Destratification and oxygenation efficiency of a water-lifting aerator system in a deep reservoir:Implications for optimal operation

Thermal stratification is a common phenomenon in lakes and reservoirs and has a significant influence on water quality dynamics. Heihe Reservoir is a canyon-shaped reservoir in Shaanxi Province with strong thermal stratification. Therefore, eight water-lifting aerators （WLAs） were installed in this reservoir, which could overcome thermal stratification and increase oxygenation with gas flows between 20 and 50 m3/hr, and oxygenate the hypolimnion with gas flows less than 20 m3/hr. To examine the destratification efficiency of the WLA system, we used a three- dimensional hydrodynamic module based on MIKE 3 to simulate the thermal structure of Heihe Reservoir and compared the simulations with measured data. Results showed that operation of the WLA system promoted water mixing and effectively oxygenated the hypolimnion. Through the established energy utilization assessment method, the energy utilization efficiency of the WLA system was between 5.36% and 7.30%, indicating the capability of the technique for destratification in such a large reservoir. When the surface water temperature dropped to the theoretical mixed water temperature calculated by the energy utilization assessment method, reducing gas flow could save energy. This would prevent anaerobic conditions from occurring in the bottom water and maintain good water quality in Heihe Reservoir.

A new method of inhibiting pollutant release from source water reservoir sediment by adding chemical stabilization agents combined with water-lifting aerator

Source water reservoirs easily become thermally and dynamically stratified. Internal pollution released from reservoir sediments is the main cause of water quality problems. To mitigate the internal pollution more effectively, a new method, which combined chemical stabilization with water lifting aerator （WLA） technology, was proposed and its effciency in inhibiting pollutant release was studied by controlled sediment-water interface experiments. The results showed that this new method can inhibit pollutant release from sediment effectively. The values of mean effciency （E） in different reactors 2#–5# （1# with no agent, 2# 10 mg/L polymeric aluminum chloride （PAC） was added, 3# 20 mg/L PAC was added, 4# 30 mg/L PAC was added, 5# 20 mg/L PAC and 0.2 mg/L palyacrylamide （PAM） were added） for PO43- were 35.0%, 43.9%, 50.4% and 63.6%, respectively. This showed that the higher the PAC concentration was, the better the inhibiting effciency was, and PAM addition strengthened the inhibiting effciency significantly. For Fe2＋, the corresponding values of E for the reactors 2#–5# were 22.9%, 47.2%, 34.3% and 46.2%, respectively. The inhibiting effect of PAC and PAM on Mn release remained positive for a relatively short time, about 10 days, and was not so effective as for PO43- and Fe2＋. The average effciencies in inhibiting the release of UV254 were 35.3%, 25.9%, 35.5%, 38.9% and 39.5% for reactors 2#–5#, respectively. The inhibiting mechanisms of the agents for different pollutants varied among the conditions and should be studied further.

Aerated irrigation increases tomato production by improving soil nitrogen availability

Soil nitrogen(N)is the main limiting nutrient for plant growth,which is sensitive to variations in the soil oxygen environment.To provide insights into plant N accumulation and yield under aerated and drip irrigation,a greenhouse tomato experiment was conducted with six treatments,including three fertilization types:inorganic fertilizer(NPK);organic fertilizer(OM);chemical(75%of applied N)+organic fertilizer(25%)(NPK+OM)under drip irrigation(DI)and aerated irrigation(AI)methods.Under Al,total soil carbon mineralization(C_(min))was significantly higher(by 5.7-7.0%)than under DI irrigation.C_(min)in the fertilizer treatments followed the order NPK+OM>OM>NPK under both AI and DI.Potentially mineralizable C(C_(0))and N(N_(0))was greater under AI than under DI.Gross N mineralization,gross nitrification,and NH_(4)^(+)immobilization rates were significantly higher under the AINPK treatment than the DINPK treatment by 2.58-3.27-,1.25-1.44-,and 1-1.26-fold,respectively.These findings demonstrated that AI and the addition of organic fertilizer accelerated the turnover of soil organic matter and N transformation processes,thereby enhancing N availability.Moreover,the combination of AI and organic fertilizer application was found to promote root growth(8.4-10.6%),increase the duration of the period of rapid N accumulation(ΔT),and increase the maximum N accumulation rate(V_(max)),subsequently encouraging aboveground dry matter accumulation.Consequently,the AI treatment yield was significantly greater(by 6.3-12.4%)than under the DI treatment.Further,N partial factor productivity(NPFP)and N harvest index(NHI)were greater under AI than under DI,by 6.3 to 12.4%,and 4.6 to 8.1%,respectively.The rankings of yield and NPFP remained consistent,with NPK+OM>OM>NPK under both AI and DI treatments.These results highlighted the positive impacts of AI and organic fertilizer application on soil N availability,N uptake,and overall crop yield in tomato.The optimal management measure was identified as the AINPK+OM treatment,which led to more efficient N management,better crop growth,higher yield,and more sustainable agricultural practices.

