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Nitrous acid (HONO) is an important radical precursor that can impact secondary pollutant levels, especially in urban environments. Due to uncertainties in its heterogeneous formation mechanisms, models often under predict HONO concentrations. A number of heterogeneous sources at the ground have been proposed but there is no consensus about which play a significant role in the urban boundary layer. We present a new one‐dimensional chemistry and transport model which performs surface chemistry based on molecular collisions and chemical conversion, allowing us to add detailed HONO formation chemistry at the ground. We conducted model runs for the 2010 CalNex campaign, finding good agreement with observations for key species such as O3, NOx, and HOx. With the ground sources implemented, the model captures the diurnal and vertical profile of the HONO observations. Primary HOx production from HONO photolysis is 2–3 times more important than O3 or HCHO photolysis at mid‐day, below 10 m. The HONO concentration, and its contribution to HOx, decreases quickly with altitude. Heterogeneous chemistry at the ground provided a HONO source of 2.5 × 1011 molecules cm−2 s−1 during the day and 5 × 1010 molecules cm−2 s−1 at night. The night time source was dominated by NO2 hydrolysis. During the day, photolysis of surface HNO3/nitrate contributed 45%–60% and photo‐enhanced conversion of NO2 contributed 20%–45%. Sensitivity studies addressing the uncertainties in both photolytic mechanisms show that, while the relative contribution of either source can vary, HNO3/nitrate is required to produce a surface HONO source that is strong enough to explain observations. Key Points: Measured vertical profiles of HONO near Los Angeles in May 2010 suggest a heterogeneous HONO source at the groundA new 1D chemistry and transport model that includes HONO formation on the ground reproduces the HONO concentration profilesThe main daytime HONO source is adsorbed nitric acid/nitrate photolysis, followed by photo‐enhanced NO2 conversion [ABSTRACT FROM AUTHOR]

The relative importance of char-N and volatile-N on NOx emissions is examined in a pilot-scale fluidized-bed combustor. Coke and toluene are used as the base fuels, and nitrogenous compounds (nitrobenzene, pyridine, and pyrrole) are mixed with them alternatively to study the effect of nitrogen origin on NOx formation and reduction. The results show that NOx evolution would be greatly changed if the nitrogenous species are present in the volatile, and NOx reduction inside the combustor may be the key factor that determines the final emissions. When nitrobenzene is employed, the conversion of volatile-N to NOx is 13.17–15.42%, while that of char-N is 4.49–7.59% in the bed temperature of 750–900 °C, indicating that nitrogen present in volatiles may be much more prone to elicit higher NOx. Moreover, the volatile-N conversion to NOx is always greater than that of char-N, regardless of the nitrogen functionality. However, the degree of formation and reduction of NOx would depend firmly on the functional groups of nitrogen, which are nitro, pyridine, and pyrrole in this case. NOx reduction mainly occurs in the splash zone, and NOx generated from char-N is reduced in a manner dissimilar to that of volatile-N. [ABSTRACT FROM AUTHOR]

This study aimed to develop methods for assessing and identifying nitrogen sources in the Cheongmi River, Korea, that has intensive livestock farming areas (ILFA) in its watershed. The assessment focused on the feasibility of the simultaneous use of stable isotopic compositions of ammonium (δ15NNH4) and nitrate (δ15NNO3) for identifying the main nitrogen pollution sources in the Cheongmi River watershed. Our results suggested that the organic nitrogen (Org-N) to total nitrogen (T-N) ratio could be used as an indicator for assessing the effect of livestock excreta on waterways in ILFA. We observed that the T-N concentration was much more strongly affected by livestock excreta than the T-P concentration in the mainstream of the Cheongmi River. The positive correlation was more significant between δ15NNH4 and NH4-N than that between δ15NNO3 and NO3-N for river water samples. Furthermore, the use of δ15NNH4 was more effective than that of δ15NNO3 in evaluating nitrogen variations between May and August in the Cheongmi River because the differences in δ15NNH4 between May and August were more remarkable compared to those in δ15NNO3. Finally, the simultaneous use of δ15NNH4 and δ15NNO3 showed that the dominant nitrogen source at sites M3, M4, M5, and M6, specifically in May, was livestock excreta in the Cheongmi River. The results of this study could be used for sustainable water quality management in the Cheongmi River watershed. [ABSTRACT FROM AUTHOR]

Understanding which factors affect the algal bioavailability of dissolved organic nitrogen (DON) compounds in natural surface waters is important for our understanding of nutrient biogeochemistry and water quality management. We used nitrogen uptake kinetics and algal cell yield to characterize the algal bioavailability of 22 dissolved DON compounds that are commonly found in natural surface waters and wastewater treatment plant effluents, including urea, amino acids, amino sugars, nucleotides, pyrimidines, oraganonitriles, polyacrylamide, EDTA, caffeine, phenolic compounds and humic acids. Twelve of these compounds were highly bioavailable, including urea, dissolved free amino acids, bovine serum albumin, DNA, RNA, ATP, AMP, acetonitrile and caffeine. Four compounds had intermediate bioavailability including two humic acids (Elliott Soil and Pahokee Peat), glycylglycine, RNA and uracil. The remaining six compounds were classified as recalcitrant, i.e., EDTA, 2,3-Dinitrophenol, aminobenzoic acid, polyacrylamide and Aldrich humic acid. For many of the compounds tested, the algal cell yield was only 60–80% of expected relative to DON uptake. These results help explain why some DON compounds are more likely to persist in natural systems, and why the DON pool is often recalcitrant in surface waters. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The combined use of methods of passive dosimetry of the status of atmospheric air, phytoindication, and cartographic visualization of data made it possible to elaborate and substantiate approaches to evaluation of the effect of atmospheric air contamination on the eutrophication of forest ecosystems under urban conditions. [ABSTRACT FROM AUTHOR]

Nitrogenous gaseous emissions commonly have an obnoxious odor associated with it, which when discharged into the environment results in serious environmental problems and health hazards. Several strategies for mitigation of nitrogenous odorants have been reported which include physical, chemical and biological methods. Biological treatments are widely employed because of their efficiency even at low concentration, where physical and chemical methods are not effective. Most commonly used biological treatment methods are biofiltration, biotrickling filters and membrane bioreactors with innovative reactor design, mixing pattern, and air sparging, for example FEBR, ALR, etc. These treatment methods require a critical assessment for the mitigation of obnoxious nitrogen emissions, especially in the context of environmental protection. This review offers a critical evaluation of treatment methods for the mitigation of nitrogenous odorous compound with a key emphasis on biological treatment systems. Also, various mathematical modelling techniques required for optimized operation of biotreatment systems has been discussed. [ABSTRACT FROM AUTHOR]

