Increase In Ammonia Concentration Research Articles

Effects of ammonia stress on liver microstructure, antioxidant capability and inflammation‐related genes and post‐exposure recovery in the hybrid sturgeon ( Acipenser baerii ♀ × Acipenser schrencki ♂)

Ammonia is an important water quality factor, which causes several adverse effects in fish. In this study, the 5-month-old hybrid sturgeon (Acipenser baerii ♀ × Acipenser schrencki ♂) with a mean body weight of 50 ± 0.5 g was subjected to ammonia stress (0 mg/L, control group; 10 mg/L, low-concentration group; 50 mg/L, high-concentration group) for 48 h and followed by recovery for 48 h, changes of liver tissue, antioxidant enzyme activity and relative expressions of inflammation-related genes were observed. The results showed that, with an increasing ammonia concentration and exposure duration, hepatocytes showed swelling, congestion and indistinguishable cellular outline. After 48 h of recovery, the degree of swelling decreased, nuclear shifted, and vacuolation reduced; however, the normal levels before stress application were not reached again. Additionally, compared with the control group, the activities of superoxide dismutase, catalase and glutathione peroxidase were significantly upregulated 6 h after stress. Malondialdehyde reached the maximum at 24 h in the low-concentration group and at 12 h in the high-concentration group, indicating the activity of the antioxidant system trying to protect cells from oxidative stress. Furthermore, the relative expression levels of interleukin 1 beta, tumour necrosis factor α genes and heat shock proteins (both HSP70 and HSP90β) in the liver were induced by ammonia stress. These results provide direct evidence for the damage caused by ammonia stress and the self-recovery ability of the hybrid sturgeon.

Dynamic changes in anaerobic digester metabolic pathways and microbial populations during acclimatisation to increasing ammonium concentrations

Transitions in microbial community structure in response to increasing ammonia concentrations were determined by monitoring mesophilic anaerobic digesters seeded with a predominantly acetoclastic methanogenic community from a sewage sludge digester. Ammonia concentration was raised by switching the feed to source segregated domestic food waste and applying two organic loading rates (OLR) and hydraulic retention times (HRT) in paired digesters. One of each pair was dosed with trace elements (TE) known to be essential to the transition, with the other unsupplemented digester acting as a control. Samples taken during the trial were used to determine the metabolic pathway to methanogenesis using 14C labelled acetate. Partitioning of 14C between the product gases was interpreted via an equation to indicate the proportion produced by acetoclastic and hydrogenotrophic routes. Archaeal and selected bacterial groups were identified by 16S rRNA sequencing, to determine relative abundance and diversity. Acclimatisation for digesters with TE was relatively smooth, but OLR and HRT influenced both metabolic route and community structure. The 14C ratio could be used quantitatively and, when interpreted alongside archaeal community structure, showed that at longer HRT and lower loading Methanobacteriaceae were dominant and hydrogenotrophic activity accounted for 77% of methane production. At the higher OLR and shorter HRT, Methanosarcinaceae were dominant with the 14C ratio indicating simultaneous production of methane by acetoclastic and hydrogenotrophic pathways: the first reported observation of this in digestion under mesophilic conditions. Digesters without TE supplementation showed similar initial changes but, as expected failed to complete the transition to stable operation.

Comparative studies on the response of Zostera marina leaves and roots to ammonium stress and effects on nitrogen metabolism.

Coastal eutrophication has resulted in the rapid loss and deterioration of seagrass beds worldwide. The high concentration of ammonium in eutrophic aquatic environments has been invoked as the main cause. In this study, leaves and roots of the seagrass Zostera marina were treated with simulated eutrophic seawater with elevated ammonium concentrations. The tolerance to ammonium stress and mechanism of nitrogen metabolism detoxification in different tissues were investigated. The results showed that high ammonium stress significantly affected the growth of leaves and had a negative effect on photosynthesis. The root activity of Z. marina was not inhibited at ammonium concentrations of ≤100mg/L, indicating that the roots exhibited tolerance to ammonium stress. Increasing ammonium concentrations led to a higher increase of ammonium and free amino acid (FAA) contents in leaves than in roots. However, nitrogen storage decreased in Z. marina leaves after high ammonium treatments. The enzyme activity and gene expression of glutamine synthetase (GS) in roots were significantly higher than in the leaves even under ammonium stress. Meanwhile, ammonium stress increased the enzyme activities and gene expression of glutamate synthase (GOGAT) and glutamate dehydrogenase (GDH) in roots, which suggested that the roots had a strong ability to assimilate ammonium under ammonium stress. In contrast, although the GOGAT and GDH activity and gene expression in the leaves were initially increased, they significantly decreased when the ammonium concentration exceeded 100mg/L. These results indicated that the concentration of 100mg/L might be a threshold marking a transition from tolerance to toxicity for the leaves. Our study demonstrates that Z. marina leaves could be prone to higher damage than roots because the mechanism of ammonium assimilation in leaves is more susceptible to ammonium toxicity.

