Concentrations Of NO3 Research Articles

Investigating the Concentration of NO3- and Heavy Metals in Some Leafy Vegetables in the Greenhouses of Kermanshah County

Investigating the Concentration of NO3- and Heavy Metals in Some Leafy Vegetables in the Greenhouses of Kermanshah County

Riparian vegetation influences aquatic greenhouse gas production in an agricultural landscape

Although riparian vegetation is widely acknowledged for its positive impact on soil and water quality and its role in regulating terrestrial greenhouse gas emissions in agricultural landscapes, there remains a gap in understanding how different types of riparian vegetation affect aquatic greenhouse gas production. Thus, the objective of this study was to investigate whether the type of vegetation within riparian zones influenced aquatic environmental factors, subsequently impacting aquatic greenhouse gas emissions. To address this, we measured greenhouse gases in the aquatic environment bordered by riparian zones with herbaceous vegetation (GRS) compared to undisturbed natural riparian forests dominated by deciduous (UNF-D) or coniferous (UNF-C) vegetation or a rehabilitated riparian forest (RH). Our findings indicate that aquatic CO2 concentrations were not influenced (p < 0.05) by vegetation type ranging from 9 g L−1 to 11 g L−1. In contrast, aquatic CH4 concentrations were significantly lower (p < 0.05) in treed riparian zones, ranging from 14 μg L−1 to 24 μg L−1, compared to a riparian zone with herbaceous vegetation (34 μg L−1). However, we observed significantly higher (p < 0.05) aquatic N2O concentrations in treed riparian zones (9.5 μg L−1 to 10.3 μg L−1), particularly those dominated by coniferous vegetation (23.0 μg L−1), compared to the riparian zone with herbaceous vegetation (7.7 μg L−1). The total CO2-C equivalent (i.e., CO2 + CH4 + N2O) was highest in the riparian zone with coniferous trees (UNF-C: 10,717 mg CO2-Ceq L−1), followed by the GRS (9494 mg CO2-Ceq L−1), RH (9423 mg CO2-Ceq L−1) and UNF-D (9,183 mg CO2-Ceq L−1) riparian zone. Moreover, riparian vegetation was influenced by various environmental factors that likely controlled physicochemical and biological processes related to the production of greenhouse gases within the aquatic environment.

Application of Cu@Cu foam and RuO2@Ti for removal of nitrogen compounds and organic matters from non-standard treated municipal wastewater by continuous electrochemical process: Optimization and mechanism

Public health, potable water supplies, and ecosystems are endangered by the disposal or reuse of non-standard effluents of wastewater treatment plants. To achieve the Sustainable Development Goals (SDG 6) and USEPA quality standards, this work utilized an innovative electrochemical technique with continuous flow. Cu@Cu foam and RuO2@Ti were prepared for NO3 reduction and NH4 and COD oxidation, respectively. The characterization of electrodes was performed by XRD, EDS, FTIR, FE-SEM, and CV analysis. The effects of parameters including NH4 concentration (10–30 mg N/L), NO3 concentration (4–12 mg N/L), current (0.5–1.5 A), and Cl- concentration (100–400 mg/L) were examined for the removal of NH4, NO3, and COD. Characterization results confirmed that Cu and RuO2 were successfully coated on the surface of electrodes. Operating parameters were optimized using response surface methodology. The ideal conditions for current, Cl- concentration, and HRT were 1.5 A, 347.7 mg/L, and 120 min, respectively for concentrations of 9 mg /L NO3-N, 30 mg/L NH4-N, and 30 mg/L COD. Under these conditions, NO3-N, NH4-N, and COD removal efficiencies were 78 %, 97.8 %, and 61.2 %, respectively. The proposed electrochemical process was a sustainable technology for the concurrently removal nitrogen and carbon with advantages including environmental compatibility, versatility merits, and simplicity.

