基于同位素示踪技术分析小白菜中Pb的来源

为了探明乌鲁木齐市小白菜中Pb的污染来源,采用Pb同位素示踪法,结合盆栽试验种植小白菜,测定了成熟期小白菜不同部位Pb同位素单体计数值及其比值,分析了灌溉水、土壤、降尘对小白菜Pb的贡献率及小白菜Pb的可能来源.结果表明:大气降尘、灌溉水和土壤对小白菜地上部Pb的贡献率分别为51.50%、31.8%、16.7%,大气降尘对小白菜可食用部Pb含量的影响最大;对小白菜根系Pb累积的贡献率分别为2.20%、77.5%、20.30%,灌溉水对小白菜根系Pb含量累积的影响最大.尾气烟灰、燃煤、建筑降尘是导致乌鲁木齐市叶类蔬菜可食用部Pb含量超标的主要原因.

Analysis of Pb sources in chinese cabbage (Brassica campestris L.) based on isotope tracing technique

In order to find out the sources of Pb pollution in Chinese cabbage (Brassica campestris L.) in Urumqi, Pb isotope tracing technique was used in combination with potted Chinese cabbage. The Pb isotope monomers and their ratios in different parts of Chinese cabbage were determined during mature period, and the contribution rates of atmospheric dustfall, irrigation water and soil to Pb content in Chinese cabbage were analyzed, so did the possible sources of Pb in Chinese cabbage. The results showed that the contribution rates of atmospheric dustfall, irrigation water and soil to Pb in Chinese cabbage were 51.5%, 31.8% and 16.7%, respectively. The atmospheric dustfall exhibits the greatest impact on Pb content in edible parts of Chinese cabbage; concerning Pb accumulation in the root system of Chinese cabbage, those above three factors contribute respectively 2.2%, 77.5% and 20.3%, showing irrigation water has the greatest impact on Pb accumulation in Chinese cabbage roots. The main reasons explaining the excessive Pb content in edible parts of leaf vegetables in Urumqi are the exhaust, soot, coal burning and building dustfall.