Energy Dissipation with Geometric Parameters in Unbaffled Surface Aerator

The dissipation rate of turbulent kinetic energy （ ε ） is the key process parameters for mixing in surface aerators. At constant dynamic variables （rotational speed）, ε is greatly affected by the geometric parameters, such as impeller diameter, cross-sectional area of the tank, liquid height, rotor blade length and immersion height. By doing numerical computation by visimix, present work analyzes the effect of non-dimensional （which is non-dimensionalized through rotor diameter） geometric parameters on ε. With an increase in liquid height, there is an increase in the case of energy dissipation. In the case of tank area and blade length, it is vice versa. Energy dissipation is not affected by the variation in immersion height of the impeller.

Air-vent layouts and water-air flow behaviors of a wide spillway aerator

A spillway aerator should guarantee favorable flow conditions in the coupled water-air system even if the aerator is unconventionally wide. Eight air-vent configurations are devised and incorporated into a 35-m wide chute aerator for a generalized study. Computational fluid dynamics(CFD) simulations are performed to explore their effects on water-jet and air-cavity features. The Re-normalisation group(RNG) k-ε turbulence model and the two-fluid model are combined to predict the two-phase flow field. The results demonstrate appreciable influences of the vent layouts on the water-air flow. The air vents stir the air motion and re-distribute the cavity air pressure. Once the vent layout is modified, reciprocal adjustments exist between the jet behavior and air-pressure field in the cavity, thus leading to considerable differences in air-flow rate, jet-trajectory length, vent air-flow distribution across the chute, etc. The large width plays a discernable role in affecting the aerated flow. Telling differences exist between the near-wall region and the central part of the chute. To improve the duct pressure propagation, a gradual augment of the vent area should be assigned towards the chute center. Relative to single-slot vents across the flow, the layouts with segregated vents gain by comparison. A designer should see to it that a vented aerator operates satisfactorily for a given range of flow discharges.

Modeling the Mangla Dam Spillway for Cavitation and Aerators Optimization

This study evaluated the effects of increased reservoir conservation level by 40 ft (12.2 m), on spillway velocities;it’s discharging capacity and associated cavitation risk. The study optimized the aerators size and shape to avoid cavitations. The mathematical model was used to estimate the flow velocities and cavitation risk, when scale model study assessed the spillway discharging capacity and optimized the performance of the aerators for modified conditions. The mathematical model simulations showed increased flow velocities and damage index for modified conditions. The damage potential was 2 - 3 times higher with modifications and falls within the major to catastrophic region. The scale model study showed that discharging capacity of the spillway can effectively be restricted to original design by raising spillway crest by 5.0 ft (1.52 m). The scale model study also showed that the two aerators near sluice and at the chute with an air duct pipe of 3.0 ft diameter can improve the free surface flow profile reducing the risks of cavitation. Simulations for several configurations demonstrated clearer affect of aerators ramps on flow trajectory and gate opening. It also depicted that the height of the ramp of sluice aerator has a positive effect on the flow performance to about 7.5 inches (19 cm), when further increase in the ramp height reduced the flow performance.