Gas production characteristics of oats and tritical silages and techniques for reducing gas emissions1

Greenhouse gas (GHG) production during ensiling not only causes the nutrient losses of silage but also promotes climate warming. However, there is little information on the production of GHG and strategies for mitigating GHG emissions during ensiling. This work aimed to study the gas production characteristics and techniques for reducing gas emissions during ensiling. Oats and triticale, with Lactiplantibacillus plantarum (LP) or corn meal (CM) addition, were ensiled. The cumulative gas volume rapidly increased and reached to the peak within the first 9 days of ensiling for both forage crops. The highest cumulative gas volume of triticale silage was twice as much as that of oats silage. Triticale silage produced lower carbon dioxide (CO2) concentration, higher methane (CH4) and nitrous oxide (N2O) concentrations than oats silage within the 28 days of ensiling. Adding LP or CM significantly improved the fermentation quality and decreased the gas volume and GHG concentrations of two silages on d56 (except CH4 of triticale). At the early stage of ensiling, more Enterobacter, Lactococcus and Leuconostoc related to gas production were observed, and adding LP increased the abundance of Lactobacillus and decreased the abundance of bacteria like Kosakonia, Pantoea, Enterobacter and Lactococcus positively correlated with gas volume, CO2 and N2O concentrations. These results suggest that gas formation during ensiling mainly occurs in the first 9 days. Adding LP or CM can significantly improve the fermentation quality and decrease the gas volume. This would benefit to reducing GHG emissions in silage production.

Exploring the Spatiotemporal Heterogeneity of Stream Nitrogen Concentrations in a Typical Human‐Activity‐Influenced Headwater Watershed in South China

AbstractStream nitrogen concentrations significantly impact nitrogen loads and greenhouse gas emissions, but their spatiotemporal heterogeneity and human influences remain highly uncertain. This study thoroughly explored the spatiotemporal variations in stream nitrogen concentrations in a typical headwater watershed in South China. Spatially distributed measurements were conducted during 2020–2022, and mathematical modeling was implemented based on incorporating these data. More than 4,400 data points were collected for water temperature and concentrations of ammonium nitrogen (NH4‐N), nitrate nitrogen (NOx‐N), dissolved total nitrogen (DTN), total nitrogen (TN), and dissolved oxygen. Results showed that NOx‐N was the largest component of TN, with average concentrations of 1.20 and 1.66 mg L−1, respectively. The stream N2O concentration could be predicted using NH4‐N and NOx‐N concentrations via the Michaelis‐Menten equation. Significant downstream decreases in NH4‐N, NOx‐N, DTN, and TN concentrations were identified in the largest river in the watershed, and clear spatial differences in these nitrogen concentrations existed among the three main rivers. Clear seasonal and annual variations in stream nitrogen concentrations were observed. NH4‐N, NOx‐N, DTN, and TN concentrations correlated with cumulative precipitation from the preceding 8–12 days, while stream N2O concentrations correlated over 13–20 days. Stream N2O concentrations and emissions averaged 12.77 nmol L−1 and 1.12 nmol m−2 s−1, respectively, and were lower in summer than in other seasons. Upstream tea plantations, villages, and adjacent agricultural lands significantly affected nitrogen concentrations, while overflow dams did not. These findings highlight nitrogen cycle's complexity and the need for high‐resolution data to guide effective watershed management.

Dual isotope analysis reveals the COVID-19 lockdown impact on nitrate aerosol sources and formation pathways in Shanghai

Nitrate (NO3−) is an important contributor to PM2.5 which can adversely affect the environment and human health. A noticeable decrease in NOx concentrations has been reported due to the lockdown measures implemented to curb the spread of Corona Virus Disease 2019 (COVID-19). However, questions remain, regarding the nonlinear relationship between NOx and NO3−. Here, we collected PM2.5 samples in two periods, before and during the lockdown of COVID-19 in Shanghai. Dual isotopes (δ18O-NO3− and δ15N-NO3−) of NO3− were measured to investigate the formation pathways and potential sources of NO3−. The results showed that the concentration of NO3− decreased significantly during the lockdown period compared to the period before the lockdown. Additionally, the hydroxyl pathway was the dominant contributor to NO3− production during the lockdown period, while N2O5 hydrolyses dominated the formation of NO3− before the lockdown. This change is largely attributable to alterations in the oxidative potential of the environment. In comparison to the period preceding the lockdown, the relative contributions of each NOx source remained largely unchanged throughout the lockdown periods. Nevertheless, the concentration of NO3− contributed by each NOx source exhibited a notable decline, particularly the mobile sources and coal combustion. Furthermore, the reduction extent of NO3− due to the lockdown period was also greater than the reduction during the Clean Air Actions (2013–2017). Our findings provide evidence that the COVID-19 lockdown led to a decrease in NO3− concentration due to changes in the formation pathway and reductions in NOx emissions from various sources.

