台山核电邻近海域春秋季浮游植物群落结构特征     

粟丽  黄梓荣  徐珊楠  陈作志 《海洋科学》2016,40(9):61-68

根据2013年4月(春季)和9月(秋季)2个航次调查数据,对台山核电邻近海域浮游植物种类组成、时空分布及多样性指数等群落特征进行了分析。共鉴定浮游植物3门61种,其中硅藻类48种,占78.69%;甲藻类11种,占18.03%;金藻类2种,占3.28%。种类组成以暖水种和广温种为主。浮游植物丰度均值春季(11.78×107个/m3)与秋季(29.37×107个/m3)无明显差异;然而丰度水平变化较大,整体表现为春秋两季核电站温排水口附近站位均低于远离站位。春秋两季浮游植物优势种共出现了7种,春季仅出现了中肋骨条藻Skeletonema costatum1种,优势度高达0.996;秋季出现了7种,包括中肋骨条藻(0.291)、柔弱拟菱形藻Pseudo-nitzschia delicatissima(0.222)、拟弯角毛藻Chaetoceros pseudocurvisetus(0.214)和并基角毛藻Chaetoceros decipiens(0.056)等。海域春季Shannon-Wiener多样性指数H′、Pielou均匀度指数J′和Margalef物种丰富度指数D均值分别为0.55、0.18和0.50;秋季分别为2.80、0.62和0.80。多样性指数显示台山核电附近海域水质状态受到了一定程度的污染。  相似文献   

Effect of the Dry Ashing Method on Cadmium Isotope Measurements in Soil and Plant Samples     

Wei‐Xin Lv  Hao‐Ming Yin  Meng‐Shu Liu  Fang Huang  Hui‐Min Yu 《Geostandards and Geoanalytical Research》2021,45(1):245-256

A dry ashing method is commonly used to remove organic material from samples prior to geochemical analysis. In the course of this study, the Cd isotope ratios of a series of soil and plant reference materials and samples were studied to evaluate the effect of the dry ashing method on measurement results of Cd isotope ratios. The samples were pre‐treated using the dry ashing method and high‐pressure bomb for comparison. The results show that the digestion using high‐pressure bombs did not lead to Cd loss, but using the dry ashing method would cause different proportions of Cd loss. The whole range of Cd isotope difference between two methods was from ?0.07‰ to 3.01‰. There was also an obvious difference in measured Cd isotope ratios from the same leaf sample pre‐treated independently by the dry ashing method, indicating that the amount of Cd loss and the effect on Cd isotope measurement during dry ashing is related to the properties of the samples. Therefore, dry ashing may not be appropriate for the removal of organic material in Cd isotope ratio measurement, especially for samples with high organic contents. The δ^114/110Cd values of reference materials NIST SRM 1573a and GSD‐30 are reported for the first time in this study.  相似文献   

Poor fen succession over ombrotrophic peat related to late Holocene increased surface wetness in subarctic Quebec,Canada     

MICHELLE GARNEAU  ALEXANDRE LAMARRE  ÉLISABETH C. ROBERT  GABRIEL MAGNAN  HANS ASNONG  STEVE PRATTE 《第四纪科学杂志》2013,28(8):748-760

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The cordierite‐bearing anatectic rocks of the higher Himalayan crystallines (eastern Nepal): low‐pressure anatexis,melt productivity,melt loss and the preservation of cordierite     

C. GROPPO  F. ROLFO  P. MOSCA 《Journal of Metamorphic Geology》2013,31(2):187-204

Cordierite‐bearing anatectic rocks inform our understanding of low‐pressure anatectic processes in the continental crust. This article focuses on cordierite‐bearing lithologies occurring at the upper structural levels of the Higher Himalayan Crystallines (eastern Nepal Himalaya). Three cordierite‐bearing gneisses from different geological transects (from Mt Everest to Kangchenjunga) have been studied, in which cordierite is spectacularly well preserved. The three samples differ in terms of bulk composition likely reflecting different sedimentary protoliths, although they all consist of quartz, alkali feldspar, plagioclase, biotite, cordierite and sillimanite in different modal percentages. Analysis of the microstructures related to melt production and/or melt consumption allows the distinction to be made between peritectic and cotectic cordierite. The melt productivity of different prograde assemblages (from two‐mica metapelite/metagreywacke to biotite‐metapelite) has been investigated at low‐pressure conditions, evaluating the effects of muscovite v. biotite dehydration melting on both mineral assemblages and microstructures. The results of the thermodynamic modelling suggest that the mode and type of the micaceous minerals in the prograde assemblage is a very important parameter controlling the melt productivity at low‐pressure conditions, the two‐mica protoliths being significantly more fertile at any given temperature than biotite gneisses over the same temperature interval. Furthermore, the cordierite preservation is promoted by melt crystallization at a dry solidus and by exhumation along P‐T paths with a peculiar dP/dT slope of about 15–18 bar °C^?1. Overall, our results provide a key for the interpretation of cordierite petrogenesis in migmatites from any low‐P regional anatectic terrane. The cordierite‐bearing migmatites may well represent the source rocks for the Miocene andalusite‐bearing leucogranites occurring at the upper structural levels of the Himalayan belt, and low‐P isobaric heating rather than decompression melting may be the triggering process of this peculiar peraluminous magmatism.  相似文献   

