989 resultados para ddc:320


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小型桡足类在生态系统中的重要作用近年来得到了广泛的关注,在近岸生态系统中,小型桡足类起着相当重要的作用。但关于小型桡足类种群动力学的研究在国内还处于起步阶段,因此我们选取了国内沿岸海域常见优势种小拟哲水蚤、双刺纺锤水蚤、太平洋纺锤水蚤及强额拟哲水蚤等四种小型桡足类为研究对象,探讨其种群动力学相关方面的变动机制。本文在2005年10月-2006年9月选取胶州湾为主要的研究海域,进行了一周年的小型桡足类的采样和培养实验研究。在胶州湾,小拟哲水蚤(Paracalanus parvus)全年出现,其种群数量变动呈现双峰型,在夏季(6月和8月)达数量高值,在冬季(1月)有一个小的高峰。种群数量在4月达全年最低值,在7月份数量也有一个明显的数量降低。从空间分布上来讲,该水蚤在冬季主要以CV期桡足幼体存在于湾南和湾外区域,湾北数量很少;从春末开始,各期幼体开始在各海区广泛分布。小拟哲水蚤在胶州湾几乎全年产卵(2月份除外),但较高的产卵率主要集中在春末到秋初,最大产卵率出现在5月,达27.9 eggs female-1d-1。总体来讲,在胶州湾小拟哲水蚤的产卵率与温度、叶绿素及体长均呈显著正相关,但与盐度呈负相关关系。从不同的区域来看,胶州湾湾北区域小拟哲水蚤产卵率较高,最高值出现在湾北6月份,产卵率达到了60.8 eggs female-1d-1。大于10 eggs female-1d-1的产卵率在湾北持续了6个月(4-9月),在湾口持续了5个月(4-8月),而在湾外只持续了3个月(5-7月)。小拟哲水蚤生物量在6月份达到最高值(6.15 mg C m-3),在4月达到全年最低值(0.028 mg C m-3)。次级生产的变动从4月到9月与生物量的变动趋势完全相似,但冬季生物量的高峰并没有伴随次级生产的高峰值,分析其原因是由于冬季低的生长率所致。小拟哲水蚤在整个胶州湾平均的年次级生产为158.41 mg C.m-3yr -1。强额拟哲水蚤(Paracalanus crassirostris)在胶州湾只在夏末到秋季出现,最大数量出现在8月份。从强额拟哲水蚤的分布区域来看,从湾内到湾外有递减趋势。在2006年9月份,只有湾北有部分种群,其他区域几乎没有该种出现。该种最大产卵率出现在8月,达11.2 eggs female-1d-1。强额拟哲水蚤生物量的变动与次级生产的变动趋势相似,最大值也都出现在8月份。该水蚤在胶州湾平均年次级生产仅为2.12 mg C m-3yr-1。双刺纺锤水蚤(Acartia bifilosa)在胶州湾是全年出现,其种群数量在5-6月份突发性增加达全年最高值(>8000 ind. m-3),之后又急剧下降。从该种的区域分布来看,5-6月份数量的高峰主要出现在湾北区域,7月份虽然各区域数量均下降,但大部分种群集中在湾外区域。双刺纺锤水蚤在胶州湾几乎全年产卵(1-2月除外),产卵率的最高值出现在4月,达16.5 eggs female-1d-1。4月份雌体高的产卵率为5月份种群数量的大量增加提供了补充。双刺纺锤水蚤生物量与次级生产的变动趋势一致,在5-6月份达到高值,在秋冬季次级生产较低。双刺纺锤水蚤在整个胶州湾平均的年次级生产为114.61 mg C m-3yr-1。太平洋纺锤水蚤(Acartia pacifica)在胶州湾季节性出现,在冬春季节消失,从夏季开始出现。该种在5月零星出现,种群数量在6月份开始增多,到7月份达到最高值2356 ind. m-3,之后在8月数量锐减至196 ind. m-3。从区域分布来看,该水蚤在胶州湾只出现在湾北和湾南区域,湾外区域几乎没有,而且呈现湾北到湾南递减的趋势。6月份数量大部分出现在湾北区域,到7月份才有一部份在湾南出现。太平洋纺锤水蚤在其出现季节均产卵,最大产卵率出现在6月份,达37.17 eggs female-1 d-1,部分补充了7月份太平洋纺锤水蚤种群数量的大量增加。太平洋纺锤水蚤生物量与次级生产的变动趋势相似,在7月份达到了最高值,在11月达到最低值。太平洋纺锤水蚤在胶州湾平均的年次级生产为45.63 mg C m-3yr-1。胶州湾四种小型桡足类总的年次级生产为~320 mg C m-3 yr-1。

