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在塔西北阿克苏露头区发育多套类型不同的下寒武统肖尔布拉克组风暴岩，它们宏观上与微生物丘混生或共生，微观上可见不同类型的微生物结构，但与此相关的研究甚少。以露头观察和室内鉴定为基础，在苏盖特布拉克地区和昆盖阔坦地区划分出4类8种各具特色的微生物丘-风暴岩沉积序列，并归纳总结了塔西北地区下寒武统肖尔布拉克组风暴沉积模式，认为其发育位置和沉积特征主要受控于"三面"，包括平均海平面（MSL）、正常浪基面（FWB）和风暴浪基面（SWB）；"四期"，包括平静期、高峰期、衰减期与停息期；"五流态"，包括风暴涡流、风暴下部回流（包括风暴碎屑流和风暴浊流）沉积与风暴上部回流（包括风暴漫流和风暴潮流）。另外古风暴中心的发育位置也可影响风暴沉积特征。最后在前人研究的基础上，对"贫乏骨骼的风暴海"的形成条件进行探讨。 相似文献
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An in vivo three-dimensional fluorescence method for the determination of algae community structure was developed by parallel factor analysis(PARAFAC) and CHEMTAX. The PARAFAC model was applied to fluorescence excitation-emission matrix(EEM) of 60 algae species belonging to five divisions and 11 fluorescent components were identified according to the residual sum of squares and specificity of the composition profiles of fluorescent. By the 11 fluorescent components, the algae species at different growth stages were classified correctly at the division level using Bayesian discriminant analysis(BDA). Then the reference fluorescent component ratio matrix was constructed for CHEMTAX, and the EEM–PARAFAC–CHEMTAX method was developed to differentiate algae taxonomic groups. The correct discrimination ratios(CDRs) when the fluorometric method was used for single-species samples were 100% at the division level, except for Bacillariophyta with a CDR of 95.6%. The CDRs for the mixtures were above 94.0% for the dominant algae species and above 87.0% for the subdominant algae species. However, the CDRs of the subdominant algae species were too low to be unreliable when the relative abundance estimated was less than 15.0%. The fluorometric method was tested using the samples from the Jiaozhou Bay and the mesocosm experiments in the Xiaomai Island Bay in August 2007. The discrimination results of the dominant algae groups agreed with microscopy cell counts, as well as the subdominant algae groups of which the estimated relative abundance was above 15.0%. This technique would be of great aid when low-cost and rapid analysis is needed for samples in a large batch. The fluorometric technique has the ability to correctly identify dominant species with proper abundance both in vivo and in situ. 相似文献
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核形石是微生物岩的一种,长期受到地质学家的广泛关注。目前在核形石的展布模式、沉积环境以及微生物特征和形成机制方面的研究仍显不足。北京西郊丁家滩剖面地层出露良好且保存完整,其寒武系昌平组的早期高位体系域主要沉积在潮下-潟湖环境中。受控于三级以下海平面以及水动力条件,早期高位体系域自下而上发育了三套形态各异的核形石层。第一套毫米级核形石零星分布于早期高位体系域下部,不具明显核心,包壳内见大量泥晶物质及砂屑、生屑。第二套厘米级-亚厘米级椭球状核形石集中分布于早期高位体系域中部,具有明显核心,包壳主要由亮纹层、菌纹层、生屑层和包壳层组成。第三套厘米级椭球/叶状核形石集中分布于早期高位体系域上部,具有明显核心,包壳主要由亮纹层组成,菌纹层含量较少。镜下鉴定结果表明由亮/暗纹层交互而成的核形石包壳具有不同的显微/超微结构,代表了微生物席与沉积环境的不同互动方式。分析其形成环境可知,北京西郊丁家滩剖面寒武系昌平组以核形石为主的微生物岩,生物灭绝事件是其直接成因,但也许不是决定性因素。 相似文献
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芙蓉洞洞穴水离子浓度和元素比值变化特征及其环境意义 总被引：5，自引：3，他引：2
通过对芙蓉洞2006年3月—2009年2月期间泉水和洞穴滴水、池水的地球化学指标监测,结合当地的器测数据,初步认为洞穴滴水的Sr2＋、Ca2＋、Mg2＋浓度及其比值既取决于环境降水和温度的变化,也受到上覆岩土作用的影响。芙蓉洞外山上的6#泉水Ca2＋平均浓度为45.81 mg/L,洞内1#、3#滴水Ca2＋的平均浓度64.59 mg/L,2#和4#池水中由于Ca2＋沉积,浓度下降到24.74 mg/L,下降了大约61.7%。Mg2＋和Sr2＋的浓度在泉水、滴水和池水中的变化规律与Ca2＋基本一致。各种水体中Cl-的浓度变化幅度较小,平均浓度为1.720.2 mg/L。岩溶水与基岩作用时间长短以及运移过程中Ca2＋的前期沉积作用对各元素与离子含量变化具有重要作用。旱季Ca2＋的前期沉积作用和雨季基岩的溶蚀及雨水的稀释作用主导着岩溶水中Mg/Ca与Sr/Ca的变化,这些指标能对干旱和洪涝等极端气候事件做出响应。 相似文献
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北京西郊下苇甸地区下寒武统昌平组底部含燧石角砾白云岩之上发育的一套豹斑灰岩,实为发育在高能环境下的凝块石灰岩,宏观形态上可包括斑状凝块石、带状凝块石和网状凝块石3种,其成因多与厚微生物席相关,且分别具有不同的微观结构。露头实测和镜下观察结果表明凝块石的初始沉积组分受控于沉积大/微环境,且三者的互动决定了凝块石的最终沉积特征。该套沉积成因的凝块石,其白云质凝块不局限于潜穴,且潜穴内部见大量保存完好微生物结构和疑似球状原生白云石,因此这种白云质凝块很可能与微生物白云石化密切相关,并以此区别于局限于生物遗迹位置,且内部充填物为粉细晶白云石的成岩成因的豹斑灰岩。 相似文献
