Abstract  Progress on reducing nutrient loss from annual croplands has been hampered by perceived conflicts between short-term profitability and long-term stewardship, but these may be overcome through strategic integration of perennial crops. Perennial biomass crops like switchgrass can mitigate nitrate-nitrogen (NO3-N) leaching, address bioenergy feedstock targets, and - as a lower-cost management alternative to annual crops (i.e., corn, soybeans) - may also improve farm profitability. We analyzed publicly available environmental, agronomic, and economic data with two integrated models: a subfield agroecosystem management model, Landscape Environmental Assessment Framework (LEAF), and a process-based biogeochemical model, DeNitrification-DeComposition (DNDC). We constructed a factorial combination of profitability and NO3-N leaching thresholds and simulated targeted switchgrass integration into corn/soybean cropland in the agricultural state of Iowa, USA. For each combination, we modeled (i) area converted to switchgrass, (ii) switchgrass biomass production, and (iii) NO3-N leaching reduction. We spatially analyzed two scenarios: converting to switchgrass corn/soybean cropland losing >US$ 100 ha(-1) and leaching >50 kg ha(-1) (conservative scenario) or losing >US$ 0 ha(-1) and leaching >20 kg ha(-1) (nutrient reduction scenario). Compared to baseline, the conservative scenario resulted in 12% of cropland converted to switchgrass, which produced 11 million Mg of biomass and reduced leached NO3-N 18% statewide. The nutrient reduction scenario converted 37% of cropland to switchgrass, producing 34 million Mg biomass and reducing leached NO3-N 38% statewide. The opportunity to meet joint goals was greatest within watersheds with undulating topography and lower corn/soybean productivity. Our approach bridges the scales at which NO3-N loss and profitability are usually considered, and is informed by both mechanistic and empirical understanding. Though approximated, our analysis supports development of farm-level tools that can identify locations where both farm profitability and water quality improvement can be achieved through the strategic integration of perennial vegetation.

Abstract  In this study, the methanol extract of Artemisia scoparia was evaluated for its protective potential against carbon tetrachloride (CCl4)-induced hepatic toxicity. Seven groups of mature albino rats were used in the course of the experiment and each group was treated with specific doses of plant extract and CCl4. Silymarin was used as a standard protective drug. The results of the experiment revealed that Artemisia scoparia plant extract was successful in fighting CCl4 toxicity as it clearly reduced the elevated levels of liver serum markers (alkaline phosphatase and alkaline aminotransferase), lipid peroxidation, nitrite content, and H2O2 on one side while enhancing the levels of antioxidant enzymes (catalase, peroxidase, superoxide dismutase, glutathione-s-transferase, gamma-Glutamyltranspeptidase, and glutathione reductase) and protein content. It also protected DNA from the damaging effects of CCl4. The findings of this study demonstrate that Artemisia scoparia plant extract plays a significant role in preventing the hepatic damages instigated with CCl4 and can be used as a protective agent against oxidative stress-associated disorders.

Abstract  The photochemical degradation of two azo and two anthraquinonic dyes was performed using potassium peroxymonosulphate (Oxone®) activated by UV radiation. The fast decolourization of all dyes was observed within 6 min of UV irradiation, with corresponding dye decays higher than 80%. The kinetic rate constants of the dyes' decay were determined, along with the energetic efficiency of the photochemical treatment, taking into account the influence of a few anions commonly present in real wastewaters (i.e., chloride, nitrate, carbonate/bicarbonate and phosphate ions). Chloride and carbonate/bicarbonate ions enhanced dye degradation, whereas phosphate ions exerted an inhibitory effect, and nitrates did not have a predictable influence. The dye decolourization was not associated with efficient mineralization, as suggested by the lack of a significant total organic carbon (TOC) decrease, as well as by the low concentrations of a few detected low molecular weight by-products, including nitrate ions, formaldehyde and organic acids. High molecular weight by-products were also detected by mass spectrometry analysis. The investigated process may be proposed as a convenient pre-treatment to help dye degradation in wastewater during combined treatment methods.

