牙鲆饲喂湿颗粒饲料的应用研究   总被引：4，自引：2，他引：4  

陈四清  于东祥  马爱军  张少华  宋宗诚 《海洋科学》2002,26(7):59-61

采用0,10% ,20% ,40%和60 %比例的全价粉末饲料与冰鲜杂鱼混合 ,配制成湿颗粒饲料 ,投喂牙鲆(Paralichthysolivaceus,T.&S.) ,进行工厂化养殖试验。结果证明随着添加全价粉末饲料量的增加 ,饲料系数逐渐降低 ,鱼体增重率逐渐增加 ,在鱼体防病、成活率、体色方面 ,投喂添加粉末饲料的湿颗粒饲料都明显优于单一的冰鲜杂鱼 ,其中 ,4号饲料在养殖成本方面 ,每公斤鱼的饲料投入比鲜杂鱼节省1.26元  相似文献   

珠江口海岛及海域地质环境与灾害初探   总被引：4，自引：0，他引：4  

詹文欢  孙宗勋  朱俊江  唐诚  丘学林 《海洋地质与第四纪地质》2001,21(4):31-36

珠江口海岛及其邻近海域是华南沿海地质灾害类型较齐全的地区之一，主要有活动断裂、地震、地裂缝、软土、风沙、滑坡、崩塌、地面沉降和海平面上升等。珠江口海岸主要发育弱活动和微活动断裂，活动断裂和断块构造的运动和调整是产生地震活动的主要因素。海平面上升已成为当今世界关注的环境恶化和未来50a内产生严重威胁的灾害。风沙作用和软土地基主要分布于珠江口海岛海岸带及近岸岛屿。本区的地质灾害以内动力类型为主。  相似文献   

东寨港红树林区大型底栖动物生态与滩涂养殖容量的研究 I.潮间带表层底栖动物数量的初步研究   总被引：8，自引：0，他引：8  

黄勃  张本  陆健健  欧宗东  邢增祥 《海洋科学》2002,26(3):65-68

于2000年1-3月，对东寨港红树林区潮间带表层大型底栖动物进行调查，初步分析了东寨港红树林区潮间带表层大型底栖动物的生物量，密度等生态特点，研究结果表明，东寨港红树林区潮间带表层大型底栖动物平均生物量为120.38g/m^2，栖息密度为80.53个/m^2，以期为合理开发与保护东寨港红树林区底栖生物资源提供科学依据。  相似文献   

长白山苔原带优势植物种的分布格局及其关联性研究     

靳英华  许嘉巍  刘丽娜  贺红士  陶岩  宗盛伟  杜海波  王雷  朱瑞帅 《地理科学》2016,36(8):1212-1218

通过开展植被样方调查,确定苔原带的主要优势种,分析优势种的分布格局及其关联性,从地理角度分析长白山苔原带植被变化特征。研究表明：① 长白山苔原带8个优势种中,草本植物已占6个。灌木中牛皮杜鹃（Rhododendron chrysanthum）依然为最主要的优势种,但笃斯越橘（Vaccinium uliginosum）的优势地位已被草本的小白花地榆（Sanguisorba parviflora）取代。草本植物聚集程度强,苔原植被存在草甸化趋势。② 除牛皮杜鹃与大白花地榆（Sanguisorba stipulata）之间存在较显著的负联结,排它现象明显外,多种优势种之间存在正联结,有弱的伴生现象,牛皮杜鹃和小白花地榆为强正联结,伴生现象更明显,草本植物与灌木伴生将长期存在。③ 各草本植物入侵、定植、扩展机制多样。小白花地榆分布广,聚集程度较弱,以种子繁殖为主,扩展速度较快;大白花地榆、小叶章（Calamagrostis angustifolia）等聚集程度较强,以无性繁殖为主,扩展速度较慢,但竞争能力强,在适宜生境中,能驱除其它物种。  相似文献   

Effective seed distribution pattern of an upward shift species in alpine tundra of Changbai Mountains     

Shengwei Zong  Jiawei Xu  Eckart Dege  Zhengfang Wu  Hongshi He 《中国地理科学(英文版)》2016,26(1):48-58

The vegetation of alpine tundra in the Changbai Mountains has experienced great changes in recent decades. Narrowleaf small reed(Deyeuxia angustifolia), a perennial herb from the birch forest zone had crossed the tree line and invaded into the alpine tundra zone. To reveal the driven mechanism of D. angustifolia invasion, there is an urgent need to figure out the effective seed distribution pattern, which could tell us where the potential risk regions are and help us to interpret the invasion process. In this study, we focus on the locations of the seeds in the soil layer and mean to characterize the effective seed distribution pattern of D. angustifolia. The relationship between the environmental variables and the effective seed distribution pattern was also assessed by redundancy analysis. Results showed that seeds of D. angustifolia spread in the alpine tundra with a considerable number(mean value of 322 per m2). They were mainly distributed in the low elevation areas with no significant differences in different slope positions. Effective seed number(ESN) occurrences of D. angustifolia were different in various plant communities. Plant communities with lower canopy cover tended to have more seeds of D. angustifolia. Our research indicated reliable quantitative information on the extent to which habitats are susceptible to invasion.  相似文献   

Geochemistry and magmatic history of eclogites and ultramafic rocks from the Chinese continental scientific drill hole: Subduction and ultrahigh-pressure metamorphism of lower crustal cumulates     

Yongsheng Liu  Keqing Zong  Peter B. Kelemen  Shan Gao 《Chemical Geology》2008,247(1-2):133-153

