Spartina maritima (cordgrass) rhizosediment extracellular enzymatic activity and its role in organic matter decomposition processes and metal speciation     

Bernardo Duarte  Pedro R. Almeida  & Isabel Caçador 《Marine Ecology》2009,30(S1):65-73

Seasonal monitoring was carried out to investigate the influence of extracellular enzymatic activity (EEA) on metal speciation and organic matter cycling in the rhizosediment of Spartina maritima . Heavy metal speciation was achieved by the Tessier scheme, and showed a similar pattern of variation of the organic-bound fraction, indicating a decomposition process in progress. Both humic acid and organic matter showed the same seasonal pattern. The basal respiration of the rhizosediments also presented a similar seasonal pattern, indicating a microbial degradation of organic matter. The high organic-bound fraction found in the summer gradually decreased towards the winter. This decrease was found to be related to the increase of activity of peroxidase, β- N -acetylglucosaminidase and protease. Also the activity of sulphatase was found to be related to the depletion on the exchangeable fraction, probably due to sulphide formation and consequent mobilization. The results show an interaction between several microbial activities, affecting metal speciation.  相似文献   

混合发酵产甲壳素酶发酵条件优化及粗酶部分性质研究          下载免费PDF全文

屈宁  韩宝芹  刘万顺  解卉 《海洋科学》2008,32(10):35-38

利用甲壳素作为唯一碳源从土壤中筛得的真菌d,与细菌s混合发酵,对其最适产酶条件、所产甲壳素粗酶的制取以及粗酶性质进行初步研究。结果表明,混合发酵产酶的能力与单独发酵相比显著提高,混合发酵最适培养基组分为(×10~(-2) g/mL):尿素1.0,K_2HPO_4 0.07,KH_2PO_4 0.03,MgSO_4 0.05,酵母粉0.5,甲壳素1.0,pH 5.5,接种量2%(体积分数),32℃,130 r/min培养72 h,500 mL锥形瓶培养基装量为100 mL。经过优化,发酵液中甲壳素酶活力从0.73 U/mL提升到1.19 U/mL。通过对粗酶性质初步的研究,发现该酶有较好的稳定性。  相似文献   

Fine-grained landuse characterization using ground-based pictures: a deep learning solution based on globally available data   总被引：1，自引：0，他引：1  

Shivangi Srivastava  John E. Vargas Muñoz  Sylvain Lobry  Devis Tuia 《International journal of geographical information science》2020,34(6):1117-1136

ABSTRACT

We study the problem of landuse characterization at the urban-object level using deep learning algorithms. Traditionally, this task is performed by surveys or manual photo interpretation, which are expensive and difficult to update regularly. We seek to characterize usages at the single object level and to differentiate classes such as educational institutes, hospitals and religious places by visual cues contained in side-view pictures from Google Street View (GSV). These pictures provide geo-referenced information not only about the material composition of the objects but also about their actual usage, which otherwise is difficult to capture using other classical sources of data such as aerial imagery. Since the GSV database is regularly updated, this allows to consequently update the landuse maps, at lower costs than those of authoritative surveys. Because every urban-object is imaged from a number of viewpoints with street-level pictures, we propose a deep-learning based architecture that accepts arbitrary number of GSV pictures to predict the fine-grained landuse classes at the object level. These classes are taken from OpenStreetMap. A quantitative evaluation of the area of Île-de-France, France shows that our model outperforms other deep learning-based methods, making it a suitable alternative to manual landuse characterization.  相似文献   

煤层孔隙与裂隙特征研究进展     

刘世奇  王鹤  王冉  高德燚  Ashutosh Tripathy 《沉积学报》2021,39(1):212-230

煤层孔隙与裂隙发育特征是非常规油气沉积学的重要研究内容,其研究对深入认识煤层流体赋存与传质过程微观机理、优化地质适配性开发工艺具有重要意义。煤层孔隙、裂隙成因类型复杂、尺度分布范围广、非均质性强,其发育特征是煤化作用、变质作用类型、构造演化作用、煤岩物质组成、地下流体等多因素共同作用的结果。煤化作用是其内因,构造应力作用是其主要外因,内外因作用下形成了不同煤阶、不同含煤盆地、不同构造部位煤层孔隙、裂隙发育的现今特征,而成煤物质、沉积环境、盆地埋藏史、热史等具有重要的控制作用。煤层孔隙、裂隙的研究与煤层气高效开发紧密关联,未来研究中将煤层孔隙—裂隙作为具有整体性的解吸—扩散—渗流网络加以认识更具意义,而煤层孔隙—裂隙连通网络控制的渗透率来源和有效性、纳米尺度孔隙—裂隙发育特征与结构关系、孔隙—裂隙与煤层流体之间的界面性质、多尺度孔隙—裂隙结构表征等需要进一步探讨。数字岩石物理表征技术的发展和应用为该领域的研究提供了新方法和新思路。  相似文献   

