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1.
牛头岗遗址是江苏南京较大的古文化遗址,遗址文化层中植硅体组合揭示在新石器晚期(约3500Cal.aBP前),南京地区气候偏暖偏湿;商代(约3500—3000Cal.aBP),气候温暖湿润;西周早期(约3000Cal.aBP后),气候又偏暖偏湿。明显的气候波动与全新世中晚期全球气候变化可以对比。相邻何颖遗址的文化内涵和哺乳动物遗存,与牛头岗植硅体组合反映的植被与生态比较一致。新石器晚期至西周时期的气候与环境适宜古代先民的繁衍与生存,南京及滁河流域古文化内涵丰富。  相似文献   

2.
杨志荣 《生态学报》2001,21(4):538-543
以全封闭湖泊调角海子湖相沉积的高分辨率采样为基本分析材料,采用孢粉分析,沉积地球化学分析,14C测年等多种分析手段,对调角海子地区全新世气候与环境进行了综合研究,结果表明:全新世气候与环境演化可划分为5个阶段,其中后两个阶段又可分为3个亚段;全新世大暖期的时代为9400-3800aBP;全新世大暖期具有二分性;6900-6300aBP为全新世气候最适宜的鼎盛期,当时气温比现在高2-3度,降水量至少高于现代150-200mm,植被为针阔叶混交林。  相似文献   

3.
成都平原4 000aBP以来的孢粉记录与环境变化   总被引:1,自引:0,他引:1  
成都平原晚全新世以来沉积的泥质层发现丰富的孢粉。根据孢粉成分组合特征和生态类型可划分出5个孢粉组合带,结合剖面上6个14^C测年数据,提出在过去的4000a研究区植被类型及气候环境经历了5个阶段的变化:3800-3600aBP为亚热带常绿阔叶林,气候暖偏湿;3600-3400aBP为含常绿树种的落叶阔叶林,气候温暖湿润;3400-2600aBP为草/湿地,气温下降,环境更潮湿;2600-900aBP为落叶阔叶林,温度又开始逐渐回升,气候温和偏湿;900-300aBP再次变为草/湿地,偏干冷的气候环境。  相似文献   

4.
长白山拥有亚洲目前保存较为完好的温带山地森林生态系统,由于近年来无火事件发生而积累了大量可燃物,火灾隐患逐年增加,重建古火历史找出火事件发生规律有助于现代火灾的有效防控。本文以长白山区孤山屯泥炭剖面的68个样品为研究载体,选取炭屑作为主要指标反演了长白山全新世以来的火事件演化历史;并结合前人利用孢粉、植硅体等代用指标重建的古环境、古气候特征,分析了火事件的成因机制。在11 686-10 883 cal aBP、7 336-2 624 cal aBP、2 624-1 189 cal aBP,炭屑浓度较高,古火事件发生频繁,强度较大;在10 883-7 336 cal aBP、1 189 cal aBP至今,炭屑浓度较低,古火事件发生频率较小,强度相对较弱。气候和植被对于火事件的影响贯穿了整个全新世时期,火事件多发生在寒冷干燥气候时期且以区域性火事件为主;近千年以来,人类活动与火山喷发对火事件的影响显著,局域性火事件比例逐渐增多。  相似文献   

5.
本研究对浙江萧山SE2钻孔近50m沉积物岩心进行了详细的有孔虫定量统计分析,并结合测年资料重建了冰后期以来钱塘江沉积河谷的环境演化过程。有孔虫群落特征反映的古环境变化与沉积相分析结果一致。有孔虫资料显示:大约1万年以来该地区受到海水的影响、以胶结质壳Textularia-Reophax组合为特征,并在中全新世海水深度到达最大、以近岸浅水组合Ammonia beccarii-Elphidium magellanicum为代表,而晚全新世以来在全球海平面下降的影响下、该地区海水变浅的同时,却由于狭窄的特殊河口地形,水动力相对较强,显示强潮型河口地区特有的近岸分子Ammonia beccarii,Elphidium advenum和相对较深水分子Ammonia compressiuscula共存的底栖有孔虫群落特征。  相似文献   

6.
通过对浙江萧山白马湖地区BMH全新世钻孔沉积物中硅藻及其主成分进行分析,揭示研究区9 600—7 230cal a BP期间与海平面相关的沉积环境变化。结果显示9 600—8 950cal a BP期间,硅藻组合以淡水种为优势种,未出现海水种,反映研究区为淡水沼泽环境,没有受到海水的影响;8 950—8 600cal a BP期间,硅藻组合中半咸水种出现且含量逐渐增加,但仍以淡水种为主要优势种,表明研究区受到间歇性潮汐或风暴潮的影响,对应于高潮滩-潮上带的沉积环境;半咸水种和海水种含量在8 600—8 300cal a BP期间显著增加,而淡水种的含量明显降低,说明当时海平面显著上升,白马湖地区处于潮下带;在8 300—7 230cal a BP段的沉积物中未发现硅藻壳体,可能与当时研究区干涸成陆或埋藏条件有关,对应于跨湖桥文化时期(8 000—7 000cal a BP)。白马湖地区硅藻记录的8 600—8 300cal a BP海平面上升事件,在同时期的长江三角洲、东南亚乃至全球其他很多地方均有记录,可能与该时期劳伦太德冰盖融水事件(Laurentide Ice Sheet)以及Agassiz-Ojibway湖溢水事件所导致的全球海平面快速上升有关。  相似文献   

