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1.
我国红壤区大气氮沉降及其农田生态环境效应   总被引:1,自引:0,他引:1  
崔键  周静  杨浩  何园球 《土壤》2015,47(2):245-251
大气氮沉降作为营养源和酸源,沉降数量的急速增加,将严重影响生态系统的生产力和稳定性,对农田生态系统的影响日益显现。本文简要介绍了大气氮沉降的概念、来源和研究方法,梳理了近年来我国红壤区大气氮沉降的形态、数量及其对农田生态系统的影响,提出了红壤农田生态系统大气氮沉降当前存在的问题及今后的发展趋势。  相似文献   

2.
江西红壤地区农田生态系统大气氮沉降通量的研究   总被引:17,自引:0,他引:17       下载免费PDF全文
王体健  刘倩  赵恒  周静  樊建凌 《土壤学报》2008,45(2):281-287
2004年12月至2005年11月在江西鹰潭中国科学院红壤生态实验站进行了为期1a的大气氮沉降的外场观测试验。本文对观测得到的数据资料进行分析,定量给出了农田生态系统大气氮化物浓度和氮沉降通量。结果表明,鹰潭地区农田下垫面大气中NH3、NOx和ON(有机氮)的平均浓度分别为24.6、3.54、7.2μgm-3。气溶胶中铵盐、硝酸盐、ON的平均浓度分别为4.16、4.64、0.92μgm-3。降水中NH4+离子、NO3-离子、ON的平均浓度分别为0.89、0.73、0.26mgL-1。全年大气氮沉降总量为N6.26gm-2,其中干沉降为N3.19gm-2,占总沉降量的51%;湿沉降为N3.07gm-2,占总沉降量的49%。无机氮沉降为N5.47gm-2,占总沉降量的87.4%;有机氮沉降为N0.79gm-2,占总沉降量的12.6%。与草地、森林、湖泊等其他下垫面相比,江西红壤地区农田下垫面大气氮沉降量相对较大,对农田生态系统氮素平衡将产生重要影响。  相似文献   

3.
山西省太原市旱作农区大气活性氮干湿沉降年度变化特征   总被引:6,自引:0,他引:6  
鉴于大气氮素沉降对整个生态系统的重要影响,我国近年来陆续开展了不同尺度的大气氮素干、湿沉降的研究,但少有农业区多年连续监测的资料。本研究利用DELTA系统、被动采样器和雨量器在山西省太原市郊区阳曲县河村旱作农业区进行了4年的监测试验,观测大气氮素干、湿沉降的时间变异。结果表明:2011年4月—2015年3月,河村4年大气活性氮NH_3、HNO_3、NO_2、颗粒态NO_3~-(pNO_3~-)、颗粒态NH_4~+(pNH_4~+)平均沉降量分别为4.50 kg(N)·hm~(-2)·a~(-1)、3.54 kg(N)·hm~(-2)·a~(-1)、2.56 kg(N)·hm~(-2)·a~(-1)、1.62 kg(N)·hm~(-2)·a~(-1)、2.75 kg(N)·hm~(-2)·a~(-1),大气氮素干沉降总量为12.38~18.95 kg(N)·hm~(-2)·a~(-1),以2011年的氮干沉降量最高,2014年的最低。2011年4月—2015年3月各月氮干沉降量与氨气沉降量之间存在显著正相关,相关系数在0.809 8~0.937 1,由此可知,该地区活性氮沉降主要受农业氨气排放的影响。河村4年雨水中NO_3~-、NH_4~+平均浓度分别为3.20 mg(N)·L~(-1)和2.43 mg(N)·L~(-1),大气氮素湿沉降11.67~41.31 kg(N)·hm~(-2)·a~(-1)。年度间氮素湿沉降存在很大差异,以2012年氮素年湿沉降量最高,2014年最低,每年大气氮素湿沉降占氮总沉降量的份额超过50%。此外,4年湿沉降中不仅NO_3~--N和NH_4~+-N之间、且二者与降雨量也呈显著线性或二次相关关系,说明降雨量对NO_3~--N和NH_4~+-N的湿沉降影响较大。本研究表明太原市旱作农区不同年份间氮素湿沉降比干沉降差异更大,且总沉降数量较高。虽然是旱作区,该地区氮素干沉降略低于湿沉降。研究结果为该地区农田氮肥施用和氮素循环监测提供了理论依据。  相似文献   

