凋落物C/N对土壤有机碳矿化的影响

凋落物输入会影响土壤有机碳(SOC)矿化过程,其影响程度主要受凋落物C/N、土壤肥力和温度条件的影响,然而,这三因素的综合影响仍不清楚。以低肥力土壤(LF)和高肥力土壤(HF)为研究对象,分别添加7种不同C/N的凋落物,并设置培养温度为23℃和33℃,进行恒温避光培养,期间动态监测CO_(2)排放的变化,以揭示SOC矿化过程应对三因子的响应机制。结果显示,凋落物添加显著增加CO_(2)峰值排放速率,且与C/N>30的凋落物相比,添加C/N<30的凋落物对CO_(2)的峰值排放速率的促进作用更显著。CO_(2)峰值排放速率同时受土壤肥力和培养温度影响,HF-33℃条件下的CO_(2)峰值排放速率最高。添加C/N<30的凋落物显著增加了CO_(2)累积排放量,在LF-23℃、LF-33℃、HF-23℃和HF-33℃条件下,最大增幅分别为407%、304%、345%和160%。相关分析显示,SOC矿化率与凋落物C/N间呈负相关关系,这说明低质量凋落物会抑制SOC矿化。在LF-23℃、LF-33℃、HF-23℃和HF-33℃处理下,与凋落物C/N最低的CN1相比,添加C/N最高的CN7后,SOC矿化率的降幅分别达3.53、3.04、1.71和2.06倍。土壤肥力影响SOC矿化,HF的SOC矿化率较LF高1.29-2.66倍。培养温度对SOC矿化的影响在HF中表现出显著差异,与CK相比,在HF中添加凋落物显著降低了SOC矿化温度敏感性(Q10)。综合PLS-PM模型可知,SOC矿化是凋落物C/N、土壤肥力和培养温度综合作用的结果。其中,凋落物的C/N比对SOC矿化产生显著的负效应,土壤肥力则对SOC矿化产生主要的正效应,而温度的正效应则相对较小。研究结果有助于进一步理解不同土壤肥力和温度背景下,C/N不同的外源有机物输入对SOC矿化的影响及其背后的综合效应。

藻-菌颗粒污泥处理低C/N生活污水的研究

在光暗交替、零曝气条件下建立两组不同进水C/N(chemical oxygen demand,COD/total nitrogen,TN)(R_(1):10.0,R 2:5.6)的序批式反应器并运行了70 d,研究微藻-细菌颗粒污泥(microalgal-bacterial granular sludge,MBGS)在低C/N进水条件下的污染物去除效果、颗粒组成及稳定性的变化。研究发现,R^(1)组颗粒形态稳定,结构紧密,而R^(2)组颗粒形态出现差异化,结构略松散。R^(2)的COD去除率无显著变化,并且有更好的NH_(4)^(+)-N去除效果(94.68±7.24)%,但其PO_(4)^(3-)-P的去除效果不佳(50.69±13.64)%。通过元素分析进一步发现低C/N条件使MBGS中细菌的比例增加36%,并证明低C/N生活污水中的COD和PO_(4)^(3-)-P主要依靠MBGS的同化作用去除,NH_(4)^(+)-N主要被细菌的硝化作用转化。此外,低C/N组中蛋白质含量显著增加,并分泌更多的松散结合EPS(loosely bound EPS,LB-EPS)来提高颗粒稳定性。

Relationship Between Leaf C/N Ratio and Insecticidal Protein Expression in Bt Cotton as Affected by High Temperature and N Rate

Expression of insecticidal protein for transgenic Bacillus thuringiensis （Bt） cotton is unstable and related to nitrogen metabolism. The objective of this study was to investigate the relationship between leaf carbon nitrogen ratio （C/N） and insecticidal efficacy of two Bt cotton cultivars. C/N ratio and Bt protein content were both measured at peak square period and peak boll period respectively under 5-7 d high temperature and different nitrogen fertilizer rates on the Yangzhou University Farm and the Ludong Cotton Farm, China. All plants were grown in field. The results showed that the C/N ratio enhanced slightly and the Bt protein content remained stable at peak square period, but significant increases for the C/N ratio and decreases markedly for the leaf Bt protein concentration were detected at the peak boll period. The similar patterns at the two growth periods were found for the leaf C/N ratio and Bt protein content by different N fertilizer treatments. When nitrogen rate was from 0 to 600 kg ha-l, the C/N ratio was reduced by 0.017 and 0.006 for Sikang 1 and Sikang 3 at peak square period, compared to the 1.350 to 1.143 reduction for Sikang 1 and Sikang 3 at peak boll period, respectively. Correspondingly, the leaf Bt protein contents were bolstered by 2.6-11.8 and 26.9-36.9% at the two different growth periods, respectively. The results suggested that enhanced C/N ratio by high temperature and nitrogen application may result in the reduction of inseetiocidal efficacy in Bt cotton, especially in peak boll period.

