Nitrogen Source Research Articles

Methylotrophic bacteria from rice paddy soils: mineral-nitrogen-utilizing isolates richness in bulk soil and rhizosphere.

Methanol, the second most abundant volatile organic compound, primarily released from plants, is a major culprit disturbing atmospheric chemistry. Interestingly, ubiquitously found methanol-utilizing bacteria, play a vital role in mitigating atmospheric methanol effects. Despite being extensively characterized, the effect of nitrogen sources on the richness of methanol-utilizers in the bulk soil and rhizosphere is largely unknown. Therefore, the current study was planned to isolate, characterize and explore the richness of cultivable methylotrophs from the bulk soil and rhizosphere of a paddy field using media with varying nitrogen sources. Our data revealed that more genera of methylotrophs, including Methylobacterium, Ancylobacter, Achromobacter, Xanthobacter, Moraxella, and Klebsiella were enriched with the nitrate-based medium compared to only two genera, Hyphomicrobium and Methylobacterium, enriched with the ammonium-based medium. The richness of methylotrophic bacteria also differed substantially in the bulk soil as compared to the rhizosphere. Growth characterization revealed that majority of the newly isolated methanol-utilizing strains in this study exhibited better growth at 37°C instead of 30 or 45°C. Moreover, Hyphomicrobium sp. FSA2 was the only strain capable of utilizing methanol even at elevated temperature 45°C, showing its adaptability to a wide range of temperatures. Differential carbon substrate utilization profiling revealed the facultative nature of all isolated methanol-utilizer strains with Xanthobacter sp. TS3, being an important methanol-utilizer capable of degrading toxic compounds such as acetone and ethylene glycol. Overall, our study suggests the role of nutrients and plant-microbial interaction in shaping the composition of methanol-utilizers in terrestrial environment.

PSIV-21 Ileal digestibility of amino acids in feed ingredients for 22-, 56-, and 87-kilogram pigs

Abstract The objective of the present study was to test the hypothesis that the apparent ileal digestibility (AID) of amino acids (AA) in feed ingredients is not constant in pigs with 3 different body weights (BW). Eight pigs with initial BW of 22.2 ± 1.2 kg cannulated at the distal ileum were used. Two experimental diets contained corn distillers dried grains with solubles (DDGS) and soybean meal-wheat mixture (SBM-W; 70% soybean meal + 30% wheat) as the sole source of nitrogen, respectively. The diets were assigned to the animals in a 2-period cross-over design. Each period consisted of a 5-d adaptation period and a 2-d ileal digesta collection period. The animals, diets, and experimental design for 50 kg pigs (initial BW = 55.6 ± 3.3 kg) and 80 kg pigs (initial BW = 86.9 ± 5.1 kg) were identical to those used for 22 kg pigs. Orthogonal polynomial contrasts were used to determine the effect of ingredient type (corn DDGS or SBMM) and BW of pigs (from 22 to 87 kg) and the interaction between these 2 main effects. The AID of crude protein, lysine, and methionine in both corn DDGS and SBM-W linearly or quadratically increased (P < 0.05) with an increase in pig BW. An interaction between ingredient type and linear effect of BW was observed (P < 0.05) in histidine, isoleucine, leucine, phenylalanine, threonine, and valine. Specifically, a linear increase in AID of these AA with increasing BW of pigs was greater in SBM-W compared with corn DDGS. In conclusion, the AID values of most AA differed between the BW range of 22 to 87 kg, and these patterns varied among different ingredients.

Kelps may compensate for low nitrate availability by using regenerated forms of nitrogen, including urea and ammonium.

Nitrate, the form of nitrogen often associated with kelp growth, is typically low in summer during periods of high macroalgal growth. More ephemeral, regenerated forms of nitrogen, such as ammonium and urea, are much less studied as sources of nitrogen for kelps, despite the relatively high concentrations of regenerated nitrogen found in the Southern California Bight, where kelps are common. To assess how nitrogen uptake by kelps varies by species and nitrogen form in southern California, USA, we measured uptake rates of nitrate, ammonium, and urea by Macrocystis pyrifera and Eisenia arborea individuals from four regions characterized by differences in nitrogen availability-Orange County, San Pedro, eastern Santa Catalina Island, and western Santa Catalina Island-during the summers of 2021 and 2022. Seawater samples collected at each location showed that overall nitrogen availability was low, but ammonium and urea were often more abundant than nitrate. We also quantified the internal %nitrogen of each kelp blade collected, which was positively associated with ambient environmental nitrogen concentrations at the time of collection. We observed that both kelp species readily took up nitrate, ammonium, and urea, with M. pyrifera taking up nitrate and ammonium more efficiently than E. arborea. Urea uptake efficiency for both species increased as internal percent nitrogen decreased. Our results indicate that lesser-studied, more ephemeral forms of nitrogen can readily be taken up by these kelps, with possible upregulation of urea uptake as nitrogen availability declines.

