Enzyme Activities and Microbial Communities in Subtropical Forest Soil Aggregates to Ammonium and Nitrate-Nitrogen Additions     

WEI Yan  WANG Zhongqiang  ZHANG Xinyu  YANG Hao  LIU Xiyu  LIU Wenjing 《资源与生态学报(英文版)》2017,8(3):258-267

A laboratory incubation experiment was established to examine the impacts of nitrate and ammonium nitrogen additions on soil microbial attributes of a subtropical Pinus elliottii forest ecosystem in southern China. Soils were subjected to three different treatments: the control with no nitrogen addition (CK), the ammonium nitrogen addition (NH₄⁺-N), and the nitrate nitrogen addition (NO₃^--N). Samples from bulk and two different size fractions (macroaggregate (>250 μm) and microaggregate (53-250 μm)) were analyzed for soil properties, enzyme activities and microbial communities on day 7 and 15 of the incubation. Our study demonstrated that NH₄⁺-N had a greater influence on soil microbial activities than NO₃^--N. NH₄⁺-N additions resulted in significant increases in β-1,4-glucosidase (βG) and β-1,4-N-acetyl glucosaminidase (NAG) enzyme activities in bulk, macroaggregate and microaggregate soils after 7 and 15 days incubation. NO₃^--N additions only significantly increased in βG and NAG enzyme activities in bulk, macroaggregate soils after 7 and 15 days incubation, but not in microaggregate. All NH₄⁺-N and NO₃^--N additions resulted in significant increases in gram-positive bacterial PLFAs in microaggregates. Only a significant correlation between soil nutrient contents and enzyme activities in macroaggregates was founded, which suggests that the soil aggregation structure played an important role in the determining enzyme activities.  相似文献   

FT-IR Study of the Kinetics and Products of the Reactions of Dimethylsulphide, Dimethylsulphoxide and Dimethylsulphone with Br and BrO   总被引：3，自引：0，他引：3  

B. Ballesteros  N. R. Jensen  J. Hjorth 《Journal of Atmospheric Chemistry》2002,43(2):135-150

Kinetics and products of the gas-phase reactions of dimethylsulphide (DMS), dimethylsulphoxide (DMSO) and dimethylsulphone (DMSO₂) with Br atoms and BrO radicals in air have beeninvestigated using on-line Fourier Transform Infrared Spectroscopy (FT-IR) as analytical technique at 740 ± 5 Torr total pressure and at 296 ± 3 K in a480 L reaction chamber. Using a relative rate method for determining the rate constants; the following values (expressed in cm³molecule^–1 s^–1) were found: k_DMS+Br = (4.9 ±1.0) ×10^–14, k_DMSO + Br < 6 × 10^–14,k_{DMSO 2} + Br 1 × 10^–15,k_DMSO + BrO = (1.0 ± 0.3) × 10^–14 andk_{DMSO 2} + BrO 3 × 10^–15 (allvalues are given with one on the experimental data). DMSO, SO₂, COS, CH₃SBr andCH₃SO₂Br were identified as the main sulphur containing products of the oxidation of DMS by Br atoms. From the reaction between DMSO and Br atoms, DMSO₂and CH₃SO₂Br were the only sulphur containing products thatwere identified. DMSO, DMSO₂ and SO₂ were identified as themain sulphur containing products of the reaction between DMS and BrO.DMSO₂ was found to be the only product of the reaction between DMSO and BrO. For the reactions of DMSO₂ with Br and BrO no products were identified because the reactions were too slow.The implications of these results for atmospheric chemistry are discussed.  相似文献   

The Heterogeneous Reaction of NO<Subscript>2</Subscript> with NH<Subscript>4</Subscript>Cl: A Molecular Diffusion Tube Study     

Norimichi?TakenakaEmail author  Michel?J.?Rossi 《Journal of Atmospheric Chemistry》2005,50(2):171-194

