Transformation of Carbon and Nitrogen by Earthworms in the Decomposition Processes of Broad-leaved Litters

Earthworms are the important constituents in the decayed food web and the main ecological conditioners in the process of decomposition and nutrient mineralization. The transformation of organic carbon (C) and total nitrogen (N) in the broad-leaved litters ingested by earthworms was researched by means of a laboratory experiment. Experimental samples were collected from broad-leaved Korea Pine mixed forest in Liangshui National Natural Reserve (47°10′50″N, 128°53′20″E) in the northeastern Xiao Hinggan Mountains of Northeast China. The contents of organic C and total N in earthworms, leaf litters and earthworm faeces were analyzed. Results show that the organic C content was in the fol- lowing order: leaf litters>faeces>earthworms, while total N content was contrary to that of the organic C. The organic C contents in the different leaf litters were in the following order: Tilia amurensis>Betula costata>Acer mono, whereas the total N contents in the different leaf litters were: Betula costata>Tilia amurensis>Acer mono. The contents of organic C and total N in the faeces from the different leaf litters were almost consistent with the contents of the leaf litters. After the leaf litters were ingested by earthworms, the organic C, which was transformed to increase earthworms' weights, ac- counted for 3.90%-13.31% of the total ingestion by earthworms, while that in the earthworm faeces accounted for 6.14%-13.70%. The transformed organic C through the other metabolism (e.g., respiration) of earthworms accounted for 75.04%-89.92%. The ingested organic C by earthworms was mostly used for metabolic activities. The N ingested by earthworms was less than organic C. It is estimated that 37.08% of total N was transformed to increase the earthworm's weight, 19.97% into earthworm faeces and 47.86% for the consumption of the earthworm's activities. The earthworms not only increased the content of organic C and total N in the soil, but also decreased the values of C/N in the soil and leaf litters. Earthworms play a major role in the leaf litters' decomposition and transformation.

Megacity pathways in China under the dual carbon goal:The case of Shanghai

The pathways to achieving carbon neutrality at the city level are diverse due to varying energy supply and demand conditions.Shanghai faces obstacles such as limited land resources,high costs of renewable energy technologies,and instability of renewable energy.These challenges hinder the city’s efforts to achieve carbon peak and carbon neutrality(dual carbon).Therefore,Shanghai must identify and optimize its development path for renewable energy under the dual carbon goal.We employed the Low Emissions Analysis Platform Shanghai(LEAP-SH)model to simulate the impact of policies,such as industrial upgrading,energy efficiency improvement,energy structure optimization,increased technical innovation on energy,and ecological restoration,on the carbon emission pathways from 2022 to 2060 using five different scenarios.Our results indicate that Shanghai has the potential to achieve carbon neutrality in 2059 by promoting carbon reduction,pollution control,and green expansion.Moreover,we determined that the manufacturing industry;power generation industry;and transportation,storage,and mail services are the three major sectors for emission reduction under the dual carbon goal.Furthermore,the capacity and output of coal-fired power plants will be gradually replaced by offshore wind power in the dual carbon pathway.Finally,this study proposes countermeasures and suggestions for Shanghai to attain the dual carbon goal and high-quality development.

Interfacial engineering of graphitic carbon nitride(g-C_3N_4)-based metal sulfide heterojunction photocatalysts for energy conversion: A review

As one of the most appealing and attractive technologies, photocatalysis is widely used as a promising method to circumvent the environmental and energy problems. Due to its chemical stability and unique physicochemical, graphitic carbon nitride (g-C3N4) has become research hotspots in the community. However, g-C3N4 photocatalyst still suffers from many problems, resulting in unsatisfactory photocatalytic activity such as low specific surface area, high charge recombination and insufficient visible light utilization. Since 2009, g-C3N4-based heterostructures have attracted the attention of scientists worldwide for their greatly enhanced photocatalytic performance. Overall, this review summarizes the recent advances of g-C3N4-based nanocomposites modified with transition metal sulfide (TMS), including (1) preparation of pristine g-C3N4,(2) modification strategies of g-C3N4,(3) design principles of TMS-modified g-C3N4 heterostructured photocatalysts, and (4) applications in energy conversion. What is more, the characteristics and transfer mechanisms of each classification of the metal sulfide heterojunction system will be critically reviewed, spanning from the following categories:(1) Type I heterojunction,(2) Type II heterojunction,(3) p-n heterojunction,(4) Schottky junction and (5) Z-scheme heterojunction. Apart from that, the application of g-C3N4-based heterostructured photocatalysts in H2 evolution, CO2 reduction, N2 fixation and pollutant degradation will also be systematically presented. Last but not least, this review will conclude with invigorating perspectives, limitations and prospects for further advancing g-C3N4-based heterostructured photocatalysts toward practical benefits for a sustainable future.