4.
[目的]系统地探究近10a中国大气氮沉降研究态势,为今后的相关研究提供科学借鉴。[方法]基于科学计量学与信息可视化分析方法,借助Citespace软件,从文献中分析近10a中国大气氮沉降研究热点及趋势。[结果]近10a来,在氮沉降背景下,森林生态系统中凋落物分解与土壤微生物特征一直是研究热点;近5a草地生态系统的研究地区更加广泛,但较少涉及林下草地;碳氮循环相关研究多集中于温带及亚热带森林区,研究内容更加丰富,研究方法向大数据分析及模型建立方向发展;大气氮沉降通量观测以水域生态系统为主,近5a来较多地结合了非点源污染及示踪技术。[结论]近10a来,中国氮沉降领域各学科交叉性和系统性增强,研究内容和尺度不断扩大,研究方法和技术趋于多样化;草地生态系统及微生物群落特征、氮沉降与全球变化及人类活动耦合关系研究成为近年来关注的热点。  相似文献   

5.
土壤是组成陆地生态系统的重要组分,其养分条件决定了植物生长状况及生产力的大小。氮是植物生长的必需营养元素和主要限制因子之一,大气氮沉降的增加会改变土壤性质,从而对植物生长造成影响。为合理利用氮沉降所带来的养分及为合理施肥提供科学依据,从大气氮沉降对土壤碳、氮、磷含量的影响,以及土壤养分有效性对氮沉降的响应、土壤盐基离子含量对氮沉降的响应3个方面就大气氮沉降对土壤养分的影响进行了综述。  相似文献   

6.
氮输入对森林土壤有机碳截存与损耗过程的影响   总被引:1,自引:0,他引:1  
大气氮沉降对受氮限制的陆地生态系统碳截存/损耗的机理尚不清楚,尤其是对土壤有机碳(SOC)的输入、转化和输出过程的认识明显不足。本文论述了外源性氮素(氮沉降、人为增氮)对凋落物分解、土壤有机碳各组分周转的影响,以及土壤呼吸各组分(根系自养呼吸、根际微生物呼吸和SOM分解)对增氮的响应等领域的最新研究进展,指出了在上述研究领域中存在的问题,并提出拟解决的途径以及未来的可能研究方向,以期为该领域的研究提供参考。  相似文献   

7.
近几十年来,随着世界经济和人口的迅速增长,全球大气活性氮排放量急剧上升[1]。活性氮大气排放的增加使得从大气沉降到地面的氮素数量也迅速增加,从而有可能导致自然或半自然生态系统(如森林、草地和湖泊等)富营养化土壤或水体酸化以及生物多样性降低等危害[2~5]。为了有效地评价大气氮沉降的生态环境效应,欧美一些国家进行了大量的氮沉降监测工作,并建立起了比较完善的氮沉降监测网络,如联合国欧洲经济委员会欧洲监测与评价计划(UN ECE-EMEP)、美国的国家大气沉降计划(NADP)和清洁空气状况与趋势网(CASTNet)以及加拿大的空气与降水监测网(CAPMoN)等。我国关于氮沉降的网络研究起步较晚,且主  相似文献   

8.
  目的  随着大气氮沉降现象加剧,其对生态系统的影响也日益严重;氮沉降改变了土壤氮库的特征,也影响了土壤中微生物群落组成和功能。采用文献计量学方法总结了近20年来国际上有关氮沉降对土壤微生物影响方面研究的特征、前沿、热点及其变化趋势。  方法  采用Citespace软件,自Web of Science核心数据库中选取2001 ~ 2020年间发表的有关大气氮沉降对土壤微生物影响方面的研究论文,从国家、学术机构、作者、期刊、关键词和学科类别等方面进行可视化分析,以阐明该研究领域的发展趋势和研究热点。  结果  结果表明,大气氮沉降对土壤微生物影响研究发文量最大的国家为美国,而发文量最大的学术机构为中国科学院,研究领域集中在环境科学、生态学和农学等学科,研究内容呈现出多学科融合趋势。  结论  目前有关大气氮沉降对土壤微生物影响方面的研究趋向于探究氮沉降影响土壤养分循环和土壤微生物对大气氮沉降响应机制。  相似文献   

