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硝化反硝化细菌菌落与N_2O排放关系研究 总被引：1，自引：0，他引：1
虽然硝化反硝化细菌菌落组成成分与从土壤中排放出来的N2O之间的关联尚不清楚,但是,硝化反硝化细菌的菌落组成、数量与N2O的排放活动已在两个常见的耕地型湿地(CW)与非耕地型湿地(UW)上做过探讨。本研究的假设有:1)不同的硝化反硝化菌落选择不同的地形;2)反硝化是产生N2O的主要步骤;3)在硝化反硝化细菌菌群组成、数量与N2O排放之间是有某种联系的。选在圣丹尼斯国家野生动物保护区(SDNWA)的3块CW与3块UW上进行比较试验。结果表明:1)硝化作用是N2O排放的根本来源;2)耕作土壤增加了硝化细菌的产量,同时消减了硝化细菌的数量;3)反硝化细菌的数量没有因为耕作活动而增加;4)在土地利用和地形为变量的前提下,硝化细菌、反硝化细菌菌落组成和数量与N2O的排放是没有关联的。 相似文献
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森林土壤是大气N_2O重要的排放源。施肥、采伐、火烧、林下植被管理等营林措施和土地利用变化改变了土壤理化性质和土壤微气候,显著影响森林土壤N_2O的产生与排放。综述了森林土壤N_2O排放对不同营林措施的响应,探讨了营林措施影响土壤N_2O排放的主要机理,并提出目前研究的不足和未来研究的重点。总体而言,森林转变为农田、草地后增加了土壤N_2O排放,而农田和草地恢复成人工林后减弱了土壤N_2O排放;天然林转换为人工林或次生林后土壤N_2O排放没有明确结论;森林生态系统"氮饱和"程度使得森林土壤N_2O排放对施肥呈非线性响应,即初期无明显响应、中期缓慢增加和后期急剧增加;火烧一般增加土壤N_2O排放;采伐改变土壤温度、含水量、有机碳的分解和利用等,从而增强森林土壤N_2O排放能力;剔除林下植被提高土壤温度,加快了表层土壤有机碳的分解矿化,促进土壤N_2O排放;种植固氮植物增加了土壤有机碳和土壤氮含量,土壤N_2O排放增强。今后的研究应更多地关注多种因素和气候变化对林地土壤N_2O排放影响的内在机理以及氨氧化细菌、硝化细菌和反硝化细菌等微生物对各种干扰因素的响应机制。 相似文献
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转基因水稻秸秆还田对土壤硝化反硝化微生物群落的影响 总被引：2，自引：0，他引：2
转基因作物可能通过根系分泌物和植株残体组成的改变及外源基因的转移释放令土壤微生物群落产生变化,影响土壤微生物的生态功能。氨氧化细菌和反硝化细菌是驱动土壤硝化和反硝化过程的关键微生物,其群落结构的变化直接关系土壤氮素的转化与利用。本研究利用荧光定量PCR和PCR-DGGE技术分析了转cry1Ac/cpti双价抗虫基因水稻‘Kf8’秸秆还田降解过程中,土壤氨氧化细菌和反硝化细菌群落丰度与组成的变化,探讨转基因水稻是否存在影响稻田土壤氮素转化与N2O排放的可能。结果显示:无论是氨氧化细菌amo A基因还是反硝化细菌nirS基因,其丰度在转基因水稻‘Kf8’与非转基因水稻‘Mh86’的秸秆还田土壤中都没有显著差异;转基因水稻‘Kf8’和非转基因水稻‘Mh86’秸秆还田降解过程中0~10 cm土层中的amo A基因丰度均显著高于10~20 cm及20~30 cm土层(P0.05);各深度土层中的nirS基因丰度均存在随秸秆还田时间延长而增加的趋势。水稻秸秆还田降解过程中,转基因水稻‘Kf8’的土壤氨氧化细菌和反硝化细菌的群落多样性指数及组成,均与非转基因水稻‘Mh86’没有显著差异。相关分析结果表明土壤氨氧化细菌和反硝化细菌群落组成均与水稻秸秆还田时间存在显著相关性(P=0.002),反硝化细菌群落组成还与土层深度显著相关(P=0.024)。本研究表明转cry1Ac/cpti抗虫基因水稻秸秆还田对稻田土壤硝化和反硝化关键微生物群落不会产生明显影响。就土壤微生物群落而言,转cry1Ac/cpti抗虫基因水稻秸秆还田不存在影响土壤氮素转化与N2O排放的可能。 相似文献
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农田土壤硝化反硝化作用及其对生物炭添加响应的研究进展 总被引：1，自引：0，他引：1
氧化亚氮（N2O）是重要的温室气体之一,还会破坏大气臭氧层,影响全球气候变化。农田土壤是N2O最主要的排放源,由微生物主导的硝化和反硝化作用是其最主要的排放途径,因此,土壤的硝化和反硝化作用备受关注。在综合国内外相关研究的基础上,就区分硝化和反硝化作用对N2O排放贡献的研究方法、土壤N2O产生途径及其影响因素以及施用生物炭对N2O排放的影响机理进行归纳总结。结果表明：硝化和反硝化作用对生物炭的响应不同,在N2O减排效应上也存在很大的不确定性,其内在机理尚不明确。在此基础上,提出区分硝化和反硝化作用对N2O排放贡献的最佳研究方法,并就农田土壤硝化反硝化作用的影响因素以及对生物炭的响应机制进行研究展望。 相似文献
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农田土壤硝化—反硝化作用与N2O的排放 总被引：8，自引：0，他引：8
