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11.
Spatial and seasonal variations in depth profile of trace metals in saltmarsh sediments from Sapelo Island, Georgia, USA 总被引:1,自引:0,他引:1
This study was undertaken to elucidate the impact of early diagenetic processes on the accumulation of trace metals in Sapelo Island saltmarsh sediments as a function of time, space and sediment properties. Samples were collected from three sites in summer (May 1997) and winter (January 1998) along a transect from an unvegetated Creek Bank through a vegetated Tidal Levee to the vegetated midmarsh with evident lateral heterogeneity caused by hydrologic regime, macrophytes and microbial and macrofaunal activities. A suite of trace metals (As, Ba, Cr, Co, Cu, Cd, Mo, Ni, Pb, Th, Ti, U, V, Zn and Zr) was analyzed to obtain their depth-distribution at the three sites. Spatially marked differences were observed, that were primarily related to hydraulic flushing of trace metals away from the sites in high-energy regimes, rapid downward mixing and reworking of sediment via bioturbation, and below-ground degradation and production of Spartina biomass. Although sulfate reduction and the formation of acid volatile sulfide and pyrite were dominant processes throughout the marsh, the trace metal scavenging role of sulfides was not apparent. However, possible sulfurization of organic matter, leading to enhanced trapping of trace metals with organic carbon, may have played an important role in sequestration of trace metals.No similarity was observed visually between the depth trends of trace metals and sediment properties (grain size, iron-oxyhydroxide content, acid volatile sulfides and pyrite content) that are known to play a major role in trace metal partitioning. Only organic carbon content closely followed the trace metal profiles at all the three sites. Minor variation in depth-integrated sediment trace metal content was observed seasonally at each of the three sites. Furthermore, the depth trend of profiles of individual trace metals also did not vary significantly over the seasons either. 相似文献
12.
Analysis, synthesis and modelling of high-resolution observations of salt-marsh eco-geomorphological patterns in the Venice lagoon 总被引:1,自引:0,他引:1
Marco Marani Enrica Belluco Sergio Ferrari Sonia Silvestri Andrea D'Alpaos Stefano Lanzoni Alessandra Feola Andrea Rinaldo 《Estuarine, Coastal and Shelf Science》2006,69(3-4):414
The present paper describes observations, analyses and models of salt-marsh channel network and vegetation patterns with the aim of contributing to the development of predictive models of ecological and morphological co-evolution. Existing and new observations are described, with particular emphasis on remote sensing and ancillary field surveys, which are shown to allow reliable, accurate and repeatable quantitative characterizations of landform and vegetation properties over the spatial scales of interest. The observed channel network morphological characters are then used as the basis and validation of models describing the emergence of channel network and vegetation spatial patterns. In particular, with reference to observations performed in the Venice Lagoon, the note describes: (i) new, 2-cm resolution, characterizations of channel network geometry obtained from “proximal sensing” photographic observations; (ii) the reliable quantitative maps of salt-marsh vegetation which may be retrieved from hyperspectral remote sensing data and field ancillary observations; (iii) a synthesis of recent and new analyses of the statistical properties of vegetation and landform spatial organization, that may be inferred from the maps so derived; (iv) recent and new conceptual and quantitative ecological and geomorphic models developed and validated by remote-sensing and field observations. A coherent observational and theoretical eco-morphodynamic framework is then proposed. 相似文献
13.
