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1.
生物质炭对酸性菜地土壤N2O排放及相关功能基因丰度的影响 总被引:4,自引:2,他引:2
2.
农田土壤N2O排放的关键过程及影响因素 总被引:10,自引:3,他引:7
一氧化二氮 (N2O) 作为重要的温室气体之一,在全球气候变化研究中引人关注。随着氮肥使用量的增加,农田土壤N2O排放已经成为全球关注和研究的热点。人们普遍认为土壤硝化、反硝化过程是N2O产生的两个主导途径,而诸如施肥、灌水等农田管理措施以及土壤pH、温度等环境因子均会影响农田土壤N2O产生和排放。本文系统论述了土壤N2O产生的各主要途径,并综述了氮源、碳源、水分含量、氧气含量、土壤pH和温度以及其他调控因子对N2O排放的影响,旨在阐明各过程对N2O排放的产生机制及主要环境因子的影响,以期为后续研究提供参考和理论依据。农田土壤硝化过程本身对N2O排放的直接贡献较小,N2O产生的主要来源是包含硝化细菌的反硝化、硝化–反硝化耦合作用在内的生物反硝化过程。真菌反硝化和化学反硝化在酸性土壤以及硝酸异化还原成铵过程在高有机质和厌氧土壤环境中对N2O排放具有重要作用。未来研究可从农田土壤N2O的产生和消耗机制、降低N2O/N2产物比、N2O的还原过程及相关影响因素进行深入研究。此外,利用新技术方法,探究土壤物理、化学和生物学因素对氮素转化过程的影响,重点关注N2O峰值排放及相关联微生物的响应,并构建土壤氮素平衡和N2O排放模型,可进一步加深对农田土壤N2O排放机制和影响因素的理解。 相似文献
3.
【目的】施用硝化抑制剂是削减农田N2O排放的有效措施,本文研究不同种类硝化抑制剂对土壤N2O排放的影响,为选择高效硝化抑制剂以实现黑土N2O减排提供科学依据。【方法】在黑龙江省东部典型旱作黑土区进行田间试验。设置6个处理:不施氮肥(N0),常规施氮(N200),减氮20%(N160),减氮20%分别配施硝化抑制剂双氰胺(N160+DCD)、3,4-二甲基吡唑磷酸盐(N160+DMPP)和2-氯-6 (三氯甲基)-吡啶(N160+CP)。测定全年土壤N2O排放通量,同步测定土壤温度和含水量以及玉米生长季土壤铵态氮(NH4+-N)、硝态氮(NO3--N)和可溶性有机碳(DOC)含量。【结果】施氮显著提高了土壤NH4+-N含量,且各施氮处理间差异不显著。施用硝化抑制剂处理降低了土壤NO3--N含量,DCD和DMPP处理的NO3--N... 相似文献
4.
硝化抑制剂对稻田土壤N2O排放和硝化、反硝化菌数量的影响 总被引:1,自引:0,他引:1
5.
为揭示不同生物硝化抑制剂(BNIs)对红壤性水稻土N2O排放的影响差异及作用机制,通过21 d的土柱淹水培养试验,比较了三种BNIs 1,9-癸二醇(1,9-D)、亚麻酸(LN)和3-(4-羟基苯基)丙酸甲酯(MHPP)与化学合成硝化抑制剂双氰胺(DCD)对土壤N2O排放及相关硝化、反硝化功能基因的影响。结果表明:不同BNIs(1,9-D、LN、MHPP)可以显著平均降低土壤N2O日排放峰值40.1%;1,9-D和MHPP可分别抑制N2O排放总量44.5%和43.9%,而DCD和LN对N2O排放总量没有显著影响。1,9-D和MHPP对AOA(氨氧化古菌)、AOB(氨氧化细菌)硝化菌和nirS、nirK型反硝化菌的调控均有所不同,1,9-D可以同时抑制AOA、AOB和nirS微生物的生长;MHPP仅可以抑制AOA的生长;其中,AOA-amoA和nirS基因丰度与土壤N2O的排放呈显著正相关关系。同时,1,9-D和MHPP均增加了nosZ基因丰度及其与AOA-... 相似文献
6.