在北京潮土上研究了冬小麦夏玉米轮作体系下土壤硝化反硝化作用以及N2O排放情况。结果表明，小麦生育期土壤温度及含水量降低，无论是反硝化损失氮量还是土壤的N2O生成排放量均不高。土壤的N2O生成排放量与反硝化氮量相当或低于反硝化氮量。玉米生育期土壤温度升高以及孔隙含水量的较大的改善，反硝化损失氮量、N2O生成排放量有明显上升。通常情况下土壤反硝损失氮量与N2O排放氮量基本处于同一水平。在玉米十叶期追肥后的较短时间内，N2O总排放量明显高于反硝化损失氮量，说明至少在这一阶段中，硝化作用在北方旱地土壤N2O的排放中发挥了主要作用。在评价北方旱地农田土壤氮素硝化反硝化损失中，硝化作用的氮素损失是不可忽视的重要方面。 相似文献
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大气中氧化亚氮（N2O）浓度的上升加剧了全球变暖。森林土壤在调节大气N2O浓度中发挥着至关重要的作用。近年来,氮（N）输入对森林土壤N2O通量的影响备受关注。然而,森林土壤N2O排放对N输入响应的机制,尤其是植物和微生物对N2O通量的调控作用尚缺乏系统研究。因此,本文综述了N输入如何通过森林植被（根系N吸收、凋落物分解和形成丛枝菌根）和土壤微生物（微生物量和群落组成）调控N2O产生途径从而影响森林土壤N2O排放。结果表明,植物的竞争性氮吸收能降低氮输入对N2O排放的促进作用,其作用大小可能主要取决于土壤“氮饱和”状态。植物凋落物主要通过分解过程中的养分归还和次生代谢产物释放来影响氮输入背景下的森林土壤N2O排放,前者具有促进作用,而后者具有抑制作用。丛枝菌根主要通过吸收有效氮和水分、促进团聚体形成以及改变N2O相关功能基因群落调控森林土壤N2O通量。N输入导致的土壤酸化或养分限制,通常会降低微生物量和/或改变微生物群落组成,从而控制N2O排放。N输入对N2O不同产生途径也会造成影响,受土壤湿度、N2O底物浓度以及N2O相关功能基因丰度（AOB、 AOA、nirK、 nirS和nosZ）的调控。未来在模型预测中,需要将植物氮吸收、凋落物分解、菌根以及N2O产生途径充分纳入模型,以提高模型预测准确性,为全球变化背景下制订森林管理政策和温室气体减排措施提供支持。 相似文献
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为探明地下滴灌对土壤 N2O 排放的影响及机理,本文研究了不同滴灌管埋深(0、10、20、30 cm,即CK、 S10、 S20、 S30)番茄根区土壤N2O排放规律,分析了地下滴灌形成的根区土壤水热、养分、微生物等微域环境对 N2O 排放的影响。结果表明土壤供水位置(滴灌管埋深)不同,显著影响土壤水分分布及其他土壤微域环境因素,其中根系分叉数、0-20 cm土壤孔隙度、反硝化细菌、亚硝化细菌等是影响N2O累积排放量的主要因素。S10 番茄根系分叉数为 CK 的1.85倍；0-20 cm土壤孔隙度比 CK 显著增加 10.72%；土壤硝态氮为CK的2.02倍,土壤溶解性有机碳 为CK的1.49倍；果实成熟期土壤亚硝化菌数量为 CK 的 2.11 倍；开花坐果期、果实成熟期土壤反硝化菌数量为 CK 的 3.8、3.75 倍；土壤N2O累积排放量为CK的1.99倍。S20 番茄根系分叉数为 CK 的2.77倍；0-20 cm土壤孔隙度比 CK 显著增加22.32%；土壤硝态氮分别为CK的2.66倍,土壤溶解性有机碳为 CK的1.38倍；果实成熟期土壤亚硝化菌数量为 CK 的 5.56 倍；开花坐果期、果实成熟期土壤反硝化菌数量为 CK 的 6.0、12.5 倍；土壤N2O累积排放量为CK的2.24倍。S30 番茄根系分叉数为 CK 的2.22倍；土壤硝态氮为CK的1.66倍；开花坐果期亚硝化细菌数量、反硝化细菌分别为CK 的 2.0、1.8倍；但反硝化细菌数量、硝态氮和溶解性有机碳含量、0-20 cm土壤孔隙度等显著低于S20处理,根系-土壤交互作用减弱,土壤N2O累积排放量与CK无显著差异。总体上,滴灌管埋深10 cm、20 cm 提高了土壤N2O累积排放量,但其排放显著低于IPCC推荐的排放标准且能提高番茄植株根、茎氮含量,在生产实际中优于常规地表覆膜滴灌。 相似文献
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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
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Subtropical forests in SW China, receiving high nitrogen (N) deposition, have been reported to show high N retention. N removal by denitrification may be one important process favored by warm and wet soils during monsoonal summer when most of the atmogenic N input occurs. Due to low pH soils which are common in this region, N removal by denitrification may entail substantial N2O emissions. In this study, we explored intrinsic denitrification characteristics of soils from different landscape elements of a forested headwater catchment in SW China (Tieshanping, Chongqing). Laboratory incubations were used to measure instantaneous denitrification rates, apparent specific denitrifier growth rates, denitrification product stoichiometries (N2O/(N2O + N2)) and response to carbon-addition as a function of soil depth and landscape position. The results revealed that potential denitrification and denitrifier growth rates were highest in top soils along a hill slope, and decreased strongly with soil depth due to C-limitation. A hydrologically connected, colluvial groundwater discharge zone showed equally high instantaneous denitrification rates which were more equally distributed with depth. Denitrifying communities in the top horizons of the hill slope were less efficient in expressing N2O reductase in response to anoxia resulting in higher N2O/(N2 + N2O) product ratios than found in soils of the groundwater discharge zone, suggesting that a significant share of the deposited N can be lost as N2O from the hill slopes. Differences in denitrification traits appeared to be linked to eco-hydrological conditions in the two landscape elements and to substrate availability along the hydrological flowpath. Our study supports the notion that denitrification plays an important role for observed N removal in SW Chinese forest ecosystems and illustrates how habitat functions constrain the amount of N2O emitted during N removal. 相似文献
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氮肥水平对稻田细菌群落及N2O排放的影响 总被引：3，自引：0，他引：3
作为土壤氮素转化的驱动者,微生物群落结构关系着稻田氮素利用及温室气体N_2O排放等问题。本研究分别基于高通量测序和荧光定量PCR技术,分析了不同氮肥水平[CK(不施氮)、N(施N 180 kg·hm-2)、2/3N(施N 120 kg·hm-2)、1/3N(施N 60 kg·hm-2)]下稻田细菌群落及硝化反硝化关键微生物功能基因丰度的变化。结果显示:氮肥水平提高增加了稻田细菌物种丰富度Chao1指数和群落多样性Shannon指数,改变了细菌群落组成,其中与硝化作用相关的硝化螺菌门Nitrospirae和嗜酸的醋杆菌门Acidobacteria的相对丰度随氮肥水平提高而增加,但甲烷氧化菌Methylosinus的相对丰度随氮肥水平提高而降低。氮肥水平对稻田硝化作用关键微生物氨氧化细菌amo A基因丰度的影响较大,0~5 cm和10~20 cm深度土层中的amo A基因丰度均随氮肥用量增加而提高;反硝化作用关键微生物功能基因nir S、qno B和nos Z的丰度在不施肥处理(CK)中显著低于施肥处理(1/3N、2/3N和N)(P0.05),但1/3N、2/3N和N处理的稻田nir S基因丰度没有明显差异;0~5 cm土层中qno B和nos Z基因丰度存在随氮肥水平提高而增加的趋势,10~20 cm土层中nos Z基因丰度在2/3N和N处理下显著高于1/3N处理(P0.05)。N处理的稻田N_2O排放通量显著高于2/3N及1/3N处理(P0.05),后者又显著高于CK处理(P0.05)。相关分析结果表明稻田N_2O排放通量与0~5 cm土层中硝化螺菌门Nitrospirae相对丰度及10~20 cm土层中amo A基因丰度存在显著相关性(P0.05,n=10)。综上所述,氮肥水平提高增加了稻田细菌群落多样性,促进了稻田N_2O排放,且本研究稻田中硝化作用微生物群落及丰度变化与稻田N_2O排放的关系更为密切。 相似文献
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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
15.