The heterogeneous interaction of nitrogen dioxide with ammonium chloride was investigated in a molecular diffusion tube experiment at 295–335 K and interpreted using Monte Carlo trajectory calculations. The surface residence time (τ_surf) of NO₂ on NH₄Cl is equal to 15 μs at 295 K, increases with temperature up to 323 K (τ_surf = 45 μs) and probably decreases beyond 323 K. The same experiment also yields uptake coefficients, γ, which are derived from the absolute number of surviving molecules effusing out of the diffusion tube. The rate of uptake of NO₂ on NH₄Cl followed a rate law first order in [NO₂] and the uptake coefficient γ is equal to 7 × 10⁻⁵ at 295 K, increases with temperature up to 323 K (γ = 2.1 × 10⁻⁴) and probably decreases beyond 323 K. Nitrous acid, water and nitrogen were detected as products. From these products, it is concluded that the reaction of NO₂ with NH₄Cl is a reverse disproportionation reaction where two moles of NO₂ result in ammonium nitrite, NH₄NO₂, as an intermediate, and nitryl chloride, NO₂Cl. NH₄NO₂ decomposes in two pathways, one to nitrous acid, HONO and NH₃, the other to nitrogen and water. The branching ratio for the production of HONO + NH₃ to that of N₂ + H₂O is approximately 20 at 298 K and increases with increasing temperature.  相似文献   

从低品位碳酸锰矿石中富集回收锰的绿色化学工艺研究   总被引：5，自引：0，他引：5  

李赋屏  朱国才  田君 《矿产与地质》2005,19(1):93-96

阐述了采用铵盐法从低品位碳酸锰矿石中富集回收锰的方法,该方法是将低品位碳酸锰矿石与NH4Cl通过研磨混合均匀,在管式炉中于450℃焙烧1h,焙砂采用热水浸取,得到氯化锰浸出溶液。用焙烧过程产生的氨气及二氧化碳气体通过真空通入浸出液,将锰沉淀下来,过滤、干燥后得到锰精矿;滤液蒸发浓缩、结晶,得到了NH4Cl固体,可以复用。结果表明,采用该工艺的锰回收率达90％以上。认为该方法是一种从低品位碳酸锰矿石中富集回收锰的绿色化学工艺。  相似文献   

Spectra of the ammonium radical: the schüler bands     

G. Herzberg 《Journal of Astrophysics and Astronomy》1984,5(2):131-138

The main bands of the Schüler system of ND₄ and NH₄ have been observed at high resolution. On the basis of these spectra, Watson, in a separate paper, has analysed the ND₄ main band showing that it represents a²F₂ → ² A₁ transition of a tetrahedral molecule. The observed wavenumber data for both ND₄ and NH₄ are presented; the latter have not yet been analysed. Isotopic bands for¹⁵ND₄,¹⁴ND₃H,¹⁴ND₂H₂,¹⁴NDH₃ have also been obtained and as previously pointed out confirm the assumed carrier of the spectrum. The much weaker bands accompanying the main Schüler band on the short and long wavelength sides are photographed at medium resolution. The interpretation of these bands in terms of the vibrational levels of upper and lower states is briefly discussed.  相似文献   

污水人工快速渗滤系统中氨氧化菌16S rDNA的DGGE分析     

马鸣超  姜昕  刘菲  李俊 《高校地质学报》2007,13(4):688-693

为了研究污水人工快速渗滤系统(CRI)中氨氧化菌的空间分布规律以及NH4-N在CRI中的迁移转化机理,从深圳运行中的CRI系统砂层填料中以5~10cm间隔垂直取12个样品,对其氨氧化菌的16SrDNA进行DGGE分析。结果表明,CRI系统中氨氧化菌菌群随着深度的增加先增多后减少,在表层至10cm处氨氧化菌约有4~5种组成,主要由某些以有机氮为降解底物的微生物和进水中被砂粒介质截流吸附的微生物组成;在20~90cm范围内氨氧化菌增加至9种左右,多样性最为丰富,是亚硝化作用发生的主要区域;而在100cm以下的范围,由于NH4-N浓度的降低或系统复氧不足,氨氧化菌迅速减少至5~6种。该研究结果证明了氨氧化菌在快渗池内分布范围的变化对NH4-N去除率的影响,即氨氧化菌在快渗池内分布的越接近中上层,对NH4-N的去除效果越好。关于CRI系统中氨氧化菌的空间分布规律及其与NH4-N去除率关系的认识,为工艺改进和效果提高提供了理论基础。  相似文献   