Effects of aeration induced turbulence on colonial morphology and microcystin release of the bloom-forming cyanoabcterium Microcystis

Aeration induced turbulence was considered as an important measure to control the occurrence of cyanobacterial blooms in many lakes.Different aeration intensities were set for the culture of Microcystis aeruginosa based on the formation of Microcystis colony at high iron concentrations.The turbulent dissipation rate was calculated using a computational fluid dynamics(CFD)model to evaluate the intensity of turbulence.The effects of turbulence on the formation of Microcystis colony and the release of microcystin were analyzed.Results show that turbulence produced by aeration promoted the growth of Microcystis compared to that in stagnant water.Low intensity turbulence(4×10^(-8)-1×10^(-7) m2/s3)promoted the formation of Microcystis colonies,but high intensity turbulence(1.28×10^(-6)-1.8×10^(-5) m^(2)/s^(3))did not.The increase in the number of cells per colony was slower than that in total biomass,indicating that the low intensity turbulence induced colony formation via cell division,while the high level turbulence disaggregated colonies formed by both cell division and cell adhesion.Low aeration intensity induced more production of reactive oxygen species(ROS)and malondialdehyde(MDA)in the cells of Microcystis than those in high aeration intensity.In addition,the content of microcystin(MC)-LR in the cells was positively correlated with turbulence intensity,showing that turbulence affected not only the growth and aggregation of Microcystis colonies but also their toxin production.These findings provide a better understanding of the cyanobacterial bloom formation mechanisms and help to propose feasible methods to prevent the formation of Microcystis colonies in a natural environment.

Design and Experiment of Fluid Dynamic Ultrasonic Water Aerator

In order to improve the efficiency of water aerator,based on Venturi experimental principle in hydraulics and fluid dynamic ultrasonic generator,the inlet section,throat section,and outlet section of reed whistle ultrasonic generator were designed,and the effect of the water aerator on dissolved oxygen was preliminarily studied. Results indicate that using this water aerator,the dissolved oxygen was 7. 94 mg / L,exceeding the saturation value of dissolved oxygen( 7. 82 mg / L) at current water temperature,reaching the supersaturation. Therefore,the designed water aerator will have a bright application prospect in sewage treatment,aquaculture and aerated irrigation of plants.

Effect of bubble morphology and behavior on power consumption in non-Newtonian fluids’aeration process

Due to a prolonged operation time and low mass transfer efficiency, the primary challenge in the aeration process of non-Newtonian fluids is the high energy consumption, which is closely related to the form and rate of impeller, ventilation, rheological properties and bubble morphology in the reactor. In this perspective, through optimal computational fluid dynamics models and experiments, the relationship between power consumption, volumetric mass transfer rate(kLa) and initial bubble size(d0) was constructed to establish an efficient operation mode for the aeration process of non-Newtonian fluids. It was found that reducing the d0could significantly increase the oxygen mass transfer rate, resulting in an obvious decrease in the ventilation volume and impeller speed. When d0was regulated within 2-5 mm,an optimal kLa could be achieved, and 21% of power consumption could be saved, compared to the case of bubbles with a diameter of 10 mm.

Multimodal Machine Learning Guides Low Carbon Aeration Strategies in Urban Wastewater Treatment

The potential for reducing greenhouse gas(GHG)emissions and energy consumption in wastewater treatment can be realized through intelligent control,with machine learning(ML)and multimodality emerging as a promising solution.Here,we introduce an ML technique based on multimodal strategies,focusing specifically on intelligent aeration control in wastewater treatment plants(WWTPs).The generalization of the multimodal strategy is demonstrated on eight ML models.The results demonstrate that this multimodal strategy significantly enhances model indicators for ML in environmental science and the efficiency of aeration control,exhibiting exceptional performance and interpretability.Integrating random forest with visual models achieves the highest accuracy in forecasting aeration quantity in multimodal models,with a mean absolute percentage error of 4.4%and a coefficient of determination of 0.948.Practical testing in a full-scale plant reveals that the multimodal model can reduce operation costs by 19.8%compared to traditional fuzzy control methods.The potential application of these strategies in critical water science domains is discussed.To foster accessibility and promote widespread adoption,the multimodal ML models are freely available on GitHub,thereby eliminating technical barriers and encouraging the application of artificial intelligence in urban wastewater treatment.