It has been found that the total productivity of bacteria and micromycetes in the 0- to 50-cm layer of homogeneous cryozems (Cryosols) on slopes of northern and southern exposures varies from 1.2 to 1.4 t/ha, respectively, and the calculated content of microbial carbon varies in the range 0.7-0.9 t/ha. The respiratory activity of the upper soil layer is 2.5-2.6 μg C-CO/(g h); the potential methane formation capacity reaches 0.13 nmol CH/(m day) for soils on slopes of northern exposure and 0.16 nmol CH/(m day) for slopes of southern exposure. Accumulation of sorbed ammonium is recorded in the range 15-17 mg NH/100 g soil in summer. The increase of temperature in the upper horizons of soils on slopes of southern exposure by 5°C compared to the northern slopes results in only an insignificant increase in the emission of CO and CH. The accumulation of sorbed ammonium and nitrate nitrogen in homogeneous cryozems during the vegetation period is comparable to that in gray forest soils of the southern taiga subzone of the Middle Siberia. [ABSTRACT FROM AUTHOR]

We assessed the rainwater chemistry, the potential sources of its main inorganic components and bulk atmospheric deposition in a rural tropical semiarid region in the Brazilian Caatinga. Rainfall samples were collected during two wet seasons, one during an extremely dry year (2012) and one during a year with normal rainfall (2013). According to measurements of the main inorganic ions in the rainwater (H, Na, NH , K, Ca, Mg, Cl, NO , and SO ), no differences were observed in the total ionic charge between the two investigated wet seasons. However, Ca, K, NH and NO were significant higher in the wetter year ( p < 0.05) which was attributed to anthropogenic activities, such as organic fertilizer applications. The total ionic contents of the rainwater suggested a dominant marine contribution, accounting for 76 % and 58 % of the rainwater in 2012 and 2013, respectively. The sum of the non-sea-salt fractions of Cl, SO , Mg, Ca and K were 19 % and 33 % in 2012 and 2013, and the nitrogenous compounds accounted for 2.8 % and 6.0 % of the total ionic contents in 2012 and 2013, respectively. The ionic ratios suggested that Mg was probably the main neutralizing constituent of rainwater acidity, followed by Ca. We observed a low bulk atmospheric deposition of all major rainwater ions during both wet seasons. Regarding nitrogen deposition, we estimated slightly lower annual inputs than previous global estimates. Our findings contribute to the understanding of rainfall chemistry in northeastern Brazil by providing baseline information for a previously unstudied tropical semiarid ecosystem. [ABSTRACT FROM AUTHOR]

Copyright of Inzynieria Mineralna is the property of Polskie Towarzystwo Przerobki Kopalin and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A series of novel soluble phthalazinone-based copoly(aryl ether nitrile)s (PPBENs) were successfully synthesized by the nucleophilic substitution reaction of 2,6-difluorobenzonitrile (DFBN) with varying mole proportions of 4-(4-hydroxylphenyl)-2,3-phthalazin-1(2H)-one (DHPZ) and 4,4′-dihydroxybiphenyl (BP). These obtained copolymers had inherent viscosities between 0.88 and 1.26 dL/g in N-methyl-2-pyrrolidone (NMP) at a concentration of 0.5 g dL at 25 °C. Most of the obtained copolymers were soluble in common polar aprotic solvents, involving NMP, DMF, DMAc and chloroform, etc., at room temperature. The glass transition temperature was found to increase with increasing the DHPZ unit concentration in the copolymer main chain, ranging from 222 to 286 °C. Thermal gravimetric analysis showed that all the copolymers had 5 % weight loss temperature up to 521 °C and the high char yield above 65 % at 800 °C in nitrogen atmosphere. PPBEN2 exhibited the best mechanical properties which were measured using film samples. Its tensile strength and elongation at break were up to 137 MPa and 15 %, respectively. The thermal degradation process of PPBENs was discussed using thermogravimetric analysis (TGA) and FTIR. The apparent activation energy values were 273.5 and 274.1 kJ/mol which were calculated by Kissinger-Akahira-Sunose method and Flynn-Wall-Ozawa method, respectively. The results showed that the obtained copolymers possess excellent thermooxidation. [ABSTRACT FROM AUTHOR]

This report describes the development of an analytical methodology on microchip electrophoresis (ME) devices coupled with capacitively coupled contactless conductivity detection (C 4 D) to monitor inorganic anions in environmental samples. The buffer composition as well as detection operating parameters were optimized to achieve the best separation selectivity and detector sensitivity, respectively. Electrophoretic separations of Cl − , NO 3 − , SO 4 2− and NO 2 − were successfully performed within 60 s using a running buffer composed of 30 mmol L −1 latic acid and 15 mmol L −1 l -histidine (His). The best detectability levels were found applying a sinusoidal wave with 1100-kHz-frequency and 60- V pp amplitude. Quantitative analyzes of inorganic anions were carried out in the presence of Cr 2 O 7 2− ion as internal standard (IS), which ensured great repeatability in terms of migration times (<1%) and peak areas (6.2–7.6%) for thirty consecutive injections. The analytical performance revealed a linear behavior for concentration ranges between 0–120 μmol L −1 (Cl − , NO 2 − and NO 3 − ) and 0–60 μmol L −1 (SO 4 2− ) and limits of detection (LODs) varying from 2.0 to 4.9 μmol L −1 . The concentration levels of anionic species were determined in aquarium, river and biofertilizer samples with recovery values between 91% and 105%. The nitrification steps associated with conversion of ammonium to nitrite followed by the conversion of nitrite to nitrate were successfully monitored in a simulated environment without fishes during a period of twelve weeks. Lastly, the monitoring of anionic species was carried out during eight weeks in an aquarium environment containing ten fishes from Danio rerio (Ciprynidae) . The recorded data revealed the absence of nitrite and a gradual increase on the ammonium and nitrate concentration levels during eight weeks, thus suggesting the direct conversion of ammonium to nitrate. Based on the data herein reported, the proposed analytical methodology can be used for routine environmental analysis. [ABSTRACT FROM AUTHOR]

The removal of nitrogen compounds (N-compounds) from fuels has attracted considerable attention because of the necessity to reduce nitrogen oxide emission and improve sulfur elimination. In this work, we reported a novel denitrogenation method of fuels using deep eutectic solvents (DESs) as extractants, and demonstrated the essential role of a rational control of the physicochemical character of DESs in achieving superior denitrogenation performance. Among the investigated DESs, the 1 : 2 molar mixture of choline chloride and phenylacetic acid presented the best denitrogenation performance, showing simultaneous efficient removal of both basic and non-basic N-compounds. Without chemical reactions, the extraction efficiencies of pyridine and carbazole at 308 K with a 1 : 1 DES : oil mass ratio were 99.2% and 98.2%, respectively, and the selectivities to n-heptane were higher than 10 000. This was better than the performance of compared conventional solvents. The extraction efficiency was not sensitive to the DES : oil mass ratio and temperature, and remained unchanged after four regeneration cycles. In addition to the “green solvents” character of DESs, these results collectively demonstrate the considerable potential of DESs as promising materials for the green and efficient denitrogenation of fuels. [ABSTRACT FROM AUTHOR]

