The Arno River Basin(Central Italy)is affected by a considerable anthropogenic pressure due to the presence of large cities and widespread industrial and agricultural practices.In this work,26 water samples from the A...The Arno River Basin(Central Italy)is affected by a considerable anthropogenic pressure due to the presence of large cities and widespread industrial and agricultural practices.In this work,26 water samples from the Arno River and its main tributaries were analyzed to assess the water pollution status.The geochemical composition of the Arno River changes from the source(dominated by a Ca-HCO_(3) facies)to the mouth(where a Na-Cl(SO4)chemistry prevails)with an increasing quality deterioration,as suggested by the Chemical Water Quality Index,due to anthropogenic contributions and seawater intrusion before flowing into the Ligurian Sea.The Ombrone and Usciana tributaries introduce anthropogenic pollutants into the Arno River,whilst Elsa tributary supplies significant contents of geogenic sulfate.The concentrations of dissolved nitrate and nitrite(up to 63 and 9 mg/L,respectively)and the respective isotopic values of𝛿15N and𝛿18O were also determined to understand origin and fate of the N-species in the Arno River Basin surface waters.The combined application of𝛿15N-NO_(3) and𝛿18O-NO_(3) and N-source apportionment modelling allowed the identification of soil organic nitrogen and sewage and domestic wastes as primary sources for dissolved NO_(3)-.The𝛿15N-NO_(2) and𝛿18O-NO_(2) values suggest that the nitrification process affects the ARB waters,thus controlling the abundances and proportion of the N-species.Our work indicates that additional efforts are needed to improve management strategies to reduce the release of nitrogenated species to the surface waters of the Arno River Basin,since little progress has been made from the early 2000s.展开更多
Ammonium toxicity in plants remains poorly understood despite extensive research.While nitrate is known to benefit plant growth,the synergistic effects of nitrate in mitigating ammonium toxicity,even at low concentrat...Ammonium toxicity in plants remains poorly understood despite extensive research.While nitrate is known to benefit plant growth,the synergistic effects of nitrate in mitigating ammonium toxicity,even at low concentrations,are not fully elucidated.This review delves into the physiological and molecular nature of this phenomenon.To date,nitrate-dependent alleviation of ammonium toxicity is the result of cumulative consequences of the role of nitrate as a nutrient and signal in plant performance.The ability to counteract the ammonium-induced acidification through nitrate uptake and metabolism,the enhancement of potassium uptake as an essential nitrate counterion,and the nitratedependent signaling of key factors involved in ammonium assimilation,ROS scavenging,and growth hormone biosynthesis,are the most relevant hallmarks.In addition,evidence suggests that the availability of nitrate and ammonium has driven ecological selection in plants,determining current N preferences,and may have led to the selection of nitrate-dependent and ammonium-sensitive domesticated crops and the inefficient use of N fertilizers in agriculture.As ammonium toxicity limits N fertilization options and reduces agricultural yields,when it could be a more sustainable and cheaper alternative to nitrate,this review provides a better understanding of how plants use nitrate to counteract the problematic aspects of ammonium nutrition.展开更多
Accelerated industrialization combined with over-applied nitrogen fertilizers results in serious nitrate pollution insurface and ground water,disrupting the balance of the global nitrogen cycle.Electrochemical nitrate...Accelerated industrialization combined with over-applied nitrogen fertilizers results in serious nitrate pollution insurface and ground water,disrupting the balance of the global nitrogen cycle.Electrochemical nitrate reduction(eNO_(3)RR)emerges as an attractive strategy to simultaneously enable nitrate removal and decentralized ammo-nia fabrication,restoring the globally perturbed nitrogen cycle.However,complex deoxygenation-hydrogenationprocesses and sluggish proton-electron transfer kinetics significantly hinder practical application of eNO_(3)RR.In this study,we developed carbon-coated Cu-Ni bimetallic catalysts derived from metal-organic frameworks(MOFs)to facilitate eNO_(3)RR.The unique structural features of catalyst promote enhanced synergy between Cuand Ni,effectively addressing critical challenges in nitrate reduction.Comprehensive structural and electrochem-ical analysis demonstrate that electrochemical nitrate-to-nitrite conversion mainly takes place on active Cu sites,the introduction of Ni could efficiently accelerate the generation of aquatic active hydrogen,promoting the hy-drogenation of oxynitrides during eNO_(3)RR.In addition,Ni introduction could push up the d-band center of thecatalyst,thus enhancing the adsorption and activation of nitrate and the corresponding intermediates.Detailedreaction pathways for nitrate-to-ammonia conversion are illuminated by rotating disk electrode(RDE),in-situFourier-transform infrared spectroscopy,in-situ Raman spectrum and electrochemical impedance spectroscopy(EIS).Benefiting from the synergistic effect of Cu and Ni,optimum catalyst exhibited excellent nitrate reductionperformance.This work provides a new idea for elucidating the underlying eNO_(3)RR reaction mechanisms andcontributes a promising strategy for designing efficient bimetallic electrocatalysts.展开更多
To address the deficiencies in comprehensive surface contamination prevention strategies within China's nitrate-affected regions,this research innovatively proposes the DITAPH model-a systematic framework integrat...To address the deficiencies in comprehensive surface contamination prevention strategies within China's nitrate-affected regions,this research innovatively proposes the DITAPH model-a systematic framework integrating groundwater nitrate vulnerability assessment and Nitrate Vulnerable Zones(NVZs)delineation through optimization of hydrogeological parameters.Based on detailed hydrogeological and hydrochemical investigations,the DITAPH model was applied in the plain areas of Quanzhou to evaluate its applicability.The model selected hydrogeological parameters(depth of groundwater,lithology of the vadose zone,topographic slope,aquifer water yield property),one climatic parameter(precipitation),and two anthropogenic parameters(land use type and population density)as assessment indicators.The results of the groundwater nitrate vulnerability assessment showed that the low,relatively low,relatively high,and high groundwater nitrate vulnerability zones in the study area accounted for 5.96%,35.44%,53.74%and 4.86%of the total area,respectively.Groundwater nitrate vulnerability was most strongly influenced by human activities,followed by groundwater depth and topographic slope.The high vulnerability zone is mainly affected by domestic and industrial wastewater,whereas the relatively high groundwater nitrate vulnerability zone is primarily influenced by agricultural activities.Validation of the DITAPH model revealed a significant positive correlation between the DITAPH index(DI)and nitrate concentration(ρ(NO3−)).The results of the NVZs delineated by the DITAPH model are reliable and can serve as a tool for water resource management planning,guiding the development of targeted measures in the NVZs to prevent groundwater contamination.展开更多