甲烷氧化微生物和氨氧化微生物均是既可以氧化甲烷(CH4)又可以氧化氨(NH3),氨氧化是硝化作用的限速步骤,也是好氧土壤氧化亚氮(N2O)排放的主要生物路径。选取内蒙古草原围封禁牧土壤为研究对象,利用稳定同位素核酸探针技术(DNA-SIP)探讨不同氮水平下土壤活性甲烷氧化微生物与硝化微生物及其相互作用机制。结果发现低氮添加促进甲烷氧化活性,而高氮添加抑制甲烷氧化活性;低氮和高氮添加均显著增强硝化活性。基于DNA-SIP的高通量测序结果发现Methylobacter MOB和Nitrosospira AOB/Nitrospira NOB分别是该土壤的主要活性甲烷氧化和硝化微生物。网络结构分析发现Methylobacter MOB和Nitrosospira AOB/Nitrospira NOB存在显著负相关关系,进一步证明活性甲烷氧化和硝化微生物之间存在竞争性相互作用。以上结果表明,氮素水平影响草原土壤甲烷氧化和硝化微生物的相互作用,研究结果为采取措施调控草原土壤CH4的汇和N2O... 相似文献
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8.
土壤反硝化作用是土壤N2O产生的重要过程,亚硝酸盐还原酶(NIR)催化的亚硝态氮(NO-2)还原为一氧化氮(NO)是反硝化作用的关键环节,研究长期施肥对反硝化微生物的影响及其与N2O排放的关系对于全面理解土壤反硝化过程具有重要意义。基于28年的旱作雨养长期施肥试验,通过常规监测、定量PCR和高通量测序等探讨了长期不同施肥(不施肥CK、偏施肥的单施氮肥N和氮钾配施NK、以及氮磷钾平衡施肥NPK)下土N2O排放和nirS反硝化细菌群落特征及两者之间的关系。结果表明:长期化肥施用(N,NK和NPK)均显著提高了N2O累积排放量,其中平衡施肥(NPK)最高。长期化肥施用对nirS基因丰度和nirS型反硝化细菌的α-多样性无显著影响,但长期平衡施用化肥提高了uncultured_bacterium_2303和Rhodanobacter_sp._D206a的相对丰度,降低了unclassified_k_norank_d_Bacteria和unclassified_p_Proteobacteria的相对丰度,从而改变了nirS型反硝化细菌的群落结构组成。雨养旱作条件下,土壤有机碳(SOC)、全氮(TN)、有效磷(AP)和pH等土壤性质是土nirS型反硝化细菌群落结构组成变化的主要影响因素。土nirS型反硝化细菌群落结构组成对土壤N2O排放具有显著影响,而nirS基因丰度和nirS型反硝化细菌多样性并没有显著影响。 相似文献
9.
有机和无机肥配比对黄褐土硝化和反硝化微生物丰度及功能的影响 总被引:5,自引:1,他引:4
10.
土壤氮气排放研究进展 总被引:3,自引:0,他引:3
自20世纪初人类发明并掌握工业合成氨的技术以来,氮肥施用量迅速增长。在一部分国家或地区,氮肥的施入量已经超过作物对氮素的需求,导致大量氮素损失到环境中,造成氨挥发、氧化亚氮排放、地下水硝酸盐污染等环境问题。土壤在微生物的作用下可以通过反硝化、厌氧氨氧化等过程将活性氮素转化为惰性氮气,达到清除过多活性氮的目的。由于大气中氮气背景浓度太高,因此很难直接准确测定土壤的氮气排放速率,导致土壤氮气排放通量、过程与调控机制研究远远落后于土壤氮循环的其他方面。本文综述了土壤氮气排放主要途径(反硝化、厌氧氨氧化与共反硝化)及其对土壤氮气排放的贡献;测定土壤氮气排放速率的方法(乙炔抑制法、氮同位素示踪法、N2/Ar比率-膜进样质谱法、氦环境法与N2O同位素自然丰度法)及其优缺点;调控土壤氮气排放通量的主要因素(氧气、可溶性有机碳、硝酸盐、微生物群落结构与功能基因表达等)及其相关作用机制。最后指出研发新的测定原位无扰动土壤氮气通量的方法是推进本领域相关研究的关键;定量典型生态系统(如旱地农田、稻田、森林、草地与湿地)土壤氮气排放通量,阐明其中的微生物学机制,模拟并预测土壤氮气排放对全球变化的响应规律是本领域的研究热点与发展方向。 相似文献
11.