Evaluation of catalysts for decomposition of ammonia in hydrogen isotope purification systems

Four catalyst materials were evaluated for suitability for use as ammonia decomposition catalysts in hydrogen isotope impurity removal systems for tritium processing in fusion systems. Suitability was tested both in terms of a comparison of the selected catalysts in ≥80% hydrogen environments, and in terms of compatibility in tritium service. Four different catalysts were characterized and tested, including ruthenium on alumina (Ru/Al), ruthenium on carbon (Ru/C), nickel on alumina (Ni/Al), and iron (Fe). Nickel on alumina may be the most compatible for use in tritiated environments, while still showing comparable performance to the ruthenium on alumina. In higher concentrations of hydrogen, the Ru/C catalyst was unstable and degraded its carbon support by catalytic hydrogenation of the carbon. The catalytic performance of the iron catalyst was shown to be less than the Ni/Al and Ru/Al, and other considerations on the nitridation of iron in the studied conditions are discussed. The catalytic performance of the nickel on alumina was shown to increase with increasing temperature, decreasing flow rate, decreasing pressure, and increasing ammonia concentration.

Assessing temporal dynamics on pelagic Sargassum influx and its relationship with water quality parameters in the Mexican Caribbean

Since 2011, massive inflows of pelagic Sargassum have been recorded in the Caribbean region, which has affected coastal ecosystems, mainly water quality and the flora and fauna that inhabit these areas. The aim of this study is to evaluate the temporal dynamics of Sargassum arrival and its relationship on water quality in three sites of the Mexican Caribbean (Mahahual, Xahuayxol and Xcalak). We used remote sensing tools to estimate Sargassum coverage and turbidity to know if these parameters vary throughout the year and are related. We measured in situ water quality parameters to identify variations, depending on the Sargassum quantity and leachate concentration. Our results of 26 Landsat 8-OLI images show higher Sargassum coverage and turbidity during the winter months and a high relationship between Sargassum coverage and turbidity in areas near the coast. Additionally, turbidity calculated from multispectral bands complemented satellite detection of Sargassum, as high turbidity values were identified in near-shore areas where satellite images could not detect the alga. Finally, water quality parameters showed an increase in ammonium concentration and decreased pH and oxygen levels in the areas with higher Sargassum accumulation and leachate concentration. This study provides a better understanding about temporal dynamics of Sargassum influx in the southern Mexican Caribbean and its relationship with water turbidity in order to develop strategies, management plans and harvesting policies that could prevent huge masses of Sargassum reaching the coast.

Effect of selected wastewater characteristics on estimation of SARS-CoV-2 viral load in wastewater

Wastewater-based epidemiology has been used as a tool for surveillance of COVID-19 infections. This approach is dependent on the detection and quantification of SARS-CoV-2 RNA in untreated/raw wastewater. However, the quantification of the viral RNA could be influenced by the physico-chemical properties of the wastewater. This study presents the first use of Adaptive Neuro-Fuzzy Inference System (ANFIS) to determine the potential impact of physico-chemical characteristics of wastewater on the detection and concentration of SARS-CoV-2 RNA in wastewater. Raw wastewater samples from four wastewater treatment plants were investigated over four months. The physico-chemical characteristics of the raw wastewater was recorded, and the SARS-CoV-2 RNA concentration determined via amplification with droplet digital polymerase chain reaction. The wastewater characteristics considered were chemical oxygen demand, flow rate, ammonia, pH, permanganate value, and total solids. The mean SARS-CoV-2 RNA concentrations ranged from 648.1(±514.6) copies/mL to 1441.0(±1977.8) copies/mL. Among the parameters assessed using the ANFIS model, ammonia and pH showed significant association with the concentration of SARS-CoV-2 RNA measured. Increasing ammonia concentration was associated with increasing viral RNA concentration and pH between 7.1 and 7.4 were associated with the highest SARS-CoV-2 concentration. Other parameters, such as total solids, were also observed to influence the viral RNA concentration, however, this observation was not consistent across all the wastewater treatment plants. The results from this study indicate the importance of incorporating wastewater characteristic assessment into wastewater-based epidemiology for a robust and accurate COVID-19 surveillance.

