Reasonable nitrogen(N) application is a promising strategy for reducing crop cadmium(Cd) toxicity. However, the specific form of N and the required amount that affect Cd tolerance and accumulation in rice remain uncle...Reasonable nitrogen(N) application is a promising strategy for reducing crop cadmium(Cd) toxicity. However, the specific form of N and the required amount that affect Cd tolerance and accumulation in rice remain unclear. This study explored the influence of different N-fertilizer forms(NH_(4)NO_(3), NH_4Cl, and KNO_(3)) and dosages on Cd tolerance and uptake in Cd-stressed N-sensitive and N-insensitive indica rice accessions. The results indicated that the Cd tolerance of N-sensitive indica accessions is more robust than that of N-insensitive ones. Furthermore, the shoot Cd content and Cd translocation rate in both N-sensitive and N-insensitive indica accessions decreased with an appropriate supply of NH_(4)NO_(3) and NH_4Cl, whereas they were comparable or slightly increased with increased KNO_(3). Unfortunately, we did not find significant and regular differences in Cd accumulation or translocation between N-sensitive and N-insensitive rice accessions. Consistent with the reduction of shoot Cd content, the addition of NH_(4)NO_(3) and NH_4Cl also inhibited the instantaneous root Cd^(2+) uptake. The expression changes of Cd transport-related genes under different N forms and dosages suggested that the decreased shoot Cd content, caused by the increased supply of NH_(4)NO_(3) and NH_4Cl, is likely achieved by reducing the transcription of OsNRAMP1 and OsIRT1. In summary, our findings reveal that an appropriate supply of NH_(4)NO_(3) and NH_4Cl could reduce Cd uptake and transport in rice seedlings, suggesting that rational N management could reduce the Cd risk in rice production.展开更多
Over the past two decades,it has become increasingly apparent that early Mars may once have been warmer,wetter and more habitable for microbial life than it is today,which has spurred discussions about potential biosi...Over the past two decades,it has become increasingly apparent that early Mars may once have been warmer,wetter and more habitable for microbial life than it is today,which has spurred discussions about potential biosignatures that may be preserved in Martian sediments.An impediment to this line of research is the pervasive oxidation of Mars’surface due to photochemical oxidants that have likely destroyed remnants of organic matter.Here,we investigate whether nitrogen(N)transferred from biomass to phyllosilicate minerals during diagenesis can be preserved in oxidized mudrocks.We investigate two sequences of terrestrial Proterozoic red beds,namely the Sibley Group(1.4 Ga)in Canada and the Stoer Group(1.2 Ga)in Scotland,and we find enrichments in authigenic N in the range of several tens of ppm in both units.The highest concentrations(ca.100 ppm on average)are found in the most desiccated red beds of the Stoer Group,concurrent with enrichments in potassium(K).We discuss similarities and differences between the two sets of rocks with regards to salinity,pH,biological productivity and K-metasomatism,and we conclude that the ideal mechanism for the preservation of biogenic N in red beds may be in-situ release of ammonium from microbial mats into the clay substrate,possibly facilitated by early diagenetic,biologically induced illitization.Illite and smectite have been observed on Mars,and experiments suggest that Martian waters contained moderate amounts of dissolved K.Hence,it is conceivable that a similar K and N enrichment process could have occurred as to what we document for the Proterozoic,preserving evidence of life that may have survived to the modern day.展开更多
Plant growth and resilience to abiotic stresses,such as soil salinity and drought,depend intricately on nitrogen metabolism.This review explores nitrogen’s regulatory role in plant responses to these challenges,unvei...Plant growth and resilience to abiotic stresses,such as soil salinity and drought,depend intricately on nitrogen metabolism.This review explores nitrogen’s regulatory role in plant responses to these challenges,unveiling a dynamic interplay between nitrogen availability and abiotic stress.In the context of soil salinity,a nuanced rela-tionship emerges,featuring both antagonistic and synergistic interactions between salinity and nitrogen levels.Salinity-induced chlorophyll depletion in plants can be alleviated by optimal nitrogen supplementation;however,excessive nitrogen can exacerbate salinity stress.We delve into the complexities of this interaction and its agri-cultural implications.Nitrogen,a vital element within essential plant structures like chloroplasts,elicits diverse responses based on its availability.This review comprehensively examines manifestations of nitrogen deficiency and toxicity across various crop types,including cereals,vegetables,legumes,and fruits.Furthermore,we explore the broader consequences of nitrogen products,such as N_(2)O,NO_(2),and ammonia,on human health.Understand-ing the intricate relationship between nitrogen and salinity,especially chloride accumulation in nitrate-fed plants and sodium buildup in ammonium-fed plants,is pivotal for optimizing crop nitrogen management.However,prudent nitrogen use is essential,as overapplication can exacerbate nitrogen-related issues.Nitrogen Use Effi-ciency(NUE)is of paramount importance in addressing salinity challenges and enhancing sustainable crop productivity.Achieving this goal requires advancements in crop varieties with efficient nitrogen utilization,pre-cise timing and placement of nitrogen fertilizer application,and thoughtful nitrogen source selection to mitigate losses,particularly urea-based fertilizer volatilization.This review article delves into the multifaceted world of plant nitrogen metabolism and its pivotal role in enabling plant resilience to nutritional stress and abiotic challenges.It offers insights into future directions for sustainable agriculture.展开更多