Tracing pollution sources and transformation of nitrogen compounds in surface- and groundwater is an issue of great significance worldwide due to the increased human activity, translated in high demand of water resources and pollution. In this work, the hydrological basin of an important chemical industrial platform in Romania (Ramnicu Valcea industrial area) was characterized in terms of the physico-chemical and isotope composition of δ 18 O and δ 2 H in water samples and δ 15 N of the inorganic nitrogen species. Throughout a period of one year, water samples from the Olt River and its more important tributaries were collected monthly in the industrial area, when the seasonal and spatial isotope patterns of the surface waters and the main sources of pollution were determined. Higher inorganic nitrogen concentrations (up to 10.2 mg N L − 1 ) were measured between November 2012 and April 2013, which were designated as anthropogenic additions using the mixing calculations. The main sources of pollution with inorganic nitrogen were agriculture and residential release. The inorganic nitrogen from the industrial waste water duct had a distinct δ 15 N fingerprint (mean of − 8.6‰). Also, one industrial release into the environment was identified for Olt River, at Ionesti site, in November 2012. The mean precipitation samples had the lowest inorganic nitrogen concentrations (less than 5.5 mg N L − 1 ) with a distinct δ 15 N fingerprint compared to the surface and industrial waters. [ABSTRACT FROM AUTHOR]

A subsurface nitrite maximum was observed along one transection near the Xisha Islands in the South China Sea in early September 2009. Possible causes were examined using in situ observed data and remote sensing data. A cold eddy was identified near the Xisha Islands during the periods of study. The Xisha Islands' water receives copious supplies of nutrients through cold eddies. Accumulation of nitrite about 50 m deep reaches 0.49 μmol l−1, and forms and maintains the primary nitrite maximum. The relationship between NO2−and Chl-ais very significant (R2= 0.5829, p-value(statistical significance)= 0.00). Nitrification processes would result in apparent oxygen utilization (AOU) ranging from 0.22 to 35.88 μM, around 24.60% of the total biological oxygen demand in the water column of under-saturation of dissolved oxygen. This value is very close to the Redfield stoichiometry (32/138 = 23%) of total oxygen consumption associated with organic matter diagenesis. These results may support the hypothesis that phytoplankton and the nitrification process have an important influence on the PNM or 260 maintenance in the euphotic layer. Our results indicate that physical conditions and biological activities near the Xisha Islands play a significant role in regulating biogeochemistry. [ABSTRACT FROM PUBLISHER]

Controlled tile drainage (CTD) regulates water and nutrient export from tile drainage systems. Observations of the effects of CTD imposed en masse at watershed scales are needed to determine the effect on downstream receptors. A paired-watershed approach was used to evaluate the effect of field-to-field CTD at the watershed scale on fluxes and flow-weighted mean concentrations (FWMCs) of N and P during multiple growing seasons. One watershed (467-ha catchment area) was under CTD management (treatment [CTD] watershed); the other (250-ha catchment area) had freely draining or uncontrolled tile drainage (UCTD) (reference [UCTD] watershed). The paired agricultural watersheds are located in eastern Ontario, Canada. Analysis of covariance and paired t tests were used to assess daily fluxes and FWMCs during a calibration period when CTD intervention on the treatment watershed was minimal (2005-2006, when only 4-10% of the tile-drained area was under CTD) and a treatment period when the treatment (CTD) watershed had prolific CTD intervention (2007-2011 when 82% of tile drained fields were controlled, occupying >70% of catchment area). Significant linear regression slope changes assessed using ANCOVA (p ≤ 0.1) for daily fluxes from upstream and downstream monitoring sites pooled by calibration and treatment period were -0.06 and -0.20 (stream water) (negative values represent flux declines in CTD watershed), -0.59 and -0.77 (NH4+-N), -0.14 and -0.15 (NO3--N), -1.77 and -2.10 (dissolved reactive P), and -0.28 and 0.45 (total P). Total P results for one site comparison contrasted with other findings likely due to unknown in-stream processes affecting total P loading, not efficacy of CTD. The FWMC results were mixed and inconclusive but suggest physical abatement by CTD is the means by which nutrient fluxes are predominantly reduced at these scales. Overall, our study results indicate that CTD is an effective practice for reducing watershed scale fluxes of stream water, N, and P during the growing season. [ABSTRACT FROM AUTHOR]

Autotrophic denitrification with sulphide using nitrate (R1) and nitrite (R2) as electron acceptor was investigated at bench scale. Different solids retention times (SRT) (5 and 20 d) have been tested in R1 while R2 was operated at SRT= 13 d. The results indicated that the process allows complete sulphide removal to be achieved in all tested conditions. Tested sulphide loads were estimated from the H2S produced in a pilot-scale anaerobic digester treating vegetable tannery primary sludge; nitrogen loads originated from the nitrification of the supernatant. Average nitrogen removal efficiencies higher than 80% were observed in all the tested conditions once steady state was reached. A maximum specific nitrate removal rate equal to 0.35 g N-NO3- g VSS-1 d-1 was reached in R1. Due to sulphide limitation, incomplete denitrification was observed and nitrite and thiosulphate tend to accumulate especially in the presence of variable environmental conditions in both R1 and R2. Lower SRT caused higher NO2 accumulated/NO3reduced ratios (0.22 and 0.24, with SRT of 5 d and 20 d, respectively) using nitrate as electron acceptor in steady-state condition. Temperature decrease caused sudden NO2accumulated/NO3reduced ratio increase in R1 and NO2- removal decrease in R2. [ABSTRACT FROM AUTHOR]

Reactive Nitrogen is critical in the global food system because of its role in soil fertility, but it has detrimental effects on the environment, human health and the economy. This article explores why, unlike other environmental issues, discussion of nitrogen pollution has not been picked up by the NGO community. It draws on existing research crosscutting environment, economics, public health, and environmental politics as well as relevant social sciences literature in agenda setting and framing. It concludes that the combined effects of the complex nature of the environmental problem; communication challenges; geographic focus; fatigue for "new" environmental programmes; and a challenging political environment make the nitrogen challenge particularly difficult to incorporate into NGO programming. With a burgeoning global population and growing pressure from other environmental stresses, nitrogen management will become increasingly critical to NGO work. [ABSTRACT FROM AUTHOR]

Nitrogen (N) deposition in China has been dramatically enhanced by anthropogenic emissions and has aroused great concerns of its impacts on forest ecosystems. This study synthesized data on ammonium (NH 4 + ) and nitrate (NO 3 − ) contents in bulk precipitation and throughfall from 38 forest stands in published literature to assess the status and characteristics of N deposition to typical forests in China between 1995 and 2010. Our results showed that ammonium dominated N deposition in this period, with a mean NH 4 + –N:NO 3 − –N ratio of ∼2.5 in bulk deposition and throughfall. Mean throughfall N deposition in China's forests was as high as 14.0 kg N ha −1 yr −1 for ammonium, 5.5 kg N ha −1 yr −1 for nitrate and 21.5 kg N ha −1 yr −1 for total inorganic N (TIN), respectively. Mean bulk deposition was 9.4 kg N ha −1 yr −1 for ammonium, 3.9 kg N ha −1 yr −1 for nitrate and 14.0 kg N ha −1 yr −1 for TIN, respectively. Canopy captured dry deposition, calculated as the difference between throughfall and bulk deposition, was thus approximately half of the bulk deposition. Spatial patterns of N deposition were in accordance with our urban hotspot hypothesis, showing a strong power-law reduction of ammonium with increasing distance to large cities but only slightly lower nitrate deposition. Our results suggest that high N deposition, especially of ammonium, exceeds critical N loads for large areas of China's forests. [ABSTRACT FROM AUTHOR]

