A three-dimensional model of the global ammonia cycle   总被引：16，自引：0，他引：16  

Frank J. Dentener  Paul J. Crutzen 《Journal of Atmospheric Chemistry》1994,19(4):331-369

Using a three-dimensional (3-D) transport model of the troposphere, we calculated the global distributions of ammonia (NH₃) and ammonium (NH ₄ ⁺ ), taking into account removal of NH₃ on acidic aerosols, in liquid water clouds and by reaction with OH. Our estimated global 10°×10° NH₃ emission inventory of 45 Tg N-NH₃ yr^– provides a reasonable agreement between calculated wet NH ₄ ⁺ deposition and measurements and of measured and modeled NH ₄ ⁺ in aerosols, although in Africa and Asia especially discrepancies exist.NH₃ emissions from natural continental ecosystems were calculated applying a canopy compensation point and oceanic NH₃ emissions were related to those of DMS (dimethylsulfide). In many regions of the earth, the pH found in rain and cloud water can be attributed to acidity derived from NO, SO₂ and DMS emissions and alkalinity from NH₃. In the remote lower troposphere, sulfate aerosols are calculated to be almost neutralized to ammonium sulfate (NH₄)₂SO₄, whereas in the middle and upper troposphere, according to our calculations, the aerosol should be more acidic, as a result of the oxidation of DMS and SO₂ throughout the troposphere and removal of NH₃ on acidic aerosols at lower heights. Although the removal of NH₃ by reaction with the OH radical is relatively slow, the intermediate NH₂ radical can provide a substantial annual N₂O source of 0.9 _–0.4 ^+0.9 Tg, thus contributing byca. 5% to estimated global N₂O production. The oxidation by OH of NH₃ from anthropogenic sources accounts for 10% of the estimated total anthropogenic sources of N₂O. This source was not accounted for in previous studies, and is mainly located in the tropics, which have high NH₃ and OH concentrations. Biomass burning plumes, containing high NO _x and NH₃ concentrations provide favourable conditions for gas phase N₂O production. This source is probably underestimated in this model study, due to the coarse resolution of the 3-D model, and the rather low biomass burning NH₃ and NO _x emissions adopted. The estimate depends heavily on poorly known concentrations of NH₃ (and NO _x ) in the tropics, and uncertainties in the rate constants of the reactions NH₂ + NO₂ N₂O + H₂O (R4), and NH₂ + O₃ NH₂O + O₂ (R7).  相似文献   

Accommodation coefficient for trace gas uptake using deposition profile measurement in an annular reactor     

I. M. Msibi  J. P. Shi  Roy M. Harrison 《Journal of Atmospheric Chemistry》1993,17(4):339-351

A simple and inexpensive procedure is presented for the measurement of gaseous accommodation coefficients upon liquid or solid surfaces. The gas of interest is passed in laminar flow through an annular reactor and the profile of deposition is subsequently determined. The Cooney-Kim-Davies theoretical treatment of deposition in cylindrical systems is adapted to describe uptake on the walls of the annular reactor as a function of accommodation coefficient and diffusion coefficient. The accommodation coefficient () of ammonia on oxalic acid is determined in both cylindrical and annular systems and good agreement is found. Uptake of nitrogen dioxide on wet alkaline surfaces yields a value for of 2.5×10^–4, and on solely wet surfaces a value of 8.7×10^–5. Nitric and nitrous acids deposit to aqueous sodium carbonate/glycerol surfaces with values of of 1.5 × 10^–2 and 4.3×10^–3, respectively.  相似文献   

污染源、气象条件变化对我国SO2浓度及硫沉降量分布的影响   总被引：9，自引：1，他引：9  

张新玲  安俊岭  程新金  程炜 《大气科学》2003,27(5):939-947

用三维欧拉型污染物长距离输送模式,模拟了中国大陆SOx的分布,并采用不同时期(1975、1980、1987年)的污染源与气象场资料,分析了污染源与气象条件变化对SOx分布产生的影响.研究表明,在该期间中国SOx污染比较严重的地区,气象条件变化导致SO2浓度和硫沉降量的相对变化通常在20%左右;污染源对SO2浓度与硫沉降量的作用通常大于气象条件,污染源变化产生的SO2浓度与硫沉降量的相对变化率为气象条件变化的几倍,甚至1～2个量级,尤其SOx污染比较严重的地区更为明显;但对西北及青藏高原地区,在源排放量变化不大,而气象条件变化较显著时,气象条件的作用通常大于排放源的影响.  相似文献   

锰氧化物和氢氧化物中的孔道结构矿物及其环境属性   总被引：6，自引：0，他引：6  

刘瑞  秦善  鲁安怀  郑喜珅  王丽娟  赵东军 《矿物岩石》2003,23(4):28-33

运用晶体化学理论，通过矿物孔道结构的基本概念，描述软锰矿、拉锰矿、恩苏塔锰矿、锰钡矿、锰钾矿、锰铅矿、水锰矿、斜方水锰矿、钡硬锰矿和钙锰矿等矿物的孔道结构特征。总结出孔道结构锰氧化物和氢氧化物矿物在环境修复和治理中的吸附效应、孔道效应、催化效应、氧化还原效应以及纳米效应，并展望孔道结构锰氧化物和氢氧化物矿物在环境属性开发领域的应用前景。  相似文献   