160 Awardee Talk: Impact of indigestible protein on coccidiosis and meat and bone meal autoclaving time-related reduction in amino acid digestibility for broiler chickens and growing pigs

Abstract Meat and bone meal (MBM) is a byproduct of the processing of livestock in the rendering industry. Because of its highly digestible protein and balanced amino acid profile, MBM is a valuable protein source in swine and poultry diets. Rendering may reduce amino acid digestibility of MBM because of heat damage to MBM, and the effect of heat damage on amino acid digestibility in MBM may be different between broiler chickens and growing pigs. For this reason, the objective of this study was to determine the effect of autoclaving on standardized ileal digestibility (SID) of amino acid in MBM fed to broiler chickens and growing pigs. Meat and bone meal from the same batch was autoclaved at 134°C for 0, 30, 60, 90, 120, 150, or 180 min, generating 7 samples. Eight experimental diets consisted of 7 diets containing each MBM sample as a sole source of nitrogen and a nitrogen-free diet. In Exp. 1, male broiler chickens [n = 656; initial body weight (BW) = 777 ± 69 g] at d 18 post hatching were assigned to the 8 diets in a randomized complete block design with BW as a blocking factor. On d 23, birds were euthanized by CO2 asphyxiation and dissected for the collection of ileal digesta. In Exp. 2, barrows (n = 16; initial BW = 25.7 ± 1.0 kg) surgically fitted with T-cannulas at the distal ileum were allotted to duplicate 8 × 4 incomplete Latin square design with the 8 diets and 4 periods. Each experimental period consisted of 5-d adaptation and 2-d ileal digesta collection periods. Data for Exp. 1 and 2 were pooled as a 2 × 7 factorial treatment arrangement with the effects of species (i.e., broiler chickens or pigs) and autoclaving time (i.e., 0 to 180 min). The basal endogenous losses of most AA in growing pigs were greater (P < 0.05) compared with broiler chickens. The SID of nitrogen and tryptophan in MBM linearly decreased (P < 0.05) in both species with increasing autoclaving time. An interaction between species and quadratic effect of autoclaving time was observed (P < 0.05) in SID of arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, and valine in MBM. Specifically, the SID of lysine both linearly and quadratically decreased (P < 0.05) in broiler chickens (85.0 to 56.0%), whereas the SID of lysine only linearly decreased (P < 0.05) in growing pigs (79.5 to 46.7%) as autoclaving time increased. In conclusion, given the species differences in amino acid digestibility response to the severity of heat damage, target species should be considered when using amino acid digestibility value of MBM in diet formulation.

Responses of soil aggregation and aggregate‐associated nitrogen to straw return in China: Evidence from a meta‐analysis and a pot experiment

