biological activity of ancient cultivated soil with buried horizons (the iverskii monastery, XVII century)

The biological activity of an ancient cultivated soil that has been in intense agricultural use since approximately the first half of the XVII century was studied. The potential biological activity of the buried horizon of the ancient cultivated soil was higher than that of its modern horizon or that of the noncultivated soil of an adjacent territory occurring under similar lithological and geomorphological conditions. A decreased rate of oxidative processes (decreased rates of CO₂ production and CH₄ oxidation) and an increased rate of reductive processes (denitrification and nitrogen fixation) were found in the buried horizon. A high potential denitrification activity (with predominant formation of nitrous oxide) was found in the buried horizon; in the upper horizon, the end product was molecular nitrogen.     

Simulation of field scale denitrification losses from soils under grass ley and barley

Denitrification losses from soils under barley and grass ley crops were simulated. The model, which includes the major processes determining inputs, transformations and outputs of nitrogen in arable soils, represents a scale compatible with information generally available in agricultural field research. The denitrification part of the model includes a field potential denitrification rate and functions for the effect of soil aeration status, soil temperature and soil nitrate content. Easily metabolizable organic matter is assumed not to limit denitrification. Simulated values were compared with denitrification measurements made during two growing seasons in the barley and grass ley treatments of a field experiment in central Sweden.Calibration revealed that the optimal parameter values describing the effect of soil aeration on denitrification rates were similar for both treatments. The response function derived agreed well with two data sets found in the literature. The potential denitrification rate constant, derived in the simulations, was higher for grass ley than for barley, which was consistent with the differences in overall rates of carbon and nitrogen turnover found between treatments.The simulated mean denitrification rates for the two seasons were within 20% of the mean of the measured values. However, simulated denitrification showed less temporal variability and a less skewed frequency distribution than measured denitrification. Some of the measured denitrification events not explained by the model could have been due to the stimulating effects of soil drying/wetting and freezing/thawing on microbial activity.     

Biological Activity in Modern and Buried Soils of the Historical Center of St. Petersburg

Biological activity in the urban modern and medieval soils of St. Petersburg was determined using soil samples taken from sections located at the historical center of this city nearby the Kazan Cathedral and the Twelve Colleges building (now the main building of St. Petersburg State University) and on the site where the Swedish fortress Nienshants formerly existed. The studied parameters of biological activity included the rate of microbial transformation of organic matter under aerobic and anaerobic conditions, the intensity of denitrification and nitrogen fixation, and the amount of microbial biomass. This investigation is the first attempt to comparatively study modern urban anthropogenically impacted soils and buried soils that had formed the soil cover of this region before St. Petersburg was founded. The major microbiological and physicochemical parameters of the soils were subjected to correlation analysis.     

Spatially tripartite interactions of denitrifiers in arctic ecosystems: activities, functional groups and soil resources

Soil denitrification is one of the most significant contributors to global nitrous oxide (N(2) O) emissions, and spatial patterns of denitrifying communities and their functions may reveal the factors that drive denitrification potential and functional consortia. Although denitrifier spatial patterns have been studied extensively in most soil ecosystems, little is known about these processes in arctic soils. This study aimed to unravel the spatial relationships among denitrifier abundance, denitrification potential and soil resources in 279 soil samples collected from three Canadian arctic ecosystems encompassing 7° in latitude and 27° in longitude. The abundance of nirS (10(6) -10(8) copies?g(-1) dry soil), nirK (10(3) -10(7) copies?g(-1) dry soil) and nosZ (10(6) -10(7) copies?g(-1) dry soil) genes in these soils is in the similar range as non-arctic soil ecosystems. Potential denitrification in Organic Cryosols (1034?ng?N(2) O-N?g(-1) soil) was 5-11 times higher than Static/Turbic Cryosols and the overall denitrification potential in Cryosols was also comparable to other ecosystems. We found denitrifier functional groups and potential denitrification were highly spatially dependent within a scale of 5?m. Functional groups and soil resources were significantly (P?相似文献   

Biological activity in the modern and buried soils of the St.Petersburg's historical center

Biological activity in the urban modern and medieval soils of St. Petersburg was determined using soil samples taken from sections located at the historical center of this city nearby the Kazan Cathedral, the Twelve Colleges building (now the main building of St. Petersburg State University), and on the site where the Swedish fortress Nienshants formerly existed. The studied parameters of biological activity included the microbial transformation rate of organic matter under aerobic and anaerobic conditions, the intensity of denitrification and nitrogen fixation, and the amount of microbial biomass. This investigation is the first attempt to comparatively study modern urban anthropogenically impacted soils and buried soils that had formed the soil cover of this region before St. Petersburg was founded. The major microbiological and physicochemical parameters of the soils were subjected to correlation analysis.     