High-purity magnesium ammonium phosphate （MAP） was precipitated by controlling pH value of the reaction system of 9.0-9.5. The thermal decomposition behavior of MAP and the adsorption properties of its pyrolysis pro...High-purity magnesium ammonium phosphate （MAP） was precipitated by controlling pH value of the reaction system of 9.0-9.5. The thermal decomposition behavior of MAP and the adsorption properties of its pyrolysis products toward ammonia-nitrogen were also studied by XRD, SEM, TGA-DTA and FT-IR methods. The results indicated that high-purity MAP was obtained at pH value of 9.0-9.5. Upon heating to 100-120℃ for 120 min, MAP was thermally decomposed, losing water and ammonia concomitantly with a reduction in grain size and crystallinity. The capacity of pyrolysis products for ammonia nitrogen adsorption reached 72.5 mg/g, with a removal rate of up to 95% from an 800 mg/L solution. The characteristic diffraction peaks corresponding to MAP mainly appeared in their XRD patterns after adsorption of ammonia nitrogen. The pyrolysis products of MAP at 100-120 ℃ could be recycling-used as the chemical treatment regents of ammonia nitrogen in the practical application.展开更多
[Objective] This research aimed to explore the existing forms of ammonium nitrogen adsorbed in a sandy soil with different particle sizes by extraction experiments and provide references for investigating the transpor...[Objective] This research aimed to explore the existing forms of ammonium nitrogen adsorbed in a sandy soil with different particle sizes by extraction experiments and provide references for investigating the transport and transformation of the ammonium in the vadose zone.[Method] Sandy soil sample was collected from a landfill and sieved into coarse sand and fine sand.The three kinds of samples were soaked in NH4Cl solution with different initial concentrations,respectively.Then,ammonium adsorbed in soil samples were extracted by three kinds of extraction agents with different extraction capacity,including water,KCl and CaCl2.[Result] The order of extraction capacity of different extraction agents was：water KCl CaCl2;when the concentration of ammonium was low in solution,the ammonium preferentially adsorbed in the exchangeable positions of minerals and mainly existed in the form of exchangeable ammonium;with the increase of concentration,ammonium entered inside the 2：1 clay minerals with enough driving force of the concentration differences and existed in the form of fixed ammonium;little fixed ammonium was observed in coarse sand samples,which was mainly existed in 2：1 clay minerals with strong extraction capacity.[Conclusion] The existing forms of ammonium were closely related to the mineral compositions in soil and the initial concentrations of ammonium.展开更多
RNAs isolated from ammonium- and nitrate-treated rice leaves were used to screen differentially expressed genes through mRNA differential display. A total of 72 bands appeared significant differences and some of them ...RNAs isolated from ammonium- and nitrate-treated rice leaves were used to screen differentially expressed genes through mRNA differential display. A total of 72 bands appeared significant differences and some of them were further confirmed by reverse Northern and Northern blot. The results showed that two genes, A-02 （Oryza sativa drought stress related mRNA） and A-03 （Zea mays partial mRNA for TFIIB-related protein） were highly up-regulated in the ammonium-fed rice leaves. The enzyme assays showed that the activities of the two anti-oxidative enzymes, catalase and peroxidase, and the content of a non-enzymic antioxidant, glutathione, were significantly higher in the ammonium-fed rice leaves than those in the nitrate-fed ones, indicating that the ammonium nutrition might be beneficial for rice plants to improve the stress resistance during growth and development.展开更多
Hippeastrum (Hippeastrum hybridum), a native of Central and South America, is a bulbous ornamental flowering plant in the Amaryllidaceae family. However, the correct balance of NH4 to NO3-nitrogen in a fertilizer mix ...Hippeastrum (Hippeastrum hybridum), a native of Central and South America, is a bulbous ornamental flowering plant in the Amaryllidaceae family. However, the correct balance of NH4 to NO3-nitrogen in a fertilizer mix for Hippeastrum plants is largely unknown. Nitrogen was applied 2x weekly following irrigation at either 0.6 g (high), 0.3 g (medium) or 0.15 g (low) total N every four months. Nitrogen was supplied in different combinations of NO3 and/or NH4. Nitrate:NH4-N ratios were either 100% NO3:0% NH4 (100NO3), 70% NO3:30% NH4 (70NO3), 50% NO3:50% NH4 (50NO3) (second group only), 30%NO3:70%NH4 (30NO3), or 0% NO3/100% NH4 (100NH4). Growth in bulb diameter after one year of fertilizer treatments not only increased from 0.15 to 0.6 g N (low to high level), but also differed with the form of N supplied to the plant. The largest diameter bulbs were produced in the 70NO3 and 50NO3 high N treatments. Within any NO3/NH4-N ratio grouping, fertilization at the high N rate resulted in larger diameter bulbs. No significant differences existed between treatments in the number of bulbs produced. Bulb growth was greater with a portion of N supplied as NO3 than with NH4-N alone. These results indicate that application of N as a mixture of NH4 and NO3 at 0.6 g per 4 months produces the largest increase in bulb diameter.展开更多