AbstractEnhancing soil structure and soil nitrogen availability is the key to sustainable agricultural development in global cropping systems. Straw return can affect soil aggregation, but the results of recent studies on the influence of straw return on soil aggregation are not consistent, and the distribution and availability of straw‐derived nitrogen in soils are still unclear. Here, a meta‐analysis of the effects of straw return on soil aggregation was conducted based on 57 studies published in China over the past 10 years. Moreover, combined with a pot experiment, the distribution and transfer characteristics of the two main wheat (Triticum aestivum L.)‐preceding crops, corn (Zea mays L.) and soybean (Glycine max L.) straw‐derived nitrogen in the soils were studied by using the 15N‐tracer method in the main wheat‐producing areas of China. 15N‐labeled straw was introduced into soils in pots at rates of 0.3% and 0.5% of the soil dry mass and incubated 60%–70% of the field water capacity throughout the entire growth period of wheat (220 days). A meta‐analysis revealed that straw return significantly improved the mass ratio of large macro‐aggregates (LM%) and small macro‐aggregates (SM%) but significantly decreased the mass ratio of micro‐aggregates (MI%) and silt plus clay‐size particles (CS%), with mean effect sizes of 36.27%, 9.06%, −8.26%, and −21.32%, respectively. The mean weight diameter (MWD) and geometric mean diameter (GMD) also increased by 21.48% and 15.64%, respectively. Compared with SM%, LM% made a greater contribution to the stability of soil aggregates. Moreover, only LM% showed a significant positive correlation with the corresponding aggregate‐associated nitrogen content, which was an important reason for the improvement in soil nitrogen availability after straw return. The positive effect of straw return on soil aggregation was greatest when the soil pH was close to 6.5–7.5, the average annual temperature was greater than 15°C, and the average annual rainfall was close to 800–1000 mm. The results of the pot experiment revealed that the proportions of straw‐derived nitrogen in >2 mm aggregates were 1.21–1.28, 1.50–2.23, and 1.34–1.74 times greater than those in 0.25–2, 0.053–0.25, and <0.053 mm aggregates, respectively. Moreover, the proportion of straw‐derived nitrogen content of aggregates of different particle sizes showed that the proportion of straw used to reach 0.5% of the soil dry weight was greater than 0.3%, which was 1.09–1.66 times greater, and that of soybean straw was significantly greater than that of corn straw, which was 1.50–2.28 times greater. At application rates of 60 g pot−1 and 100 g pot−1 straw, the absorption of soybean straw‐derived nitrogen by wheat was 1.83 and 2.15 times greater than that of corn straw‐derived nitrogen, respectively. In conclusion, straw return effectively improved soil aggregate stability and nitrogen availability, which was closely related to the increase in soil LM%. Soybean straw can stabilize soil aggregates better than corn straw, and its straw‐derived nitrogen is an important nitrogen source for subsequent wheat crops.

Complex nitrogen sources from agro-industrial byproducts: impact on production, multi-stress tolerance, virulence, and quality of Beauveria bassiana blastospores.

Biological control through entomopathogenic fungi provides essential ecological services in the integrated management of agricultural pests. In the context of submerged liquid fermentation, the nutritional composition significantly influences the ecological fitness, virulence and quality of these fungi. This study specifically explores the impact of various complex organic nitrogen sources derived from agro-industrial byproducts on the submerged liquid fermentation of Beauveria bassiana, a versatile entomopathogenic fungus known for producing hydrophilic yeast-like blastospores. Notably, manipulating the nitrogen source during submerged cultivation can influence the quality, fitness, and performance of blastospores. This research identifies cottonseed flour as the optimal low-cost nitrogen source, contributing to increased production yields, enhanced multi-stress tolerance, heightened virulence with extended shelf life and long-term bioactivity. These findings deepen our understanding of the critical role of nitrogen compound selection in liquid media formulation, facilitating the production of ecologically fit and virulent blastospores for more effective pest biocontrol programs.

Generation of New Synthons for Synthesis Through Activation of Nitromethane.

Nitromethane is used a common solvent, stabilizer, and fuel additive. Nitromethane has also been used as a sustainable building block and convenient reagent in chemical synthesis. In this Minireview, we summarize the recent advances in activation of nitromethane, using nitromethane as the source of cyano group, nitrogen, methylamine, formyl group, C1, nitroso, and oxime.

Copper recovery from waste printed circuit boards using pyrite as the bioleaching substrate.

Waste printed circuit boards (WPCBs) can be bioleached for Cu recovery, but lack of substrate for the bioleaching culture. In this study, using pyrite as a bacterial substrate for bioleaching WPCBs and recovering Cu was explored. The results showed that the WPCBs bioleaching using pyrite as the bacterial substrate was feasible. Mechanical crushing was a suitable WPCBs pretreatment method. The optimal WPCBs and pyrite pulp densities were respectively found to be 1.25% (w/v) and 1.0% (w/v), and the suitable nitrogen source ratio ((NH4)2SO4: (NH4)2HPO4) was deemed as 2g/L: 2g/L, achieving a Cu2+ leaching efficiency of 95.60 ± 1.57% in 14 d. Copper in the bioleaching solution can be directly recovery via electrodeposition. The Cu recovery efficiency in 60min was up to 92.19 ± 1.35% under the optimal condition that the initial Cu2+ concentration and pH were respectively set at 7.34g/L and 2.75, and the current density was set at 200 A/m2. Copper was found as the dominant metal in the cathode deposits, existing in the form of Cu and Cu2O. This work provided a novel approach for bioleaching WPCBs and recovering Cu.

