Microfluidic-oriented synthesis of enriched iridium nanodots/carbon architecture for robust electrocatalytic nitrogen fixation

Electrocatalytic nitrogen reduction reaction(NRR)is considered as a promising candidate to achieve ammonia synthesis because of clean electric energy,moderate reaction condition,safe operating process and harmless by-products.However,the chemical inertness of nitrogen and poor activated capacity on catalyst surface usually produce low ammonia yield and faradic efficiency.Herein,the microfluidic technology is proposed to efficiently fabricate enriched iridium nanodots/carbon architecture.Owing to in-situ co-precipitation reaction and microfluidic manipulation,the iridium nanodots/carbon nanomaterials possess small average size,uniform dispersion,high conductivity and abundant active sites,producing good proton activation and rapid electrons transmission and moderate adsorption/desorption capacity.As a result,the as-prepared iridium nanodots/carbon nanomaterials realize large ammonia yield of 28.73 μg h^(-1) cm^(-2) and faradic efficiency of 9.14%in KOH solution.Moreover,the high ammonia yield of 11.21 μg h^(-1) cm^(-2) and faradic efficiency of 24.30%are also achieved in H_(2)SO_(4) solution.The microfluidic method provides a reference for large-scale fabrication of nano-sized catalyst materials,which may accelerate the progress of electrocatalytic NRR in industrialization field.

Increased dependence on nitrogen-fixation of a native legume in competition with an invasive plant

Suppression of roots and/or their symbiotic microorganisms,such as mycorrhizal fungi and rhizobia,is an effective way for alien plants to outcompete native plants.However,little is known about how invasive and native plants interact with the quantity and activity of nutrient-acquisition agents.Here a pot experiment was conducted with monoculture and mixed plantings of an invasive plant,Xanthium strumarium,and a common native legume,Glycine max.We measured traits related to root and nodule quantity and activity and mycorrhizal colonization.Compared to the monoculture,fine root quantity(biomass,surface area)and activity(root nitrogen(N)concentration,acid phosphatase activity)of G.max decreased in mixed plantings;nodule quantity(biomass)decreased by 45%,while nodule activity in Nfixing via rhizobium increased by 106%;mycorrhizal colonization was unaffected.Contribution of N fixation to leaf N content in G.max increased in the mixed plantings,and this increase was attributed to a decrease in the rhizosphere soil N of G.max in the mixed plantings.Increased root quantity and activity,along with a higher mycorrhizal association was observed in X.strumarium in the mixed compared to monoculture.Together,the invasive plant did not directly scavenge N from nodule-fixed N,but rather depleted the rhizosphere soil N of the legume,thereby stimulating the activity of N-fixation and increasing the dependence of the native legume on this N source.The quantity-activity framework holds promise for future studies on how native legumes respond to alien plant invasions.

Plasma nitrogen fixation system with dual-loop enhancement for improved energy efficiency and its efficacy for lettuce cultivation

Plasma nitrogen fixation(PNF)has been emerging as a promising technology for greenhouse gasfree and renewable energy-based agriculture.Yet,most PNF studies seldom address practical application-specific issues.In this work,we present the development of a compact and automatic PNF system for on-site agricultural applications.The system utilized a gliding-arc discharge as the plasma source and employed a dual-loop design to generate NO_(x)from air and water under atmospheric conditions.Experimental results showed that the system with a dualloop design performs well in terms of energy costs and production rates.Optimal operational parameters for the system were determined through experimentation,resulting in an energy cost of 13.9 MJ mol^(-1)and an energy efficiency of 16 g kWh^(-1)for NO_(3)^(-)production,respectively.Moreover,the concentration of exhausted NO_(x)was below the emission standards.Soilless lettuce cultivation experiments demonstrated that NO_(x)^(-)produced by the PNF system could serve as liquid nitrate nitrogen fertilizer.Overall,our work demonstrates the potential of the developed PNF system for on-site application in the production of green-leaf vegetables.