Effect of carbon and nitrogen ratio control on Artemia growth, water quality, biofloc microbial diversity under high salinity and zero-water exchange culture condition

Biofloc technology has been applied successfully in the intensive aquaculture of several fish and shrimp species. The growth of heterotrophic microorganisms can be stimulated through adding extra carbon, which reduces the nitrogen level in the water and provides microbial protein to the animals. However, most of the studies and practical applications have been conducted in freshwater and marine environment. This paper focused on brine shrimp Artemia that lives in high salinity environment together with other halophilic or halotolerant microorganisms. The effect of carbon supplementation on Artemia growth, water quality, and microbial diversity of biofl ocs was studied in the closed culture condition without any water exchange. The salinity of the culture medium was 100. A 24-d culture trial was conducted through supplementing sucrose at carbon/nitrogen (C/N) ratio of 5, 15, and 30 (Su5, Su15, and Su30), respectively. The culture without adding sucrose was used as a control. Artemia was fed formulated feed at a feeding ration of 60% recommended feeding level. The results showed that sucrose supplementation at higher C/N ratio (15 and 30) signifi cantly improved the Artemia survival, growth and water quality ( P <0.05). Addition of sucrose at C/N ratio of 15 and 30 significantly increased biofloc volume (BFV)( P <0.05). The Illumina MiSeq sequencing analysis showed that supplementing carbon at C/N ratio of 15 had a better total bacterial diversity and richness, and shaped the microbial composition at genera level. This study should provide information for studying the mechanism of biofloc technology and its application in high salinity culture conditions.

Characteristics of Soil Organic Carbon, Total Nitrogen, and C/N Ratio in Chinese Apple Orchards

Soil organic carbon and nitrogen are used as indexes of soil quality assessment and sustainable land use management. At the same time, soil C/N ratio is a sensitive indicator of soil quality and for assessing the carbon and nitrogen nutrition balance of soils. We studied the characteristics of soil organic carbon and total nitrogen by investigating a large number of apple orchards in major apple production areas in China. High apple orchard soil organic carbon content was observed in the provinces of Heilongjiang, Xinjiang, and Yunnan, whereas low content was found in the provinces of Shandong, Henan, Hebei, and Shaanxi, with the values ranging between 6.44 and 7.76 g·kg-1. Similar to soil organic carbon, soil total nitrogen content also exhibited obvious differences in the 12 major apple producing provinces. Shandong apple orchard soil had the highest total nitrogen content (1.26 g·kg-1), followed by Beijing (1.23 g·kg-1). No significant difference was noted between these two regions, but their total nitrogen content was significantly higher than the other nine provinces, excluding Yunnan. The soil total nitrogen content for Xinjiang, Heilongjiang, Hebei, Henan, and Gansu was between 0.87 and 1.03 g·kg-1, which was significantly lower than that in Shandong and Beijing, but significantly higher than that in Liaoning, Shanxi, and Shaanxi. Six provinces exhibited apple orchard soil C/N ratio higher than 10, including Heilongjiang (15.42), Xinjiang (13.38), Ningxia (14.45), Liaoning (12.24), Yunnan (11.03), and Gansu (10.63). The soil C/N ratio was below 10 in the remaining six provinces, in which the highest was found in Shaanxi (9.47), followed by Beijing (8.98), Henan (7.99), and Shanxi (7.62), and the lowest was found in Hebei (6.80) and Shandong (6.05). Therefore, the improvement of soil organic carbon should be given more attention to increase the steady growth of soil C/N ratio.