7.
内蒙古高原东南部森林草原过渡带位于中国东部季风气候尾闾区 ,是全球变化研究的关键区域。这一地区降水量存在着明显的东南至西北 (SE_NW)梯度。在现代植被和表土花粉分析的基础上 ,建立了内蒙古高原东南缘森林草原过渡带孢粉_降水量转换函数。将研究区森林草原过渡带内 3个湖泊沉积剖面的孢粉分析结果代入转换函数 ,定量恢复了这一地区全新世降水量的变化过程。结果表明 :3个剖面全新世以来降水量变化的过程存在明显的差异 ,北部的好鲁库剖面在 110 0aBP以前一直呈减弱的趋势 ,而南部的碌轴湾剖面和小牛场剖面降水量在分别在 780 0 - 6 2 0 0aBP和 72 0 0 - 5 0 0 0aBP出现降水量的峰值 ,作者推断这种时空差异性与西南季风的影响、地形条件的差异有关。  相似文献   

8.
浙江岸外东海内陆架MD06-3040柱状样完整保存有10.6 cal.kaPB以来的全新世沉积记录,采取257个沉积物样品进行了有孔虫和介形虫定量分析.依据丰度上的优势成分和特征种的分布,识别出6个底栖有孔虫组合和4个介形虫组合.应用属种组合和不同生态(表生/内生、内陆架/中-内陆架、暖水)种的丰度,探讨了研究区全新世以来的古环境变迁.分析结果揭示了研究区全新世早期海面快速上升,沉积环境由滨岸内陆架(10.6-9.8Cal.kaBP)、内陆架外缘(9.8-7.8 cal.kaBP)转变至中陆架内侧并达全新世最高海面(7.8-3.4 Cal.kaBP).台湾暖流在8.O Cal. kaBP起开始发育,并在5.7-2.8和0.7-O cal.kaBP二个时期派生出明显的上升流.台湾暖流及其所派生的上升流是造成东海陆架泥质快速沉积的最主要原因.依据浮游有孔虫Globigerina bulloides的丰度变化,推测浙闽沿岸流在4.9-3.2 Cal.kaBP时期最为强盛.  相似文献   

9.
化石硅藻新指标在西藏昂仁湖环境演变中的应用   总被引:7,自引:0,他引:7  
应用化石硅藻属组合和属系数两个新指标对西藏南部昂仁湖 (2 9°18′N ,87°11′E)剖面硅藻记录进行解析 ,得出该地区在 110 0 0— 6 0 0 0aBP间经历了寒冷期 (110 95— 9970aBP)→温和期 (9970— 9870aBP)→升温期(9870— 9770aBP)→凉干期 (9770— 8740aBP)→超高温期 (8740— 85 90aBP)→高温期 (85 90 - 5 970aBP)的演变序列。同时发现在寒冷期存在增温 (10 710aBP)和降温 (10 430aBP)波动 ;凉干期 880 0— 876 0aBP附近存在强低温事件 ;超高温期中的最高温出现在 86 80aBP附近 ;在高温期 80 0 0— 792 0aBP和 7170— 70 90aBP两个小时段分别存在增降温波动。在 6 430aBP附近存在明显的旱化现象。同时发现在研究时期除了存在 10 0 0年的气候变化周期外还存在 15 0— 2 0 0年左右的气候转型期。昂仁湖发育则至少经历了缓慢扩张 (110 0 0— 8740aBP)→快速扩张 (8740— 85 90aBP)→缓慢退缩 (85 90— 5 970aBP) 3个大阶段。也因此验证化石硅藻属组合和属系数两个新指标至少在富含硅藻的封闭湖盆环境演变研究中的有效性和便捷性  相似文献   

10.
通过对长江三角洲锦溪地区白莲湖附近人工剖面的孢粉研究,重建该地区7 230cal a BP前后的植被和气候。孢粉植物群反映当时气候略有波动,但整体上与全新世气候适宜期的温暖环境相一致。孢粉自下而上可以细分为4个组合带:Zone 1青冈栎含量丰富,反映温暖气候;Zone 2落叶栎有所增多,气候稍有转凉;Zone 3青冈栎含量再度增高,气候变暖;Zone 4松属和落叶栎明显增多,气候再度转凉。从沟鞭藻和相关孢粉类型的分布分析,除底部12号样品因孢粉含量低而未予考虑外,其它样品都指示沉积时期当地受到海水的影响。其中Zone 1和Zone 2孢粉植物群指示两次海水的进退过程。当前孢粉研究结果很好地反映出长江三角洲地区全新世大暖期的气候变化特征,以及与当时海平面变化的关联。  相似文献   