Optimization of C/N ratio preparation of protein-rich and multi-enzymes feed thallus through synergic fermentation of mixed distillers'grains

A new procedure of determining optimal C/N (the rate of carbon source to nitrogen source) of mixed distillers' grains for combined bacteria synergic fermentation is established. At the same time an improved method evaluating bacteria growth, called method of dry cell weighing by filtering is developed. For each combination of C and N, their initial and residual contents before and after fermentation respectively are determined. Then followed the calculation of utilization of C and N sources by the compound bacteria. The optimal C/N is finally located from among the utilization of C and N of several combinations and the weight of produced mass of oven dried thallus. The conditions of fermentation are: inoculum size 10%, temperature 30 0℃, rotational speed 170 r/min, shake culture time 48h. The best results obtained from orthogonal experiments are: maximum mass of oven dried thallus is 14 693g in a liter liquid medium, maximum utilization rate of carbon source is 98 13% and maximum utilization rate of nitrogen is 78 14%. Optimal C/N is 5 1.

Effect of Acetylene Concentration on Denitriflcation and Related Microbial Processes in Anaerobically incubated Soil Slnrries

In order to study the influence of difference in C2H2 concentration on the production of CO2, N2O,NH4-N and volatile fatty acids （VFA）, soil slurries with a gradient in C2H2 concentration were anaerobicallyincubated at 25°C for 2 weeks. Acetate, butyrate and CO2 production and NH4-N accumulation wereinhibited in the slurries in the presence of C2H2; and the inhibition effect increased with increasing C2H2from 0 to 20 kpa in the headspace gas of the incubation bottle. However, N2O, isobutyrate and propionateproduction was not obviously different among the slurries amended with C2H2 from 2.5 to 20 kpa. Therefore,the results implied that the C2H2 did not promote the inhibition but only increased the side effect onother microbial processes. The C2H2 of 2.5 kpa was suggested to be the optimum choice for the presentdenitrification study.

Elevated atmospheric CO_(2) impact on carbon and nitrogen transformations and microbial community in replicated wetland

Background:Elevated atmospheric CO_(2) has direct and indirect influences on ecosystem processes.The impact of elevated atmospheric CO_(2) concentration on carbon and nitrogen transformations,together with the microbial community,was evaluated with water hyacinth(Eichhornia crassipes)in an open-top chamber replicated wetland.The responses of nitrogen and carbon pools in water and wetland soil,and microbial community abundance were studied under ambient CO_(2) and elevated CO_(2)(ambient+200μL L^(−1)).Results:Total biomass for the whole plant under elevated CO_(2) increased by an average of 8%(p=0.022).Wetlands,with water hyacinth,showed a significant increase in total carbon and total organic carbon in water by 7%(p=0.001)and 21%(p=0.001),respectively,under elevated CO_(2) compared to that of ambient CO_(2).Increase in dissolved carbon in water correlates with the presence of wetland plants since the water hyacinth can directly exchange CO_(2) from the atmosphere to water by the upper epidermis of leaves.Also,the enrichment CO_(2) showed an increase in total carbon and total organic carbon concentration in wetland soil by 3%(p=0.344)and 6%(p=0.008),respectively.The total nitrogen content in water increased by 26%(p=0.0001),while total nitrogen in wetland soil pool under CO_(2) enrichment decreased by 9%(p=0.011)due to increased soil microbial community abundance,extracted by phospholipid fatty acids,which was 25%larger in amount than that of the ambient treatment.Conclusion:The study revealed that the elevated CO_(2) would affect the carbon and nitrogen transformations in wetland plant,water,and soil pool and increase soil microbial community abundance.