Soils are the major source of the greenhouse gas nitrous oxide (N2O) to our atmosphere. A thorough understanding of terrestrial N2O production is therefore essential. N2O can be produced by nitrifiers, denitrifiers, and by nitrifiers paradoxically denitrifying. The latter pathway, though well-known in pure culture, has only recently been demonstrated in soils. Moreover, nitrifier denitrification appeared to be much less important than classical nitrate-driven denitrification. Here we studied a poor sandy soil, and show that when moisture conditions are sub-optimal for denitrification, nitrifier denitrification can be a major contributor to N2O emission from this soil. We conclude that the relative importance of classical and nitrifier denitrification in N2O emitted from soil is a function of the soil moisture content, and likely of other environmental conditions as well. Accordingly, we suggest that nitrifier denitrification should be routinely considered as a major source of N2O from soil. 相似文献
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《Soil biology & biochemistry》2001,33(12-13):1723-1732
Nitrifier denitrification is the pathway of nitrification in which ammonia (NH3) is oxidized to nitrite (NO2−) followed by the reduction of NO2− to nitric oxide (NO), nitrous oxide (N2O) and molecular nitrogen (N2). The transformations are carried out by autotrophic nitrifiers. Thus, nitrifier denitrification differs from coupled nitrification–denitrification, where denitrifiers reduce NO2− or nitrate (NO3−) that was produced by nitrifiers. Nitrifier denitrification contributes to the development of the greenhouse gas N2O and also causes losses of fertilizer nitrogen in agricultural soils. In this review article, present knowledge about nitrifier denitrification is summarized in order to give an exact definition, to spread awareness of its pathway and controlling factors and to identify areas of research needed to improve global N2O budgets. Due to experimental difficulties and a lack of awareness of nitrifier denitrification, not much is known about this mechanism of N2O production. The few measurements carried out so far attribute up to 30% of the total N2O production to nitrifier denitrification. Low oxygen conditions coupled with low organic carbon contents of soils favour this pathway as might low pH. As nitrifier denitrification can lead to substantial N2O emissions, there is a need to quantify this pathway in different soils under different conditions. New insights attained through quantification experiments should be used in the improvement of computer models to define sets of conditions that show where and when nitrifier denitrification is a significant source of N2O. This may subsequently render the development of guidelines for low-emission farming practices necessary. 相似文献
13.
《Communications in Soil Science and Plant Analysis》2012,43(19):2264-2278
To understand the contribution of key microbial processes to nitrous oxide (N2O) emission in intensively cultivated black soil, laboratory incubation were conducted at 70% water-holding capacity (WHC) and 25 °C, using different gases (air, oxygen, or argon) within the headspace of the incubation chambers to evaluate gas inhibition effects. Arable black soil was sampled from an experimental field that has received urea since October 1979. Nitrification contributed to 57% of total N2O emission, of which as much as 67% resulted from heterotrophic nitrification. These data strongly suggest that high soil organic carbon concentrations and low pH values are more favorable to N2O production through heterotrophic, rather than autotrophic, nitrification. Nitrous oxide produced by denitrification accounted for 28% of the total N2O emission, and the nitrifier denitrification accounted for 15% of the N2O emitted from the tested soil. These findings indicate that heterotrophic nitrification was the primary N2O production process in the tested soil. 相似文献
14.