Effect of surfactant frequently used in soil flushing on oxygen mass transfer in micro-nano-bubble aeration system

In-site soil flushing and aeration are the typical synergetic remediation technology for contaminated sites.The surfactant present in flushing solutions is bound to affect the aeration efficiency.The purpose of this study is to evaluate the effect of surfactant frequently used in soil flushing on the oxygen mass transfer in micro-nano-bubble(MNB)aeration system.Firstly,bio-surfactants and chemical surfactants were used to investigate their effects on Sauter mean diameter of bubble(dBS),gas holdup(ε),volumetric mass-transfer coefficient(kLa)and liquid-side mass-transfer coefficient(kL)in the MNB aeration system.Then,based upon the experimental results,the Sardeing's and Frossling's models were modified to describe the effect of surfactant on kL in the MNB aeration.The results showed that,for the twenty aqueous surfactant solutions,with the increase in surfactant concentration,the value of dBS,kLa and kL decreased,while the value ofεand gas-liquid interfacial area(a)increased.These phenomena were mainly attributed to the synergistic effects of immobile bubble surface and the suppression of coalescence in the surfactant solutions.In addition,with the presence of electric charge,MNBs in anionic surfactant solutions were smaller and higher in number than in non-ionic surfactant solutions.Furthermore,the accumulation of surfactant on the gas-liquid interface was more conspicuous for small MNB,so the reduction of kL in anionic surfactant solutions was larger than that in non-ionic surfactant solutions.Besides,the modified Frossling's model predicted the effect of surfactant on kL in MNB aeration system with reasonable accuracy.

曝气式搅拌强化含钒矿物金属元素的氧化和浸出研究

转炉钒渣和含钒废催化剂等二次资源是提钒的重要原料,但由于浸出过程中钒的氧化浸出受传质效率和气体扩散系数影响,浸出率难以进一步提高。因此,如何实现含钒矿相中低价钒的高效氧化对于钒的可持续性生产至关重要。以曝气式搅拌反应器作为浸出装置,通过流体力学计算模拟(CFD)研究了搅拌过程中气液混合分布规律,并将其应用于钒渣中钒、铬的液相氧化浸出过程。结果发现,曝气式搅拌有利于促进气液相混合均匀,并将气液混合相向反应器底部推进,增加气相停留时间,提高了后续氧化效率。通过曝气式搅拌,反应器内形成高密度的细微气泡,提高金属氧化效率,将钒渣中铬的氧化效率提高到98%以上。进一步通过EPR对浸出渣分析发现,曝气式搅拌可以直接促进固相钒铬尖晶石的氧化和分解,提高后续浸出效率。本研究通过CFD模拟和试验验证,为曝气式搅拌用于提高液相氧化浸出过程中低价金属的氧化和浸出效率提供依据,为实际搅拌釜的设计和操作提供了重要的参考价值。

增氧灌溉下配施硝化抑制剂对水稻生长、产量和氮肥利用的影响

【目的】明确增氧灌溉下配施硝化抑制剂对水稻生长、产量形成和氮肥利用的影响。【方法】以中浙优8号为材料,试验设常规淹水灌溉(Conventional Flood Irrigation,CF)和微纳米气泡水增氧灌溉(Micro-nano Bubble Water Oxygenation Irrigation,MB)2种灌溉模式,单施尿素(U)和尿素配施硝化抑制剂(Nitrification inhibitor,NI)2种氮肥处理。试验共设计4个处理:增氧灌溉下单施尿素(MB+U),增氧灌溉下尿素配施硝化抑制剂(MB+U+NI),淹水灌溉下单施尿素(CF+U),淹水灌溉下尿素配施硝化抑制剂(CF+U+NI)。分析了不同处理下水稻产量及其构成因子,水稻的茎蘖动态、叶面积指数和叶片叶绿素含量,不同生育期水稻茎、叶、穗各个部分氮累积量和水稻的氮素利用。【结果】增氧灌溉下施用硝化抑制剂能显著提高水稻产量,与淹水灌溉处理相比,增氧灌溉处理增幅为7.3%~10.0%;与单施尿素相比,配施硝化抑制剂各处理产量显著增加,增幅为2.9%~5.6%。各处理中增氧灌溉配施硝化抑制剂处理产量最高达到6756.4 kg/hm^(2)。从产量构成因子来看,增氧灌溉和添加硝化抑制剂主要影响了有效穗数和结实率,对每穗粒数和千粒重影响较小。处理MB+U+NI与处理CF+U相比,有效穗数提高了9.4%,结实率提高了11.0%。增氧灌溉下配施硝化抑制剂显著提高水稻的氮积累量。齐穗期处理MB+U+NI较处理CF+U的茎秆氮积累量和叶片氮积累量分别增加4.5%和6.1%。成熟期在相同氮肥处理下,增氧灌溉较淹水灌溉能提高穗氮积累量8.6%,总氮积累量9.3%;而在相同灌溉条件下,配施硝化抑制剂较单施尿素能提高穗氮积累量3.4%,总氮积累量2.9%。处理MB+U+NI较其他处理显著提高水稻的氮收获指数、氮素籽粒生产效率、氮肥偏生产力及氮素利用率。【结论】增氧灌溉下配施硝化抑制剂能促进水稻分蘖而提高有效穗数,有助于水稻干物质积累,促进后期灌浆,进而显著提高水稻结实率和产量,而且增加了水稻氮积累量从而提高水稻氮肥利用率。