Abstract  The relative roles of anthropogenic nitrogen (N) deposition and climate change in causing ecological change in remote Arctic ecosystems, especially lakes, have been the subject of debate over the last decade. Some palaeoecological studies have cited isotopic signals (delta N-15)) preserved in lake sediments as evidence linking N deposition with ecological change, but a key limitation has been the lack of co-located data on both deposition input fluxes and isotopic composition of deposited nitrate (NO3-). In Arctic lakes, including those in western Greenland, previous palaeolimnological studies have indicated a spatial variation in delta(N-15) trends in lake sediments but data are lacking for deposition chemistry, input fluxes and stable isotope composition of NO3-. In the present study, snowpack chemistry, NO3- stable isotopes and net deposition fluxes for the largest ice-free region in Greenland were investigated to determine whether there are spatial gradients from the ice sheet margin to the coast linked to a gradient in precipitation. Late-season snowpack was sampled in March 2011 at eight locations within three lake catchments in each of three regions (ice sheet margin in the east, the central area near Kelly Ville and the coastal zone to the west). At the coast, snowpack accumulation averaged 181mm snow water equivalent (SWE) compared with 36mm SWE by the ice sheet. Coastal snowpack showed significantly greater concentrations of marine salts (Na+, Cl-, other major cations), ammonium (NH4+; regional means 1.4-2.7 mu mol L-1), total and non-sea-salt sulfate (SO42-; total 1.8-7.7, non-sea-salt 1.0-1.8 mu mol L-1/than the two inland regions. Nitrate (1.5-2.4 mu mol L-1/showed significantly lower concentrations at the coast. Despite lower concentrations, higher precipitation at the coast results in greater net deposition for NO3- as well as NH4+ and non-sea-salt sulfate (nss-SO42-) relative to the inland regions (lowest at Kelly Ville 6, 4 and 3; highest at coast 9, 17 and 11 mol ha(-1) a(-1) of NO3-, NH4+ and nss-SO42- respectively). The delta(N-15) of snowpack NO3- shows a significant decrease from inland regions (5.7 parts per thousand at Kelly Ville) to the coast (-11.3 parts per thousand). We attribute the spatial patterns of delta(N-15) in western Greenland to post-depositional processing rather than differing sources because of (1) spatial relationships with precipitation and sublimation, (2) within catchment isotopic differences between terrestrial snowpack and lake ice snowpack, and (3) similarities between fresh snow (rather than accumulated snowpack) at Kelly Ville and the coast. Hence the delta(N-15) of coastal snowpack is most representative of snowfall in western Greenland, but after deposition the effects of photolysis, volatilization and sublimation lead to enrichment of the remaining snowpack with the greatest effect in inland areas of low precipitation and high sublimation losses.

Abstract  The goal of this study was to examine the impact of simulated atmospheric aging on the oxidative potential of inorganic aerosols comprised primarily of crustal materials. Four soil samples and one coal fly ash sample were artificially aged in the laboratory through exposure to the vapor from 15.8 M nitric acid solution for 24 h at room temperature. Native and acid-aged samples were analyzed with a cellular macrophage and acellular dithionthreitol assays to determine oxidative potential. Additionally, the samples were analyzed to determine the concentration of 50 elements, both total and the water-soluble fraction of these elements by Sector Field Inductively Coupled Plasma Mass Spectrometry (SF-ICMS) and crystalline mineral composition using X-ray Diffraction (XRD). The results show that reactions with gaseous nitric acid increase the water-soluble fraction of many elements, including calcium, iron, magnesium, zinc, and lead. The mineral composition analysis documented that calcium-rich minerals present in the soils (e.g., calcite) are converted into different chemical forms, such as calcium nitrate (Ca(NO3)(2)). The nitric acid aging process, which can occur in the atmosphere, leads to a 200-600% increase in oxidative potential, as measured by cellular and acellular assays. This laboratory study demonstrates that the toxic effects of aged versus freshly emitted atmospheric dust may be quite different. In addition, the results suggest that mineralogical analysis of atmospheric dust may be useful in understanding its degree of aging.

Abstract  Two new uranyl diphosphonates, namely, [UO2( H3L1)(2)( H2O)]center dot 4H(2)O (1) and [UO2(H3L2)( H2O)]center dot 3H(2)O(2)), H4L1 = PyNHCH(PO3H2)(2), H5L2 = Py(COOH) NHCH(PO3H2)(2), have been hydrothermally synthesized from the reactions of two diphosphonate ligands with uranyl nitrate hexahydrate and characterized systematically using powder and single-crystal X-ray diffraction, IR, EA, TGA and fluorescent emission measurements. The proton transfer from the phosphonic acid groups to the pyridine and imine groups leads to the formation of zwitterionic ligands. The diphosphonate ligand in compound I adopts chelate coordination mode resulting in molecular structure while displays chelate-bridging coordination mode in compound 2 leading to the formation of 1D infinite chain structure. The fluorescent properties of compounds 1 and 2 were also investigated. (C) 2018 Elsevier B.V. All rights reserved.