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本研究论文属于国家科学基金重点研究项目“东海关键海洋通量过程的研究”计划的一个组成部分,通过1998年夏季东海航次,测定了颗粒有机碳的(Particulate Organic Carbon)含量,并研究了东海夏季POC含量的分布特点以及影响因素。同时,通过模式计算了部分站位的POC的垂直表观通量。然后,根据海水悬浮物质、底质物和浮游生物中的DOC的含量,定量的研究了东海的再悬浮现象,计算得到32°N断面和PN断面部分站位的再悬浮比,并计算得到了这些站位的POC净垂直通量,使我们对东海的POC净沉积通量有了一个定量的认识和把握。通过研究,我们发现东海夏季的POC的分布特点是:(1)近岸区域有明显的高值区的存在,并随离岸距离的增加而降低,这主要是受长江径流的影响;(2)在以(32°N, 125°E-125.5°E)为中心的冷涡表层海域存在着另一个POC含量的高值区,随深度增加而降低,在25米层以下随深度的增加而增加,在近底层形成一个新的高值区,研究表明表层高值区主要受生物生长的控制,而底层的高值区的存在与该区域的涡动层或上升流的存在有一定的关系;(3)同时,在东海所研究的两个断面,TSM(Total Suspended Materials)和POC的含量之间表现出了较好的相关性。通过模式研究,计算了六个站位八个层次的POC的垂直通量,其垂直通量为12.43 mg·m~(-2)·d~(-1)-148.23 mg·m~(-2)·d~(-1),最大值为148.23 mg·m~(-2)·d~(-1),出现在107站(32°N, 125°E)10米层,最小值为12.43 mg·m~(-2)·d~(-1),出现在111站(32°0.08N, 125°59.57'E)的底层。通过对东海再悬浮比率的定量研究,计算了五个站和个层次的再悬浮比率。结果表明:(1)表层海水中悬浮物质的再悬浮比率在47.4%-79.18%之间;底层的再悬浮比率在72.75%-96.96%之间;(2)再悬浮比率的最大值出现在106站(32°N, 124°30'E)的底层,而再悬浮比率的最小值出现在102站(32°N, 122°30'E)的表层。在POC重直通量和再悬浮模式计算的基础上,我们计算得到了六个站位八个层次的POC净垂直通量,颗粒有机碳的净垂直通量最大值出现在107站(32°N, 125°E)的10米层,为117.4 mg·m~(-2)·day~(-1);最小值出现在111站(32°0.08'N, 125°59.57'E)的底层为0.79 mg·m~(-2)·day~(-1)。通过几个站位的模式计算估算了东海颗粒有机碳平均的净沉积通量,其大约为6.55 mgC·m~(-2)·day~(-1),即2.39gC·m~(-2)·y~(-1)。从而使我们对东海的颗粒有机碳的净垂直通量有了一个定量的认识。