Can soil nitrate： ammonium ratios influence plant carbon： nitrogen ratios of the early succession plant？ Can plant carbon： nitrogen ratios limit the plant growth in early succession？ To address these two question...Can soil nitrate： ammonium ratios influence plant carbon： nitrogen ratios of the early succession plant？ Can plant carbon： nitrogen ratios limit the plant growth in early succession？ To address these two questions, we performed a two-factor （soil nitrate： ammonium ratio and plant density） randomized block design and a uniform-precision rotatable central composite design pot experiments to examine the relationships between soil nitrate： ammonium ratios, the carbon： nitrogen ratios and growth rate of Artemisia sphaerocephala seedlings. Under adequate nutrient status, both soil nitrate： ammonium ratios and plant density influenced the carbon： nitrogen ratios and growth rate of A. sphaerocephala seedlings. Under the lower soil nitrate： ammonium ratios, with the increase of soil nitrate： ammonium ratios, the growth rates of plant height and shoot biomass of A. sphaerocephala seedlings decreased significantly; with the increase of plant carbon： nitrogen ratios, the growth rates of shoot biomass of A. sphaerocephala seedlings decreased significantly. Soil nitrate： ammonium ratios affected the carbon： nitrogen ratios of A. sphaerocephala seedlings by plant nitrogen but not by plant carbon. Thus, soil nitrate： ammonium ratios influenced the carbon： nitrogen ratios of A. sphaerocephala seedlings, and hence influenced its growth rates. Our results suggest that under adequate nutrient environment, soil nitrate： ammonium ratios can be a limiting factor for the growth of the early succession plant.展开更多
The present article deals with the natural nitrogen-15 abundance of ammonium nitrogen and fixed ammonium in different soils. Variations in the natural 15N abundance of ammonium nitrogen mineralized in soils under anae...The present article deals with the natural nitrogen-15 abundance of ammonium nitrogen and fixed ammonium in different soils. Variations in the natural 15N abundance of ammonium nitrogen mineralized in soils under anaerobic incubation condition were related to soil pH. The δ 15N of mineralizable N in acid soils was lower but that in neutral and calcareous soils was higher compared with the δ 15N of total N in the soils. A variation tendency was also found in the δ 15N of amino-acid N in the hydrolysates of soils. The natural 15N abundance of fixed ammonium was higher than that of total N in most surface soils and other soil horizons, indicating that the increase of δ 15N in the soil horizons beneath subsurface horizon of some forest soils and acid paddy soils was related to the higher δ 15N value of fixed ammonium in the soil.展开更多
Nitrogen deficiency induces senescence and the expression of genes encoding ammonium transporters (AMTs) in terrestrial plants where the AMT family is subdivided into AMT1 and AMT2 subfamilies. Nitrogen starvation in ...Nitrogen deficiency induces senescence and the expression of genes encoding ammonium transporters (AMTs) in terrestrial plants where the AMT family is subdivided into AMT1 and AMT2 subfamilies. Nitrogen starvation in the red seaweed Pyropia yezoensis causes senescence-like discoloration. In this study, we identified five genes in P. yezoensis encoding AMT domain-containing proteins, which were phylogenetically categorized into the AMT1 subfamily. We also found a gene encoding a Rhesus protein (Rh) that was related to, but diverged from, AMTs. Moreover, our phylogenetic analysis showed that AMT domain-containing proteins from micro- and macro-algae belonged to either the AMT1 or Rh subfamily, indicating the absence of AMT2 in algae. Gene expression analyses revealed the presence of gametophyte- and sporophyte-specific AMT1 genes that were up-regulated transiently and continually, respectively, under nitrogen-deficient conditions. In addition, up-regulated sporophyte-specific gene expression was suppressed when nitrogen was resupplied. Accordingly, an expansion of the ancient AMT gene has produced AMT1 functional variants differing in temporal and nitrogen starvation-inducible expression patterns during the life cycle of P. yezoensis. These findings help elucidate the unique nutrition starvation responses involving functionally diverse AMT1 and Rh subfamilies in red seaweed.展开更多
In this study,nitrogen removal performance of the denitrifying ammonium oxidation(DAO)process was investigated when treating sulfamethoxazole(SMX)-laden secondary wastewater effluent.The influent SMX concentration sho...In this study,nitrogen removal performance of the denitrifying ammonium oxidation(DAO)process was investigated when treating sulfamethoxazole(SMX)-laden secondary wastewater effluent.The influent SMX concentration showed negligible effect on efficiencies for removal of nitrate and COD.However,the ammonium ions removal rate was moderately reduced,when the influent SMX concentration in wastewater reached 6 mg/L.Total nitrogen removal efficiency remained as high as 76.77%towards the day 158 at the end of experiment.Candidatus_Brocadia and Candidatus_Kuenenia were the functional anammox strains.The unclassified_f__Rhodobacteraceae sp.was predominant heterotrophic denitrifying strain in the studied reactor.The concentrations of soluble extracellular polymeric substances in sludge obviously increased from 16.76 mg/g VSS to 32.31 mg/g VSS,which might protect the nitrogen removal strains from high-concentration SMX.This result provides a theoretical and technical foundation for the application of denitrifying ammonium oxidation process in treating sulfamethoxazole-laden secondary wastewater effluent.展开更多