Wastewater treatment plant effluents increase the global warming potential in a subtropical urbanized river

Rivers play a pivotal role in global carbon (C) and nitrogen (N) biogeochemical cycles. Urbanized rivers are significant hotspots of greenhouse gases (GHGs, N2O, CO2 and CH4) emissions. This study examined the GHGs distributions in the Guanxun River, an effluents-receiving subtropical urbanized river, as well as the key environmental factors and processes affecting the pattern and emission characteristics of GHGs. Dissolved N2O, CO2, and CH4 concentrations reached 228.0 nmol L–1, 0.44 mmol L–1, and 5.2 μmol L–1 during the wet period, and 929.8 nmol L–1, 0.7 mmol L–1, and 4.6 μmol L–1 during the dry period, respectively. Effluents inputs increased C and N loadings, reduced C/N ratios, and promoted further methanogenesis and N2O production dominated by incomplete denitrification after the outfall. Increased urbanization in the far downstream, high hydraulic residence time, low DO and high organic C environment promoted methanogenesis. The strong CH4 oxidation and methanogenic reactions inhibited by the effluents combined to suppress CH4 emissions in downstream near the outfall, and the process also contributed to CO2 production. The carbon fixation downstream from the outfall were inhibited by effluents. Ultimately, it promoted CO2 emissions downstream from the outfall. The continuous C, N, and chlorine inputs maintained the high saturation and production potential of GHGs, and altered microbial community structure and functional genes abundance. Ultimately, the global warming potential downstream increased by 186 % and 84 % during wet and dry periods on the 20-year scale, and increased by 91 % and 49 % during wet and dry periods on the 100-year scale, respectively, compared with upstream from the outfall. In urbanized rivers with sufficient C and N source supply from WWTP effluents, the large effluent equivalently transformed the natural water within the channel into a subsequent "reactor". Furthermore, the IPCC recommended EF5r values appear to underestimate the N2O emission potential of urbanized rivers with high pollution loading that receiving WWTP effluents. The findings of this study might aid the development of effective strategies for mitigating global climate change.

Impact of Heatwaves and Declining NOx on Nocturnal Monoterpene Oxidation in the Urban Southeastern United States.

Nighttime oxidation of monoterpenes (MT) via the nitrate radical (NO3) and ozone (O3) contributes to the formation of secondary organic aerosol (SOA). This study uses observations in Atlanta, Georgia from 2011-2022 to quantify trends in nighttime production of NO3 (PNO3) and O3 concentrations and compare to model outputs from the EPA's Air QUAlity TimE Series Project (EQUATES). We present urban-suburban gradients in nighttime NO3 and O3 concentrations and quantify their fractional importance (F) for MT oxidation. Both observations and EQUATES show a decline in PNO3, with modeled PNO3 declining faster than observations. Despite decreasing PNO3, we find that NO3 continues to dominate nocturnal boundary layer (NBL) MT oxidation (FNO3 = 60%) in 2017, 2021, and 2022, which is consistent with EQUATES (FNO3 = 80%) from 2013-2019. This contrasts an anticipated decline in FNO3 based on prior observations in the nighttime residual layer, where O3 is the dominant oxidant. Using two case studies of heatwaves in summer 2022, we show that extreme heat events can increase NO3 concentrations and FNO3, leading to short MT lifetimes (<1 h) and high gas-phase organic nitrate production. Regardless of the presence of heatwaves, our findings suggest sustained organic nitrate aerosol formation in the urban SE US under declining NOx emissions, and highlight the need for improved representation of extreme heat events in chemistry-transport models and additional observations along urban to rural gradients.

Nitrous oxide emissions and soil profile responses to manure substitution in the North China Plain drylands

Substituting synthetic fertilizers with manures in agriculture enhances soil properties and crop yield. However, the impact on nitrous oxide (N2O) emissions, especially from the soil profile, remains poorly understood. This study examined emissions from 2017 to 2019 on a well-established (>10-year) maize field site in the North China Plain. Three treatments were compared: 100 % synthetic nitrogen (NPK), 50 % synthetic fertilizer N + 50 % manure N substitution (50%MNS), and 100 % manure N substitution (100%MNS). N2O emissions were monitored for three years, and in 2019, N2O concentrations at 20 cm and 40 cm soil depths were analyzed in relation to surface N2O fluxes and environmental factors. The results showed manure substitution resulted in about 13.8 %–25.2 % (50%MNS) and 40.3 %–72.2 % (100%MNS) reduction in N2O emissions over the 3-year period compared with the NPK treatment. Throughout the maize growing season, the top-dressing accompanied by rainfall was responsible for the N2O emissions. The difference in N2O concentrations between all the treatments at 20 cm depth was insignificant, but at 40 cm depth the N2O concentrations were significantly higher for the 50%MNS treatment than the other treatments. The N2O fluxes and N2O concentration were not synchronized especially in NPK. The decoupled relationship between the N2O fluxes and the N2O concentration in the soil profile depth suggested the contribution of N2O produced in the soil profile to the surface N2O fluxes is limited. This study highlights that manure substitution is an efficient measure to reduce N2O emissions.