Determining nitrogen fate by hydrological pathways and impact on carbonate weathering in an agricultural karst watershed

Identifying the nitrogen(N)fate is complicated and a great challenge in karst watersheds because of the co-existence of natural pools and anthropogenic sources.The objective of the study was to use stable isotopic composition of dual-isotope(δ^(15)NNitrate and δ^(18)O_(Nitrate))and LOADEST model approaches to trace N sources,pathways in karst watershed.The study was conducted in the Houzhai watershed,which is a typical agricultural karst watershed from July 2016 to August 2018,to reveal the N fate and the coupled carbon(C)-N processes occurring in the riverine-watershed with agricultural activities.We found that the wet deposition of total nitrogen(TN)flux was 33.50 kg hm^(-2)·a^(-1)and dissolved nitrogen(DN)flux was 21.66 kg hm^(-2)·a^(-1).The DN runoff loss was 2.10×10^(5)kg·a^(-1)and the loss of DN during the wet season accounted for 95.4%over a year.In the wet season,NO_(3)^(-)-N daily efflux was 977.62±516.66 kg ha^(-1)·day^(-1)and 248.77±57.83 kg ha^(-1)·day^(-1)in the dry season.The NH_(4)^(+)-N efflux was 29.17±10.50 kg ha^(-1)·day^(-1)and 4.42±3.07 kg ha^(-1)·day^(-1)in the wet and dry seasons,respectively.The main form output load of N was NO_(3)^(-)-N which was more than 30 times as much as NH_(4)^(+)-N output loss.The NO_(3)^(-)N caused by rainfall contributed11.82%-53.61%to the export load.Nitrate from soil contributed over 94%of the N to Houzhai river caused by N leaching.In addition,manure and farmland soil were the main sources of groundwater in the Houzhai watersheds,the contribution rates were 25.9%and 22.5%.The chemical N fertilizers affected carbonate weathering strongly,and the HCO_(3)^(-) flux caused by nitrifi-cation due to N fertilizers application in soil accounted for 23.5%of the entire watershed.This study suggested that carbonate weathering may be influenced by nitrogen nitrification in the karst watershed.

牛粪对双孢菇菌渣堆肥过程中碳氮转化及真菌群落的影响

为揭示牛粪对双孢菇菌渣堆肥过程中真菌群落动态及其对碳氮转化的影响,使用高通量测序技术探索了牛粪和菌渣堆肥过程中真菌群落组成、结构的变化,利用生物信息学的方法分析了真菌群落及其与碳、氮组分间的相互作用关系。以牛粪和菌渣作为研究对象,采用条垛式堆肥的方法共堆肥42 d,设CK(100%双孢菇菌渣)和CD(双孢菇菌渣∶牛粪=7∶3)两个处理。结果表明:CD处理比CK堆肥总有机碳(TOC)降低2.17%,腐熟期碳、氮分别提高48.69%和4.01%,发芽指数(GI)提高49.33%。添加牛粪提高了菌渣堆肥中真菌群落丰富度和多样性,堆体温度高且高温期延长23 d;子囊菌门和担子菌门是两处理的优势菌门;CD处理食线虫菌属(Duddingtonia)、Coprinellus、鬼伞属(Coprinopsis)、细粒嗜热菌属(Thermomyces)的相对丰度均高于CK,有利于碳氮转化。利用Pearson相关系数构建网络模型,分析筛选出与碳氮转化相关的核心真菌属,CD处理有2个与TOC相关的核心真菌属(50%正相关),CK处理中有7个属与TOC相关(28.6%正相关)。菌渣牛粪联合堆肥真菌共现网络的关联性和复杂性更高,真菌群落间竞争减弱,平均路径长度较低,网络更敏感。菌渣堆肥添加牛粪可改变核心真菌与TOC和总氮(TN)间的关系,在CD处理中TOC核心菌与TOC呈正相关,而在CK处理中呈负相关。两处理TN核心菌与TN间均呈显著正相关关系,与TOC负相关。研究表明,菌渣与牛粪联合可使堆体快速升温,延长堆体的高温期,核心真菌通过增加与其他微生物的相互作用,影响碳氮转化,降低TOC损失率,提高堆肥品质。