Abstract  Biostimulation to induce reduction of soluble U(VI) to relatively immobile U(IV) is an effective strategy for decreasing aqueous U(VI) concentrations in contaminated groundwater systems. If oxidation of U(IV) occurs following the biostimulation phase, U(VI) concentrations increase, challenging the long-term effectiveness of this technique. However, detecting U(IV) oxidation through dissolved U concentrations alone can prove difficult in locations with few groundwater wells to track the addition of U to a mass of groundwater. We propose the 238U/235U ratio of aqueous U as an independent, reliable tracer of U(IV) remobilization via oxidation or mobilization of colloids. Reduction of U(VI) produces 238U-enriched U(IV), whereas remobilization of solid U(IV) should not induce isotopic fractionation. The incorporation of remobilized U(IV) with a high 238U/235U ratio into the aqueous U(VI) pool produces an increase in 238U/235U of aqueous U(VI). During several injections of nitrate to induce U(IV) oxidation, 238U/235U consistently increased, suggesting 238U/235U is broadly applicable for detecting mobilization of U(IV).

Abstract  Tropospheric O-3 can impact soil systems mediated by changing root biomass and exudates. This study investigated how elevated O-3 alters soil CO2 and N2O emissions from a winter wheat field. Winter wheat (Triticwn aestivum L.) were fumigated using elevated O-3 concentration (EO3) and using ambient air within open-top chambers during 2015 and 2016. Soil CO2 and N2O emissions were measured using a static closed-chamber technique. Rhizosphere soils were collected to determine dissolved organic carbon (DOC) content, ammonium nitrogen (NH4+-N) and nitrate-nitrogen (NO3--N) concentrations, microbial biomass carbon (MBC) and nitrogen (MBN), and activities of nitrate reductase (NR), nitrite reductase (NiR) and hydroxylamine reductase (HR). Moreover, volumetric soil water content (theta(v)) was monitored and plant dry biomass was quantified. The EO3 treatment exhibited decreased CO2 and increased N2O emissions from winter wheat soil. Soil NH4+-N, NO3--N, NR and NiR increased under EO3, whereas DOC, MBC, MBN and HR decreased. Soil 61, was higher under EO3 before irrigation, due to reduced transpiration. Elevated O-3 decreased soil CO2 flux potentially due to reduced root biomass and associated carbon input. It increased N2O fluxes apparently through enhanced de nitrification due to greater substrate availability and soil theta(v), despite the inhibition of nitrification-related routes.

Abstract  Emissions of nitrogen oxide (NOx = NO + NO2) from the photolysis of nitrate (NO3) in snow affect the oxidising capacity of the lower troposphere especially in remote regions of high latitudes with little pollution. Current air-snow exchange models are limited by poor understanding of processes and often require unphysical tuning parameters. Here, two multiphase models were developed from physically based parameterisations to describe the interaction of nitrate between the surface layer of the snowpack and the overlying atmosphere. The first model is similar to previous approaches and assumes that below a threshold temperature, T-o, the air-snow grain interface is pure ice and above T-o a disordered interface (DI) emerges covering the entire grain surface. The second model assumes that air-ice interactions dominate over all temperatures below melting of ice and that any liquid present above the eutectic temperature is concentrated in micropockets. The models are used to predict the nitrate in surface snow constrained by year-round observations of mixing ratios of nitric acid in air at a cold site on the Antarctic Plateau (Dome C; 75 degrees 06' S, 123 degrees 33' E; 3233ma.s.l.) and at a relatively warm site on the Antarctic coast (Halley; 75 degrees 35'S, 26 degrees 39' E; 35 ma.s.l). The first model agrees reasonably well with observations at Dome C (C-v(RMSE) = 1.34) but performs poorly at Halley (C-v(RMSE) = 89.28) while the second model reproduces with good agreement observations at both sites (C-v(RMSE) = 0.84 at both sites). It is therefore suggested that in winter air-snow interactions of nitrate are determined by non-equilibrium surface adsorption and co-condensation on ice coupled with solid-state diffusion inside the grain, similar to Bock et al. (2016). In summer, however, the air-snow exchange of nitrate is mainly driven by sol-vation into liquid micropockets following Henry's law with contributions to total surface snow NO3 concentrations of 75 and 80 % at Dome C and Halley, respectively. It is also found that the liquid volume of the snow grain and air-micropocket partitioning of HNO3 are sensitive to both the total solute concentration of mineral ions within the snow and pH of the snow. The second model provides an alternative method to predict nitrate concentration in the surface snow layer which is applicable over the entire range of environmental conditions typical for Antarctica and forms a basis for a future full 1-D snowpack model as well as parameterisations in regional or global atmospheric chemistry models.