为揭示亚热带森林土壤N2O排放对林分类型和氮添加的响应特征,选取位于福建省三明市的中亚热带米槠次生林、杉木人工林和马尾松人工林土壤为研究对象,分别设置无氮添加(N0 mg/kg)、低氮添加(N10 mg/kg)、中氮添加(N25 mg/kg)和高氮添加(N50 mg/kg)4个氮添加水平,进行微宇宙培养试验,测定土壤N2O排放。结果表明：与无氮添加处理相比,氮添加整体上降低3种林分土壤pH,增加土壤NH4+-N和NO3--N含量。无氮添加处理中杉木人工林和马尾松人工林土壤N2O累积排放量分别为9.67和9.62 mg/kg,显著高于米槠次生林土壤N2O累积排放量6.81 mg/kg。低氮添加处理中杉木人工林和马尾松人工林土壤N2O累积排放量显著高于米槠次生林。但在中氮和高氮添加处理中,3种林分土壤N2O累积排放量均无显著性差异。不同氮添加处理均促进3种林分土壤N 相似文献
16.
Xi-En Long Ju-Pei Shen Jun-Tao Wang Li-Mei Zhang Hongjie Di Ji-Zheng He 《Journal of Soils and Sediments》2017,17(2):384-392
Purpose
Nitrification and denitrification processes dominate nitrous oxide (N2O) emission in grassland ecosystems, but their relative contribution as well as the abiotic factors are still not well understood.Materials and methods
Two grassland soils from Duolun in Inner Mongolia, China, and Canterbury in New Zealand were used to quantitatively compare N2O production and the abundance of bacterial and archaeal amoA, denitrifying nirK and nirS genes in response to N additions (0 and 100 μg NH4 +–N g?1 dry soil) and two soil moisture levels (40 and 80 % water holding capacity) using microcosms.Results and discussion
Soil moisture rather than N availability significantly increased the nitrification rate in the Duolun soil but not in the Canterbury soil. Moreover, N addition promoted denitrification enzyme activities in the Canterbury soil but not in the Duolun soil. The abundance of bacterial and archaeal amoA genes significantly increased as soil moisture increased in the Duolun soil, whereas in the Canterbury soil, only the abundance of bacterial amoA gene increased. The increase in N2O flux induced by N addition was significantly greater in the Duolun soil than in the Canterbury soil, suggesting that nitrification may have a dominant role in N2O emission for the Duolun soil, while denitrification for the Canterbury soil.Conclusions
Microbial processes controlling N2O emission differed in grassland soils, thus providing important baseline data in terms of global change.17.
S. Castaldi 《Biology and Fertility of Soils》2000,32(1):67-72
The experiment, carried out on a forest and arable light-textured soil, was designed to study the temperature response of
autotrophic and heterotrophic N2O production and investigate how the N2O flux relates to soil respiration and O2 consumption. Although N2O production seemed to be stimulated by a temperature increase in both soils, the relationship between production rate and
temperature was different in the two soils. This seemed to depend on the different contribution of nitrification and denitrification
to the overall N2O flux. In the forest soil, almost all N2O was derived from nitrification, and its production rate rose linearly from 2 °C to 40 °C. A stronger effect of temperature
on N2O production was observed in the arable soil, apparently as a result of an incremental contribution of denitrification to
the overall N2O flux with rising temperature. The soil respiration rate increased exponentially with temperature and was significantly correlated
with N2O production. O2 consumption stimulated denitrification in both soils. In the arable soil, N2O and N2 production increased exponentially with decreasing O2 concentration, though N2O was the main gas produced at any temperature. In the forest soil, only the N2 flux was related exponentially to O2 consumption and it outweighed the rate of N2O production only at >34 °C. Thus, it appears that in the forest soil, where nitrification was the main source of N2O, temperature affected the N2O flux less dramatically than in the arable soil, where a temperature increase strongly stimulated N2O production by enhancing favourable conditions for denitrification.