Wastewater-effluent discharge and incomplete denitrification drive riverine CO2, CH4 and N2O emissions

Rivers are well-known sources of the greenhouse gasses (GHG) carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). These emissions from rivers can increase because of anthropogenic activities, such as agricultural fertilizer input or the discharge of treated wastewater, as these often contain elevated nutrient concentrations. Yet, the specific effects of wastewater effluent discharge on river GHG emissions remain poorly understood. Here, we studied two lowland rivers which both receive municipal wastewater effluent: river Linge and river Kromme Rijn. Dissolved concentrations and fluxes of CH4, N2O and CO2 were measured upstream, downstream and at discharge locations, alongside water column properties and sediment composition. Microbial communities in the sediment and water column were analysed using 16S rRNA gene sequencing. In general, observed GHG emissions from Linge and Kromme Rijn were comparable to eutrophic rivers in urban and agricultural environments. CO2 emissions peaked at most discharge locations, likely resulting from dissolved CO2 present in the effluent. CH4 emission was highest 2 km downstream, suggesting biological production by methanogenic activity stimulated by the effluents' carbon and nutrient supply. Dissolved N2O concentrations were strongly related to NO3− content of the water column which points towards incomplete riverine denitrification. Notably, methanogenic archaea were more abundant downstream of effluent discharge locations. However, overall microbial community composition remained relatively unaffected in both rivers. In conclusion, we demonstrate a clear link between wastewater effluent discharge and enhanced downstream GHG emission of two rivers. Mitigating the impact of wastewater effluent on receiving rivers will be crucial to reduce riverine GHG contributions.

Evaluating seasonal variation in macronutrient levels and their impact on water quality in urban coastal waters: A case study in nutrient management along the North Colombo coast of Sri Lanka

Macronutrients are vital for sustaining marine food webs and primary production. However, their overabundance through riverine inflows and untreated wastewater discharges causes adverse ecological changes, especially in developing countries, necessitating effective nutrient management for ecosystem preservation. We assessed macronutrient enrichment and dispersion patterns in the north Colombo coast of Sri Lanka, an urban estuary stressed by untreated wastewater discharge from sewer channels and macronutrients from the Kelani River. Maximum concentrations of NO3−−N, total dissolved nitrogen, PO43−−P and total dissolved phosphorus were 0.085, 0.74, 0.70, and 0.79 mg/L, respectively, while the dissolved oxygen levels and temperature ranged from 6.42 to 8.62 mg/L and from 28.1 to 30.8 0C during January 2023. The estuary was a nitrogen-limited ecosystem, with the Kelani River being the primary source of NO3−−N. Although nutrient levels were within water quality guidelines, understanding how pollutants disperse during a catastrophic discharge is crucial for risk management. Simulated dispersion patterns using Delft3D revealed that NO3−−N and other solutes introduced through the Kelani River accumulate near the breakwaters of the Colombo harbor complex during the Northeast monsoon, primarily due to seasonal wave and wind conditions. The accumulation of the limiting nutrient increased the risk of eutrophication and harmful algal blooms by non-indigenous toxic algae species introduced by untreated ballast water disposal. The findings elucidate the critical role of breakwaters in retaining solutes and emphasize the influence of morphological, climatic, and topographical factors on dispersion patterns in coastal ecosystems. The study provides an example for developing countries to integrate cost-effective monitoring technologies and numerical modelling into coastal management, facilitating data-driven decision making for effective environmental management.

Homogeneously Mixed Cu-Co Bimetallic Catalyst Derived from Hydroxy Double Salt for Industrial-Level High-Rate Nitrate-to-Ammonia Electrosynthesis.