Statistical Experimental Designs for cLTB-Syn Vaccine Production Using Daucus carota Cell Suspension Cultures.

The carrot-made LTB-Syn antigen (cLTB-Syn) is a vaccine candidate against synucleinopathies based on carrot cells expressing the target antigen LTB and syn epitopes. Therefore, the development of an efficient production process is required with media culture optimization to increase the production yields as the main goal. In this study, the effect of two nitrogen sources (urea and glutamate) on callus cultures producing cLTB-Syn was studied, observing that the addition of 17 mM urea to MS medium favored the biomass yield. To optimize the MS media composition, the influence of seven medium components on biomass and cLTB-Syn production was first evaluated by a Plackett-Burman design (PBD). Then, three factors were further analyzed using a central composite design (CCD) and response surface methodology (RSM). The results showed a 1.2-fold improvement in biomass, and a 4.5-fold improvement in cLTB-Syn production was achieved at the shake-flask scale. At the bioreactor scale, there was a 1.5-fold increase in biomass and a 2.8-fold increase in cLTB-Syn yield compared with the standard MS medium. Moreover, the cLTB-Syn vaccine induced humoral responses in BALB/c mice subjected to either oral or subcutaneous immunization. Therefore, cLTB-Syn is a promising vaccine candidate that will aid in developing immunotherapeutic strategies to combat PD and other neurodegenerative diseases without the need for cold storage, making it a financially viable option for massive immunization.

Simulating the land use change effects on non-point source pollution in the Duliujian River Basin.

The uncertainty in the generation and formation of non-point source pollution makes it challenging to monitor and control this type of pollution. The SWAT model is frequently used to simulate non-point source pollution in watersheds and is mainly applied to natural watersheds that are less affected by human activities. This study focuses on the Duliujian River Basin (Xiqing section), which is characterized by a dense population and rapid urbanization. Based on the calibrated SWAT model, this study analyzed the effects of land use change on non-point source pollution both temporally and spatially. It was found that nitrogen and phosphorus non-point source pollution load losses were closely related to land use type, with agricultural land and high-density urban land (including rural settlements) being the main contributors to riverine nitrogen and phosphorus pollution. This indicates the necessity of analyzing the impact of land use changes on non-point source pollution loads by identifying critical source areas and altering the land use types that contribute heavily to pollution in these areas. The simulation results of land use type changes in these critical source areas showed that the reduction effect on non-point source pollution load is in the order of forest land > grassland > low-density residential area. To effectively curb surface source pollution in the study area, strategies such as modifying urban land use types, increasing vegetation cover and ground infiltration rate, and strictly controlling the discharge of domestic waste and sewage from urban areas can be implemented.

Endogenous ureides are employed as a carbon source in Arabidopsis plants exposed to carbon starvation conditions.

Ureides, the degraded products of purine catabolism in Arabidopsis, have been shown to act as antioxidant and nitrogen sources. Herein we elucidate purine degraded metabolites as a carbon source using the Arabidopsis Atxdh1, Ataln, and Ataah knockout (KO) mutants vis-à-vis wild-type (WT) plants. Plants were grown under short-day conditions on agar plates containing half-strength MS medium with or without 1% sucrose. Notably, the absence of sucrose led to diminished biomass accumulation in both shoot and root tissues of the Atxdh1, Ataln, and Ataah mutants, while no such effect was observed in WT plants. Moreover, the application of sucrose resulted in a reduction of purine degradation metabolite levels, specifically xanthine and allantoin, predominantly within the roots of WT plants. Remarkably, an increase in proteins associated with the purine degradation pathway was observed in WT plants in the presence of sucrose. Lower glyoxylate levels in the roots but not in the shoot of the Atxdh1 mutant in comparison to WT, were observed under sucrose limitation, and improved by sucrose application in root, indicating that purine degradation provided glyoxylate in the root. Furthermore, the deficit of purine-degraded metabolites in the roots of mutants subjected to carbon starvation was partially mitigated through allantoin application. Collectively, these findings signify that under conditions of sucrose limitation and short-day growth, purines are primarily remobilized within the root system to augment the availability of ureides, serving as an additional carbon (as well as nitrogen) source to support plant growth.