It is necessary to adjust reaction pH when a single kind of PO4^3- is used as phosphorus source to remove NH4^＋- N in a chemical precipitation process. However, this tedious step could be avoided in experiments that ...It is necessary to adjust reaction pH when a single kind of PO4^3- is used as phosphorus source to remove NH4^＋- N in a chemical precipitation process. However, this tedious step could be avoided in experiments that use the buffering effect of the composite phosphate and employ PO4^3- and HPO4^2- as phosphorus sources, pH was controlled by properly changing the proportion of PO4^3- to HPO4^2-. The influences of pH, material proportion and different addition modes of magnesium on NH4^＋-N removal efficiency were investigated, with NH4^3--N concentration in influent being 200 mg/L. It showed that the ratio of HPO4^2- ： PO4^3- was concerned with phosphorus and NH4^＋-N removal. Under the condition that the total amount of phosphate is definite, the removal efficiency of NH4^＋-N decreased with the enhancement of HPO4^2- concentration, while the efficiency of phosphorus increased. When increasing PO4^3- concentration, it benefited the removal of NH4^＋-N, but the remaining phosphorus was high. The results showed that NH4^＋-N concentration decreased from the initial 200 mg/L to 39.14 mg/L with the remaining PO4^3- at 5.14 mg/L if the ratio of HPO4^2- ： PO4^3- remained at 1：3.展开更多
High concentrations of ammonium nitrogen released from tannery sludge during storage in open air may cause nitrogen pollution to soil and groundwater.To study the transformation mechanism of NH_(4)^(+)-N by nitrifying...High concentrations of ammonium nitrogen released from tannery sludge during storage in open air may cause nitrogen pollution to soil and groundwater.To study the transformation mechanism of NH_(4)^(+)-N by nitrifying functional bacteria in tannery sludge contaminated soils,a series of contaminated soil culture experiments were conducted in this study.The contents of ammonium nitrogen(as NH_(4)^(+)-N),nitrite nitrogen(as NO_(2)^(−)-N)and nitrate nitrogen(as NO_(3)^(−)-N)were analyzed during the culture period under different conditions of pollution load,soil particle and redox environment.Sigmodial equation was used to interpret the change of NO_(3)^(−)-N with time in contaminated soils.The abundance variations of nitrifying functional genes(amoA and nxrA)were also detected using the real-time quantitative fluorescence PCR method.The results show that the nitrification of NH_(4)^(+)-N was aggravated in the contaminated silt soil and fine sand under the condition of lower pollution load,finer particle size and more oxidizing environment.The sigmodial equation well fitted the dynamic accumulation curve of the NO_(3)^(−)-N content in the tannery sludge contaminated soils.The Cr(III)content increased with increasing pollution load,which inhibited the reproduction and activity of nitrifying bacteria in the soils,especially in coarse-grained soil.The accumulation of NO_(2)^(−)-N contents became more obvious with the increase of pollution load in the fine sand,and only 41.5%of the NH_(4)^(+)-N was transformed to NO_(3)^(−)-N.The redox environment was the main factor affecting nitrification process in the soil.Compared to the aerobic soil environment,the transformation of NH_(4)^(+)-N was significantly inhibited under anaerobic incubation condition,and the NO_(3)^(−)-N contents decreased by 37.2%,61.9%and 91.9%under low,medium and high pollution loads,respectively.Nitrification was stronger in the silt soil since its copy number of amoA and nxrA genes was two times larger than that of fine sand.Moreover,the copy numbers of amoA and nxrA genes in the silt soil under the aerobic environment were 2.7 times and 2.2 times larger than those in the anaerobic environment.The abundance changes of the amoA and nxrA functional genes have a positive correlation with the nitrification intensity in the tannery sludge-contaminated soil.展开更多
Based on the dynamic method,a quaternary system of ammonium polyphosphate (APP)-urea ammonium nitrate (UAN,CO(NH_(2))_(2)-NH_(4)NO_(3))-potassium chloride (KCl)-H_(2)O and its subsystems (APP-[CO(NH_(2))_(2)-NH_(4)NO_...Based on the dynamic method,a quaternary system of ammonium polyphosphate (APP)-urea ammonium nitrate (UAN,CO(NH_(2))_(2)-NH_(4)NO_(3))-potassium chloride (KCl)-H_(2)O and its subsystems (APP-[CO(NH_(2))_(2)-NH_(4)NO_(3)]-H_(2)O,KCl-[CO(NH_(2))_(2)-NH_(4)NO_(3)]-H_(2)O and APP-KCl-H_(2)O) were systematically investigated at the temperature of 273.2 K.Each ternary phase diagram contains one invariant point and three crystallization regions.The crystallization regions are:(1)(NH_(4))_(3)HP_(2)O_(7),(NH_(4))_(4)P_(2)O_(7)and ((NH_(4))_(3)HP_(2)O_(7)+(NH_(4))_(4)P_(2)O_(7)) for APP-[CO(NH_(2))_(2)-NH_(4)NO_(3)]-H_(2)O diagram;(2) KCl,KNO_(3)and(KCl+KNO_(3)) for KCl-[CO(NH_(2))_(2)-NH_(4)NO_(3)]-H_(2)O diagram and (3)(NH_(4))_(3)HP_(2)O_(7),KCl and((NH_(4))_(3)HP_(2)O_(7)+KCl) for APP-KCl-H_(2)O diagram.The quaternary phase diagram of APP-[CO(NH_(2))_(2)-NH_(4)NO_(3)]-KCl-H_(2)O has no quaternary invariant point but includes four solid phase crystallization regions,i.e.,(NH_(4))_(3)HP_(2)O_(7),(NH_(4))_(4)P_(2)O_(7),KNO_(3)and KCl,in which the KNO_(3)region occupies the largest area.The maximum total nutrient content (N+P_(2)O_(5)+K_(2)O) existing as ionic forms in the APP-[CO(NH_(2))_(2)-NH_(4)NO_(3)]-H_(2)O,KCl-[CO(NH_(2))_(2)-NH_(4)NO_(3)]-H_(2)O,APP-KCl-H_(2)O and quaternary systems is 44.70%,32.86%,45.56%and 46.23%(mass),respectively,indicating that the maximum nutrient content can be reached using raw materials of the corresponding systems to prepare liquid fertilizer.In the quaternary system,the content of NH_(4)~+-N ascends with the increase of the total nutrient content,while the contents of NO_(3)^(-)-N and CO(NH_(2))_(2)-N increase with elevated total N.This work can help optimize the operating parameters for the production,storage and transportation of liquid fertilizers.展开更多
基金supported by the National Natural Science Foundation of China (Grant No.31971872)the Open Research Fund of State Key Laboratory of Hybrid Rice, China (Grant No.2022KF02)+3 种基金the National Natural Science Foundation of China (Grant Nos.32101755 and 32188102)the Zhejiang Provincial Natural Science Foundation, China (Grant No.LY22C130005)the Key Research and Development Program of Zhejiang Province, China (Grant No.2021C02056)the ‘Pioneer’ and ‘Leading Goose’ R&D Program of Zhejiang, China (Grant No.2023C02014)。