森林土壤氧化亚氮排放对大气氮沉降增加的响应研究进展 总被引:1,自引:1,他引:1
森林土壤N2O来源于土壤氮素的氧化还原反应,硝化、反硝化、硝化细菌反硝化以及化学反硝化是其产生的四个关键过程。当前,氮素富集条件下森林土壤N2O排放存在硝化和反硝化主导作用之争,对大气氮沉降增加的响应模式以及微生物驱动机制尚不清楚。综述了森林土壤N2O来源的稳定性同位素拆分,森林土壤总氮转化和N2O排放对增氮的响应规律,增氮对N2O产生菌群落活性和组成的影响,并指出研究的薄弱环节与未来的研究重点。总体而言,森林土壤N2O排放对大气氮沉降增加的响应呈现非线性,包括初期无明显响应、中期缓慢增加和后期急剧增加三个阶段,取决于森林生态系统"氮饱和"程度。施氮会引起森林土壤有效氮由贫氮向富氮的转变,相应地改变了土壤硝化细菌和反硝化细菌群落丰度与组成,进而影响土壤N2O排放。由于森林土壤N2O排放监测、土壤总氮转化和N2O产生菌群落动态研究多为独立进行的,难以阐明微生物功能群与N2O排放之间的耦合关系。未来研究应该有机结合15N-18O标记和分子生物学技术,准确量化森林土壤N2O的来源,揭示森林土壤N2O排放对增氮的非线性响应机理。 相似文献
15.
Summary A sandy soil amended with different forms and amounts of fertilizer nitrogen (urea, ammonium sulphate and potassium nitrate) was investigated in model experiments for N2O emission, which may be evolved during both oxidation of ammonia to nitrate and anaerobic respiration of nitrate. Since C2H2 inhibits both nitrification and the reduction of N2O to N2 during denitrification, the amount of N2O evolved in the presence and absence of C2H2 represents the nitrogen released through nitrification and denitrification.Results show that amounts of N2O-N lost from soils incubated anaerobically with 0.1% C2H2 and treated with potassium nitrate (23.1 µg N-NO
3
–
/g dry soil) exceeded those from soils incubated in the presence of 20% oxygen and treated with even larger amounts of nitrogen as urea and ammonium sulphate. This indicates that nitrogen losses by denitrification may potentially be higher than those occurring through nitrification. 相似文献
16.
Kentaro Hayashi Takeshi Tokida Masako Kajiura Yosuke Yanai Midori Yano 《Soil Science and Plant Nutrition》2013,59(1):2-33
Croplands are an important source of atmospheric methane (CH4) and nitrous oxide (N2O), both potent greenhouse gases. Reduction of cropland CH4 and N2O emissions is expected to mitigate climate change. However, large uncertainty remains in the assessment and prediction of these emissions, which prevents us from establishing appropriate mitigation options and strategies. The uncertainty is attributed mainly to the high spatiotemporal variability in emissions (e.g., emission spikes of N2O). Understanding and quantifying how hotspots of CH4 and N2O production in soil and then hot moments of their emissions occur would help reduce the uncertainty. This review focuses on soil–plant systems, particularly the rhizosphere, as possible hotspots of production and consumption of CH4 and N2O. It is well known that the rhizosphere controls CH4 emission strongly, though each process of production and consumption remains to be quantified. On the other hand, surprisingly little attention has been paid to N2O, besides the fact that plant roots strongly control nitrification and denitrification. We review the current knowledge of cropland CH4 and N2O emissions, and conclude that soil–plant interactions strongly affect cropland emissions of both gases, in which functions of plant roots affecting biogeochemical factors (e.g., availability of oxygen, labile organic carbon and inorganic nitrogen) in the rhizosphere and phenological changes are particularly important. In relation to the status of current knowledge, we discuss future research needed. 相似文献
17.
《Soil Science and Plant Nutrition》2013,59(7):967-972
We studied the effect of repeated application (once every 2 d) of a fertilizer solution with different ratios of NH4 + - and NO3 ?-N on N2O emission from soil. After the excess fertilizer solution was drained from soil, the water content of soil was adjusted to 50% of the maximum water-holding capacity by suction at 6 × 103 Pa. Repeated application of NH4 +- rich fertilizer solution stimulated nitrification in soil more than NO3 ?-rich fertilizer. Although the evolution of N2O through nitrifier denitrification tended to increase with the repeated addition of a fertilizer solution rich in NH4 + rather than in NO3 ?, the contribution of nitrifier denitrification remained at levels of 20 to 36% of the total emission regardless of the inorganic N composition. The total emission of N2O also tended to increase with the application of NH4 +- rather than NO3 ?-rich fertilizer. It was suggested that the coupled process of nitrification and denitrification at micro-aerobic sites became important when fertilizer rich in NH4 + was applied to soil under relatively aerobic conditions. 相似文献
18.