Phosphorus-doping activates carbon nanotubes for efficient electroreduction of nitrogen to ammonia

The electrochemical nitrogen reduction reaction(NRR)as an energy-efficient approach for ammonia synthesis is hampered by the low ammonia yield and ambiguous reaction mechanism.Herein,phosphorus-doped carbon nanotube(P-CNTs)is developed as an efficient metal-free electrocatalyst for NRR with a remarkable NH3 yield of 24.4μg·h^−1·mg^−1cat.and partial current density of 0.61 mA·cm^−2.Such superior activity is found to be from P doping and highly conjugated CNTs substrate.Experimental and theoretical investigations discover that the electron-deficient phosphorus sites with Lewis acidity should be genuine active sites and NRR on P-CNTs follows the distal pathway.These findings provide insightful understanding on NRR processes on P-CNTs,opening up opportunities for the rational design of highly-active cost-effective metal-free catalysts for electrochemical ammonia synthesis.

海洋平台制氮系统节能降耗改造升级方案与实施

海上某油田依托平台公用气系统为生产流程持续输送纯净氮气,在制氮过程中,由于该油田制氮系统一直消耗大量公用气,空气压缩机频繁加载,加重公用气系统负荷,导致空压机排气高温报警关停,既影响公用气系统的稳定性,也降低机组的使用寿命。在膜分离系统前增加气动阀,根据氮气罐压力的高低进行开关,进而控制用于制氮的公用气的通断。通过改造升级,有效避免空压机长时间加载运转,降低制氮系统的耗能及对公用气的消耗,切实提高了平台公用气系统的稳定性。

碳含量对再生水灌溉土壤氮素迁移转化规律的影响

为深入了解碳含量对再生水灌溉系统中氮素迁移转化的影响,该研究进行了碳含量影响下的再生水灌溉系统氮素迁移转化规律试验。利用不同碳含量的再生水灌溉种植在土柱中的黑麦草,测定各试验周期内灌溉水、土壤溶液和排水中不同形态氮的含量,分析不同生育期作物干物质产量和氮含量。结果表明,随灌溉水进入系统的氮素约有34%可被作物吸收利用,62%可通过反硝化作用去除或调节土壤氮库中的氮量,随水分下渗到根系层以下并随排水排出系统的氮量仅占灌溉水中氮量的3%～4%。从作物长势、干物质量和氮的利用量看,高碳处理优于低碳处理。试验条件下,再生水中碳含量较高时有利于氮素的转化、作物吸收利用以及氮的反硝化作用。研究结果对于以灌溉利用为目的的污水处理,具有一定的指导意义。

冷轧301L奥氏体不锈钢的变形和应变硬化行为

研究了SUS301L和CN301L奥氏体不锈钢HT(high tensile,4/4H)和DLT(deadline tensile,1/4H)两个硬化等级冷轧板材的变形和应变硬化行为及其应变诱发α′马氏体转变.所有301L冷轧板拉伸试样近断口处都发生了85%以上的马氏体相变,轧制变形量增加,室温拉伸应变诱发马氏体转变开始的应变减小,但未增加马氏体转变饱和值.CN301L中C和N的含量高于相同硬化等级的SUS301L,导致它们变形和硬化行为不同.C和N的含量较高,对γ相和α′相的固溶强化效果增强,冷轧奥氏体不锈钢无需发生大量马氏体转变就能达到要求的高屈服强度,保证冷轧板材具有较好的塑性和一定的成型能力;此外,形成的应变诱发马氏体中,C和N的固溶度大,硬化效果增强,流变应力上升快,抗拉强度高;C和N含量较高,还增加奥氏体的稳定性,将拉伸过程中应变诱发马氏体转变推迟到较高应变发生,延长应变硬化行为的第二阶段,增强相变增塑效应.