Facile preparation of Ag_(2)S/KTa_(0.5)Nb_(0.5)O_(3) heterojunction for enhanced performance in catalytic nitrogen fixation via photocatalysis and piezo-photocatalysis

In this work, a novel heterojunction composite Ag_(2)S/KTa_(x)Nb_(1-x)O_(3)was designed and synthesized through a combination of hydrothermal and precipitation procedures. The Ta/Nb ratio of the KTa_(x)Nb_(1-x)O_(3)and the Ag_(2)S content were optimized. The best 0.5% Ag_(2)S/KTa_(0.5)Nb_(0.5)O_(3)(KTN) sample presents an enhanced photocatalytic performance in ammonia synthesis than KTN and Ag_(2)S. Under simulated sunlight, the NH_(3)generation rate of 0.5% Ag_(2)S/KTN reaches 2.0 times that of pure KTN. Under visible light, the reaction rate ratio of the two catalysts is 6.0.XRD, XPS, and TEM analysis revealed that Ag2S was intimately decorated on the KTN nanocubes surface, which promoted the electron transfer between the two semiconductors. The band structure investigation indicated that the Ag_(2)S/KTN heterojunction established a type-Ⅱ band alignment with intimate contact, thus realizing the effective transfer and separation of photogenerated carriers. The change in charge separation was considered as the main reason for the enhanced photocatalytic performance. Interestingly, the Ag_(2)S/KTN composite exhibited higher NH3generation performance under the combined action of ultrasonic vibration and simulated sunlight. The enhanced piezo-photocatalytic performance can be ascribed that the piezoelectric effect of KTN improved the bulk separation of charge carriers in KTN. This study not only provides a potential catalyst for photocatalytic nitrogen fixation but also shows new ideas for the design of highly efficient catalysts via semiconductor modification and external field coupling.

Oxygen defect modulating the charge behavior in titanium dioxide for boosting photocatalytic nitrogen fixation performance

Extremely high-temperature and high-pressure requirement of Haber-Bosch process motivates the search for a sustainable ammonia synthesis approach under mild conditions.Photocatalytic technology is a potential solution to convert N2 to ammonia.However,the poor light absorption and low charge carrier separation efficiency in conventional semiconductors are bottlenecks for the application of this technology.Herein,a facile synthesis of anatase TiO_(2)nanosheets with an abundance of surface oxygen vacancies(TiO_(2)-OV)via the calcination treatment was reported.Photocatalytic experiments of the prepared anatase TiO_(2)samples showed that TiO_(2)-OV nanosheets exhibited remarkably increased ammonia yield for solar-driven N2 fixation in pure water,without adding any sacrificial agents.EPR,XPS,XRD,UV-Vis DRS,TEM,Raman,and PL techniques were employed to systematically explore the possible enhanced mechanism.Studies revealed that the introduced surface oxygen vacancies significantly extended the light absorption capability in the visible region,decreased the adsorption and activation barriers of inert N2,and improved the separation and transfer efficiency of the photogenerated electronhole pairs.Thus,a high rate of ammonia evolution in TiO_(2)-OV was realized.This work offers a promising and sustainable approach for the efficient artificial photosynthesis of ammonia.

Strategies to achieve effective nitrogen activation

Ammonia serves as a crucial chemical raw material and hydrogen energy carrier.Aqueous electrocatalytic nitrogen reduction reaction(NRR),powered by renewable energy,has attracted tremendous interest during the past few years.Although some achievements have been revealed in aqueous NRR,significant challenges have also been identified.The activity and selectivity are fundamentally limited by nitrogen activation and competitive hydrogen evolution.This review focuses on the hurdles of nitrogen activation and delves into complementary strategies,including materials design and system optimization(reactor,electrolyte,and mediator).Then,it introduces advanced interdisciplinary technologies that have recently emerged for nitrogen activation using high-energy physics such as plasma and triboelectrification.With a better understanding of the corresponding reaction mechanisms in the coming years,these technologies have the potential to be extended in further applications.This review provides further insight into the reaction mechanisms of selectivity and stability of different reaction systems.We then recommend a rigorous and detailed protocol for investigating NRR performance and also highlight several potential research directions in this exciting field,coupling with advanced interdisciplinary applications,in situ/operando characterizations,and theoretical calculations.

Optimized nitrogen application methods to improve nitrogen use efficiency and nodule nitrogen fixation in a maize-soybean relay intercropping system