Evaluation on nitrogen isotopes analysis in high-C/N-ratio plants using elemental analyzer/isotope ratio mass spectrometry

Elemental analyzer/isotope ratio mass spectrometry(EA/TRMS) has been widely applied to analyze the^(15)N/^(14)N isotope composition(δ^(15)N) of plants and soils,but the δ^(15)N results may be inaccurate due to incomplete combustion of the high-C/N-ratio plant samples by EA.Therefore,it is necessary to develop a method to solve the problem of imperfect combustion.In this study,we used two methods:1) adding copper oxide powder to the samples,and 2) increasing the O_2 flow(from 100 mL min^(-1) to 200 mL min^(-1)) for the auto sampler inlet purge line of the EA.The δ^(15)N values of the plant samples became more positive and tended to be stable after complete combustion.Also,the required blank samples for each plant sample decreased with increasing amount of the added CuO powder.However,at 200 mL min^(-1) of the oxygen flow in the EA,complete combustion could not be achieved without adding copper oxide,but this was done with decreased amount of CuO powder.Therefore,mixing cupric oxide into the high-C/N-ratio samples was an efficient,simple and convenient way to solve the problem of imperfect combustion in the EA.

Effects of Elevated CO_2 Concentration on the Biomasses and Nitrogen Concentrations in the Organs of Sainfoin(Onobrychis viciaefolia Scop.)

In forage grasses, the nitrogen concentration is directly related to the nutritional value. The studies examined the hypothesis that global elevation of CO2 concentration probably affects the biomass, nitrogen （N） concentration, and allocation and distribution patterns in the organs of forage grasses. While sainfoin （Onobrychis viciaefolia Scop.） seedlings grew on a low nutrient soil in closed chambers for 90 days, they were exposed to two CO2 concentrations （ambient or ambient＋350 μmol mol^-1 CO2） without adding nutrients to them. After 90 days exposure to CO2, the biomasses of leaves, stems, and roots, and N concentrations and contents of different parts were measured. Compared with the ambient CO2 concentration, the elevated CO2 concentration increased the total dry matter by 25.07%, mainly due to the root and leaf having positive response to the elevated CO2 concentration. However, the elevated CO2 concentration did not change the proportions of the dry matters in different parts and the total plants compared with the ambient CO2 concentration. The elevated CO2 concentration lowered the N concentrations of the plant parts. Because the dry matter was higher, the elevated CO2 concentration had no effect on the N content in the plants compared to the ambient CO2 concentration. The elevated CO2 concentration promoted N allocations of the different parts significantly and increased N allocation of the underground part. The results have confirmed the previous suggestions that the elevated CO2 concentration stimulates plant biomass production and decreases the N concentrations of the plant parts.

Influence of Different C/N Ratios on Aerobic Denitrification Characteristics of the Strain

[ Objective] The research aimed to study influence of different C/N ratios on aerobic denitdfication characteristics of the strain. [ Method] 5 aerobic denitdfying bacteria were isolated from activated sludge at low temperature and low C/N ratio, and their denitdfication capabilities were verified. Influence of different C/N ratios on denitdfication capability of the strain was determined. [ Result] In the five isolated aerobic denitdf- ying bacteria, except HFX08 was G-, HFX00, HFX01, HFX12 and HFX13 were G ＋. HFX08 belonged to Pseudomonas, and other strains be- longed to Acinetobacter. As C/N ratio increased, denitdfication velocity increased, and the highest removal rate of nitrogen for the five strains could reach over 92%. [ Conclusion] The research could provide reference for design and operation of the sewage treatment process with low C/N ratio in winter in the north.

Amelioration of Saline Soil by the Application of Gypsum, Calcium Chloride, Rice Husk and Cow Dung

A pot experiment was conducted to investigate the effect of cow dung, rice husks, calcium chloride and gypsum on soil reclamation and compare the effect of organic and inorganic amendments on soil reclamation during the period of 5th March to 20th April, 2017. The experiment was laid to fit a completely randomized design (CRD) with seven treatments [Reference soil (T0), Cow dung (T1), Rice husk (T2), Gypsum (T3), Calcium chloride (T4), Cow dung + Rice husk (T5) and Gypsum + Calcium chloride (T6)] each having three replications for this experiment. After incubation (45 days), the laboratory investigation was carried out in the Soil, Water and Environment Discipline, Khulna University, Khulna, Bangladesh. Results indicate that the individual or combined effect of gypsum (T3) was more effective in changing EC and SAR. Gypsum application in combination with calcium chloride (T6) improved the soil chemical properties by reducing the EC. Among the treatment, calcium chloride (T4) had a remarkable effect in reducing sodium adsorption ratio and gypsum had a remarkable effect in reducing pH. Cow dung (T1), rice husk (T2), combination of cow dung and rice husk (T5) were less effective to reduce EC, pH and SAR. It’s measured for soils of different soil amendments varied significantly