文摘Reasonable nitrogen(N) application is a promising strategy for reducing crop cadmium(Cd) toxicity. However, the specific form of N and the required amount that affect Cd tolerance and accumulation in rice remain unclear. This study explored the influence of different N-fertilizer forms(NH_(4)NO_(3), NH_4Cl, and KNO_(3)) and dosages on Cd tolerance and uptake in Cd-stressed N-sensitive and N-insensitive indica rice accessions. The results indicated that the Cd tolerance of N-sensitive indica accessions is more robust than that of N-insensitive ones. Furthermore, the shoot Cd content and Cd translocation rate in both N-sensitive and N-insensitive indica accessions decreased with an appropriate supply of NH_(4)NO_(3) and NH_4Cl, whereas they were comparable or slightly increased with increased KNO_(3). Unfortunately, we did not find significant and regular differences in Cd accumulation or translocation between N-sensitive and N-insensitive rice accessions. Consistent with the reduction of shoot Cd content, the addition of NH_(4)NO_(3) and NH_4Cl also inhibited the instantaneous root Cd^(2+) uptake. The expression changes of Cd transport-related genes under different N forms and dosages suggested that the decreased shoot Cd content, caused by the increased supply of NH_(4)NO_(3) and NH_4Cl, is likely achieved by reducing the transcription of OsNRAMP1 and OsIRT1. In summary, our findings reveal that an appropriate supply of NH_(4)NO_(3) and NH_4Cl could reduce Cd uptake and transport in rice seedlings, suggesting that rational N management could reduce the Cd risk in rice production.
基金EES acknowledges funding from a NERC Frontiers grant(NE/V010824/1)Leverhulme Trust research grant(RPG-2022-313).
文摘Over the past two decades,it has become increasingly apparent that early Mars may once have been warmer,wetter and more habitable for microbial life than it is today,which has spurred discussions about potential biosignatures that may be preserved in Martian sediments.An impediment to this line of research is the pervasive oxidation of Mars’surface due to photochemical oxidants that have likely destroyed remnants of organic matter.Here,we investigate whether nitrogen(N)transferred from biomass to phyllosilicate minerals during diagenesis can be preserved in oxidized mudrocks.We investigate two sequences of terrestrial Proterozoic red beds,namely the Sibley Group(1.4 Ga)in Canada and the Stoer Group(1.2 Ga)in Scotland,and we find enrichments in authigenic N in the range of several tens of ppm in both units.The highest concentrations(ca.100 ppm on average)are found in the most desiccated red beds of the Stoer Group,concurrent with enrichments in potassium(K).We discuss similarities and differences between the two sets of rocks with regards to salinity,pH,biological productivity and K-metasomatism,and we conclude that the ideal mechanism for the preservation of biogenic N in red beds may be in-situ release of ammonium from microbial mats into the clay substrate,possibly facilitated by early diagenetic,biologically induced illitization.Illite and smectite have been observed on Mars,and experiments suggest that Martian waters contained moderate amounts of dissolved K.Hence,it is conceivable that a similar K and N enrichment process could have occurred as to what we document for the Proterozoic,preserving evidence of life that may have survived to the modern day.
基金The authors extend their appreciation to the Deanship of Scientific Research at King Khalid University for funding this work through large group research project under Grant Number RGP2/304/44.
文摘Plant growth and resilience to abiotic stresses,such as soil salinity and drought,depend intricately on nitrogen metabolism.This review explores nitrogen’s regulatory role in plant responses to these challenges,unveiling a dynamic interplay between nitrogen availability and abiotic stress.In the context of soil salinity,a nuanced rela-tionship emerges,featuring both antagonistic and synergistic interactions between salinity and nitrogen levels.Salinity-induced chlorophyll depletion in plants can be alleviated by optimal nitrogen supplementation;however,excessive nitrogen can exacerbate salinity stress.We delve into the complexities of this interaction and its agri-cultural implications.Nitrogen,a vital element within essential plant structures like chloroplasts,elicits diverse responses based on its availability.This review comprehensively examines manifestations of nitrogen deficiency and toxicity across various crop types,including cereals,vegetables,legumes,and fruits.Furthermore,we explore the broader consequences of nitrogen products,such as N_(2)O,NO_(2),and ammonia,on human health.Understand-ing the intricate relationship between nitrogen and salinity,especially chloride accumulation in nitrate-fed plants and sodium buildup in ammonium-fed plants,is pivotal for optimizing crop nitrogen management.However,prudent nitrogen use is essential,as overapplication can exacerbate nitrogen-related issues.Nitrogen Use Effi-ciency(NUE)is of paramount importance in addressing salinity challenges and enhancing sustainable crop productivity.Achieving this goal requires advancements in crop varieties with efficient nitrogen utilization,pre-cise timing and placement of nitrogen fertilizer application,and thoughtful nitrogen source selection to mitigate losses,particularly urea-based fertilizer volatilization.This review article delves into the multifaceted world of plant nitrogen metabolism and its pivotal role in enabling plant resilience to nutritional stress and abiotic challenges.It offers insights into future directions for sustainable agriculture.
