EFFECTS OF LAND USE CHANGES ON THE CARBON STORAGE OF TERRESTRIAL ECOSYSTEM——A CASE STUDY OF HULUN LAKE AND TAIHU LAKE BASINS

土地利用和覆被变化对陆地生态系统碳循环有着显著的影响,研究土地利用变化对陆地生态系统碳储量的影响,有利于揭示人类活动和气候变化对陆地生态系统碳循环的驱动机制,同时为制定合理的区域碳排放政策提供参考.本研究采用1980年、1995年、2000年和2005年4期遥感影像解译的土地利用数据,借助IPCC第四次报告推荐的计算方法和对应参数,选择我国东部亚热带和温带的两个典型大湖——太湖流域和呼伦湖流域1980～2005年碳收支情况进行估算,结果表明:1)1980～2005年太湖流域的土地利用结构变化主要表现为农田的逐年减少和聚居地的持续增长,而呼伦湖流域则主要表现为由于林地向草地的转化和草地向其他土地的转化所导致的林地面积的减少和其他土地面积的增加.2)在碳源/汇方面,太湖流域和呼伦湖流域均表现为碳汇,对于太湖流域来说,林地和农田是主要的碳汇,聚居地是碳支出的主要贡献者,2000年以来呼伦湖流域固碳能力出现比较明显的下降,林地和草地的变化是导致碳储量变化的主导因素.3)通过两个流域碳储量变化情况的比较,发现人类活动对陆地生态系统碳储量的影响较为显著;此外,植被类型差异以及成林时间也是影响固碳能力的主要原因.     

新时期中华民族精神的培育

民族精神是一个民族赖以生存和发展的精神支撑。建设中国特色的社会主义现代化事业是一项前无古人的伟大创举 ,它更加需要一种积极向上的民族精神的支撑。培育新时期的中华民族精神是我们的一项重要任务 ,在培育民族精神的时候应该继承民族文化的优秀传统 ,吸收其他民族文化的优秀成分 ,同时又要使民族精神保持与时俱进 ,不断丰富和发展     

Comparison among sea surface roughness schemes

1 INTRODUCTIONIt is well known that wind-generated wavestorm surge and atmospheric circulation as impor-tant ocean weather events are closely related tomomentum exchange between sea and atmosphere(Oncley and Dudhia, 1995). For this reason, in thepast 20 years, attention has been directed towardshow to better describe momentum exchange throughsea surface. In general, to precisely determine theexchange, improvement should be made in the as-pects of reasonably depicting the roughness de-pend…     

SMW搅拌桩在临近地铁基坑工程中的应用

介绍了SMW搅拌桩在上海嘉和大厦基坑工程中的应用,以相关的施工过程控制措施使其在施工中对地铁盾构的变形影响达到最小,证明了该法对同类型复杂工程的适应性.     

合成孔径雷达对地观测应用中目标感兴趣区域的自动获取

在简要评述国内外对地观测应用中,利用SAR图像进行目标ROI的自动获取方面的研究成果及存在问题的基础上,提出了一种SAR图像目标ROI自动获取新方案,包括SAR图像自动目标检测方案和SAR图像自动目标鉴别方案并解决其中的关键技术。实测数据的实验结果证明了新方案具有稳健性强、适用性广、自动化程度高、计算量小、工程实现易等特点,说明了该方案对于空间对地观测具有广泛的应用前景。     

基于GPS的“雪龙”船冲击式破冰模式识别研究

"雪龙"号破冰船是我国目前唯一的极地考察船,破冰航行是极地船舶的重要特征之一。以"雪龙"号破冰船的GPS数据为基础,通过建立模型算法识别冲击式破冰这一特殊的航行状态,在整个中国第28次南极考察航次的数据分析中,整体识别率超过86.1%,识别正确率达到98%以上。利用此算法,在中国第27次南极考察航次的破冰识别率也超过85%,识别正确率达到93.5%。雪龙船两个航次实测GPS数据验证了本文算法的可用性,而破冰识别统计结果表明,不同航次的破冰模式具有较大的差异。     

Dietary Analysis of Marine Fish Species: Enhancing the Detection of Prey-Specific DNA Sequences via High-Throughput Sequencing Using Blocking Primers

Dietary studies of fish can enhance our understanding of predator-prey interactions and provide important insights into complex marine food webs. In this study, we performed dietary analyses of three commercially important fish species in South China: Acanthopagrus latus, Pampus argenteus, and Scomberomorus commerson. Two distinct fragments of the mitochondrial cytochrome c oxidase I (mtCOI) gene, a small (130 bp) and large (300 bp) amplicon, were amplified from the DNA extracted from the gut contents in the presence of blocking primers designed to inhibit the amplification of predator-specific DNA. The amplicons from each predator species were tagged with a unique indexing bar code and sequenced using the Illumina MiSeq platform. Our results showed that the three fish species consumed a wide variety of prey, including jellyfish, copepods, crustaceans, and fish. Seasonal variations in prey composition and species-selective predation were observed. Our approach of combining next-generation sequencing with blocking primers greatly enhanced the speed and resolution of the dietary analyses in marine fishes and could provide novel insights into marine ecosystems.     

Intra- and inter-specific variability in total and methylmercury bioaccumulation by eight marine fish species from the Azores

We relate fish biological and ecological characteristics to total and organic mercury concentrations to determine whether accumulation is influenced by trophic level, Hg concentration in the diet, and vertical distribution. Levels of total mercury and methylmercury were determined in the muscle tissue of eight species of fish: Pagellus acarne, Trachurus picturatus, Phycis phycis, P. blennoides, Polyprion americanus, Conger conger, Lepidopus caudatus and Mora moro, caught in the Azores. All such fishes are commercially valuable and were selected to include species from a wide range of vertical distributions from epipelagic (<200 m) to mesopelagic (>300 m) environments. Methylmercury was the major form accumulated in all species, comprising an average of 88.1% of total mercury. Concentrations of mercury (total and methylmercury) increased with age, length and weight. Based on data from other studies, mercury concentrations in fish diet were estimated. Mercury levels in food ranged from 0.08 to 0.32 ppm, dry weight. Hg concentrations in the food and in muscle tissue from different species were positively correlated. Total Hg levels in the muscles were approximately nine times those estimated in food. Total mercury concentrations in muscle were positively correlated with both trophic level and median depth. Such enhanced mercury bioaccumulation in relation to depth appears to be determined primarily by concentrations in food and ultimately by water chemistry, which controls mercury speciation and uptake at the base of the food chain.