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本文通过胶州湾围隔实验、微藻培养实验研究了海洋微藻产生溶解有机物的三维荧光特性,并初步利用经验正交函数对三维荧光光谱图进行了主成分分析,通过东海取样研究了东海荧光溶解有机物的时空分布特征,并对荧光溶解有机物的来源进行了分析。得到了一些初步结论: 胶州湾围隔实验中不同营养盐培养结果表明浮游植物可产生类蛋白和类腐殖质荧光,类蛋白荧光峰由类酪氨酸(tyrosine-like)荧光峰和类色氨酸(tryptophan-like)荧光峰组成,主要位置为Exmax/Emmax=270nm/290~310nm,Exmax/Emmax= 270~290/320~350的荧光峰强度比较弱;在Exmax/Emmax=250~260/380~480nm(A峰)、Exmax/Emmax=310~320/380~420nm(C峰)和Exmax/Emmax=330~350/420~480nm(M峰)位置均出现零散的类腐殖质荧光峰,其中以A峰为主。类酪氨酸荧光强度明显高于类腐殖质荧光强度。浮游植物量降低时,类酪氨酸荧光强度与叶绿素a浓度呈明显的负相关。硅藻和甲藻产生的类酪氨酸和类色氨酸荧光强度之间具有较好的相关性,两者来源相似, 并且甲藻与硅藻相比能够产生更多的类蛋白荧光物质。不同环境下类腐殖质混合物的组分比例不同,甲藻生长环境下相对于硅藻具有较低的A:C比值。 在实验室培养中肋骨条藻(Skeletonema costatum)、塔玛亚历山大藻(Alexandrium tamarense)、微小亚历山大藻(Alexandrium mimutum)、锥状斯氏藻(Scrippsiella trochoidea)、东海原甲藻(Prorocentrum donghaiense)及海洋原甲藻(Prorocentrum micans)的实验结果表明,微藻在生长过程中产生出荧光溶解有机物,中肋骨条藻为代表的硅藻主要产生类腐殖质荧光物质,而甲藻在指数增长期主要产生类蛋白荧光物质。进入消亡期后类蛋白荧光和类腐殖质荧光强度迅速增大,原因可能是衰老、死亡藻细胞的破碎释放出大量的荧光有机物质所致,此外还有细菌对非荧光有机物进一步降解。塔玛亚历山大藻、微小亚历山大藻、东海原甲藻及海洋原甲藻的类蛋白荧光强度在消亡后期由于细菌降解或光降解等因素而降低。同属微藻产生的荧光物质相似,例如塔玛亚历山大藻与微小亚历山藻、东海原甲藻与海洋原甲藻,但具体荧光峰位置有所不同。利用经验正交函数能够对三维荧光光谱谱图进行主成份分析。 在利用三维荧光光谱法研究长江口海域台风前后不同站位荧光溶解有机物荧光特性及分布特征的结果表明,长江口海区主要的荧光溶解有机物荧光峰为T峰、S峰和A峰。风前和风后的类色氨酸分别来源于相似物质。风前,在表层浮游植物能够产生类蛋白荧光物质,而底层类蛋白荧光物质不受浮游植物的影响,长江冲淡水能够带来部分类蛋白荧光物质;表层的类腐殖质不受浮游植物的影响,而底层的浮游植物在降解过程中能够产生一部分类腐殖质,并且长江冲淡水对表层和底层的类腐殖质来源均有很大贡献。风后,表层的类色氨酸与叶绿素a浓度不呈相关性,而底层却呈正相关,另外表层和底层的类色氨酸均受到长江冲淡水的影响;表层和底层的类腐殖质与叶绿素a均没有相关性,但受陆源影响显著,长江冲淡水能带来类腐殖质。

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Sea water samples were collected in the East China Sea in March and April, 2005, and three-dimensional fluorescence of dissolved organic matter was measured by fluorescence excitation-emission matrix spectroscopy. The position, number and intensity of fluorescence peak in the spectra and the relations of the peaks were analyzed to determine the type, distribution and origin of the fluorescence dissolved organic matter. Seven types of fluorescence peaks were detected from the samples. There are protein-like fluorescence peaks B with Ex(max)/Em(max) = 275/300 nm, D with Ex(max)/Em(max) = 225/295-305 nm, T with Ex(max)/Em(max) = 280/345 nm, and S with Ex(max)/Em(max) = 225-240/320-350 nm, two humic-like peaks A with Ex(max)/Em(max) = 250-255/410-455 nm and C 335-345/410-440 ran, and marine humic peak M with Ex(max)/Em(max) = 305 nm/400-420 nm. Peaks B, S and A appeared in all surveyed area. Peaks T and D appeared in the north of the surveyed area. Peaks M and C only appeared in a few stations. In the surface layer, the source of the fluorescence dissolved organic matter might be the fresh water outflow of the Yangtze River, while the fluorescence dissolved organic matter in the middle layer had double sources from the Yangtze River and the phytoplankton. The good correlationships of different fluorescence peaks showed the same source or some relationship between the protein-like and the humic-like fluorescence dissolved organic matter.