Increased ammonium levels occurring during benthic algal blooms are potentially toxic to fucalean algae

Abstract During the spring of 2016, benthic blooms of Acinetospora crinita (Ectocarpales, Phaeophyceae) producing voluminous mucilaginous aggregates frequently occurred at surveyed locations of the west Istrian Coast (northern Adriatic Sea, Croatia). In mucilage-affected macroalgal assemblages, the concentration of ammonium ranged from 50 to 300 μM. To investigate whether ammonium has the potential to harm fucalean species, a selected taxon, Cystoseira compressa was exposed to increased ammonium concentrations in laboratory conditions. Experiments revealed that exposure to 50 μM ammonium severely damaged the thalli while exposure to 300 μM caused complete necrosis of thalli in 2 days. These findings suggest that benthic algal blooms, enhanced by climate change and eutrophication, can negatively affect the populations of fucalean species due to production of ammonium during the decay of mucilaginous aggregates, causing thallus necrosis.

Performance of a dual-chamber microbial fuel cell as biosensor for on-line measuring ammonium nitrogen in synthetic municipal wastewater

This study investigates the performance of microbial fuel cells (MFC) for on-line monitoring ammonium (NH4+-N) in municipal wastewater. A double chamber microbial fuel cell (MFC) was established in a continuous mode under different influent ammonium concentrations ranging from 5 to 40 mg L−1. Results indicated that excess ammonium would inhibit the activity of electrogenic bacteria in the anode chamber and consequently affect electricity production. An inversely linear relationship between concentration and voltage generation was obtained with coefficient R2 0.99 and the MFC could detect up to 40 mg L−1 of NH4+-N. Notably, no further decline was observed in voltage output and there was in fact a further increase in ammonia concentration (>40 mg L−1). The stability and high accuracy of ammonium-based MFC biosensors exposed competitive results compared to traditional analytical tools, confirming the biosensor's reliability. Furthermore, pH 7.0; R 1000 Ω and HRT of 24 h are the best possible conditions for the MFC biosensor for monitoring ammonium. The simplicity in design and operation makes the biosensor more realistic for practical application.

Responses of energy homeostasis and lipid metabolism in Penaeus vannamei exposed to ammonia stress

Ammonia accumulates in the process of shrimp culture and has a strong toxic effect on shrimp survival, physiological metabolism and immune function. Shrimp can adapt to ammonia stress by regulating lipid metabolism. In the present study, to explore the regulatory mechanism of lipid metabolism in ammonia tolerance of Penaeus vannamei (3.08 ± 0.40 g) based on the energy supply, a 96-h ammonia stress experiment was conducted, and energy homeostasis and lipid metabolism responses in the hepatopancreas, muscle and gills of shrimp were observed at total ammonia concentrations of 0 (control group), 6.42, 32.11, and 64.22 mg/L. The cumulative mortality of shrimp increased significantly with increasing ammonia stress concentration. Exposure to ammonia stress significantly decreased the content of adenosine triphosphate (ATP) and the adenylate energy charge (AEC) in the hepatopancreas, muscle and gills, whereas the relative expression of the AMPK, TOR, and SREBP genes was significantly upregulated. The activities of fatty acid synthase (FAS), acetyl-coenzyme A carboxylase (ACC), and carnitine palmitoyltransferase I (CPT-1) and the peroxisome proliferator-activated receptor-α (PPAR-α) level in the hepatopancreas were significantly increased, whereas the opposite was observed in the muscle and gills. In general, the triglyceride (TG) content of the hepatopancreas increased significantly with increasing ammonia concentration. The results indicated that ammonia stress reduced cellular energy levels in the hepatopancreas, muscle and gills of P. vannamei, thereby inducing the activation of the AMPK signaling pathway in these tissues and resulting in increased levels of lipid decomposition and energy supply in the hepatopancreas. However, the activation of the AMPK pathway did not improve the levels of lipid decomposition or energy supply in the shrimp muscle and gills.

