Effects of salinity on anatomical features and physiology of a semi-mangrove plant Myoporum bontioides     

H.M. Xu  N.F.Y. Tam  Q.J. Zan  M. Bai  P.K.S. Shin  L.L.P. Vrijmoed  S.G. Cheung  W.B. Liao 《Marine pollution bulletin》2014

The effect of different concentrations of NaCl, 0, 100, 200, 300 and 400 mM, on the anatomical features and physiology of Myoporum bontioides was investigated. The photosynthetic rates (Pn) were significantly reduced by salt stress, with the lowest values at 400 mM NaCl. The content of malondialdehyde (MDA), proline and soluble sugar, as well as the activities of peroxidase (POD) and catalase (CAT) increased at the beginning, but became similar to the control as the experiment proceeded. The NaCl effect on superoxide dismutase (SOD) was different from the other parameters, with a significant reduction at 400 mM NaCl at Day 7. Salt glands were found in both upper and lower epidermis, and the ratios of the thickness of palisade to spongy mesophyll tissues increased with NaCl concentrations. The medullary ray was clearly damaged by NaCl at levels of 200 and 300 mM. These results demonstrated that M. bontioides could adapt to a relatively low salinity, and was not a halophilous species.  相似文献   

Structure and function of soil microbial community in artificially planted Sonneratia apetala and S. caseolaris forests at different stand ages in Shenzhen Bay,China     

Q. Yang  A.P. Lei  F.L. Li  L.N. Liu  Q.J. Zan  P.K.S. Shin  S.G. Cheung  N.F.Y. Tam 《Marine pollution bulletin》2014

The present study examined the relationships between soil characteristics, microbial community structure and function in the forests artificially planted with exotic Sonneratia apetala at stand ages of 1-, 2-, 7-, 10- and 14-years and Sonneratia caseolaris of 1-, 4-, 7-, 10- and 14-years in Futian National Nature Reserve, Shenzhen Bay, China. The 7-years old forests of both Sonneratia species reached peak growth and had the highest content of nitrogen and phosphorus, enzymatic activities, including dehydrogenase, cellulase, phosphatase, urease and ß-glucosidase, except arylsulphatase which increased continuously with stand ages. The microbial community structure reflected by phospholipid fatty acid (PLFA) profiles also reached the maximum value in the 7-years old forests and soil bacterial PLFAs in both forests were significantly higher than fungal PLFAs. The canonical correlation analysis revealed that differences in microbial structural variables were significantly correlated to the differences in their functional variables, and the highest correlation was found between the soil enzymatic activities and the content of carbon and nitrogen.  相似文献   

Long-term differences in annual litter production between alien (Sonneratia apetala) and native (Kandelia obovata) mangrove species in Futian,Shenzhen, China     

Lina Liu  Fenglan Li  Qiong Yang  Nora F.Y. Tam  Wenbo Liao  Qijie Zan 《Marine pollution bulletin》2014

Annual litter production in alien (Sonneratia apetala) and native (Kandelia obovata) mangrove forests in Shenzhen, China were compared from 1999 to 2010. S. apetala had significantly higher litter production than K. obovata, with mean annual total litter of 18.1 t ha⁻¹ yr⁻¹ and 15.2 t ha⁻¹ yr⁻¹, respectively. The higher litter production in S. apetala forest indicates higher productivity and consequently more nutrient supply to the estuarine ecosystems but may be more invasive due to positive plant-soil feedbacks and nutrient availability to this alien species. Two peaks were recorded in S. apetala (May and October), while only one peak was observed in K. obovata, in early spring (March and April). Leaf and reproductive materials were the main contributors to litter production (>80%) in both forests. These results suggest that the ecological function of S. apetala and its invasive potential can be better understood based on a long-term litter fall analysis.  相似文献   