基金Project(ZDSY20120619093952884)supported by Shenzhen Strategic New Industry Development,China
文摘High-purity magnesium ammonium phosphate （MAP） was precipitated by controlling pH value of the reaction system of 9.0-9.5. The thermal decomposition behavior of MAP and the adsorption properties of its pyrolysis products toward ammonia-nitrogen were also studied by XRD, SEM, TGA-DTA and FT-IR methods. The results indicated that high-purity MAP was obtained at pH value of 9.0-9.5. Upon heating to 100-120℃ for 120 min, MAP was thermally decomposed, losing water and ammonia concomitantly with a reduction in grain size and crystallinity. The capacity of pyrolysis products for ammonia nitrogen adsorption reached 72.5 mg/g, with a removal rate of up to 95% from an 800 mg/L solution. The characteristic diffraction peaks corresponding to MAP mainly appeared in their XRD patterns after adsorption of ammonia nitrogen. The pyrolysis products of MAP at 100-120 ℃ could be recycling-used as the chemical treatment regents of ammonia nitrogen in the practical application.
基金Supported by Major Project of Water Pollution Control and Treatment(2009ZX07424-002)~~
文摘[Objective] This research aimed to explore the existing forms of ammonium nitrogen adsorbed in a sandy soil with different particle sizes by extraction experiments and provide references for investigating the transport and transformation of the ammonium in the vadose zone.[Method] Sandy soil sample was collected from a landfill and sieved into coarse sand and fine sand.The three kinds of samples were soaked in NH4Cl solution with different initial concentrations,respectively.Then,ammonium adsorbed in soil samples were extracted by three kinds of extraction agents with different extraction capacity,including water,KCl and CaCl2.[Result] The order of extraction capacity of different extraction agents was：water KCl CaCl2;when the concentration of ammonium was low in solution,the ammonium preferentially adsorbed in the exchangeable positions of minerals and mainly existed in the form of exchangeable ammonium;with the increase of concentration,ammonium entered inside the 2：1 clay minerals with enough driving force of the concentration differences and existed in the form of fixed ammonium;little fixed ammonium was observed in coarse sand samples,which was mainly existed in 2：1 clay minerals with strong extraction capacity.[Conclusion] The existing forms of ammonium were closely related to the mineral compositions in soil and the initial concentrations of ammonium.
文摘RNAs isolated from ammonium- and nitrate-treated rice leaves were used to screen differentially expressed genes through mRNA differential display. A total of 72 bands appeared significant differences and some of them were further confirmed by reverse Northern and Northern blot. The results showed that two genes, A-02 （Oryza sativa drought stress related mRNA） and A-03 （Zea mays partial mRNA for TFIIB-related protein） were highly up-regulated in the ammonium-fed rice leaves. The enzyme assays showed that the activities of the two anti-oxidative enzymes, catalase and peroxidase, and the content of a non-enzymic antioxidant, glutathione, were significantly higher in the ammonium-fed rice leaves than those in the nitrate-fed ones, indicating that the ammonium nutrition might be beneficial for rice plants to improve the stress resistance during growth and development.
文摘Hippeastrum (Hippeastrum hybridum), a native of Central and South America, is a bulbous ornamental flowering plant in the Amaryllidaceae family. However, the correct balance of NH4 to NO3-nitrogen in a fertilizer mix for Hippeastrum plants is largely unknown. Nitrogen was applied 2x weekly following irrigation at either 0.6 g (high), 0.3 g (medium) or 0.15 g (low) total N every four months. Nitrogen was supplied in different combinations of NO3 and/or NH4. Nitrate:NH4-N ratios were either 100% NO3:0% NH4 (100NO3), 70% NO3:30% NH4 (70NO3), 50% NO3:50% NH4 (50NO3) (second group only), 30%NO3:70%NH4 (30NO3), or 0% NO3/100% NH4 (100NH4). Growth in bulb diameter after one year of fertilizer treatments not only increased from 0.15 to 0.6 g N (low to high level), but also differed with the form of N supplied to the plant. The largest diameter bulbs were produced in the 70NO3 and 50NO3 high N treatments. Within any NO3/NH4-N ratio grouping, fertilization at the high N rate resulted in larger diameter bulbs. No significant differences existed between treatments in the number of bulbs produced. Bulb growth was greater with a portion of N supplied as NO3 than with NH4-N alone. These results indicate that application of N as a mixture of NH4 and NO3 at 0.6 g per 4 months produces the largest increase in bulb diameter.