9.
氮沉降对细根分解影响的研究进展   总被引:1,自引:0,他引:1  
随着人类干扰的加剧,大气中氮沉降量迅速增加,并显著影响生态系统碳循环过程。细根分解不但是陆地生态系统重要的碳汇和矿质养分库,也是土壤碳及养分的主要来源,对陆地生态系统物质和能量循环具有重要意义。细根分解是植物、土壤动物、微生物及土壤微生态系统间复杂的互作过程,氮沉降对细根分解速率的影响较为复杂,系统深入地研究氮沉降下植物、土壤动物、微生物与土壤微生态系统的相互作用方式与机理,对探索定向调控细根分解过程、预测生态系统对全球变化的响应具有重要的指导意义。对细根分解对大气氮沉降的响应进行了全面总结,系统分析和详细描述了氮沉降对细根分解关键因素的影响,及氮沉降对细根分解影响的机理;总结了目前细根分解研究中存在的问题,并对未来重点研究方向进行了展望,以期为深入研究氮沉降与陆地生态系统碳循环间的交互作用及反馈机制提供参考。  相似文献   

10.
闽西北农田生态系统中大气氮湿沉降研究   总被引:8,自引:0,他引:8  
在福建省三明市将乐县连续3年定位收集湿沉降,研究闽西北地区农田生态系统大气氮素湿沉降的浓度、沉降量以及时间变化规律。结果表明:降水中TN、TIN、DON、NH4+-N和NO3--N的平均浓度分别为1.22,0.83,0.38,0.53,0.30mg/L,无机氮与有机氮的比例达到2.18,且在每次降雨中总氮的浓度均超过水体富营养化阈值(0.2mg/L)。该地区湿沉降氮输入量有明显的季节性变化,春、夏季高,秋、冬季低。在湿沉降输入氮中NH4+-N、NO3--N和DON占总氮的比例分别为43.77%,24.78%和31.45%,湿沉降以无机氮(TIN)为主,平均年无机氮(TIN)沉降量为8.71kg/hm2,占总氮(TN)沉降量的68.55%。总氮(TN)年输入量为4.17~18.00kg/hm2,平均值为12.71kg/hm2。大气中氮素湿沉降对生态环境有一定的风险。  相似文献   

11.
Ectomycorrhizal (EM) fungi are abundant in temperate and boreal ecosystems and are understood to be an important means whereby plants can fulfill their nutrition requirements. The extent of the EM fungal involvement in accessing organic sources of N, however, remains unknown. Some EM fungi have been found to produce lignolytic and proteolytic enzymes which are necessary to depolymerize organic substrates, but this ability varies by species. Both EM fungal communities and the activities of lignolytic and proteolytic enzymes may be sensitive to changes in inorganic N availability such as through increased atmospheric deposition. Our objectives were to simulate an ecologically relevant increase in atmospheric N deposition in areas currently receiving very little exogenous N and examine changes in EM community composition, lignin degrading enzyme activity, and soil protein depolymerization. We found a distinct shift in the EM community composition following simulated atmospheric N deposition. Likewise, we found a significant decrease in the activity of lignin degrading enzymes, which could have important implications on ecosystem N and C cycling. Contrary to our hypotheses, proteolysis increased following N addition. The fact that lignolytic and proteolytic enzymes exhibit opposite responses is counterintuitive and suggests much is yet to be learned about how N addition affects global C storage by affecting the decomposition of organic matter. Our data suggest small increases in atmospheric N deposition could produce significant changes in communities of EM fungi and N and C cycles.  相似文献   

12.
于海洋  张广斌  马静  徐华 《土壤》2021,53(3):458-467
大气CO_2浓度升高是全球气候变化的主要驱动力,可直接或间接影响陆地生态系统碳氮循环。阐明稻田生态系统CH_4和N_2O排放对大气CO_2浓度升高的响应及其机制,是农业生产应对全球气候变化的重要组成部分。本文综述了国内外不同大气CO_2浓度升高模拟技术平台条件下稻田CH_4和N_2O排放的响应规律,进一步讨论分析了大气CO_2浓度升高影响CH_4和N_2O排放的相关机制,并展望了今后稻田CH_4和N_2O排放对大气CO_2浓度升高响应的主要研究方向,以期为应对全球气候变化提供理论依据和技术支撑。  相似文献   

