徐州市云龙湖沉积物中有机氯农药的污染研究

利用GC-ECD法对云龙湖10个站位表层沉积物中有机氯农药进行分析测定.所测样品中有机氯农药总浓度为2.50～11.35 ng/g,其中DDTs、HCHs每个采样点均有检出.与国内其它地区不同水体表层沉积物中DDTs、HCHs的含量相比,云龙湖沉积物中有机氯农药含量相对较低.多数站位点的有机氯农药来自早期残留或施用农药长期风化后的土壤,但是也不排除个别点位有新的污染源输入.     

北海近岸海域表层沉积物中DDTs、PCBs的分布、来源与生态风险分析

为评价广西北海市近岸海域表层沉积物中滴滴涕(DDTs)和多氯联苯(PCBs)的生态风险水平,于2017年8月使用挖斗式采泥器采集北海市近岸海域17个站点的表层沉积物样品,采用气相色谱法测定样品中DDTs(pp′-DDE、op′-DDT、pp′-DDD、pp′-DDT)和PCBs(三氯联苯PCB28,四氯联苯PCB52,五氯联苯PCB101、PCB112、PCB118,六氯联苯PCB138、PCB152、PCB153,七氯联苯PCB180和八氯联苯PCB198)的含量,分析其组分特征,并对沉积物中DDTs和PCBs进行生态风险评价。结果表明:北海近岸海域表层沉积物中持久性有机污染物(Persistent Organic Pollutants,POPs)平均含量(ng·g-1,干重)为PCBs(3.08)DDTs(0.89);污染物等值线图表明近岸海域表层沉积物中的DDTs、PCBs含量高于远岸海域,DDTs含量高值区主要在北海港泊位及营盘港海域,PCBs含量高值区主要在北海港泊位、营盘海域及铁山港湾口海域。DDTs 4种同系物平均百分含量排序为pp′-DDE(46.4%)pp′-DDT(21.8%)op′-DDT(20.5%)pp′-DDD(11.3%),pp′-DDE为沉积物DDTs中的主要成分;五氯联苯PCB101和七氯联苯PCB180为沉积物中PCBs的主要成分;所有站位中DDTs、PCBs的含量平均值均低于一类标准(GB18668-2002),污染程度总体较轻;有17.6%的站位DDTs含量介于生态风险效应区间低值(Effects Range Low,ERL)和生态风险效应区间中值(Effects Range Median,ERM)间。北海市近岸海域表层沉积物中DDTs、PCBs残留水平生态风险总体较低。     

海河与渤海湾沉积物中PCBs和OCPs的分布特征

环境中的持久性有机污染物会对人类和生态系统造成严重危害.为了了解其在典型区域内的分布状况,采用气相色谱法对海河与渤海湾沉积物样品中的多氯联苯(PCBs)和有机氯农药(OCPs)进行了分析测定.结果表明,研究区域内PCBs、六六六和滴滴涕的含量(千重)分别为0.34～81 ng·g-1·0.09～150ng·g-1,0.18～4100ng·g-1.与国内外类似区域的研究相比,海河沉积物中PCBs和OCPs污染情况比较严重.渤海湾则处于一般水平.污染物的可能来源有两个;一是来自上游河流的输入,二是来自河口附近的化工生产.     

福建兴化湾沉积物中多氯联苯的残留和风险评价

利用GC - MS对福建兴化湾15个表层沉积物样品中多氯联苯(PCBs)的含量进行了定量分析,并探讨了其在沉积物中的空间分布与来源.结果表明:PCBs的含量范围为:23.81～37.18 ng/g,平均值为27.85ng／g.主成分分析表明,PCBs同系物组成以3～5氯为主,占总PCBs含量的80％左右,这与中国PC...     