Electrocatalytic nitrate-to-ammonia conversion offers dual environmental and sustainable synthesis benefits,but achieving high efficiency with low-cost catalysts remains a major challenge.This review focuses on cobalt...Electrocatalytic nitrate-to-ammonia conversion offers dual environmental and sustainable synthesis benefits,but achieving high efficiency with low-cost catalysts remains a major challenge.This review focuses on cobalt-based electrocatalysts,emphasizing their structural engineering for enhanced the performance of electrocatalytic nitrate reduction reaction(NO3RR)through dimensional control,compositional tuning,and coordination microenvironment modulation.Notably,by critically analyzing metallic cobalt,cobalt alloys,cobalt compounds,cobalt single atom and molecular catalyst configurations,we firstly establish correlations between atomic-scale structural features and catalytic performance in a coordination environment perspective for NO3RR,including the dynamic reconstruction during operation and its impact on active site.Synergizing experimental breakthroughs with computational modeling,we decode mechanisms underlying competitive hydrogen evolution suppression,intermediate adsorption-energy optimization,and durability enhancement in complex aqueous environments.The development of cobalt-based catalysts was summarized and prospected,and the emerging opportunities of machine learning in accelerating the research and development of high-performance catalysts and the configuration of series reactors for scalable nitrate-to-ammonia systems were also introduced.Bridging surface science and applications,it outlines a framework for designing multifunctional electrocatalysts to restore nitrogen cycle balance sustainably.展开更多
Lithium metal batteries(LMBs)have been regarded as one of the most promising alternatives in the post-lithium battery era due to their high energy density,which meets the needs of light-weight electronic devices and l...Lithium metal batteries(LMBs)have been regarded as one of the most promising alternatives in the post-lithium battery era due to their high energy density,which meets the needs of light-weight electronic devices and long-range electric vehicles.However,technical barriers such as dendrite growth and poor Li plating/stripping reversibility severely hinder the practical application of LMBs.However,lithium nitrate(LiNO_(3))is found to be able to stabilize the Li/electrolyte interface and has been used to address the above challenges.To date,considerable research efforts have been devoted toward understanding the roles of LiNO_(3) in regulating the surface properties of Li anodes and toward the development of many effective strategies.These research efforts are partially mentioned in some articles on LMBs and yet have not been reviewed systematically.To fill this gap,we discuss the recent advances in fundamental and technological research on LiNO_(3) and its derivatives for improving the performances of LMBs,particularly for Li-sulfur(S),Li-oxygen(O),and Li-Li-containing transition-metal oxide(LTMO)batteries,as well as LiNO_(3)-containing recipes for precursors in battery materials and interphase fabrication.This review pays attention to the effects of LiNO_(3) in lithium-based batteries,aiming to provide scientific guidance for the optimization of electrode/electrolyte interfaces and enrich the design of advanced LMBs.展开更多
Nitrogen(N)is the most important nutrient for plants;however,microbe-mediated N transformation under different N forms is unclear.This experiment investigated the effects of four treatments fertilized with various N f...Nitrogen(N)is the most important nutrient for plants;however,microbe-mediated N transformation under different N forms is unclear.This experiment investigated the effects of four treatments fertilized with various N forms,no N(control,CK),100%ammonium N(AN),100%nitrate N(NN),and 50%ammonium N+50%nitrate N(ANNN),on soil chemical properties,rhizosphere bacterial network,and rice growth.The ANNN treatment enhanced soil pH by 6.9%,soil organic carbon by 12%,and microbial biomass N(MBN)by 60%compared to CK.The linear discriminant effect size(LEfSe)analysis indicated four highly abundant biomarkers of bacterial communities each in the CK,NN,and AN treatments,while the ANNN treatment showed six highly abundant biomarkers with maximum effect size and linear discriminant analysis(LDA)score>4.The 16S rRNA gene-predicted functions under PICRUST indicated glutathione metabolism and proteasome and Tax4Fun recorded amino acid metabolism in the ANNN treatment.The combination of ammonium and nitrate N(i.e.,the ANNN treatment)significantly increased the expression levels of the genes encoding N metabolism,including AMT1,NRT2.1,GS1,and GOGAT1,and induced 39%,27%,35%,and 38%increase in nitrate reductase,nitrite reductase,glutamine synthetase,and glutamate synthase,respectively,in comparison to CK.In addition,the ANNN treatment promoted rice leaf photosynthetic rate by 37%,transpiration rate by 41%,CO_(2) exchange rate by 11%,and stomatal conductance by 18%compared to CK,while increased N use efficiency(NUE)by 10%and 19%,respectively,compared to the AN and NN treatments.These findings suggest that the combination of ammonium and nitrate N can promote bacterial community abundance,composition,and functional pathways by improving soil properties and can increase NUE and rice growth.This study provides a theoretical basis for the rational application of N fertilizers and the implications of this approach for future sustainable crop production.展开更多
Utilizing nitrate(NO_(3)^(-))as the nitrogen source to produce ammonia can effectively remove NO_(3)^(-)pollutant while obtaining valuable ammonia,and the understanding of the mechanisms is essential for the design of...Utilizing nitrate(NO_(3)^(-))as the nitrogen source to produce ammonia can effectively remove NO_(3)^(-)pollutant while obtaining valuable ammonia,and the understanding of the mechanisms is essential for the design of new catalysts.In this work,by using density functional theory calculations,the electroreduction mechanisms of nitrate reduction reaction(NO_(3)RR)on transition metal single atom supported on 3N-coordinated N-doped graphene(TM/N_(3)-G)are systematically investigated.It is found that the protonation of ^(*)OH acts as the potential determing steps except for the traditionally considered ^(*)NO_(3)/^(*)NO/^(*)NO_(2) protonation step and the desorption of water may play an important role for NO_(3)RR on some TM/N_(3)-G.By considering the stability of single-atom catalyst(SAC),the preferential adsorption of NO_(3)^(-)larger than H and H_(2)O,the limiting potential of whole NO_(3)RR,the selectivity toward NH3,V(Mn,Os)/pyrrolic-N_(3)-G and Mn(Ru,Ir)/pyridinic-N_(3)-G are screened out as potential SACs for NO_(3)RR.This work provides an understanding of the NO_(3)RR mechanism and highlights several promising NO_(3)RR catalysts based on the TM/N_(3)-G system.展开更多
Nitrate synthesis is an important process for agriculture and industry,but suffers from energy-intensive steps including the synthesis and subsequent oxidation of ammonia.Herein,we present a selective N_(2)transformat...Nitrate synthesis is an important process for agriculture and industry,but suffers from energy-intensive steps including the synthesis and subsequent oxidation of ammonia.Herein,we present a selective N_(2)transformation to nitrate by guiding the charge neutralization of self-electrified water microdroplets in an artificial cloud generated with the portable ultrasonic atomizer.The electron and ion transfer in the charge neutralization of water microdroplets on metal micromesh enables an up to~40-fold increase in the reactivity of nitrate formation reaction driven by ultrasonic energy.A robust semi-continuous N_(2)oxidation by a Ni-mesh-screened cloud system was achieved,providing nitrate with~12 mM concentration every 20 h.These findings emphasize the potential of harnessing the microdroplet-mediated cloud electrochemistry of N_(2)in decentralizing the current mass production of fertilizer.展开更多
Ordinary high nitrogen fertilizer often results in nitrate (NO3--N) leaching and low recovery. Microplot and field plot experiments were conducted to determine the effect of controlled release nitrogen fertilizer (CRN...Ordinary high nitrogen fertilizer often results in nitrate (NO3--N) leaching and low recovery. Microplot and field plot experiments were conducted to determine the effect of controlled release nitrogen fertilizer (CRNF) on reco very and nitrate leaching on paddy soils. During two early rice cropping seasons (2002 and 2003), a single basal application of CRNF at 90 kg N ha-1 increased grain yields by 7.7%to 11.6%compared with two applications of urea. Estimated by the difference method fertilizer N recovery of CRNF (mean 76.3%) was 38.9 pe rcentage point higher than that of urea (mean 37.4%); estimated by 15N isotope method (mean 49.6%) CRNF (mean 67.1%) was 35.9 percentage point higher than ur ea (mean 31.2%). NO3--N leaching losses were 9.19 and 6.70 kg ha-1 for urea and CRNF, respectively. NO3--N leaching during the early rice cropping season was 27.1 %lower from CRNF than from two applications of urea. These losses repr esent 10.2%and 7.4%of applied urea-N and CRNF-N. Results from this study ind icate that CRNF improves N recovery and reduces NO3--N leaching and increases rice yield.展开更多