MABR耦合AO工艺处理高原生活污水的研究

建立并启动MABR耦合AO工艺反应器,探讨耦合工艺对高原地区生活污水的处理效果。考察不同运行条件下耦合工艺对COD、氨氮和总氮的去除效果。结果表明:水力停留时间为24 h,硝化液回流比为200%,连续运行下耦合工艺对COD、总氮、氨氮的平均去除率分别为88.17%、71.35%、89.45%。通过微生物群落分析可知,改变水力停留时间和硝化液回流比对菌群丰度和多样性有所增加,生物膜内含有多种硝化及反硝化菌群,各菌群协同作用实现高效脱氮。

废弃加气混凝土基胶凝材料协同锂渣制备充填料的研究

针对工业固体废弃物堆存量大、资源化利用率低的问题,本工作尝试以废弃加气混凝土(WAC)、钢渣、矿渣、脱硫石膏、水泥为复合胶凝材料(CCMs),锂渣为细骨料,制备全尾砂绿色矿井充填料。采用粒度分析、力学性能测试、X射线衍射(XRD)及扫描电镜(SEM)等手段研究了WAC活性、充填料性能及CCMs水化机理。结果表明,粉磨40 min的WAC比表面积达到655 m^(2)/kg,其28 d活性指数为81.43%。当CCMs配合比为m(WAC)∶m(钢渣)∶m(矿渣)∶m(脱硫石膏)∶m(水泥)=20∶15∶38∶7∶20、充填料中m(CCMs)∶m(锂渣)=1∶7、料浆质量浓度为83%、m(NaCl)∶m(CCMs)=0.01,充填料3、28 d抗压强度分别为1.7、3.0 MPa。充填料用CCMs的主要水化产物为C-S-H凝胶、Ca(OH)2、钙矾石(AFt)、Friedel盐。

Nitrogen Release Kinetics and Nitrification-Denitrification on Surface Sediments under Aerating Disturbance Condition

[Objective] This study aimed to investigate the nitrogen release kinetics and nitrification-denitrification on surface sediments under aerating disturbance condition, with the purpose to solve the sediment nitrogen release and secondary pollution problems. [Method] The effect of in situ sediments aeration on the release of nitrogen pollutants was investigated, and the nitrogen release kinetics parameters were analyzed. The process of nitrification and denitrification under sediments aeration condition was investigated in laboratory. [Result] The nitrogen released from sediments was enhanced by aeration disturbance. The concentration of NH4＋-N and TN reached the maximum value in 30 min, and release rates were proportional to the disturbance strength. In this study, with the distance of aerator to the sediments surface of 0, 1, 2 and 3 cm, the suspended sediments concentrations were 3.52, 3.41, 3.26 and 3.01 g/L, respectively. Maximum release concentration of NH4＋-N and TN were 14.3, 13.8, 13.2, 12.2 mg/L and 33.21, 30.98, 29.83, 27.30 mg/L, respec- tively. In addition, both NH4＋-N and TN release kinetics could be described by Double Constant Equation as InC=A＋Blnt. Nitrification reaction occurred and was promoted by continued aerating to sediments.The concentration of NH4＋-N dropped down from 12.4 mg/L to 0.2 mg/L in 8 d, with the concentration of NO3--N increased to the maximum value of 10.8 mg/L. In addition, concentration of NO3--N and TN decreased from 10.8 mg/L and 37.4 mg/L to 0.36 mg/L and 23.2 mg/L after the stop of aeration for 12 d, indicating the occurrence of denitdfication reaction. Therefore, sediment aeration could accelerate nitrogen release and nitrification reaction, and with intermittent aeration, nitrogen could be removed from sediments in-situ by nitrification and denitrification. [Conclusion] The results provided technical reference for the in situ sediment remediation for the black-odor rivers in cities.