Electrocatalytic nitrate reduction reaction (NO3RR) presents an innovative approach for sustainable NH3 production. However, selective NH3 production is hindered by the multiple intermediates involved in the NO3RR process and the competitive hydrogen evolution reaction. Hence, the development of highly efficient NO3RR catalysts is paramount. Herein, we report highly efficient bimetallic catalysts derived from hydroxy double salt (HDS). Under NO3RR conditions, Cu1Co1-HDS undergoes in situ reconstruction, forming nanocomposites of homogeneously distributed metallic Cu0 and Co(OH)2. Reconstruction-induced Cu0 rapidly converts NO3- to NO2-, which is further hydrogenated to NH3 by Co(OH)2. Homogeneously mixed Cu and Co species maximize this synergistic effect, achieving outstanding NO3RR performance including the highest NH3 yield rate (4.625 mmol h-1 cm-2) reported for powder-type NO3RR catalysts. Integration of Cu1Co1-HDS with a commercial Si solar cell attained 4.53% solar-to-ammonia efficiency from industrial wastewater-level concentrations of NO3- (2000 ppm), demonstrating practical application potential for solar-driven NH3 production. This study provides a strategy for enhancing the NH3 yield rate by optimizing the compositions and distributions of Cu and Co.

Toxicity of antimony to plants: Effects on metabolism of N and S in a rice plant

Excess antimony (Sb) has been shown to damage plant growth. Rice plants readily absorb a large amount of Sb after a long period of flooding, yet the mechanisms underlying Sb toxicity in plants have not been solved. This study was conducted to explore the effects of Sb on the uptake of N and S, and monitor the concentrations of reduced glutathione (GSH) and enzymes associated with these processes. In addition, we analyzed differentially expressed metabolites (DEMs) correlated with amino acids (AAs) and oligopeptides, specifically DEMs containing sulfur (S), GSH and indole–3–acetic acid (IAA). The results showed that antimonite [Sb(III)] inhibited shoot growth whereas antimonate [Sb(V)] stimulated shoot growth. Interestingly, Sb(III)5/10 enhanced shoot concentrations of total nitrogen (N), NH4+–N [only at Sb(III)10] and S; but reduced the shoot concentrations of NO3–N and soluble protein. Sb(III)5/10 addition significantly increased oxidized glutathione (GSSG) concentration and activities of glutathione peroxidase (GSH–Px) and glutathione S-transferase (GST) but non–significantly affected concentration of reduced glutathione (GSH) and activities of γ-glutamylcysteine synthetase (GCL) and glutathione reductase (GR), suggesting Sb(III) restricted GSH recycling. Addition of Sb (1) increased the abundance of DEMs associated with lignins, Ca uptake, toxicity/detoxification, and branched chain AAs; (2) decreased the abundance of AAs inclcuding isoleucine (Ile), leucine (Leu), tryptophan (Trp), tyrosine (Tyr) and histidine (His); (3) increased the abundance of arginine (Arg), putrescine (Put) and spermidine (Spd); and (4) affected methylation and acetylation of many AAs, especially acetylation.

Nitrate, Nitrite, and Iodine Concentrations in Commercial Edible Algae: An Observational Study.

Edible algae are a natural source of nutrients, including iodine, and can also contain nitrogen in the form of nitrate (NO3-) and nitrite (NO2-) as they can fix nitrogen from seawater. This study aimed to analyse the NO3-, NO2-, and iodine concentrations in eighteen macroalgae and five microalgae species commercially available in the United Kingdom. NO3- and NO2- concentrations were measured using high-performance liquid chromatography (HPLC), and iodine was determined using inductively coupled plasma mass spectrometry (ICP-MS). NO3- and iodine concentrations in macroalgae (NO3-: 4050.13 ± 1925.01 mg/kg; iodine: 1925.01 ± 1455.80 mg/kg) were significantly higher than in microalgae species (NO3-: 55.73 ± 93.69 mg/kg; iodine: 17.61 ± 34.87 mg/kg; p < 0.001 for both). In the macroalgae group, nori had the highest NO3- (17,191.33 ± 980.89 mg/kg) and NO2- (3.64 ± 2.38 mg/kg) content, as well as the highest iodine content. Among microalgae, Dunaliella salina had the highest concentration of NO3- (223.00 ± 21.93 mg/kg) and iodine (79.97 ± 0.76 mg/kg), while Spirulina had the highest concentration of NO2- (7.02 ± 0.13 mg/kg). These results indicate that commercially available edible algae, particularly macroalgae species, could be a relevant dietary source of NO3- and iodine.