Comparative study of biological nutrient removal (BNR) processes with sedimentation and membrane-based separation

A membrane-enhanced biological phosphorus removal (MEBPR) process was operated in parallel with a conventional EBPR (CEBPR) process under challenging operating conditions to uncover fundamental differences in their ability to remove chemical oxygen demand (COD), nitrogen (N), and phosphorus (P) from municipal wastewater. Both systems exhibited the same potential to achieve excellent soluble-P removal when a favorable COD to P ratio was maintained in the influent. The MEBPR train generated a superior effluent quality when measured as total P. The CEBPR effluent contained significantly lower levels of nitrates due to the extra denitrification occurring in the sludge blanket of the secondary clarifier. The observed sludge yield in the MEBPR system was estimated to be between 0.23 and 0.28 g VSS/g COD, and this was 15% lower than the CEBPR sludge yield. When the influent volatile fatty acids (VFAs) became limiting, the CEBPR train exhibited better performance in the removal of soluble-P, due to the higher observed sludge yield and an overall greater denitrification activity that led to a more efficient use of VFAs in the anaerobic zone. After experiencing a severe deterioration of the biological P activity in both processes, the MEBPR train exhibited faster recovery than the CEBPR side. In this experimental work, it was demonstrated that an MEBPR process can sustain long-term satisfactory bio-P performance at HRTs as low as 7 h. However, the lower sludge yield and the reduced denitrification capacity are two important factors that impact the design of high rate membrane-assisted biological nutrient removal (BNR) processes.     

Specific Features of Nitrogen Transformation in the Soddy-Podsolic Soil in the Colonies of the Common Vole Microtus arvalis

The influence of common vole Microtus arvalison processes of nitrogen fixation and denitrification in the soddy-podsolic soil was studied. In the common vole colonies, the level of nitrogen fixation was reliably lower and that of denitrification higher, than in the control soil outside these colonies. Nitrogen-containing excretory products of voles accumulating in the soil are among the main factors that determine the activity of these processes.     

川西亚高山针叶林不同恢复阶段土壤的硝化和反硝化作用

 采用气压过程分离(Barometric process separation, BaPS)技术对川西亚高山针叶林不同恢复 阶段土壤的总硝化和反硝化作用速率进行了测定,结果表明：川西亚高山针叶林不同恢复阶段土壤的总硝化和反硝化速率差异不显著(p<0.05),不同恢复阶段土壤总硝化作用的 Q10值 差异不显著(p<0.05);总硝化作用速率与土壤含水量呈显著正相关(p<0.05),与土 壤pH值、 土壤有机质、全氮及C/N相关不显著;不同恢复阶段土壤反硝化速率均维持在一个较低的水 平,反硝化速率与土壤中的C/N显著正相关(p<0.05),与土壤含水量、pH值、有机质及全氮相关不显著。与反硝化作用相比,硝化作用对亚高山针叶林土壤氮损失的影响可能更大     

Simultaneous nitrification,denitrification, and phosphorus removal in a lab-scale sequencing batch reactor

