Temporal and Tissue-specific Accumulation and Chemical Fractionation of Heavy Metal(loid)s in Angelica dahurica...

Accurate safety evaluation of medicinal and edible plants requires a deep understanding of heavy metal(loid) behavior during growth. To address this, we characterized the accumulation dynamics, chemical fractionation, and health risks of Pb, Cd, As, Hg, and Cu in Angelica dahurica across a complete growth cycle. Samples of roots, stems, and leaves were collected monthly from April to August and analyzed using Tessier sequential extraction. The results revealed distinct temporal and tissue-specific accumulation patterns; specifically, Pb, Cd, As, and Cu generally exhibited a decreasing trend during plant growth, with the highest concentrations predominantly found in the leaves. Pb, Hg, and Cu existed primarily in the exchangeable (F1) and carbonate-bound (F2) fractions, which were considered the absorbable fraction and represented the most bioavailable chemical forms. Health risk assessments indicated that consuming Angelica dahurica roots poses non-carcinogenic risks to children and adults in April (with children exhibiting nearly four-fold greater susceptibility), while Cd-dominated carcinogenic risks also exceed the safety thresholds. Furthermore, both non-carcinogenic and carcinogenic risks exhibit a declining trend over the growth period, with risk values based on the absorbable fraction consistently being approximately half of those based on the total content. Incorporating chemical fractionation offers a more realistic safety evaluation than traditional total concentration methods. These findings provide a scientific basis for agricultural management and the establishment of precise safety standards, thereby supporting the sustainable utilization of Angelica dahurica.