The electrochemical mechanism of biochar for mediating the product ratio of N2O/(N2O + N2) in the denitrification process

The biochar electrochemical properties and surface functional groups significantly impact N2O production and reduction during denitrification process. However, its effects on N2O emissions during the denitrification process and its electrochemical mechanisms remain unclear. The study examined the impact of pristine and oxidized biochar combined with two types of nitrogen fertilizers on the N2O/(N2O + N2) ratio and N2O emissions in an incubation experiment with seven treatments: (1) CK (no application of chemical fertilizer); (2) N1 (applying (NH4)2SO4); (3) N1B ((NH4)2SO4 + pristine biochar); (4) N1BO ((NH4)2SO4 + oxidized biochar); (5) N2 (applying KNO3); (6) N2B (KNO3 + pristine biochar); (7) N2BO (KNO3 + oxidized biochar). The study found that in comparison with applying nitrogen fertilizer alone, combining pristine biochar decreased soil N2O concentration by 7.1 %–85.8 %, while combining oxidized biochar increased it by 15.7 %–125.6 %. Applying pristine biochar reduced N2O/(N2O + N2) ratio by 10.4 %–86.2 %, whereas applying oxidized biochar increased it by 12.9 %–121.6 %. The application of pristine biochar increased the nosZ gene abundance and decreased the (nirS + nirK)/nosZ ratio, which contributed to reducing N2O to N2. Compared with oxidized biochar, the oxygen-containing functional groups of pristine biochar decreased by 46.6 %, and it possessed a higher specific surface area (23.01 m2 g−1) and electrical conductivity (0.003 mS cm−1). The correlation analysis showed that DOC and inorganic nitrogen were the key environmental factors affecting N2O emissions. Additionally, the electrical conductivity, specific capacitance, and oxygen-containing functional groups of the biochar were identified as the main factors driving N2O emissions. The SEM analysis suggested that the indirect influence of biochar electrochemical properties on N2O emissions was greater than its direct influence. Our work provides fresh perspectives on reducing soil N2O emissions and establishes a theoretical foundation for the subsequent preparation of biochar materials with enhanced N2O reduction capabilities.

Inorganic Characterization of Feeds Based on Processed Animal Protein Feeds.

The potential of utilizing inorganic constituents in processed animal proteins (PAPs) for species identification in animal feeds was investigated, with the aim of using these constituents to ensure the quality and authenticity of the products. This study aimed to quantify the inorganic content across various PAP species and assess whether inorganic analysis could effectively differentiate between PAP species, ultimately aiding in the identification of PAP fractions in animal feeds. Four types of PAPs, namely bovine, swine, poultry, and fish-based, were analyzed and compared to others made up of feathers of vegetal-based feed. Also, three insect-based PAPs (Cricket, Silkworm, Flour Moth) were considered in this study to evaluate the differences in terms of the nutrients present in this type of feed. Ionic chromatography (IC) was used to reveal the concentrations of NO3-, NO2, Cl-, and SO42-, and inductively coupled plasma optical emission spectroscopy (ICP-OES) to detect Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, Si, Sr, Ti, and Zn. The application of multivariate chemometric techniques to the experimental results allowed us to determine the identification capability of the inorganic composition to identify correlations among the variables and to reveal similarities and differences among the different species. The results show the possibility of using this component for discriminating between different PAPS; in particular, fish PAPs are high in Cd, Sr, Na, and Mg content; swine PAPs have lower metal content due to high fat; feathers and vegetal feed have similar Al, Si, and Ni, but feathers are higher in Fe and Zn; and insect PATs have nutrient levels comparable to PAPs of other origins but are very high in Zn, Cu, and K.

Applying paleoclimatic reconstruction of greenhouse gases and correlation analysis of global and Yangtze Estuary SST changes with industrial revolution

This study explores the differences of different proxies in paleoclimatological reconstruction. It was found that N2O content increased first and then decreased after the first industrial revolution, while CO2 and CH4 content increased. After the Second Industrial Revolution, the three kinds of greenhouse gases all increased sharply, and the amplitude was relatively consistent. The analysis shows that the annual variation of the Changjiang Estuary is larger than that of the whole world, showing a canine shape. Compared with other historical thermal events, it is found that global change is directly related to the Industrial Revolution.

