Simulating estuarine nitrous oxide production by means of a dynamic model     

Rodrigues PP  Barnes J  Upstill-Goddard RC 《Marine pollution bulletin》2007,54(2):164-172

We describe a dynamic model developed from a commercially available modeling package (ECoS-III) to simulate estuarine dissolved inorganic nitrogen (DIN) dynamics, and consequent N(2)O production and atmospheric flux on the timescale of tidal cycles. Simulated model state variables were NH(4)(+), NO(3)(-) and N(2)O concentrations, and salinity. Model outputs were evaluated through comparison with summer field data for the Tyne estuary, UK. The model adequately reproduced the observed axial profiles of NH(4)(+), NO(3)(-) and N(2)O concentrations. Nitrification was shown to be the dominant N(2)O source and estimates of the ratios nitrification to DIN load and N(2)O emission to DIN load are considerably lower than the corresponding values adopted in global scale models of estuarine N(2)O emissions based on DIN transformations. Hence our results are consistent with the requirement imposed by atmospheric N(2)O growth rate constraints that the amount of atmospheric N(2)O arising from agriculturally related sources, including estuarine transformations of N, be revised downward.  相似文献   

Intracellular and extracellular mineralization of a microbial community in the Edmond deep-sea vent field environment     

Xiaotong Peng  Jiangtao Li  Jiwei Li  Shun Chen  Huiqiang Yao  Zijun Wu 《Sedimentary Geology》2010,229(4):193-368

Microbial biomineralization in submarine hydrothermal environments provides an insight into the formation of vent microfossils and the interactions between microbes, elements and minerals throughout the geological record. Here, we investigate microbial biomineralization of a deep-sea vent community in the Edmond vent field and provide ultrastructural evidence for the formation of microfossils and biogenic iron-rich minerals related to Archaea and Bacteria. Environmental scanning electron microscopy (ESEM) analysis shows that filamentous and spiral microbes are encrusted by a non-crystalline silica matrix and minor amounts of iron oxides. Examination by transmission electron microscopy (TEM) reveals acicular iron-rich particles and aggregates that occur either intracellularly or extracellularly. A culture-independent molecular phylogenetic analysis demonstrates a diverse range of Bacteria and Archaea, the majority of which are related to sulfur metabolism in the microbial mats. Both Archaea and Bacteria have undergone silicification, in a similar manner to microorganisms in some terrestrial hot springs and indicating that silicification may be driven by silica supersaturation and polymerization. Formation mechanisms of intracellular and extracellular iron oxides associated with microbes are discussed. These results enhance our understanding of microbial mineralization in extreme environments, which may be widespread in the Earth's modern and ancient hydrothermal vent fields.  相似文献   

元素活动态测量的分析方法   总被引：5，自引：1，他引：4  

卢荫庥  白金峰 《物探与化探》2000,24(1)

发展了元素活动态各相中１１ 种以上元素的分析方法,讨论了提取操作和分析、测定中的关键  相似文献   

土壤氧化亚氮产生、排放及其影响因素   总被引：45，自引：0，他引：45  

齐玉春  董云社 《地理学报》1999,54(6):534-542

全球变化对人类生存环境的变化有着十分重要的影响,ＣＯ２、ＣＨ４、Ｎ２Ｏ等气体排放量的增加是目前全球气候变化的主要诱因之一。因此,对于温室气体的研究一直以来都是全球气候变化研究的热点,其中,Ｎ２Ｏ又其其增温潜势力大,滞留大气时间长、破坏臭氧层等特点受到格外的关注,对于Ｎ２Ｏ等温室源与汇,产生机制、影响因素以及相应减排措施的研究具有十分重要的现实意义,本文拟就目前国内外土壤Ｎ２Ｏ排放的相关研究作一概述  相似文献   

海洋沉积物中氧化亚铁的分析测定   总被引：2，自引：0，他引：2  

郑凯清  张仲平 《岩矿测试》1999,18(3):198-200

海洋沉积物试样用Ｈ２Ｏ２－ＨＡｃ浸取,用以除去干扰测定ＦｅＯ的锰化合物和硫化珠,并以Ｈ２ＳＯ３－Ｎａ２ＳＯ３混合溶液破坏过乘的Ｈ２Ｏ２,不需过滤分离,即可用ＨＦ－Ｈ２ＳＯ４分解试样,Ｋ２Ｃｒ２Ｏ７标准溶液滴定ＦｅＯ。方法经海洋沉积物国家标准物质分析验证,结果与参考值相符,ＲＳＤ为６．３３％。  相似文献   