HNO3-KClO3-NH4Cl分解I2-CCl4萃取光度法测定矿石中的铜     

沈友 《矿物岩石》2002,22(1):75-76

利用HNO3－KClO3饱和液溶解矿样后，加NH4Cl蒸干破坏氮的氧化物，用六偏磷酸钠作掩蔽剂，采用I2－CCl4萃取光度法测定矿石中的铜，取得了较为满意的结果。  相似文献   

锰的氧化物和氢氧化物在污染水体净化中的应用研究现状   总被引：17，自引：1，他引：17  

高翔  鲁安怀  郑辙  郑喜坤  秦善 《矿物岩石》2002,22(1):77-82

经过对锰的氧化物和氢氧化物在净化污染水体中的应用综合研究，发现该氧化物和氢氧化物样品能有效去除污染水体中的有毒有害金属离子和 氧化降解苯酚、2－丙醇、苯及印染废水等有机物，其污染净化能力主要是基于表面络合反应、表面离子交换作用和变价元素的氧化还原作用。同时介绍了锰氧化物和氢氧化物所具有的4个环境属性；离子交换、氧化还原、粒径效应和孔道效应，提出将结构特征与环境化学有机结合，深入探讨其环境属性与污染净化能力之间的关系是目前主要的研究方向。  相似文献   

甘肃省窑街矿区一号井六采区瓦斯地质特征          下载免费PDF全文

王仲学 《甘肃地质》2008,(3):58-63

甘肃省窑街矿区一号矿井六采区为煤与二氧化碳（含甲烷等混合气体）突出矿井,矿井内瓦斯成分以二氧化碳为主。本文通过对六采区勘探阶段钻孔和采煤工作面中煤二层瓦斯资料的分析、对比,参考邻近矿井的瓦斯特征,总结了六采区瓦斯赋存、相对涌出量及其与各种地质因素之间的关系,为矿井生产中开展瓦斯与二氧化碳突出预测提供参考。  相似文献   

固相合成法制备六角薄板状CeO2纳米晶     

李纲  张其春  周如江 《矿物岩石》2007,27(3):17-22

以分子量为600的聚乙二醇(PEG600)为分散剂,通过Ce(NO3)3.6H2O和无水Na2CO3的固相反应制备出混相碳酸铈盐[Ce2O(CO3)2.H2O和Ce2(CO3)3.8H2O]前驱体,热分解该前驱体获得CeO2纳米晶。XRD研究表明,产物归属于立方晶系的方铈石相,空间群为Fm3m。混相碳酸铈盐前驱体的反应活性较高,350℃热处理已使其分解完全,获得平均晶粒度仅为6.5 nm的纯CeO2纳米粉体,600℃焙烧产物的平均晶粒度达到27.1 nm,该温度下获得的CeO2微粒呈薄板状,板面平滑,大体呈规整的六边形,板径主要在30 nm~40 nm之间,径/厚比为5~7。在透射电镜下直接观察到的平均颗粒度与采用Scherrer公式计算的平均晶粒度相近,反映出由此固相合成法制备的纳米粉体颗粒较为均匀,从团聚体生长出来的大颗粒较少。  相似文献   

Iron oxide precipitate in seepage of groundwater from a landslide slip zone   总被引：2，自引：0，他引：2  

Guodong Zheng  Yuhua Lang  M. Miyahara  T. Nozaki  T. Haruaki 《Environmental Geology》2007,51(8):1455-1464

Orange precipitate was collected at the mouth of groundwater drainage tubes from the Kumanashi Landslide slip zone in Toyama prefecture, Northwest Japan. Data from XRF, X-ray diffraction, and Mössbauer spectroscopy determined the precipitate as hydrous ferric oxide (HFO) bearing multi-elements such as phosphorous, silica, calcium, etc. The occurrence of HFO may indicate an oxidation of ferrous iron in the percolated groundwater from the slip zone. Moreover, the precipitate iron should be mobilized with groundwater circulation from the slip zone, whose reducing condition was determined by the iron speciation on the same type of landslide profiles within the study area in previous studies. The HFO precipitate may be considered as a secondary reliable indicator to locate the seepage of a slip zone on surface, especially for a landslide newly investigated under wet-warm climate.  相似文献   

南大洋大气氧化亚氮分布特征          下载免费PDF全文

詹力扬  陈立奇 《极地研究》2007,19(1):49-60

在执行中国第21次南极科学考察任务期间,于2004年11月15日至2005年2月2日在南大洋(澳大利亚以南以及中山站和长城站之间环绕南极海域)航线上采集大气氧化亚氮样品,并带回陆地实验室分析。结果显示,大气氧化亚氮浓度由澳大利亚至中山站航段的(309.6±1.6)nL/L上升至环绕南极冰边缘海区航段的(320.0±1.2)nL/L。这种南大洋大气中氧化亚氮浓度随纬度升高而升高的特征,可能与洋流作用,季节性海冰融化、生物作用以及近岸等的影响因素有关。  相似文献