中国石油精细油藏描述进展与展望          下载免费PDF全文

陈欢庆 《中国地质》2021,48(2):424-446

结合研究实践,将中国石油精细油藏描述研究进展总结为基于开发地震技术的复杂构造精细研究、潜山复杂岩性识别技术、井震结合储层精细预测技术、特低渗透储层裂缝表征技术、砾岩储层微观孔隙结构分类研究、基于密井网资料隔夹层刻画技术、砾岩油藏水淹层解释技术、油田开发过程中储层变化规律研究、砾岩储层水流优势通道识别技术、低渗透储层定量分类评价技术、断块油藏构型建模技术和多学科剩余油综合表征技术等12个方面。总结目前精细油藏描述研究中存在8方面问题,主要包括微构造(特别是低级序断层)解释无法满足油田开发需求、单砂体边界刻画和井间预测难度很大、裂缝表征与地质建模问题、碳酸盐岩缝洞型储层定量预测十分困难、复杂储层测井解释仍需持续攻关、水流优势通道识别预测问题、剩余油表征方法单一难以满足生产需要、精细油藏描述成果管理现状无法满足工作需求。最后指出了精细油藏描述研究的发展趋势。  相似文献   

铁细菌培养过程中低分子有机酸钠盐对含硫酸根铁矿物形成的影响   总被引：1，自引：0，他引：1  

花敏  张笛  姜艾伶  熊慧欣 《岩石矿物学杂志》2021,40(4):786-794

普遍存在环境中的低分子有机酸盐对氧化亚铁硫杆菌的矿化产物(施氏矿和黄钾铁矾等铁矿物)会产生影响,从而导致环境中有毒重金属迁移转化发生变化。本文探讨了低分子有机酸钠盐对铁细菌HX3成长过程中代谢产物铁矿物的影响,并利用XRD、FTIR、FESEM和EDS对形成的铁矿物进行了表征与分析。研究结果表明,低浓度低分子有机酸钠盐的加入对细菌氧化Fe~(2+)的影响不明显,但可加速黄钾铁矾的形成;苹果酸钠的加入较柠檬酸钠和草酸钠更利于施氏矿向黄钾铁矾转变。高浓度低分子有机酸钠盐(苹果酸钠、柠檬酸钠和草酸钠依次为20、40和40mmol/L)的加入对细菌培养过程中Fe~(2+)的氧化有抑制作用;抑制影响从大到小的顺序为:苹果酸钠柠檬酸钠草酸钠。该研究结果可为含氧化亚铁硫杆菌等铁细菌的酸性矿山废水中铁矿物的形成转化和生物矿化机理提供理论参考。  相似文献   

Biodegradative potential and characterization of psychrotolerant polychlorinated biphenyl-degrading marine bacteria isolated from a coastal station in the Terra Nova Bay (Ross Sea, Antarctica)   总被引：4，自引：0，他引：4  

Michaud L  Di Marco G  Bruni V  Lo Giudice A 《Marine pollution bulletin》2007,54(11):1754-1761

Antarctic marine bacteria were screened for their ability to degrade polychlorinated biphenyls (PCB) as the sole carbon and energy source at both 4 degrees C and 15 degrees C. PCB-degrading isolates (7.1%) were identified by sequencing their 16S rDNA as Pseudoalteromonas, Psychrobacter and Arthrobacter members. One representative isolate per genera was selected for evaluating the biodegradative potential under laboratory scale and phenotypically characterized. Removal of individual PCB congeners was between 35.6% and 79.8% at 4 degrees C and between 0.4% and 82.8% at 15 degrees C. Differences in the removal patterns of PCB congeners were observed in relation to the phylogenetic affiliation: Arthrobacter isolate showed similar biodegradation efficiencies when growing at 4 degrees C and 15 degrees C, while Pseudoalteromonas better degraded PCBs at 15 degrees C. No biodegradation was detected for Psychrobacter isolate at 4 degrees C. Results obtained highlight the occurrence of PCB-degrading bacteria in Antarctic seawater and suggest the potential exploitation of autochthonous bacteria for PCB bioremediation in cold marine environments.  相似文献   

利用Radarsat-2极化雷达数据探测湿地地表特征与分类   总被引：1，自引：0，他引：1  

廖静娟  王庆 《国土资源遥感》2009,(3):70-73

利用新型的Radarsat-2极化雷达数据,结合极化雷达目标分解方法提取鄱阳湖湿地不同地表类型的极化特征量,并进行了Wishart非监督和监督分类,取得了较高的精度.研究表明,Radarsat-2卫星的全天候极化雷达成像能力将在湿地监测和制图中有较大的应用潜力.  相似文献   

A Markov Chain Model for Subsurface Characterization: Theory and Applications   总被引：18，自引：0，他引：18  

Amro Elfeki  Michel Dekking 《Mathematical Geology》2001,33(5):569-589

This paper proposes an extension of a single coupled Markov chain model to characterize heterogeneity of geological formations, and to make conditioning on any number of well data possible. The methodology is based on the concept of conditioning a Markov chain on the future states. Because the conditioning is performed in an explicit way, the methodology is efficient in terms of computer time and storage. Applications to synthetic and field data show good results.  相似文献   

Stiff soil amplification effects in the 7 September 1999 Athens (Greece) earthquake     

G. D. Bouckovalas  G. P. Kouretzis 《Soil Dynamics and Earthquake Engineering》2001,21(8):671-687

The Athens, Greece, earthquake of 7 September 1999 provided a number of reliable strong motion recordings and well-defined patterns of damage at sites with known geological and geotechnical conditions. Joint evaluation of this evidence shows that the very stiff soils of the Athens basin, compared to the nearby outcropping soft rocks, have amplified the peak horizontal acceleration by an average of 40% or more and have shifted elastic response spectra to higher periods. US and the European seismic code provisions (NEHRP-97 and EC-8), place stiff soils and soft rocks at the same site category and consequently fail to predict these adverse effects. A larger number of site categories and new site coefficients that depend on the seismic excitation frequency appear necessary in order to overcome this deficit of the codes.  相似文献