[Objective] The aim was to investigate effect of intercropping and nitrogen regulation on nitrate and apparent loss of nitrogen, providing theoretical references for reasonable fertilization and pollution reduction. [...[Objective] The aim was to investigate effect of intercropping and nitrogen regulation on nitrate and apparent loss of nitrogen, providing theoretical references for reasonable fertilization and pollution reduction. [Method] In the research, deeprooted eggplants and shallow-rooted scallions were intercropped with nitrogen regulat- ed to study on effect of the cropping system on temporal and spatial changes of ni- trate nitrogen and apparent loss of nitrogen. [Result] When the fertilizers were re- duced, contents of nitrate were less in intercropped field than that in mono-cropped one, indicating that eluviation of nitrate would be blocked and nitrate accumulation would be lowered effectively by intercropped eggplants and scallions. With intercrop- ping adopted, the reduced fertilizers would lower nitrate content in soil, deep soil in particular, and nitrate was significantly lower than that fertilized with conventional quantity during vegetable growth period. In addition, nitrate accumulation in soil profiles was also significantly shorter in field applied with reduced fertilizers than that with conventional one. It was shown that intercropping and fertilizer reduction would both cut apparent loss of nitrate down in varying degrees. [Conclusion] The research lays basis for high production of vegetables, reasonable fertilization and pollution reduction.展开更多
Lateral root is primary organ for plant to explore and utilize soil nutrient efficiently. The development of lateral roots (LR) is controlled by both genetic factors and nutrient status in environment. To investigate ...Lateral root is primary organ for plant to explore and utilize soil nutrient efficiently. The development of lateral roots (LR) is controlled by both genetic factors and nutrient status in environment. To investigate the effects of nitrate (NO3-) on rice lateral root growth and nitrogen (N) uptake efficiency under upland condition, three treatments, including root-split culture and whole plant culture in N sufficient and deficient conditions, were used in a vermiculite culture experiment. Root-split treatment showed that the growth of lateral roots was stimulated by localized nitrate supply. However, in whole plant culture, elongation of lateral roots was induced by NO3- deficiency. The effects of NO3- on rice lateral root growth were genotype-dependent. Similar N concentration, soluble sugar concentration and N content in shoot were observed in both root-split treatment and whole plant culture under NO3- sufficient condition, suggesting that the nitrogen requirement for rice normal growth could be satisfied with only half of roots supplied with NO3-. In the root-split treatment, N uptake was positively correlated with the average of lateral root length (ALRL) in NO3--supplied side, suggesting that the ALRL is important for rice root N uptake in the environment where the nitrogen nutrient is limiting factor. No significant correlation was observed between N uptake and ALRL in whole plant culture under N sufficient condition, which implies that the length of lateral roots may not be the main factor to determine tire rice root N uptake in nutrient-rich zone. Morphological and metabolic evidence in this study provided some prospects for genetic improvement of root system characters to improve the efficiency of nutrient absorption in rice.展开更多
ObjectiveThe aim was to explore the movement of nitrate nitrogen in tall-fescue soils by different kinds of slow release nitrogen fertilizers. MethodBased on infiltration-tanks and test plots, a new and environment fr...ObjectiveThe aim was to explore the movement of nitrate nitrogen in tall-fescue soils by different kinds of slow release nitrogen fertilizers. MethodBased on infiltration-tanks and test plots, a new and environment friendly fertilizer was explored. ResultThe results show that compared with urea treatment, slow-release nitrogen fertilizer treatments could reduce nitrate nitrogen content and leaching amount in soils. Compared with PCU30 and IU treatments, the PCU60 treatment became more efficient in reducing nitrate content and leaching amount in 0-90 cm soil layer. ConclusionIn summary, slow-release nitrogen fertilizer, which can reduce soil nitrate content and leaching losses, is a kind of novel fertilizer with high environmental benefit and promising application.展开更多
The contents of nitrate nitrogen（NO-3-N） in underground water from typical planting areas in Liao river basin were analyzed, so as to provide theoretical basis for rational fertilization and effectively prevent the ...The contents of nitrate nitrogen（NO-3-N） in underground water from typical planting areas in Liao river basin were analyzed, so as to provide theoretical basis for rational fertilization and effectively prevent the NO-3-N content from exceeding standard. The results showed that difference of the contents of NO-3-N in groundwater from different typical planting areas was significant. The highest content of NO-3-N in underground water was 37.4 mg/L from flower-growing region, then 22. 3 mg/L from maize-growing region, 21.9 mg/L from vegetable-growing region, and the lowest content of NO-3-N in underground water was 19.2 mg/L from rice-growing region. Except rice-growing region, the contents of NO-3-N in underground water of the samples in all planting areas were exceeding standard limit; potential health risk still existed in rice-growing region. Accordingly 12.5%-87.5%, 9.4%-75.5%, 17.9%-58.9% and 21.4%-96.0% of the samples were exceeding standard limit in maize growing region, rice-growing region, vegetable-growing region and flower-growing region. The contents of NO-3-N in under-groundwater before the rainy season was higher than that of NO-3-N in under-groundwater after the rainy season at the same depth of the well.展开更多
The moving dynamics of nitrate nitrogen（NO3-N）in soil of maize field on meadow soil of Daling river valley in Liaoning and its rational fertilization controlling were discussed in this study by the designing of diff...The moving dynamics of nitrate nitrogen（NO3-N）in soil of maize field on meadow soil of Daling river valley in Liaoning and its rational fertilization controlling were discussed in this study by the designing of different kinds of N application methods.The results showed that the content of NO3-N in soil was increased with the amount of nitrogen fertilizer;At the same amount of nitrogen fertilizer,the content of NO3-N in soil showed a trend of chemical fertilizerstraw treatmentslow controlled release fertilizer.Based on the requirement of roots in different growth stages to nutrition,the migration directions of NO3-N could be regulated by each layer of soil.In the early growth stage,the NO3-N would move upward,while it moved downward in the late growth stage.Straw returning treatment could improve the keeping ability of soil to NO3-N and avoid the downward migration of NO3-N,as well as reduce the damage of groundwater pollution.The use of slow controlled release fertilizer had achieved the continuing releasing of nutrition.Moreover,the peak of nutrition releasing had been delayed for 30 d,which had met the requirement of nutrient supply in maturing stage.The yield of slow controlled release fertilizer treatment was the highest with the least accumulation of NO3-N and less negative influence on environment.The yield of straw returning treatment and chemical fertilizer treatment was closed to each other.展开更多
