茶叶的铅污染问题及铅污染的来源

介绍了我国茶叶中铅污染的大致情况,指出我国茶叶中的铅超标问题是一个不争的事实。土壤母质中铅含量较高本底值,土壤特有的理化性质,汽车运行的影响,有机肥料的影响,土壤微生物的影响,茶叶的加工过程,以及茶树本身的生理特征都可能是导致茶叶中铅含量超标的原因。当前,急需解决的问题是各个地区根据本地的实际情况,摸清茶叶铅污染的来源,并通过切实有效的途径来控制或缓解当地茶叶中铅污染问题。     

茶叶中的铅污染问题

介绍了研究茶叶中铅污染的意义以及污染现状,从地域上和时间上阐述了茶叶铅污染现象的一般规律,从土壤母质、环境空气、农药化肥三个方面介绍可能导致茶叶铅含量超标的原因。     

茶叶铅污染来源的研究进展

根据近年来国内外对茶叶铅污染研究的相关报道,综述了茶叶中铅污染的主要来源。这些来源主要包括:茶园土壤酸化和较高的有机质含量,大气沉降物中的铅和茶叶的加工过程。还根据各种茶叶铅污染来源的特征,有针对性地提出了一些防治措施。     

铅污染土壤的修复技术

综述了铅对土壤的污染及其修复技术。目前应用于污染土壤的修复技术可分为物理化学修复技术和生物修复技术。物理化学修复技术又可分为隔离包埋技术,固化稳定技术,Pyrometalluryical separation,化学稳定技术,电动修复技术等;生物修复技术可分为微生物修复技术和植物修复技术等。以期进一步推动铅污染土壤的治理和修复工作。     

成都市土壤-植物系统铅污染状况初步研究

为研究成都市土壤-植物系统铅污染状况，分析了成都市五种蔬菜及其根系土的铅含量。结果表明，土壤铅含量变化范围61．0～115．0mg/kg，均值为77．3mg/kg，所有样品含量均超过成都市土壤环境背景值，以城东和城南污染最为严重；蔬菜中铅含量以莴笋叶最高，萝卜最低，叶菜类高于瓜果类；蔬菜污染严重区与土壤污染区差别明显，说明土壤铅和植物铅污染源不同。     

中国铅污染的调查研究

阐述了中国铅污染的调查结果,包括:历史回顾、群体铅中毒事件、燃油铅污染、燃煤铅污染、铅中毒率统计和防治研究等6个部分。历史回顾从人类对铅污染危害认识的3次飞跃,反映了铅污染由公共卫生问题上升为人类社会问题;中毒事件调查,告诉人们企业的违规排铅,是铅中毒事件的罪魁祸首;燃油污染调查结果表明,汽油无铅化后,燃油大气铅年排放量比从前平均降低了98%左右;燃煤污染的调查结果表明,中国燃煤铅排放量年均增长9.55%,到2010年,中国燃煤铅排放量突破14 000 t,是汽车尾气铅排放量的35倍,且燃烧大气铅排放量与儿童铅中毒率之间存在显著的正相关关系;中毒率的调查结果表明,2003—2007年中国儿童铅中毒率平均为23.61%,比1994—2003年的35.27%有显著降低,但2007年为23.5%,比2006年的17.2%有所反弹;防治研究指出,中国对铅的研究主要是涉及铅毒理和铅污染防治等方面的研究,2006年发表铅文献量接近1 600篇。防治对策是污染源控制和人群监测,发铅与血铅监测同样可靠。     

古罗马食品和饮料的铅污染

罗马人用葡萄糖浆制备各种水果蜜饯和饮料,例如橄榄、李子、草莓、苹果、梨、桃子蜜饯等。制作这些食品也都在铅质容器中熬煮。饮料中有一种被称为adynamon的清淡饮料由葡萄糖浆和海水熬煮而成,它适合于久病体虚的患者,高等妓女也把它当作嗜好品。葡萄糖浆与没药可制成妇女适用的特殊饮料,与洋葱可制成流产药物,与茵陈制作的酒则适用于宿醉。生蜂蜜是一种良好的缓泻剂,但与葡萄糖浆烹调后则抗腹泻。此外,还有三种与蜂蜜有关的饮料。一种被称为蜜酒或蜜水,由蜂蜜与两倍体积的矿泉水混合而成;一种带酸味的蜂蜜制品被称为醋蜜,用蜂蜜与1 0倍海…     

沈阳市3～6岁儿童铅污染流行情况及对行为发育的影响

为了解沈阳市 3～ 6岁儿童血铅水平、铅污染流行情况及特征 ,采用石墨炉原子吸收方法对本市 1 0 84名 3～ 6岁儿童进行血铅含量测定 ,根据美国疾病控制中心 1 991年标准将血铅水平分为六级 ,观察了不同程度铅污染与儿童行为发育的关系。结果表明 ,血铅水平为 1 0 0 1 4± 39 83μg L ,铅污染流行率为 4 4 4 6 %。儿童铅污染程度与儿童行为发育异常呈正相关。揭示我市 3～ 6岁儿童血铅水平仍处于较高水平 ,铅污染以轻度为主 ,铅污染可影响儿童行为发育     

