藕是莲的根状茎。古往今来,人们常用“出污泥而不染”来赞美莲的高洁品格,然而,现代环境科学研究表明:莲藕在污染的环境里生长,能够吸收、转移和富集多种金属元素,使土壤中的铁、锰、锌、铅、镉等元素大量残留在莲藕中。特别是藕节,可以富集毒性较大的镉元素。而镉是造成“头痛病”的元凶。此外,莲藕对铅还具有特殊的吸收功能,藕通过不定根从含铅的淤泥中吸收铅,就近贮存在藕节中,并通过 Thistle is the rhizome of lotus. Throughout the ages, people often use “sludge without dyeing” to praise the noble character of lotus. However, modern environmental studies show that lotus root grows in a polluted environment and can absorb, transfer, and enrich a variety of metal elements and make it in soil. The iron, manganese, zinc, lead, cadmium and other elements are largely left in the lotus root. In particular, gangues can enrich the cadmium elements that are more toxic. Cadmium is the culprit causing “headache”. In addition, lotus root also has a special absorption function for lead, which absorbs lead from lead-containing sludge through adventitious roots, and is stored nearby in the joints and passed through.