The Measurement of Active Chlorine in the Atmosphere by Chemical Amplification     

D. Perner  T. Arnold  J. Crowley  T. Klüpfel  M. Martinez  R. Seuwen 《Journal of Atmospheric Chemistry》1999,34(1):9-20

Chemical amplification, CA, a method commonly used for the detection of peroxy radicals, HO₂ and RO₂, was found to be sensitive towards ClOx (Cl+ClO+OClO) as well. ClOx is reduced by NO to Cl atoms which react with carbon monoxide in the presence of O₂. The reaction sequence thus initiated oxidizes CO to CO₂ and NO to NO₂, with a chain length of 300 ± 60. This allows the atmospheric ClOx content to be measured under ambient conditions with a detection limit of better than 1 ppt. In parallel peroxy radicals are indicated with a chain length of 160 ± 15. Chemical amplification is not specific and does not indicate which radical chain it is seeing. Identification relies solely on plausibility. During the ARCtic Tropospheric Ozone Chemistry (ARCTOC) campaign in spring 1995 and 1996 the CA technique was used at Ny-Ålesund. ClOx at mixing ratios of up to 2 ppt were found in the boundary layer under certain conditions. The low concentrations of ClOx indicate that the arctic boundary ozone depletion is mainly driven by bromine.  相似文献   

DOAS Zenith Sky Observations: 2. Seasonal Variation of BrO Over Bremen (53°N) 1994-1995     

A. Richter  M. Eisinger  A. Ladstätter-weißenmayer  J.P. Burrows 《Journal of Atmospheric Chemistry》1999,32(1):83-99

Zenith sky observations of BrO over Bremen (53°N) are reported for the period of September 1994 to January 1996. BrO differential slant columns between 90° and 80° solar zenith angle showed a strong seasonal variation between a winter maximum of 1.9·1014 molec/cm2 and a summer minimum of 0.6·1014 molec/cm2. The seasonal variation in BrO twilight values is shown to be inversely correlated with NO2 columns in agreement with current knowledge of gas phase chemistry of bromine. In contrast to model predictions, no significant difference between morning and evening BrO measurements was observed. During a 6 day polar vortex excursion to mid-latitudes OClO could be measured above Bremen indicating chlorine activation in the vortex air. No significant increase in BrO differential slant columns was detected during this time.  相似文献   

Fe23+Sn3O9,一个未定名的斜钒钛矿族的铁、锡氧化物     

张如柏  张玉玉  龚夏生 《矿物岩石》2005,25(2):11-14

Fe,Sn氧化物矿产于四川雪宝顶钨锡矿床中,与之紧密共生的矿物是黑气电石,白云母,石英等,Fe-Sn氧化物呈细小的不规则颗粒嵌在锡石中,粒度大小为0.013 mm～0.052 mm之间,偶有个别大的颗粒(d=0.28 mm)淡红褐色,条痕无色,玻璃-金刚光泽,无解理,(因大小硬度无法测定),Dx=5.93 g/cm3.在偏光镜下淡黄褐色,多色性弱,明显的非均质性,按N=1+dk公式,获得N=2.11,矿物的的化学成份SnO273.70,TiO20.60,Fe 2O3 25.26,总计99.56(7个不同测点的平均值),计算出化学式为Fe 23+Sn3O9.矿物的强X射线值3.702(15,511),3.445(5,901),3.348(100,505),3.264(14,711),3.114(40,712),1.487(10,033),单斜晶系,晶胞参数a=3.375 nm,b=0.457 nm,c=2.001nm,β=93°24',V=3.080 74 nm3,Z=18.  相似文献   

天然锰钾矿催化活性实验研究   总被引：1，自引：1，他引：0  

赵东军  郭延军  鲁安怀  王丽娟  郑喜坤  刘瑞 《矿物岩石》2005,25(1):20-24

利用天然锰的氧化物矿物及合成MnO2催化分解过氧化氢溶液．对比研究锰钾矿的催化活性。在0℃下锰钾矿催化分解H2O2的活性远大于天然软锰矿、恩苏塔矿和分析纯MnO2,原因是锰钾矿具有较大的比表面积及特殊的晶体化学特征。锰钾矿分解不同浓度H2O2溶液的反应能很好遵循langmuir—Hinshelwood动力方程式。XRD分析表明锰钾矿反应后结构未发生改变,重复实验锰钾矿催化分解H2O2的活性未见降低。  相似文献   

The Mechanisms of High N2O Emissions from Greenhouse Vegetable Field Soils     

《洁净——土壤、空气、水》2017,45(10)

  相似文献