硝化反应是土壤、特别是干旱半干旱地区农业土壤N2O产生的重要途径之一。但是,目前环境条件对硝化反应中N2O排放的影响研究较少,而在国内外通用的几个模型中均用固定比例估算硝化反应过程中N2O的排放。本文通过砂壤土培养试验,研究了土壤温度、水分和NH4+-N浓度对硝化反应速度及硝化反应中N2O排放的影响,并用数学模型定量表示了各因素对硝化反应的作用,用最小二乘法最优拟合求得该土壤的最大硝化反应速度及N2O最大排放比例。结果表明,随着温度升高,硝化反应速度呈指数增长;水分含量由20%充水孔隙度(WFPS)增加到40%WFPS时,反应速度增加,水分含量增加到60%WFPS时反应速度略有降低;NH4+-N浓度增加对硝化反应速度起抑制作用。用米氏方程描述该土壤的硝化反应过程,其最大硝化反应速度为6.67mg·kg?1·d?1。硝化反应中N2O排放比例随温度升高而降低;随NH4+-N浓度增加而略有增加;20%和40%WFPS水分含量时,硝化反应中N2O排放比例为0.43%~1.50%,最小二乘法求得的最大比例为3.03%,60%WFPS时可能由于反硝化作用,N2O排放比例急剧增加,还需进一步研究水分对硝化反应中N2O排放的影响。 相似文献
19.
施肥对夏玉米季紫色土N2O排放及反硝化作用的影响 总被引:9,自引:0,他引:9
采用原状土柱-乙炔抑制培养法研究了施肥对紫色土玉米生长季土壤N2O排放通量和反硝化作用的影响.结果表明:玉米季施肥显著增加土壤N2O排放和反硝化损失,同时,各施肥处理间N2O排放与反硝化损失量差异显著.猪厩肥、猪厩肥配施氮磷钾肥、氮肥、氮磷钾肥和秸秆配施氮磷钾肥等处理的土壤N,O排放量分别为3.01、2.86、2.51、2.19和1.88 kg hm-2,分别占当季氮肥施用量的1.63%、1.53%、1.30%、1.09%和0.88%,反硝化损失量分别为6.74、6.11、5.23、4.69和4.12 kg hm-2,分别占当季氮肥施用量的3.97%、3.55%、2.97%、2.61%和2.23%,不施肥土壤的N2O排放量和反硝化损失量仅为0.56和0.78 kg hm-2.施肥是紫色土玉米生长前期(2周内)土壤N2O排放和反硝化速率出现高峰的主要驱动因子,土壤铵态氮和硝态氮含量是影响土壤N2O排放、土壤硝化和反硝化作用的限制因子,土壤含水量是重要影响因子,降雨是主要促发因素.土壤N2O排放量与反硝化损失量的比值介于0.45 ~0.72之间,土壤反硝化损失量极显著高于土壤N2O排放量,说明土壤反硝化作用是紫色土玉米生长季氮肥损失的重要途径. 相似文献
20.
冻融对土壤氮素转化和N2O排放的影响研究进展 总被引:4,自引:0,他引:4
在中、高纬度及高海拔地区,土壤冻融现象常有发生。冻融作用通过影响土壤理化性质和生物学性状进而影响土壤氮素转化过程及N2O的产生和释放,但迄今关于冻融对土壤氮素转化过程影响的研究结果还不尽一致,正效应或负效应均存在,土壤冻融期间N2O排放对全年N2O排放总量的贡献程度也存在着较大差异。本文重点论述了土壤冻结或冻融循环过程对土壤氮矿化、固持、硝化和反硝化等主要氮素转化过程的影响机制,同时分析了可引起冻融期间N2O排放强度变化的四种可能机理(禁锢-释放、环境-底物诱导、N2O还原酶抑制和化学反硝化增强)。指出在全球变暖背景下研究土壤冻融格局改变影响土壤氮素转化过程及N2O排放的必要性,并简要提出了若干理论问题及研究方向。 相似文献