Simultaneous nitrification and denitrification (SND) via the nitrite pathway and anaerobic-anoxic-enhanced biological phosphorus removal (EBPR) are two processes that can significantly reduce the energy and COD demand for nitrogen and phosphorus removal. The combination of these two processes has the potential of achieving simultaneous nitrogen and phosphorus removal with a minimal requirement for COD. A lab-scale sequencing batch reactor (SBR) was operated in alternating anaerobic-aerobic mode with a low dissolved oxygen (DO) concentration (0.5 mg/L) during the aerobic period, and was demonstrated to accomplish nitrification, denitrification, and phosphorus removal. Under anaerobic conditions, COD was taken up and converted to polyhydroxyalkanoates (PHAs), accompanied by phosphorus release. In the subsequent aerobic stage, PHA was oxidized and phosphorus was taken up to <0.5 mg/L by the end of the cycle. Ammonia was also oxidized during the aerobic period, but without accumulation of nitrite or nitrate in the system, indicating the occurrence of simultaneous nitrification and denitrification. However, off-gas analysis showed that the final denitrification product was mainly nitrous oxide (N(2)O), not N(2). Further experimental results demonstrated that nitrogen removal was via nitrite, not nitrate. These experiments also showed that denitrifying glycogen-accumulating organisms (DGAOs), rather than denitrifying polyphosphate-accumulating organisms (DPAOs), were responsible for the denitrification activity.     

Abundance of microbial genes associated with nitrogen cycling as indices of biogeochemical process rates across a vegetation gradient in Alaska

Nitrification and denitrification processes are crucial to plant nutrient availability, eutrophication and greenhouse gas production both locally and globally. Unravelling the major environmental predictors for nitrification and denitrification is thus pivotal in order to understand and model environmental nitrogen (N) cycling. Here, we sampled five plant community types characteristic of interior Alaska, including black spruce, bog birch, tussock grass and two fens. We assessed abundance of functional genes affiliated with nitrification (bacterial and archaeal amoA) and denitrification (nirK/S and nosZ) using qPCR, soil characteristics, potential nitrification and denitrification rates (PNR and PDR) and gross mineralization rates. The main chemical and biological predictors for PNR and PDR were assigned through path analysis. The potential N cycling rates varied dramatically between sites, from some of the highest (in fens) to some of the lowest (in black spruce) measured globally. Based on path analysis, functional gene abundances were the most important variables to predict potential rates. PNR was best explained by bacterial amoA gene abundance followed by ammonium content, whereas PDR was best explained directly by nosZ gene abundance and indirectly by nirK/S gene abundance and nitrate. Hence, functional gene abundance is a valuable index that integrates recent environmental history and recent process activity, and therefore is a good predictor of potential rates. The results of this study contribute to our understanding of the relative importance of different biological and chemical factors in driving the potential for nitrification and denitrification across terrestrial ecosystems.     

长期施肥制度对稻田土壤反硝化细菌群落活性和结构的影响

以中国科学院桃源农业生态试验站长期定位施肥试验为平台,研究了3种长期施肥制度(对照不施肥-CK,化学施肥-NPK,化学施肥+有机肥-NPKOM)下土壤反硝化速率的差异.同时,以硝酸还原酶基因(narG)作为反硝化细菌的功能标志物,分析了施肥对反硝化细菌群落结构和多样性的影响.结果表明,长期施用有机肥的土壤反硝化速率,反硝化菌多样性都高于对照和施用化肥处理.从3个处理的土壤样品中共获得35个narG基因的可操作分类单元(OTU)主要分布在两个簇,与变形菌门(Proteobacteria)和放线菌门(Actinobacteria)的反硝化细菌有一定的亲缘关系,均为首次从土壤中克隆.Shannon多样性指数显示,NPKOM处理的narG基因多样性最高,CK处理次之,NPK处理最低.LUBSHUFF软件对narG基因群落组成的分析显示,施有机肥后含narG基因的细菌群落组成与CK之间有显著性差异(P<0.05),而化肥(NPK)没有产生显著影响.实验结果为进一步研究亚热带地区水稻土反硝化作用及反硝化功能菌提供了重要的依据.     

Changes in potential denitrification and respiration during the cold storage of soils

The denitrification potential in moderately fertilized soil sampled four times during 1995 decreased significantly after cold storage, at 4 +/- 2 degrees C for 1 week. Prolonged storage (up to 24 weeks) resulted in a further decrease of denitrification potential which dropped to 38-54% of the original values. Similarly, denitrification potential decreased substantially during the first week of storage in differently fertilized soils. After 24 weeks of storage, denitrification potential dropped to 29-55% of that in fresh soils. The effects of storage at 4 +/- 2 degrees C on denitrification potential and respiration (determined as carbon dioxide evolution) were in general the same in moderately fertilized soils from four different sites: in all soils, depression of both the denitrification potential and potential respiration was found after 8 weeks. However, the extent to which the parameters were decreased differed from case to case. Not only the duration and storage conditions but also unidentified soil parameters are important for the persistence of biological activity in stored soils.     