Nitrate leaching (NL) is a major concern in agriculture due to its impact on human health and ecosystems. Solute movement through soil is governed by various hydraulic and physical properties that determine water flow. To study such relationships, a pedotransfer function of groundwater pollution was developed in two alluvial irrigated soils under long-term pig slurry applications. Two basins of central Chile, San Pedro (Typic Xerochrepts) and Pichidegua (Mollic Xerofluvents) were selected, where maize (Zea mays L.) was grown in spring-summer, while during autumn-winter period a ryegrass-barley-oat mixed crop was established in San Pedro and a fallow management applied in Pichidegua. Soils in cultivated and control sites were characterized in physical and hydraulic terms. Nitrogen and water budgets were determined measuring periodically (biweekly) N concentration (N-NC3- and N-NH4+) and monitoring water contents in soil profiles, respectively. Dye tracer tests were performed with brilliant blue (BB) dye and the staining patterns analyzed. To contrast the effect of slurry additions over soil physical properties and over NL, r-Student tests were performed. Some accurate pollution groundwater NL pedotransfer functions were obtained calculated through least square fit models and artificial neural networks. Textural porosity, mean diameter variation, slow drainage porosity, air conductivity at 33 kPa water tension and N-NO3- concentrations were directly related to NL. In terms of preferential flow analysis, stained path width > 200 mm was inversely associated to NL. Finally, dye tracer tests provided a better understanding of the characteristics and pattern of water/solute movement through soil to groundwater. [ABSTRACT FROM AUTHOR]

Abstract: Global climate models predict that future environmental conditions will see alterations in temperature, water availability and CO2 concentration ([CO2]) in the atmosphere. Climate change will reinforce the need to develop highly productive crops. For this purpose it is essential to identify target traits conditioning plant performance in changing environments. N2 fixing plants represent the second major crop of agricultural importance worldwide. The current review provides a compilation of results from existing literature on the effects of several abiotic stress conditions on nodule performance and N2 fixation. The environmental factors analysed include water stress, salinity, temperature, and elevated [CO2]. Despite the large number of studies analysing [CO2] effects in plants, frequently they have been conducted under optimal growth conditions that are difficult to find in natural conditions where different stresses often occur simultaneously. This is why we have also included a section describing the current state of knowledge of interacting environmental conditions in nodule functioning. Regardless of the environmental factor considered, it is evident that some general patterns of nodule response are observed. Nodule carbohydrate and N compound availability, together with the presence of oxygen reactive species (ROS) have proven to be the key factors modulating N2 fixation at the physiological/biochemical levels. However, with the exception of water availability and [CO2], it should also be considered that nodule performance has not been characterised in detail under other limiting growth conditions. This highlights the necessity to conduct further studies considering these factors. Finally, we also observe that a better understanding of these metabolic effects of changing environment in nodule functioning would require an integrated and synergistic investigation based on widely used and novel protocols such as transcriptomics, proteomics, metabolomics and stable isotopes. [Copyright &y& Elsevier]

Abstract: Citizen science is having increasing influence on environmental monitoring as its advantages are becoming recognised. However methodologies are often simplified to make them accessible to citizen scientists. We tested whether a recent citizen science survey (the OPAL Air Survey) could detect trends in lichen community composition over transects away from roads. We hypothesised that the abundance of nitrophilic lichens would decrease with distance from the road, while that of nitrophobic lichens would increase. The hypothesised changes were detected along strong pollution gradients, but not where the road source was relatively weak, or background pollution relatively high. We conclude that the simplified OPAL methodology can detect large contrasts in nitrogenous pollution, but it may not be able to detect more subtle changes in pollution exposure. Similar studies are needed in conjunction with the ever-growing body of citizen science work to ensure that the limitations of these methods are fully understood. [Copyright &y& Elsevier]

Ammonia is a metabolite of aquatic organisms which might reach deleterious levels in intensive fish farms. The aim of the present study was to determine median lethal concentrations (96-h LC50) of total ammonia nitrogen ( TA-N) on marbled spinefoot rabbitfish ( Siganus rivulatus) and chronic effects of TA-N on survival, growth and behaviour of juvenile rabbitfish over a 50 day period. In the first experiment, fish were exposed to 0, 2, 4, 6, 8, 10, 12, 14, 16, 18 and 20 mg L−1 TA-N for 96 h and survival evaluated. In the second experiment, 12 fish were stocked per 50-L tank and treated with one of 0, 2, 4, 6, 8, 10 and 12 mg L−1 TA-N with three replicate tanks per treatment. Survival and growth were determined and histopathological alterations of gills due to chronic ammonia exposure were studied by light and electron microscopy. The 96-h LC50 values were 16-18 mg L−1 TA-N. In the chronic exposure experiment, fish reared in water with 0 mg L−1 TA-N had 100% survival and had 50% weight increase in 50 days. Fish at 2 and 4 mg L−1 TA-N all died whilst fish in 6, 8, 10 and 12 mg L−1 TA-N survived and grew albeit less than in treatment 0 mg L−1. Gills from ammonia treated fish displayed severe histological and ultrastructural alterations including hyperplasia, hypertrophy and fusion of secondary lamellae, aneurysms and presence of pleomorphic altered cells. Chronic exposure to ammonia is deleterious to marbled spinefoot rabbitfish and low concentrations of ammonia appear to kill the fish in <50 days whilst fish can survive for more than 50 days at concentrations between 6 and 12 mg L−1 TA-N. [ABSTRACT FROM AUTHOR]

Nitrogen deposition is a concern in many protected ecosystems around the world, yet few studies have quantified a complete reactive nitrogen deposition budget including all dry and wet, inorganic and organic compounds. Critical loads that identify the level at which nitrogen deposition negatively affects an ecosystem are often defined using incomplete reactive nitrogen budgets. Frequently only wet deposition of ammonium and nitrate are considered, despite the importance of other nitrogen deposition pathways. Recently, dry deposition pathways including particulate ammonium and nitrate and gas phase nitric acid have been added to nitrogen deposition budgets. However, other nitrogen deposition pathways, including dry deposition of ammonia and wet deposition of organic nitrogen, still are rarely included. In this study, a more complete seasonal nitrogen deposition budget was constructed based on observations during a year-long study period from November 2008 to November 2009 at a location on the east side of Rocky Mountain National Park (RMNP), Colorado, USA. Measurements included wet deposition of ammonium, nitrate, and organic nitrogen, PM2.5 (particulate matter with an aerodynamic diameter less than 2.5 lm, nitrate, and ammonium) concentrations of ammonium, nitrate, and organic nitrogen, and atmospheric gas phase concentrations of ammonia, nitric acid, and NO2. Dry deposition fluxes were determined from measured ambient concentrations and modeled deposition velocities. Total reactive nitrogen deposition by all included pathways was found to be 3.65 kg N·ha-11yr-11. Monthly deposition fluxes ranged from 0.06 to 0.54 kg N·ha-11yr-11, with peak deposition in the month of July and the least deposition in December. Wet deposition of ammonium and nitrate were the two largest deposition pathways, together contributing 1.97 kg N·ha-11yr-11 or 54% of the total nitrogen deposition budget for this region. The next two largest deposition pathways were wet deposition of organic nitrogen and dry deposition of ammonia; combined they contributed 1.37 kg N·ha-11yr-11 or 37% of the total nitrogen deposition budget. To better understand the nitrogen cycle and key interactions between the atmosphere and biosphere we need to include as many sources and types of nitrogen as possible and understand their variability throughout the year. Here we examine the components of the nitrogen deposition budget to better understand the factors that influence the different deposition pathways and their seasonal variations. [ABSTRACT FROM AUTHOR]