气相分子吸收光谱法测定土壤中铵态氮和硝态氮的含量     

吴昊  朱红霞  袁懋  许人骥  薛荔栋 《岩矿测试》2021,(1):165-171

通过测定土壤中铵态氮和硝态氮的含量,能够为农业领域土壤精准施肥和土壤的环境保护提供重要参考。目前基于分光光度法的土壤中铵态氮和硝态氮的分析方法容易受到提取试液颜色、浑浊度、其他共存离子等干扰不能直接测定,必须进行脱色等前处理操作,费时耗力。因此,本文建立了一次性同时浸提,不经脱色处理,采用气相分子吸收光谱法测定农田土壤中铵态氮和硝态氮含量的方法。利用该方法测定农田土壤中铵态氮和硝态氮,避免了繁琐的显色反应过程,一个批次样品(50个)的分析流程仅需5h。在0.10~2.00mg/L(铵态氮)和0.20~4.00mg/L(硝态氮)浓度范围内,工作曲线线性良好;方法检出限分别为0.013mg/kg及0.002mg/kg;相对标准偏差(RSD)<1%;加标回收率为96.3%~100.7%。较之基于传统分光光度法的国家标准方法,本方法在检出限、精密度和回收率等指标方面均有显著改善,能够满足农田土壤中铵态氮和硝态氮的批量精准分析需求。  相似文献   

小分子有机碳、氮源对海洋着色菌(Marichromatium gracile)生长和去除高浓度无机三态氮的影响     

蒋鹏  赵春贵  杨素萍 《海洋与湖沼》2014,45(6):1218-1224

采用高浓度无机三态氮(铵氮4NH?-N、亚硝氮2NO?-N和硝氮3NO?-N)共存的模拟海水体系,在最适生长条件下,研究了小分子有机物(糖类、有机酸、醇、有机氮)和p H对海洋着色菌(Marichromatium gracile)YL28去除水体无机三态氮的影响。结果表明:以葡萄糖、乙酸钠和乙醇为唯一碳源时,水体中的高浓度2NO?-N和3NO?-N均能被完全去除,4NH?-N的去除率分别为93.40%、84.55%和66.63%;碳源为乙酸钠时菌体生长最好,体系中添加蛋白胨或尿素,仅4NH?-N的去除效果明显降低。p H值在6.0—9.0时,该菌株对4NH?-N、2NO?-N和3NO?-N均具有去除能力。由此可知:YL28菌株对模拟海水养殖水体中高浓度无机三态氮具有良好的去除能力,高浓度有机氮化物(蛋白胨和尿素)对4NH?-N的去除能力有明显影响,但对2NO?-N和3NO?-N仍保持高效的去除能力。本研究为不产氧光合细菌制剂在水产养殖中的合理应用提供参考。  相似文献   

钾铵基聚合物泥浆在大同煤田复杂地层钻进中的应用          下载免费PDF全文

徐学军 《探矿工程》2016,43(12):45-48

煤田地质钻探中,白垩系卵石层、多层采空区及泥岩地层是一大钻进难题。一是上部长孔段砂卵层胶结松散,易垮塌;二是下部泥岩水敏性强,膨胀性大,节理裂隙发育,极易产生缩径、造浆及不同程度的渗漏;三是多层采空区的护壁问题。针对这些问题,在大同煤田复杂地层钻进中,经反复实验选用了钾铵基聚合物低固相泥浆。实践证明,采用钾铵基聚合物低固相泥浆,可有效防止孔内坍塌、掉块、缩径,预防孔内事故,提高钻进效率,降低成本,达到了正常的钻进目的。  相似文献   

Preparation of Ammonium Tungstophosphate-Calcium Alginate Composite Adsorbent and the Separation of Rubidium and Potassium     

AN Lianying  HUANG Xianjiang  ZHAO Xianyin  ZHANG Chunxi  HUANG Zhenggen 《《地质学报》英文版》2014,88(Z1):291-292

正As a kind of rare metals,rubidium is often used to prepare special glass,photomultiplier tubes,thermoelectric converter,organic catalysts and antidepressants.Rubidium forms no minerals of its own,hence,it often coexists with  相似文献