IL-6、CRP、NLR和NT-proBNP对老年心力衰竭合并肺炎的诊断价值

目的探讨白细胞介素-6(IL-6)、C-反应蛋白(CRP)、中性粒细胞与淋巴细胞比值(NLR)和N末端前脑钠肽前体(NT-proBNP)对老年心力衰竭(以下简称心衰)合并肺炎的诊断价值。方法选取2022年4月至2023年4月该院收治的165例老年心衰患者作为研究对象,根据是否合并肺炎分为心衰合并肺炎组(78例)和单纯心衰组(87例),根据美国纽约心脏病协会(NYHA)心功能分级标准分为Ⅱ级组(59例)和Ⅲ级+Ⅳ级组(106例)。比较各组IL-6、CRP、NT-proBNP水平和NLR;采用Spearman相关分析IL-6、CRP、NLR与NT-proBNP水平的相关性;采用受试者工作特征(ROC)曲线评估IL-6、CRP、NLR、NT-proBNP单独及联合检测对心衰患者合并肺炎的诊断效能。结果心衰合并肺炎组IL-6、CRP、NT-proBNP水平及NLR明显高于单纯心衰组(P<0.05),Ⅲ级+Ⅳ级组IL-6、CRP、NT-proBNP水平及NLR明显高于Ⅱ级组(P<0.05)。Spearman相关性分析结果显示,NT-proBNP水平与IL-6、CRP、NLR水平呈正相关(r=0.263、0.419、0.468,P<0.001)。IL-6、CRP、NLR和NTproBNP联合诊断心衰合并肺炎的曲线下面积(AUC)为0.726(95%CI:0.650~0.803),灵敏度为67.9%,特异度为71.3%。结论心衰合并肺炎患者IL-6、CRP、NT-proBNP水平和NLR明显高于单纯心衰患者,上述4项指标联合检测对心衰合并肺炎患者有一定的诊断效能。

不同碳氮比(C/N)等单因素对反硝化除磷菌脱氮除磷性能的影响分析

对污水处理中反硝化除磷菌在不同碳氮比(C/N)及其他环境因素(如pH、溶解氧、温度)影响下的脱氮除磷性能进行深入分析。从菌种选择与培养、模拟废水配置、实验设计与数据分析等方面进行论述,旨在揭示碳氮比及上述环境因素如何调控脱氮除磷过程。提出基于实验数据的优化策略,以及相应的数学模型,用于预测不同参数对脱氮除磷效率的具体影响。此研究达到提高污水处理效率和降低运营成本的效果,解决现有污水处理技术中脱氮除磷过程效率低下和环境因素影响不明确的问题。通过系统的实验方法和详尽的数据分析,为污水处理系统的设计和操作优化提供科学依据和实践指导,推动污水处理技术的发展与环境保护事业的进步。

Effects of Soil C/N Ratio on Apple Growth and Nitrogen Utilization,Residue and Loss

Soil C /N ratio is an important influencing factor in soil nitrogen cycling. Two-year old apple trees( Borkh. cv. ‘Fuji'/Malus hupehensis) were used to understand the effect of soil C/N ratio [6. 52( CK),10,15,20,25,30,35 and 40]on apple growth and nitrogen utilization and loss by using15N trace technique. The results showed that,with the increasing of soil C/N ratio,apple shoot length and fresh weight increased at first,and then decreased; the higher apple shoot length and fresh weight appeared in C/N = 15,20 and 25 treatments,and there were no significant differences among these three treatments,but significantly higher than the other treatments. Statistical analysis revealed that there was significant difference in nitrogen utilization rate between the different treatments,the highest N utilization rate was occurred in soil C/N = 25 treatment which value was 22. 87%,and there was no significant difference between soil C/N = 25 and C/N = 20 treatments,but both the two treatments were significantly higher than the other treatments; Soil C/N = 40 had the lowest N utilization rate which value was 15. 43%,and this value was less than CK( 16. 65%). The proportion of plant absorption nitrogen from fertilizer was much higher when the value of soil C/N ratio in the range of 15- 25,but the percentage of plant absorption nitrogen from soil was much higher when the soil C/N ratio was too low( < 15) or high( < 25). Amount of residual nitrogen in soil increased gradually with the soil C/N ratio increasing,the amount of residual nitrogen in C/N = 40 treatment was 1. 32 times than that in CK. With the increasing of soil C/N ratio,fertilizer nitrogen loss decreased at first,and then increased,fertilizer nitrogen loss was the minimum in C/N = 25 treatments( 49. 87%) and the maximum were occurred in CK( 61. 54%). Therefore,regarding the apple growth and nitrogen balance situation,the value of soil C/N ratio in the range of 15- 25 would be favorable for apple growth and could increase effectively nitrogen fixed by soil,reduce nitrogen loss,and improve the nitrogen utilization ratio.