This study investigated the physiological response of the epiphytic lichen Evernia prunastri to ecologically relevant concentrations of nitrogen compounds. Lichen samples were sprayed for 4 weeks either with water or 50, 150 and 500 μM NH4Cl. The integrity of cell membranes and chlorophyll a fluorescence emission (F V/F M and PIABS) were analyzed. No membrane damage occurred after the exposure period. F V/F M, a classical fluorescence indicator, decreased during the second week of treatment with 500 μM NH4Cl and the third week with 50 and 150 μM NH4Cl. PIABS, an overall index of the photosynthetic performance, was more sensitive and decreased already during the first week with 500 μM NH4Cl and the second week with 150 μM NH4Cl. Since E. prunastri has been exposed to ammonium loads corresponding to real environmental conditions, these findings open the way to an effective use of this species as early indicators of environmental nitrogen excess. [Copyright &y& Elsevier]

Reactive nitrogen (Nr) compounds have different fates in the atmosphere due to differences in the governing processes of physical transport, deposition and chemical transformation. Nr compounds addressed here include reduced nitrogen (NHx: ammonia (NH3) and its reaction product ammonium (NH4+)), oxidized nitrogen (NOy: nitrogen monoxide (NO) + nitrogen dioxide (NO2) and their reaction products) as well as organic nitrogen compounds (organic N). Pollution abatement strategies need to take into account the differences in the governing processes of these compounds when assessing their impact on ecosystem services, biodiversity, human health and climate. NOx (NO+NO2) emitted from traffic affects human health in urban areas where the presence of buildings increases the residence time in streets. In urban areas this leads to enhanced exposure of the population to NOx concentrations. NOx emissions generally have little impact on nearby ecosystems because of the small dry deposition rates of NOx. These compounds need to be converted into nitric acid (HNO3) before removal through deposition is efficient. HNO3 sticks quickly to any surface and is thereby either dry deposited or incorporated into aerosols as nitrate (NO3-). In contrast to NOx compounds, NH3 has potentially high impacts on ecosystems near the main agricultural sources of NH3 because of its large ground-level concentrations along with large dry deposition rates. Aerosol phase NH4+). and NO3-). contribute significantly to background PM2.5 and PM10 (mass of aerosols with an aerodynamic diameter of less than 2.5 and 10 µm, respectively) with an impact on radiation balance as well as potentially on human health. Little is known quantitatively and qualitatively about organic N in the atmosphere, other than that it contributes a significant fraction of wet-deposited N, and is present in both gaseous and particulate forms. Further studies are needed to characterise the sources, air chemistry and removal rates of organic N emissions. [ABSTRACT FROM AUTHOR]

Nitrogenous air pollutants including nitrogen dioxide (NO), nitric acid (HNO), nitrate (NO), ammonia (NH), ammonium (NH), and nitrous acid (HONO) were characterized at an urban forested (UF) site in Hiroshima and at a suburban forested (SF) site in Fukuoka, western Japan, using an annular denuder system for 1 year from May 2006 to May 2007 to compare the concentrations and chemical species of atmospheric nitrogenous pollutants between UF and SF sites. The proximity of the urban area was reflected in higher NO concentrations at the UF site than at the SF site. NO was more oxidized at the SF site because it is farther from an urban area than the UF site, which was reflected in higher concentrations of HNO at the SF site than the UF site. HNO and acidic sulfate is neutralized by NH, existing as ammonium nitrate (NHNO) and ammonium sulfate [(NH)SO] at the UF site. At the SF site, acidic sulfate is neutralized by NH, existing as (NH)SO, but NHNO, had scarcely formed at the SF site. A much higher HONO concentration was observed at the UF site than at the SF site, especially in winter and spring at night, which could be explained by higher NO concentrations at the UF site because of its proximity to an urban area and stagnant meteorological conditions. Atmospheric HONO determination was critical in evaluating the possibility of damage to trees in UF areas. [ABSTRACT FROM AUTHOR]

In this study, a consistent basin-wise monthly time series of the atmospheric nutrient load to the Baltic Sea during 1850-2006 was compiled. Due to the lack of a long time series (1850-1960) of nutrient deposition to the Baltic Sea, the data set was compiled by combining a time series of deposition data at the Baltic Nest Institute from 1970 to 2006, published historical monitoring data and deposition estimates, as well as recent modeled Representative Concentration Pathways (RCP) emission estimates. The procedure for nitrogen compounds included estimation of the deposition in a few intermediate reference years, linear interpolation between them, and the decomposition of annual deposition into a seasonal deposition pattern. As no reliable monitoring results were found for the atmospheric deposition of phosphorus during the early period of our study, we used published estimates for the temporal and spatial pattern of the phosphorus load. [ABSTRACT FROM AUTHOR]

Abstract: Amine reclaimer wastes (ARW) generated in CO2 capture processes demand suitable disposal means. Such wastes contain remaining amine, NH3 and other degradation compounds. This study investigated the potential of using ARW as a NO x reducing agent, under laboratory conditions in a flow reactor. A simulated flue gas containing about 500ppm of NO and 5% O2 was injected with liquid ARW under different stoichiometric ratios (TN/NO – total N to nitric oxide ratio) and temperatures. The ARW was obtained from a distillation monoethanolamine reclaimer in an industrial CO2 capture facility with a coal fired boiler. The results indicate that ARW has a significant NO x reduction potential when injected with TN/NO ratios in excess of 1. The optimum temperature is close to 950°C, where 40% reduction in NO x is recorded with a TN/NO ratio of 1.6. Increasing TN/NO to 8.5 resulted in a 96% reduction. At low TN/NO ratios (<1.6), the NO x reduction potential of ARW is comparable to that of monoethanolamine, but lower than that of NH3. Nevertheless, the fact that ARW is a waste product, together with its demonstrated NO x reduction capability and its calorific value contribution, makes it attractive as an additive to combustion processes, including cement industry kilns. [Copyright &y& Elsevier]

Abstract: Utilization of biomass in combustion processes is a promising way to reduce net emission of greenhouse gas, e.g. CO2, to atmosphere. However, biomass is not likely to be successfully employed as a single feedstock due to its low energy density compared to coal. The co-combustion of coal and biomass in a circulating fluidized bed combustor (CFBC) can be employed to address this issue by improving the overall calorific value. This work investigated the influences of different biomass types on CFBC emissions. Sub-bituminous coal along with four biomass types such as palm shell, coconut shell, sawdust and rice husk were employed in study. The results indicated that the temperature profile in the riser was matter relevant to the heating value of fuel mixtures. The co-combustion of coal and palm shell gave the highest average combustion temperature, due to comparable heating value of both fuels. On the other hand, the co-combustion of coal and rice husk, which has relatively lower heating value, gave the lowest temperature. The presence of biomass in combustion was found to lead to a reduction of NO x and N2O in flue gas. The fuel-nitrogen content was observed to be a major factor for determining both NO x and N2O emission. Moreover, this work exhibited that the injection of secondary air with different position into the riser influenced the NO x and N2O concentration in the flue gas. [Copyright &y& Elsevier]