基金supported in part by the National Basic Research Program of China (2009CB421303)supported by National Natural Science Foundation of China (30970546)
文摘Can soil nitrate： ammonium ratios influence plant carbon： nitrogen ratios of the early succession plant？ Can plant carbon： nitrogen ratios limit the plant growth in early succession？ To address these two questions, we performed a two-factor （soil nitrate： ammonium ratio and plant density） randomized block design and a uniform-precision rotatable central composite design pot experiments to examine the relationships between soil nitrate： ammonium ratios, the carbon： nitrogen ratios and growth rate of Artemisia sphaerocephala seedlings. Under adequate nutrient status, both soil nitrate： ammonium ratios and plant density influenced the carbon： nitrogen ratios and growth rate of A. sphaerocephala seedlings. Under the lower soil nitrate： ammonium ratios, with the increase of soil nitrate： ammonium ratios, the growth rates of plant height and shoot biomass of A. sphaerocephala seedlings decreased significantly; with the increase of plant carbon： nitrogen ratios, the growth rates of shoot biomass of A. sphaerocephala seedlings decreased significantly. Soil nitrate： ammonium ratios affected the carbon： nitrogen ratios of A. sphaerocephala seedlings by plant nitrogen but not by plant carbon. Thus, soil nitrate： ammonium ratios influenced the carbon： nitrogen ratios of A. sphaerocephala seedlings, and hence influenced its growth rates. Our results suggest that under adequate nutrient environment, soil nitrate： ammonium ratios can be a limiting factor for the growth of the early succession plant.
基金Project supported by the National Natural Science Foundation of China.
文摘The present article deals with the natural nitrogen-15 abundance of ammonium nitrogen and fixed ammonium in different soils. Variations in the natural 15N abundance of ammonium nitrogen mineralized in soils under anaerobic incubation condition were related to soil pH. The δ 15N of mineralizable N in acid soils was lower but that in neutral and calcareous soils was higher compared with the δ 15N of total N in the soils. A variation tendency was also found in the δ 15N of amino-acid N in the hydrolysates of soils. The natural 15N abundance of fixed ammonium was higher than that of total N in most surface soils and other soil horizons, indicating that the increase of δ 15N in the soil horizons beneath subsurface horizon of some forest soils and acid paddy soils was related to the higher δ 15N value of fixed ammonium in the soil.
文摘Nitrogen deficiency induces senescence and the expression of genes encoding ammonium transporters (AMTs) in terrestrial plants where the AMT family is subdivided into AMT1 and AMT2 subfamilies. Nitrogen starvation in the red seaweed Pyropia yezoensis causes senescence-like discoloration. In this study, we identified five genes in P. yezoensis encoding AMT domain-containing proteins, which were phylogenetically categorized into the AMT1 subfamily. We also found a gene encoding a Rhesus protein (Rh) that was related to, but diverged from, AMTs. Moreover, our phylogenetic analysis showed that AMT domain-containing proteins from micro- and macro-algae belonged to either the AMT1 or Rh subfamily, indicating the absence of AMT2 in algae. Gene expression analyses revealed the presence of gametophyte- and sporophyte-specific AMT1 genes that were up-regulated transiently and continually, respectively, under nitrogen-deficient conditions. In addition, up-regulated sporophyte-specific gene expression was suppressed when nitrogen was resupplied. Accordingly, an expansion of the ancient AMT gene has produced AMT1 functional variants differing in temporal and nitrogen starvation-inducible expression patterns during the life cycle of P. yezoensis. These findings help elucidate the unique nutrition starvation responses involving functionally diverse AMT1 and Rh subfamilies in red seaweed.
基金This research was supported by the Natural Science Foundation of Shandong Province(ZR2019MEE038)the Fundamental Research Funds for the Central Universities(19CX02038A).
文摘In this study,nitrogen removal performance of the denitrifying ammonium oxidation(DAO)process was investigated when treating sulfamethoxazole(SMX)-laden secondary wastewater effluent.The influent SMX concentration showed negligible effect on efficiencies for removal of nitrate and COD.However,the ammonium ions removal rate was moderately reduced,when the influent SMX concentration in wastewater reached 6 mg/L.Total nitrogen removal efficiency remained as high as 76.77%towards the day 158 at the end of experiment.Candidatus_Brocadia and Candidatus_Kuenenia were the functional anammox strains.The unclassified_f__Rhodobacteraceae sp.was predominant heterotrophic denitrifying strain in the studied reactor.The concentrations of soluble extracellular polymeric substances in sludge obviously increased from 16.76 mg/g VSS to 32.31 mg/g VSS,which might protect the nitrogen removal strains from high-concentration SMX.This result provides a theoretical and technical foundation for the application of denitrifying ammonium oxidation process in treating sulfamethoxazole-laden secondary wastewater effluent.
文摘It is necessary to adjust reaction pH when a single kind of PO4^3- is used as phosphorus source to remove NH4^＋- N in a chemical precipitation process. However, this tedious step could be avoided in experiments that use the buffering effect of the composite phosphate and employ PO4^3- and HPO4^2- as phosphorus sources, pH was controlled by properly changing the proportion of PO4^3- to HPO4^2-. The influences of pH, material proportion and different addition modes of magnesium on NH4^＋-N removal efficiency were investigated, with NH4^3--N concentration in influent being 200 mg/L. It showed that the ratio of HPO4^2- ： PO4^3- was concerned with phosphorus and NH4^＋-N removal. Under the condition that the total amount of phosphate is definite, the removal efficiency of NH4^＋-N decreased with the enhancement of HPO4^2- concentration, while the efficiency of phosphorus increased. When increasing PO4^3- concentration, it benefited the removal of NH4^＋-N, but the remaining phosphorus was high. The results showed that NH4^＋-N concentration decreased from the initial 200 mg/L to 39.14 mg/L with the remaining PO4^3- at 5.14 mg/L if the ratio of HPO4^2- ： PO4^3- remained at 1：3.
