基于蒙特卡洛模拟技术的杭嘉湖平原稻田土壤Cd安全阈值研究

安全的稻米产地环境是保障稻米镉含量不超标的基础,而正确确定稻米产地土壤镉安全阈值是进行产地安全管理的关键。为此,以杭嘉湖稻米主产区为例,通过土壤-稻米对应采样分别获得了研究区118个土壤-稻米样品,并基于监测数据采用线性回归与蒙特卡洛耦合模型法,回归方程法及吸收系数法构建了研究区稻米产地镉安全阈值。研究结果表明,土壤镉含量、土壤pH、土壤质地是影响稻米镉含量的主要因素。线性回归与蒙特卡洛耦合模型分析结果表明,在稻米镉达标期望概率为70%、80%、90%、100%时,土壤镉安全阈值分别为1.2 mg/kg、1.0 mg/kg、0.8 mg/kg及不能确定。采用吸收系数法计算的安全阈值为1.2 mg/kg,而直接采用监测数据的平均值代入回归方程得到的产地土壤安全阈值为1.5 mg/kg。不同安全需求下的土壤镉安全阈值有差异显著,运用回归方程法得出的结论高于令稻米镉含量达标率为70%的土壤镉安全阈值,吸收系数法得出的结论与令稻米镉含量达标率为70%的土壤镉安全阈值相一致。且结果均高于土壤环境质量标准二级镉阈值。     

鸟王茶产地土壤有机质含量特征及其影响因素

为了探索鸟王茶产地土壤有机质含量及其影响因素,促进贵州山区茶产业的优质高产发展,通过对不同生态环境下的鸟王茶产地土壤有机质含量进行研究。结果表明:鸟王茶产地土壤土壤有机质含量为10.08~107.09 g/kg,平均含量47.20 g/kg,变异系数为50.11%属中等程度的空间变异性,不同生态环境下鸟王茶产地土壤有机质含量大小为原生区域(59.32 g/kg)林地(57.28 g/kg)人工茶园(46.56 g/kg)耕地(34.8 g/kg)。鸟王茶产地土壤有机质含量分别为Ⅰ、Ⅱ,有机质含量丰富。表层土壤有机质含量与坡度呈极显著正相关关系,与海拔、石砾含量呈显著负相关关系。     

贵定鸟王茶产地土壤养分状况分析

通过对贵定县鸟王茶产地土壤进行检测,依照贵州省茶园(高产、中产、低产)土壤养分分级标准,对鸟王茶产地土壤养分状况进行分析。结果显示,贵定县鸟王茶产地土壤养分含量变化幅度较大,土壤有机质和碱解氮含量处于优良和尚可(Ⅰ级和Ⅱ级)的样品占总样品数的85%以上;有效磷和速效钾含量处于较差(Ⅲ级)的样品占总样品数90%。鸟王茶产地有机质和碱解氮含量较高;有效磷和速效钾含量处于较低水平。     

内蒙古不同产地甘草和土壤中重金属含量与评价

为研究内蒙古道地甘草产地土壤和甘草根重金属的含量特征和污染状况,选取鄂尔多斯杭锦旗、赤峰翁牛特旗和锡林郭勒盟正蓝旗三个产地,采集两个土层土壤(0—20cm,20—40cm),对重金属As、Hg、Cd、Pb和Cu的含量及相关性进行了分析.结果表明:三个产地土壤中As、Hg、Cd、Pb和Cu的含量均显著低于国家土壤环境质量一级标准;除鄂尔多斯土壤重金属As,赤峰土壤重金属As和Cu以及锡林郭勒盟土壤重金属Cd、Pb和Cu的含量高于内蒙古土壤背景值外,其他指标均显著低于内蒙古土壤背景值.用单项污染指数法、内梅罗综合污染指数法和潜在生态评价指数法评价产地土壤重金属的污染状况,结果表明三个产地土壤都是清洁的.土壤中As、Hg和Cu相互之间,均呈极显著负相关,可能这三种重金属之间存在着一种平衡和制约的关系;甘草根中As、Cd和Pb相互之间均呈极显著正相关;而土壤中重金属Pb与甘草根中重金属As、Cd和Pb呈极显著正相关,这也许能够为预防甘草重金属超标提供依据.另外,产地所采甘草根中五种重金属含量均显著低于药用植物及制剂外经贸绿色行业标准.     