Abstract: The Alaska-adapted WRF/Chem was used to examine the benefits of the proposed North American Emission Control Area (ECA) for air quality along the Alaska coasts. Simulations were performed alternatively assuming the emissions of 2000, and the emissions of 2000 reduced by the proposed ECA-reductions. In response to the emission reductions, reductions in sulfur (nitrogen) compounds reached up to 9 km (2 km) height. Reductions of sulfate- and nitrate-in-clouds were highest at the top of the atmospheric boundary layer. The strongest reductions occurred over the ECA and the international sea-lanes for sulfur- and nitrogen-compounds, respectively. Along the Gulf of Alaska, sulfur- and nitrogen-compound concentrations decreased significantly in response to the reduced ship-emissions. They decreased over Alaska despite of unchanged emissions in Alaska. PM2.5-speciation only marginally changed in response to the reduced ship-emissions. [Copyright &y& Elsevier]

The contamination of fresh water with nitrogen compounds produced by human activities is a worldwide concern because they compromise suitable water supplies for human and animal consumption; mainly due to high toxicity of contaminating molecules and the implications in human health they have. Nitrifying bacteria do not quickly or efficiently grow because its conventional axenic autotrophic character determine their nutritional requirements. This research describes the influence of 3 sets of enriched media incubated for a period of 24 days for the development of nitrifying bacteria, numbered I, II and III. The system III was supplemented with ammonium salts to facilitate availability of the nutrient molecules. Each one of the enrichments was inoculated with a commercial bacterial set made up of the nitrifying bacteria Nitrobacter species, Nitrosomonas and Nitrospira. To evaluate the behavior of this bacterial set we assayed nitrate concentrations as a physicolchemical parameter and also measured the determined cell mass over time. The system I was not inoculated. We obtained nitrite concentration increase in systems II and III, coupled with cell mass increase up to day 24, when these values started to decrease. The cell mass was unchanged over time in system I. It is necessary to extend this protocol in order to confirm significant changes over time. [ABSTRACT FROM AUTHOR]

Several studies have assessed the effects of nitrogenous compounds on amphibian behavior. However, few have focused on the effects of their combination with other stressors or on the variation of the response to pollutants among populations. We analyzed the effect of nitrogenous compounds (NH; NO; NO, both alone and in combination) on larval behavior (activity level and location in the water column) in four populations of Pelophylax perezi naturally exposed to different levels of eutrophication. Larval activity was highest and use of the bottom of the experimental beaker was lowest at lower concentrations of nitrogenous compounds acting singly, these responses being minimal and maximal, respectively, at both control and higher concentrations. This pattern appears to fit to an hormetic reponse. Additionally, the combination of nitrogenous compounds affected more severely the response variables than when ammonium or nitrite acted singly according to an additive model. Populations inhabiting highly polluted aquatic habitats marginally showed higher activity level than the populations from less polluted environments, especially when larvae were exposed to ammonium or when nitrite appeared in combination with other nitrogen forms. Levels of activity correlated positively with larval final mass. Moreover, for similar levels of activity, larvae from polluted populations had higher growth rates than those coming from reference populations which suggests interdemic differences in behavioral sensitivity to nitrogenous pollutants. [ABSTRACT FROM AUTHOR]

Wide natural gradients of soil nitrogen (N) can be used to examine fundamental relationships between plant-soil-microbial N cycling and hydrologic N loss, and to test N-saturation theory as a general framework for understanding ecosystem N dynamics. We characterized plant production, N uptake and return in litterfall, soil gross and net N mineralization rates, and hydrologic N losses of nine Douglas-fir (Pseudotsuga menziesii) forests across a wide soil N gradient in the Oregon Coast Range (USA). Surface mineral soil N (0-10 cm) ranged nearly three-fold from 0.29% to 0.78% N, and in contrast to predictions of N-saturation theory, was linearly related to 10-fold variation in net N mineralization, from 8 to 82 kg N·ha-1·yr-1. Net N mineralization was unrelated to soil C:N, soil texture, precipitation, and temperature differences among sites. Net nitrification was negatively related to soil pH, and accounted for <20% of net N mineralization at low-N sites, increasing to 85-100% of net N mineralization at intermediate- and high-N sites. The ratio of net: gross N mineralization and nitrification increased along the gradient, indicating progressive saturation of microbial N demands at high soil N. Aboveground N uptake by plants increased asymptotically with net N mineralization to a peak of ∼35 kg N·ha-1·yr-1. Aboveground net primary production per unit net N mineralization varied inversely with soil N, suggesting progressive saturation of plant N demands at high soil N. Hydrologic N losses were dominated by dissolved organic N at low-N sites, with increased nitrate loss causing a shift to dominance by nitrate at high-N sites, particularly where net nitrification exceeded plant N demands. With the exception of N mineralization patterns, our results broadly support the application of the N-saturation model developed from studies of anthropogenic N deposition to understand N cycling and saturation of plant and microbial sinks along natural soil N gradients. This convergence of behavior in unpolluted and polluted forest N cycles suggests that where future reductions in deposition to polluted sites do occur, symptoms of N saturation are most likely to persist where soil N content remains elevated. [ABSTRACT FROM AUTHOR]

A solid oxide fuel cell (SOFC) unit is constructed with Ni-YSZ as the anode, YSZ as the electrolyte, and La0.6Sr0.4CoO3-Ce0.9Gd0.1O1.95 as the cathode. The SOFC operation is performed at 600 °C with a cathode gas simulating the lean-burn engine exhaust and at various fixed voltage, at open-circuit voltage, and with an inert gas flowing over the anode side, respectively. Electrochemical enhancement of NO decomposition occurs when an operating voltage is generated; higher O2 concentration leads to higher enhancement. Smaller NO concentration results in larger NO conversion. Higher operating voltage and higher O2 concentration can lead to both higher NO conversion and lower fuel consumption. The molar rate of the consumption of the anode fuel can be very much smaller than that of NO to N2 conversion. This makes the anode fuel consumed in the SOFC-DeNOx process to be much less than the equivalent amount of ammonia consumed in the urea-based selective catalytic reduction process. Additionally, the NO conversion increases with the addition of propylene and SO2 into the cathode gas. These are beneficial for the application of the SOFC-DeNOx technology on treating diesel and other lean-burn engine exhausts. [ABSTRACT FROM AUTHOR]