13.
The relationship between total and metabolically active soil microbial communities can provide insight into how these communities are impacted by environmental change, which may impact the flow of energy and cycling of nutrients in the future. For example, the anthropogenic release of biologically available N has dramatically increased over the last 150 years, which can alter the processes controlling C storage in terrestrial ecosystems. In a northern hardwood forest ecosystem located in Michigan, USA, nearly 20 years of experimentally increased atmospheric N deposition has reduced forest floor decay and increased soil C storage. A microbial mechanism underlies this response, as compositional changes in the soil microbial community have been concomitantly documented with these biogeochemical changes. Here, we co-extracted DNA and RNA from decaying leaf litter to determine if experimental atmospheric N deposition has lowered the diversity and altered the composition of the whole communities of bacteria and fungi (i.e., DNA-based) and well as its active members (i.e., RNA-based). In our experiment, experimental N deposition did not affect the composition, diversity, or richness of the total forest floor fungal community, but did lower the diversity (−8%), as well as altered the composition of the active fungal community. In contrast, neither the total nor active forest floor bacterial community was significantly affected by experimental N deposition. Our results suggest that future rates of atmospheric N deposition can fundamentally alter the organization of the saprotrophic soil fungal community, key mediators of C cycling in terrestrial environments.  相似文献   

14.
模拟氮沉降对亚热带竹林不同凋落物组分分解的影响   总被引:5,自引:0,他引:5  
As an important component of the global carbon (C) budget, litter decomposition in terrestrial ecosystems is greatly affected by the increasing nitrogen (N) deposition observed globally. We hypothesized that different litter fractions derived from a single tree species may respond to N deposition differently depending on the quality of the litter substrate. To test the hypothesis, a two-year field experiment was conducted using the litterbag method in a Pleioblastus amarus plantation in the rainy region of Southwest China. Four N treatment levels were applied: control (no N added), low-N (50 kg N ha-1 year-1), medium-N (150 kg N ha-1 year-1), and high-N (300 kg N ha-1 year-1). We observed different patterns of mass loss for the three P. amarus litter fractions (leaves, sheaths, and twigs) of varying substrate quality in the control plots. There were two decomposition stages with different decay rates (fast rate in early stages and slow rate in the later stages) for leaves and sheaths, while we did not observe a slower phase for the decay of twigs during the 2-year study period. The annual decomposition rate (k) of twigs was significantly lower than that of leaves or sheaths. Addition of N slowed the decomposition of leaves and twigs in the later stages of decomposition by inhibiting the decay of lignin and cellulose, while addition of N did not affect the mass loss of sheaths during the study period. In the decomposition of all three litter fractions, experimental N deposition reduced the net N accumulation in the early stages and also decreased the net N release in the later stages. The results of this study suggest that litter substrate quality may be an important factor affecting litter decomposition in a bamboo ecosystem affected by N deposition.  相似文献   

15.
Global atmospheric nitrogen deposition has increased steadily since the 20th century, and has complex effects on terrestrial ecosystems. This work synthesized results from 54 papers and conducted a meta-analysis to evaluate the general response of 15 variables related to plant root traits to simulated nitrogen deposition. Simulated nitrogen deposition resulted in significantly decreasing fine root biomass (<2 mm diameter; −12.8%), while significantly increasing coarse root (≥2 mm diameter; +56.5%) and total root (+20.2%) biomass, but had no remarkable effect on root morphology. This suggests that simulated nitrogen deposition could stimulate carbon accumulation in root biomass. The root: shoot ratio decreased (−10.7%) suggests that aboveground biomass was more sensitive to simulated nitrogen deposition than root biomass. In addition, simulated nitrogen deposition increased the fine root nitrogen content (+17.6%), but did not affect carbon content, and thus decreased the fine root C:N ratio (−13.5%). These changes delayed the decomposition of roots, combined with increasing of the fine root turnover rate (+21.4%), which suggests that simulated nitrogen deposition could increase carbon and nutrient retention in the soil. Simulated nitrogen deposition also strongly affected the functional traits of roots, which increased root respiration (+20.7%), but decreased fungal colonization (−17.0%). The effects of simulated nitrogen deposition on the plant root systems were dependent on ecosystem and climate zone types, because soil nutrient conditions and other biotic and abiotic factors vary widely. Long-term simulated experiments, in which the experimental N-addition levels were less than twofold of the average of atmospheric nitrogen deposition, would better reflect the response of ecosystems under atmospheric nitrogen deposition. These results provide a synthetic understanding of the effects of simulated nitrogen deposition on plant root systems, as well as the mechanisms underlying the effects of simulated nitrogen deposition on plants and the terrestrial ecosystem carbon cycle.  相似文献   