СТРУКТУРА И ДИНАМИКА ФИТОПЛАНКТОНА БОЛЬШИХ МЕЛКОВОДНЫХ ЗАРАСТАЮЩИХ ОЗЕР (ВОЖЕ И ЛАЧА, ВОЛОГОДСКАЯ И АРХАНГЕЛЬСКАЯ ОБЛАСТИ, РОССИЯ)

A comparative analysis of the diversity, abundance, biomass, composition of dominant species, size characteristics of phytoplankton and saprobity of the waters of shallow large overgrown lakes Vozhe, Lacha, as well as the rivers Svid and Onega in June 2015 is presented. The data obtained are compared with the results of previous studies in the 1970s years. It was found that in the 2000s, there was a significant increase in the number of phytoplankton in lakes and a change in the composition of dominant species. Non-heterocyst cyanoprokaryotes (Aphanocapsa holsatica, Planktolyngbya limnetica) began to dominate in phytoplankton, which is associated with increase of ammonium concentration. The average biomass of phytoplankton in lakes (2.6 g/m3) has remained practically unchanged since the 1970s and was typical for mesotrophic type waters. In the Lacha Lake characterized by lower transparency, high degree of overgrowth, salinity and saprobity of waters, phytoplankton was distinguished by lower floristic diversity, higher abundance, dominance level, and the smallest cell sizes.

Synergistic ammonia and fatty acids inhibition of microbial communities during slaughterhouse waste digestion for biogas production

The slaughterhouse waste (SHW) contains high organics which makes SHW a feasible feedstock for anaerobic digestion (AD). The present study systematically assessed the microbiome response and biomethanation along with the production of volatile fatty acids (VFAs) and ammonia under 2%, 4%, 6%, and 8% (w v−1) loadings of SHW in AD. The optimum loading was 2% SHW which resulted in maximum biomethane production and VFAs consumption. A higher SHW concentration (4% and 6%) resulted in a prolonged lag-phase and decreased biomethane production. High VFAs (28.88 g L−1) and ammonia nitrogen (>4 g L−1) accumulation were observed at 8% SHW leading to permanent inhibition of biomethane and methanogenic archaea. An increase in ammonia and VFAs concentration, at 4% and 6% SHW loadings, shifted the methanogenic pathway from acetoclastic to hydrogenotrophic lead by Methanoculleus. Acetoclastic Methanosaeta (77.15%) dominated the reactors loaded with 2% SHW resulting in the highest biomethane production.

Electrochemical ZnO-Based Impedimetric Sensor for Aqueous Ammonia Detection for Precision Animal Agriculture

Electrochemical ZnO-Based Impedimetric Sensor for Aqueous Ammonia Detection for Precision Animal Agriculture

Assessment of Hazard Due to Release of Gaseous Ammonia from the Fly Ash-Water Mixture Applied in Longwall Mine Gobs

Purpose The introduction of flue gas denitrification technologies by selective catalytic reduction (SCR) or selective non-catalytic reduction (SNCR) in coal fired plants resulted in an increase of ammonia content in fly ash. The utilization of fly ash in fire and ventilation prevention of hard coal mines causes the release of ammonia from a fly ash-water mixture. In the applied technology of the ash and water mixture, ammonia in gaseous form is discharged and mixes with the air flowing through the mine airways. In this article, reference is made to the risk assessment of gaseous ammonia in the longwall area during the application of the fly ash-water mixture to the gobs in the U-tube ventilation system. Methods The test methods include: ammonia release from ash and water mixtures at various temperatures and in respect to different proportions of water to ash with use of a multigas analyzer with an FTIR detector. Results The results of the laboratory tests helped to determine the size of the ammonia stream released from the fly ash-water mixture in respect to different ratios of water to ash. Practical implications Laboratory studies allow for ventilation and gaseous analysis to assess the level of ammonia risk, in the mine airways, from exhaust air discharged from the longwall area. Originality/value Based on the literature review, this type of research has not been carried out so far.