Numerical modeling of a coal/ammonia Co-fired fluidized bed: Control and kinetics analysis of nitrogen oxides emissions

The potential increase in nitrogen oxide emissions in the coal/ammonia co-firing can hinder the large-scale utilization of ammonia to reduce carbon emissions. In this work, a fluidized bed simulation model was established to investigate the NOx and N2O behaviors in the process of coal/ammonia co-firing. The effects of several variables on nitrogen oxides emission characteristics were studied, including the ammonia ratio, temperature, excess air ratio, and air/ammonia distribution strategies. The findings indicate that NOx and N2O concentrations rise and then decline with the NH3 co-firing ratio (CR-NH3) increased, peaking at 10 % and 5 % CR-NH3. The formation of N2O is insensitive to the addition of ammonia, while NOx emissions vary dramatically with different ammonia ratios. Higher temperatures enhance the formation of NOx but inhibit the generation of N2O within 750 °C–950 °C. As the temperature rises, the primary decomposition path of N2O shifts from N2O→N2H2→NNH→N2 to N2O→NO2→NO→N2. The generations of NOx and N2O are both enhanced due to the weakness of the reduced atmosphere with the excess air ratio increased. When the primary air ratio is raised, N2O gradually takes over as the main source of nitrogen oxides instead of NOx. The specific primary air ratio in the fluidized bed should be considered in the priority treatment of NOx or N2O in the process of lowering nitrogen oxides emissions. Ammonia distribution strategies have opposite effects on NOx and N2O emissions. With more NH3 introduced as a secondary fuel, the dilute phase area can change from the main source of NO to the consumption area of NO. The present findings can help control the emissions of nitrogen oxides during coal/ammonia co-combustion in coal-fired circulating fluidized bed power plants.

In Situ Raman Spectroscopy of Plasma Electrochemical and Plasma Catalytic Reactors

Plasma electrochemistry (PEC) has been under investigation for an expanding number of potential applications such as agriculture, water treatment, decarbonized chemical processing, and nanomaterials synthesis [1–4]. PEC in water leads to the formation of gas-phase species that undergo a cascade of processes in the liquid to produce aqueous species such as OH, H2O2, ONOOH, NO2 -, and NO3 - that are sought after in these applications. Plasma-assisted catalysis (PAC) is another growing research field for some of the same applications and others that occur in the gas phase, such as industrial catalyst decoking, VOC abatement, gas reforming, and CO2 conversion [5]. For such problems, popular catalysts include zeolites, TiO2, and CeO2 [6]. Similar to PEC, in PAC the operating conditions for catalysis become more relaxed (e.g. lower temperature to activate the catalyst). There can be plasma-catalyst synergistic effects that improve the process yield well beyond that using plasma or catalyst alone.In both PEC and PAC, the plasma produces energetic photons, electrons, ions, and excited species, and enhances the electric field near plasma-liquid and plasma-solid interfaces. These strongly non-equilibrium conditions enable the plasma to perform the required processes for these applications in many cases in a single step and without assistance, compared to conventional methods that can require multiple steps, potentially toxic chemical agents (e.g. acids, reducing agents), and/or external heating.A major challenge facing the development of PEC- and PAC-related applications is the direct and detailed experimental investigation of the plasma-liquid and plasma-catalyst interfacial regions, respectively. The majority of existing liquid- and solid-phase diagnostics must be performed ex situ, removed from the plasma reactor and after treatment. To extend the scope of diagnostics, we employ an in situ approach using multiple diagnostic techniques to study a wide range of physical and chemical properties at the plasma-water interface. The centrepiece of this platform is in situ spontaneous Raman microspectroscopy, which is advantageous because of its non-intrusiveness, selectivity, versatility, and straightforward calibration. Shaping the laser beam into a light sheet enables probing of the interfacial region with micron-scale spatial resolution. For PEC in pure water, in situ Raman spectra showed that the concentrations of aqueous H2O2 and NO3 - both exceed those of the bulk liquid at a depth of a few tens of microns from the plasma-liquid interface [7].We will focus on transient changes to Raman spectra that appear in the presence of plasma, then disappear when the plasma is switched off. Such changes are observable in situ, not ex situ, and indicate the energy exchange from the plasma to water or the catalyst surface. The general approach will be to establish relationships between plasma properties and changes to the Raman spectra. Two primary cases will be studied. First, we will study PEC in air plasma-water systems at atmospheric pressure, using both batch reactor and electrospray configurations. We will focus on the spectral profile of the –OH stretch band of water and of probe molecules such as NO3 -. Analysis of the –OH stretch band reveals that the plasma weakens the hydrogen bonding network of water. To help pinpoint the cause, we will track the broadening of the N-O symmetric stretch mode (v 1) of NO3 - at less than 20 µm depth from the plasma-liquid interface. Second, we will investigate a PAC reactor consisting of a low- to medium-pressure CO2 plasma in contact with CeO2 as a catalyst. In this case, the catalyst temperature will be tracked using the Stokes-to-anti-Stokes ratio of the Raman intensities of the first-order optical phonon of CeO2, as well as the spectral shift of this spectral feature. Acknowledgments Financial support: Campus France Franco-Thai PhD fellowship (French Embassy in Thailand, E4C Engie sponsorship), IP Paris Energy4Climate “E4C” Interdisciplinary Center, Campus France PHC Stefanik project (49885SJ), CNRS-IEA “GRAFMET”, EUR PLASMAScience, Fédération Plas@Par, ANR grant ANR-15-CE06-0007-01 References [1] T. Orriere, D. Kurniawan, Y.-C. Chang, D. Z. Pai, and W.-H. Chiang, Nanotechnology 31, 485001 (2020).[2] J.-S. Yang, D. Z. Pai, and W.-H. Chiang, Carbon 153, 315 (2019).[3] S. Kooshki, P. Pareek, R. Mentheour, M. Janda, and Z. Machala, Environmental Technology & Innovation 32, 103287 (2023).[4] D. S. Mallapragada et al., Joule 7, 23 (2023).[5] E. Baratte, C. A. Garcia-Soto, T. Silva, V. Guerra, V. I. Parvulescu, and O. Guaitella, Plasma Chemistry and Plasma Processing s11090-023-10421-z (2023).[6] C. A. Garcia-Soto, E. Baratte, T. Silva, V. Guerra, V. I. Parvulescu, and O. Guaitella, Plasma Chemistry and Plasma Processing s11090-023-10419-7 (2023).[7] D. Z. Pai, Journal of Physics D: Applied Physics 54, 355201 (2021).

