The newly introduced Cd (Cd_N) has different environmental fates than legacy Cd (Cd_L) and how to distinguish them in soil under different amendments is crucial for understanding natural aging and engineered remediation of Cd pollution in soil. In this study, enriched stable isotope tracer (¹¹²Cd) was introduced to distinguish the fate of Cd_N and Cd_L in paddy soil under pH adjustment and quicklime, slaked lime, and biochar amendments. The behaviors of Cd_N and Cd_L were studied during 56 days of flooding incubation through overlying water analysis, sequential extraction fractionation and lability (exchangeable pool probed by ¹¹⁰Cd isotopic spike) assessment. The results showed that soil pH is the main driving factor controlling the partition of both Cd_N and Cd_L in overlying water. During the incubation, Cd_N transformed quickly from soluble fraction to residual fraction under all treatments. In addition, at the end of the incubation, Cd_N concentrations in residual fraction were much higher than that of Cd_L, suggesting a more thorough aging of Cd_N than Cd_L. The labile Cd_N (ECd_N) under pH adjustment and biochar amendment decreased during incubation and ECd_N% was essentially the same with that of ECd_L% after 28 days, indicating the aging equilibrium of exchangeable pool of Cd_N.

新引入的Cd（Cd _N）与传统Cd（Cd _L）具有不同的环境命运，如何在不同的修正条件下区分土壤中的镉对于理解自然老化和土壤中Cd污染的工程修复至关重要。在这项研究中，引入了富集的稳定同位素示踪剂（¹¹² Cd）来区分在pH调节和生石灰，熟石灰和生物炭改良剂作用下水稻土中Cd _N和Cd _L的命运。通过上覆水分析，依序萃取分级分离和不稳定性（由¹¹⁰探测的可交换池）研究了水淹孵育56天中Cd _N和Cd _L的行为。镉同位素加标）评估。结果表明，土壤pH是控制上覆水中Cd _N和Cd _L分配的主要驱动因素。在温育期间，镉_Ñ迅速转化从可溶级分以下所有的处理残余馏分。另外，在孵育结束时，残留部分中的Cd _N浓度要比Cd _L高得多，这表明Cd _N的老化要比Cd _L更彻底。在培养过程中，pH调节和生物炭修正下的不稳定Cd _N（ECd _N）降低，ECd _N％与ECd基本相同28天后的_L％，表明Cd _N交换池的老化平衡。