海桑属红树植物遗传多样性和引种关系研究 总被引:8,自引:2,他引:8
以海南东寨港红树林自然保护区内无瓣海桑(Sonneratia apetala)、海南海桑(S.hainanensis)、拟海桑(S.paracaseolaris)、杯萼海桑(S.abla)、大叶海桑(S.ovata)、海桑(S.caseolaris)等6种海桑属红树植物为材料,对15个有效引物进行RAPD分析,共扩增出512条带,其中多态性条带为297,占总扩增条带的58.01%.Nei指数法分析和UPGMA统计分析表明,6种海桑属红树植物分为A,B,C3个组,平均遗传距离为0.38.A组包括无瓣海桑、海南海桑、大叶海桑、怀萼海桑,其中无瓣海桑、海南海桑、大叶海桑处于同一个亚组.B组包括拟海桑.C组包括海桑.对海南和福建无瓣海桑种群进行RAPD分析.对Shannon表型多样性指数统计结果表明,福建种群为0.669,海南种群为0.671,各种群遗传变异较大,这与无瓣海桑种群广泛的适应性相一致.对种群间的Shannon表型多样性指数分析表明,种群内的遗传变异占整个遗传变异的93.3%,而种群间的遗传变异仅占6.7%.这表明无瓣海桑种群的大部分遗传变异存在于种群内,而种群间的遗传变异较小.由此可见,无瓣海桑基因组丰富的多样性,是使其由海南成功引种到福建的重要因素. 相似文献
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15.
阳江东平核电站邻近海区鱼卵和仔鱼调查研究 总被引:9,自引:0,他引:9
广东阳江东平核电站邻近海区生态调查于1998年4月(春季)和10月(秋季)进行。春季采获鱼卵101个、仔鱼45尾,隶属于4目9科11种和4个未定种;秋季采获鱼卵82个、仔鱼104尾,隶属于5目9科13种和3个未定种。对一些主要种类如康氏小公鱼Anchoviella commersoni、裘氏小沙丁鱼Sardinella jussieu、斑鲦Clupainddon punctatus、杜氏棱鳗Thrissa dussumieri、无齿鲦Andontostoma chacunda等的数量分布特征作了描述。就影响鱼卵、仔鱼种类数量分布的因素作了探讨,还对核电站建成后温排水对鱼卵、仔鱼的影响进行了预测。 相似文献
16.
植物硅酸体的研究及在我国第四纪地质学中的初步应用 总被引:8,自引:0,他引:8
本文简述了国外植物硅酸体(植物蛋白石)这门新兴学科的进展情况,介绍了植物硅酸体研究在我国第四纪地质学中如古气候与古环境、地层时代、考古等方面的初步应用。 相似文献
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18.
气候转型与早期人类迁徙 总被引:4,自引:0,他引:4
目前的旧石器考古证据表明,更新世早期可能发生了两次人类迁徙浪潮,时间分别在1.8-1.6MaBP和1.0MaBP左右,第一阶段,古人类演化为直立人并开始走出非洲、迁徙至其它中低纬度的热带-亚热带地区;第二阶段,直立人开始占据中高纬度的温带和干旱-半干旱地区。这两个阶段也是第四纪气候发生转型、环境产生重大调整的时期。二者在发生时间上的一致性揭示了它们之间的内在联系,推测气候转型时期环境转变是这两次人类迁徙浪潮的主要驱动力。 相似文献
19.
Abstract. The marine plant communities of the littoral zone in different biotopes of the Greek coasts were investigated in 1980-81. Seasonal distribution and variation of marine plant biomass were assessed. The communities of Cystoseira crinita and C. compressa were outstanding with maximum biomass during the summer months. Corallina officinalis and Pterocladia capillacea + Viva rigida communities predominated with maximum biomass in autumn and exhibited a decrease in winter, except in stressed biotopes. The species diversity and productivity of seaweeds along the Greek coasts are interpreted in relation to a number of environmental parameters. 相似文献
20.
虾肤诱食剂改善南美白对虾植物蛋白日粮的作用 总被引:6,自引:0,他引:6
用900尾平均体质量为0.106 g/尾±0.012 g/尾的南美白对虾(Peneausvannamei)进行虾肽改善植物蛋白日粮试验,结果表明:(1)大豆粕、杂粕组南美白对虾的成活率显著高于鱼粉组(P<0.05);(2)大豆粕、鱼粉组南美白对虾相对生长率、饲料系数、虾体组成相似,杂粕组最差,且与大豆粕、鱼粉组有显著性差异(P<0.05)。结果表明,在南美白对虾日粮中虾肽作为营养性诱食剂可显著改善植物蛋白的适口性,提高南美白对虾对大豆蛋白的的消化吸收功能,达到与鱼粉组相同的养殖效果,从而明显降低南美白对虾日粮成本。 相似文献