Integration of a porous wood-based triboelectric nanogenerator and gas sensor for real-time wireless food-quality assessment

Monitoring the quality of perishable food in real time is critical for reducing the societal costs and foodborne diseases. A self-powered triboelectric nanogenerator (TENG)-based wireless gas sensor system (TWGSS) is presented to realize selective, sensitive, and real-time wireless food-quality assessment in a cold-supply chain. TWGSS can real-time monitor the key food spoilage markers gas (e.g., ammonia) and maintain excellent stability under high humidity (75%) and low temperature (−18 °C). Benefiting from the three-dimensional porous structure of wood and ammonia sensitive properties of the carbon nanotubes materials, output voltage of the TENG selectively decreases with the increase of ammonia concentrations from 50 to 500 ppm. Moreover, the TENG exhibits an ammonia-sensing response of 0.85 at 500 ppm ammonia, which is much higher than the other common gases released from perishable foods under the same gas concentrations. Through system integration and power management, a self-powered triboelectrically driven system that can also be used as a gas sensor and wirelessly transmit data to the user interfaces. This work provides a design concept for the application area of the TENGs to the assessment of food quality, and also promotes the development of self-powered systems in food industry. ● A wood-based triboelectric nanogenerator (TENG) was developed and used as NH 3 sensor. ● The self-powered TWGSS was proposed by integrating the TENG with the wireless circuitry. ● The TWGSS realized real-time wireless food-quality assessment in a cold-supply chain.

EFFECTS OF UREA - AMMONIATION AND COTTON SEED CAKE SUPPLEMENTATION ON THE UTILIZATION OF SORGHUM STOVER BY SHEEP

The effects cotton seed cake (CSC) supplementation and urea-ammoniation on utilization of sorghum stover by Yankasa sheep was studied. Chopped sorghum stover was ensiled with fertilizer grade urea at 4% urea (w/w), the urea being dissolved in water to reconstitute the silage to 50% DM. The experiment was a 2x3 factorial design of unammoniated and ammoniated sorghum stover and three levels of CSC supplementation (0.5, 1.0 and 1.5% of the sheep body weight). The growth trial was conducted with 24 yearling sheep, averaging 18.2 kg liveweight and lasted for 60 days. Intake of sorghum stover by sheep was Improved (P<0.05) by urea-ammoniation, not significant (P>0.05). Increasing the level of supplementation with CSC improved (P>0.05) stover intake by sheep fed the ammoniation of unammonlated stover, but resulted in decreased (P>0.05) intake of ammonlated by sheep. Sheep liveweight gains were improved by ammoniation and supplementation (P<0.01). The interaction between urea-ammoniation of stover and supplementation resulted in better (P<0.05) live weight going in sheep. Twelve Yankasa ruang averaging 16.9 kg liveweight were Ammoniation and supplementation did not affect DM, NDF and ADF digestibilities (P>.05), but resulted in increase (P<0.05) in cellulose and hemicellulose digestion. Ammoniation and supplementation resulted in N-balance of the sheep. Ammoniation resulted in marked Increases (P <0.01) in rumen ammonia concentrations, but increasing 50% DM. The material was epsiled above the level of supplementation did not appreciably(P<0.05) silled rumen ammonia concentrate

An Investigation of the Ammonia-Sensing Mechanism of α-MoO3-Based Chemi-Resistive Sensors