In China, the abuse of chemical nitrogen （N） fertilizer results in decreasing N use efficiency （NUE）, wasting resources and causing serious environmental problems. Cereal-legume intercropping is widely used to enhance crop yield and improve resource use efficiency, especially in Southwest China. To optimize N utilization and increase grain yield, we conducted a two-year field experiment with single-factor randomized block designs of a maize-soybean intercropping system （IMS）. Three N rates, NN （no nitrogen application）, LN （lower N application： 270 kg N ha-1）, and CN （conventional N application： 330 kg N ha-1）, and three topdressing distances of LN （LND）, e.g., 15 cm （LND1）, 30 cm （LND2） and 45 cm （LND3） from maize rows were evaluated. At the beginning seed stage （R5）, the leghemoglobin content and nitrogenase activity of LND3 were 1.86 mg plant-1 and 0.14 mL h-1 plant-1, and those of LND1 and LND2 were increased by 31.4 and 24.5%, 6.4 and 32.9% compared with LND3, respectively. The ureide content and N accumulation of soybean organs in LND1 and LND2 were higher than those of LND3. The N uptake, NUE and N agronomy efficiency （NAE） of IMS under CN were 308.3 kg ha-1, 28.5%, and 5.7 kg grain kg-1 N, respectively; however, those of LN were significantly increased by 12.4, 72.5, and 51.6% compared with CN, respectively. The total yield in LND1 and LND2 was increased by 12.3 and 8.3% compared with CN, respectively. Those results suggested that LN with distances of 15-30 cm from the topdressing strip to the maize row was optimal in maize-soybean intercropping. Lower N input with an optimized fertilization location for IMS increased N fixation and N use efficiency without decreasing grain yield.

Nitrogen acquisition,fixation and transfer in maize/alfalfa intercrops are increased through root contact and morphological responses to interspecies competition

Nitrogen(N)fixation by legumes and nitrogen transfer to cereals have been considered as important pathways for overyielding and higher N use efficiency in cereal/legume intercropping systems.However,the extent to which root morphology contributes to N fixation and transfer is unclear.A two-factorial greenhouse experiment was conducted to quantify the N fixation,transfer and root morphology characteristics of the maize/alfalfa intercropping system in two consecutive years using the 15N-urea leaf labeling method,and combining two N levels with three root separation techniques.N application could inhibit N fixation and transfer in a maize/alfalfa intercropping system.Irrespective of the N application level,compared with plastic sheet separation(PSS),no separation(NS)and nylon mesh separation(NNS)significantly increased the total biomass(36%)and total N content(28%),while the N fixation rate also sharply increased by 75 to 134%,and the amount of N transferred with no root barrier was 1.24–1.42 times greater than that with a mesh barrier.Redundancy analysis(RDA)showed that the crown root dry weight(CRDW)of maize and lateral root number(LRN)of alfalfa showed the strongest associations with N fixation and transfer.Our results highlight the importance of root contact for the enhancement of N fixation and transfer via changes in root morphology in maize/alfalfa intercropping systems,and the overyielding system was achieved via increases in maize growth,at the cost of smaller decreases in alfalfa biomass production.

Construction of 2D/2D Z-scheme MnO_(2-x)/g-C_(3)N_(4) photocatalyst for efficient nitrogen fixation to ammonia

Reducing nitrogen to ammonia with solar energy has become a wide concern when it comes to photocatalysis research.It is considered to be one of the more promising alternate options for the conventional Haber-Bosch cycle.Herein,2D g-C_(3)N_(4)composites with modifying ultrathin sheet MnO_(2-x)were prepared and used as nitrogen fixation photocatalyst.With the assistance of the nature of MnO_(2-x),the generation rate of NH_(3)reached 225 mmol g^(-1)h^(-1),which is more than twice over the rate of pristine 2D g-C_(3)N_(4)(107 mmol g^(-1)h^(-1)).The presence of ultrathin sheet MnO_(2-x)shortens the gap of the carriers to the surface of photocatalyst.Thus the speed of electron transfer gets increased.Besides,the construction of Z-scheme heterojunction boosts the separation and migration of photogenerated carriers.As a result,the nitrogen reduction reaction(NRR)performance gets enhanced.The work may provide an example of promoting the NRR performance of non-metallic compound.

Influences of frequency on nitrogen fixation of dielectric barrier discharge in air

The influences of frequency on nitrogen fixation of dielectric barrier discharge in air were studied by electrical diagnostics, gas detection and infrared detection methods. The system power, nitrogen oxide concentration, voltage-current waveform, dielectric surface temperature distribution and filamentous discharge pictures were measured, and then the energy yield was calculated; paper studied their changing tendencies in the presence of frequency. Results show that frequency has strong influences on nitrogen fixation. When the parameters of reaction chamber and amplitude of applied voltage is fixed, with the increasing of frequency, the system power increases; in 5-10 kHz, nitrogen oxide gas concentration up to 1113.7 mg m-3, and 7 kHz is the optimal nitrogen fixation frequency whose energy yield is 20.5 mR （m3 W）-1.