Assessment of the contamination and genotoxicity of soil irrigated with wastewater

Soil structures built by litter-feeding termites are one of the main soil translocation processes in dry tropical savanna. Runways (soil sheeting) made of soil particles cemented with salivary secretions covering the dead plant pieces collected on the ground surface represent the main soil structures. The aim of this study was to determine the impact of this soil engineering activity on the microbially-mediated N transformations (nitrification and denitrification) associated with termite sheeting. We investigated the hypothesis that the physicochemical and microbial properties of termite soil sheeting depend on (i) the termite species and (ii) the type of organic substrate consumed. Soil sheeting built by two of the main savanna species, Macrotermes subhyalinus and Odontotermes nilensis, were sampled on field plots treated with three different types of litter (Acacia leaves, millet straw, both whole and ground (< 500 µm), and cattle manure). The soils organic C, total N, inorganic N, microbial biomass, potential CO₂ respiration, nitrification and denitrification were measured. For both termite species and all types of litter, the soil sheeting was enriched in organic C and inorganic N, resulting in an increase in soil respiration, whereas the microbial biomass was unchanged with respect to the reference soil. With the exception of the soil nitrification potential, the type of organic substrate did not significantly affect the properties of the soil sheeting measured. However, the nitrogen cycle was affected differently by the two termite species. In O. nilensis sheeting, the denitrification potential was reduced with respect to the reference soil, whereas the nitrification potential was inhibited in M. subhyalinus sheeting. The changes in the nitrogen cycle processes resulted in an increase in NH₄₊ and NO_3– in the termite soil sheeting, increasing the availability of nitrogen to plants. This study reinforces the importance of termites as a keystone savanna group whose building activities have an effect on tropical soil mineralization.     

Soil amendments promote denitrification in restored wetlands

Wetlands perform important ecosystem functions, including improvement of water quality through the process of denitrification. To offset the negative environmental impact of replacing wetlands with agriculture and development, the United States has a policy requiring that losses in wetland area are compensated for through wetland restoration elsewhere. However, these restored wetlands may require decades to achieve functional equivalency to natural wetlands. We evaluated the efficacy of using carbon amendments during restoration to promote denitrification potential in four restored wetlands in central New York State, United States. The amendments were straw, topsoil, and biochar, chosen to range along a gradient of carbon lability. Soil samples collected 6 years after restoration were analyzed for denitrification potential and associated soil properties, including soil carbon and nitrogen, pH, microbial biomass carbon and nitrogen, carbon lability, and potential net nitrogen mineralization and nitrification. Compared to unamended control plots, denitrification potential was approximately 3 times higher in straw‐amended plots, 8 times higher in topsoil‐amended plots, and 11 times higher in biochar‐amended plots. Denitrification potential positively correlated with both soil organic carbon and microbial biomass nitrogen, suggesting that the use of soil amendments in restorations can help stimulate the development of denitrification potential by facilitating the suite of carbon and nitrogen cycling processes that underlie this function. However, denitrification potential in a nearby natural reference wetland was at least 50 times higher than it was in the restored wetland plots, highlighting the limitations of using wetland restoration to compensate for the loss of natural wetlands.     

Feedback of carbon and nitrogen cycles enhances carbon sequestration in the terrestrial biosphere