贵州半夏产地土壤性状特征研究

为了研究半夏产地土壤性状,作者采集贵州半夏产地土壤进行理化分析,其结果表明:半夏产地土壤容重在0.76～1.37g/cm3之间,平均值为1.05g/cm3,土壤容重较小,土壤熟化程度较高;土壤含水量在21.56%～28.98%之间,平均25.58%,土壤pH值大部分适宜半夏生产。有机质含量地区差异较大,土壤营养元素中钾素充足,氮素和磷素含量低,应采用测土配方施肥技术,合理施肥。     

镇巴药用大黄规范化栽培规程

本规程按我国中药材GAP产品标准规定了秦巴山区药用大黄生产基地有关大黄规范化生产的综合技术要求。适用于秦巴山区大黄的生产区。本规程引用了大气、水质、土壤、农药质量标准,产品符合《中国药典》规定大黄质量标准。本规程规定了药用大黄的产地环境条件、栽培管理技术、采收与初加工及储藏技术等。     

漯河市郊土壤重金属污染调查与评价

通过对漯河市郊区土壤中Cu、Pb、Zn、Ni、Hg等物种重金属含量分析监测，分析统计漯河市郊区土壤中重金属含量，并对照先行国家土壤环境质量标准《土壤环境质量标准》（GB15618-1995），采用污染指数和超标率等指标说明土壤环境重金属污染现状。同时通过与土壤本底背景值对比，分析近30年漯河市郊区土壤重金属含量变化情况，为全国土壤环境污染防治提供基础资料。     

桃园土壤重金属污染评价及来源解析

以尉氏桃园为研究对象,对桃园土壤重金属来源进行污染评价及来源解析.通过对表层土壤中4种重金属(Cr、Pb、Zn、As)主成分分析,探讨桃园的土壤重金属形成原因,以无公害果园产地的土壤环境质量标准为依据,应用单因子污染指数法对土壤环境质量进行评价.分析结果表明,研究区重金属元素Cr的含量超出标准限值,且部分样点达到中度污染,此土壤环境质量不符合无公害水果生产的土壤环境质量标准,应给予严格的控制和治理.另外个别样点中类金属元素As的单项污染指数超出了0.7,达到了警戒限状态.主成分分析结果表明,土壤中4种重金属的富集原因存在差异,其中重金属As和Cr主要源于化肥、农药、有机肥的过量施用以及灌溉用水受污染;Zn和Pb主要源于粉尘及汽车轮胎磨损所产生有害气体中的重金属.     

甘肃主要当归产区土壤重金属含量比较分析

测定甘肃当归主产区土壤重金属含量并进行相关比较分析。采用ICP-MS法检测甘肃9个当归主产区共45批土壤中Pb、Cd、As、Hg、Cu 5种重金属元素含量,采用Excel软件包进行统计分析。结果 45批当归产地土壤符合GB 15618-1995一级标准相关规定的达91.11%,符合二级标准相关规定的达100.00%;漳县当归产地土壤中Pb、As元素含量最高,Cd、Cu元素含量较高;宕昌县As、Cu元素含量最高;临潭县Hg元素含量最高,Pb、As、Cu元素含量较高;和政县Pb、Cd元素含量较高;岷县、渭源县5种重金属元素含量均较低。9个主产地在当归GAP种植基地建设方面具有广阔的发展前景。     

鸟王茶产地土壤微量元素有效态特征及影响因素研究

本文研究了贵州省鸟王茶产地土壤微量元素有效态含量及其影响因素.结果表明:该地区野生茶园土壤有效态锌、铜、锰、铁含量显著或极显著高于人工茶园.表层(0～20cm)与其下层(20～40cm)土壤微量元素有效含量在0.01水平下差异性达到极显著.土壤pH与土壤有效态锌、铜、铁呈负相关性,表明土壤pH影响土壤微量元素有效含量;...     

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