Effect of nitrogen fertilization on yield, N content, and nitrogen fixation of alfalfa and smooth bromegrass grown alone or in mixture in greenhouse pots

Planting grass and legume mixtures on improved grasslands has the potential advantage of realizing both higher yields and lower environmental pollution by optimizing the balance between applied N fertilizer and the natural process of legume biological nitrogen fixation. However, the optimal level of N fertilization for grass-legume mixtures, to obtain the highest yield, quality, and contribution of N2 fixation, varies with species. A greenhouse pot experiment was conducted to study the temporal dynamics of N2 fixation of alfalfa （Medicago sativa L.） grown alone and in mixture with smooth bromegrass （Bromus inermis Leyss.） in response to the addition of fertilizer N. Three levels of N （0, 75, and 150 kg ha-1） were examined using 15N-labeled urea to evaluate N2 fixation via the 15N isotope dilution method. Treatments were designated NO （0.001 g per pot）, N75 （1.07 g per pot） and N150 （2.14 g per pot）. Alfalfa grown alone did not benefit from the addition of fertilizer N; dry matter was not significantly increased. In contrast, dry weight and N content of smooth bromegrass grown alone was increased significantly by N application. When grown as a mixture, smooth bromegrass biomass was increased significantly by N application, resulted in a decrease in alfalfa biomass. In addition, individual alfalfa plant dry weight （shoots＋roots） was significantly lower in the mixture than when grown alone at all N levels. Smooth bromegrass shoot and root dry weight were significantly higher when grown with alfalfa than when grown alone, regardless of N application level. When grown alone, alfalfa＇s N2 fixation was reduced with N fertilization （R2=0.9376,P=0.0057）. When grown in a mixture with smooth bromegrass, with 75 kg ha-1 of N fertilizer, the percentage of atmospheric N2 fixation contribution to total N in alfalfa （%Ndfa） had a maximum of 84.07 and 83.05% in the 2nd and 3rd harvests, respectively. Total 3-harvest %Ndfa was higher when alfalfa was grown in a mixture than when grown alone （shoots： ｜t｜=3.39, P=0.0096; root： ｜t｜=3.57, P=0.0073）. We believe this was due to smooth bromegrass being better able to absorb available soil N （due to its fibrous root system）, resulting inlower soil N availability and allowing alfalfa to develop an effective N2 fixing symbiosis prior to the 1st harvest. Once soil N levels were depleted, alfalfa was able to fix N2, resulting in the majority of its tissue N being derived from biological nitrogen fixation （BNF） in the 2nd and 3rd harvests. When grown in a mixture, with added N, alfalfa established an effective symbiosis earlier than when grown alone; in monoculture BNF did not contribute a significant portion of plant N in the N75 and N150 treatments, whereas in the mixture, BNF contributed 17.90 and 16.28% for these treatments respectively. Alfalfa has a higher BNF efficiency when grown in a mixture, initiating BNF earlier, and having higher N2 fixation due to less inhibition by soil-available N. For the greatest N-use-efficiency and sustainable production, grass-legume mixtures are recommended for imDrovino orasslands, usino a moderate amount of N fertilizer （75 kq N ha-l） to provide optimum benefits.

Preliminary study of an open-air water-contacting discharge for direct nitrogen fixation

Efficient nitrogen fixation through a reactive plasma process attracts intense interest due to the environmental issues induced by the conventional Haber–Bosch method. In this work, we present a direct and simple fixation routine without any catalysts for nitrogen in open air using an atmospheric-pressure pin-to-solution plasma electrolytic system. Nitrate, nitrite, and ammonia as the nitrogen-derived chemicals in solution were analyzed as indicators under various discharge conditions to estimate the energy efficiency of this process. The results show that the nitrogen fixation process was much more efficient by the pin-positive discharge compared to the negative one. N chemicals preferred to be formed when the solution was of negative polarity. It was also found that, with the help of solution circulation, the energy efficiency was enhanced compared to that of static liquid. However, an inverse trend was observed with the increase of the discharge current. Further study by optical emission spectroscopy indicates the important roles of active N2* and water vapour and their derived species near the plasma–water interface in the fixation process.

