the undoped TiO2 under UV light irradiation.

Abstract  An integrated approach has been developed for the multi-component analysis of indoor PM2.5 collected onto the same quartz fiber filter (QFF) by using an innovative combination of techniques such as inductively coupled sector field plasma mass spectrometry (ICP-SF-MS) with vapor-phase microwave-assisted aqua regia or sonication-assisted water extraction, ion chromatography, thermal-optical transmittance as well as high performance liquid chromatography and enzyme-linked 5,5'-dithio-bis(2-nitrobenzoic acid) assay for the determination of elemental composition, major inorganic ions, elemental/organic carbon (EC/OC) as well as oxidative potential (OP) through ascorbate (AA) and reduced glutathione (GSH) depletion, respectively. The low mass of PM2.5 collectable indoors, the elemental blank values of the QFFs and the sample volume/acidity requirements of the ICP-SF-MS represented a challenge for elemental determination. Finally, this approach was successfully applied for determination of 15 elements (Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rb, Sr, Mo, Cd, Sn and Pb) at the ng m(-3) level in more than two-thirds of indoor PM2.5 (n = 25) collected in mechanically ventilated offices within the European Union project OFFICAIR at increased sampling flow rates (0.6 m(3) h(-1)-2.3 m(3) h(-1)) and sampling time (cca. 100 h) in the acidic/aqueous extracts. The concentration of Cl-, NO3-, SO42-, Na+, NH4+, K+, Ca2+, Mg2+, OC and EC was at the mu g m(-3) level in the aqueous extracts. This new approach aiming at the comprehensive characterization,of low mass indoor PM2.5 samples allowed assessment of OPAA and OPGSH in all samples. The PM2.5 critical sample mass to achieve elemental determination was approximately 400 mu g. (C) 2014 Elsevier B.V. All rights reserved.

Abstract  Surface water quality in the Lower Mississippi River Basin (LMRB) and the adjacent Gulf of Mexico has degraded over the past several decades primarily due to deforestation to agricultural lands and the loss of wetlands. This study investigated the benefits of reforestation upon nitrate-nitrogen (NO3-- - -NN) and orthophosphate (PO43-) load reductions in the Lower Yazoo River Watershed (LYRW) within the LMRB using the BASINS-HSPF model. The model was calibrated and validated with available experimental data prior to its applications. Two simulation scenarios were then performed: one was chosen to predict the NO3-- - -N and PO43- loads without reforestation and the other was selected to estimate the impacts of reforestation upon NO3-- - -N and PO43- load reductions following the conversion of 25, 50, 75, and 100% of the agricultural lands (with most lands near or in the batture of the streams) into forests. In general, an increase in forests reduced NO3-- - -N and PO43- loads and occurred because forest soils enriched in organic matter absorb water and nutrients and reduce the surface water runoff. Overall, a two-fold increase in forest land would result in approximately two-fold decrease in annual average NO3-- - -N and PO43- loads. On average, over a 10-year simulation, the specific NO3-- - -N and PO43- load reductions were, respectively, 0.06 and 0.004 ton/ha/y. Although the annual average NO3-- - -N and PO43- loads always decreased with increasing forest land conversion, the optimal specific NO3-- - -N and PO43- load reductions were found at a 75% reduction of agricultural land for the simulation conditions used in this study. Additionally, the annual average NO3-- - -N load was about 16 times higher than that of PO43- in the LYRW. This study suggests that reforestation in or around the batture of streams is a beneficial practice for NO3-- - -N and PO43- load reductions. Published by Elsevier B.V.

Abstract  A sensitive flow-injection method for the chemiluminescent determination of ultra-low concentration of nitrate in water is presented. Nitrate is on-line photolytically converted to peroxynitrite by absorption of UV light inside of 60 mm long quartz capillary (i.d. 530 mu m, o.d. 720 m). Peroxynitrite is subsequently determined by the chemiluminescent reaction with luminol. The detection limit of nitrate is 7 x 10(-10) M (S/N = 3). The linear range of the method is 2 x 10(-9)-1 x 10(-5) M nitrate. The interference of nitrite is eliminated by its conversion to nitrogen after mixing of sample with a solution of sulfamidic acid. Other common anions do not interfere. The interference of cations is eliminated by passing the sample through a cation-exchange column. The FIA procedure allows analysing of 15 samples per hour. The method was applied to the determination of nitrate in various real water samples. The results are in good agreement with a reference ion chromatographic method.