The nitrate nitrogen removal efficiency of iron-carbon micro-electrolysis system was discussed in treating pharmaceutical wastewater with high nitrogen and refractory organic concentration. The results show that the g...The nitrate nitrogen removal efficiency of iron-carbon micro-electrolysis system was discussed in treating pharmaceutical wastewater with high nitrogen and refractory organic concentration. The results show that the granularity of fillings,pH,volume ratios of iron-carbon and gas-water,and HRT. have significant effects on the nitrogen removal efficiency of iron-carbon micro-electrolysis system. The iron-carbon micro-electrolysis system has a good removal efficiency of pharmaceutical wastewater with high nitrogen and refractory organic concentration when the influent TN,NH4+-N,NO3--N and BOD5/CODCr are 823 mg/L,30 mg/L,793 mg/L and 0.1,respectively,at the granularity of iron and carbon 0.425 mm,pH 3,iron-carbon ratio 3,gas-water ratio 5,HRT 1.5 h,and the removal rates of TN,NH4+-N and NO3--N achieve 51.5%,70% and 50.94%,respectively.展开更多
Ammonium(NH+4) is the main nitrogen(N) form for rice crops, while NH+4near the root surface can be oxidized to nitrate(NO-3)by NH+4-oxidizing bacteria. Nitrate can be accumulated within rice tissues and reused when N ...Ammonium(NH+4) is the main nitrogen(N) form for rice crops, while NH+4near the root surface can be oxidized to nitrate(NO-3)by NH+4-oxidizing bacteria. Nitrate can be accumulated within rice tissues and reused when N supply is insufficient. We compared the remobilization of NO-3stored in the tissue and vacuolar between two rice(Oryza sativa L.) cultivars, Yangdao 6(YD6, indica)with a high N use efficiency(NUE) and Wuyujing 3(WYJ3, japonica) with a low NUE and measured the uptake of NO-3, expression of nitrate reductase(NR), NO-3transporter genes(NRTs), and NR activity after 4 d of N starvation following 7-d cultivation in a solution containing 2.86 mmol L-1NO-3. The results showed that both tissue NO-3concentration and vacuolar NO-3activity were higher in YD6 than WYJ3 under N starvation. YD6 showed a 2- to 3-fold higher expression of OsNRT2.1 in roots on the 1st and 4th day of N starvation and had significantly higher values of NO-3uptake(maximum uptake velocity, Vmax) than the cultivar WYJ3.Furthermore, YD6 had significantly higher leaf and root maximum NR activity(NRAmax) and actual NR activity(NRAact) as well as stronger root expression of the two NR genes after the 1st day of N starvation. There were no significant differences in NRAmax and NRAact between the two rice cultivars on the 4th day of N starvation. The results suggested that YD6 had stronger NRA under N starvation, which might result in better NO-3re-utilization from the vacuole, and higher capacity for NO-3uptake and use, potentially explaining the higher NUE of YD6 compared with WYJ3.展开更多
Rice is being increasingly cultivated in intermittently irrigated regions and also in aerobic soil in which Nitrate （NO3^- ） plays important role in nutrition of plant. However, there is no information regarding the...Rice is being increasingly cultivated in intermittently irrigated regions and also in aerobic soil in which Nitrate （NO3^- ） plays important role in nutrition of plant. However, there is no information regarding the influence of nitrate on the overall growth and uptake of nitrogen （N） in rice plant. Solution culture experiments were carried out to study the effects of NO^3- on the plant growth, uptake of N, and uptake kinetics of NH4^＋ in four typical rice （Oryza sativa L.） cultivars （conventional indica, conventional japonica, hybrid indica, and hybrid japonica）, and on plasma membrane potential in roots of two conventional rice cultivars （indica and japonica） at the seedling stage. The results obtained indicated that a ratio of 50/50 NH4^＋-N/NO3^--N increased the average biomass of rice shoots and roots by 20% when compared with that of 100/0 NH4^＋-N/NO3^--N. In case of the 50/50 ratio, as compared with the 100/0 ratio, total N accumulated in shoots and roots of rice increased on an average by 42% and 57%, respectively. Conventional indica responds to NO3^- more than any other cultivars that were tested. The NO^3- supply increased the maximum uptake rate （Vmax） of NH4^＋ by rice but did not show any effect on the apparent Michaelis-Menten constant （Km） value, with the average value of Vmax for NH4^＋ among the four cultivars being increased by 31.5% in comparison with those in the absence of NO3^-. This suggested that NO3^- significantly increased the numbers of the ammonium transporters. However, the lack of effect on the Km value also suggested that the presence of NO3^- had no effect on the affinity of the transporters for NH4^＋. The plasma membrane potential in the roots of conventional indica and japonica were greatly increased by the addition of NO3^- , suggesting that NO3^- could improve the uptake of N by roots of the rice plant. In conclusion, the mechanisms by which NO3^- enhances the growth and N uptake of rice plant was found by the increased value of Vmax of NH4^＋ and increased plasma membrane potential. Thus promotion of nitrification in paddy soil is of great significance for improving the production of rice.展开更多
The objective is to study whether the accumulation and utilization of plant N are controlled by Mo status in winter wheat cultivars. Mo-efficient cultivar 97003 （eft） and Mo-inefficient cultivar 97014 （ineff） were...The objective is to study whether the accumulation and utilization of plant N are controlled by Mo status in winter wheat cultivars. Mo-efficient cultivar 97003 （eft） and Mo-inefficient cultivar 97014 （ineff） were grown in severely Mo-deficient acidic soil （Tamm-reagent-extractable Mo 0.112 mg kg^-1） with （＋Mo） and without （-Mo） the application of 0.13 mg kg^-1 Mo. The accumulation and use efficiency of plant total N were significantly higher in ＋Mo than that in -Mo and in eft than that in ineff under Mo deficiency. N use efficiency was remarkably higher in maturity but it was forwarded to jointing stage after Mo supply, thus indicating that Mo supply promoted the N use efficiency besides N uptake and eff was efficient in N uptake and utilization. The overall activity of nitrate reductase （NR, EC 1.6.6.1） was significantly higher in ＋Mo than in -Mo and ratio of ＋Mo/-Mo was even to 14.8 at filleting stage for ineff. Activity of glutamine synthetase （GS, EC 6.3.1.2） was significantly lower in ＋Mo than in -Mo. Concentration of nitrate and glutamate were also significantly lower in ＋Mo than in -Mo, thus provided evidences for enhancing N use efficiency by Mo supply. Activities of NR and GS were significantly higher and concentrations of nitrate and glutamate were significantly lower in eff than ineff under Mo deficiency, thus indicated eff was more efficient in N reduction and utilization. It is therefore concluded that Mo could promote N accumulation and utilization in winter wheat which was directly related to NR and feedback regulated by GS. Higher Mo status also results in higher accumulation and utilization of plant N in eft.展开更多
文摘The Arno River Basin(Central Italy)is affected by a considerable anthropogenic pressure due to the presence of large cities and widespread industrial and agricultural practices.In this work,26 water samples from the Arno River and its main tributaries were analyzed to assess the water pollution status.The geochemical composition of the Arno River changes from the source(dominated by a Ca-HCO_(3) facies)to the mouth(where a Na-Cl(SO4)chemistry prevails)with an increasing quality deterioration,as suggested by the Chemical Water Quality Index,due to anthropogenic contributions and seawater intrusion before flowing into the Ligurian Sea.The Ombrone and Usciana tributaries introduce anthropogenic pollutants into the Arno River,whilst Elsa tributary supplies significant contents of geogenic sulfate.The concentrations of dissolved nitrate and nitrite(up to 63 and 9 mg/L,respectively)and the respective isotopic values of𝛿15N and𝛿18O were also determined to understand origin and fate of the N-species in the Arno River Basin surface waters.The combined application of𝛿15N-NO_(3) and𝛿18O-NO_(3) and N-source apportionment modelling allowed the identification of soil organic nitrogen and sewage and domestic wastes as primary sources for dissolved NO_(3)-.The𝛿15N-NO_(2) and𝛿18O-NO_(2) values suggest that the nitrification process affects the ARB waters,thus controlling the abundances and proportion of the N-species.Our work indicates that additional efforts are needed to improve management strategies to reduce the release of nitrogenated species to the surface waters of the Arno River Basin,since little progress has been made from the early 2000s.