自生磁铁矿与烃的富集及运移之间相互关系的研究   总被引：6，自引：2，他引：6  

刘庆生  蔡振京 《地球科学》1991,16(5):565-571

  相似文献   

白云鄂博赋矿白云岩的稀土地球化学及对稀土矿化的制约     

王凯怡张继恩  郝美珍昝景锋 胡辅佑 《地质科学》1958,55(2):439-458

东矿西缘的 A-A´剖面延伸约500 m,从下盘白云岩一直到上盘板岩为连续剖面。在白云岩与板岩接触处出现一个过渡带,其矿物组成和结构不同于白云岩和其上覆的板岩,为富含稀土,铁和萤石的条带状矿石,与主东矿的条带状矿石相似,其间还有富铁的薄的夹层。A-A´剖面的白云岩与主东矿下盘的白云岩是相似的,除其含有稍高的铁之外。推测,该剖面的白云岩来自于含大量碱金属,REE和铁的碳酸岩浆,并有高含量的挥发分。在碳酸岩浆侵位和结晶分异的过程中,这些组分会富集在残余岩浆之中,最终聚集在白云岩的顶部与板岩接触处,从而形成了该剖面过渡带中富稀土、铁、铌和萤石的条带状矿石以及富铁的薄的夹层。这些矿石类型分割开了白云岩和上覆的板岩。但是,该剖面未出现主东矿强烈而广泛的钠交代现象,即未形成钠质霓长岩。但是,该剖面的板岩中则钾钡交代广泛发育,形成了富钾和钡的板岩,可定义为钾质霓长岩。通过对A-A´剖面的系统研究及与主东矿的对比表明,白云鄂博地区的稀土、铁和微量元素的高度富集,主要出现在白云鄂博碳酸岩与围岩的接触处。但是形成一定规模的矿体还是需要具备一定的条件。首先要有来自深部规模宏大可聚集大量挥发分、稀土、铁和其它微量元素的碳酸岩（白云鄂博矿即为白云岩）,白云质碳酸岩的母岩浆分异结晶的晚期阶段在其顶部与H9板岩的接触处即在H9的底部,由于H9板岩的屏蔽作用,其下聚集了更加富集萤石,稀土和铁等的残余碳酸岩熔体形成条带状矿石,并对所接触板岩继续进行广泛而强烈的钠质交代作用即钠质霓长岩化,在这一过程中仍然发育了强烈的稀土和铁的矿化,这样即形成了超大规模的白云鄂博矿。但处于白云鄂博赋矿白云岩边缘且位置较浅的碳酸岩,钠交代作用甚微,在白云岩与板岩的接触带中虽有稀土和铁的明显富集,但不能形成具一定规模的矿体。表明,稀土的强烈矿化与钠质交代作用密切相关,而一旦钾质交代作用替代了钠质交代作用,稀土矿化明显减弱。  相似文献   

Seismological Evidence of Active Faulting in the Tendaho Rift (Afar Triangle, Ethiopia)     

S. Gresta  D. Patanè  A. Daniel  L. Zan  A. Carletti  O. Befekadu 《Pure and Applied Geophysics》1997,149(2):357-374

—A temporary network has been used to study the seismic activity in the central-northern part of the Tendaho Rift (Afar Triangle, Ethiopia). Small size earthquakes (M < 2.5) characterize the seismicity during the time interval 1993–1994 when the seismic array was operating. Shocks are mainly located in the central part of the Tendaho rift and their epicentral distribution highlights a remarkable coincidence with NW-SE trending tectonically active structures. Focal depths are confined in the range of 3–8?km. ? The few acceptable fault plane solutions suggest the occurrence of both strike-slip and dip-slip rupture mechanisms, which are often characterized by a nodal plane oriented approximately NW-SE. ?A detailed study of earthquake waveforms using polarization analysis showed the occurrence of splitting phenomena for the S waves. Despite the differences in focal mechanisms, the similarity of the faster S-wave directions (NW-SE to NNW-SSE) suggests that the direction of geological structures and/or the systems of fractures adjacent to the faults could bias shear-wave propagation. The splitting time between fast and slow shear waves shows no systematic relationship with either hypocentral distance or focal depth, suggesting that the anisotropic volume is constrained to depths shallower than 3?km.  相似文献   

试论吐鲁番—哈密盆地为剪切—背驮型盆地   总被引：1，自引：3，他引：1  

葛肖虹  王锡魁 《地质论评》1997,43(6):561-568

本文从大地构造背景，构造地貌，现今应力场，运动学特征，构造模型等５个方面论证了吐鲁番－哈密盆地的性质，认为吐－哈盆地是背驮于博格达推覆席体上的盆地，侏罗纪以来盆内的许多构造与沉积特征都取决博格达推覆构造与反冲推覆构造活动的强度。  相似文献   

用于环境研究的磁性参数简介   总被引：5，自引：0，他引：5  

曲赞 《地质科技情报》1994,13(2):98-100

根据体积磁化率，饱和等温剩磁，剩磁矫顽力，非磁滞剩磁四种主要磁性参数的特征，分别阐述了它们在环境研究中的作用及解决的问题，并介绍了近年来国外在这方面的实际应用结果。  相似文献   

Decomposition of ilmenite by concentrated KOH solution under atmospheric pressure     

Yumin Liu  Tao Qi  Jinglong Chu  Qijie Tong  Yi Zhang 《International Journal of Mineral Processing》2006

A new process was provided for decomposition of ilmenite by concentrated KOH solution under atmospheric pressure. The significant effects of reaction temperature, KOH concentration, stirring speed, particle size, and alkali-to-ilmenite mass ratios on titanium extraction were studied. The temperature and initial particle size showed significant influence on titanium extraction. The experimental data of the extraction rates under the relevant operating variables were well interpreted with the shrinking core model under chemically controlled process. The apparent activation energy of the reaction was evaluated using the Arrhenius expression. Approximately 80–85% of the titanium could be leached from the ilmenite ore under the optimal conditions.  相似文献   

海上同层侧钻井实施方案优选方法     

吴占民  王占领  王赞  龚明  杨旭才 《探矿工程》2018,45(7):41-43

为了评价同层侧钻井之裸眼水泥塞侧钻方式与套管开窗侧钻方式的经济性,优选侧钻方式,介绍了2口同层侧钻井的常规的设计及作业过程,分析弃井过程中打捞筛管工期的长短及裸眼水泥塞侧钻的经济性。通过建立应用侧钻方案决策图,筛选影响侧钻经济性的关键因素,归纳出的打捞筛管经济工期及经济临界剩余工期的计算方法,可用于在现场作业过程中出现筛管打捞困难的情况下,是否改变方案的决策,以达到节约成本之目的,具有一定的推广价值。  相似文献