凤眼莲根系分泌氧和有机碳规律及其对水体氮转化影响的研究

通过模拟实验,研究凤眼莲不同苗龄根系分泌氧及有机碳的规律,在此基础上分析凤眼莲根系分泌氧和有机碳对富营养化水体溶解氧、有机碳及无机氮(NH+4和NO-3)转化的影响。研究结果表明凤眼莲根系具有较强的泌氧及分泌有机碳的能力,小、中、大三个苗龄凤眼莲根系泌氧速率分别达56.19、93.15、106.32μmolO2·h-1,根系分泌有机碳的速率分别达0.25、0.60、0.92 mg·L-1·h-1。不同苗龄凤眼莲根系泌氧及有机碳的速率随苗龄的增加显著升高,而其相对应的单位根系泌氧和有机碳的能力随苗龄的增加呈降低趋势。水体中无机氮的去除率随着凤眼莲苗龄的增加而增加,这除了与凤眼莲的吸收作用有关外,还因为其泌氧和分泌有机碳的总量增加加强了硝化和硝化-反硝化过程的潜力,从而高效并快速地净化水体中外源氮负荷。

中亚热带森林转换对土壤可溶性有机质数量与光谱学特征的影响

选取中亚热带福建三明格氏栲天然林及其转换而成的木荷、锥栗及福建柏等3种人工林表层土壤(0—10 cm)可溶性有机质(DOM)为对象,对其数量和光谱学特征进行了研究,以探讨森林转换对土壤DOM的影响。结果表明,天然林转换成上述3种人工林后,0—5 cm土壤可溶性有机碳(DOC)浓度显著降低(P<0.05),降低程度分别为66.1%,69.9%及29.4%,可溶性有机氮(DON)浓度也有所下降;除福建柏外,其余两种人工林5—10 cm土壤DOC及DON浓度均低于天然林。各林分0—5 cm土壤DOC及DON浓度均高于5—10 cm土层。两个土层中,天然林土壤DOM的芳香化及腐殖化程度均显著高于人工林(P<0.05),但荧光效率值低于人工林;荧光光谱图显示,天然林土壤DOM在芳香性脂肪族及木质素类复杂结构荧光基团处的吸收大于人工林;各林分土壤DOM傅里叶红外光谱出现吸收谱带的位置相似,其中吸收强度最大的为形成氢键的—OH的伸缩振动,此外还有芳香性CC伸缩振动、有机羧酸盐COO-反对称伸缩振动、碳水化合物中烷氧基C—O的振动等,人工林土壤DOM中碳水化合物的比例增加是其结构简单的主要原因。土壤DOM中结构复杂、分子量大的组分不易向下迁移;天然林与人工林间土壤DOM数量及光谱学特征的差异主要与凋落物输入及营林措施的干扰有关;本研究所涉及的3种人工林中,福建柏更有利于土壤养分的累积。

UV-B辐射促进红壤水稻土中碳氮转化

以母质相同而有机质含量不同的两种水稻土(高有机质土,HO;低有机质土,LO)为对象,研究了三种强度的紫外(UV-B)辐射对两种土壤碳、氮转化的影响。结果表明:随着UV-B辐射强度的增加,土壤有机碳(TOC)含量降低,而可溶性有机碳(DOC)含量增加;UV-B辐射促进了土壤有机碳的降解和硝态氮的增加。在高强度的UV-B(2.83 W·m^(-2))辐射处理96 h后,LO和HO土壤的TOC含量分别减少了9.89%和10.16%,而DOC含量分别提高了39.24%和50.50%;同样辐射条件下,LO和HO土壤NO_3^--N含量分别比接受辐射前增加了74.48%和81.87%。因此,在农业生产中为了保护土壤碳库,减少氮素损失,应尽量避免地表裸露以降低UV-B辐射对土壤碳、氮转化的影响。