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利用三维荧光光谱(EEMs)-平行因子分析法(PARAFAC)研究了春季(2020年5月)和秋季(2020年10月)莱州湾海域荧光溶解有机物(FDOM)的来源及时空分布特征。莱州湾海域FDOM由2类共4个荧光组分组成：C1、C4为类蛋白质组分,分别为色氨酸和酪氨酸;C2、C3为类腐殖质组分。并对各组分的来源及分布特征分析：春季FDOM分布主要受到陆源输入的影响,其中表层C1、C2、C3也受微生物活动影响。秋季表层C1、C2、C3分布受到陆源输入和浮游植物生产共同影响,秋季表层C4主要受生物现场生产影响,秋季底层C1、C2、C3主要受陆源输入影响,C4受陆源输入和浮游植物生产共同影响。各荧光组分在表层的季节性差异主要是由于春季部分FDOM经陆源输入后受偏南风作用,在莱州湾西部及南部海域扩散。FDOM在底层的季节性差异主要由于受到沉积物再悬浮的影响。HIX高值分布表明莱州湾西部和南部FDOM受陆源输入影响显著,BIX高值分布表明莱州湾远海FDOM受生物活动影响程度较高。总体上,陆源输入影响莱州湾FDOM分布的主要因素。本文利用三维荧光光谱-平行因子分析法(EEMs-PARAFAC)技术结合多元统计方法,分析了莱州湾春秋季FDOM的来源以及分布差异,为其他海区FDOM研究提供补充。 相似文献
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开展广西洪涝灾害风险评估可为降低暴雨灾害损失提供理论支撑,利用中国长短历时暴雨雨量特征数据集(1961—2015年)中广西全部站点的气象数据,结合基础地理数据、社会经济数据,通过AHP-熵权法为各项洪涝因子赋权,并借助GIS技术分析并开展广西暴雨洪涝灾害风险评估。研究结果表明:广西高风险灾害地区约占全域的9%,低风险灾害地区约占15%。广西从东南沿海到西北内陆暴雨洪涝风险逐渐减低。其原因是南部雨量大,暴雨历时长,部分市区地势平坦且海拔低。一些地区经济发达、人口密集,造成受灾损失重,同时也加大了暴雨洪涝灾害的风险。研究可为广西暴雨洪涝灾害预防与治理提供决策参考。 相似文献
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栖霞市生木树泥石流隐患点为烟台市471处地质灾害隐患点其中1处,曾于1979年7月因暴雨引发泥石流灾害,给当地村民造成严重经济损失。以该泥石流沟流域作为研究区,并以区内泥石流发育的自然环境、基本特征及形成泥石流的地质条件、物源条件和水源条件等勘察成果为基础,综合分析区内泥石流发育特征、类型、形成机理、引发因素,并选取相关参数对泥石流基本特征值进行计算,为同类型泥石流的防治提供科学依据。综合研究确定区内泥石流易发程度为轻度易发,现阶段泥石流沟发展阶段为发展期,泥石流灾害趋于相对稳定,但一旦遭遇暴雨至特大暴雨,可能会再次引发泥石流地质灾害。 相似文献
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The southern Changjiang River Estuary has attracted considerable attention from marine scientists because it is a highly biologically active area and is biogeochemically significant.Moreover,land-ocean interactions strongly impact the estuary,and harmful algal blooms(HABs) frequently occur in the area.In October 2010 and May 2011,water samples of chromophoric dissolved organic matter(CDOM) were collected from the southern Changjiang River Estuary.Parallel factor analysis(PARAFAC) was used to assess the samples' CDOM composition using excitation-emission matrix(EEM) spectroscopy.Four components were identified:three were humic-like(C1,C2 and C3) and one was protein-like(C4).Analysis based on spatial and seasonal distributions,as well as relationships with salinity,Chl a and apparent oxygen utilization(AOU),revealed that terrestrial inputs had the most significant effect on the three humic-like Components C1,C2 and C3 in autumn.In spring,microbial processes and phytoplankton blooms were also important factors that impacted the three components.The protein-like Component C4 had autochthonous and allochthonous origins and likely represented a biologically labile component.CDOM in the southern Changjiang River Estuary was mostly affected by terrestrial inputs.Microbial processes and phytoplankton blooms were also important sources of CDOM,especially in spring.The fluorescence intensities of the four components were significantly higher in spring than in autumn.On average,C1,C2,C3,C4 and the total fluorescence intensity(TFI) in the surface,middle and bottom layers increased by123%–242%,105%–195%,167%–665%,483%–567% and 184%–245% in spring than in autumn,respectively.This finding corresponded with a Chl a concentration that was 16–20 times higher in spring than in autumn and an AOU that was two to four times lower in spring than in autumn.The humification index(HIX) was lower in spring that in autumn,and the fluorescence index(FI) was higher in spring than in autumn.This result indicated that the CDOM was labile and the biological activity was intense in spring. 相似文献