Received: 26 August 1998 相似文献
18.
Yi Cheng Jing Wang Shen-Qiang Wang Jin-Bo Zhang Zu-Cong Cai 《Biology and Fertility of Soils》2014,50(7):1099-1108
Soil moisture changes, arising from seasonal variation or from global climate changes, could influence soil nitrogen (N) transformation rates and N availability in unfertilized subtropical forests. A 15?N dilution study was carried out to investigate the effects of soil moisture change (30–90 % water-holding capacity (WHC)) on potential gross N transformation rates and N2O and NO emissions in two contrasting (broad-leaved vs. coniferous) subtropical forest soils. Gross N mineralization rates were more sensitive to soil moisture change than gross NH4 + immobilization rates for both forest soils. Gross nitrification rates gradually increased with increasing soil moisture in both forest soils. Thus, enhanced N availability at higher soil moisture values was attributed to increasing gross N mineralization and nitrification rates over the immobilization rate. The natural N enrichment in humid subtropical forest soils may partially be due to fast N mineralization and nitrification under relatively higher soil moisture. In broad-leaved forest soil, the high N2O and NO emissions occurred at 30 % WHC, while the reverse was true in coniferous forest soil. Therefore, we propose that there are different mechanisms regulating N2O and NO emissions between broad-leaved and coniferous forest soils. In coniferous forest soil, nitrification may be the primary process responsible for N2O and NO emissions, while in broad-leaved forest soil, N2O and NO emissions may originate from the denitrification process. 相似文献
19.
A. V. Mamai A. L. Stepanov N. G. Fedorets 《Moscow University Soil Science Bulletin》2013,68(4):174-179
The intensity of mineralization, nitrogen fixation, and denitrification in forest soils of the Karelian middle taiga ecosystems has been evaluated. Podzol-gleyish soil underlying a birch forest with gramineous plants and miscellaneous herbs was shown to have the highest nitrogen-fixing activity. The loss of gaseous nitrogen during denitrification was insignificant due to the low nitrifying activity of the soils named above. N2O uptake by microorganisms was rather intensive in all the soils analyzed, and in illuvial-humo-ferric podzols underlying pine and spruce forests this process predominated. Podzolic sandy loam gley-like soil of a birch forest with gramineous plants and miscellaneous herbs had the highest potential for the mineralization of organic nitrogen; the rate of ammonification and nitrification in this soil was maximal. 相似文献
20.
The montane grassland soils of Europe store significant amounts of nitrogen (N), and climate change might drive their volatilization due to the stimulation of gaseous nitrous oxide (N2O) and dinitrogen (N2) losses. Hence, a thorough, mechanistic understanding of the processes responsible for N loss and retention such as denitrification and dissimilatory nitrate reduction to ammonium (DNRA) in these soils is urgently needed. Here we aimed to explore the relationships between denitrifier gene abundance and expression with N2 and N2O production and the importance of DNRA versus denitrification in nitrate consumption and N2O production for typical montane grassland soils of Southern Germany. In a laboratory incubation experiment with glucose and nitrate addition, we combined direct measurements of N2O and N2 production with a molecular analysis of the denitrifier communities involved in nitrite, nitric oxide (NO) and N2O reduction and with the quantification of DNRA. The soils originated from a space-for-time climate change experiment, where intact plant-soil mesocosms were exposed for three years either to ambient conditions at a high elevation site (“HE” control treatment) or to predicted climate change conditions (warming, reduced summer precipitation and reduced winter snow cover) by translocation to lower elevation (“LE” climate change treatment).The abundance (DNA) of cnorB genes was significantly reduced in LE soils, whereas the abundance of nosZ genes did not differ between the HE and LE soils. However, the decreased abundance of cnorB genes unexpectedly resulted in slightly increased rather than decreased potential N2O emissions. This effect could be explained by the increased levels of cnorB mRNA and, therefore, the higher physiological activity of the NO reducers in the LE soils. In contrast with the DNA levels, the dynamics of the cnorB mRNA levels followed N2O emission patterns, whereas the nosZ expression was strongly correlated with the N2 emission (R2 = 0.83). The potential rates of DNRA were approximately one-third of the rates of denitrification, and DNRA was not a source for N2O.We conclude that DNRA significantly competes with denitrification in these soils, thus contributing to N conservation. This work demonstrates that the molecular analysis of nosZ gene expression has great potential to contribute to solving the enigmatic problem of understanding N2 loss from soil. 相似文献