外加碳源对污水灌溉系统氮素迁移转化影响的实验研究

基于室外土柱实验装置,开展苜蓿作物生长条件下污水灌溉土地处理慢渗系统氮素迁移转化的实验研究,探讨在灌溉原污水中添加碳源对污灌系统氮素平衡和作物生长的影响,试验中考虑了不同碳氮比的影响。结果表明,随着灌溉原污水中有机碳含量的增加,苜蓿的干物质量和吸氮量逐渐减少,土壤氮素淋溶量逐渐增大,反硝化和氨挥发引起的氮素气态逸出量有所增加,氮素气态逸出和作物对氮素的吸收利用是该类污灌系统去除氮素的最主要途径。在本文特定作物和土壤条件下,增加灌溉原污水中的有机碳含量将不利于污灌系统对氮素的去除。

EA-Conflo-IRMS联机系统的燃烧转化率漂移及其对氮、碳同位素比值测定的影响

本文给出了元素分析仪-同位素比值质谱(EA-Conflo-IRMS)联机系统的燃烧转化率随测量样品次数的变化规律,以及样品的氮、碳同位素测量值与其燃烧转化率的关系。在测量前356个样品时仪器的燃烧转化率几乎不变,测量接下来的127个样品时燃烧转化率逐渐递减,而最后65个样品的燃烧转化率保持在另一个显著降低的水平。当燃烧转化率显著降低时,还原管的填料被大量氧化,氧化管上部的氧化能力下降。尽管由于受多种因素的影响同位素测定值的变化表现出一定的复杂性,但是样品的氮、碳同位素值总体上随着燃烧转化率的降低而变负。为了校正仪器漂移的状态,采用反标定方法对EA-Conflo-IRMS联机系统在状态漂移时的CO2参考气同位素值进行了重新设定,并再次测量了几个标准样的碳同位素值,其结果的准确度在0.1‰以内且测量精度好于0.15‰。可见,定期通过反标定来消除燃烧转化率漂移对同位素值产生的影响是可行的。

模型化合物吡啶加热氧化规律研究

为研究煤中吡啶型氮的氧化规律,选取吡啶为煤的含氮模型化合物,采用傅立叶红外光谱仪(Ft Ir)和烟气分析仪连用,在600～1400℃温度范围内,对其氧化产物进行研究.实验结果表明,吡啶氧化产物主要是NO、NO2、N2O、CO和CO2.N2O在750～900℃生成量最大;氧气量大于或等于理论氧气量的76%时,CO在650℃存在一个高峰,NOx随着温度升高而增加;氧气量等于理论氧气量的59%时,生成大量CO,抑制了NOx的生成.

中亚热带2种经济林土壤可溶性有机质数量与光谱学特征比较

以46年生杉木(Cunninghamia lanceolata)及锥栗(Castanea henryi)人工林为对象,研究其表层土壤(0-5cm,5-10cm)可溶性有机质(DOM)数量和光谱学特征,比较2树种差异对土壤可溶性有机质的影响。结果表明,杉木林土壤可溶性有机碳(DOC)及可溶性有机氮(DON)含量均显著高于锥栗林,其芳香化及腐殖化程度亦高于锥栗林,但荧光效率值低于锥栗林。荧光光谱图显示,杉木林土壤DOM在芳香性脂肪族及木质素类复杂结构荧光基团处的吸收大于锥栗林。傅里叶红外光谱中吸收强度最大的谱带来自于形成氢键的-OH的伸缩振动,此外还有碳水化合物中烷氧基C-O及氨基酸C-N的振动等。相关分析结果显示,土壤DOM光谱学特征值与土壤养分含量间存在一定程度的相关性。与锥栗林相比,杉木林土壤DOM含量更高,结构更复杂,更有利于土壤养分的存蓄。

生物稳定塘碳、氮、磷物质迁移转化模型的研究

本研究较系统地在试验基础上建立了生物稳定塘系统内碳、氮、磷营养物质转移规律的生态学模型,并对模型进行了全面参数估值和估值的灵敏度分析,用实地塘数据对模型进行了检验。结果表明:模型结构合理,总体上能够反映碳、氮、磷在稳定塘正常运转条件下的迁移转化规律及塘内生物和生物化学反应的特征。模型参数适用,解法成功,具有广泛的应用前景。