Abstract: Training on US military bases involves nonroad diesel vehicles with emissions that can affect base personnel, nearby communities, and attainment of air quality standards. Nonroad diesel engines contribute 44% of diesel PM and 12% of total NOx emissions from mobile sources nationwide. Although military sector fuel use accounts for only ≈0.4% of distillate fuel use in US, emissions factors measured for these engines improve the representation of the relatively small (as compared to onroad sources) database of nonroad emission factors. Heavy-duty multi-axle, all-wheel drive military trucks are not compatible with regular single-axle dynamometers and their emissions cannot be measured under standard laboratory conditions. We have developed a novel in-plume technique to measure in-use emissions from vehicles with elevated stack. Real-world gaseous and particulate matter (PM) emission factors (EFs) from ten 7-ton 6-wheel drive trucks and two 8-wheel drive heavy tactical Logistics Vehicle System (LVS) vehicles were measured using in-plume sampling. The EFs of these trucks are comparable to those of onroad trucks while the PM EFs of 2-stroke LVS are ≈10 times higher than those of onroad vehicles. Lower EC/PM ratio was observed for LVS compared with MTVR. PM number emission factors were 5.9 × 1014 particles km−1 for the trucks and 2.5 × 1016 particles km−1 for the LVSs, three orders of magnitude higher than the proposed European Union standard of 6 × 1011 particles km−1. The EFs sampled can be extended to engines used in the broader nonroad sector including agriculture and mining and used as inputs to the NONROAD model. [Copyright &y& Elsevier]

Increased reactive nitrogen (Nr) deposition due to expansion of agro-industry was investigated considering emission sources, atmospheric transport and chemical reactions. Measurements of the main inorganic nitrogen species (NO2, NH3, HNO3, and aerosol nitrate and ammonium) were made over a period of one year at six sites distributed across an area of ∼130,000km2 in southeast Brazil. Oxidized species were estimated to account for ∼90% of dry deposited Nr, due to the region’s large emissions of nitrogen oxides from biomass burning and road transport. NO2-N was important closer to urban areas, however overall HNO3-N represented the largest component of dry deposited Nr. A simple mathematical modeling procedure was developed to enable estimates of total Nr dry deposition to be made from knowledge of NO2 concentrations. The technique, whose accuracy here ranged from <1% to 29%, provides a useful new tool for the mapping of reactive nitrogen deposition. [Copyright &y& Elsevier]

The formation of hydroxynitropyrene (OHNP) via a photochemical reaction of 1-nitropyrene (l-NP) was demonstrated using a UV irradiation system. The photoreaction of 1-NP in methanol gave products that were hydroxy-substituted at position 1 and mono-nitro-substituted at positions 2,3, 5,6, and 8 [1-hydroxy-x-nitropyrenes (1-OH-x-NPs); x = 2, 3, 5,6, and 8]. 1-OH-2-NP and l-OH-5-NP have been identified in ambient airborne particles for the first time. On the contrary, these two OHNP isomers were not found in standard reference materials (SRM) 1650b and SRM 1975, which are typical samples of diesel exhaust particles (DEPs). The concentrations of the other OHNP isomers in the DEP samples were much lower than the concentration of l-NP, which is a representative nitro-derivative polycyclic aromatic hydrocarbon that is emitted directly from combustion sources. On the other hand, significantly higher concentration ratios of ΣOHNP (=l-OH-3-NP + 1-OH-6-NP + 1-OH-8-NP) to 1-NP were observed in ambient airborne particles than in the DEP samples. In ambient airborne particles, the mean ΣOHNP/1-NP concentration ratio of 1.4 was 35 times higher than that in SRM 1650b and 470 times higher than that in SRM 1975. The diurnal concentration of l-NP, which was observed at a typical residential area in Osaka, Japan, increased early in the morning and late in the evening, suggesting that automotive emissions contributed to the occurrence of 1-NP: The OHNP concentrations also rose in the morning, and variations of OHNP concentrations similar to those of 1-NP were observed during the daytime. However, the concentrations of OHNPs did not increase in the evening rush hour, and were low at night, i.e., in the absence of sunlight. These results support the idea that atmospheric OHNPs are predominantly formed via secondary formation processes; i.e., photochemical reactions of 1-NP are expected to have a significant effect on the occurrence of OHNPs in the atmosphere. [ABSTRACT FROM AUTHOR]

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Research on the ecosystem impacts of acidifying pollutants, and measures to control them, has focused almost exclusively on sulfur (S) and nitrogen (N) compounds. Hydrochloric acid (HCl), although emitted by coal burning, has been overlooked as a driver of ecosystem change because most of it was considered to redeposit close to emission sources rather than in remote natural ecosystems. Despite receiving little regulatory attention, measures to reduce S emissions, and changes in energy supply, have led to a 95% reduction in United Kingdom HCl emissions within 20 years. Long-term precipitation, surface water, and soil solution data suggest that the near-disappearance of HCl from deposition could account for 30-40% of chemical recovery from acidification during this time, affecting both near-source and remote areas. Because HCl is highly mobile in reducing environments, it is a more potent acidifier of wetlands than S or N, and HCl may have been the major driver of past peatland acidification. Reduced HCl loadings could therefore have affected the peatland carbon cycle, contributing to increases in dissolved organic carbon leaching to surface waters. With many regions increasingly reliant on coal for power generation, HCl should be recognized as a potentially significant constituent of resulting emissions, with distinctive ecosystem impacts. [ABSTRACT FROM AUTHOR]

To investigate the possible contamination of groundwater by wastewater leaked from the underground sewage network, water samples from 29 monitoring wells, drilled at strategic locations across Kuwait City and the adjacent residential areas, were analyzed for their inorganic and organic constituents including isotopic composition (oxygen-18 and deuterium) that can be used as tracers for source identification. As a non-conventional method, statistical processing in the form of hierarchical cluster and discriminant function analyses of the inorganic and organic data was used to group the wells according to the degree of possible contamination of groundwater. It was concluded from this analysis that more than half of the wells (17) showed little evidence of such contamination. Sample from only one of the wells suggested high degree of contamination (concentrations of total coliform bacteria (TCB) and fecal coliform bacteria (FCB) >2,000 MPN/100 ml and boron (B) concentration >11 mg/l) whereas another well appeared significantly contaminated (TCB > 2,000 MPN/100 ml; FCB > 900 MPN/100 ml; B > 4 mg/l). Three of the wells were possibly contaminated (1,000 < TCB < 2,000 MPN/100 ml; 15 < FCB < 500 MPN/100 ml; 3 < B < 11.5 mg/l), and the rest of the seven wells were classified as possibly not contaminated (TCB > 2,400 MPN/100 ml; FCB < 40 MPN/100 ml; B < 5 mg/l). The overall conclusion was that the leakage from sewage network was affecting groundwater in localized areas only. Isotope data, available for water samples from eight of the monitoring wells, tended to support the aforesaid conclusions. However, because of the use of bailing as the sampling method and lack of actual leakage surveillance, further studies need to be carried out to strengthen the reliability of these findings. [ABSTRACT FROM AUTHOR]

Abstract: The regional characteristics of estimated dry deposition and total atmospheric deposition, including dry and wet deposition, at 10 EANET sites in Japan from April 2003 to March 2008 are discussed. The components examined for dry deposition were sulfur compounds (SO2 and particulate SO4 2−) and nitrogen compounds (HNO3, NH3, particulate NO3 −, and NH4 +). Dry deposition was calculated by the product of the deposition velocity estimated by the inferential method for forest and grass surfaces and the air concentration of each compound. The 5-year mean annual dry deposition amounts for sulfur and nitrogen compounds were in the range of 5–37 and 7–50 mmol m−2 year−1, respectively. The regional characteristics of dry deposition amounts were similar between sulfur and nitrogen compounds, which showed higher deposition in the Sea of Japan side and in the Western Japan. The 5-year mean annual total deposition amounts for sulfur and nitrogen compounds were in the range of 28–77 and 22–130 mmol m−2 year−1, respectively. The contribution of dry deposition to the total deposition amounts was 10–55% and 13–56% for sulfur and nitrogen compounds, respectively. The regional characteristic of total deposition was different between sulfur and nitrogen compounds. Total deposition amounts in Japan were larger than those in CASTNET and EMEP because of high wet deposition, which implied that the increasing emissions of air pollutants in East Asia caused high atmospheric depositions. [Copyright &y& Elsevier]

