Lead contamination in tea garden soils and factors affecting its bioavailability
Lead contamination in tea garden soils and factors affecting its bioavailability
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DOI：
10.1016/j.chemosphere.2004.11.058
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发表时间：
2005-05-01
期刊：
影响因子：
8.8
通讯作者：
Zhou, ZX
中科院分区：
文献类型：
--
作者：
Jin, CW;Zheng, SJ;Zhou, ZX
重金属的消费对人体健康有害，大多数国家限制食品和饮料中铅（Pb）等金属的浓度。最近的测试在某些商业品牌的茶叶中检测到高铅浓度，这一发现引起了生产者和消费者的担忧。为了探讨什么因素可能有助于增加茶叶中铅的积累，我们收集了茶叶和茶叶产地的土壤，并分析了它们的铅浓度，pH值和有机质含量。结果表明，47%的茶叶样品中铅含量超过2 mg·kg ~（-1），超过了国家规定的限量标准。表层和次表层土壤中的总铅含量平均值分别为36.4和32.2 mg kg（-1），低于中国有机茶园规定的60 mg kg（-1）限值。茶园土壤pH值为强酸性，最低pH值为3.37。老茶园下的土壤往往有一个较低的pH值和较高的铅的生物有效性，这是定义为提取量的铅比年轻的茶园。结果表明，土壤中生物有效态Pb浓度和生物有效态Pb占总Pb浓度的百分比与土壤H+活性和土壤有机质含量均呈正相关，其中有机质积累对Pb生物有效性的影响更大。因此，土壤酸化和有机质积累可提高土壤中Pb的生物有效性，从而促进茶叶对Pb的吸收和积累。(c)2004爱思唯尔有限公司保留所有权利。
The consumption of heavy metals is detrimental to human health and most countries restrict the concentration of metals such as lead (Pb) in food and beverages. Recent tests have detected high Pb concentrations in certain commercial brands of tea leaves and this finding has raised concerns for both producers and consumers. To investigate what factors may be contributing to the increase in Pb accumulation in the tea leaves we collected tea leaves and soils from tea producing areas and analyzed them for Pb concentration, pH and organic matter content. The result showed the Pb concentration of 47% investigated tea leaves samples was beyond 2 mg kg(-1), the permissible levels given by China. The total Pb concentration in the surface and subsurface soil layers averaged 36.4 and 32.2 mg kg(-1), respectively which fall below of the 60 mg kg(-1) limit provided for organic tea gardens in China. The pH of the tea garden soils was severely acidic with the lowest pH of 3.37. Soils under older tea gardens tended to have a lower pH and a higher Pb bioavailability which was defined as the amount of lead extracted by CaCl2 solution than those under younger tea gardens. We found that the concentration of bioavailable Pb and the percentage of bioavailable Pb (bioavailable Pb relative to total Pb concentration) were positively correlated with soil H+ activity and soil organic matter content, and the organic matter accumulation contribute more effects on Pb bioavailability in these two factors. We conclude that soil acidification and organic matter accumulation could contribute to increasing Pb bioavailability in soil and that these could increase Pb uptake and accumulation in the tea leaves. (c) 2004 Elsevier Ltd. All rights reserved.