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Fluorescence excitation-emission spectroscopy (EEMS) was employed to analyze the 3-dimensional fluorescence of dissolved organic matter in the East China Sea after diatom red tide dispersion. The relationships between fluorescence peak intensity, and salinity and chlorophyll-a were discussed. The centers of protein-like fluorescence peaks dispersed at Ex(max)/Em(max) = 270-280/290-315 nm (Peak B), 220-230/290-305 nm (Peak D), 230-240/335-350 nm(Peak S)and 280/320 nm(Peak T). Two humic-like peaks appeared at 255-270/435-480 nm (Peak A) and 330-350/420-480 nm(Peak C). High tyrosine-like intensity was observed in diatom red tide dispersion area, and tryptophan-like fluorescence was also found which was lower. High FIB/FIS showed that diatom red tide produced much tyrosine-like matter during dispersion. Peaks S, A and C had positive correlation with one another, and their distributions were similar, which decreased with distance increasing away from the shore. Good negative correlations between peaks S, A and C and salinity suggested that Jiangsu-Zhejiang coastal water was the same source of then-L Correlations between fluorescence peak intensity and chlorophyll-a were not remarkable enough to clear the relationship between fluorescence and living algal matter. It was supposed that the living algal matter contributed little to the fluorescence intensity of algal dispersion seawater.

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Chitosan and carboxymethl-chitosan (CM-chitosan) membranes with different molecular mass were prepared by a casting method. The cytocompatibility of two kinds of polysaccharide membranes to skin fibroblasts that cultured in vitro were studied. The methods were to culture the cells in soaking fluid of membranes and to culture the cells on the membranes directly. The results showed that the soaking fluid had no toxicity to fibroblasts and the biological security of lower molecular mass membranes were better than higher molecular mass membranes, and CM-chitosan membranes were better than chitosan membranes. In addition, the growth of fibroblasts on chitosan membranes was inhibited and the cells would fall off from chitosan membranes after a period of culture. However, the cells adhered and expanded well on CM-chitosan membranes. All these demonstrated that cytocompatibility of CM-chitosan membranes to skin fibroblasts was better than chitosan membranes.

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A shellfish toxin investigation along the Chinese coast has recently been conducted using both HPLC and mouse assay methods. The results showed that DSP was widely distributed in different shellfish species in China. 26 out of 89 samples had DTX1 (dinophysistoxin-1) or OA (okadaic acid) but the DSP content in most shellfish samples did not reach the regulatory limit for human consumption adopted in many countries (20 mu g/100 g soft tissue). PSP was also found in 5 out of 96 samples along the coast. One sample, Chlamys nobilis from Hong Kong contained high levels of PSP (320 mu g STX equivalent/100 g soft tissue), compared to the regulatory limit (80 mu g STX equivalent/100 g soft tissue). After the recent outbreak of red tide in Hong Kong waters, three further shellfish samples were collected within 40 days to investigate the impacts of this event, It was shown that high levels of PSP continued to exist in Hong Kong waters. This report provides the first report of DSP and PSP distribution along the Chinese coast. (C) 1999 Elsevier Science Ltd, All rights reserved.

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Paraprionospio pinnata (Ehlers, 1901), a poorly known and potentially cosmopolitan polychaete, was examined from museum specimens and from collections in Jiaozhou Bay, the Yellow Sea. New observations indicate that previous Chinese records of P. pinnata are doubtful, and that Chinese waters contain at least three valid species of Paraprionospio, two are known and one is new. Paraprionospio inaequibranchia (Caullery, 1914) and Paraprionospio coora Wilson, 1990, previously misidentified as P. pinnata, are reported from Chinese waters for the first time. Paraprionospio crist'ata. new species, is characterized by having brown pigment patches on the prostomium, ventral crests on chaetigers 9 and 10, dorsal crests on the middle part of the body (from chaetigers 21-23, not beyond chaetiger 29). thin filaments on chaetiger 3, and bifoliate branchial lamellae.

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Novel microbiocides 2-(hydroxymethyl)benzo[d)isothiazol-3(2H)-one (7) and (3-oxobenzo[d]isothiazol-2(3H)-yl)methyl benzencarboxylates (11a-c) were synthesized in good yields, and their structures were characterized by means of H-1 NMR, MS, and elemental analysis. The new compounds were tested preliminarily in laboratory assays against the aquicolous bacteria including Escherichia coli, Staphyloccus aurueus, Vibrio alginolyticus, Aeromonas hydrophila, and Bacillus subtilis. The results show all the synthesized compounds have good antimicrobial activity. The antimicrobial activity of all the tested compounds against all test bacteria is >96.6% at the concentration of 10(-2) mg mL(-1). These compounds can be further developed for effective microbiocides in the future.

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利用5-9月植物生长期间所观测的不同植被盖度条件下土壤温、湿度资料,分析了矮嵩草草甸植被盖度对土壤温、湿度的影响.结果表明:有植被覆盖区随季节进程,植被盖度增加,土壤温度升高,湿度下降;8:00-19:00土壤温度随植被盖度的增加而增加,14:00土壤温度随植被盖度增加而降低;不论是早晚还是中午,土壤湿度都随植被盖度的增加而增加.