The efforts to explain the ‘missing sink’ for anthropogenic carbon dioxide (CO₂) have included in recent years the role of nitrogen as an important constraint for biospheric carbon fluxes. We used the Nitrogen Carbon Interaction Model (NCIM) to investigate patterns of carbon and nitrogen storage in different compartments of the terrestrial biosphere as a consequence of a rising atmospheric CO₂ concentration, in combination with varying levels of nitrogen availability. This model has separate but closely coupled carbon and nitrogen cycles with a focus on soil processes and soil–plant interactions, including an active compartment of soil microorganisms decomposing litter residues and competing with plants for available nitrogen. Biological nitrogen fixation is represented as a function of vegetation nitrogen demand. The model was validated against several global datasets of soil and vegetation carbon and nitrogen pools. Five model experiments were carried out for the modeling periods 1860–2002 and 2002–2100. In these experiments we varied the nitrogen availability using different combinations of biological nitrogen fixation, denitrification, leaching of soluble nitrogen compounds with constant or rising atmospheric CO₂ concentrations. Oversupply with nitrogen, in an experiment with nitrogen fixation, but no nitrogen losses, together with constant atmospheric CO₂, led to some carbon sequestration in organismic pools, which was nearly compensated by losses of C from soil organic carbon pools. Rising atmospheric CO₂ always led to carbon sequestration in the biosphere. Considering an open nitrogen cycle including dynamic nitrogen fixation, and nitrogen losses from denitrification and leaching, the carbon sequestration in the biosphere is of a magnitude comparable to current observation based estimates of the ‘missing sink.’ A fertilization feedback between the carbon and nitrogen cycles occurred in this experiment, which was much stronger than the sum of separate influences of high nitrogen supply and rising atmospheric CO₂. The demand‐driven biological nitrogen fixation was mainly responsible for this result. For the modeling period 2002–2100, NCIM predicts continued carbon sequestration in the low range of previously published estimates, combined with a plausible rate of CO₂‐driven biological nitrogen fixation and substantial redistribution of nitrogen from soil to plant pools.     

The conversion of amino acids in soils

Summary In an investigation on the conversion of amino acids in percolated soils, it was found that during the breakdown of glutamic acid to ammonia micro-organisms developed in the soil capable of denitrifying nitrite and nitrate to gaseous nitrogen. The enrichment of a soil with these micro-organisms was studied.Drying of the enriched soil had a deleterious effect on the activity of these micro-organisms.The interaction between denitrification and soil nitrification processes was studied in soil subjected to various percolation treatments. When the denitrifying micro-organisms and their metabolites were present in the soil the amount of nitrogen lost by denitrification depended on the availability of nitrite and nitrate. When this was supplied externally, in glutamate—nitrite or glutamate—nitrate mixtures, considerable reduction occurred. Losses were less severe where nitrite and nitrate entered the system internall y by nitrification of the ammonia produced from the breakdown of the amino acid. In fresh soils there were indications that the amount of nitrification occurring during amino-acid breakdown was the important factor.All the data appeared to be consistent with the hypothesis that during the conversion of amino acids in soils a delicate balance is established between nitrification and denitrification reactions by different types of soil micro-organisms.     

二氧化钛纳米颗粒对沼泽土壤反硝化和N2O排放的影响

近年来,二氧化钛纳米颗粒（TiO₂NPs）环境释放量不断增加,并通过多种途径进入湿地生态系统,不可避免地影响到湿地生态系统环境和功能。然而,关于TiO₂NPs对沼泽土壤反硝化作用和氧化亚氮（N₂O）排放的影响机及制尚不明确。选择典型沼泽土壤,通过室内培养实验研究土壤理化性质、反硝化酶活性、反硝化速率（DNR）和N₂O排放对不同剂量TiO₂NPs 0 mg/kg （CK）、10 mg/kg （A10）、100 mg/kg （A100）、1000 mg/kg （A1000）输入的响应,探讨TiO₂NPs输入对沼泽土壤反硝化作用和N₂O排放影响的内在机制。结果表明：不同剂量TiO₂NPs处理显著降低了土壤pH （P<0.05）,A10处理显著降低土壤总有机碳（TOC）含量（P<0.01）,A1000处理显著降低硝态氮（NO₃^--N）和亚硝态氮（NO₂^--N）含量（P<0.05）。TiO₂NPs处理抑制硝酸盐还原酶（NAR）活性,促进一氧化氮还原酶（NOR）和氧化亚氮还原酶（NOS）活性（P<0.01）,A1000处理先促进后抑制了亚硝酸盐还原酶（NIR）活性（P<0.05）。不同剂量TiO₂NPs处理抑制了土壤DNR,促进了N₂O排放,TiO₂NPs处理通过抑制NIR活性,降低土壤DNR,同时通过促进NOR活性,提高N₂O排放。综上,TiO₂NPs输入通过影响反硝化还原酶活性改变沼泽土壤反硝化过程,导致沼泽土壤N₂O排放增加,改变湿地氮的源、汇功能,影响全球气候变化。为TiO₂NPs输入的湿地环境风险评估研究提供理论基础。     