Abstract  Nitrifier denitrification is the reduction of nitrite (NO2-) by ammonia-oxidizing bacteria. This process may account for up to 100% of nitrous oxide (N2O) emissions from ammonium (NH4+) in soils and is more significant than classical denitrification under some conditions. Investigations of nitrifier denitrification have expanded in the last decade but many aspects are still not understood. In this review, we revisit our 2001 paper, present a comprehensive summary of current knowledge concerning nitrifier denitrification, and identify the many research needs. Nitrifier denitrification can be distinguished from other routes of N2O production using isotopic methods: either isotopomer techniques or a combination of N-15 and 180 tracers. Our understanding of the regulation and conditions favouring nitrifier denitrification has improved over the last decade as a result of adopting molecular and modelling approaches. Environments low in oxygen, and especially those with fluctuating aerobic-anaerobic conditions, promote N2O production by nitrifier denitrification. Also, large NO2- concentrations, which often arise following inputs of ammonium or urea, may be linked to changes in aerobicity and high pH and favour nitrifier denitrification. The effects of temperature and carbon contents on nitrifier denitrification are incompletely understood and future research needs include: the study of pathways similar to nitrifier denitrification in archaea and nitrite oxidizers; the effects of interactions among microorganisms and between microorganism and plants; and the regulation and importance of the enzymes involved. A comparison and evaluation of the methods used for differentiating the sources of N2O is urgently needed. Furthermore, results from studies of freshwater and marine environments as well as wastewater treatment, where nitrifier denitrification is also known as nitrous aerobic denitritation (up to N2O) or aerobic denitritation (up to N-2), will further advance our understanding.

Abstract  The use of nitrification inhibitors with fertilizer N application is an attempt to improve corn (Zea mays L.) N use efficiency while reducing environmental and economic concerns associated with N losses. The objective of this study was to evaluate if the encapsulated formulation of nitrapyrin [2-chloro-6-(trichloromethyl) pyridine], Instinct nitrification inhibitor, would influence corn growth and production when applied with spring pre-plant urea-ammonium nitrate solution (UAN). A 3-yr field study was conducted in a randomized complete block design with four replications of a factorial combination consisting of UAN at six incremental N rates (0-225 kg N ha(-1)), broadcast-incorporated and injected, and with and without 2.56 L ha(-1) (0.56 kg a.i. ha(-1)) Instinct. In 1 of 3 yr, as well as for the means across years, Instinct applied with UAN had a negative effect of reduced early growth plant height and lower mid-vegetative canopy normalized difference vegetative index (NDVI) compared with UAN without Instinct. Corn grain yield also had a lower across N rate mean yield with Instinct application in 2 of 3 yr and across all 3 yr. The economic optimum N rate (EONR) with Instinct was 32 kg N ha(-1) higher than without Instinct, applied either broadcast or injected. Because Instinct did not provide positive effects on corn growth and yield, the study results indicate that Instinct use with spring preplant applied UAN solution would not be an effective nitrification inhibitor to enhance fertilizer N supply or corn production.

Abstract  Fine powders of ammonium nitrate were prepared by the freeze-drying of a solution in a THF-water mixture. Freezing gives a THF hydrate and dispersed ammonium nitrate particles; the THF hydrate can be then removed by sublimation to leave fine ammonium nitrate powder. To optimize the process, the stability of cubic structure II THF clathrate hydrate in the presence of ammonium nitrate was studied by X-ray diffraction and thermal analysis.

Abstract  Common aquaculture practices include the use of certain pharmaceuticals such as antibiotics in avoiding diseases and promoting a healthier growth of the culture. The aim of this study is to monitor and assess the influence of different low oxytetracycline concentrations on the transformation of nitrogen compounds under aeration condition in a lab-scale recirculating aquaculture system (RAS). Over 1 mg L-1 dose of oxytetracycline to aquaculture had induced ammonia(NH4-N), nitrate(NO3-N), soluble COD accumulation in RAS. In addition, nitrous oxide (N2O) emission from RAS was significantly reduced during the oxytetracycline dose periods. After ceasing the dose of oxytetracycline, ammonia oxidation and nitrous oxide re-emission were observed. This observation indicated that low concentrations of oxytetracycline could affect the nitrogen species in RAS. Also, the emission mechanisms of N2O may not be only dependent on nitrification process but also dependent on denitrification process in our RAS system.

