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。     

非土壤因素对茶叶铅污染的影响

通过对18个茶叶生产厂家的分析调查发现,精制茶的生产工艺对茶叶的铅含量在总体上有降低作用,而粗制茶的加工工艺却有增加的趋势,因此茶叶生产工艺对茶叶的铅含量影响很大。通过用水清洗鲜叶发现,茶叶表面有相当一部分的铅可以洗脱下来,这说明在茶叶的种植过程中,大气中粉尘沉降对茶叶也有铅污染的作用。据此提出了一些建议和改进措施。     

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。     

环境铅污染与人体健康

铅污染已成为现实环境的主要污染物，对人体尤其是儿童的健康存在严重的危害，如何减少直至清除环境铅污染是当前全社会的一个重要问题。     

综合防治铅污染问题

讨论了人发中铅，锌含量与年龄变化的关系，提出了综合防治的建议。     

铅污染与儿童健康

综述了环境铅污染与儿童健康的关系,包括：儿童铅中毒的原因,铅对儿童健康的危害和儿童铅污染的防治等,主要参考文献７篇。     

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。     

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。     

城市环境铅污染状况研究

介绍了邢台近１０年来环境灰尘，土壤，地面水，地下水，大气及部分作物的铅污染和累积状况，并分析了产生原因及影响。     

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%。     

Speciation of Manganese in Tea Leaves and Tea Infusions

Abstract

A speciation scheme was developed for identification of the chemical forms of manganese in tea leaves and tea infusions. The range of manganese in five different groups of tea leaves was found to be 1107 – 2205 μg/g on a dry basis. It was noted that 30.0% of Mn was passed into the water that was present in the form of Mn(II), and also 2.5% of Mn was found as the total organic bound fraction and passed into the various solvents.     

铅毒性的研究进展

对铅的毒性,包括对骨髓造血系统、免疫系统、神经系统以及其他毒害作用进行了综述。大量研究表明,铅对机体损伤呈多系统性、多器官性。铅作为中枢神经毒物,对儿童的健康和智能的危害更严重。必须采取积极措施防治铅污染。     

Research Progress on Fumonisin B1 Contamination and Toxicity: A Review

Fumonisin B1 (FB1), belonging to the member of fumonisins, is one of the most toxic mycotoxins produced mainly by Fusarium proliferatum and Fusarium verticillioide. FB1 has caused extensive contamination worldwide, mainly in corn, rice, wheat, and their products, while it also poses a health risk and is toxic to animals and human. It has been shown to cause oxidative stress, endoplasmic reticulum stress, cellular autophagy, and apoptosis. This review focuses on the current stage of FB1 contamination, its toxic effects of acute toxicity, immunotoxicity, organ toxicity, and reproductive toxicity on animals and humans. The potential toxic mechanisms of FB1 are discussed. One of the main aims of the work is to provide a reliable reference strategy for understanding the occurrence and toxicity of FB1.     

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.