Conversion behavior of heterotrophic nitrification - aerobic denitrification bacterium Paracoccus denitrificans HY-1 in nitrogen and phosphorus removal

The heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria harbored remarkable removal capacity in eliminating single nitrogen pollutant, but their comprehensive performance in dealing with mixed nitrogen sources remained unknown. In this study, the denitrification capacity of HN-AD bacteria Paracoccus denitrificans HY-1 was explored through whole-genome sequencing and nitrogen metabolic pathway analysis, and the complex nitrogen sources with gradient concentration were used to validate its nitrogen removal efficiency under both aerobic and anaerobic conditions. The results demonstrated that strain HY-1 harbored an efficient degradation capacity on three nitrogen sources, and the removal rates of NH4+-N, NO2−-N and NO3−-N were 10.67 mg·L−1·h−1, 27.81 mg·L−1·h−1, and 22.05 mg·L−1·h−1, respectively. The denitrification rate of 15.33 mg·L−1·h−1 was obtained under anaerobic condition with mixed nitrogen sources. Also, the simultaneous nitrification denitrification phosphorus removal (SNDPR) trial revealed that strain HY-1 could eliminate PO43−-P with a rate of 0.38 mg·L−1·h−1 under coexistence condition of the three nitrogen sources. Combined with the nitrogen balance analysis, the results indicated that strain HY-1 possesses a great potential for application in complex nitrogen and phosphorus contaminated environments.

Efficient β-carotene production in engineered Saccharomyces cerevisiae using simple sugars and agricultural waste-based carbon and nitrogen sources.

β-carotene, a precursor to vitamin A, holds significant promise for health and nutrition applications. This study introduces an optimized approach for β-carotene production in Saccharomyces cerevisiae, leveraging metabolic engineering and a novel use of agricultural waste. The GAL80 gene deletion facilitated efficient β-carotene synthesis from sucrose, avoiding the costly galactose induction, and achieved titers up to 727.8 ± 68.0 mg/L with content levels of 71.8 ± 0.4 mg/g dry cell weight (DCW). Furthermore, the application of agricultural by-products, specifically molasses and fish meal as carbon and nitrogen sources, was investigated. This approach yielded a substantial β-carotene titer of 354.9 ± 8.2 mg/L and a content of 60.5 ± 4.3 mg/g DCW, showcasing the potential of these sustainable substrates for industrial-scale production. This study sets a new benchmark for cost-effective, green manufacturing of vital nutrients, demonstrating a scalable, eco-friendly alternative for β-carotene production.

Iron ion detection and life cycle assessment of cutting fluid based on photoluminescent nitrogen-doped carbon quantum dots

Cutting fluid (CF) ensures machining accuracy and improves tool life in machining, which is of great significance for its impurity content detection and life cycle evaluation. In this paper, citric acid and arginine were used as carbon and nitrogen sources, photoluminescent (PL) nitrogen-doped carbon quantum dots (N-CDs) with a particle size ranging from 8 to 14 nm and well dispersion in water-based CF were synthesized by a one-pot hydrothermal reaction method. The N-CDs have the best signal under 360 nm ultraviolet light excitation, which well avoids the autofluorescence of the CF. The N-CDs dispersion have good selectivity and linearity in the Fe3+ concentration range of 2 to 80 μM, and the detection limit is 1.2 μM. The N-CDs were used to detect the concentration of Fe3+ in CF with different working hours, and the results were consistent with the results of coupled plasma emission spectroscopy. This study provides an intelligent sensing platform for the highly sensitive and selective detection of Fe3+ in the CF environment, and provides a promising strategy for the evaluation of the CF lifetime.

Histological validation of in-vivo larvicidal efficacy of marine Streptomyces sp. RD06 secondary metabolites against filariasis causing Culex quinquefasciatus and statistical media optimization for larvicidal derivatives production