Niche construction by the invasive Asian knotweeds (species complex <Emphasis Type="Italic">Fallopia</Emphasis>): impact on activity,abundance and community structure of denitrifiers and nitrifiers

Big Asian knotweeds (Fallopia spp.) are among the most invasive plant species in north-western Europe. We suggest that their success is partially explained by biological and chemical niche construction. In this paper, we explored the microbial mechanisms by which the plant modifies the nitrogen cycle. We found that Fallopia spp. decreased potential denitrification enzyme activity (DEA) by reducing soil moisture and reducing denitrifying bacteria density in the soil. The plant also reduced potential ammonia and nitrite oxydizing bacteria enzyme activities (respectively, AOEA and NOEA) in sites with high AOEA and NOEA in uninvaded situation. Modification of AOEA and NOEA were not correlated to modifications of the density of implicated bacteria. AOB and Nitrobacter-like NOB community genetic structures were significantly different in respectively two and three of the four tested sites while the genetic structure of denitrifying bacteria was not affected by invasion in none of the tested sites. Modification of nitrification and denitrification functioning in invaded soils could lead to reduced nitrogen loss from the ecosystem through nitrate leaching or volatilization of nitrous oxides and dinitrogen and could be considered as a niche construction mechanism of Fallopia.     

硝态氮异化还原机制及其主导因素研究进展

硝态氮(NO_3~-)异化还原过程通常包含反硝化和异化还原为铵(DNRA)两个方面,是土壤氮素转化的重要途径,其强度大小直接影响着硝态氮的利用和环境效应(如淋溶和氮氧化物气体排放)。反硝化和DNRA过程在反应条件、产物和影响因素等方面常会呈现出协同与竞争的交互作用机制。综述了反硝化和DNRA过程的研究进展及其二者协同竞争的作用机理,并阐述了在NO_3~-、pH、有效C、氧化还原电位(Eh)等环境条件和土壤微生物对其发生强度和产物的影响,提出了今后应在产生机理、土壤环境因素、微生物学过程以及与其他氮素转化过程耦联作用等方面亟需深入研究,以期增进对氮素循环过程的认识以及为加强氮素管理利用提供依据。     

污水土地生态处理脱氮技术的中型试验研究

地沟式污水土地生态处理工艺,是自然生态净化与人工工艺相结合的小规模污水处理回用技术。它是采用土壤毛细管浸润扩散原理的浅型土壤处理技术,在人工可控条件下,将污水科学、合理地投配到设计定型的装置内,利用污水的能量,把其所携带的污染物,通过人工基质(土壤、砂、碎石等,填料-水-微生物-植物系统)的物质循环和能量流动,逐级降解;在不同的污染负荷、水力负荷下,完成一系列物理、化学、物理化学和微生物化学、生物化学的反应。通过以贵州典型的黄壤土为主配比的人工土作为处理系统填料的现场中型试验,探讨地沟式污水土地处理系统的脱氮效果及其影响因素。地沟式污水土地生态系统对氨氮和总氮去除效果良好,去除率分别达到84 .7%和70 .7% ,出水氨氮(14 .0 mg/L )和总氮(2 4 .7mg/L ) ,达到建设部颁发的生活杂用水水质标准。对处理系统微生物数量及分布的研究表明:处理系统中氮转化细菌丰富,氨化细菌为10 3～10 6 cfu MPN/g(土壤) (cfu:形成菌落数:MPN:最大可能数量) ,亚硝化菌为10 3～10 6 MPN/g(土壤) ,硝化菌10 4～10 6 MPN/g(土壤) ,反硝化细菌为10 3～10 6 MPN/g(土壤)。由硝化/反硝化实现生物脱氮是土地生态处理系统去除总氮的主要途径;建立土壤、土壤微生物、土壤植被环境以促进硝化作用是提高总