基金supported jointly by Natural Science Foundation of Hebei Province(D2020504003)National Key Research and Development Program of China(No.2019YFC1805300).
文摘High concentrations of ammonium nitrogen released from tannery sludge during storage in open air may cause nitrogen pollution to soil and groundwater.To study the transformation mechanism of NH_(4)^(+)-N by nitrifying functional bacteria in tannery sludge contaminated soils,a series of contaminated soil culture experiments were conducted in this study.The contents of ammonium nitrogen(as NH_(4)^(+)-N),nitrite nitrogen(as NO_(2)^(−)-N)and nitrate nitrogen(as NO_(3)^(−)-N)were analyzed during the culture period under different conditions of pollution load,soil particle and redox environment.Sigmodial equation was used to interpret the change of NO_(3)^(−)-N with time in contaminated soils.The abundance variations of nitrifying functional genes(amoA and nxrA)were also detected using the real-time quantitative fluorescence PCR method.The results show that the nitrification of NH_(4)^(+)-N was aggravated in the contaminated silt soil and fine sand under the condition of lower pollution load,finer particle size and more oxidizing environment.The sigmodial equation well fitted the dynamic accumulation curve of the NO_(3)^(−)-N content in the tannery sludge contaminated soils.The Cr(III)content increased with increasing pollution load,which inhibited the reproduction and activity of nitrifying bacteria in the soils,especially in coarse-grained soil.The accumulation of NO_(2)^(−)-N contents became more obvious with the increase of pollution load in the fine sand,and only 41.5%of the NH_(4)^(+)-N was transformed to NO_(3)^(−)-N.The redox environment was the main factor affecting nitrification process in the soil.Compared to the aerobic soil environment,the transformation of NH_(4)^(+)-N was significantly inhibited under anaerobic incubation condition,and the NO_(3)^(−)-N contents decreased by 37.2%,61.9%and 91.9%under low,medium and high pollution loads,respectively.Nitrification was stronger in the silt soil since its copy number of amoA and nxrA genes was two times larger than that of fine sand.Moreover,the copy numbers of amoA and nxrA genes in the silt soil under the aerobic environment were 2.7 times and 2.2 times larger than those in the anaerobic environment.The abundance changes of the amoA and nxrA functional genes have a positive correlation with the nitrification intensity in the tannery sludge-contaminated soil.
基金fund supported by the National Natural Science Foundation of China (32172677)。
文摘Based on the dynamic method,a quaternary system of ammonium polyphosphate (APP)-urea ammonium nitrate (UAN,CO(NH_(2))_(2)-NH_(4)NO_(3))-potassium chloride (KCl)-H_(2)O and its subsystems (APP-[CO(NH_(2))_(2)-NH_(4)NO_(3)]-H_(2)O,KCl-[CO(NH_(2))_(2)-NH_(4)NO_(3)]-H_(2)O and APP-KCl-H_(2)O) were systematically investigated at the temperature of 273.2 K.Each ternary phase diagram contains one invariant point and three crystallization regions.The crystallization regions are:(1)(NH_(4))_(3)HP_(2)O_(7),(NH_(4))_(4)P_(2)O_(7)and ((NH_(4))_(3)HP_(2)O_(7)+(NH_(4))_(4)P_(2)O_(7)) for APP-[CO(NH_(2))_(2)-NH_(4)NO_(3)]-H_(2)O diagram;(2) KCl,KNO_(3)and(KCl+KNO_(3)) for KCl-[CO(NH_(2))_(2)-NH_(4)NO_(3)]-H_(2)O diagram and (3)(NH_(4))_(3)HP_(2)O_(7),KCl and((NH_(4))_(3)HP_(2)O_(7)+KCl) for APP-KCl-H_(2)O diagram.The quaternary phase diagram of APP-[CO(NH_(2))_(2)-NH_(4)NO_(3)]-KCl-H_(2)O has no quaternary invariant point but includes four solid phase crystallization regions,i.e.,(NH_(4))_(3)HP_(2)O_(7),(NH_(4))_(4)P_(2)O_(7),KNO_(3)and KCl,in which the KNO_(3)region occupies the largest area.The maximum total nutrient content (N+P_(2)O_(5)+K_(2)O) existing as ionic forms in the APP-[CO(NH_(2))_(2)-NH_(4)NO_(3)]-H_(2)O,KCl-[CO(NH_(2))_(2)-NH_(4)NO_(3)]-H_(2)O,APP-KCl-H_(2)O and quaternary systems is 44.70%,32.86%,45.56%and 46.23%(mass),respectively,indicating that the maximum nutrient content can be reached using raw materials of the corresponding systems to prepare liquid fertilizer.In the quaternary system,the content of NH_(4)~+-N ascends with the increase of the total nutrient content,while the contents of NO_(3)^(-)-N and CO(NH_(2))_(2)-N increase with elevated total N.This work can help optimize the operating parameters for the production,storage and transportation of liquid fertilizers.