Abstract  The diverse abilities such as the antioxidant effect of cerium oxide nanoparticles (CeO2-NPs) have encouraged researchers to pursue CeO2-NPs as a therapeutic agent to treat a number of diseases, including cancer and diabetes. The synthesis method of CeO2-NPs affected on its abilities. In this study, nanosize ceria powders were synthesized by combustion of aqueous containing corresponding cerium nitrate, ammonium nitrate, and glycine redox mixtures. Solution combustion synthesis is a fast and cost-efficient process with high purity product. The crystallite structures were characterized by various methods, including X-ray diffraction technique, high-resolution scanning electron microscopy, transmission electron microscopy, and UV-vis spectroscopy technique. The combustion was flaming and yields voluminous oxides with nano size (20-30 nm). In addition, no diffraction patterns that are characteristic of impurities were observed, indicating the purity of the CeO2-NPs. In vitro cytotoxicity studies on L929 cells, a non-toxic effect in all concentration (up to 1000 mu g/mL) was indicated and it can be believed that this nanoparticle will have viable applications in different medical fields.

Abstract  This study assesses the effects of particle size and season on the content of the major inorganic and organic aerosol ionic components in the Iasi urban area, north-eastern Romania. Continuous measurements were carried out over 2016 using a cascade Dekati low-pressure impactor (DLPI) performing aerosol size classification in 13 specific fractions over the 0.0276-9.94 mu m size range. Fine-particulate Cl-, NO3-, NH4+ , and K+ exhibited clear minima during the warm season and clear maxima over the cold season, mainly due to trends in emission sources, changes in the mixing layer depth and specific meteorological conditions. Fine-particulate SO42- did not show much variation with respect to seasons. Particulate NH4+ and NO3- ions were identified as critical parameters controlling aerosol chemistry in the area, and their measured concentrations in fine-mode (PM2.5) aerosols were found to be in reasonable good agreement with modelled values for winter but not for summer. The likely reason is that NH4NO3 aerosols are lost due to volatility over the warm season. We found that NH4+ in PM2.5 is primarily associated with SO42- and NO3- but not with Cl-. Actually, indirect ISORROPIA-II estimations showed that the atmosphere in the Iasi area might be ammonia rich during both the cold and warm seasons, enabling enough NH3 to be present to neutralize H2SO4, HNO3, and HCl acidic components and to generate fine-particulate ammonium salts, in the form of (NH4)(2)SO4, NH4NO3, and NH4Cl. ISORROPIA-II runs allowed us to estimate that over the warm season similar to 35% of the total analysed samples had very strongly acidic pH (03), a fraction that rose to similar to 43% over the cold season. More-over, while in the cold season the acidity is mainly accounted for by inorganic acids, in the warm ones there is an important contribution by other compounds, possibly organic. Indeed, changes in aerosol acidity would most likely impact the gasparticle partitioning of semi-volatile organic acids. Overall, we estimate that within the aerosol mass concentration the ionic mass brings a contribution as high as 40.6 %, with the rest still being unaccounted for.

Abstract  A well-evaluated Comprehensive Air quality Model with extensions (CAMx) was used to simulate concentrations of secondary inorganic aerosols in fine particulate matter (PM2.5) over Pearl River Delta (PRD) region during two separate months (April and October) in 2013. An indicator of adjusted gas ratio (AdjGR) was used to characterize PM chemistry under both NH3-poor (NP) and NH3-rich (NR) conditions as well as to identify their respective spatiotemporal patterns at different PM2,5 levels. The results were as follows: (1) Based on both observed molar ratio of [NH4+/]/[SO42-] and modeled AdjGR, NR and NP conditions exhibited diurnal, daily, and seasonal variations. (2) A larger area in PRD had NP conditions over the two months when pollution was apparent; this NP region tended to occur downwind of PRD in October and the central region of PRD in April, with high PM2.5 concentrations in both. (3) This wider NP distribution could be related to higher nitrogen oxidation ratio (NOR), with more NOx converting to nitrate. Under conditions of higher pollution, there were relative lower degree of sulfate neutralization (DSN) and particle neutralization ratio (PNR). This supports the claim that NH3 may not be fully neutralized by SO42-. (4) Modeled AdjGR displayed clear hourly variations, with the lowest levels occurring in the afternoon. Reducing NH3 emission is not as efficient as NOx at increasing evening nitrate concentrations. (5) To mitigate PM2.5 pollution even further, a greater reduction of NH3 should be suggested in chemical regions transiting to NR condition when there are lower SO2 and NOx emissions.