Effect of C/N Ratio on DHA Production by Schizochytrium sp.JN-3 and Its Pilot-scale Fermentation

[ Objective] This study aimed to explore the effect of C/N ratio on DHA production by Schizochytrium sp. , and the results were verified by pilot-scale fermentation. [ Method] Effect of C/N ratio on DHA production by Schizochytrium sp. JN-3 was explored. The industrial fermentation potential of Schizochytrium sp. JN-3 was investigated by pilot-scale fermentation in a 200 L fermentation tank. [ Result] Results of fermentation in a 7 L fermentation tank showed that the maximum biomass and total lipid content were 34.3 and 20.1 g/L, respectively, when C/N ratio was 10 ; the maximum DHA yield was 46.9% when C/N ratio was 20. When pilot-scale fermentation was conducted in a 200 L fermentation tank, the biomass was 30. 2 g/L, total lipid content was 18.4 g/L, accounting for 63.2% of the dry weight of cells; DHA content was 7.4 g/L, accounting for 40. 2% of the total lipid content. [ Condasion ] Schizochytrlum sp. JN-3 has good industrial fermentation notential.

臭氧胁迫对水稻生长以及C、N、S元素分配的影响

采用开顶式气室(Open-top Chamber,OTC),对水稻"3694繁"(Oryza sativa L.,3694 Fan)在浙江嘉兴进行田间原位臭氧(O3)熏气实验,研究不同臭氧浓度熏气对水稻生长以及C、N、S元素分配的影响。实验设置分4个水平:过滤大气组(CF,10nL/L)、自然大气组(NF,40 nL/L)和两个不同浓度的臭氧处理组(O3-1:100 nL/L;O3-2:150 nL/L)。主要结果表明:(1)开始臭氧熏气时,各个处理组单茎水稻各组分生物量没有差异.在熏气后期(水稻成熟期),臭氧处理使单茎水稻根、茎和穗生物量显著下降,根冠比降低,株高显著降低,表明臭氧胁迫增加水稻地上部分的干物质分配,且对株高的影响可能大于对地上生物量的影响;(2)臭氧处理使水稻根和茎C元素含量下降,叶C元素含量上升,表明臭氧胁迫提高了叶片中碳分配,而降低了根和茎的碳分配;(3)各个组分N元素含量上升和碳氮比下降;(4)茎、叶和穗S元素含量上升,可能会增强水稻抗氧化系统的作用,从而抵抗臭氧胁迫。所有实验结果表明臭氧浓度升高会对水稻生长产生严重不利影响,从而导致水稻各个组分的C、N、S元素分配格局发生改变。

不同C N比堆肥碳素物质变化规律研究

针对堆肥化过程中常伴有少量CH4等温室气体排放造成环境污染等问题,采用密闭堆肥化装置,进行了不同碳氮比和通气条件下,堆肥过程中的气体释放规律、影响因子及其对堆肥理化性质的影响研究。结果表明,C/N=25、30堆肥处理的有机物降解率高于低碳氮比处理;全氮含量随着有机物的降解而浓缩,随着堆肥的进行而不断提高,到堆肥结束时,C/N=15、20、25和30处理的全氮含量分别为23.5、24、27.8 g.kg-1和28.4 g.kg-1;堆肥过程中,C/N=15、20、25和30的堆肥处理CH4累积排放为0.67、0.95、2.25g.kg-1和1.80 g.kg-1,损失比例占初始碳物质的0.39%、0.5%、1.24%和0.92%,并且CH4气体的排放主要集中在高温前期,高温期越长,排放的温室气体越多。高温期适当增大通气量,对于控制堆肥温度和减少温室气体生成有双重作用。