Mosquito-borne disease pandemics, such as the Zika virus and chikungunya, have escalated cognizance of how critical it is to implement proficient mosquito vector control measures. The prevention of Culicidae is becoming more difficult these days because of the expeditious imminence of synthetic pesticide resistance and the universal expansion of tremendously invasive mosquito vectors. The present study highlights the insecticidal and larvicidal efficacy of the prospective novel actinobacterium derived from the marine Streptomyces sp. RD06 secondary metabolites against Culex quinquefasciatus mosquito. The pupicidal activity of Streptomyces sp. RD06 showed LC50=199.22±11.54 and LC90= 591.84 ±55.41 against the pupa. The purified bioactive metabolites 1, 2-Benzenedicarboxylic acid, diheptyl ester from Streptomyces sp. RD06 exhibited an LC50 value of 154.13±10.50 and an LC90 value of 642.84±74.61 tested against Cx. quinquefasciatus larvae. The Streptomyces sp. RD06 secondary metabolites exhibited 100 % non-hatchability at 62.5 ppm, and 82 % of hatchability was observed at 250 ppm. In addition, media optimization showed that the highest biomass production was attained at a temperature of 41.44°C, pH 9.23, nitrogen source 11.43 mg/ml, and carbon source 150 mg/ml. Compared to control larvae, the histology and confocal microscopy results showed destruction to the anal gill, lumen content, and epithelial layer residues in the treated larvae. Utilizing an eco-friendly method, these alternative inventive insecticidal derivatives from Streptomyces sp. RD06 eradicates Culex quinquefasciatus. This study highlights the promising potential of these Streptomyces sp. RD06 secondary metabolites to develop affordable and efficacious mosquito larvicides to replace synthetic insecticides in the future.

Flexible and crosslinking electrospun porous carbon nanofiber membranes as freestanding binder-free anodes for lithium-ion batteries

Electrospinning carbon nanofibers with one-dimensional nanostructures have enormous potential for electronic applications owing to their flexibility, electrical conductivity, high surface area and attractive structure. In this paper, porous nitrogen-doped carbon nanofiber membranes with chemical crosslinking structure (PNCNMs-CC) were prepared for lithium-ion batteries anodes by crosslinking treatment and carbonization process using polyimide as precursor, melamine as nitrogen source and ethyl orthosilicate as pore-forming agent. The heightened nitrogen content synergizes with the augmented specific surface area, engendering a striking electrochemical enhancement. Rich pore structure provides more active sites. When utilized as a binder-free, current collector-free anode, PNCNMs-CC shows an excellent rate performance and long cycle stability. The first discharge specific capacity of PNCNMs-CC delivered 710 mAh g−1 at 50 mA g−1. After 1000 cycles at a high current density of 1 A g−1, PNCNMs-CC shows 88 % capacity retention, demonstrating a promising candidate as the flexible anodes for high-performance energy storage devices.

Characterizing the impact of reservoir storage and discharge on nitrogen dynamics in an upstream wetland using a δ15N and δ18O dual-isotope approach

The identification of nitrate sources in reservoir water is important for watershed-scale surface pollution management. Significant fluctuations in river water levels arising from reservoir storage and discharge influence nitrate sources and transport processes. The Sanmenxia Reservoir, in the middle reaches of the Yellow River in China, undergoes significant water level changes (290–316 m), altering the composition of the nitrogen sources. This study employed a δ15N and δ18O dual-isotope method and MixSIAR modeling to quantify the contributions of nitrate sources. This reveals the impact of reservoir water impoundment and discharge on nitrogen dynamics in the upstream region of the wetland and the model sensitivity for each nitrate source. The results showed that the average concentrations of nitrate‑nitrogen (NO- 3-N) were elevated during the impoundment period compared to the discharge period. Nitrogen sources exhibited varying proportions in surface water, groundwater, and soil water during both the impoundment and discharge periods. The predominant sources include manure and sewage (MS), with a maximum proportion of 57.4 % in surface water. Soil nitrogen (SN) accounted for 25.8 % of groundwater nitrogen and 32.1 % of soil water nitrogen during the impoundment period, whereas, during the discharge period, soil nitrogen made up 41.4 % of surface water nitrogen, manure and sewage contributed 44.8 % of groundwater nitrogen, and manure and sewage dominated with 56.7 % of soil water nitrogen. Sensitivity analysis of the MixSIAR model revealed that the isotopic composition of the manure and sewage primary source most significantly influenced the apportionment results of the riverine nitrate source. Reservoir discharge facilitates the dissimilatory nitrate reduction to ammonium (DNRA). The migration of NO- 3 from surface water to soil water and groundwater occurred from the impoundment period to the discharge period.