Abstract  Estimates of light extinction and visibility are routinely performed by the U.S. Interagency Monitoring of Protected Visual Environments (IMPROVE) network using a simple algorithm which assesses light extinction coefficient (b(ext)) at remote and rural sites from concentrations of major particulate matter (PM) species, NO2, and Rayleigh scattering from clear-air gaseous components. Following the same approach, in this paper an equation with tailored (i.e. site-specific) coefficients was implemented with the aim of reducing uncertainties and assumptions of the IMPROVE algorithm for applications at polluted urban sites. Major differences compared to IMPROVE algorithm are: 1) dry mass extinction efficiencies calculated using a discrete dipole approximation code with aerosol size distributions measured at our monitoring site as input data; 2) site-specific water growth functions computed separately for ammonium sulfate, ammonium nitrate, and organic matter; 3) fine soil evaluated using an equation previously adopted at our urban site; 4) aerosol absorption component assessed directly through filter-based optical measurements. Details about the calculations performed are reported in the paper and the comparison with the IMPROVE revised algorithm is discussed.

The tailored approach here proposed to estimate reconstructed light extinction was applied to PM2.5 test samples collected on purpose in Milan (Italy), where heavy pollution episodes occur during winter periods. In addition, visual range was calculated applying the Koschmieder equation and compared to visibility measured at the nearby Milano-Linate airport obtaining a fairly good correlation.

Abstract  The chemical composition of aerosol particles is a key aspect in determining their impact on the environment. For example, nitrogen-containing particles impact atmospheric chemistry, air quality, and ecological N deposition. Instruments that measure total reactive nitrogen (N-r = all nitrogen compounds except for N-2 and N2O) focus on gas-phase nitrogen and very few studies directly discuss the instrument capacity to measure the mass of N-r-containing particles. Here, we investigate the mass quantification of particle-bound nitrogen using a custom N-r system that involves total conversion to nitric oxide (NO) across platinum and molybdenum catalysts followed by NO-O-3 chemiluminescence detection. We evaluate the particle conversion of the N-r instrument by comparing to mass-derived concentrations of size-selected and counted ammonium sulfate ((NH4)(2)SO4), ammonium nitrate (NH4NO3), ammonium chloride (NH4Cl), sodium nitrate (NaNO3), and ammonium oxalate ((NH4)(2)C2O4) particles determined using instruments that measure particle number and size. These measurements demonstrate N-r-particle conversion across the N-r catalysts that is independent of particle size with 98 +/- 10 % efficiency for 100-600 nm particle diameters. We also show efficient conversion of particle-phase organic carbon species to CO2 across the instrument's platinum catalyst followed by a nondispersive infrared (NDIR) CO2 detector. However, the application of this method to the atmosphere presents a challenge due to the small signal above background at high ambient levels of common gas-phase carbon compounds (e.g., CO2). We show the N-r system is an accurate particle mass measurement method and demonstrate its ability to calibrate particle mass measurement instrumentation using single-component, laboratory-generated, N-r-containing particles below 2.5 mu m in size. In addition we show agreement with mass measurements of an independently calibrated online particle-into-liquid sampler directly coupled to the electrospray ionization source of a quadrupole mass spectrometer (PILS-ESI/MS) sampling in the negative-ion mode. We obtain excellent correlations (R-2 = 0.99) of particle mass measured as N-r with PILS-ESI/MS measurements converted to the corresponding particle anion mass (e.g., nitrate, sulfate, and chloride). The N-r and PILS-ESI/MS are shown to agree to within similar to 6 % for particle mass loadings of up to 120 mu g m(-3). Consideration of all the sources of error in the PILS-ESI/MS technique yields an overall uncertainty of +/- 20 % for these single-component particle streams. These results demonstrate the N-r system is a reliable direct particle mass measurement technique that differs from other particle instrument calibration techniques that rely on knowledge of particle size, shape, density, and refractive index.

