A semi-mechanistic aging model of Pb added to soil by a modified stable isotope dilution technique

• Published in: Scientific reports Vol. 14; no. 1; pp. 18662 - 13
• Main Authors: Ji, Xuezhi, Li, Jumei, Sun, Shuo, Zhong, Ying, Ma, Yibing
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 12.08.2024; Nature Publishing Group; Nature Portfolio
• Subjects: 631/158/2456; 704/158/2466; 704/172/169/896; Acetic acid; Acidic soils; Aging; Aging model; Agricultural land; E-value; Edetic acid; Humanities and Social Sciences; Lead; multidisciplinary; Organic matter; Organic soils; Science; Science (multidisciplinary); Soil; Soil pH; Soils; Stable isotope dilution; Stable isotopes; Stable isotope dilution; Lead; Soil; Aging model; E-value
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-024-69375-7

The aging of Pb added to soils has not been studied by the isotopic technology because of difficulties in determination of isotopically exchangeable Pb in soil, so that a set of 10 typical agricultural soils in China and a one-year aging experiment with the addition of water-soluble Pb to the soils were carried out. A modified stable isotope dilution technique to determine isotopically exchangeable Pb in soil was developed where 0.2 mM EDTA (ethylenediaminetetraacetic acid) as the extractant. When water-soluble Pb was added to soil, the isotopically exchangeable Pb (E add %, the percentage of isotopically exchangeable Pb to total Pb added to soil) initially decreased rapidly and gradually slowly. A semi-mechanistic aging model of Pb added to soils, including precipitation/nucleation (Y 1 ), micropore diffusion (Y 2 ), and organic matter encapsulation processes (Y 3 ) was developed with the root mean square error 8.3% where Y 1 , Y 2 , and Y 3 accounted for 0.02~26.9%, 1.4~21.8% and 3.8~11.3%, respectively, when the pH 4.0~8.0 and organic matter 2.0~6.0%. Soil pH was a vital factor affecting the aging rate. When the pH increased by 1 unit, the E add value decreased by approximately 9%. The model could be used to scale ecotoxicological data of Pb in soil generated in different aging times.