基金supported by an MCIN RyC Programme MCIN/AEI/10.13039/501100011033the‘European Union Next Generation EU/PRTR’under grant no.RYC2021-032345-I+1 种基金supported by the AEI(grant no.PID2019-107463RJ-I00/AEI/10.13039/501100011033)the Regional Research and Development Programme of the Government of Navarre(call 2019,project NitroHealthy,PC068).
文摘Ammonium toxicity in plants remains poorly understood despite extensive research.While nitrate is known to benefit plant growth,the synergistic effects of nitrate in mitigating ammonium toxicity,even at low concentrations,are not fully elucidated.This review delves into the physiological and molecular nature of this phenomenon.To date,nitrate-dependent alleviation of ammonium toxicity is the result of cumulative consequences of the role of nitrate as a nutrient and signal in plant performance.The ability to counteract the ammonium-induced acidification through nitrate uptake and metabolism,the enhancement of potassium uptake as an essential nitrate counterion,and the nitratedependent signaling of key factors involved in ammonium assimilation,ROS scavenging,and growth hormone biosynthesis,are the most relevant hallmarks.In addition,evidence suggests that the availability of nitrate and ammonium has driven ecological selection in plants,determining current N preferences,and may have led to the selection of nitrate-dependent and ammonium-sensitive domesticated crops and the inefficient use of N fertilizers in agriculture.As ammonium toxicity limits N fertilization options and reduces agricultural yields,when it could be a more sustainable and cheaper alternative to nitrate,this review provides a better understanding of how plants use nitrate to counteract the problematic aspects of ammonium nutrition.
基金supported by the Natural Science Foundation of China(No.52101279)the Key Scientific Research Foundation of Education department of Hunan Province(No.24A0003)the Scientific Research Project of Education Department of Hunan Province(No.21B000)and the Fundamental Research Funds for the Central Universities of Central South University.
文摘Accelerated industrialization combined with over-applied nitrogen fertilizers results in serious nitrate pollution insurface and ground water,disrupting the balance of the global nitrogen cycle.Electrochemical nitrate reduction(eNO_(3)RR)emerges as an attractive strategy to simultaneously enable nitrate removal and decentralized ammo-nia fabrication,restoring the globally perturbed nitrogen cycle.However,complex deoxygenation-hydrogenationprocesses and sluggish proton-electron transfer kinetics significantly hinder practical application of eNO_(3)RR.In this study,we developed carbon-coated Cu-Ni bimetallic catalysts derived from metal-organic frameworks(MOFs)to facilitate eNO_(3)RR.The unique structural features of catalyst promote enhanced synergy between Cuand Ni,effectively addressing critical challenges in nitrate reduction.Comprehensive structural and electrochem-ical analysis demonstrate that electrochemical nitrate-to-nitrite conversion mainly takes place on active Cu sites,the introduction of Ni could efficiently accelerate the generation of aquatic active hydrogen,promoting the hy-drogenation of oxynitrides during eNO_(3)RR.In addition,Ni introduction could push up the d-band center of thecatalyst,thus enhancing the adsorption and activation of nitrate and the corresponding intermediates.Detailedreaction pathways for nitrate-to-ammonia conversion are illuminated by rotating disk electrode(RDE),in-situFourier-transform infrared spectroscopy,in-situ Raman spectrum and electrochemical impedance spectroscopy(EIS).Benefiting from the synergistic effect of Cu and Ni,optimum catalyst exhibited excellent nitrate reductionperformance.This work provides a new idea for elucidating the underlying eNO_(3)RR reaction mechanisms andcontributes a promising strategy for designing efficient bimetallic electrocatalysts.
基金supported by the National Key Research and Development Program of China(No.2022YFF1301301)the Natural Science Foundation of Xiamen Municipality(No.3502Z202472047)the Geological Survey Program of China Geological Survey(DD20190303).
文摘To address the deficiencies in comprehensive surface contamination prevention strategies within China's nitrate-affected regions,this research innovatively proposes the DITAPH model-a systematic framework integrating groundwater nitrate vulnerability assessment and Nitrate Vulnerable Zones(NVZs)delineation through optimization of hydrogeological parameters.Based on detailed hydrogeological and hydrochemical investigations,the DITAPH model was applied in the plain areas of Quanzhou to evaluate its applicability.The model selected hydrogeological parameters(depth of groundwater,lithology of the vadose zone,topographic slope,aquifer water yield property),one climatic parameter(precipitation),and two anthropogenic parameters(land use type and population density)as assessment indicators.The results of the groundwater nitrate vulnerability assessment showed that the low,relatively low,relatively high,and high groundwater nitrate vulnerability zones in the study area accounted for 5.96%,35.44%,53.74%and 4.86%of the total area,respectively.Groundwater nitrate vulnerability was most strongly influenced by human activities,followed by groundwater depth and topographic slope.The high vulnerability zone is mainly affected by domestic and industrial wastewater,whereas the relatively high groundwater nitrate vulnerability zone is primarily influenced by agricultural activities.Validation of the DITAPH model revealed a significant positive correlation between the DITAPH index(DI)and nitrate concentration(ρ(NO3−)).The results of the NVZs delineated by the DITAPH model are reliable and can serve as a tool for water resource management planning,guiding the development of targeted measures in the NVZs to prevent groundwater contamination.
基金supported by the National Natural Science Foundation of China(Grant Nos.:21825201,52401244 and 52201227)Henan Province Key Research and Development and Promotion Program(Scientific and Technological Breakthrough Project:232102240088 and 252102230078)+3 种基金the Key Research&Development and Promotion of Special Project(Scientific Problem Tackling)of Henan Province(252102230078)Doctoral Research Startup Fund Project of Henan Open University(BSJH-2025-04)Zhejiang Provincial Natural Science Foundation of China(LQ24B020005,LQ23B030001)China Postdoctoral Science Foundation(2024M762442).