Nitrogen Fixation into HNO_3 and HNO_2 by Pulsed High Voltage Discharge

Plasma processing induced by discharge offers a unique way to activate nitrogen molecules. Direct nitrogen fixation into water can be realized through this approach. In this study, air or pure nitrogen gas was used as the major nitrogen source bubbled into the discharge reactor. When a discharge occurred, nitrogen was dissociated to active species to take part in the aqueous chemical process. HNO3 and HNO2 were produced. The nitrogen fixation process was influenced distinctly by the presence of hydroxyl radicals. During a discharge of 21 min, HNO3 was the main product and occupied 95% of the total nitrogen content in water. Its concentration was 1.36 × 10^-3 mol/L^-1 with bubbling air and was 1.53 × 10^-3 mol L^-1 with bubbling nitrogen, while the yield was 2.32 × 10^-3 mol J^-1S^-1 and 2.06 × 10^-8 mol J^-1S^-1, respectively.

Boron Nitride Quantum Dots/Ti_(3)C_(2)T_(x)-MXene Heterostructure For Efficient Electrocatalytic Nitrogen Fixation

Electrocatalytic N_(2) fixation through N_(2) reduction reaction(NRR)has been regarded as a promising route for sustainable NH_(3) synthesis,while exploring high-performing NRR catalysts is pivotal yet challenging.Herein,BN quantum dots/Ti_(3)C_(2)T_(x)-MXene(BNQDs/Ti_(3)C_(2)T_(x))heterostructure is demonstrated as an efficient and durable NRR catalyst,exhibiting a high NH_(3) yield of 52.8±3.3μg h^(-1) mg^(-1) with an FE of 19.1±1.6%at0.4 V(vs.RHE),which stand at the high level among all reported BN-and MXene-based NRR catalysts.Theoretical computations reveal that the electronic interactions between BNQDs and Ti_(3)C_(2)T_(x) enrich the electron density of B atoms at the heterointerface and endow them with enhanced electron-donating capability for N_(2) activation and protonation.Meanwhile,the decorated BNQDs can block the active sites of Ti_(3)C_(2)T_(x) for hydrogen evolution,rendering a high N_(2)-to-NH_(3) selectivity.

Low-Density Co-Inoculation with Bradyrhizobium japonicum SAY3-7 and Streptomyces griseoflavus P4 Promotes Plant Growth and Nitrogen Fixation in Soybean Cultivars

Inoculation density has a marked effect on nodulation and N fixation in soybean (Glycine max L.). Therefore, we conducted this study to determine the optimal inoculation density of Bradyhizobium japonicum SAY3-7 (SAY3-7) and Streptomyces griseoflavus P4 (P4) for plant growth, nodulation, and N fixation, and to investigate the effect of co-inoculation on selected soybean cultivars, using the optimal inoculation density. Nitrogen fixation, in terms of an acetylene reduction activity value, was measured using a flame ionization gas chromatograph. In this study, low-density single inoculation with P4 (105 or 106 cells mL-1) was associated with the highest plant biomass, compared with normal- and high-density single inoculation with P4 (107 or 108 cells mL-1). Moreover, low-density single or co-inoculations with SAY3-7 and/or P4 produced the highest nodule biomass and highest nitrogenase activity, compared with single or dual inoculation at other inoculation densities. Therefore, we evaluated low-density co-inoculation with P4 and SAY3-7, at the rate of 105 cells mL-1, on selected soybean cultivars. Low-density co-inoculation increased the plant biomass, compared with un-inoculated plants. The effects of single and co-inoculation on nodulation did not differ significantly for any of the cultivars, except “Yezin-9” in the first experiment and “Shan Seine” in the second experiment. Low-density inoculation with both bacteria increased N fixation by 15% - 75% for seven of the cultivars in the first experiment and by 15% - 39% for three of the cultivars in the second experiment, compared with single inoculation with SAY3-7. Based on the overall results, we concluded that low-density co-inoculation with P4 and SAY3-7 gave improved plant growth and N fixation.

“Biological Nitrogen Fixation” Book Summary

Biological nitrogen fixation is a very valuable alternative to nitrogen fertilizer. This process will be discussed in the “Biological Nitrogen Fixation” book. A wide array of free-living and associative nitrogen fixing organisms (diazotrophs) will be covered. The most extensively studied and applied example of biological nitrogen fixation is the symbiotic interaction between nitrogen fixing “rhizobia” and legume plants. While legumes are important as major food and feed crops, cereals such as wheat, maize and rice are the primary food crops, but do not have this symbiotic nitrogen fixing interaction with rhizobia. It has thus been a “holy grail” to transfer the ability to fix nitrogen to the cereals and this topic will be also addressed in these books.