16.
为揭示过量的大气氮沉降对华北落叶松人工林土壤微生物碳、氮和土壤呼吸的影响,通过对照(N0:0 g/(m^2·a))、轻度施氮(N1:8 g/(m^2·a))、重度施氮(N2:15 g/(m^2·a))3个外源施氮水平下5年的野外定点试验和观测,模拟过量氮沉降条件下华北落叶松人工林土壤微生物碳、氮和土壤呼吸的变化,旨在阐明林下土壤微生物和呼吸对过量氮沉降的响应及其对土壤碳氮循环的影响。结果表明:在5-10月生长季中,土壤微生物碳和氮的平均含量分别为1 098.93,97.31 mg/kg,二者都随土层深度的增加呈下降趋势;轻度施氮促进土壤微生物碳和氮的增加,重度施氮抑制土壤微生物碳和氮的增加;土壤微生物碳和微生物氮从生长初期5月起,5-7月呈增加趋势,7月出现峰值,8月降低,9-10月小幅增加,呈现"N"形曲线。土壤微生物碳氮比为4.94~18.54,且随施氮量增加而减小。各氮处理下,华北落叶松人工林土壤呼吸速率5,6月较低,7-8月持续增加,并在8月达到最高,9-10月逐渐降低。相关分析表明,土壤呼吸与土壤全氮、含水量、微生物碳和微生物氮含量呈极显著正相关关系,与土壤有机质呈显著正相关关系。在全球变化背景下,研究结果可为进一步明确过量大气氮沉降对森林生态系统碳氮循环的影响途径和机制研究提供重要参考。  相似文献   

17.
Wet and dry deposition of atmospheric nitrogen (N) compounds into forest ecosystems and their effect on physical, chemical and microbial processes in the soil has attracted considerable attention for many years. Still the consequences of atmospheric N deposition on N metabolism of trees and its interaction with soil microbial processes has only recently been studied. Atmospheric N deposited to the leaves is thought to enter the general N metabolism of the leaves, but the processes involved, the interaction with different metabolic pathways, and the connection between injury by atmospheric N and its metabolic conversion are largely unknown. Laboratory and field experiments have shown that N of atmospheric NO2 and NH3, deposited to the leaves of trees, is subject to long-distance transport in the phloem to the roots. This allocation can result in considerable decline of N uptake by the roots. Apparently, the flux of N from the soil into the roots can be down-regulated to an extent that equals N influx into the leaves. This down-regulation is not mediated by generally enhanced amino-N contents, but by elevated levels of particular amino acids. Field experiments confirm these results from laboratory studies: Nitrate (NO3) uptake by the roots of trees at a field sites exposed to high loads of atmospheric N is negligible, provided concentrations of Gln in the roots are high. At the ecosystem level, consequences of reduced N uptake by the roots of trees exposed to high loads of atmospheric N are (1) an increased availability of N for soil microbial processes, (2) enhanced emission of gaseous N-oxides from the soil, and (3) elevated leaching of NO3 into the ground water. How recent forest management practices aimed at transforming uniform monocultures to more structured species-rich forests will interact with these processes remains to be seen. Possible implications of these forest management practices on N metabolism in trees and N conversion in the soil are discussed particularly in relation to atmospheric N deposition.  相似文献   

18.
To date, numerous studies have employed single type nitrogen (N) addition methods in reporting influences of N deposition on soil extracellular enzymatic activities (EEA) during litter decomposition in forest ecosystems. As natural atmospheric N deposition is a set of complex compounds including inorganic N and organic N, it is essential for investigating responses of soil EEA to various mixed N fertilization. In a subtropical forest stand in Zijin Mountain, East China, various N fertilizers with different inorganic N and organic N ratios were added to soils monthly from 2008 to 2009. Samples were harvested from N fertilized and control plots every 4 months. Subsequently, six EEA were assayed. A laboratory experiment was also conducted simultaneously. Both field and laboratory experiments showed that various mixed N fertilizations revealed different influences on soil EEA. Acceleration of most soil EEA by mixed N fertilization was greater than that of single N fertilization. The majority of soil extracellular enzymes exhibited the highest activities under mixed N fertilization, with the ratio of inorganic N to organic N at 3:7. These results suggested that N type and ratio of inorganic N and organic N were important factors controlling soil EEA, and the 3:7 ratio of inorganic N and organic N may be the optimum for soil EEA.  相似文献   

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