文摘Electrocatalytic nitrate-to-ammonia conversion offers dual environmental and sustainable synthesis benefits,but achieving high efficiency with low-cost catalysts remains a major challenge.This review focuses on cobalt-based electrocatalysts,emphasizing their structural engineering for enhanced the performance of electrocatalytic nitrate reduction reaction(NO3RR)through dimensional control,compositional tuning,and coordination microenvironment modulation.Notably,by critically analyzing metallic cobalt,cobalt alloys,cobalt compounds,cobalt single atom and molecular catalyst configurations,we firstly establish correlations between atomic-scale structural features and catalytic performance in a coordination environment perspective for NO3RR,including the dynamic reconstruction during operation and its impact on active site.Synergizing experimental breakthroughs with computational modeling,we decode mechanisms underlying competitive hydrogen evolution suppression,intermediate adsorption-energy optimization,and durability enhancement in complex aqueous environments.The development of cobalt-based catalysts was summarized and prospected,and the emerging opportunities of machine learning in accelerating the research and development of high-performance catalysts and the configuration of series reactors for scalable nitrate-to-ammonia systems were also introduced.Bridging surface science and applications,it outlines a framework for designing multifunctional electrocatalysts to restore nitrogen cycle balance sustainably.
基金supported by the Yunnan Fundamental Research Projects(Grant Nos.202401AU070163 and 202501AT070298)the Yunnan Engineering Research Center Innovation Ability Construction and Enhancement Projects(Grant No.2023-XMDJ-00617107)+5 种基金the University Service Key Industry Project of Yunnan Province(Grant No.FWCY-ZD2024005)the Expert Workstation Support Project of Yunnan Province(Grant No.202405AF140069)the Scientific Research Foundation of Kunming University of Science and Technology(Grant No.20220122)the Analysis and Test Foundation of Kunming University of Science and Technology(Grant No.2023T20220122)the Natural Science Foundation of Inner Mongolia Autonomous Region of China(Grant No.2025QN02057)the Ordos City Strategic Pioneering Science and Technology Special Program for New Energy(Grant No.DC2400003365).
文摘Lithium metal batteries(LMBs)have been regarded as one of the most promising alternatives in the post-lithium battery era due to their high energy density,which meets the needs of light-weight electronic devices and long-range electric vehicles.However,technical barriers such as dendrite growth and poor Li plating/stripping reversibility severely hinder the practical application of LMBs.However,lithium nitrate(LiNO_(3))is found to be able to stabilize the Li/electrolyte interface and has been used to address the above challenges.To date,considerable research efforts have been devoted toward understanding the roles of LiNO_(3) in regulating the surface properties of Li anodes and toward the development of many effective strategies.These research efforts are partially mentioned in some articles on LMBs and yet have not been reviewed systematically.To fill this gap,we discuss the recent advances in fundamental and technological research on LiNO_(3) and its derivatives for improving the performances of LMBs,particularly for Li-sulfur(S),Li-oxygen(O),and Li-Li-containing transition-metal oxide(LTMO)batteries,as well as LiNO_(3)-containing recipes for precursors in battery materials and interphase fabrication.This review pays attention to the effects of LiNO_(3) in lithium-based batteries,aiming to provide scientific guidance for the optimization of electrode/electrolyte interfaces and enrich the design of advanced LMBs.
基金financially supported by the National Natural Science Foundation of China(No.32172109)the Natural Science Foundation of Guangdong Province,China(No.2021A1515010566).
文摘Nitrogen(N)is the most important nutrient for plants;however,microbe-mediated N transformation under different N forms is unclear.This experiment investigated the effects of four treatments fertilized with various N forms,no N(control,CK),100%ammonium N(AN),100%nitrate N(NN),and 50%ammonium N+50%nitrate N(ANNN),on soil chemical properties,rhizosphere bacterial network,and rice growth.The ANNN treatment enhanced soil pH by 6.9%,soil organic carbon by 12%,and microbial biomass N(MBN)by 60%compared to CK.The linear discriminant effect size(LEfSe)analysis indicated four highly abundant biomarkers of bacterial communities each in the CK,NN,and AN treatments,while the ANNN treatment showed six highly abundant biomarkers with maximum effect size and linear discriminant analysis(LDA)score>4.The 16S rRNA gene-predicted functions under PICRUST indicated glutathione metabolism and proteasome and Tax4Fun recorded amino acid metabolism in the ANNN treatment.The combination of ammonium and nitrate N(i.e.,the ANNN treatment)significantly increased the expression levels of the genes encoding N metabolism,including AMT1,NRT2.1,GS1,and GOGAT1,and induced 39%,27%,35%,and 38%increase in nitrate reductase,nitrite reductase,glutamine synthetase,and glutamate synthase,respectively,in comparison to CK.In addition,the ANNN treatment promoted rice leaf photosynthetic rate by 37%,transpiration rate by 41%,CO_(2) exchange rate by 11%,and stomatal conductance by 18%compared to CK,while increased N use efficiency(NUE)by 10%and 19%,respectively,compared to the AN and NN treatments.These findings suggest that the combination of ammonium and nitrate N can promote bacterial community abundance,composition,and functional pathways by improving soil properties and can increase NUE and rice growth.This study provides a theoretical basis for the rational application of N fertilizers and the implications of this approach for future sustainable crop production.
基金partially supported by the National Natural Science Foundation of China(No.22373092,No.22288201)CAS Project for Young Scientists in Basic Research(YSBR-051)supported by USTC Tang Scholarship。
文摘Utilizing nitrate(NO_(3)^(-))as the nitrogen source to produce ammonia can effectively remove NO_(3)^(-)pollutant while obtaining valuable ammonia,and the understanding of the mechanisms is essential for the design of new catalysts.In this work,by using density functional theory calculations,the electroreduction mechanisms of nitrate reduction reaction(NO_(3)RR)on transition metal single atom supported on 3N-coordinated N-doped graphene(TM/N_(3)-G)are systematically investigated.It is found that the protonation of ^(*)OH acts as the potential determing steps except for the traditionally considered ^(*)NO_(3)/^(*)NO/^(*)NO_(2) protonation step and the desorption of water may play an important role for NO_(3)RR on some TM/N_(3)-G.By considering the stability of single-atom catalyst(SAC),the preferential adsorption of NO_(3)^(-)larger than H and H_(2)O,the limiting potential of whole NO_(3)RR,the selectivity toward NH3,V(Mn,Os)/pyrrolic-N_(3)-G and Mn(Ru,Ir)/pyridinic-N_(3)-G are screened out as potential SACs for NO_(3)RR.This work provides an understanding of the NO_(3)RR mechanism and highlights several promising NO_(3)RR catalysts based on the TM/N_(3)-G system.
基金supported by the National Key R&D Program of China(2022YFA1504603)the National Natural Science Foundation of China(22025206,22172163)+1 种基金the Dalian Innovation Support Plan for High Level Talents(2022RG13)the Fundamental Research Funds for the Central Universities(20720220008)。
文摘Nitrate synthesis is an important process for agriculture and industry,but suffers from energy-intensive steps including the synthesis and subsequent oxidation of ammonia.Herein,we present a selective N_(2)transformation to nitrate by guiding the charge neutralization of self-electrified water microdroplets in an artificial cloud generated with the portable ultrasonic atomizer.The electron and ion transfer in the charge neutralization of water microdroplets on metal micromesh enables an up to~40-fold increase in the reactivity of nitrate formation reaction driven by ultrasonic energy.A robust semi-continuous N_(2)oxidation by a Ni-mesh-screened cloud system was achieved,providing nitrate with~12 mM concentration every 20 h.These findings emphasize the potential of harnessing the microdroplet-mediated cloud electrochemistry of N_(2)in decentralizing the current mass production of fertilizer.