Three distinct groups of eclogites (low-Mg–Ti eclogites, high-Ti eclogites and Mg-rich eclogites) and ultramafic rocks from the depth interval of 100–680 m of the Chinese Continental Scientific Drill Hole were studied. The low Mg#s (= 100^?molar Mg/(Mg + Fe)) (81–84%) and low Ni (1150–1220 ppm) and high Fe₂O₃^total (13–15 wt.%) contents of ultramafic rocks suggest a cumulate origin. Mg-rich eclogites show middle and heavy REE enrichments, which could not be produced by metamorphic growth of garnet. Instead, if the rocks formed from a light REE enriched magma, there may be an igneous precursor for some garnets in their protolith. Alternatively, perhaps they formed from a light REE depleted magma without garnet. The high-Ti eclogites are characterized by unusually high Fe₂O₃^total contents (up to 24.5 wt.%) and decoupling of high TiO₂ from low Nb and Ta contents. These features cannot be produced by concentration of rutile during UHP metamorphism (even for samples with TiO₂ > 4 wt.%) of high-Ti basalts, but could be attributed to crystal fractionation of titanomagnetite (for those with TiO₂ < ～ 4 wt.%) or titanomagnetite + ilmenite (for those with TiO₂ > ～ 4 wt.%). Thus, we suggest that protoliths of the high-Ti eclogites were titanomagnetite/ilmenite-rich gabbroic cumulates. As a whole, the low-Mg–Ti eclogites are geochemically complementary to the high-Ti eclogites, Mg-rich eclogites and ultramafic rocks, and could be metamorphic products of gabbroic/dioritic cumulates formed by high degree crystal fractionation. All these observations suggest that parental materials of the ultramafic rock-eclogite assemblage could represent a complete sequence of fractional crystallization of tholeiitic or picritic magmas at intermediate to high pressure, which were later carried to ultrahigh-pressure conditions during a continental collision event.  相似文献   

Comparative analysis of the extreme temperature event change over Northeast China and Hokkaido,Japan from 1951 to 2011   总被引：1，自引：1，他引：0  

Lei Wang  Zhengfang Wu  Fuxue Wang  Haibo Du  Shengwei Zong 《Theoretical and Applied Climatology》2016,124(1-2):375-384

  相似文献   

区域气候模式对温室效应引起的中国西北地区气候变化的数值模拟   总被引：23，自引：4，他引：19  

高学杰  赵宗慈  丁一汇 《冰川冻土》2003,25(2):165-169

使用RegCM2区域气候模式,进行了CO₂加倍对中国区域气候影响的数值试验,对西北地区进行了重点分析.结果表明,在CO₂加倍的情况下,西北地区的气温将明显升高,年平均升高值为2.7℃,高于全国平均变化.同时降水也将明显增加,平均增加率达到25%,远高于全国平均,增加率的数值大小依次为冬季、春季、秋季和夏季.  相似文献   

Holocene and Lateglacial relative sea‐level change in north‐west England: implications for glacial isostatic adjustment models     

Jeremy M. Lloyd  Yongqiang Zong  Paul Fish  James B. Innes 《第四纪科学杂志》2013,28(1):59-70

Relative sea‐level (RSL) change is reconstructed for central Cumbria, UK, based on litho‐ and biostratigraphical analysis from the Lateglacial to the late Holocene. The RSL curve is constrained using ten new radiocarbon‐dated sea‐level index points in addition to published data. The sea‐level curve identifies a clear Lateglacial sea‐level highstand approximately 2.3 m OD at c. 15–17 k cal a BP followed by rapid RSL fall to below ?5 m OD. RSL then rose rapidly during the early Holocene culminating in a mid‐Holocene highstand of approximately 1 m OD at c. 6 k cal a BP followed by gradual fall to the present level. These new data provide an important test for the RSL predictions from glacial isostatic adjustment models, particularly for the Lateglacial where there are very little data from the UK. The new RSL curve shows similar broad‐scale trends in RSL movement predicted by the models. However, the more recent models fail to predict the Lateglacial sea level highstand above present reconstructed by the new data presented here. Future updates to the models are needed to reduce this mismatch. This study highlights the importance for further RSL data to constrain Lateglacial sea level from sites in northern Britain. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Quantitative relationships between precipitation and temperature over Northeast China, 1961–2010     

Haibo Du  Zhengfang Wu  Yinghua Jin  Shengwei Zong  Xiangjun Meng 《Theoretical and Applied Climatology》2013,113(3-4):659-670

This paper investigates monthly and seasonal precipitation–temperature relationships (PTRs) over Northeast China using a method proposed in this study. The PTRs are influenced by clouds, latent and sensible heat conversion, precipitation type, etc. In summer, the influences of these factors on temperature decrease are different for various altitudes, latitudes, longitudes, and climate types. Stronger negative PTRs ranging from ?0.049 to ?0.075 °C/mm mostly occur in the semi-arid region, where the cold frontal-type precipitation dominates. In contrast, weaker negative PTRs ranging from ?0.004 to ?0.014 °C/mm mainly distribute in Liaoning Province, where rain is mainly orographic rain controlled by the warm and humid air of East Asian summer monsoon. In winter, surface temperature increases owing to the release of latent heat and sensible heat when precipitation occurs. The stronger positive PTRs ranging from 0.963 to 3.786 °C/mm mostly occur at high altitudes and latitudes due to more release of sensible heat. The enhanced atmospheric counter radiation by clouds is the major factor affecting increases of surface temperature in winter and decreases of surface temperature in summer when precipitation occurs.  相似文献