青岛近海表层沉积物中多氯联苯的分布

利用气相色谱-质谱联用技术对青岛近海17个站位表层沉积物中13种多氯联苯(PCBs)的分布特征、同族体的含量分布进行了初步分析,并且进行了PCBs的污染来源探讨及状况评价。13种PCBs的总量的范围为:(1.51～43.72)ng/gdw,总量平均值的分布特征为:西南近岸>胶州湾内>东北近岸,13种PCBs中,主要以低氯代的PCBs为主。青岛近海的PCBs污染属于轻度污染,整个调查区域属于低风险生态区。     

北京石景山区大气中多氯联苯的研究

为了解北京石景山区大气中多氯联苯的含量分布情况,利用气相色谱对北京石景山区大气中PCBs(Polychlorinated biphenyls,PCBs)含量进行了分析测定.分析结果表明:84种PCBs在所有样品中都有检出,气态样品中总的PCBs平均含量为785.59 pg/m3,颗粒物样品中总的PCBs平均含量为518.90 pg/m3.所有样品中都是四氯取代的PCB占最大比例, 整体都以3～5氯的低氯PCB为主. 颗粒物中6～9氯的高氯取代PCBs含量稍高于气态样品中.     

长江口表层沉积物中多氯联苯残留和风险评价

采用GC-ECD(gas chromatography-electron capture detector)对14种多氯联苯(polychlorinated biphenyls,PCBs)在长江口及东海近岸沉积物中的残留水平进行了测定,对其分布、组分特征、来源及生态风险水平进行了探讨.结果表明:多氯联苯在表层沉积物中的...     

南黄海表层沉积物中生源要素的分布规律及其环境意义

【目的】研究南黄海表层沉积物中生源要素的分布规律及其影响因素。【方法】通过测定南黄海82个站位表层沉积物样品中生源要素的含量及表层沉积物的平均粒径,分析研究区表层沉积物中生源要素和沉积物粒径的分布特征,并从表层沉积物中有机质来源、沉积物粒度、水动力作用和环境等因素探讨其对生源要素分布的影响。【结果】南黄海表层沉积物中生源要素总有机碳(TOC)、总氮(TN)及总磷(TP)的含量与平均粒径存在显著的相关关系,近岸沉积物粒度较大,对应生源要素的含量较低,在南黄海中部海区的沉积物粒度较细,各生源要素的含量较高。【结论】表层沉积物的粒度是影响生源要素含量分布的主要因素,即粒度越细,表层沉积物中生源要素含量越高。同时,有机质来源和水动力作用在一定程度上也影响和控制着表层沉积物粒度及生源要素的分布。生源要素TP分别与TOC、TN之间相对较弱的相关关系和近岸河口等地生源要素的高值表明,可能存在其他外部环境因素也会对其含量造成影响。     

珠海市马骝洲水道重金属分布与潜在生态风险评价

为了解珠江口主要水道——马骝洲水道重金属污染现状及其潜在生态风险,在6个站位对该水域的海水、沉积物和底栖贝类体中的6种重金属(Hg、Cd、Pb、Cu、Zn、As)的含量与空间分布特征进行了研究,并采用污染指数法和潜在生态风险指数法对海水和沉积物重金属的污染程度和潜在生态风险水平进行了评价.结果表明,大、小潮期海水中各重金属平均含量相近,且在大潮期空间分布不规则.仅有部分站位Hg超过海水水质二类标准,海水综合污染指数大潮期(0.35)>小潮期(0.25);表层沉积物中Cd、Cu、As和Hg的平均含量达到《海洋沉积物质量标准》二类标准,各重金属的空间分布呈波状分布.以污染指数评价,沉积物中主要重金属污染元素为Cd,其次为Hg和Cu,均达到强污染水平,其中Cd和Hg达到强至极强生态危害等级.以生态风险指数评价调查水域沉积物在总体上处于高潜在生态风险水平(RI＝318.9);调查水域底栖贝类体内重金属含量仅有Cd和Pb超标为海洋贝类质量标准二类.     

珠江口以外海域温、盐度的断面分布特征--2001年5月与2002年11月航次

通过2001年5月与2002年11月珠江口以外海域的CTD观测资料，分析调查海域两个航次的温、盐断面分布特征，并将表层温度特征与卫星遥感图象进行比较．结果表明：（1）2001年5月，珠江口以外海域可观察到较弱的上升流迹象；而2002年11月除了陆坡处的海水有涌升趋向外，未见其它上升流迹象．（2）受径流的影响，2001年5月珠江口外表层盐度水平及垂直梯度均较大．（3）两个航次在远岸站位均未形成明显的温跃层，但具有较弱的盐跃层，2001年5月和2002年11月的盐跃层分别位于10～90m和100～120m．（4）两个航次在远岸站位的100-250m层均可观察到部分黑潮次表层水．     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that