文摘Ordinary high nitrogen fertilizer often results in nitrate (NO3--N) leaching and low recovery. Microplot and field plot experiments were conducted to determine the effect of controlled release nitrogen fertilizer (CRNF) on reco very and nitrate leaching on paddy soils. During two early rice cropping seasons (2002 and 2003), a single basal application of CRNF at 90 kg N ha-1 increased grain yields by 7.7%to 11.6%compared with two applications of urea. Estimated by the difference method fertilizer N recovery of CRNF (mean 76.3%) was 38.9 pe rcentage point higher than that of urea (mean 37.4%); estimated by 15N isotope method (mean 49.6%) CRNF (mean 67.1%) was 35.9 percentage point higher than ur ea (mean 31.2%). NO3--N leaching losses were 9.19 and 6.70 kg ha-1 for urea and CRNF, respectively. NO3--N leaching during the early rice cropping season was 27.1 %lower from CRNF than from two applications of urea. These losses repr esent 10.2%and 7.4%of applied urea-N and CRNF-N. Results from this study ind icate that CRNF improves N recovery and reduces NO3--N leaching and increases rice yield.
基金Supported by"Research on Nitrate Nitrogen Eluviation and Water Adjustment through Intercropping of Vegetables with Different Root Lengths"of Beijing Science and Technology Star Plan(B)(2007B045)"Effects of Fertilizer Sources on Heavy Metals in Soils and Vegetable Quality"of Foundation for Distinguished Scholars in Beijing(D)(2010D002020000004)"Research on Mutation Rules of Key Indices in SoilEnvironment for Tomato with High-production"of Foundation for Youths of Beijing Academy of Agricultural and Forestry Sciences(QN201103)~~
文摘[Objective] The aim was to investigate effect of intercropping and nitrogen regulation on nitrate and apparent loss of nitrogen, providing theoretical references for reasonable fertilization and pollution reduction. [Method] In the research, deeprooted eggplants and shallow-rooted scallions were intercropped with nitrogen regulat- ed to study on effect of the cropping system on temporal and spatial changes of ni- trate nitrogen and apparent loss of nitrogen. [Result] When the fertilizers were re- duced, contents of nitrate were less in intercropped field than that in mono-cropped one, indicating that eluviation of nitrate would be blocked and nitrate accumulation would be lowered effectively by intercropped eggplants and scallions. With intercrop- ping adopted, the reduced fertilizers would lower nitrate content in soil, deep soil in particular, and nitrate was significantly lower than that fertilized with conventional quantity during vegetable growth period. In addition, nitrate accumulation in soil profiles was also significantly shorter in field applied with reduced fertilizers than that with conventional one. It was shown that intercropping and fertilizer reduction would both cut apparent loss of nitrate down in varying degrees. [Conclusion] The research lays basis for high production of vegetables, reasonable fertilization and pollution reduction.
文摘Lateral root is primary organ for plant to explore and utilize soil nutrient efficiently. The development of lateral roots (LR) is controlled by both genetic factors and nutrient status in environment. To investigate the effects of nitrate (NO3-) on rice lateral root growth and nitrogen (N) uptake efficiency under upland condition, three treatments, including root-split culture and whole plant culture in N sufficient and deficient conditions, were used in a vermiculite culture experiment. Root-split treatment showed that the growth of lateral roots was stimulated by localized nitrate supply. However, in whole plant culture, elongation of lateral roots was induced by NO3- deficiency. The effects of NO3- on rice lateral root growth were genotype-dependent. Similar N concentration, soluble sugar concentration and N content in shoot were observed in both root-split treatment and whole plant culture under NO3- sufficient condition, suggesting that the nitrogen requirement for rice normal growth could be satisfied with only half of roots supplied with NO3-. In the root-split treatment, N uptake was positively correlated with the average of lateral root length (ALRL) in NO3--supplied side, suggesting that the ALRL is important for rice root N uptake in the environment where the nitrogen nutrient is limiting factor. No significant correlation was observed between N uptake and ALRL in whole plant culture under N sufficient condition, which implies that the length of lateral roots may not be the main factor to determine tire rice root N uptake in nutrient-rich zone. Morphological and metabolic evidence in this study provided some prospects for genetic improvement of root system characters to improve the efficiency of nutrient absorption in rice.
基金Supported by Special Fund for Agro-scientific Research in the Public Interest(201003014)Youth Foundation of Beijing Academy of Agricultural and Forestry Sciences(QNJJ201311)~~
文摘ObjectiveThe aim was to explore the movement of nitrate nitrogen in tall-fescue soils by different kinds of slow release nitrogen fertilizers. MethodBased on infiltration-tanks and test plots, a new and environment friendly fertilizer was explored. ResultThe results show that compared with urea treatment, slow-release nitrogen fertilizer treatments could reduce nitrate nitrogen content and leaching amount in soils. Compared with PCU30 and IU treatments, the PCU60 treatment became more efficient in reducing nitrate content and leaching amount in 0-90 cm soil layer. ConclusionIn summary, slow-release nitrogen fertilizer, which can reduce soil nitrate content and leaching losses, is a kind of novel fertilizer with high environmental benefit and promising application.
基金Supported by Agricultural Eco-environment Protection Program of Ministry of Agriculture(2110402-201258)~~
文摘The contents of nitrate nitrogen（NO-3-N） in underground water from typical planting areas in Liao river basin were analyzed, so as to provide theoretical basis for rational fertilization and effectively prevent the NO-3-N content from exceeding standard. The results showed that difference of the contents of NO-3-N in groundwater from different typical planting areas was significant. The highest content of NO-3-N in underground water was 37.4 mg/L from flower-growing region, then 22. 3 mg/L from maize-growing region, 21.9 mg/L from vegetable-growing region, and the lowest content of NO-3-N in underground water was 19.2 mg/L from rice-growing region. Except rice-growing region, the contents of NO-3-N in underground water of the samples in all planting areas were exceeding standard limit; potential health risk still existed in rice-growing region. Accordingly 12.5%-87.5%, 9.4%-75.5%, 17.9%-58.9% and 21.4%-96.0% of the samples were exceeding standard limit in maize growing region, rice-growing region, vegetable-growing region and flower-growing region. The contents of NO-3-N in under-groundwater before the rainy season was higher than that of NO-3-N in under-groundwater after the rainy season at the same depth of the well.
基金Supported by Scientific Research Fund of Agricultural Public-welfare Industry from Ministry of Agriculture"Study on Quantitative Evaluation and Controlling Technique of Carbon-nitrogen Budget in BohaiCostal Region"(200803036)National Scientific and Technological Supporting Project"Study and Demonstration on Key Technique of High-efficiency Fertilization with Single Cropping in one year in Northeastern Cold Region"(2008BADA4B06)~~
文摘The moving dynamics of nitrate nitrogen（NO3-N）in soil of maize field on meadow soil of Daling river valley in Liaoning and its rational fertilization controlling were discussed in this study by the designing of different kinds of N application methods.The results showed that the content of NO3-N in soil was increased with the amount of nitrogen fertilizer;At the same amount of nitrogen fertilizer,the content of NO3-N in soil showed a trend of chemical fertilizerstraw treatmentslow controlled release fertilizer.Based on the requirement of roots in different growth stages to nutrition,the migration directions of NO3-N could be regulated by each layer of soil.In the early growth stage,the NO3-N would move upward,while it moved downward in the late growth stage.Straw returning treatment could improve the keeping ability of soil to NO3-N and avoid the downward migration of NO3-N,as well as reduce the damage of groundwater pollution.The use of slow controlled release fertilizer had achieved the continuing releasing of nutrition.Moreover,the peak of nutrition releasing had been delayed for 30 d,which had met the requirement of nutrient supply in maturing stage.The yield of slow controlled release fertilizer treatment was the highest with the least accumulation of NO3-N and less negative influence on environment.The yield of straw returning treatment and chemical fertilizer treatment was closed to each other.
