福建安溪茶园土壤铅粒级分布及有效性特征

发布时间：2018-05-29 01:10

本文选题：土壤粒级 + 土壤铅含量　；参考：《中国地质大学(北京)》2015年硕士论文

【摘要】：茶叶是我国和全球范围内的重要饮料,茶叶铅超标曾经是社会关注的热点问题。大量研究表明,茶叶中铅的主要来源是土壤,土壤铅含量是决定茶叶铅含量的主导因素;土壤中重金属元素存在形态是决定其生物有效性和生态效应的关键,土壤铅存在形态及其有效量与茶叶铅含量关系是近年来的研究热点。本文以福建安溪铁观音茶叶主产区为研究区,采样测定了56个茶园表土、亚表土、茶叶中铅等元素含量,选取典型表土、亚表土样品各27件,超声振动筛分成5个粒级,进一步研究了土壤铅粒级分配规律及4种提取态含量。研究表明,福建安溪地区土壤铅平均含量约为我国土壤铅背景值的二倍,表层和亚表层中土壤铅含量变化不大。土壤铅的粒级分布不均匀,具有在土壤细粒级中富集的特征。4种方法提取结果表明,表层土壤铅提取量大小顺序为:络合剂提取酸提取盐提取水提取,亚表层土壤铅提取量大小顺序为:酸提取络合剂提取盐提取水提取,络合剂提取和酸提取的有效态铅含量相近并远大于盐提取和水提取的有效态铅含量。除了水提取态铅外,盐提取、酸提取、络合剂铅提取量均随土壤粒级的减小而增加。土壤全量铅与茶叶铅含量呈正相关关系,据此可建立茶叶—土壤铅含量关系模型。茶叶铅含量与土壤有效态铅含量的相关性明显高于与土壤全量铅的相关性,因此土壤有效态铅含量更能反映土壤铅的生态风险,对比表明0.1mol/L稀盐酸和混合络合物溶液(0.02mol/L EDTA+0.5mol/L HOAc+0.5mol/L NH4OAc)提取效果最好。建立了茶叶铅含量与土壤理化指标的多元线性回归方程,结果表明p H值、粘粒组分、Corg、CEC等土壤理化对于茶叶铅含量有一定的影响,但是影响程度较低,土壤铅含量是茶叶铅含量的主导和决定因素。本项研究成果为安溪茶园土壤铅生物有效性评价方法的建立、土壤铅污染对茶叶安全质量的评价预测提供了重要依据。
[Abstract]:Tea is an important beverage in our country and the whole world. A large number of studies have shown that the main source of lead in tea is soil, and the lead content in soil is the leading factor to determine the content of lead in tea, and the form of heavy metal elements in soil is the key to determine its biological availability and ecological effect. The relationship between the forms of lead in soil and the content of lead in tea has been a hot research topic in recent years. In this paper, the contents of lead in 56 tea garden topsoil, subsurface soil and tea were determined in the main tea production area of Anxi Tieguanyin Tea, Fujian Province. The typical topsoil, 27 subsurface soil samples were selected, and the ultrasonic vibrating screen was divided into 5 grain levels. The distribution law of lead particles and the contents of four kinds of extractable species in soil were further studied. The results show that the average content of soil lead in Anxi area of Fujian Province is about twice as high as the background value of soil lead in China. The content of lead in topsoil and subsurface layer does not change much. The grain-size distribution of lead in soil was uneven, and the extraction results showed that the extraction amount of lead in surface soil was in the order of complexing agent extraction, acid salt extraction and water extraction. The order of the amount of lead extraction in subsurface soil was as follows: acid extraction complex agent extraction salt extraction water extraction, the effective lead content of complex agent extraction and acid extraction were similar and much larger than the available lead content of salt extraction and water extraction. Except water extraction, salt extraction, acid extraction and complexing agent lead extraction increased with the decrease of soil particle size. There was a positive correlation between total lead content in soil and lead content in tea, based on which a model of tea-soil lead content relationship could be established. The correlation between tea lead content and soil available lead content was significantly higher than that with total soil lead content, so the soil available lead content could reflect the ecological risk of soil lead. The comparison shows that the extraction efficiency of 0.1mol/L dilute hydrochloric acid and mixed complex solution is 0.02mol / L EDTA 0.5mol/L HOAc 0.5mol/L NH4OAc. The multivariate linear regression equation between tea lead content and soil physical and chemical index was established. The results showed that soil physicochemical properties such as pH value, clay component Corgfen CEC had some influence on tea lead content, but the influence degree was low. Lead content in soil is the leading and decisive factor of lead content in tea. The results of this study provide an important basis for the establishment of biological evaluation method of soil lead in Anxi tea garden and the evaluation and prediction of tea safety quality by soil lead pollution.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53

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