Effects of enriched CO2, temperature, and irrigation on soil properties in greenhouse apple tree cultivation

The significant contributions of anthropogenic activity to global warming are evidenced by the increasing average atmospheric temperatures and CO2 concentration. To date, data on the impact of global warming on crops, particularly field-scale fruit growth and the soil environment, remain lacking. Therefore, we conducted a 4-year monitoring experiment on semi-closed apple tree populations cultivated under the present or near-future climate to assess the effects of atmospheric temperature and CO2 concentrations on soil moisture, temperature, and inorganic ion concentration. Apple saplings were grown in three independent environment-controlled greenhouses, namely greenhouses A (GH_A; control), B (GH_B; high-temperature), and C (GH_C; high-temperature and high CO2), representing climate modification experiments. The pH increased by 0.02, 0.20, and 0.12/year for GH_A, GH_B, and GH_C, respectively. In particular, GH_B (standard irrigation plot; STD) showed a significant pH increase of 0.25/year. The EC increased by 0.014 mS/cm/year for GH_A, decreased by -0.010 mS/cm/year for GH_B, and increased by 0.006 mS/cm/year for GH_C, showing no clear overall increasing or decreasing trend. The NO3 concentration increased by 1.2 mg/L/year for GH_A, decreased by 10.2 mg/L/year for GH_B and decreased by 0.7 mg/L/year for GH_C. The apparent activation energy (Ea) ranged from 85.3 to 214.4 (kJ/mol NH4+) and, regardless of watering treatment, GH_A > GH_B > GH_C. The values in STD plots were 1.4 to 1.7 times those in abundant irrigation plots. Using GH_A (STD) as a standard, the soil temperature dependence of the nitrification rate did not change overall at high or low air temperatures with increasing watering (Ea = 150.5 kJ/mol) or heating (Ea = 154.1 kJ/mol). The soil temperature dependence of the nitrification rate did not vary under heating and increased watering (Ea = 89.5 kJ/mol) or under heating, increased watering, and increased CO2 (Ea = 85.3 kJ/mol). This study provides novel insights into determining the environmental impacts of apple tree community soils under near-future climatic conditions.