Abstract: The amount of odorants effused from Lake Sihwa during the low tide period was estimated using sediment samples collected from various sites. A wide variety of odorants released from lake sediment were measured such as reduced sulfur compounds (RSCs), aldehydes, nitrogenous compounds, volatile organic compounds (VOCs), and volatile fatty acids (VFAs). A comparison of emission rates (μg m−2 min−1) showed large mean values from such species as NH3 (14,550), toluene (370), and DMS (106), while the lowest values were seen from VFAs and some VOCs. If their emission concentrations are converted into odor intensity (OI), the OI values were dominated by such odorants as NH3 (2.07), H2S (1.65), DMS (1.80), acetaldehyde (1.52), butyric acid (1.59), butyraldehyde (1.28), isovaleric acid (1.15), and valeric acid (0.78). The dilution to threshold (D/T) ratio derived on the basis of the air dilution sensory (ADS) test yielded a mean of 62 (range: 10–173); 19 out of 21 samples were seen to exceed the guideline D/T value of 15. The sum of odor intensities derived from individual odorants exhibited strong compatibilities with the D/T ratio (r 2 = 0.87; α = 0.003). The overall results of this study confirm that the sediment can play an important role in the malodor phenomenon in the area surrounding the Lake Sihwa. [Copyright &y& Elsevier]

The purpose of this investigation was to remove the organic nitrogen compounds from petroleum-derived diesel fuels. These nitrogen compounds can cause environmental problems, as well as fuel instability problems that can degrade fuels and affect engine performance. Fuels were treated with two different filtering media, activated clay and silica tel. The methylene chloride extracts from both the activated clay and silica gel were subjected to GC/MS analysis. Close to 99% of the total organic nitrogen compounds were removed. About 60% of the nitrogen compounds identified consisted of pyridines, quinolines and tetra-hydroquinolines made up 26%, while indoles and carbazoles about 10% of the total nitrogen compounds. Of the nitrogen heterocyclics identified, indoles and carbazoles were linked to fuel instability reactions. The proposed method was tested on diesels fuels from a variety of countries and found to remove between 97.8 and 99.9% of the N-compounds. The results of this study showed that both of these filtering materials were effective in removing the organic nitrogen compounds and resulted in fuels that exhibited excellent storage stability. These simple filtering methods can be independent of the refining process and do result in an environmentally cleaner burning fuel. [ABSTRACT FROM AUTHOR]

Experiments were conducted to elucidate the mechanism of the reaction between free chlorine and urea. In combination with findings of previous investigations, the results of these experiments indicate a process by which urea undergoes multiple N-chlorination steps. The first of these steps results in the formation of N-chlorourea; this step appears to require Cl2 to proceed and is the overall rate-limiting step in the reaction for conditions that correspond to most swimming pools. N-Chlorourea then appears to undergo further chlorine substitution; the fully N-chlorinated urea molecule is hypothesized to undergo hydrolysis and additional chlorination to yield NCl3 as an intermediate. NCl3 is hydrolyzed to yield NH2Cl and NHCl2, with subsequent decay to stable end products, including N2 and NO3-. Conversion of urea-N to nitrate is pH-dependent. The pattern of nitrate yield is believed to be attributable to the fact that when urea serves as the source of reduced-N, entry into the reactions that describe chlorination of ammoniacal nitrogen is through NCl3, whereas when NH3 is the source of reduced-N, entry to these reactions is through NH2Cl. [ABSTRACT FROM AUTHOR]

Nanoscale zero-valent iron (Fe was synthesized for nitrate denitrification. The reduction efficiency of nitrate decreased quickly with increasing initial pH value, increased considerably with the increasing dosage of nanoscale Fe0 and did not vary much with initial nitrate concentrations changing from 20 to 50mg1-1 when the excessive amount of nanoscale Fe0was utilized. With reductive denitrification of nitrate by nanoscale Fe0 the removal rate of nitrate reached 96.4% in 30 min with nanoscale Fe0 dosage of 1.0 gI-1 and pHin 6.7, and more than 85% of the nitrate was transformed into ammonia. Kinetics analysis in batch studies demonstrates that the denitrification of nitrate by nanoscale Fe involves reaction on the metal surface, which fits well the pseudo-first order reaction with respect to nitrate concentration. The observed reaction rate constant of reductive denitrification of nitrate was determined to be 0.086min-1 with a nanoscale Fe dosage of 1.0gl-1 and pHin 6.7. Fast and highly effective denitrification can be achieved by nanoscale Fe0 compared with commercial Fe powder, this is due to the extremely high surface area and high reactivity for nanoscale Fe0 which can enhance the denitrification efficiencies remarkably. [ABSTRACT FROM AUTHOR]

Nonpoint source pollution is the leading cause of the U.S.’s water quality problems. One important component of nonpoint source pollution control is an understanding of what and how watershed-scale conditions influence ambient water quality. This paper investigated the use of spatial regression to evaluate the impacts of watershed characteristics on stream NO3NO2-N concentration in the Cedar River Watershed, Iowa. An Arc Hydro geodatabase was constructed to organize various datasets on the watershed. Spatial regression models were developed to evaluate the impacts of watershed characteristics on stream NO3NO2-N concentration and predict NO3NO2-N concentration at unmonitored locations. Unlike the traditional ordinary least square (OLS) method, the spatial regression method incorporates the potential spatial correlation among the observations in its coefficient estimation. Study results show that NO3NO2-N observations in the Cedar River Watershed are spatially correlated, and by ignoring the spatial correlation, the OLS method tends to over-estimate the impacts of watershed characteristics on stream NO3NO2-N concentration. In conjunction with kriging, the spatial regression method not only makes better stream NO3NO2-N concentration predictions than the OLS method, but also gives estimates of the uncertainty of the predictions, which provides useful information for optimizing the design of stream monitoring network. It is a promising tool for better managing and controlling nonpoint source pollution. [Copyright &y& Elsevier]

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Abstract: The environmental burden associated with some functionalization reactions of nitrogen-heteroaromatics via TiO2 (solar) photocatalysis is compared with the same reactions under thermal conditions. Two methods, LCA (Life Cycle Assessment) and EATOS (Environmental Assessment Tool for Organic Synthesis), both based on a detailed analysis of the experiments, are used for the assessment. The thermal processes are consistently evaluated to give a better environmental performance. Photocatalysis is disfavored by the required management of a large amount of excess reagent and solvent involved. Still the good yield and simplicity of the photocatalytic method are promising (and are positively evaluated by a third assessment, EcoScale). The precautions for making photocatalytic syntheses environmentally viable are discussed. [Copyright &y& Elsevier]