Adsorption of tetracycline by nitrogen-enriched biochar prepared at different pyrolysis temperatures: Considering the crucial role of nitrogen configuration

Nitrogen atom doping is widely employed to prepare efficient adsorbents to handle target pollutants thanks to its similarity in radius to carbon atoms and excellent functionality. In this study, three types of nitrogen-enriched biochars (NBCs) were prepared to use the corn straw as the raw material and melamine as the nitrogen source by pyrolyzing at 700, 800, and 900 °C (named 700NBC, 800NBC and 900NBC), which were used to remove tetracycline (TC) from water. Results showed that the 900NBC exhibited the highest specific surface area (324.29 m2/g) as well as the maximum adsorption capacity (194.42mg/g) for TC, compared to 800NBC (176.44mg/g) and 700NBC (163.32mg/g). What’s more, the adsorption kinetics and adsorption isotherms were well-fitted by the pseudo-second-order and Langmuir models, indicating that for the adsorption of TC by NBCs, monolayer adsorption and chemisorption were dominant. Specifically, the excellent adsorption performance of NBCs for TC was mostly attributed to the pore filling, hydrogen bonding, π-π interactions, Lewis acid-base interactions, and electrostatic interactions. Importantly, the graphitic N serves as the primary TC adsorption site, followed by pyridinic N. This study would provide new insight into the impact of nitrogen configuration on the adsorption mechanism of NBCs for TC.

Life cycle greenhouse gas emission analysis of co-processing of algal bio-oil and vacuum gas oil in an existing refinery

The co-processing of algal bio-oil and vacuum gas oil (VGO) within existing refineries to generate gasoline and diesel represents a financially advantageous strategy for the integration of third-generation biofuels. Microalgae cultivation can be facilitated through the utilization of algal turf scrubbers (ATS) and open raceway ponds (ORP), with algal bio-oil extraction achievable via hydrothermal liquefaction (HTL) and fast pyrolysis (FP). Four distinct algal bio-oil production processes, namely ORP&HTL, ORP&FP, ATS&FP, and ATS&HTL, have been identified for the integration of algae cultivation and algal bio-oil production. To assess the global warming potential (GWP) of the five co-processing scenarios, the four algal bio-oils co-processed with VGO, along with pure VGO cracking, underwent evaluation utilizing the CML 2001 method. The investigation revealed that the ORP&HTL scenario exhibited the lowest GWP among the five scenarios. In the ORP scenarios, KNO3 and Ca(H2PO4)2·CaHPO4 were utilized as nitrogen (N) and phosphorus (P) sources during the algae production stage, resulting in a GWP 3.86 and 2.01 times higher than that observed in the ATS scenarios during this phase. Subsequent sensitivity analysis demonstrated that optimizing the reduction of GWP entails diminishing electricity and nutrient consumption within the algal production processes, alongside augmenting the proportion of algal bio-oil in the feed. This strategic approach effectively mitigates the GWP associated with the co-processing endeavor.

Winter monsoon brings substantial terrestrial aerosols to Bay of Bengal and adjacent Indian Ocean: Insights from carbon and nitrogen isotopes

It has been currently recognized that air pollutants (e.g., carbon and nitrogen) from South and Southeast Asia have a significant impact on the coastal waters of the northern Indian Ocean. However, the understanding of the dynamics and fates of these pollutants in aerosols to the remote ocean through long-distance transportation still needs to be improved. To address this issue, stable isotopic compositions (δ13C, δ15N) of total carbon (TC) and nitrogen (TN) and other geochemical indexes in aerosols are investigated over the Bay of Bengal (BOB) and the adjacent Indian Ocean during the winter monsoon period. The concentrations of TN, TC and aerosol nutrients exhibited a decreasing trend from the northern BOB (N-BOB) to the southern BOB (S-BOB) and Indian Ocean, reflecting the weakening trend of polluted continental influence from the N-BOB to the ocean. The high concentrations of TC (4.28-18.21 μg m-3) in the aerosols of the N-BOB are mainly influenced by the emissions of coal combustion (68±21%), while the high concentrations of TN (0.69-7.31 μg m-3) in the N-BOB are mainly from biofuel/biomass burning (52±31%). In the S-BOB, the lower concentrations of TC (1.42-2.98 μg m-3) and TN (0.38-2.03 μg m-3) mainly originated from the formation of secondary aerosols and the changes in aerosol chemical composition during long-distance transportation from the continent. The primary marine source was responsible for the low TC and TN concentrations over the Indian Ocean. This study quantifies the nitrogen and carbon source shifts from continental anthropogenic activities in the N-BOB to dominant marine and photochemical transformation sources in the S-BOB and the adjacent Indian Ocean, quantitatively deepening the understanding of the impact of terrestrial aerosols on the ocean.