不同C/N比对堆肥腐熟度和含氮气体排放变化的影响

NH3和N2O等含氮气体的排放不仅对堆肥腐熟度和堆肥产品的品质产生影响,同时也与环境污染有直接关系。本研究以猪粪和玉米秸秆为堆肥原料,采用好氧堆肥的方法,探讨了不同C/N比对堆肥腐熟度及NH3和N2O等含氮气体排放变化的影响。结果表明,C/N比为15、20、25和30处理的高温期持续时间分别为2、5、13和12d;C/N比为25处理的堆肥积温最高,达21331℃.h,较C/N比为15、20和30处理的堆肥积温分别提高了89.3%、21.9%和7.14%。堆肥结束时,各处理的全碳降解率以C/N比为25的最大,达24.55%;全氮含量除C/N比15下降了9%之外,其他堆肥处理均较堆制前有明显提高;除C/N比为15堆肥的种子发芽率未达到腐熟外,其他3个处理腐熟度指标均达到要求。氨气累积释放量随C/N比的升高依次降低;各处理N2O的排放量差异不大,堆肥高温期N2O排放通量最大,随着堆肥的进行,排放量逐渐减少。

同步硝化反硝化SBBR处理低C/N比生活污水的启动与稳定运行

以低C/N比实际生活污水为处理对象,聚氨酯海绵填料为生物载体(填料填充率25%),采用逐步提高氮负荷的方式,在较短的时间内(98 d)成功启动了同步硝化反硝化(simultaneous nitrification and denitrification,SND)的序批式生物膜反应器(sequencing batch biofilm reactor,SBBR)。实时定量PCR(real-time qualitative polymerase chain reaction,real-time q PCR)结果表明系统内硝化菌得到富集。在稳定运行期间,系统对有机物及氮的去除效果良好,平均出水COD、4NH-N+、TN分别为38.28 mg·L-1、1.23 mg·L-1、8.23 mg·L-1。微生物将大部分碳源以聚羟基脂肪酸酯(poly-β-hydroxyalkanoate,PHA)的形式储存至体内,系统内3NO-N-的去除主要通过内源反硝化作用,且反硝化过程基本无2NO-N-积累,平均SND率为70.57%,TN去除率高达82.95%。由于硝化反应和反硝化反应在同一反应器内同时进行,反硝化过程产生的碱度可补充硝化过程消耗的碱度,维持系统内p H的相对稳定。此外,可以通过DO和p H的变化判断SND的进行状态,有效地控制反应时间,节省动力消耗。

C/N比对嗜酸细菌X-29产氢能力及其酶活性的影响

C/N比影响细菌的物质和能量代谢,为了提高产氢细菌的产氢效能,通过间歇产氢实验和酶活性分析方法,分析了在不同C/N比下嗜酸产氢细菌X-29的产氢能力以及氢化酶和乙醇脱氢酶的活性表达情况.研究结果表明,C/N比对产氢细菌的代谢及其相关酶的表达有显著的影响.虽然在不同C/N比下单位生物量的液相末端发酵产物差异不大,但是产氢能力存在显著的差异,当C/N比为14时产氢细菌X-29具有最大累积产氢量2 210.9mL/g.在不同C/N比下氢化酶的表达活性不同,氢化酶活性随着发酵的进行达到高峰后迅速降低,氢化酶的表达周期较短.乙醇脱氢酶活性随着代谢进程逐渐升高后而趋于平稳,不同C/N比时表达活性差异较小,表达周期较长.在C/N比为14时,氢化酶和乙醇脱氢酶的活性最高,分别为2.8μmol.(min.mg)-1和33.2μmol.(min.mg)-1.

DO C/N对同步硝化反硝化影响的试验研究

在序批式活性污泥反应器(SBR)内,以模拟的城市污水为处理对象,研究DO、C/N等因素对同步硝化反硝化脱氮效率的影响。研究表明:采用连续曝气工艺,在进水COD=200mg/L,NH4+-N=30mg/L条件下,控制DO在0.5～1.5mg/L范围内时,出水TN浓度为1.98～6.3mg/L,TN的平均去除率在80%以上,最高去除率达到93.74%,并可推断出在反应系统内存在好氧反硝化菌;C/N在3.3～10之间时,C/N越高,出水NO3--N浓度越低,SND效果越好。

土壤C/N比对烤烟碳氮代谢关键酶活性和烟叶品质影响的研究

2009年采用盆栽试验,在河南农业大学科教园区通过添加腐熟的小麦秸秆来调节土壤的碳氮比,进而研究土壤碳氮比对烤烟碳氮代谢关键酶活性和烟叶品质的影响。结果表明：随着土壤碳氮比的增加,硝酸还原酶、转化酶和淀粉酶的活性逐渐增加,烤后烟叶总糖和还原糖的含量、中性香气物质的总量、还原糖/烟碱有不同程度的增加,烟碱、总氮含量以及氮碱比逐渐减少。土壤碳氮比在24~28之间时,有利于促进烤烟碳氮代谢平衡,协调烤后烟叶化学成分。