Chemi-resistive ammonia sensors based on alpha-phase molybdenum trioxide (α-MoO3) are a simple and selective technology for measuring the concentration of gaseous ammonia for applications such as human breath sensing and monitoring selective catalytic reduction (SCR) systems [1-7]. The basic operating principle of these sensors is the correlation between the electrical resistance of the sensor and the concentration of ammonia to which the sensor is exposed. Typically, the sensor consists of an interdigitated electrode substrate covered with the α-MoO3 film [1-7]. The electrical resistance of the α-MoO3 film changes as a function of ammonia concentration. This change in resistance of the α-MoO3 film is commonly attributed to the alteration of the charge depletion layer (Λ) of the α-MoO3 particles through the reaction of ammonia with adsorbed oxygen species [5-9]. For α-MoO3, the charge depletion layer model predicts that the resistance of the film should decrease with increasing ammonia concentration. In addition to the charge depletion layer model, other sensing mechanisms have been suggested, such as the partial reduction by ammonia of the surface of the α-MoO3 film [1,2] and the formation of oxygen vacancies in the α-MoO3 lattice [3].The α-MoO3 film can be fabricated by a variety of methods, including sol-gel synthesis, ion beam deposition, hydrothermal synthesis, and flame spray pyrolysis [1-6]. In this work, the α-MoO3 film is fabricated using Reactive Spray Deposition Technology (RSDT) followed by annealing to develop crystallinity. The RSDT is a flame-based process that can be used for the fabrication of α-MoO3 films at a commercial scale. The initial development of ammonia sensors with RSDT-fabricated α-MoO3 films of varying morphology was presented at the 236th ECS Meeting as an oral presentation, “Ammonia-Sensing Properties of α-MoO3 Fabricated by Reactive Spray Deposition Technology (RSDT).” From these initial sensors, the sensor with the strongest response to ammonia was selected for further testing at concentrations between 0.1 ppm and 5 ppm ammonia in dry air at 400°C. These sensing results and the materials characterization of the sensor by SEM and XRD before and after 80 hours of continuous testing are reported in Ebaugh et al. [7] and are shown in Figures 1-3. In Figure 1, the sensing results among the three test cycles comprising the 80 hours of testing are quite repeatable; however, the results consistently depart from the prediction of the charge depletion layer model between 3 ppm and 5 ppm.To better explain this unexpected sensing behavior, additional electrochemical testing and materials characterization is needed. Specifically, normal pulse voltammetry (NPV) can be used to provide data pertaining to the electronic path through the α-MoO3 film and the reaction and transport of chemical species adsorbed on the α-MoO3 film. TEM analysis of the α-MoO3 can show the nanoscale morphology of the sensing material. It is well established that the nanoscale morphology of the metal-oxide film impacts its sensing behavior [8-10]. XPS can also be used to investigate the possible reduction of the surface of the α-MoO3 particles and the formation of oxygen vacancies in the α-MoO3 lattice. Data from the materials characterization of the sensing film (XRD, SEM, TEM, and XPS) will be used in conjunction with sensing results and NPV data to develop an explanation for the sensor behavior observed in [7]. An understanding of the ammonia-sensing mechanism will help to guide the optimization of the RSDT-fabricated α-MoO3 film to improve the performance of the sensor for a wide range of applications.References A. K. Prasad, et al. Thin Solid Films. 436 2003 pp. 46-51.P. Gouma, et al. IEEE Sensors Journal. 10 (1) 2010 pp. 49-53.A. K. Prasad, et al. Sensors and Actuators B: Chemical. 93 2003 pp. 25-30.P Gouma, et al. Journal of Breath Research. 5 2011 p. 037110.A. T. Güntner, et al. Sensors and Actuators B: Chemical. 223 2016 pp. 266-273.D. Kwak, et al. ACS Applied Materials & Interfaces. 11 2019 pp. 10697-10706.T. A. Ebaugh, et al. ACS Applied Materials & Interfaces. Under review.C. S. Rout, et al. Nanotechnology. 18 2007 p. 205504.M. E. Franke, et al. Small. 2 (1) 2006 pp. 36-50.N. Barsan, et al. Fresenius Journal of Analytical Chemistry. 365 1999 pp. 287-304. Figure 1

Electrical Impedance of V2O5/POMA Hybrid Film Deposited by Casting for Application in Ammonia Gas Sensor

The sensitivity evaluation of a vanadium pentoxide/poly-o-methoxyaniline hybrid material (V2O5/POMA) using casting deposition for the preparation of an ammonia gas sensor was investigated herein. V2O5/POMA was produced by the intercalation of V2O5 via sol–gel and o-methoxyaniline monomers. V2O5/POMA thin film deposition onto electrodes was performed by casting. The electrical studies confirmed that V2O5/POMA exhibited increased complex impedance as a function of increasing ammonia concentration. The conductivity of the film decreased with increasing ammonia concentration due to the de-doping process. According to theoretical adjustment, a significant increase in the bulk and interfacial electrical resistance in the presence of ammonia was observed. The combination of these effects contributed to the high sensitivity of the prepared film in both the real and imaginary components of the complex impedance for ammonia gas in a range of 0 to 100 ppm, which indicated that the film is a good candidate for use as an ammonia sensing material.

Snowmelt periods as hot moments for soil N dynamics: a case study in Maine, USA.