Abstract  Application of nitrogen (N) fertilizers, predominantly as urea, is a major source of reactive N in the environment, with wide ranging effects including increased greenhouse gas accumulation in the atmosphere and aquatic eutrophication. The soil microbial community is the principal driver of soil N cycling; thus, improved understanding of microbial community responses to urea addition has widespread implications. We used next-generation amplicon sequencing of the 16S rRNA gene to characterize bacterial and archaeal communities in eight contrasting agricultural soil types amended with 0, 100, or 500 μg N g-1 of urea and incubated for 21 days. We hypothesized that urea amendment would have common, direct effects on the abundance and diversity of members of the microbial community associated with nitrification, across all soils, and would further affect the broader heterotrophic community resulting in decreased diversity and variation in abundances of specific taxa. Significant (P < 0.001) differences in bacterial community diversity and composition were observed by site, but amendment with only the greatest urea concentration significantly decreased Shannon indices. Expansion in the abundances of members of the families Microbacteriaceae, Chitinophagaceae, Comamonadaceae, Xanthomonadaceae, and Nitrosomonadaceae were also consistently observed among all soils (linear discriminant analysis score ≥ 3.0). Analysis of nitrifier genera revealed diverse, soil-specific distributions of oligotypes (strains), but few were correlated with nitrification gene abundances that were reported in a previous study. Our results suggest that the majority of the bacterial and archaeal community are likely unassociated with N cycling, but are significantly negatively impacted by urea application. Furthermore, these results reveal that amendment with high concentrations of urea may reduce nitrifier diversity, favoring specific strains, specifically those within the nitrifying genera Nitrobacter, Nitrospira, and Nitrosospira, that may play significant roles related to N cycling in soils receiving intensive urea inputs.

Abstract  This paper presents a comparison of the performance for three configurations of double effect absorption refrigeration systems with single effect one using ammonia lithium nitrate (NH3/LiNO3) and ammonia sodium thiocyanate (NH3/NaSCN) as working solutions. The effect of operating parameters on COP and exergetic efficiency of the cycles is investigated. In order to avoid error in estimation of solutions enthalpy and entropy at high temperatures, linear equations for specific heat of solutions are obtained from correlating the experimental data. Furthermore, the effects of operating parameters on crystallization possibility are studied. The COP of double effect systems are maximum 60% more, but exergetic efficiency is maximum 16% less than those for single effect cycles. The NH3/LiNO3 systems compared to the NH3/NaSCN systems can perform at lower generator temperatures with higher COP and exergetic efficiency. Operating range of NH3/LiNO3 system is wider, since it is limited for NH3/NaSCN cycle because of crystallization occurrence.

Abstract  Field trials were conducted at gated pipe surface and overhead irrigation sites established to cotton (Gossypium hirsutum L.) to evaluate irrigation and fertigation management using a model-based control system. The control strategies determined the timing and volume of irrigation, and the rate of fertilizer-N to apply through fertigation. For this, nitrogen (N) was applied in-crop season using urea ammonium nitrate (UAN, 30% N solution) at a rate of 40 kg ha(-1) N. At the furrows site, the uniformity of distribution of fertilizer-N applied through fertigation was satisfactory, which was achieved both at distance (600 m) and depth (0-600 mm). Applying fertilizer-N through fertigation, at the rate used in this study, showed relatively small (<= 8%) improvements in cotton yield, which was explained by relatively high N rates (180 kg ha(-1) N) applied before planting. Given current price ratios (fertilizer-to-cotton), application of N through fertigation appears to be economical in both systems, but relative agronomic efficiencies and economic return from the fertilizer applied were lower in furrow compared with overhead (P<0.05). Fertigation may be recommended when pre-season N application rates are low (e.g., <100 kg ha(-1) N), particularly in overhead irrigation as significantly higher efficiencies both in terms of water and N use can be achieved with this system. This would enable some of the operational constraints associated with application of N in-crop season to be overcome; thereby, reducing the need for high rates of N applied up-front. For the overhead system, there were also advantages compared with the furrow system in terms of reduced potential for N2O emissions after irrigation or fertigation. Overall, short-term (30-day period) soil emissions of N2O were approximately eight times higher in furrow compared with overhead. Emissions from non-fertigated crops were approximately two times higher in furrow compared with overhead. Emissions from the fertigated crop under the overhead system were comparable to the non-fertigated crop of the furrow system (P>0.05). In both systems, fluxes were highest within five days of irrigation or fertigation, but they decreased significantly after that time as soil moisture content (water-filled pore space) and soil nitrate levels decreased due to crop uptake. Nitrous oxide fluxes were similar in furrow and overhead 15 days after the irrigation or fertigation event. Areas that warrant further investigation are presented and discussed, including the need for improved timing of fertilizer delivery during the irrigation cycle to ensure that N losses through leaching or gaseous evolution (e.g., N2O, N-2) are not economically or environmentally significant.