基金Project(2009ZX07315-005) supported by the National Water Pollution Controlled and Treatment Great Special of China
文摘The nitrate nitrogen removal efficiency of iron-carbon micro-electrolysis system was discussed in treating pharmaceutical wastewater with high nitrogen and refractory organic concentration. The results show that the granularity of fillings,pH,volume ratios of iron-carbon and gas-water,and HRT. have significant effects on the nitrogen removal efficiency of iron-carbon micro-electrolysis system. The iron-carbon micro-electrolysis system has a good removal efficiency of pharmaceutical wastewater with high nitrogen and refractory organic concentration when the influent TN,NH4+-N,NO3--N and BOD5/CODCr are 823 mg/L,30 mg/L,793 mg/L and 0.1,respectively,at the granularity of iron and carbon 0.425 mm,pH 3,iron-carbon ratio 3,gas-water ratio 5,HRT 1.5 h,and the removal rates of TN,NH4+-N and NO3--N achieve 51.5%,70% and 50.94%,respectively.
基金Supported by the Special Fund for Agro-scientific Research in the Public Interest(No.200903001-5)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)of China+1 种基金the Natural Science Foundation of Jiangsu Province,China(No.BK2010440)China Postdoctoral Science Foundation(No.20110491439)
文摘Ammonium(NH+4) is the main nitrogen(N) form for rice crops, while NH+4near the root surface can be oxidized to nitrate(NO-3)by NH+4-oxidizing bacteria. Nitrate can be accumulated within rice tissues and reused when N supply is insufficient. We compared the remobilization of NO-3stored in the tissue and vacuolar between two rice(Oryza sativa L.) cultivars, Yangdao 6(YD6, indica)with a high N use efficiency(NUE) and Wuyujing 3(WYJ3, japonica) with a low NUE and measured the uptake of NO-3, expression of nitrate reductase(NR), NO-3transporter genes(NRTs), and NR activity after 4 d of N starvation following 7-d cultivation in a solution containing 2.86 mmol L-1NO-3. The results showed that both tissue NO-3concentration and vacuolar NO-3activity were higher in YD6 than WYJ3 under N starvation. YD6 showed a 2- to 3-fold higher expression of OsNRT2.1 in roots on the 1st and 4th day of N starvation and had significantly higher values of NO-3uptake(maximum uptake velocity, Vmax) than the cultivar WYJ3.Furthermore, YD6 had significantly higher leaf and root maximum NR activity(NRAmax) and actual NR activity(NRAact) as well as stronger root expression of the two NR genes after the 1st day of N starvation. There were no significant differences in NRAmax and NRAact between the two rice cultivars on the 4th day of N starvation. The results suggested that YD6 had stronger NRA under N starvation, which might result in better NO-3re-utilization from the vacuole, and higher capacity for NO-3uptake and use, potentially explaining the higher NUE of YD6 compared with WYJ3.
基金Project supported by the National Natural Science Foundation of China(Nos.40471074 and 30390082).
文摘Rice is being increasingly cultivated in intermittently irrigated regions and also in aerobic soil in which Nitrate （NO3^- ） plays important role in nutrition of plant. However, there is no information regarding the influence of nitrate on the overall growth and uptake of nitrogen （N） in rice plant. Solution culture experiments were carried out to study the effects of NO^3- on the plant growth, uptake of N, and uptake kinetics of NH4^＋ in four typical rice （Oryza sativa L.） cultivars （conventional indica, conventional japonica, hybrid indica, and hybrid japonica）, and on plasma membrane potential in roots of two conventional rice cultivars （indica and japonica） at the seedling stage. The results obtained indicated that a ratio of 50/50 NH4^＋-N/NO3^--N increased the average biomass of rice shoots and roots by 20% when compared with that of 100/0 NH4^＋-N/NO3^--N. In case of the 50/50 ratio, as compared with the 100/0 ratio, total N accumulated in shoots and roots of rice increased on an average by 42% and 57%, respectively. Conventional indica responds to NO3^- more than any other cultivars that were tested. The NO^3- supply increased the maximum uptake rate （Vmax） of NH4^＋ by rice but did not show any effect on the apparent Michaelis-Menten constant （Km） value, with the average value of Vmax for NH4^＋ among the four cultivars being increased by 31.5% in comparison with those in the absence of NO3^-. This suggested that NO3^- significantly increased the numbers of the ammonium transporters. However, the lack of effect on the Km value also suggested that the presence of NO3^- had no effect on the affinity of the transporters for NH4^＋. The plasma membrane potential in the roots of conventional indica and japonica were greatly increased by the addition of NO3^- , suggesting that NO3^- could improve the uptake of N by roots of the rice plant. In conclusion, the mechanisms by which NO3^- enhances the growth and N uptake of rice plant was found by the increased value of Vmax of NH4^＋ and increased plasma membrane potential. Thus promotion of nitrification in paddy soil is of great significance for improving the production of rice.
基金Financial supports by the National Natural Science Foun-dation of China (30070431)the Key Technologies R&D Program of China during the 9th Five-Year Plan period(95-Agric-18-04)+1 种基金the Doctoral Fund of Ministry of Edu-cation of China (200805041061)the Earmarked Fund for Modern Agro-Industry Technology Research System, China
文摘The objective is to study whether the accumulation and utilization of plant N are controlled by Mo status in winter wheat cultivars. Mo-efficient cultivar 97003 （eft） and Mo-inefficient cultivar 97014 （ineff） were grown in severely Mo-deficient acidic soil （Tamm-reagent-extractable Mo 0.112 mg kg^-1） with （＋Mo） and without （-Mo） the application of 0.13 mg kg^-1 Mo. The accumulation and use efficiency of plant total N were significantly higher in ＋Mo than that in -Mo and in eft than that in ineff under Mo deficiency. N use efficiency was remarkably higher in maturity but it was forwarded to jointing stage after Mo supply, thus indicating that Mo supply promoted the N use efficiency besides N uptake and eff was efficient in N uptake and utilization. The overall activity of nitrate reductase （NR, EC 1.6.6.1） was significantly higher in ＋Mo than in -Mo and ratio of ＋Mo/-Mo was even to 14.8 at filleting stage for ineff. Activity of glutamine synthetase （GS, EC 6.3.1.2） was significantly lower in ＋Mo than in -Mo. Concentration of nitrate and glutamate were also significantly lower in ＋Mo than in -Mo, thus provided evidences for enhancing N use efficiency by Mo supply. Activities of NR and GS were significantly higher and concentrations of nitrate and glutamate were significantly lower in eff than ineff under Mo deficiency, thus indicated eff was more efficient in N reduction and utilization. It is therefore concluded that Mo could promote N accumulation and utilization in winter wheat which was directly related to NR and feedback regulated by GS. Higher Mo status also results in higher accumulation and utilization of plant N in eft.