11.
A new polynitro cage compound 2, 4, 6, 8, 10, 12, 13, 14, 15-nonanitro-2, 4, 6, 8, 10, 12, 13, 14, 15-nonaazaheptcyclo [5.5.1.1(3,11).1(5,9)] pentadecane (NNNAHP) was designed in the present work. Its molecular structure was optimized at the B3LYP/6-31 G(d,p) level of density functional theory (DFT) and crystal structure was predicted using the Compass and Dreiding force fields and refined by DFT GGA-RPBE method. The obtained crystal structure of NNNAHP belongs to the P-1 space group and the lattice parameters are a = 9.99 ?, b = 10.78 ?, c = 9.99 ?, α = 90.01°, β = 120.01°, γ = 90.00°, and Z = 2, respectively. Based on the optimized crystal structure, the band gap, density of state, thermodynamic properties, infrared spectrum, strain energy, detonation characteristics, and thermal stability were predicted. Calculation results show that NNNAHP has detonation properties close to those of CL-20 and is a high energy density compound with moderate stability.  相似文献   

12.
Summary Concentration of N, P, K, Ca, Mg and S in summer groundnut crop was higher than in kharif while Zn, Fe, Mn and Cu contents were higher in summer crop. Kernel's N, P and Zn; Leaflet's Ca and Mn; Stem's K and Fe; Root's S and Cu and Petiole's Mg contents were highest. Shell's N, P, K, Mg, S, Zn and Cu; Kernel's Ca, Fe and Mn contents were the least. N, P, K, S, Zn and Cu concentrations decreased linearly as the crop grew. Ca, Mg, Fe and Mn concentrations did not display any distinct pattern. Ca concentration was positively correlated with pod yield in both the seasons.  相似文献   

13.
14.
The goal of this article was to establish reference ranges of the concentration of trace elements in human serum and to compare these results with those reported by other authors. We describe the sample preparation and measurement conditions that allow the rapid, precise, and accurate determination of Al, As, B, Be, Cd, Co, Cu, Fe, Li, Mn, Mo, Ni, Rb, Se, Sr, and Zn in human serum samples (n=110) by inductively coupled plasma-mass spectrometry (ICP-MS). Accuracy and precision were determined by analyzing three reconstituted reference serum samples by comparison with other methods and by the standard addition procedure. The advantages of the ICP-MS method include short time of analysis of the elements mentioned, low detection limit, high precision, and high accuracy. Disadventages include a high risk of contamination due to the presence of some of the elements of interest in the environment, the relatively delicate sample handling, and the high cost of the equipment.  相似文献   

15.
This report attempts to formulate reference ranges of elemental concentrations for 15 trace elements in selected human tissues and body fluids. A set of samples consisting of whole blood, blood serum, urine, milk, liver, and hair were chosen and considered for 15 elements of biological significance: As, Cd, Co, Cr, Cu, F, Fe, I, Hg, Mn, Mo, Ni, Pb, Se, and Zn. The results represent wholly or partially data received from 40 countries of the global regions of Africa, Asia, Europe, North, South, and Central America, Australia, and New Zealand. This survey, even if qualitative, has been useful in demonstrating certain trends of trace-element scenarios around the world. It is of course recognized that both diet and environment exert a strong influence on the distribution pattern of several elements, such as As, Cd, Mn, Pb, Se, and Zn. A limited comparison of the available information on soil status of different countries reflected some interesting associations for elements, such as Mn and Zn. Importantly, this study revealed that only a few countries were in a position to identify a reasonable amount of data on samples requested for this project. Regretably, for a number of countries, any dependable data for even such essential elements as Cu, Fe, and Zn were not available. In view of the nutritional importance of many elements, the time is ripe for concerted efforts by intergovernmental agencies to initiate investigations or commission task forces/projects to generate reliable reference data for selected global regions, which sadly lack data of any kind at present.  相似文献   