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通过对不同类型草地生产力与物种特征(重要值)、均匀度之间的关系研究,结果表明:群落物种特征(重要值)与生产力之间呈极显著的线性关系;物种均匀度与生产力之间呈负线性关系,但差异不显著。在自然生态系统中,由于物种间的相互作用(资源的竞争利用),物种数目在不同类型草地群落的物种组成上的不均匀分布,导致不同生境条件下均匀度的异同。

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为研究根田鼠(Microtus oeconomus)对不同类型栖息地的利用强度,于2002-2003年的7-9月在中国科学院海北高寒草甸生态系统定位站地区采用样方法测定了4种类型栖息地(人工耕作地、真草甸、沼泽化草甸、金露梅灌丛)中的3个根田鼠活动强度变量(跑道长度、跑道分叉数、洞口数).除了跑道长度和跑道分叉数在真草甸和沼泽化草甸间差异不显著外,3活动强度变量在不同类型栖息地间均差异显著,而且变化趋势一致;根田鼠对4类栖息地的利用强度从大到小依次为金露梅灌丛、沼泽化草甸、真草甸、人工耕作地.整体上根田鼠表现为偏好利用食物资源丰富、没有竞争性啮齿类栖息、较为郁闭的栖息地.

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根田鼠(Micortus oeconomus)是一种分布广泛的小型哺乳动物,在海北高寒草甸地区,根田鼠是优势小型啮齿动物之一,主要分布于植被较好的草甸和灌丛中,有关其自然以及实验状态下种群数量动态的研究相对较多,但是对该地区冬季恶劣自然条件下,其种群动态的研究尚未见报道。研究冬季根田鼠种群特征的变化有助于对其整个生活史过程的全面理解,也便于了解冬降劣气候条件对其越冬留存率的影响进而又是如何影响翌年的种群数量。

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采用CI-301PS红外CO2分析仪,测定了退化草地暗沃寒冻雏形土CO2排放速率。研究结果表明:(1)CO2排放速率具有明显的日变化,日最大排放速率在12:00~14:00时出现,最低值出现于凌晨4:00~8:00。白天大于夜晚。(2)植物生长季,CO2释放速率有明显的季节变化和物候变化,日平均释放速率为(320.86±130.49)mg/ m2·h,CO2释放速率的物候变异为草盛期>草枯黄期>草返青期。(3)CO2释放速率的日变化进程主要受气温和地表温度制约,而季节动态与气温及0~30cm地温均呈极显著正相关关系。(4)退化草地上CO2释放速率较低。

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There is a need for methodology to warm open-field plots in order to study the likely effects of global warming on ecosystems in the future. Herein, we describe the development of arrays of more powerful and efficient infrared heaters with ceramic heating elements. By tilting the heaters at 45 degrees from horizontal and combining six of them in a hexagonal array, good uniformity of warming was achieved across 3-m-diameter plots. Moreover, there do not appear to be obstacles (other than financial) to scaling to larger plots. The efficiency [eta(h) (%); thermal radiation out per electrical energy in] of these heaters was higher than that of the heaters used in most previous infrared heater experiments and can be described by: eta(h) = 10 + 25exp(-0.17 u), where u is wind speed at 2 m height (m s(-1)). Graphs are presented to estimate operating costs from degrees of warming, two types of plant canopy, and site windiness. Four such arrays were deployed over plots of grass at Haibei, Qinghai, China and another at Cheyenne, Wyoming, USA, along with corresponding reference plots with dummy heaters. Proportional integral derivative systems with infrared thermometers to sense canopy temperatures of the heated and reference plots were used to control the heater outputs. Over month-long periods at both sites, about 75% of canopy temperature observations were within 0.5 degrees C of the set-point temperature differences between heated and reference plots. Electrical power consumption per 3-m-diameter plot averaged 58 and 80 kW h day(-1) for Haibei and Cheyenne, respectively. However, the desired temperature differences were set lower at Haibei (1.2 degrees C daytime, 1.7 degrees C night) than Cheyenne (1.5 degrees C daytime, 3.0 degrees C night), and Cheyenne is a windier site. Thus, we conclude that these hexagonal arrays of ceramic infrared heaters can be a successful temperature free-air-controlled enhancement (T-FACE) system for warming ecosystem field plots.