A new trick on an old support: Zr in situ defects-created carbon nitride for efficient electrochemical nitrogen fixation

Electrochemical nitrogen reduction reaction(NRR) to produce ammonia under ambient conditions is considered as a promising approach to tackle the energy-intensive Haber-Bosch process,but the low Faradaic efficiency and yield of NH_3 are still a challenge.Herein,a carbon-vacancies enriched mesoporous g-C_3 N_4 is developed by an in situ Zr doping strategy.The in situ mesoporous-forming mechanism is deeply understood by TPSR to reveal the functions of Zr dopant that pulls C from the precursor of C_3 N_4,resulting the formation of homogeneous mesopores with about 57% of the one C-defective s-triazine ring in C_3 N_4.Due to the defect sites obtained in metal doping synthesis,the RuAu bimetallic supported catalyst(RuAu_3/0.3 Zr-C_3 N_4) exhibits effective NRR performance with a Faraday efficiency of 11.54% and an NH_3 yield of 5.28 μg h^(-1) mg_(cat) ^(-1).at-0.1 V(RHE),which is nearly 10 times higher than that of RuAu_3/C_3 N_4 catalyst.This work proposes a simple and template-free preparation method for the high defect density mesoporous C_3 N_4,and provides new possibilities of a wide application of mesopore g-C3 N4.

Dinitrogen fixation mediated by lanthanum hydride

Dinitrogen fixation is one of the key reactions in chemistry, which is closely associated with food, environment, and energy. It has been recently recognized that the hydride materials containing negatively charged hydrogen(H~-) show promises for Nfixation and hydrogenation to ammonia. Herein, we report that rare earth metal hydrides such as lanthanum hydride can also fix Neither by heating to 200 °C or ball milling under ambient Npressure and temperature. The Nfixation by lanthanum hydride may proceed via an intermediate lanthanum hydride-nitride(La-H-N) structure to form the final lanthanum nitride product. The hydride ion functions as an electron donor, which provides electrons for Nactivation possibly mediated by the lanthanum atoms. It is observed that N–H bond is not formed during the Nfixation process, which is distinctly different from the alkali or alkaline earth metal hydrides. The hydrolysis of La-H-N to ammonia is feasible using water as the hydrogen source. These results provide new insights into the nitrogen fixation by hydride materials and more efforts are needed for the development of rare earth metal-based catalysts and/or nitrogen carriers for ammonia synthesis processes.

Nitrogen fixation driven by mesoscale eddies and the Kuroshio Current in the northern South China Sea and the East China Sea

N2 fixation rates(NFR,in terms of N)in the northern South China Sea(nSCS)and the East China Sea(ECS)were measured using the acetylene reduction assay in summer and winter,2009.NFR of the surface water ranged from 1.14 nmol/(L·d)to 10.40 nmol/(L·d)(average at(4.89±3.46)nmol/(L·d),n=11)in summer and 0.74 nmol/(L·d)to 29.45 nmol/(L·d)(average at(7.81±8.50)nmol/(L·d),n=15)in winter.Significant spatio-temporal heterogeneity emerged in our study:the anticyclonic eddies(AE)(P<0.01)and the Kuroshio Current(KC)(P<0.05)performed significantly higher NFR than that in the cyclonic eddies or no-eddy area(CEONE),indicating NFR was profoundly influenced by the physical process of the Kuroshio and mesoscale eddies.The depth-integrated N2 fixation rates(INF,in terms of N)ranged from 52.4μmol/(m2·d)to 905.2μmol/(m2·d)(average at(428.9±305.5)μmol/(m2·d),n=15)in the winter.The contribution of surface NFR to primary production(PP)ranged from 1.7%to 18.5%in the summer,and the mean contribution of INF to new primary production(NPP)in the nSCS and ECS were estimated to be 11.0%and 36.7%in the winter.The contribution of INF to NPP(3.0%–93.9%)also decreased from oligotrophic sea toward the eutrophic waters affected by runoffs or the CEONE.Furthermore,we observed higher contributions compared to previous studies,revealing the vital roles of nitrogen fixation in sustaining the carbon pump of the nSCS and ECS.

Surface BrØnsted-Lewis dual acid sites for high-efficiency dinitrogen photofixation in pure water

As is known to all, nitrogen not only plays an important role in the industrial development of human society but also plays an important part in the proteins that constitute the essence of life[1]. In 1910, the Haber-Bosch process was first used to synthesize ammonia.