16.
The variation with age of the 18 trace element mass fractions and some histological characteristics of intact prostate glands of 50 subjects aged 0–30 years was investigated by instrumental neutron activation analysis, inductively coupled plasma atomic emission spectrometry, and a quantitative morphometric analysis. Mean values ± standard error of the mean (M ± SΕΜ) for the mass fractions (in milligrams per kilogram wet tissue) of these trace elements in pre-puberty were: Al 28.5 ± 9.0, B 0.40 ± 0.11, Ba 1.48 ± 0.44, Br 10.5 ± 1.5, Ca 241 ± 30, Cl 3,203 ± 278, Cu 3.51 ± 0.89, Fe 33.7 ± 4.1, K 2,364 ± 145, Li 0.020 ± 0.004, Mg 153 ± 23, Mn 0.46 ± 0.06, Na 2,286 ± 130, P 1,391 ± 100, S 1,698 ± 132, Si 62 ± 11, Sr 0.38 ± 0.08, and Zn 27.6 ± 2.3. During puberty and postpuberty, when there is a significant increase in circulating androgens, the mean values were: Al 7.2 ± 1.4, B 0.21 ± 0.05, Ba 0.25 ± 0.06, Br 5.8 ± 1.0, Ca 433 ± 81, Cl 2,314 ± 201, Cu 1.77 ± 0.13, Fe 20.9 ± 1.6, K 2,585 ± 118, Li 0.0088 ± 0.0014, Mg 232 ± 27, Mn 0.34 ± 0.04, Na 1,875 ± 107, P 1,403 ± 98, S 1,673 ± 73, Si 22.2 ± 3.1, Sr 0.22 ± 0.03, and Zn 93.3 ± 8.9. Mean values (M ± SΕΜ) of percent volumes (%) of the stroma, epithelium and lumen in the prostate before puberty were 73.4 ± 2.6, 20.4 ± 1.7, and 4.45 ± 0.94, respectively, versus 46.5 ± 2.5, 38.5 ± 1.9, and 14.9 ± 1.2 during puberty and postpuberty. This work’s results confirm that the Zn mass fraction in prostate tissue is an androgen-dependent parameter. For the first time it has been demonstrated that the glandular lumen is a main pool of Ca, Mg, and Zn accumulation and that the stroma is a main pool of Al, B, Ba, Br, Cl, Cu, Fe, Mn, Na, and Si accumulation in the normal human prostate, for the age range 0–30 years. It was concluded that the Ca, Mg, and Zn binds tightly within the prostatic fluid, because the volume of glandular lumen reflects the volume of prostatic fluid.  相似文献   

17.
The effect of age and gender on major, minor, and trace element contents in the intact rib bone of 80 relatively healthy 15–55-year-old women and men was investigated. Contents or upper limit of contents of 16 chemical elements in the rib bone were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). Mean values (M?±?SΕΜ) for the mass fraction of Ba, Ca, Cu, Fe, K, Li, Mg, Na, P, S, Sr, and Zn (milligram per kilogram of dry bone) were as follows: 2.54?±?0.16, 171,400?±?4,050, 1.35?±?0.22, 140?±?11, 1,874?±?71, 0.049?±?0.011, 2,139?±?38, 5,378?±?88, 75,140?±?1,660, 1,881?±?51, 291?±?20, and 92.8?±?1.5, respectively. The upper limits of contents of Al, B, Mn, and V were <7.20, <0.65, <0.36, and <0.03, respectively. Statistically significant tendency for the Ca, Mg, and P content to decrease with age was found in the human rib bone, regardless of gender. The mass fraction of Fe in the male rib bone increases with age. It was shown that higher Ca, Mg, Na, P, and Sr mass fractions as well as lower Fe content were typical of female ribs as compared to those in male ribs.  相似文献   

18.
19.
《Ibis》1894,36(3):447-460
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20.
Oral cancer is one of the main causes of cancer-related deaths in South-Asian countries. There are very limited treatment options available for oral cancer. Research endeavors focused on discovery and development of novel therapies for oral cancer, is necessary to control the ever rising oral cancer related mortalities. We mined the large pool of compounds from the publicly available compound databases, to identify potential therapeutic compounds for oral cancer. Over 84 million compounds were screened for the possible anti-cancer activity by custom build SVM classifier. The molecular targets of the predicted anti-cancer compounds were mined from reliable sources like experimental bioassays studies associated with the compound, and from protein-compound interaction databases. Therapeutic compounds from DrugBank, and a list of natural anti-cancer compounds derived from literature mining of published studies, were used for building partial least squares regression model. The regression model thus built, was used for the estimation of oral cancer specific weights based on the molecular targets. These weights were used to compute scores for screening the predicted anti-cancer compounds for their potential to treat oral cancer. The list of potential compounds was annotated with corresponding physicochemical properties, cancer specific bioactivity evidences, and literature evidences. In all, 288 compounds with the potential to treat oral cancer were identified in the current study. The majority of the compounds in this list are natural products, which are well-tolerated and have minimal side-effects compared to the synthetic counterparts. Some of the potential therapeutic compounds identified in the current study are resveratrol, nimbolide, lovastatin, bortezomib, vorinostat, berberine, pterostilbene, deguelin, andrographolide, and colchicine.  相似文献   

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