葡萄糖添加量与曝气时间对垂直潜流人工湿地脱氮的影响

【目的】探究葡萄糖添加量与间歇曝气时间对不同粒径级配基质填充垂直潜流人工湿地脱氮的影响。【方法】设置了2组试验,第1组试验设置了10、20、30 g葡萄糖外加碳源和细粒径、中粒径、粗粒径、正级配、反级配5种不同级配粒径沸石基质,研究葡萄糖添加量与沸石基质粒径对人工湿地脱氮的影响;基于第1组试验所得脱氮效果最佳的碳源及基质级配粒径组合,第2组试验研究了曝气0、2、4、6、8 h对人工湿地脱氮效果影响。【结果】葡萄糖添加量相同时,细粒径(2~4 mm)基质填充装置整体脱氮效果较好;粒径级配相同填充装置中,10g葡萄糖添加量处理的脱氮效果整体优于20、30g葡萄糖添加量处理;正级配、反级配基质填充的垂直潜流人工湿地装置的孔隙度减小程度最小;10g葡萄糖添加量、细粒径沸石基质填充装置的垂直潜流人工湿地脱氮效果最佳,TN的平均去除率达到50%左右。在此试验基础上,曝气时间为4 h时脱氮效果最佳,TN平均去除率达到86.9%。【结论】因此,添加10g葡萄糖且细粒径沸石基质填充的垂直潜流人工湿地曝气4h时脱氮效果最佳。

利用废弃加气砖粉末制备蒸压加气混凝土砌块

利用废弃加气砖粉末替代水泥石灰掺入蒸压加气混凝土砌块中,在温度为190℃、压力为1.3MPa的蒸压养护釜中养护9h后,蒸压砖的抗压强度能达到3MPa,略小于基准样,各项性能良好。经过微观机理分析后发现,废弃加气砖粉末单取代水泥量为30%时的蒸压加气混凝土砌块内部颗粒表面毛细气孔较少,属于微孔以下,内部颗粒堆积紧密;废弃加气砖粉末和水泥的交互作用显著,使蒸压砖内部结构更加致密,提高了蒸压砖的抗压强度。

钢渣在蒸压砂加气混凝土中的应用研究

钢渣是炼钢过程中的副产物,其活性低且体积安定性不良,这导致其综合利用率偏低,实现钢渣在建材行业的科学利用是其资源化的重要途径。以石英砂、石灰、钢渣、石膏和铝粉膏为主要原料,构建了蒸压加气混凝土料浆的基础配方,并研究了不同钢渣掺量(0%、10%、20%、30%)下AAC的各项物理性能,并采用X射线衍射分析和SEM对其微观性能进行一步探究。试验结果显示,随着钢渣掺量的增加,水灰比逐步下降,容重显著增加,而抗压强度则呈现先增后缓的趋势。XRD分析表明,蒸压后的AAC样品主要矿物相转变为石英、云母和托贝莫来石,且托贝莫来石的含量随钢渣掺量的增加而下降。微观形貌观察进一步证实了托贝莫来石形态的变化对蒸压加气混凝土性能的影响。因此,合理控制钢渣掺量对于优化蒸压加气混凝土生产工艺和提升产品性能具有重要意义,研究为实现钢渣的绿色大宗化利用提供了新的参考方式。

Effects of Aeration on Root Physiology and Nitrogen Metabolism in Rice

In order to clarify the effects of aeration on root nitrogen metabolism in rice seedlings,rice cultivars Guodao 6 （indica） and Xiushui 09 （japonica） were investigated for root growth,the activities of glutamine synthetase （GS）,glutamic acid-pyruvic acid transaminase （GPT） and glutamic acid oxaloacetate transaminase （GOT）,the nitrate （NO 3-N） concertration,the contents of free amino acids and soluble sugar in root under hydroponics with continuous aeration treatment.The results showed that rice seedlings grown in oxygenation solutions had higher root dry matter,longer root length,stronger root activity and larger root absorption area compared with the control.In addition,the contents of soluble sugar,root vigor and the activities of GS,GOT and GPT in the aeration solutions were higher than those in the control.The results also indicated that the activities of enzymes involved in root nitrogen metabolism of Xiushui 09 were enhanced by aeration,however,there was no significant influence on root nitrogen metabolism of Guodao 6,which suggested that effect of oxygenation on rice root nitrogen metabolism might be genotype-specific.