海产品铅污染状况以及铅的生物有效性研究进展

近海环境铅污染日益严重,就近期海产品铅污染状况及铅的生物有效性方面的研究进展做一综述。     

古罗马帝王生活的铅污染（三）

声名狼藉的科莫德斯·安托奈纳斯(公元1 77～1 92年在位)每天在皇宫、宴会厅和浴室中过着放荡不羁的生活,晚上穿梭于各酒店间直到黎明,大肆挥霍帝国财产。迪迪厄斯·朱利埃纳斯(公元1 93年在位)晚年成为老饕。佩斯森尼厄斯·尼日尔(公元1 93～1 94年在位)嗜酒如命,荒淫无度。克洛迪厄斯·阿尔宾努斯(公元1 96～1 97年在位)是著名大饕、醉汉。安托尼厄斯·卡勒卡勒斯(公元1 98～2 1 7年在位)和安托尼厄斯·吉特(公元2 0 9～2 1 1年在位)都是美食家和酒鬼,嗜血成性的暴君。埃勒加伯勒斯(公元2 1 8～2 2 2年在位)是安东尼王朝的末代皇帝,成天寻…     

Effect of Lead Contamination on Soil Microbial Activity Measured by Microcalorimetry

Microcalorimetry was used to investigate the microbial activity in three types of soil (orchard soil, crop soil, forest soil) in Wuhan, China, and to evaluate the influence of different concentrations of lead (Pb²⁺) on soil microbial activity. The experimental results revealed that due to different physical and chemical characteristics of the soils, soil microbial activity in three soil samples were in a descending sequence: orchards soil, crops soil, forest soil. Six levels of Pb viz. 0, 10, 20, 40, 80, 160 μg·g⁻¹ were applied in these soils, and the results showed that an increase of the amount of Pb²⁺ is associated with a decrease in microbial activity in the soils due to the toxic effect of Pb²⁺. In order to gain further insight of the sequential change of microorganisms, determination of colony forming units (CFU) was performed to provide a negative linear correlation between the heat effect and the respective number of microorganisms in the system.     

石墨炉原子吸收分光光度法测定茶叶中的铅

采用石墨炉原子吸收分光光度法测定了产自福建等地茶叶中的铅含量。方法的线性范围为0—80μg/L，回收率达91．7％-101．5％，相对标准偏差1．47％-3．88％。茶样检测结果表明，铅合格率为92．0％；不同茶类铅含量前3位由高到低依次为绿茶，乌龙茶，红茶；各类茶铅含量平均值为1．069mg／kg。     

石墨炉原子吸收法测茶叶中铅和镉

采用石墨炉原子吸收法测茶叶中铅、镉的含量,方法灵敏、准确,测定时无需富集、萃取,操作简便。铅、镉平均回收率分别为102.05%和94.98%,相对标准偏差不超过4.2%。     

气相色谱法测定参叶茶中农药残留量

利用气相色谱法同时测定了参叶茶中六六六和滴滴涕共 8种异构体的残留量 ,方法回收率为 78.0 %～ 1 0 0 .0 % ,最低检测浓度为 <1 .5ng/g,相对标准偏差 <1 0 .0 %。     

微波消解-ICP—MS法同时测定砖茶中的铅、铜、铬和16种稀土元素

采用微波消解处理样品,以电感耦合等离子质谱（ICP-MS）法同时测定砖茶中的铅、铜、铬和16种稀土元素。采用外标法绘制校准曲线,分析了茶叶国家标准物质GBW 10016,测定值与标准值吻合。检出限为0．055-0．765μg／蚝,样品测定结果的相对标准偏差为0．2％～4．7％（n=6）。用加标回收的方法评价了该方法的准确性,回收率为88．0％-102．7％。该方法测定结果与电热板湿法消解前处理测定结果相比差异不显著。     

Influencing Factors on the Physicochemical Characteristics of Tea Polysaccharides

Tea polysaccharides (TPSs) are one of the main bioactive constituents of tea with various biological activities such as hypoglycemic effect, antioxidant, antitumor, and immunomodulatory. The bioactivities of TPSs are directly associated with their structures such as chemical composition, molecular weight, glycosidic linkages, and conformation among others. To study the relationship between the structures of TPSs and their bioactivities, it is essential to elucidate the structure of TPSs, particularly the fine structures. Due to the vast variation nature of monosaccharide units and their connections, the structure of TPSs is extremely complex, which is also affected by several major factors including tea species, processing technologies of tea and isolation methods of TPSs. As a result of the complexity, there are few studies on their fine structures and chain conformation. In the present review, we aim to provide a detailed summary of the multiple factors influencing the characteristics of TPS chemical structures such as variations of tea species, degree of fermentation, and preparation methods among others as well as their applications. The main aspects of understanding the structural difference of TPSs and influencing factors are to assist the study of the structure and bioactivity relationship and ultimately, to control the production of the targeted TPSs with the most desired biological activity.     

Preparation and Properties of Biodegradable Spent Tea Leaf Powder/Poly(Propylene Carbonate) Composite Films

The aim of the present work is to develop novel bio-based lightweight material with improved tensile and thermal properties. Spent tea leaf powder (STLP) was used as a filler to improve the tensile and thermal properties of polypropylene carbonate (PPC). Tea is an important material used in hotels and households, and spent tea leaf is a resulting solid waste. Composite films with STLP were obtained by the solution casting method. These films were characterized by optical and scanning electron microscopy, Fourier transform-infrared spectroscopy, thermogravimetric analysis, and tensile testing to examine the effect of filler content on the properties of the composites. The results showed that composite films have increased tensile strength due to enhanced interfacial adhesion between the filler and the matrix. In addition, the composite films also exhibited higher thermal degradation temperatures than pure polypropylene carbonate. The morphology results indicate that there is a good interface interaction between STLP and PPC. Results of the study reveal STLP to be a promising green filler for polymer plastics.