Abstract  Unsymmetrical dimethylhydrazine (UDMH) is a high N-containing (as much as nearly 50%) substance. Traditional treatment methods such as incineration will inevitably cause the formation of nitric oxide and secondary pollution. Supercritical water is a preferred transformation medium due to its unique physicochemical properties. However, at present most of studies are limited to supercritical water oxidation (SCWO) which tends to produce hydrogen nitrate resulting in corrosion to the reactor. To conquer this problem, we propose supercritical water gasification (SCWG) technology which is in a reducing environment, realizing both harmless treatment and resource utilization. In order to promote its industrialization process, the reaction pathways and kinetic parameters should be studied. In this paper, the reaction pathways and kinetics of UDMH in supercritical water were conducted under the conditions of 400 C-degrees-550 C-degrees in quartz reactor, which avoids the catalytic effect on the reaction kinetics. From the resource utilization perspective, the most abundant quantitatively detectable gaseous product is methane, together with less hydrogen, carbon monoxide and ethane orderly. All these gaseous products are combustible. The maximum of carbon efficiency is 90.25% at 550 C-degrees, 10 min. In the point of view of harmless treatment, the organic compounds contained in the residual liquid are detected with H-1 NMR, FTIR and GC/MS. Results show that UDMH could be fully degraded within 3 min and the ultimate organic compounds in the residual liquid are mainly dimethylamino acetonitrile and trimethylamine. In addition, a reaction pathway for UDMH disposed in supercritical water is developed. Finally, the quantitative kinetic model for describing the gaseous products and ammonia-nitrogen in the residual liquid is brought forward. The pyrolysis activation energy for UDMH in supercritical water is 49.98 +/- 7.38 kJ/mol. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Abstract  Poly(acrylamide) (PAAM) was grafted onto crosslinked poly(hydroxy ethyl methacrylate) (HEMA)-based beads for the removal of phenol from aqueous solution. A beaded polymer with a PAAM surface shell was prepared in two steps: synthesis of crosslinked poly (HEMA (50% mol) - MMA (40% mol) - EGDMA (10% mol)) terpolymers spherical beads (200-420 mu m) (resin 1) via the suspension polymerization method; and the grafting of PAAM was carried out by redox initiation from hydroxyl groups on resin1 by using cerium (IV) ammonium nitrate as the initiator.The resulting polymeric sorbent (resin 2) with about 82 wt.% grafted PAAM has been demonstrated to be efficient to remove phenol from water. Moreover, phenol sorption capacities of resin 1 and resin 2 were compared and sorption experiments were performed depending on the initial phenol concentration and pH. Kinetic measurements and models were studied for resin 1 and resin 2.

Abstract  Large-scale agricultural land reclamation activities can trigger substantial changes in the soil bacterial community by disturbances associated with growth of crops and addition of fertilizers and pesticides. In this study, the bacterial 16S gene was sequenced on the Illumina MiSeq platform for bacterial identification and taxonomy. We investigated the (i) soil bacterial diversity and community composition in natural marsh, moderate and severe intensity of interference in wetlands, and (ii) the relationship between soil physical and chemical properties, and soil bacterial community structures in order to understand the effects of interference intensities on the marsh soil environment in the Sanjiang Plain wetland, Northeast China. The natural marsh soil contained most of 573 operational taxonomic units (OTUs) between all the three sites (n=1241), while wetland soils of moderate and severe intensity of interference had only 510 and 401 OTUs, respectively. The soil bacterial diversity and richness indices of all disturbed wetlands presented a decline at the OTU level, alpha diversity (Shannon diversity and Chao and Ace diversities). In addition, the composition of soil bacterial communities showed different trends and structure after the disturbance. There were significant variation in unclassified genera and some dominant genera (relative abundance>1% in at least one site) between natural marsh and difference in interference intensities in disturbed wetlands, including Acidobacteria, Proteobacteria, Verrucomicrobia, Actinobacteria, Chlorobi and Gemmatimonadetes. Composition of soil bacterial community was affected by Soil Moisture, pH, Soil Organic Carbon, Total Nitrogen, Available Nitrogen, Total Phosphorus, Available Phosphorus, Total Potassium, Nitrate Nitrogen, Available Potassium and Ammonium Nitrogen. This study will provide a fundamental scope to understand the bacterial community structure in wetland ecosystems and the environmental function as a predictor of bacterial community composition. (C) 2018 Friends Science Publishers