The vernal transition represents the seasonal transition to spring, occurring as temperatures rise at the end of winter. With rapid snowmelt, microbial community turnover, and accelerated nutrient cycling, this is a critical but relatively under-studied period of ecosystem function. We conducted a study over two consecutive winters (2015-2016) at the Bear Brook Watershed in Maine to examine how changing winter conditions (warming winters, reduced snow accumulation) altered soil nitrogen availability and stream N export during winter and the vernal transition, and how these patterns were influenced by ecosystem N status (N-enriched vs. N-limited). Of the two study years, 2016 had a warmer winter with substantially less snow accumulation and a discontinuous snowpack-and as a result, had a longer vernal transition and a snowpack that thawed before the vernal transition began. Across both years, snowmelt triggered a transition, signaled by increased ammonium concentrations in soil, decreased soil nitrate concentrations due to flushing by meltwater, and increased stream nitrate exports. Despite the contrasting winter conditions, both years showed similar patterns in N availability and export, differing only in the timing of these transitions. The vernal transition has conventionally been considered a critical period for biogeochemical cycling, because the associated snowmelt event triggers physicochemical and biochemical changes in soil systems. This was consistent with our results in 2015, but our data for 2016 show that this may not always hold true, and instead, that warmer, low-snow winters may demonstrate a temporal asynchrony between snowmelt and the vernal transition. We also show that ecosystem N status is a strong driver of the seasonal N pattern, and the interaction of N status and changing climate must be further investigated to understand ecosystem function under our current predicted trajectory of warming winters, declining snowfall, and winter thaw events.

Ammonium Cycling and Nitrification Stimulation during Oil Sludge Remediation by Gram-Positive Bacteria Lysinibacillus sphaericus Using Red Wiggler Earthworm Eisenia fetida

The performance of a mixture between L. sphaericus and E. fetida was evaluated for ammonium cycling and nitrifying bacteria stimulation during oil sludge remediation. The addition of E. fetida significantly increased ammonium concentration (p = 0.0218) and total Colony-forming units (CFU) count p = 0.02848). However, oil sludge with worms and L. sphaericus reached lower ammonium concentrations and CFU counts than sludge with worms alone. Sludge inoculated only with L. sphaericus presented higher ammonium concentration than sludge without inoculum, but the bacterial population reached a lower density during the final days. Final DNA and RNA extractions from all treatments amplified for L. sphaericus putative amoA and Gram-negative nitrifying bacteria amoA genes correlated with diminished ammonium concentrations during the final days of the experiment. Final RNA extractions for L. sphaericus amplified for Molybdenum transporter gene suggesting possible nitrogen fixation by L. sphaericus. The addition of Red Wiggler Earthworm to oil sludge remediation systems may provide better conditions for bacterial populations to carry out hydrocarbon degradation. The addition of E. fetida to a L. sphaericus crude oil biodegradation system may improve soil ammonium concentrations and nitrifying activity, and this could be crucial in oil sludge remediation because of bacterial inhibition due to high C:N ratios. The final product of this process may be used for soil enhancement due to its richness in nutrients and beneficial bacterial populations.

Performance of thin film composite membranes for ammonium removal and reuse of ammonium-enriched solution for plant growth

Abstract Ammonium is known to be one of the most significant pollutants in water bodies. The presence of ammonium in water is mainly originated from agricultural activities, domestic sewage and industrial effluent. This study evaluates the performance of two commercial thin film composite (TFC) membranes, i.e., NF270 and XLE from FilmTec™ for ammonium removal using synthetic wastewater and domestic sewage. The filtration experiment was conducted at different feed ammonium concentrations, humic acid concentrations, pHs and pressure. Results showed that the membrane rejection against ammonium increased dramatically with increasing ammonium concentration. However, the membrane flux was slightly compromised at higher ammonium concentration. With respect to pH, highest ammonium removal rate was able to be achieved at an optimum pH of 10. Besides, the permeation flux increased gradually with increasing feed pressure. From the results, the XLE membrane outperformed the NF270 membrane in terms of ammonium rejection. The retentate of XLE membrane filtration process was found to be useful as liquid fertiliser for plant growth. The results indicated that the TFC membrane process is not only able to produce permeate with an ammonium concentration below the acceptable limit of 10 mg/L but also able to produce retentate with enriched ammonium for plant growth.