The influence of medium-range transport on O3 levels at a rural site in Israel     

Batia Lifshitz  Mordechai Peleg  Menachem Luria 《Journal of Atmospheric Chemistry》1988,7(1):19-33

Simultaneous ozone measurements were made at a rural site, 25 km SSW of the city of Jerusalem, and in the center of the city during a period of 28 months. The ozone data were supplemented by SO₂, NO/NO _x ,and meteorological measurements at both sites. Elevated ozone concentrations were recorded at the rural site, mostly during the spring months (May and June) during which the monthly averages and the monthly averages of the daily 30 min maximum levels equalled those measured in the city. During the summer months, both average and peak levels were lower at the rural site by 20 and 35 ppb. The increased ozone levels at the rural site were accompanied by a parallel increase of SO₂ and NO _x ,suggesting hat the excess ozone at the rural site is a result of a transformation during transport of air pollutants from coastal sources.  相似文献   

淮北煤田早二叠世化石植物古生态     

杜美利 《中国煤田地质》1994,6(4):21-25

淮北煤田早二叠世化石植物丰富，其形成于炎热多雨的热带滨海三角洲沉积体系中。下三角洲平原是该区化石植物最宜生长的地方。早二叠世该区化石植物常形成四类植物群落：森林沼泽植物群落、沿岸水生植物群落、高地植物群落、三角洲平原真蕨及种子蕨混生植物群落（早期）、树蕨－大羽羊齿类雨林植物群落（晚期）。随着时间的推移，这四类植物群落的结构及面貌发生着不断的变化；其演替显示，早二叠世晚期该区气侯更加湿热，雨林气侯更为普遍。  相似文献   

新型节水灌溉控制原理的应用研究   总被引：20，自引：0，他引：20       下载免费PDF全文

苏臣  孙一源 《水科学进展》1994,5(2):142-148

在土壤-植物-大气连续体系(SPAC)中,以植物茎、果微增长及其含水量变化作为植物需水信息建立的灌溉自动控制系统,可实现植物水分适度亏缺,有效调控其生长发育。实验结果表明,同充分供水的植株或树体相比,节水15.6%时,玉米长势良好,节水21.4%时,柑桔果实生长未受影响。  相似文献   

气候变化对中国木本植物物候的可能影响   总被引：76，自引：1，他引：76  

张福春 《地理学报》1995,50(5):402-410

本文根据我国的３０年的物候资料和气候资料的统计分析，论证了气温是影响中国木本植物物候的主要因子，在此基础上建立了物候与年平均气温的线性统计模式，又利用此模式分析计算了未来全球年平均气温升高０．５－２．０℃和未来大气中ＣＯ２浓度倍增而增暖情况下，我国主要木本植物物候期的大致变幅。  相似文献   

Application of the telluric and magnetotelluric methods in selection of sites for nuclear plants     

A. Ádám  J. Verö 《Journal of Earth System Science》1990,99(4):657-667

The paper deals with the application of the telluric method and of magnetotelluric soundings including experimental and model data on the localization of tectonic disturbances in connection with the selection of appropriate sites for nuclear plants.  相似文献   

辽南核电站厂址区断层的评价问题          下载免费PDF全文

李愿军 《地震工程学报》1994,16(3):47-53

作者通过对核安全法规的学习和前人对辽南核电站厂址区断层的调查，并结合对断层实际踏勘，认为厂址区附近的东岗断层属于现行法规（ＨＡＦ０１０１）中规定的能动断层。但是，仅此一点并不能构成对推荐厂址的威胁，因为断层距厂址直线距离约４ｋｍ，断层的地表或近地表错动不会直接影响到核反应堆的安全。  相似文献